Control device for vehicle

Abstract

To suppress occurrence of excessive rotation in a power generator.SOLUTION: A control device 90 controls a vehicle 500 including: an engine 10 having a VVT mechanism 17 for adjusting opening / closing timing of an intake valve 15; and a first MG 71 capable of generating electric power by using power of the engine 10. In the case where the first MG 71 is controlled while limit torque is defined as target torque, calculation and storage of an adjustment value for adjusting the opening / closing timing of the intake valve 15 are repeated. When actual engine torque is larger than the target engine torque, a value obtained through timing delay correction of a previously calculated adjustment value only by a first crank angle is calculated as a new adjustment value. When the actual engine torque is smaller than the target engine torque, a value obtained through timing advance correction of the previously calculated adjustment value only by a second crank angle is calculated as a new adjustment value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] The vehicle disclosed in Patent Document 1 includes an engine, a generator, an electric motor, drive wheels, and a planetary gear mechanism. The engine, generator, and drive wheels are connected to one another via the planetary gear mechanism. The planetary gear mechanism distributes engine power to the generator and drive wheels. The generator generates electricity by receiving power from the engine. The drive wheels rotate by receiving power from the engine and power from the electric motor.

[0003] In the above-described vehicle, the magnitude of torque that can be requested from the generator may be limited in consideration of the generator's power generation capacity, which is determined by the generator's specifications, etc. When the torque that can be requested from the generator is limited, the torque of the engine that powers the generator is also limited. When such a limit is imposed, the control device of the above-described vehicle feedback controls the engine so as to maintain a target engine speed defined under the limit. Here, the internal combustion engine of Patent Document 1 is equipped with a variable valve timing mechanism that adjusts the opening and closing timing of the intake valve. The intake valve is located close to the cylinder. When the opening and closing timing of the intake valve is changed in consideration of the intake valve's installation position, the amount of air flowing into the cylinder, and therefore the engine torque, responds quickly to the change. Taking these characteristics into account, when the control device feedback controls the engine in relation to the limit on the generator's torque, it essentially feedback controls the opening and closing timing of the intake valve so as to eliminate the difference between the target engine speed and the actual engine speed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-078760 Summary of the Invention [Problem to be solved by the invention]

[0005] When the intake valve opening / closing timing is feedback-controlled, as in the technology of Patent Document 1, the actual engine speed fluctuates around a target engine speed due to the characteristics of the feedback control. During this fluctuation, the actual engine speed may exceed the target engine speed. In this case, the generator speed increases along with the engine speed, resulting in an increase in the amount of power generated by the generator, which should have been suppressed by imposing torque restrictions on the generator. This can result in an overspeed state, where the generator generates excessive power. [Means for solving the problem]

[0006] A vehicle control device for solving the above problems has as its control target a vehicle equipped with an engine having a variable valve timing mechanism that adjusts the opening and closing timing of an intake valve, a generator capable of generating electricity using power from the engine, a planetary gear mechanism that distributes power among the engine, the generator, and drive wheels, and an electric motor that powers the drive wheels, and controls the engine with a target engine torque calculated based on a running state of the vehicle, and executes limit control that controls the generator with a predetermined limit torque as a target torque, and during execution of the limit control, performs a first process that calculates an adjustment value for adjusting the opening and closing timing based on a difference between an actual engine torque and the target engine torque, and a second process that calculates an adjustment value for adjusting the opening and closing timing based on the difference between the actual engine torque and the target engine torque. and a third process for controlling the variable valve timing mechanism so that the actual opening / closing timing coincides with an adjustment timing obtained by adjusting a base timing according to an operating state of the engine using the latest adjustment value stored in the second process. In the first process, if the actual engine torque is greater than the target engine torque, a value obtained by retarding the previously calculated adjustment value by a predetermined first crank angle is calculated as a new adjustment value, and if the actual engine torque is smaller than the target engine torque, a value obtained by advancing the previously calculated adjustment value by a predetermined second crank angle is calculated as a new adjustment value. [Effects of the Invention]

[0007] The above technical concept can prevent the generator from over-rotating. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Figure 2] FIG. 2 is a diagram showing a schematic diagram of a change in the opening and closing timing. [Figure 3] FIG. 3 is a diagram showing a schematic representation of the update map. [Figure 4]FIG. 4 is a flowchart showing the contents of the processing routine. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Overall structure> An embodiment of a vehicle control device will be described below with reference to the drawings. As shown in Fig. 1, a hybrid vehicle (hereinafter referred to as a vehicle) 500 includes an engine 10, a first motor generator (hereinafter referred to as a first MG) 71, a second motor generator (hereinafter referred to as a second MG) 72, a PCU 200, and a battery 78. The engine 10, the first MG 71, and the second MG 72 are drive sources for the vehicle 500. The first MG 71 and the second MG 72 exchange electric power with the battery 78 via the PCU 200. The PCU 200 includes a step-up / step-down converter, an inverter that converts DC to AC, and the like.

