Vehicle drive force control device

Abstract

To improve a deviation between an actual torque and a target torque while suppressing a response lag of a torque change to an accelerator operation by a driver.SOLUTION: A drive force control device of a vehicle includes a motor 5, an engine 4 and a controller 20. The controller distributes a target engine torque from a target torque of a vehicle according to a prescribed distribution rule and outputs a control signal corresponding to the target engine torque to the engine. The controller predicts an intake air quantity to a cylinder in the future later than the present time on the basis of the target engine torque, and predicts the torque of the engine after a set time later than the present time on the basis of the predicted intake air quantity. Tthe controller sets the target motor torque after the set time so that the target torque of the vehicle is achieved on the basis of the predicted torque of the engine after the set time, outputs the control signal corresponding to the target motor torque to the motor, and synchronizes the torque response of the engine with the torque response of the motor.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The technology disclosed herein relates to a driving force control device for a vehicle.

Background Art

[0002] Patent Document 1 discloses a hybrid vehicle equipped with an engine and a motor. The engine and the motor share and output a required torque according to the accelerator operation of the driver. When the controller of this hybrid vehicle requests an increase in torque for both the engine and the motor, it delays the torque request for the motor for a predetermined time simulating the response delay of the engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A hybrid vehicle equipped with an engine and a motor distributes the target torque of the vehicle to the engine and the motor so that the energy efficiency is optimized. The torque distribution to the engine and the motor changes sequentially according to various engine states including, for example, the battery state such as SOC (State of Charge), and / or temperature, and / or the engine coolant temperature.

[0005] Generally, the torque response of the engine is slower than that of the motor. Therefore, during a transient when the target torque changes, the torque change of the engine may lag behind the torque change of the motor. The lag in the torque change of the engine causes torque fluctuations in the vehicle. Also, the lag in the torque change of the engine may cause a deviation between the total torque actually generated by the engine and the motor and the target torque.

[0006] Conventional hybrid vehicles delay the timing of the motor's torque increase to match the timing of the engine's torque increase. Because the torque increases of the engine and the motor are synchronized in conventional hybrid vehicles, torque fluctuations are less likely to occur.

[0007] However, in conventional hybrid vehicles, the timing of the motor's torque increase is delayed, resulting in a delay in the vehicle's torque increase in response to the driver's accelerator input. Conventional hybrid vehicles have poor drivability. Furthermore, unfortunately, conventional hybrid vehicles only synchronize the torque increase of the engine and the motor, so they cannot improve the discrepancy between actual torque and target torque.

[0008] The technology disclosed herein improves the discrepancy between actual torque and target torque while suppressing the response delay of torque changes to the driver's accelerator input. [Means for solving the problem]

[0009] In hybrid vehicles equipped with both an engine and a motor, it is conceivable that the motor can compensate for the engine's response delay, thereby achieving both suppression of the response delay and improvement of the torque discrepancy. Specifically, when changing the target engine torque in response to the driver's accelerator operation, the controller can calculate the difference between the actual engine torque and the target engine torque, and then correct the target motor torque so that the difference in engine torque is compensated for by the motor torque. A highly responsive motor can compensate for the difference in engine torque caused by the engine's response delay. Compensation by the motor can suppress the delay in torque response to accelerator operation and also improve the discrepancy between the actual torque and the target torque.

[0010] However, detecting engine torque, calculating the torque difference, and / or setting the motor torque correction amount takes time. In the control process described above, the actual engine torque changes constantly even while the engine torque is being detected and the motor correction amount is being set. Motor torque correction lags behind changes in actual engine torque. The discrepancy between actual torque and target torque will not disappear.

[0011] The inventors of this invention conceived a technological concept that predicts engine torque in the future by anticipating changes in engine torque, and sets a target motor torque at a set time from the present based on the predicted engine torque. The inventors of this invention proceeded to develop a control system that realizes this technological concept, and have completed the technology disclosed herein.

[0012] Specifically, the technology disclosed herein relates to a vehicle drive force control device. This vehicle drive force control device is A motor that receives power and generates torque for vehicle propulsion, An engine that generates torque for vehicle propulsion by burning fuel in a cylinder, The system includes a controller that receives an accelerator operation signal and outputs a control signal corresponding to the accelerator operation to the motor and the engine, The controller sets a target torque for the vehicle corresponding to the accelerator operation, distributes the target engine torque from the vehicle's target torque according to a predetermined distribution rule, and outputs a control signal to the engine corresponding to the target engine torque. The controller predicts the amount of intake air to the cylinder in the future based on the target engine torque, and predicts the engine torque at a set time from the present based on the predicted amount of intake air. The controller sets a target motor torque after a set time based on the predicted engine torque after the set time so that the target torque of the vehicle is achieved, and outputs a control signal to the motor corresponding to the target motor torque. This eliminates the discrepancy between the actual torque and the target torque.The torque response of the engine and the torque response of the motor are synchronized.

