JP2006322371A - Engine control device, vehicle control device and engine control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sufficiently absorb a vehicle shock caused in transition to fuel cut control or in return from the fuel cut control. <P>SOLUTION: An engine control device of the invention directly controls an intake air quantity to each cylinder by changing a lift of intake valves of a bank on an operation side in transition to cylinder cut-off control or in return from the cylinder cut-off control so that a variation of engine torque is lessened. This allows hardly causing response delay in an intake system, quickly suppressing the engine torque variation and sufficiently absorbing the vehicle shock. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine control device and an engine control method, and more particularly, to an engine control device and an engine control method for mitigating vehicle shocks when shifting to fuel cut control such as reduced cylinder control or returning from fuel cut control.

  Conventionally, for the purpose of reducing exhaust emissions and improving fuel economy, all cylinders of the engine are temporarily cut off when the vehicle is decelerated, etc. Fuel cut control is performed.

  However, at the moment of shifting to such fuel cut control, or at the moment of returning from the fuel cut control, the engine torque changes abruptly, which may give the driver discomfort such as a shock.

Therefore, at the time of shifting to such fuel cut control or returning from the fuel cut control, the opening degree of the throttle valve and the idle speed control valve (hereinafter referred to as “ISCV”) is controlled to reduce the intake air amount to the cylinder. Measures such as adjustment and suppression of rapid fluctuations in engine torque have been taken (see, for example, Patent Document 1).
JP-A-6-193478

  However, since there is a certain distance between the throttle valve or ISCV and the cylinder that actually generates the engine torque, a response delay of the intake system occurs before these valve controls are reflected in the engine control. For this reason, it is difficult to control the amount of intake air to each cylinder at an optimal timing, and there is a problem that the shock of the vehicle cannot be sufficiently mitigated.

  The present invention has been made in view of the above points, and an engine control apparatus and an engine control method that can sufficiently mitigate a vehicle shock that occurs when shifting to fuel cut control or when returning from fuel cut control. The purpose is to provide.

  In the present invention, in order to solve the above-described problem, at least one control at the time of transition to the fuel cut control for shutting off the fuel supply to at least one cylinder of the plurality of cylinders and at the time of transition from the fuel cut control to the normal control Provided is an engine control device that controls the lift amount of a valve of any cylinder to a side that reduces fluctuations in engine torque at the time of transition.

  “Fuel cut control” here means control for temporarily shutting off fuel supply to any one of a plurality of cylinders, and stopping fuel injection to any cylinder in a single or a plurality of banks. Control, and cylinder reduction control for stopping fuel injection to all cylinders of any bank in the plurality of banks (the same applies hereinafter).

  In such an engine control device, when shifting to fuel cut control, when returning from fuel cut control, and preferably both, the lift amount of the valve of one of the cylinders reduces fluctuations in engine torque. It is controlled to the side to do. The cylinder for which the lift amount is controlled may be a fuel cut control or a cylinder related to the return thereof, or may be a cylinder other than that.

  For example, at the time of transition to at least one of the above controls, the lift amount of the intake valve of the cylinder on the operating side is controlled so as to reduce the fluctuation of the engine torque in synchronization with the switching between the fuel supply state and the fuel cut state. May be.

  In this case, since the engine torque decreases when shifting to the fuel cut control, the fluctuation of the engine torque as a whole can be reduced by increasing the lift amount of the intake valve and controlling the engine torque to increase. . Further, since the engine torque increases when returning from the fuel cut control, the overall fluctuation in engine torque can be reduced by reducing the lift amount of the intake valve and controlling the engine torque to decrease.

  For example, when shifting to fuel cut control, the lift amount of the intake valve of the cylinder on the fuel cut side is controlled in advance to be smaller than the lift amount of the intake valve of the cylinder on which the operation is continued. Also good.

  Thus, by reducing the lift amount of the intake valve of the cylinder on the fuel cut side before the fuel cut, the amount of decrease in the intake air amount at the time of the fuel cut is reduced, and sudden changes in engine torque are prevented or suppressed. The

  In the present invention, any one of the transition to the fuel cut control for shutting off the fuel supply to at least one cylinder of the plurality of cylinders and the transition to at least one of the transition from the fuel cut control to the normal control. An engine control method is provided that controls the lift amount of the valve of the cylinder in such a manner as to reduce the fluctuation of the engine torque.

  In such an engine control method, when shifting to the fuel cut control, when returning from the fuel cut control, and preferably both, the lift amount of the valve of any cylinder reduces the fluctuation of the engine torque. It is controlled to the side to do.