[0010] The vehicle 500 is equipped with a planetary gear mechanism 40. The planetary gear mechanism 40 is equipped with a sun gear 41 which is an external gear, a ring gear 42 which is an internal gear, a plurality of pinion gears 43 located between the sun gear 41 and the ring gear 42, and a carrier 44. The sun gear 41 rotates on its axis. The ring gear 42 rotates coaxially with the sun gear 41. Each pinion gear 43 is meshed with both the sun gear 41 and the ring gear 42, and is supported by the carrier 44 in a state where it can rotate on its axis and revolve around the sun gear 41. The carrier 44 rotates coaxially with the sun gear 41 as the pinion gears 43 revolve.

[0011] The sun gear 41 is connected to the rotor of the first MG 71. The carrier 44 is connected to the crankshaft 34 of the engine 10. The ring gear 42 is connected to the drive shaft 60. The drive shaft 60 is connected to left and right drive wheels 62 via a differential gear 61. With this connection, the planetary gear mechanism 40 distributes power among the engine 10, the first MG 71, and the drive wheels 62. For example, when the crankshaft 34 of the engine 10 inputs torque to the carrier 44, the planetary gear mechanism 40 distributes that torque to the sun gear 41 and the ring gear 42. The torque distributed to the sun gear 41 rotates the rotor of the first MG 71. At this time, the first MG 71 functions as a generator. That is, the first MG 71 generates electricity using the power of the engine 10. On the other hand, when the first MG 71 is made to function as an electric motor, the torque of the rotor of the first MG 71 is input to the crankshaft 34 via the sun gear 41 and thus the carrier 44.

[0012] The rotor of the second MG 72 is connected to the drive shaft 60 via the reduction gear mechanism 50. The second MG 72 functions as an electric motor that provides power to the drive wheels 62, and also functions as a generator that generates electricity through regenerative braking when the vehicle 500 is decelerating.

[0013] In this embodiment, the positive and negative torques of the MGs 71, 72 are handled as follows: For example, with respect to the first MG 71, the torque when the first MG 71 functions as an electric motor is taken as a positive value, and the torque when the first MG 71 functions as a generator is taken as a negative value.

[0014] <Engine> The engine 10 has a plurality of cylinders 30, a plurality of pistons 33, and a crankshaft 34. Note that FIG. 1 shows only one cylinder 30. As with the cylinders 30, FIG. 1 also shows only one of each component for each cylinder 30, such as the piston 33. The cylinders 30 are spaces defined in the engine body 10A. In the cylinders 30, a mixture of fuel and intake air is burned by ignition from a spark plug 32. A piston 33 is provided for each cylinder 30. The piston 33 is located within the cylinder 30. The piston 33 reciprocates within the cylinder 30 in response to the combustion of the mixture. The crankshaft 34 rotates in response to the reciprocating movement of the piston 33.

[0015] The engine 10 has an intake passage 11. The intake passage 11 is connected to each cylinder 30. The intake passage 11 is a passage for introducing intake air into each cylinder 30. A throttle valve 14 for adjusting the amount of intake air, and an injector 31 for each cylinder 30 for supplying fuel to each cylinder 30 are provided midway in the intake passage 11.

[0016] The engine 10 includes multiple intake valves 15, an intake camshaft 16, and a variable valve timing mechanism (hereinafter referred to as a VVT mechanism) 17. An intake valve 15 is provided for each cylinder 30. The intake valve 15 is located at a connection port of the intake passage 11 to the cylinder 30. The intake valve 15 opens and closes the connection port of the intake passage 11 as the intake camshaft 16 rotates. The intake camshaft 16 rotates in conjunction with the crankshaft 34. The VVT ​​mechanism 17 adjusts the opening and closing timing of the intake valves 15 by changing the relative phase of the intake camshaft 16 with respect to the crankshaft 34. As shown in FIG. 2, when adjusting the opening and closing timing of the intake valves 15, the VVT ​​mechanism 17 advances or retards both the opening and closing timing of the intake valves 15 as a set. An advancement refers to moving the crank angle backward relative to a specific crank angle, while a retardation refers to the opposite. The crank angle is the rotation angle of the crankshaft 34. In this embodiment, even when the opening and closing timing of the intake valve 15 is changed, the waveform of the change in the opening degree of the intake valve 15, i.e., the amount of rotation of the crankshaft 34 from the opening to the closing of the intake valve 15, and the maximum opening degree are maintained constant. The VVT ​​mechanism 17 is, for example, an electric type driven by an electric motor.

[0017] As shown in Fig. 1, the engine 10 includes an exhaust passage 21 and a plurality of exhaust valves 25. The exhaust passage 21 is connected to each cylinder 30. The exhaust passage 21 is a passage for discharging exhaust gas from each cylinder 30. An exhaust valve 25 is provided for each cylinder 30. The exhaust valve 25 opens and closes a connection port of the exhaust passage 21 with the cylinder 30.

