JP2005188339A - Displacement-on-demand internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibration and noise at the time of resuming fuel supply in a displacement-on-demand internal combustion engine. <P>SOLUTION: The displacement-on-demand internal combustion engine comprises a displacement-on-demand region setting means for setting a displacement-on-demand region in which partial cylinder operation is performed, and a fuel controlling means for performing fuel supply resumption after a fuel cut. Lower limit rotation speeds Na, Nb in the displacement-on-demand region are set larger by predetermined values ΔNa, ΔNb than resumption rotation speeds Nra, Nrb which are engine rotation speeds at the time of resuming the fuel supply and the fuel supply resumption is carried out in condition of the all cylinder operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cylinder that switches the operation mode of an internal combustion engine in which fuel cut is performed between an all-cylinder operation in which all cylinders are operated and a partial cylinder operation in which some cylinders are deactivated in accordance with a vehicle operation state including the engine speed. The present invention relates to a variable cylinder internal combustion engine having number control means.

In the variable cylinder internal combustion engine, the fuel efficiency is improved by reducing the pumping loss in the partial cylinder operation, but the engine torque generated in the operating cylinder is larger than in the case of the full cylinder operation. The engine torque generation interval (crank angle) increases, and the vibration of the internal combustion engine increases. Therefore, for example, there is an automobile engine disclosed in Patent Document 1 as a technique for improving fuel efficiency while suppressing this vibration. In order to suppress vibration and noise during low-speed rotation of the engine, this engine is provided with a map in which the setting condition of the cylinder rest state is changed according to ON / OFF of the idle switch, and the engine speed is set to ON of the idle switch. / When the rotation speed is equal to or higher than a predetermined rotational speed set according to OFF, the cylinder resting state is set. The predetermined rotational speed when the idle switch is on is set lower than the predetermined rotational speed when the idle switch is off.
JP-A-5-180016

  In an internal combustion engine in which fuel cut is performed at the time of deceleration in order to improve fuel consumption performance, fuel return is performed after the fuel cut ends, and fuel supply is resumed, thereby generating vibration and noise of the internal combustion engine. The vibration and noise at the time of fuel return are larger when the fuel is returned in the partial cylinder operation than the case of the fuel return in the all cylinder operation due to the above-described reason.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce vibration and noise when returning fuel in a variable cylinder internal combustion engine. Furthermore, the present invention has the object of enlarging the cylinder resting region.

  According to the first aspect of the present invention, a throttle valve that measures intake air, a rotation speed sensor that detects engine rotation speed, and a cylinder recovery region that sets a cylinder recovery region in which partial cylinder operation in which some cylinders are stopped is performed. A setting unit; a determination unit that determines whether or not the engine rotational speed is in the cylinder deactivation region based on a detection result of the rotation speed sensor; and a cylinder that sets the number of operating cylinders based on the determination result of the determination unit A number control unit, a cylinder deactivation mechanism provided in some of the cylinders, and a fuel control unit that executes fuel return after a fuel cut, and the cylinder number control unit controls the cylinder deactivation mechanism, thereby In a variable cylinder internal combustion engine in which the operation mode is switched between full-cylinder operation in which all cylinders operate in a region other than the idle cylinder region and partial cylinder operation in the idle cylinder region, the lower limit rotational speed of the idle cylinder region A engine speed when returning than the return rotation speed is larger variable cylinder internal combustion engine by a predetermined value.

  According to this, since the lower limit rotational speed of the non-cylinder region where the partial cylinder operation is performed is larger than the return rotational speed at which the fuel return is performed after the fuel cut, the engine return speed is lower than the lower limit rotational speed. Since the operation is performed in an all-cylinder operation state in a region other than the cylinder deactivation region, which is the region, the generation of vibration and noise at the time of fuel return is suppressed compared to the case where fuel return is performed in the state of partial cylinder operation.

  According to a second aspect of the present invention, in the variable cylinder internal combustion engine according to the first aspect, the cylinder deactivation mechanism is a hydraulic mechanism driven by hydraulic oil, and the predetermined value depends on a temperature or pressure of the hydraulic oil. It is set to a different value.

  According to this, when the fuel is restored, the cylinder deactivation stop mechanism is in a state in which all cylinders can be operated reliably, and the predetermined value can be set as small as possible according to the temperature or pressure of the hydraulic oil. The cylinder area is enlarged.