  According to the engine control device and the engine control method of the present invention, the valve lift amount of any cylinder is controlled at the time of transition to fuel cut control or at the return from fuel cut control, and suction into the cylinder is performed. Since the air volume is directly controlled, there is almost no response delay in the intake system. For this reason, when the lift amount of the valve is controlled to reduce the fluctuation of the engine torque, the fluctuation of the engine torque is quickly suppressed, and the vehicle shock can be sufficiently mitigated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
In this embodiment, the engine control device of the present invention is applied to a vehicle control device for a vehicle equipped with a continuously variable transmission. FIG. 1 is a block diagram illustrating the configuration of the vehicle control device according to the first embodiment.

  The output shaft of the engine 1 of the vehicle is provided with an oil pump 2 for pumping hydraulic oil from a hydraulic source (not shown), a torque converter 3 for smoothly transmitting the power of the engine 1 to the axle, and a forward / reverse clutch 4 for switching between forward and backward travel of the vehicle. A continuously variable transmission 5 for continuously changing the gear ratio, and a reduction gear 6 for making the rotation direction of the axle coincide with the rotation direction of the output shaft of the engine 1 are sequentially connected. The output of the reduction gear 6 is transmitted to the left and right drive wheels 8 via a differential 7. Further, the engine 1 is provided with a throttle valve 9 that electronically controls the intake air amount based on the depression amount of the throttle pedal.

  The torque converter 3 includes a pump impeller 10 connected to the output shaft of the engine 1, a turbine liner 11 connected to the output shaft of the torque converter 3, a stator 12 that is sandwiched between the stator 12 and changes the internal oil flow, and A lock-up clutch 13 for fastening the pump impeller 10 and the turbine liner 11 under a predetermined condition is provided.

  The continuously variable transmission 5 includes a primary pulley 14 connected to the input shaft, a secondary pulley 15 connected to the output shaft, and a belt 16 stretched between the pulleys, and torque transmitted from the input shaft. Is transmitted to the output shaft. The shift control of the continuously variable transmission 5 is performed by hydraulic control by the hydraulic control device 17. The hydraulic control device 17 performs hydraulic control using the hydraulic oil pumped up by the oil pump 2. Then, the groove width of the primary pulley 14 is changed by hydraulic control, while the clamping force of the secondary pulley 15 to the belt 16 is held by hydraulic control, and the engagement diameter of the belt 16 in each pulley is changed to change the input shaft. The gear ratio, which is the ratio of the number of rotations between the motor and the output shaft, is continuously changed.

  Each control target is controlled by an electronic control unit (hereinafter referred to as “ECU”) mounted on the vehicle. The vehicle control ECU 20 is provided with an engine control unit 21 that controls the engine 1 and a shift control unit 22 that controls the continuously variable transmission 5. Here, the configuration in which each control unit is provided in one ECU is shown, but each control unit is configured as an independent ECU, that is, an engine control ECU and a shift control ECU, via a predetermined communication line. You may be connected so that communication is mutually possible.

FIG. 2 is a schematic configuration diagram showing the configuration of the engine and the intake / exhaust system.
The engine 1 is configured as a V-type 6-cylinder engine, and includes a cylinder block formed in a V shape having a right bank 1R and a left bank 1L. Although not shown, the first cylinder # 1, the third cylinder # 3, the fifth cylinder # 5 are arranged in the right bank 1R, and the second cylinder # 2, the fourth cylinder # 5 are arranged in the left bank 1L. Fourth and sixth cylinders # 6 are arranged. Then, depending on the state of the vehicle, a reduced-cylinder operation that stops the operation of either the right bank 1R or the left bank 1L is possible.

  An intake pipe 31 is connected to the upstream side of the intake and exhaust system of the engine 1, and an exhaust pipe 32 is connected to the downstream side. An air cleaner 33 is provided at the upstream end of the intake pipe 31, and an intake manifold 34 for dividing the intake passage for each cylinder is provided at the downstream end of the right bank 1R and the left bank 1L. The air introduced into the intake pipe 31 via the air cleaner 33 is sucked into each cylinder of each bank through each intake manifold 34. Since the right bank 1R and the left bank 1L are arranged symmetrically in the engine 1 and have substantially the same configuration, the same components are denoted by the same reference numerals and the description thereof is simplified.

  A surge tank 35 is provided at an intermediate portion of the intake pipe 31, and a bypass passage 36 is formed so as to bypass the throttle valve 9 disposed slightly upstream. An ISCV 37 for adjusting the flow rate of air to be bypassed is disposed in the bypass passage 36. During idling, the engine speed is adjusted by controlling the opening of the ISCV 37 to adjust the intake air amount.

  In the intake manifold 34, an injector 41 is disposed in each intake port provided for each cylinder. The injector 41 is supplied with fuel that has been pumped from the fuel tank and pressure-regulated, and is opened by energization control to inject fuel into the intake port. The fuel injected at this time is mixed with intake air introduced from the upstream side to become an air-fuel mixture, and is supplied to the combustion chamber 43 of each cylinder via the intake valve 42.