[0018] The engine 10 is equipped with various sensors. For example, the engine 10 is equipped with a crank angle sensor 36, a cam angle sensor 18, and an air flow meter 19. The crank angle sensor 36 detects the crank angle. The cam angle sensor 18 detects the rotation angle of the intake camshaft 16. The air flow meter 19 detects the amount of intake air.

[0019] Vehicle 500 is equipped with various sensors. For example, vehicle 500 is equipped with a vehicle speed sensor 81, an accelerator sensor 82, and a current sensor 83. Vehicle speed sensor 81 detects the traveling speed of vehicle 500 as the vehicle speed. Accelerator sensor 82 detects the operation amount of an accelerator pedal in vehicle 500 as the accelerator operation amount. Current sensor 83 detects the magnitude of the current flowing through each of first MG 71 and second MG 72.

[0020] The vehicle 500 is equipped with a system activation switch (hereinafter referred to as the activation switch) 80. The activation switch 80 is also called a start switch or an ignition switch. The activation switch 80 is turned on or off in response to a user operation.

[0021] <Control device> The vehicle 500 is equipped with a control device 90. The control device 90 is equipped with a CPU 91 and a memory 92. The CPU 91 is an execution unit. The memory 92 includes three types of memory: a volatile memory, a ROM, and an electrically rewritable non-volatile memory 92A. In this embodiment, when these three types are described collectively, they are collectively referred to as the memory 92. The memory 92 is a storage unit. The memory 92 pre-stores various programs that describe the processes to be executed by the CPU 91, and various programs that are necessary for the CPU 91 to execute the programs. The non-volatile memory 92A is a memory that can retain its stored contents even when the start switch 80 is turned off and power supply to the non-volatile memory 92A is stopped.

[0022] The CPU 91 acquires an on / off signal from the start switch 80. While the start switch 80 is on, the CPU 91 repeatedly acquires detection signals from the various sensors mounted on the vehicle 500. The CPU 91 then calculates necessary parameters as needed based on the acquired information. For example, the CPU 91 calculates the rotational speed of the crankshaft 34 based on the detection signal from the crank angle sensor 36. For example, the CPU 91 calculates the actual opening and closing timing of the intake valve 15 based on the detection signal from the crank angle sensor 36 and the detection signal from the cam angle sensor 18. For example, the CPU 91 calculates the actual torque of each of the first MG 71 and the second MG 72 based on the detection signal from the current sensor 83. The CPU 91 controls various parts of the vehicle 500 based on the detection signals from the various sensors and the values ​​of the parameters obtained therefrom.

[0023] The CPU 91 controls various components of the vehicle 500. For example, the CPU 91 controls the engine 10, the first MG 71, and the second MG 72. Hereinafter, a target value of torque for the engine 10 will be referred to as a target engine torque. A target value of torque for the first MG 71 will be referred to as a first target torque. A target value of torque for the second MG 72 will be referred to as a second target torque. The CPU 91 repeatedly calculates a vehicle required torque, which is a torque required for the vehicle 500, while the start switch 80 is on. The CPU 91 calculates the vehicle required torque based on the latest vehicle speed and the latest accelerator operation amount. After calculating the vehicle required torque, the CPU 91 calculates a target engine torque, a first target torque, and a second target torque so as to satisfy the vehicle required torque. The CPU 91 repeatedly calculates these target values ​​while the start switch 80 is on. After calculating each target value, the CPU 91 controls the engine 10, the first MG 71, and the second MG 72 based on the calculated target value. That is, the CPU 91 controls the engine 10 so that the actual engine torque matches the latest target engine torque. The CPU 91 controls the first MG 71 so that the actual torque of the first MG 71 matches the latest first target torque. The CPU 91 controls the second MG 72 so that the actual torque of the second MG 72 matches the latest second target torque. When controlling the first MG 71 and the second MG 72, the CPU 91 essentially controls the PCU 200. While the start switch 80 is on, the CPU 91 repeatedly calculates each target value and controls each drive source based on the calculated target value. As described above, the CPU 91 calculates the vehicle required torque based on the vehicle speed and the accelerator operation amount. That is, the CPU 91 calculates the target engine torque, the first target torque, and the second target torque based on the traveling state of the vehicle 500 determined from the vehicle speed and the accelerator operation amount. Examples of methods for calculating these target values ​​are disclosed in Japanese Patent Application Laid-Open No. 2011-235694 and Patent Document 1, etc.

[0024] When calculating the target engine torque, the first target torque, and the second target torque, the CPU 91 sets each target value so that the first target torque is equal to or greater than the limit torque. The limit torque is a negative value that is predetermined in consideration of the power generation capacity of the first MG 71. That is, when the first target torque is a negative value, the absolute value of the first target torque is equal to or less than the absolute value of the limit torque. In this embodiment, a control mode in which the first MG 71 is controlled when the limit torque is set as the first target torque is referred to as limit control. That is, during execution of limit control, the CPU 91 controls the first MG 71 using the limit torque as the first target torque. At the same time, during execution of limit control, the CPU 91 controls the engine 10 with the target engine torque and the second MG 72 with the second target torque. For example, the CPU 91 switches an execution flag on or off depending on whether limit control is being executed. During execution of limit control, the CPU 91 turns on the execution flag. During non-execution of limit control, the CPU 91 turns off the execution flag. The limit torque is set to, for example, the rated torque of the first MG 71 or a value slightly smaller than the rated torque in absolute value. Examples of the limit torque are disclosed in Patent Document 1, etc.