  According to a third aspect of the present invention, in the variable cylinder internal combustion engine according to the first or second aspect, the cylinder deactivation mechanism is provided in each of the plurality of the partial cylinders, and is disposed at a rotational position of the crankshaft. Accordingly, switching between the non-operating state and the operating state is sequentially performed, and the predetermined value is set to a different value according to the return rotational speed.

  According to this, at the time of fuel return, the cylinder deactivation stop mechanism is in a state in which all cylinders can be operated reliably, and the predetermined value can be set to a value as small as possible according to the return rotation speed.

  According to invention of Claim 1, the following effect is show | played. That is, since fuel return is performed in the state of all cylinder operation, generation of vibration and noise at the time of fuel return is suppressed, and vibration and noise of the internal combustion engine are reduced.

  According to invention of Claim 2, in addition to the effect of the invention of the cited claim, there exists the following effect. That is, all cylinder operation at the time of fuel return is ensured, and the cylinder deactivation region in the variable cylinder internal combustion engine having a cylinder deactivation mechanism comprising a hydraulic mechanism is expanded, so that the operation region of partial cylinder operation is expanded and fuel consumption is increased. The performance is further improved.

  According to invention of Claim 3, in addition to the effect of the invention of the cited claim, there exist the following effects. That is, all cylinder operation at the time of fuel return is ensured, and the cylinder deactivation region in the variable cylinder internal combustion engine having a cylinder deactivation mechanism that is sequentially switched according to the rotational position of the crankshaft is expanded, so that operation of partial cylinder operation is performed. The range will be expanded and fuel efficiency will be further improved.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIG. 1, a variable cylinder internal combustion engine E to which the present invention is applied is a V-type 6-cylinder 4-stroke internal combustion engine, and is installed in a horizontal arrangement in which the rotation center line of a crankshaft D is directed in the vehicle width direction. Mounted on.

  The internal combustion engine E includes a first bank Ba having three front cylinders C1 to C3 constituting the first cylinder group, and a second bank Bb having three rear cylinders C4 to C6 constituting the second cylinder group. Is provided. A plurality of cylinders C4 to C6, which are some cylinders of the internal combustion engine E and are cylinders that can be deactivated, are each provided with a valve deactivation mechanism 1 as cylinder deactivation means for switching operation and deactivation of the cylinders C4 to C6. The operation of the valve deactivation mechanism 1 is controlled by cylinder number control means 23 (see FIG. 2).

  The valve operating device of the internal combustion engine E includes a valve operating cam provided on a cam shaft that is rotationally driven by the power of the crankshaft D, and the cylinder head of each bank Ba, Bb is provided for each of the cylinders C1 to C6 by the valve operating cam. Opens and closes the intake and exhaust valves located in The well-known valve pause mechanism 1 is constituted by a hydraulic mechanism that is switched between a non-actuated state and an actuated state by hydraulic oil, and is provided in the valve operating device disposed in the second bank Bb. The valve suspension mechanism 1 is connected to an oil passage 3 provided with a hydraulic control valve 2 that is controlled by an electronic control unit (hereinafter referred to as “ECU”) 20 according to the vehicle operating state described later. The oil passage 3 is connected to an oil pump P as a hydraulic source driven by the internal combustion engine E, and the hydraulic control valve 2 controls the supply and discharge of the hydraulic oil to and from the valve pause mechanism 1, whereby the valve pause mechanism 1 Corresponding to the rotational position of the shaft D, the cylinders C4 to C6 are sequentially switched to the non-operating state or the operating state.

  When the valve deactivation mechanism 1 is in the non-operating state, the intake valves and exhaust valves of the respective cylinders C4 to C6 of the second bank Bb are opened and closed at a predetermined opening and closing timing by the valve cams, and the cylinders C4 to C6 are opened and closed. When the valve is deactivated and the valve deactivation mechanism 1 is in the activated state, the intake valves and exhaust valves of the cylinders C4 to C6 are deactivated and kept closed, and the cylinders C4 to C6 are deactivated.

  Therefore, the operation mode of the internal combustion engine E is such that the valve deactivation mechanism 1 is deactivated by the cylinder number control means 23 (see FIG. 2) for controlling the number of operating cylinders, and the three cylinders C4 to C6 in the second bank Bb. Is activated, all cylinders C1 to C6 are operated together with the three cylinders C1 to C3 of the first bank Ba, and the valve deactivation mechanism 1 is activated, and the three cylinders C4 to C6 of the second bank Bb are activated. The operation is stopped and the operation is switched to the partial cylinder operation in which the three cylinders C1 to C3 of the first bank Ba are operated.