  A spark plug 44 is disposed in the combustion chamber 43 of each cylinder. The spark plug 44 is applied with a high voltage generated by an igniter 45 integrated with an ignition coil to generate a spark for ignition. By this ignition, the air-fuel mixture in the combustion chamber 43 is combusted, and a rotational driving force is applied to the crankshaft 47 through the piston 46. When the engine 1 is in a predetermined high load state, both the right bank 1R and the left bank 1L are operated to generate a large rotational driving force. On the other hand, when the engine 1 is in a predetermined low load state, the reduced cylinder operation is performed. Thus, the operation of one bank is stopped to improve fuel efficiency. Exhaust gas generated by the combustion is discharged from each cylinder through the exhaust valve 48.

  The exhaust pipe 32 is branched on the upstream side thereof, and an exhaust manifold is connected to the exhaust pipe 32 by joining the exhaust passages of the respective cylinders of the right bank 1R and the left bank 1L to the upstream ends thereof. 49 are provided. A catalytic converter 50 for purifying exhaust gas is disposed downstream of the junction of the exhaust pipe 32. The catalytic converter 50 accommodates a three-way catalyst that simultaneously promotes oxidation of unburned components in exhaust gas and reduction of nitrogen oxides. Exhaust gas discharged from the combustion chamber 43 is led to the exhaust pipe 32 through the exhaust manifold 49, purified by the catalytic converter 50, and sent to a muffler (not shown).

  Further, an air flow meter 51 integrated with an intake air temperature sensor is provided at the most upstream portion of the intake pipe 31 so that the intake air amount and the intake air temperature can be detected. A throttle opening sensor 52 for detecting the opening of the throttle valve 9 is provided in the vicinity of the throttle valve 9 of the intake pipe 31.

  Further, the cylinder block of the engine 1 is provided with a water temperature sensor 53 for detecting the temperature of engine cooling water and a knock sensor 54 for detecting knocking for each bank. Further, the igniter 45 is provided with a cam position sensor 55 for performing cylinder discrimination by detecting a camshaft displacement angle provided for each cylinder and adjusting a valve timing described later. Has been. Further, a crank angle sensor 56 that generates a crank angle signal at every predetermined crank angle accompanying the rotation of the crankshaft 47 is disposed in the vicinity of the crankshaft 47 in order to calculate the engine speed.

  Further, an air-fuel ratio sensor 57 is provided in the exhaust pipe 32, and fuel injection control is performed by air-fuel ratio feedback control that brings the air-fuel ratio detected by the air-fuel ratio sensor 57 closer to the theoretical air-fuel ratio.

  Further, in the engine 1, in order to adjust the opening / closing timing of the intake valve 42 and the exhaust valve 48 to adjust the overlap period in which both valves are opened simultaneously, each of the right bank 1R and the left bank 1L is driven by hydraulic pressure. Variable valve timing mechanisms (hereinafter referred to as “VVT”) 61 and 62 are provided. That is, by changing the displacement angle of the camshaft of the VVT 61 provided on the intake side of each bank with respect to the rotation of the crankshaft 47, the valve timing of the intake valve 42 can be continuously changed to the advance side or the retard side. It is like that. Further, by changing the displacement angle of the camshaft of the VVT 62 provided on the exhaust side of each bank with respect to the rotation of the crankshaft 47, the valve timing of the exhaust valve 48 can be continuously changed to the advance side or the retard side. It is like that. Thereby, the overlap period during which the intake valve 42 and the exhaust valve 48 are simultaneously opened is adjusted. The VVTs 61 and 62 operate when the corresponding hydraulic control valve is driven and controlled based on the output value of the cam position sensor 55.

  Further, the intake valve 42 and the exhaust valve 48 are configured so that the lift amount (that is, the valve opening degree) of the valve can be controlled by a predetermined lift amount adjusting mechanism. FIG. 3 is an explanatory diagram showing a schematic configuration of the lift amount adjusting mechanism of the intake valve 42. FIG. 4A shows a large lift mode in which the lift amount of the valve becomes large, and FIG. 4B shows a small lift mode in which the lift amount of the valve becomes small. The lift amount of the valve can be appropriately adjusted between the large lift mode and the small lift mode. Note that the lift amount adjustment mechanism of the exhaust valve 48 is substantially the same as that of the intake valve 42, and therefore the description thereof is omitted.

  The intake valve 42 is converted into a swinging motion of the relay arm 64 and the rocker arm 65 in turn by rotating the cam shaft 63 in synchronization with the crankshaft 47, and is pushed in the direction of its own axis by the rocker arm 65. It is configured to move and open.