[0025] As described in Patent Document 1 and elsewhere, a so-called nomographic diagram showing the relationship between the rotational speeds of the sun gear 41, carrier 44, and ring gear 42 of the planetary gear mechanism 40 shows that the rotational speeds of the sun gear 41, carrier 44, and ring gear 42 are aligned on a straight line. Due to this relationship, fluctuations in the rotation of the crankshaft 34 connected to the carrier 44 affect the rotation of the rotor of the first MG 71 connected to the sun gear 41. When a limit torque is set as the first target torque, if the actual engine torque deviates from the target engine torque, the actual torque of the first MG 71 may exceed the limit torque on the negative side, resulting in an overspeed state in which the first MG 71 generates excessive power. Therefore, in this embodiment, the specific control described below is executed to suppress the deviation of the actual engine torque from the target engine torque during execution of the limit control.

[0026] <Specific Control> The specific control is a control for controlling the VVT ​​mechanism 17 of the engine 10. In this embodiment, the opening / closing timing of the intake valve 15 is handled as follows. That is, within the variable range of the opening / closing timing of the intake valve 15 that can be achieved by the VVT ​​mechanism 17, the state in which the opening / closing timing is most retarded is set to an initial value of "0." The opening / closing timing of the intake valve 15 is expressed by the advance amount from this initial value. Hereinafter, this advance amount will be referred to as the index advance amount. When the crank angle corresponding to the initial value of the opening / closing timing of the intake valve 15 is defined as a base angle, the index advance amount is the amount of change in crank angle from the base angle to the advance side and takes a positive value. The memory 92 pre-stores the base angle for each cylinder 30. When actually controlling the VVT ​​mechanism 17, the CPU 91 determines the crank angle at which the intake valve 15 should actually be opened and closed based on the base angle and the index advance amount. When the opening and closing timing of the intake valve 15 is set to the initial value, the closing timing of the intake valve 15 is, for example, a timing that is retarded from the intake bottom dead center.

[0027] The CPU 91 starts the specific control when the start switch 80 is switched from off to on. The CPU 91 continues the specific control while the start switch 80 is on. The CPU 91 ends the specific control when the start switch 80 is switched from on to off. The CPU 91 repeatedly executes the processing routine described below while the specific control is continuing.

[0028] As shown in FIG. 4, when the CPU 91 starts the processing routine, it first executes the processing of step S10. In step S10, the CPU 91 determines whether limit control is being executed. For example, the CPU 91 makes the determination of step S10 based on the on / off state of an execution flag. If limit control is not being executed (step S10: NO), the CPU 91 proceeds to the processing of step S80. In this case, the CPU 91 controls the VVT ​​mechanism 17 normally. After executing the processing of step S80 for a predetermined control period, the CPU 91 temporarily ends the processing routine. Then, the CPU 91 executes the processing of step S10 again.

[0029] On the other hand, in step S10, if the limit control is being executed (step S10: YES), the CPU 91 proceeds to step S20. In step S20, the CPU 91 calculates the latest torque difference ΔT. The torque difference ΔT is a value obtained by subtracting the target engine torque from the actual engine torque. The actual engine torque can be calculated based on, for example, the gear ratio of the planetary gear mechanism 40 or the first target torque. The actual engine torque can also be calculated based on, for example, the transition in the rotational speed of the crankshaft 34. After calculating the torque difference ΔT, the CPU 91 proceeds to step S30.

[0030] In step S30, the CPU 91 calculates an update value N. The update value N is a value for updating the adjustment value H, which will be described later. As a prerequisite for the CPU 91 to calculate the update value N, the memory 92 stores an update map in advance. As shown in FIG. 3, the update map represents the correspondence relationship between the torque difference ΔT and the update value N. In the update map, a region where the torque difference ΔT is equal to or greater than "0" is referred to as a first region. In the first region, when the torque difference ΔT is less than a set value P, the update value N is "0." In the first region, when the torque difference ΔT is equal to or greater than the set value P, the update value N is a negative value. More specifically, in the first region, when the torque difference ΔT is equal to or greater than the set value P, the absolute value of the update value N increases as the torque difference ΔT increases. In the update map, a region where the torque difference ΔT is a negative value is referred to as a second region. In the second region, when the absolute value of the torque difference ΔT is less than the set value P, the update value N is "0." In the second region, when the absolute value of the torque difference ΔT is equal to or greater than the set value P, the update value N is a positive value. Specifically, in the second region, when the absolute value of the torque difference ΔT is equal to or greater than the set value P, the update value N increases as the absolute value of the torque difference ΔT increases. For both the first region and the second region, the update value N in the update map is determined in advance based on experiments or the like as an optimal value for adjusting the adjustment value H and, in turn, the opening and closing timing of the intake valve 15. In the update map, the slope of the line showing the correspondence relationship between the torque difference ΔT and the update value N may differ between the first region and the second region, or the correspondence may be nonlinear. The set value P is determined in advance based on experiments or the like as follows: That is, the set value P is the minimum absolute value of the torque difference ΔT at which it is considered that there is a steady deviation between the actual engine torque and the target engine torque.