  The internal combustion engine E includes an intake device 4 having a throttle valve 6 that measures air taken into the cylinders C1 to C6 through the air cleaner 5, and an intake manifold 7 that distributes intake air to the cylinders C1 to C6. The fuel mixture is ignited by the spark plug 9 (see FIG. 2) in the combustion chambers belonging to the cylinders C1 to C6 and the fuel injection valve 8 as fuel supply means for supplying fuel to the air to form the mixture. And an exhaust device 10 having an exhaust manifold 11 for discharging the generated combustion gas to the outside as exhaust gas. The throttle valve 6 is driven by an electric motor 12, which is an actuator controlled by the ECU 20, and the opening degree is controlled according to the accelerator operation amount and the vehicle driving state described later.

  Referring also to FIG. 2, the valve pause mechanism 1, the fuel injection valve 8, the spark plug 9 and the electric motor 12 are controlled by the ECU 20. The ECU 20 is composed of a microcomputer including a storage device such as an input / output interface, a central processing unit (CPU), a ROM storing various control programs and various maps, and a RAM storing various data temporarily. Is done.

The driving state detection means 30 for detecting the vehicle driving state consisting of the engine operating state of the internal combustion engine E such as the engine speed and the state other than the engine operating state such as the vehicle speed is connected to the ECU 20 or by the ECU 20. Composed.
Therefore, the control device for switching the operation mode of the internal combustion engine E includes the operation state detection means 30 and the ECU 20.

  The driving state detection means 30 comprises a vehicle speed sensor 31 for detecting the vehicle speed, an accelerator operation amount detection means for detecting the depression amount of the accelerator pedal as an accelerator operation amount, and an accelerator sensor 32 that is also an engine load detection means, a throttle valve A throttle opening sensor 33 for detecting the opening degree of the engine 6, a rotation speed sensor 34 for detecting the engine rotation speed of the internal combustion engine E, and the deceleration of the internal combustion engine E based on the reduction rate of the engine rotation speed and the reduction rate of the vehicle speed. Deceleration detecting means 35 for detecting, a fully closed sensor 36 for detecting the fully closed state of the throttle valve 6 based on the detection result of the accelerator sensor 32, and a temperature sensor 37 for detecting the temperature and pressure of the hydraulic oil of the valve deactivation mechanism 1 respectively. And a pressure sensor 38.

  The ECU 20 is based on the detection result of the idle state setting means 21 for setting the idle cylinder region F (see FIG. 3), which is the operation region in which the partial cylinder operation is performed, and the detection result of the operating state detection unit 30. The determination means 22 for determining whether or not the cylinder region F is present, the cylinder number control means 23 for setting the number of operating cylinders based on the determination result of the determination means 22, and the detection results of the operating state detection means 30 Fuel control means 24 for controlling the amount and timing of fuel supplied from the fuel injection valve 8 and spark plug control means 25 for controlling the ignition timing and operation of each spark plug 9 based on the detection result of the operating state detection means 30. With.

  Referring also to FIG. 3, the idle cylinder region setting means 21 sets the idle cylinder region F based on the idle cylinder region map stored in the storage device of the ECU 20. The basic idle cylinder area Fo set by the idle cylinder area map is, for example, the internal combustion engine E over a predetermined range of the engine load area and the engine rotation speed area with the engine load and the engine rotation speed of the internal combustion engine E as parameters. Is set as an operation region in a low load region and in a predetermined low speed rotation region or medium speed rotation region.

  The lower limit rotational speed No, which is a boundary value on the low rotational speed side of the engine rotational speed region in the basic cylinder region Fo, is a return rotational speed Nra, Nrb (see FIG. 4) set from the viewpoint of preventing engine stall. In view of improving quietness in the passenger compartment and passenger comfort, vibration and noise generated when the internal combustion engine E is operated in partial cylinder operation may cause the passengers to be extremely uncomfortable. It is set as the engine speed that does not exceed the vibration / noise level that is not a guideline.

  The cylinder number control means 23 controls the valve deactivation mechanism 1 so that the partial cylinder operation is performed when the determination means 22 determines that the vehicle operating state including the engine rotation speed is in the idle cylinder region F. When the number of operating cylinders is set to be less than the total number of cylinders, in this case, three cylinders, which is half of the total number of cylinders, and it is determined that the vehicle operating state is an operating region other than the idle cylinder region F, The valve deactivation mechanism 1 is controlled so that the number of operating cylinders is set to the total number of cylinders.