  That is, the relay arm 64 is supported so as to be swingable around a swing shaft (not shown) in the vicinity of the central portion thereof. A cam 67 that comes into contact with the outer peripheral surface of the cam 66 provided on the cam shaft 63 is provided slightly below the center portion of the relay arm 64, and a roller provided at the center portion of the rocker arm 65 is provided at the lower end portion. A cam portion 69 is provided in contact with 68. Furthermore, a cam shaft 70 that is rotationally driven by a driving motor (not shown) is provided above the relay arm 64. The cam shaft 70 is provided with a cam 71, and the outer peripheral surface thereof is in contact with a roller 72 provided at the end of the relay arm 64.

  For this reason, when the cam 66 is rotated by the rotation of the cam shaft 63, the relay arm 64 swings left and right together with the cam 67. At this time, since the cam portion 69 moves left and right, the roller 68 moves up and down according to the shape of the lower end surface of the cam portion 69. As a result, the rocker arm 65 swings up and down, and the intake valve 42 moves up and down.

  When the cam 71 rotates due to the rotation of the cam shaft 70, the position of the support shaft of the relay arm 64 moves, and the contact position between the cam 71 and the roller 72 changes. Thereby, the width of the vertical movement of the intake valve 42 can be changed. In the present embodiment, the lift amount of the intake valve 42 is appropriately changed between the large lift mode shown in FIG. 5A and the small lift mode shown in FIG. The engine torque generated by controlling the amount of intake air to the cylinder can be adjusted.

FIG. 4 is a block diagram showing the vehicle control ECU and its input / output.
The vehicle control ECU 20 includes a CPU (Central Processing Unit) that executes various arithmetic processes, a ROM (Read Only Memory) that stores various control arithmetic programs and data, and a RAM (Numerical value and flags of arithmetic processes that are stored in a predetermined area. Random Access Memory), EEPROM (Electronically Erasable and Programmable Read Only Memory), which is a non-volatile storage device that stores the results of arithmetic processing, and A / D (Analog / Digital) that converts input analog signals into digital signals ) A converter, an input / output interface for inputting / outputting various digital signals, and a bus line to which these devices are connected, respectively.

  The vehicle control ECU 20 takes in output signals from various sensors that detect the state of the engine 1 and outputs drive signals to various actuators provided in the engine 1. That is, the vehicle control ECU 20 includes the intake pipe 31 in addition to the air flow meter 51, the throttle opening sensor 52, the water temperature sensor 53, the knock sensor 54, the cam position sensor 55, the crank angle sensor 56, and the air-fuel ratio sensor 57 described above. An intake pressure sensor 81 for detecting the internal pressure, an accelerator opening sensor 82 for detecting the depression amount of the accelerator pedal, a vehicle speed sensor 83 for detecting the vehicle speed from the rotation of the vehicle drive shaft, and the input shaft rotational speed of the continuously variable transmission 5 A primary rotation sensor 84 to detect, a secondary rotation sensor 85 to detect the rotational speed of the output shaft of the continuously variable transmission 5, an oil temperature sensor 86 to detect the temperature of hydraulic oil, and a hydraulic pressure (belt clamping pressure) in the secondary pulley. A belt clamping pressure sensor 87, a shift position sensor 88 for detecting a current shift position, an ignition switch 89, etc. Sensors and switches of is connected.

  Also, the vehicle control ECU 20 pumps fuel from the injectors 41 (INJ1 to INJ6), igniters 45 (IGT1 to IGT6) and fuel tanks of the cylinders (# 1 to # 6) of each bank and supplies the fuel to the injectors 41. A pump 91, a throttle drive motor 92 for opening and closing the throttle valve 9, a starter motor 93 for cranking the engine 1, a VVT hydraulic control valve 94 for driving VVTs 61 and 62, and the cam shaft 70 of the lift amount adjusting mechanism described above are rotated. Various actuators such as a driving motor 95 for driving are connected. The vehicle control ECU 20 performs a predetermined vehicle control process according to a control program stored in the ROM.

  Next, the engine control method of the present embodiment will be described. The engine control method of the present embodiment is mainly characterized by engine control at the time of transition from normal operation to reduced-cylinder operation and at the time of return from reduced-cylinder operation to normal operation, and other controls are general. This is the same as the engine control. For this reason, the following description will focus on engine control at the time of switching between this reduced-cylinder operation and normal operation. Here, a description will be given by taking as an example a scene in which the reduced cylinder control is executed to improve fuel efficiency when the vehicle is in a low load state.

  FIG. 5 is a timing chart showing this engine control method. In the figure, the horizontal axis represents the passage of time, the vertical axis represents the operating state of the engine 1 from the upper stage, the lift amount of the intake valve 42 on the non-reducing cylinder side (that is, the operating side), and the engine torque according to the present embodiment. Changes and engine torque changes according to the prior art as comparative examples are shown.