[0031] In step S30, the CPU 91 refers to the update map and the latest torque difference ΔT calculated in step S20. Then, the CPU 91 calculates the update value N in the update map that corresponds to the latest torque difference ΔT as the update value N that applies to the current operating state of the engine 10. As shown in Fig. 4, once the CPU 91 calculates the current update value N, the process proceeds to step S40.

[0032] In step S40, the CPU 91 calculates the latest adjustment value H. The adjustment value H is a value for adjusting the opening / closing timing of the intake valve 15. When calculating the latest adjustment value H, the CPU 91 refers to the adjustment value HA calculated in the previous processing of step S40. The adjustment value HA calculated in the previous processing of step S40 is stored in the non-volatile memory 92A. The CPU 91 adds the current update value N calculated in step S30 to this adjustment value HA. The CPU 91 then treats the obtained value as the latest adjustment value H. The CPU 91 calculates the latest adjustment value H as a value that is less than or equal to a predetermined upper limit value and greater than or equal to a predetermined lower limit value. For example, if the value obtained by adding the update value N to the previous adjustment value HA is smaller than the lower limit value, the CPU 91 sets the lower limit value as the latest adjustment value H. The lower limit value is greater than "0." After calculating the latest adjustment value H, the CPU 91 stores this latest adjustment value H in the non-volatile memory 92A. At this time, the CPU 91 overwrites the previous adjustment value HA with the latest adjustment value H. Therefore, the nonvolatile memory 92A always holds the latest adjustment value H. When the vehicle 500 is shipped from the factory, the adjustment value H stored in the nonvolatile memory 92A is "1." After storing the latest adjustment value H in the nonvolatile memory 92A, the CPU 91 proceeds to step S50.

[0033] The following can be said about the processing of steps S30 and S40: The processing of steps S30 and S40 is a first processing for calculating the adjustment value H based on the torque difference ΔT. The processing of step S40 is a second processing for storing the latest adjustment value H of the adjustment values ​​H calculated in the first processing in the nonvolatile memory 92A.

[0034] In step S50, the CPU 91 calculates a base timing J1 for opening and closing the intake valve 15. The base timing J1 is a base value for the opening and closing timing of the intake valve 15 that corresponds to the current operating state of the engine 10, and is expressed using the index advance amount described above. The CPU 91 calculates the base timing J1 based on an index that indicates the operating state of the engine 10, such as the current rotation speed of the crankshaft 34 and the intake air amount. The memory 92 pre-stores information that indicates the correspondence between the index that indicates the operating state of the engine 10 and the base timing J1. The CPU 91 refers to this information when calculating the base timing J1. After calculating the base timing J1 that corresponds to the operating state of the engine 10, the CPU 91 proceeds to step S60.

[0035] In step S60, the CPU 91 calculates the adjustment timing J2 of the intake valve 15. The adjustment timing J2 is the opening / closing timing obtained by adjusting the base timing J1 by the adjustment value H. The CPU 91 refers to the base timing J1 calculated in step S50 and the latest adjustment value H stored in the non-volatile memory 92A in step S40. Then, the CPU 91 multiplies the base timing J1 by the latest adjustment value H. The CPU 91 handles the obtained value as the adjustment timing J2. After calculating the adjustment timing J2, the CPU 91 proceeds to step S70.

[0036] In step S70, the CPU 91 controls the VVT ​​mechanism 17 based on the adjustment timing J2 calculated in step S60. That is, the CPU 91 controls the VVT ​​mechanism 17 so that the actual opening / closing timing of the intake valve 15 coincides with the adjustment timing J2 calculated in step S60. The process of step S70 is the third process. After executing the process of step S70 for the above-mentioned predetermined control period, the CPU 91 temporarily ends the process routine. Then, the CPU 91 executes the process of step S10 again. Note that while the process of step S70 is being executed, the CPU 91 controls the devices in the engine 10 other than the VVT ​​mechanism 17 in the normal manner.

[0037] Here, the period from when the start switch 80 is switched on to when it is switched off, i.e., the period during which the control device 90 is operating, is referred to as one trip. Regarding the above processing routine, the adjustment value H across multiple trips is handled as follows. As described above, in the processing of step S40, the CPU 91 stores the most recent adjustment value H in the nonvolatile memory 92A. In relation to this, when a first trip ends, the nonvolatile memory 92A stores the final adjustment value, which is the adjustment value H last calculated by the CPU 91 for that first trip. Thereafter, the nonvolatile memory 92A retains this final adjustment value until the start of a second trip following the first trip. Then, in the processing of step S40 for the first time in the second trip, the CPU 91 calculates a new adjustment value H by treating the final adjustment value as the previously calculated adjustment value HA.