  The fuel control means 24 stops the supply of fuel from the fuel injection valves 8 belonging to the cylinders C4 to C6 during the partial cylinder operation according to the output signal from the cylinder number control means 23. Further, when the fuel control means 24 detects a sudden deceleration in which at least one of the engine speed reduction rate and the vehicle speed reduction rate is greater than or equal to a predetermined value by the deceleration detection means 35, the fuel injection valves 8 of the cylinders C1 to C6. A fuel cut to stop the fuel supply from is executed. In this embodiment, since the fuel cut is performed during the partial cylinder operation, the fuel cut is substantially performed on the fuel injection valves 8 belonging to the cylinders C4 to C6. After the fuel cut, when the engine rotational speed detected by the rotational speed sensor 34 decreases to the return rotational speeds Nra and Nrb (see FIG. 4) for executing the fuel return, as described later, the cylinders C1 to C6 The fuel supply from the fuel injection valve 8 is resumed. Further, the ignition plug control means 25 stops the operation of the ignition plugs 9 belonging to the cylinders C4 to C6 during the partial cylinder operation in accordance with the output signal from the cylinder number control means 23.

  3 and 4, the return rotational speed Nra is the return rotational speed when the throttle valve 6 is fully closed (when fully closed), and the return rotational speed Nrb is when the throttle valve 6 is not fully closed. This is the return rotation speed (when not fully closed). Both return rotational speeds Nra and Nrb are set based on the vehicle operating state such as the shift position of the transmission when the internal combustion engine E returns to fuel. Specifically, the return rotation speed Nra is set by performing correction by subtracting a predetermined correction value from the return rotation speed Nrb set by a map using the shift position as a parameter.

  The idle cylinder region setting means 21 fully throttles and non-fully closes the throttle valve 6 detected by the fully-closed sensor 36, and corrects the lower limit rotational speed No according to both return rotational speeds Nra and Nrb. The lower limit rotational speed Na when the throttle valve 6 is fully closed, and the lower limit rotational speed Nb when the throttle valve 6 is not fully closed are set, and the fully closed cylinder region Fa and the throttle when the throttle valve 6 is fully closed are set. The non-fully closed cylinder region Fb when the valve 6 is not fully closed.

  Specifically, as the engine torque determined based on the opening degree of the throttle valve 6 increases, the vibration and noise during partial cylinder operation also increase. Therefore, the engine torque is lower than when the throttle valve 6 is not fully closed. The lower limit rotational speed Na when the throttle valve 6 in the small operating state is fully closed is set smaller than the lower limit rotational speed Nb when the throttle valve 6 is not fully closed. Therefore, the fully closed closed cylinder region Fa defined by the lower limit rotational speed Na includes a lower engine rotational speed region than the non-fully closed closed cylinder region Fb defined by the lower limit rotational speed Nb. Region F is entered.

  Therefore, the lower limit rotational speed Na is set to a value that is larger by a predetermined value ΔNa than the return rotational speed Nra with reference to the return rotational speed Nra, and the lower limit rotational speed Nb is returned based on the return rotational speed Nrb. The rotation speed Nrb is set to a value that is larger by a predetermined value ΔNb.

  The predetermined values ΔNa and ΔNb indicate that the valve deactivation mechanism 1 is activated in all the cylinders C4 to C6 that are deactivated until the engine rotation speed reaches the return rotation speeds Nra and Nrb from the lower limit rotation speeds Na and Nb, respectively. Is set by the cylinder deactivation region setting means 21 so as to complete the switching from the non-operating state to the non-operating state. Therefore, in the valve deactivation mechanism 1 in which the switching time is affected by the temperature and pressure of the hydraulic oil, the predetermined values ΔNa and ΔNb are based on the maps with the hydraulic oil temperature or pressure shown in FIGS. 5 and 6 as parameters. It is set to a different value depending on the temperature or pressure of the hydraulic oil. Specifically, as shown in FIG. 5, based on the detection result of the temperature sensor 37 (see FIG. 2) or the pressure sensor 38 (see FIG. 2) provided in the oil passage 3 for the hydraulic oil, the temperature of the hydraulic oil The lower the pressure is and the higher the viscosity is, the greater the force that the hydraulic oil pushes on the switching member. Therefore, the higher the hydraulic oil temperature, the higher the pressure, and the higher the pressure, as shown in FIG. It is set to a smaller value.