  In the engine 1, a timing of shifting from a normal operation in which both the right bank 1R and the left bank 1L are operated to a reduced cylinder operation in which the fuel is cut for the cylinders # 2, # 4, and # 6 and the left bank 1L is stopped. In synchronization with the control, the lift amount of the intake valve 42 of the cylinders # 1, # 3, # 5 of the right bank 1R on the operating side is controlled to be larger than that in the normal operation. The lift amount of the intake valve 42 is adjusted by controlling the lift amount adjusting mechanism described above.

  That is, the engine torque as a whole decreases during the transition from the normal operation to the reduced cylinder operation, but the engine torque increases by increasing the intake air amount by increasing the lift amount of the intake valve 42 on the operating side. By controlling so as to prevent a sudden decrease in the engine torque as a whole.

  In the illustrated comparative example, the engine torque fluctuates suddenly when switching from normal operation to reduced-cylinder operation, but according to the present embodiment, fluctuations in engine torque at the time of switching are suppressed. I understand.

  Further, in the engine 1, after the fuel injection is resumed for the cylinders # 2, # 4, and # 6, the operation of the right bank 1R that continues operation is synchronized with the return timing to the normal operation in which the left bank 1L operates. Control is performed so that the lift amount of the intake valves 42 of the cylinders # 1, # 3, and # 5 is returned to the lift amount during normal operation.

  That is, when returning from the reduced-cylinder operation to the normal operation, the engine torque increases as a whole, but the engine torque decreases by decreasing the lift amount of the intake valve 42 on the operating side and decreasing the intake air amount. By controlling in the direction, the rapid increase in engine torque as a whole is prevented.

  Also in this case, in the illustrated comparative example, the engine torque fluctuates suddenly when switching from reduced-cylinder operation to normal operation, but according to the present embodiment, fluctuations in engine torque at the time of switching are suppressed. I understand that.

  Next, a specific processing flow of the above-described engine control will be described. FIG. 6 is a flowchart showing the flow of the engine torque control process executed by the vehicle control ECU during the reduced cylinder control. Hereinafter, the flow of this process will be described using step numbers (hereinafter referred to as “S”).

  The vehicle control ECU 20 first determines whether or not a predetermined reduction cylinder condition for shifting from normal operation to reduction cylinder operation is satisfied (S1). The cylinder reduction condition is set in advance. For example, the engine speed calculated based on the output of the crank angle sensor 56 is a predetermined value or less, and the vehicle speed calculated based on the output of the vehicle speed sensor 83 is predetermined. It can be a condition that the accelerator pedal is not depressed based on the output of the accelerator opening sensor 82.

  If it is determined that the reduced cylinder condition is satisfied (S1: YES), the drive motor 95 is driven to drive the intake valve 42 of each cylinder on the operating side (right bank 1R side in the present embodiment). The lift amount is controlled to be larger than that during normal operation (S2). At the same time, the cylinder reduction control is executed by cutting the fuel to the left bank 1L (S3).

  After shifting to the reduced cylinder control in this way, it is determined whether or not a predetermined return condition for returning from the reduced cylinder operation to the normal operation is satisfied (S4). The return condition is also set in advance. For example, a condition can be set when at least one of the above-described reduced cylinder conditions is not satisfied.

  If it is determined that the return condition is satisfied (S4: YES), the intake motor on the side (in the present embodiment, the right bank 1R side) that drives the drive motor 95 and continues to operate is determined. The lift amount 42 is controlled to return to the lift amount during normal operation (S5). At the same time, fuel injection to the left bank 1L is resumed and normal control is executed (S6).

  As described above, in the engine control apparatus according to the present embodiment, each cylinder is changed by changing the lift amount of the intake valve 42 of the operating bank when shifting to the reduced cylinder control or when returning from the reduced cylinder control. The amount of intake air to the engine is directly controlled so that fluctuations in engine torque are reduced. For this reason, the response delay of the intake system hardly occurs, the fluctuation of the engine torque is quickly suppressed, and the shock of the vehicle can be sufficiently mitigated.

  In this embodiment, a vehicle having a plurality of banks and stopping one of the banks and shifting to a reduced-cylinder operation when a predetermined reduced-cylinder condition is satisfied has been described, but the engine control method of the present invention Can be applied to a vehicle that does not perform such reduced cylinder control. In other words, the present invention can be applied to a vehicle in which fuel cut control for cutting off fuel supply to at least one of the plurality of cylinders is performed without performing cylinder reduction control for each bank. In this case, the lift amount of the intake valve on the operating side is controlled so as to reduce the fluctuation of the engine torque in synchronization with the transition to the fuel cut control and the return from the fuel cut control.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The present embodiment is the same as the first embodiment except that the processing portion of the engine control executed when switching between normal operation and reduced-cylinder operation is different. For this reason, description of the same parts as those in the first embodiment will be omitted.