[0038] <About updating adjustment values ​​with updated values> As described above, the opening / closing timing in this embodiment is expressed as an advance amount of the opening / closing timing from the initial value. In consideration of this, adding a negative update value N to the adjustment value H, i.e., updating the adjustment value H to a smaller value, means retarding the adjustment value H and therefore the opening / closing timing. As shown in FIG. 3 , the update value N in the first region of the update map is negative when the torque difference ΔT is equal to or greater than the set value P. Regarding the first region having such characteristics, when the absolute value of the update value N in the first region is the first crank angle, the following can be said. That is, when the torque difference ΔT calculated in step S20 of the processing routine is positive and equal to or greater than the set value P, the negative update value N is added to the previously calculated adjustment value HA in step S40. This corresponds to retarding the previously calculated adjustment value HA by the first crank angle. The resulting new adjustment value H is a value obtained by retarding the previously calculated adjustment value HA by the first crank angle. In other words, the first crank angle constitutes a parameter that represents the correction width of the crank angle toward the retard side in relation to the adjustment value H. Note that the following can be said about the setting of the update value N for the first region in the update map. That is, in the first region of the update map, the first crank angle is determined in advance in correspondence with the torque difference ΔT. In the first region of the update map, when the torque difference ΔT is less than a set value P, the first crank angle is set to "0," and when the torque difference ΔT is equal to or greater than the set value P, the first crank angle increases as the torque difference ΔT increases.

[0039] Contrary to the retard correction described above, adding a positive update value N to the adjustment value H, i.e., updating the adjustment value H to a larger value, means advancing the adjustment value H and, therefore, the opening / closing timing. Here, as shown in FIG. 3, the update value N in the second region of the update map is a positive value when the absolute value of the torque difference ΔT is equal to or greater than the set value P. Regarding the second region having such characteristics, when the update value N in the second region is set to the second crank angle, the following can be said. That is, when the torque difference ΔT calculated in step S20 of the processing routine is negative and the absolute value of the torque difference ΔT is equal to or greater than the set value P, the positive update value N is added to the previously calculated adjustment value HA in step S40. This corresponds to performing an advance correction by the second crank angle on the previously calculated adjustment value HA. The resulting new adjustment value H is a value obtained by advancing the previously calculated adjustment value HA by the second crank angle. In other words, the second crank angle constitutes a parameter that represents the correction width of the crank angle toward the advance side in relation to the adjustment value H. Note that the following can be said about the setting of the update value N for the second region in the update map. That is, in the update map, the second crank angle is predetermined in association with the torque difference ΔT. In the second region of the update map, when the absolute value of the torque difference ΔT is less than a set value P, the second crank angle is set to "0," and when the absolute value of the torque difference ΔT is equal to or greater than the set value P, the second crank angle increases as the absolute value of the torque difference ΔT increases.

[0040] <Operation of the embodiment> Various factors can cause the actual engine torque to deviate from the target engine torque. One example of these factors is a difference in ignition timing due to differences in fuel properties, such as octane number or alcohol content. Another example of these factors is a difference in the amount of friction of the piston 33 due to individual differences in the engine 10. These factors can cause the actual engine torque to steadily deviate from the target engine torque. As described below, specific control can eliminate the torque difference ΔT caused by these factors, for example, and operate the engine 10. Although a detailed description will be omitted, the update of the adjustment value H and the control of the VVT ​​mechanism 17 using the adjustment value H, which will be described below, are performed during execution of limit control.

[0041] If a torque difference ΔT exists at a certain timing, the torque difference ΔT is eliminated as follows. Now, assume that the torque difference ΔT is positive and equal to or greater than a set value P. In this case, the CPU 91 retards the adjustment value H. The CPU 91 then calculates the adjustment timing J2 using this adjustment value H. When the CPU 91 controls the VVT ​​mechanism 17 based on this adjustment timing J2, the actual engine torque becomes smaller than before the adjustment value H was retarded. As a result, the absolute value of the torque difference ΔT becomes smaller. On the other hand, when the torque difference ΔT is negative and the absolute value of the torque difference ΔT is equal to or greater than the set value P, the CPU 91 advances the adjustment value H. When the CPU 91 controls the VVT ​​mechanism 17 based on the adjustment timing J2 corresponding to this adjustment value H, the actual engine torque becomes larger than before the adjustment value H was advanced. As a result, the absolute value of the torque difference ΔT becomes smaller. Based on this causal relationship, if the adjustment value H continues to be updated in accordance with the magnitude of the torque difference ΔT, the absolute value of the torque difference ΔT gradually decreases. The absolute value of the torque difference ΔT eventually becomes less than the set value P. At the same time, the adjustment value H converges to a value that is effective in eliminating the torque difference ΔT. Note that as the adjustment value H converges, the adjustment value H changes in increments of a predetermined first crank angle or a predetermined second crank angle. Therefore, the adjustment value H does not overshoot or undershoot as it converges.