  Further, the valve deactivation mechanism 1 is provided in a plurality of cylinders C4 to C6, and switching between the operation state and the non-operation state of the valve deactivation mechanism 1 is sequentially performed in those cylinders corresponding to the rotational position of the crankshaft D. The predetermined values ΔNa and ΔNb are set to different values according to the return rotational speeds Nra and Nrb based on the map with the engine rotational speed shown in FIG. 7 as a parameter. Specifically, based on the detection result of the rotational speed sensor 34 (see FIG. 2), as the return rotational speeds Nra and Nrb are lower, the larger the value is set, as shown in FIG.

  When the predetermined values ΔNa and ΔNb are set according to the temperature or pressure of the hydraulic oil and the return rotational speeds Nra and Nrb, the maximum predetermined values ΔNa and ΔNb set by these parameters are adopted. Further, the lower limit rotational speeds Na and Nb and the return rotational speeds Nra and Nrb are respectively hysteresis characteristics having a predetermined width in order to stabilize the switching of the valve deactivation mechanism 1 and stabilize the operation of the internal combustion engine E at the time of fuel return. have.

Next, operations and effects of the embodiment configured as described above will be described.
The determining means 22 determines whether or not the vehicle operating state including the engine rotational speed is in the cylinder deactivation region F based on the detection result of the operating state detecting means 30 including the rotational speed sensor 34, and the cylinder number control means 23 Switches the operation mode of the internal combustion engine E between full cylinder operation outside the idle cylinder region F and partial cylinder operation in the idle cylinder region F based on the determination result. At this time, the lower limit rotational speeds Na and Nb in the fully closed cylinder region Fa and the non-fully closed cylinder region Fb are the fuel cuts when the throttle valve 6 is fully closed and when the throttle valve 6 is not fully closed, respectively. The fuel return is performed in regions other than the idle cylinder regions Fa and Fb, which are engine rotational speed regions lower than the lower limit rotational speeds Na and Nb, by being larger than the subsequent return rotational speeds Nra and Nrb by predetermined values ΔNa and ΔNb. Since the operation is performed in the full-cylinder operation state, the generation of vibration and noise at the time of fuel return is suppressed and the vibration and noise of the internal combustion engine E are reduced as compared with the case where fuel return is performed in the state of partial cylinder operation.

  The lower limit rotational speeds Na and Nb are set based on the return rotational speeds Nra and Nrb that are changed according to the vehicle operating state such as the shift position, thereby taking into consideration the fuel efficiency performance by fuel cut while preventing engine stall. In response to the return rotational speeds Nra and Nrb set in this way, the cylinder resting region F in which the partial cylinder operation is performed can be expanded, and this point can also contribute to the improvement of fuel efficiency.

  The cylinder resting regions Fa and Fb are set according to whether the throttle valve 6 is fully closed or not fully closed. The lower limit rotational speed Na of the fully closed cylinder closing region Fa is the lower limit rotational speed Nb of the non-fully closed cylinder closing region Fb. When the throttle valve 6 is fully closed, the idle cylinder area F is expanded to a lower engine speed area when the throttle valve 6 is fully closed, so that the operation area in the partial cylinder operation is expanded and the fuel efficiency performance is improved. improves.

  The valve deactivation mechanism 1 is a hydraulic mechanism that is driven by hydraulic oil, and the predetermined values ΔNa and ΔNb are set to different values according to the temperature or pressure of the hydraulic oil, so that the valve deactivation mechanism 1 is surely set when fuel returns. In addition, all cylinder operation is possible, and the predetermined values ΔNa and ΔNb can be set as small as possible depending on the temperature or pressure of the hydraulic oil, so that all cylinder operation at the time of fuel recovery is ensured. Since the cylinder deactivation region F in the internal combustion engine E including the valve deactivation mechanism 1 composed of a hydraulic mechanism is expanded, the operation range of the partial cylinder operation is expanded, and fuel efficiency is further improved.

  The valve deactivation mechanism 1 is provided in each of the plurality of cylinders, and the non-operating state and the operating state are sequentially switched according to the rotational position of the crankshaft D. The predetermined values ΔNa and ΔNb are respectively set to the return rotational speed. By setting different values according to Nra and Nrb, the valve deactivation mechanism 1 is in a state in which all cylinders can be reliably operated at the time of fuel return, and the predetermined values ΔNa and ΔNb are set according to the return rotational speeds Nra and Nrb. Therefore, all cylinder operation at the time of fuel return is ensured, and the cylinder deactivation region in the internal combustion engine E including the valve deactivation mechanism 1 that is sequentially switched according to the rotation position of the crankshaft D is ensured. Since F is expanded, the operating range of the partial cylinder operation is expanded, and the fuel efficiency is further improved.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
The fully closed sensor 36 may detect a fully closed position of the throttle valve 6. Further, the internal combustion engine E may be a multi-cylinder internal combustion engine other than the V type or other than the six cylinders.