  FIG. 7 is a timing chart illustrating an engine control method according to the second embodiment. In the figure, the horizontal axis represents the passage of time, and the vertical axis represents the operating state of the engine 1 from the upper stage, the lift amount of the intake valve 42 on the non-cylinder side (that is, the operating side), and the reduced cylinder side (that is, the inactive side). The lift amount of the intake valve 42 and the engine torque change according to the present embodiment are respectively shown. In the figure, the change in engine torque according to the prior art as a comparative example is omitted.

  In the engine 1, the normal operation in which both the right bank 1 </ b> R and the left bank 1 </ b> L are operating immediately before the shift to the reduced cylinder operation in which the fuel is cut for the cylinders # 2, # 4, and # 6 and the left bank 1 </ b> L is stopped. In addition, the lift amount of the intake valve 42 of the cylinder of the idle side bank is controlled in advance so as to be smaller than the lift amount of the intake valve 42 of the cylinder of the operating side bank. Then, in synchronization with the timing of shifting to the reduced cylinder operation, the lift amount of the intake valve 42 of the cylinders # 1, # 3, # 5 of the right bank 1R on the operating side is slightly larger than that in the normal operation. Control.

  That is, the engine torque at the time of actual control switching while reducing the lift amount of the intake valve 42 of the cylinder in the idle side bank and reducing the engine torque slightly before a predetermined time before shifting from the normal operation to the reduced cylinder operation. Prevents a sudden drop in Further, at the time of control switching, from the same idea as in the first embodiment, by increasing the lift amount of the intake valve 42 of the operating side bank and increasing the intake air amount, the engine torque is controlled to increase. The engine torque as a whole is prevented from suddenly decreasing. In this embodiment, since the engine torque is lowered by reducing the lift amount of the intake-side intake valve 42 in advance, the degree of increase in the lift amount of the intake-side intake valve 42 is the first embodiment. It can be made smaller than in the case of.

It can be seen that the variation of the engine torque at the time of switching of control is also suppressed by this embodiment.
Further, in the engine 1, the lift amount of the intake valve 42 of the right bank 1 </ b> R that continues to operate and the left bank 1 </ b> L that has been stopped are synchronized with the return timing to the normal operation in which the left bank 1 </ b> L operates thereafter. The lift amount of each intake valve 42 is controlled so as to return to the lift amount during normal operation.

  According to the engine control apparatus of the present embodiment, especially when shifting to the cylinder reduction control, the lift amount of the intake valve 42 of the pause side bank is controlled in advance so that the fluctuation of the engine torque when the control is switched I try to make it smaller. For this reason, the shock of the vehicle can be quickly and sufficiently alleviated.

  In this embodiment, the vehicle that shifts to the reduced cylinder operation according to the predetermined condition has been described. However, the fuel supply to at least one of the plurality of cylinders is cut off without performing the reduced cylinder control for each bank. The present invention can be applied to a vehicle in which fuel cut control is performed. In this case, at the time of shifting to the fuel cut control, the lift amount of the intake side intake valve is controlled in advance to reduce the fluctuation of the engine torque.

  Further, in the present embodiment, as in the first embodiment, the lift amount of the intake valve 42 of the operating bank is increased when switching to the reduced cylinder operation, but the engine is controlled by the lift amount control of the idle bank side. This can be omitted if torque fluctuations are sufficiently reduced.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. Note that the engine control method of the present embodiment is implemented in combination with the engine control process of the first and second embodiments, but the processing portion similar to that of the first or second embodiment is described. Description is omitted.

  FIG. 8 is a timing chart showing an engine control method according to the third embodiment. In the figure, the horizontal axis represents the passage of time, and the vertical axis represents the operating state of the engine 1 from the upper stage, the exhaust valve timing of the operating exhaust valve 48, the intake valve timing of the operating intake valve 42, and the present embodiment. Represents the change in engine torque due to.

  In the engine 1, immediately before the transition from the normal operation to the reduced-cylinder operation, the VVT hydraulic control valve 94 is driven in advance to retard the exhaust valve timing of the operating bank and advance the intake valve timing of the operating bank. By controlling, the overlap period in which the intake valve 42 and the exhaust valve 48 open simultaneously is lengthened. As a result, the so-called internal EGR is increased, the engine torque is reduced in advance by a predetermined amount, and the reduction amount of the engine torque when switching to the reduced cylinder operation is reduced.

  In addition, when returning from reduced-cylinder operation to normal operation, the exhaust valve timing of the operating bank is retarded and the intake valve timing of the operating bank is advanced while synchronizing with the switching of the control. The overlap period is lengthened. This prevents a sudden increase in engine torque.