[0042] The above-described changes in the adjustment value H and torque difference ΔT will be explained in relation to each trip of the vehicle 500. Examples of factors that cause a steady torque difference ΔT, such as fuel properties or the magnitude of friction of the piston 33, do not generally change within a single trip. Therefore, even if a relatively large torque difference ΔT exists, for example, in the initial stage of a first trip, once the torque difference ΔT is eliminated during that first trip—that is, once the adjustment value H converges to a value effective in eliminating the torque difference ΔT—the absolute value of the torque difference ΔT will remain small each time limit control is executed during that first trip. In other words, once the adjustment value H converges to an appropriate value, the VVT ​​mechanism 17 can be consistently controlled using that optimal adjustment value H from the start of each limit control thereafter. Furthermore, in this embodiment, the nonvolatile memory 92A continues to store the adjustment value H after the first trip ends until the subsequent second trip begins. Therefore, the adjustment value H that was effective in eliminating the torque difference ΔT in the first trip is carried over to the second trip. Factors that cause the torque difference ΔT, such as fuel properties or the magnitude of friction of the piston 33, generally remain substantially unchanged across trips. In other words, the adjustment value H that was effective in eliminating the torque difference ΔT in the first trip remains effective in eliminating the torque difference ΔT in the second trip. Therefore, during the second trip, the CPU 91 can control the VVT ​​mechanism 17 using the optimal adjustment value H during each execution of limit control from the start of the second trip. This allows the CPU 91 to operate the engine 10 with substantially no torque difference ΔT during each execution of limit control from the start of the second trip. The same applies to subsequent trips, from the third trip onward.

[0043] <Effects of the embodiment> (1) If VVT mechanism 17 is controlled using feedback control during limit control, the actual value may overshoot or undershoot the target value, and the actual value may fluctuate relative to the target value each time limit control is executed. In this regard, with the configuration of this embodiment, if a torque difference ΔT exists during a trip, adjustment value H can be converged to an optimal value that eliminates the torque difference ΔT without overshooting or undershooting. Once adjustment value H has converged to the optimal value, VVT mechanism 17 can be controlled using the optimal adjustment value H during each execution of limit control. Furthermore, during that trip, engine 10 can be operated with almost no torque difference ΔT. Therefore, with the configuration of this embodiment, overspeeding of first MG 71 can be suppressed during that trip.

[0044] (2) Furthermore, in the configuration of this embodiment, the optimal adjustment value H that can eliminate the torque difference ΔT is maintained across multiple trips, so that the engine 10 can be operated in a state where the torque difference ΔT is substantially eliminated during each execution of limit control in each trip. Therefore, the occurrence of overspeed in the first MG 71 can be suppressed in each trip.

[0045] (3) The larger the torque difference ΔT, the larger the correction range of the adjustment value H required to eliminate the torque difference ΔT. As in this embodiment, by variably setting the first crank angle, which is the correction range of the adjustment value H toward the retard side, in accordance with the torque difference ΔT, it is possible to optimize the correction range of the adjustment value H when updating the adjustment value H to eliminate a positive torque difference ΔT. Furthermore, when the torque difference ΔT is large, the adjustment value H can be quickly updated to a value required to eliminate the torque difference ΔT.

[0046] (4) As in (3), by variably setting the second crank angle, which is the correction width of the adjustment value H to the advance side, in accordance with the torque difference ΔT, as in this embodiment, it is possible to optimize the correction width of the adjustment value H when updating the adjustment value H to eliminate the negative torque difference ΔT. Furthermore, when the absolute value of the torque difference ΔT is large, it is possible to quickly update the adjustment value H to a value necessary to eliminate the torque difference ΔT.

[0047] (5) Due to minute fluctuations in the actual engine torque, the torque difference ΔT may fluctuate around zero. If the adjustment value H is updated in accordance with these minute fluctuations in the engine torque, the opening and closing timing of the intake valve 15 would be repeatedly adjusted back and forth, which could place a burden on the VVT ​​mechanism 17 and other components. The configuration of this embodiment can suppress overspeed in the first MG 71 without imposing such a burden.

[0048] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0049] With regard to the processing of step S40, the CPU 91 may store the latest adjustment value H in volatile memory instead of storing the latest adjustment value H in nonvolatile memory 92A. Then, when the startup switch 80 is switched from on to off, the CPU 91 may perform processing to store the latest adjustment value H stored in volatile memory in nonvolatile memory 92A. Note that when the mode of storing the adjustment value H in volatile memory is adopted in the processing of step S40, it is not essential to perform processing to store the adjustment value H in nonvolatile memory 92A when the startup switch 80 is switched off. And if the adjustment value H is not stored in nonvolatile memory 92A, the nonvolatile memory 92A may be eliminated.