1 is a schematic view of a variable cylinder internal combustion engine according to the present invention. It is a block diagram which shows the main components of the control apparatus for switching the driving | running form of the internal combustion engine of FIG. It is a figure which shows the map which sets the cylinder deactivation area of the internal combustion engine of FIG. FIG. 2 is a diagram for explaining a relationship between a lower limit rotational speed of a cylinder deactivation region and a return rotational speed at which fuel return is executed in the internal combustion engine of FIG. 1. FIG. 2 is a diagram showing a map for setting a predetermined value corresponding to a difference between a lower limit rotation speed and a return rotation speed in accordance with the temperature of hydraulic oil that operates the valve deactivation mechanism of the internal combustion engine of FIG. 1. FIG. 2 is a diagram showing a map for setting a predetermined value corresponding to a difference between a lower limit rotational speed and a return rotational speed in accordance with the pressure of hydraulic oil that operates the valve deactivation mechanism of the internal combustion engine of FIG. 1. FIG. 2 is a diagram showing a map for setting a predetermined value corresponding to a difference between a lower limit rotational speed and a return rotational speed in accordance with the engine rotational speed of the internal combustion engine of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Valve deactivation mechanism, 2 ... Hydraulic control valve, 3 ... Oil passage, 4 ... Intake device, 5 ... Air cleaner, 6 ... Throttle valve, 7 ... Intake manifold, 8 ... Fuel injection valve, 9 ... Spark plug, 10 ... Exhaust 11 ... Exhaust manifold, 12 ... Electric motor, 13 ..., 14 ..., 20 ... ECU, 21 ... Cylinderless region setting means, 22 ... Determination means, 23 ... Cylinder number control means, 24 ... Fuel control means, 25 ... Spark plug control means, 30 ... operating state detection means, 31 ... vehicle speed sensor, 32 ... accelerator sensor, 33 ... throttle opening sensor, 34 ... rotation speed sensor, 35 ... deceleration detection means, 36 ... full-closed sensor, 37 ... temperature Sensor, 38… Pressure sensor,
E ... Variable cylinder internal combustion engine, D ... Crankshaft, C1-C6 ... Cylinder, Ba, Bb ... Bank, P ... Oil pump, F ... Rest cylinder area, Fo ... Basic cylinder rest area, Fa ... Full cylinder closure cylinder area , Fb: Non-fully closed cylinder region, No, Na, Nb: Lower limit rotational speed, Nra, Nrb: Return rotational speed, ΔNa, ΔNb: Predetermined values.

Claims (3)

A throttle valve for measuring intake air; a rotation speed sensor for detecting engine rotation speed; a cylinder deactivation area setting means for setting a cylinder deactivation area in which a partial cylinder operation in which some cylinders are deactivated; and the rotation speed sensor Determination means for determining whether the engine speed is in the cylinder deactivation region based on the detection result of the engine, cylinder number control means for setting the number of operating cylinders based on the determination result of the determination means, and the part A cylinder deactivation mechanism provided in each cylinder and fuel control means for executing fuel return after fuel cut, and the cylinder number control means controls the cylinder deactivation mechanism so that all cylinders except for the deactivation area are In the variable cylinder internal combustion engine in which the operation mode is switched between the full cylinder operation to be operated and the partial cylinder operation in the cylinder deactivation region,
A variable cylinder internal combustion engine characterized in that a lower limit rotational speed of the idle cylinder region is larger by a predetermined value than a return rotational speed that is an engine rotational speed at the time of fuel return.   2. The variable cylinder internal combustion engine according to claim 1, wherein the cylinder deactivation mechanism is a hydraulic mechanism driven by hydraulic oil, and the predetermined value is set to a different value according to a temperature or pressure of the hydraulic oil. organ. The cylinder deactivation mechanism is provided in each of the plurality of some cylinders, and the non-operating state and the operating state are sequentially switched according to the rotational position of the crankshaft, and the predetermined value is the return rotational speed. 3. The variable cylinder internal combustion engine according to claim 1, wherein the variable cylinder internal combustion engine is set to a different value in accordance with.

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