Thereby, the fluctuation | variation of an engine torque can be suppressed further and the shock of a vehicle can fully be relieved.
In this embodiment, the overlap period is lengthened by adjusting both the intake valve timing and the exhaust valve timing of the operating bank, but either one may be adjusted to lengthen the overlap period. Good.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. Note that the engine control method of the present embodiment is also implemented in combination with the engine control process of the first and second embodiments, but the processing parts similar to those of the first or second embodiment will be described. Is omitted.

  FIG. 9 is a timing chart showing an engine control method according to the fourth embodiment. In the figure, the abscissa represents the passage of time, and the ordinate represents the operating state of the engine 1, the ignition timing of the operating bank, the ignition timing of the idle bank, and the change in engine torque according to the present embodiment from the top. ing.

  In the engine 1, immediately before the transition from the normal operation to the reduced cylinder operation, the ignition timing of the stop side bank (the left bank 1L in the present embodiment) is retarded in advance to slightly lower the engine torque, and when the control is switched. The engine torque is increased by controlling the ignition timing of the operating bank (right bank 1R in this embodiment) to advance. This prevents a sudden decrease in the engine torque as a whole.

Further, when returning from the reduced-cylinder operation to the normal operation, the ignition timing of the operating bank and the inactive bank is returned to the normal operation state in synchronization with the switching of the control.
Thereby, the fluctuation | variation of an engine torque can be suppressed and the shock of a vehicle can fully be relieved.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. Note that the engine control method of the present embodiment is a combination of the engine control and the ignition timing control of the first embodiment, but the same processing parts as those of the first embodiment will be described. Omitted.

  FIG. 10 is a timing chart illustrating an engine control method according to the fifth embodiment. In the figure, the horizontal axis represents the passage of time, and the vertical axis represents the operating state of the engine 1, the ignition timing of the operating bank, the lift amount of the intake valve of the operating bank, and the change in engine torque according to this embodiment. Respectively. FIG. 11 is a state transition diagram of the vehicle corresponding to the engine control of FIG. (A) represents the state at the time of transition from normal operation to reduced-cylinder operation, and (B) represents the state at the time of return from reduced-cylinder operation to normal operation. In these drawings, the horizontal axis represents the lift amount of the intake valve of the operating bank, and the vertical axis represents the change in engine torque. In the following, description will be given based on FIG. 10 with reference to FIG. 11 as appropriate.

As shown in FIG. 10, in the engine 1, when the control is switched from the normal operation to the reduced-cylinder operation, the ignition timing is retarded in advance and the engine torque is slightly reduced (state (1)).
Then, at the moment of switching to the reduced cylinder operation, the lift amount of the intake valve 42 is increased so as to suppress the decrease in engine torque, and the ignition timing is previously retarded (or advanceable) by the advance. Control (state (2)). As a result, as shown in FIG. 11A, the engine torque is greatly reduced as indicated by a two-dot chain line arrow in order to shift to the reduced cylinder operation under normal circumstances, but only to the extent indicated by the solid line arrow.

  At the moment of switching from the reduced cylinder operation to the normal operation, the lift amount of the intake valve 42 is reduced to reduce the intake air amount (state (3)), and the ignition timing is retarded to increase the engine torque. (State (4)). As a result, as shown in FIG. 11B, it is possible to return to normal operation while keeping the fluctuation range of the engine torque small.

  In this way, by performing cooperative control of lift control and ignition timing control of the intake valve 42 at the time of switching between reduced-cylinder operation and normal operation, the fluctuation range of the engine torque can be reduced.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. Note that the engine control method of the present embodiment is also implemented in combination with the engine control process of the first and second embodiments, but the processing parts similar to those of the first or second embodiment will be described. Is omitted.

  FIG. 12 is a timing chart showing an engine control method according to the sixth embodiment. In the figure, the horizontal axis represents the passage of time, and the vertical axis represents the operating state of the engine 1 from the upper stage, the fastening force of the lockup clutch 13 of the torque converter 3, and the belt clamping pressure of the continuously variable transmission 5, respectively. .

  The engine 1 is controlled so that the fastening force of the lockup clutch 13 is reduced and the belt clamping pressure of the continuously variable transmission 5 is reduced at the timing of control switching between normal operation and reduced cylinder operation.

As a result, a slip of the vehicle drive system can be generated when the control is switched, and a shock to the vehicle due to a sudden change in engine torque can be prevented or suppressed.
In the present embodiment, the continuously variable transmission 5 adjusted by the engagement force of the lockup clutch 13 adjusted by the energization control to the lockup solenoid (not shown) and the energization control to the belt clamping solenoid (not shown). Although an example in which the belt clamping pressure is controlled to be simultaneously reduced is shown, only one of these may be implemented.