[0050] The correspondence relationship between the torque difference ΔT and the first crank angle in the update map is not limited to the example in the above embodiment. This correspondence relationship may be determined as long as it is appropriate from the perspective of adjusting the adjustment value H. For example, the first crank angle may be set to a value other than "0" when the torque difference ΔT is less than a set value. It is preferable for updating the adjustment value H to eliminate a positive torque difference ΔT if the first crank angle in the update map satisfies the following first condition. The first condition is that when the torque difference ΔT is a positive first value, the first crank angle is set to a value larger than when the torque difference ΔT is a positive second value smaller than the first value. However, it is not essential that the first crank angle in the update map satisfy the first condition. For example, the first crank angle in the update map may be set to a constant value regardless of the torque difference ΔT.

[0051] As in the above modified example, the correspondence relationship between the torque difference ΔT and the second crank angle in the update map is not limited to that in the above embodiment. For example, the second crank angle may be set to a value other than "0" when the absolute value of the torque difference ΔT is less than a set value. Note that if the second crank angle in the update map is determined to satisfy the following second condition, it is preferable for updating the adjustment value H to eliminate the negative torque difference ΔT. The second condition is that when the torque difference ΔT is a negative third value, the second crank angle is determined to be a larger value than when the torque difference ΔT is a negative fourth value greater than the third value. However, it is not essential that the second crank angle in the update map satisfy the second condition.

[0052] The adjustment value H is not limited to adjusting the base timing J1 by multiplication. For example, the adjustment value H may adjust the base timing J1 by addition. The adjustment value H, and therefore the first crank angle and the second crank angle, may be set appropriately depending on how the base timing J1 is adjusted. Furthermore, the adjustment value H may be calculated based on the difference between the actual engine torque and the target engine torque, and does not necessarily have to be calculated based on the value obtained by subtracting the target engine torque from the actual engine torque.

[0053] The overall configuration of the vehicle is not limited to the example of the above embodiment. The vehicle may include an engine with a variable valve timing mechanism, a generator capable of generating electricity using engine power, a planetary gear mechanism that distributes power among the engine, the generator, and the drive wheels, and an electric motor that powers the drive wheels. [Explanation of symbols]

[0054] 10... engine 17... VVT mechanism 40... planetary gear mechanism 71... first MG 72... second MG 90... control device 91... CPU 92A... non-volatile memory 500... vehicle

Claims

1. The control target is a vehicle that includes an engine having a variable valve timing mechanism that adjusts the opening and closing timing of an intake valve, a generator that can generate electricity using the power of the engine, a planetary gear mechanism that distributes power among the engine, the generator, and drive wheels, and an electric motor that provides power to the drive wheels, a limit control that controls the engine with a target engine torque calculated based on a running state of the vehicle and controls the generator with a predetermined limit torque as a target torque; During execution of the limit control, a first process of calculating an adjustment value for adjusting the opening / closing timing based on a difference between an actual engine torque and the target engine torque; a second process of storing the latest adjustment value among the adjustment values ​​calculated in the first process; a third process for controlling the variable valve timing mechanism so that the actual opening / closing timing coincides with an adjusted timing obtained by adjusting a base timing according to an operating state of the engine using the latest adjustment value stored in the second process; and Repeatedly execute In the first process, when the actual engine torque is greater than the target engine torque, a value obtained by retarding the previously calculated adjustment value by a predetermined first crank angle is calculated as a new adjustment value, and when the actual engine torque is less than the target engine torque, a value obtained by advancing the previously calculated adjustment value by a predetermined second crank angle is calculated as a new adjustment value. Vehicle control device.

2. When the period from when the start switch of the vehicle is turned on to when it is turned off is defined as one trip, a nonvolatile memory that stores the adjustment value calculated last in a first trip and holds the adjustment value from the end of the first trip until the start of a subsequent second trip; In the first process of the second trip, the adjustment value calculated last in the first trip is treated as the adjustment value calculated previously, and a new adjustment value is calculated. The vehicle control device according to claim 1 .

3. when a value obtained by subtracting the target engine torque from the actual engine torque is defined as a torque difference, the first crank angle is determined in advance in correspondence with the torque difference, When the torque difference is a positive first value, the first crank angle is set to a value larger than when the torque difference is a positive second value smaller than the first value. The vehicle control device according to claim 1 .

4. when a value obtained by subtracting the target engine torque from the actual engine torque is defined as a torque difference, the second crank angle is determined in advance in correspondence with the torque difference, When the torque difference is a negative third value, the second crank angle is set to a value larger than when the torque difference is a negative fourth value larger than the third value. The vehicle control device according to claim 1 .

5. When a value obtained by subtracting the target engine torque from the actual engine torque is defined as a torque difference, if the absolute value of the torque difference is less than a predetermined set value, the first crank angle and the second crank angle are set to zero. The vehicle control device according to claim 1 .

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