  In each of the above embodiments, the engine control for the vehicle equipped with the continuously variable transmission 5 is shown. However, except for the sixth embodiment, the engine control is also applied to the vehicle equipped with the multistage automatic transmission. It is possible. In this case, it is preferable to execute the shift control in synchronization with the timing of shifting to the reduced cylinder operation or the timing of returning from the reduced cylinder operation. For example, the shift position is switched from the 5th speed to the 4th speed at the same time as the shift from the normal operation to the reduced cylinder operation, and the shift position is switched from the 4th speed to the 5th speed at the same time as the return from the reduced cylinder operation to the normal operation. That is, a shock is generated in the vehicle during the shift control by the multi-stage automatic transmission. Therefore, by making the shift timing coincide with the switching timing between the reduced-cylinder operation and the normal operation, the shock at the switching can be canceled out. In this case, it is possible to prevent the driver from being shocked unexpectedly, and to reduce discomfort.

It is a block diagram showing the composition of the vehicle control device concerning a 1st embodiment. It is a schematic block diagram showing the structure of an engine and an intake / exhaust system. It is explanatory drawing showing schematic structure of the lift amount adjustment mechanism of an intake valve. It is a block diagram showing vehicle control ECU and its input-output. It is a timing chart showing an engine control method. It is a flowchart showing the flow of the process of the engine torque control which vehicle control ECU performs in the case of cylinder reduction control. It is a timing chart showing the engine control method concerning a 2nd embodiment. It is a timing chart showing the engine control method concerning a 3rd embodiment. It is a timing chart showing the engine control method concerning a 4th embodiment. It is a timing chart showing the engine control method concerning a 5th embodiment. It is a state transition diagram of the vehicle corresponding to the engine control of FIG. It is a timing chart showing the engine control method concerning a 6th embodiment.

Explanation of symbols

1 Engine 1R Right bank 1L Left bank 3 Torque converter 5 Continuously variable transmission 13 Lock-up clutch 16 Belt 20 Vehicle control ECU
42 Intake valve 48 Exhaust valve 61, 62 Variable valve timing mechanism

Claims (11)

  The lift of the valve of any cylinder at the time of transition to the fuel cut control for shutting off the fuel supply to at least one cylinder of the plurality of cylinders and at least one of the control transitions from the fuel cut control to the normal control An engine control device that controls the amount to a side that reduces fluctuations in engine torque.   The lift amount of the intake valve of the cylinder on the operating side is controlled to reduce the fluctuation of the engine torque in synchronization with the switching between the fuel supply state and the fuel cut state at the time of the transition to the at least one control. The engine control device according to claim 1.   When shifting to the fuel cut control, the lift amount of the intake valve of the cylinder on the fuel cut side is controlled in advance so as to be smaller than the lift amount of the intake valve of the cylinder on which the operation is continued. The engine control device according to claim 1. A plurality of banks are provided to control an engine capable of shifting from normal operation to reduced-cylinder operation by cutting fuel to the cylinder of any bank,
The engine control apparatus according to claim 1, wherein the fuel cut control is executed for shifting from the normal operation to the reduced-cylinder operation. In each of the plurality of banks, a variable valve timing mechanism that adjusts the opening / closing timing of at least one of the intake valve and the exhaust valve is controlled,
5. When shifting to the reduced-cylinder operation, the variable valve timing mechanism is controlled in advance so as to increase the overlap period in which the intake valve and the exhaust valve are opened simultaneously. Engine control device.   5. The ignition timing of the bank on the side to be stopped in advance is retarded and the ignition timing of the bank on which the operation is continued is advanced when shifting to the reduced cylinder operation. Engine control device.   5. The engine according to claim 4, wherein fluctuations in the engine torque at the time of switching between the normal operation and the reduced cylinder operation are reduced by cooperatively controlling the lift amount of the valve and the ignition timing. Control device. An engine control device according to claim 4,
Furthermore, it is configured to control the continuously variable transmission,
A vehicle control device that controls the engagement force of the lockup clutch to be small at a timing of shifting to the reduced cylinder operation or a timing of returning from the reduced cylinder operation. An engine control device according to claim 4,
Furthermore, it is configured to control the continuously variable transmission,
The vehicle control device according to claim 1, wherein the belt clamping pressure of the continuously variable transmission is controlled to be small at a timing when shifting to the reduced-cylinder operation or a timing when returning from the reduced-cylinder operation. An engine control device according to claim 4,
Furthermore, it is configured to control a multi-stage automatic transmission,
A vehicle control device that performs shift control in synchronization with a timing of shifting to the reduced-cylinder operation or a timing of returning from the reduced-cylinder operation. The lift of the valve of any cylinder at the time of transition to the fuel cut control for shutting off the fuel supply to at least one cylinder of the plurality of cylinders and at least one of the control transitions from the fuel cut control to the normal control An engine control method characterized in that the amount is controlled so as to reduce fluctuations in engine torque.

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