[0013] This configuration of vehicle is a so-called hybrid vehicle, equipped with both a motor and an engine. The controller distributes the vehicle's target torque to a target engine torque and a target motor torque so that the vehicle's target torque corresponding to accelerator input is achieved. The engine outputs the target engine torque, and the motor outputs the target motor torque. The engine and motor work together to achieve the vehicle's target torque.

[0014] The controller distributes the target engine torque according to a predetermined distribution rule. The distribution rule is, for example, based on the battery's State of Charge (SOC). The battery is installed in the vehicle to supply power to the motor. If the SOC is high, the controller may prioritize battery discharge by setting a low target engine torque and a high target motor torque. If the SOC is low, the controller may prioritize battery charging by setting a high target engine torque and a low target motor torque. The controller outputs a control signal to the engine corresponding to the target engine torque. The engine operates to output the target engine torque.

[0015] When the driver operates the accelerator, the controller changes the vehicle's target torque to correspond to the change in accelerator operation. Along with the change in the vehicle's target torque, the controller changes the target engine torque. When the target engine torque changes, the engine, for example, changes the throttle valve opening, which in turn changes the amount of intake air into the cylinders. A change in the amount of intake air into the cylinders changes the engine torque. There is a time lag between the change in target torque, the change in throttle valve opening and intake air volume, and the actual change in engine torque.

[0016] The change in throttle valve opening in response to a change in target engine torque can be predicted by pre-determining the throttle valve's characteristics (including mechanical characteristics). If the change in throttle valve opening in the future can be predicted, the amount of intake air in the future can be predicted, and if the amount of intake air can be predicted, the engine torque in the future can be predicted. The controller predicts the engine torque in the future based on the target engine torque. More precisely, the controller predicts the engine torque from the present to a set time interval.

[0017] The controller also predicts the engine torque at a set time from the current moment and sets a target motor torque at that time so that the vehicle's target torque is achieved. If the predicted engine torque is lower than the target engine torque, the target motor torque is set high to compensate for the engine torque deficit. If the predicted engine torque is higher than the target engine torque, the target motor torque is set low to account for the engine torque surplus. The set target motor torque compensates for any delay in the engine's torque response.

[0018] The controller outputs a control signal to the motor corresponding to the target motor torque. Because the motor's torque response is generally fast, the motor can output torque corresponding to the target motor torque after a set time. The engine's torque response and the motor's torque response are synchronized. As a result, torque fluctuations in the vehicle are suppressed, and the vehicle's target torque is achieved.

[0019] Because the highly responsive motor compensates for the engine's response delay, the aforementioned drive force control device suppresses the response delay of torque changes in response to accelerator operation.

[0020] Further, instead of the actual engine torque, the engine torque in the future is predicted, and based on the predicted engine torque in the future, the target motor torque is set. The set target motor torque does not follow the change in the actual engine torque. In the above-described driving force control device, by synchronizing the torque response of the engine and the torque response of the motor, the deviation between the actual torque and the target torque can be eliminated or substantially eliminated.

[0021] As a result, the above-described driving force control device of the vehicle improves the drivability of the driver.

[0022] When predicting the torque of the engine, the controller delays the torque change of the engine with respect to the change in the predicted intake air amount more when the engine speed is low than when it is high. ru.

[0023] When the engine speed is high, the combustion interval (i.e., time interval) for a plurality of cylinders of the engine is short. When the engine speed is low, the combustion interval (i.e., time interval) for a plurality of cylinders is long. The time from when the intake air amount to the cylinder changes until the engine torque actually changes varies according to the engine speed. When the engine speed is high, the time from when the intake air amount to the cylinder changes until the engine torque changes is short. When the engine speed is low, the time from when the intake air amount to the cylinder changes until the engine torque changes is long.

[0024] The controller delays the change in engine torque in response to predicted changes in intake air volume when the engine speed is low, compared to when the engine speed is high. The controller can accurately predict changes in engine torque in the future rather than the present time. By setting the target motor torque based on the engine torque after a set time that has been predicted with high accuracy, the torque responses of the engine and motor are synchronized, and the vehicle torque accurately matches the target torque. The drive force control device can eliminate, or substantially eliminate, the discrepancy between the actual torque and the target torque while suppressing the response delay of torque changes to accelerator operation.

[0025] The controller may shorten the delay time related to torque changes as the engine speed increases, and may also set the delay time to zero when the engine speed is higher than the reference speed.

[0026] The higher the engine speed, the shorter the delay between a change in the amount of intake air into a cylinder and a change in engine torque. Reducing the delay time related to torque changes at higher engine speeds improves the accuracy of predicting engine torque in the future.

[0027] When the engine speed is sufficiently high, the delay time related to torque changes becomes extremely short, reducing the need to set a delay time. Even if the delay time is set to zero when the engine speed is higher than the reference speed, the controller can accurately predict the engine torque.

[0028] Furthermore, as engine speed increases, the responsiveness of the engine to torque changes improves, resulting in the engine's torque responsiveness becoming equivalent to, or even higher than, the motor's torque responsiveness. When the engine speed is high, it might be considered to speed up the motor's torque response in order to synchronize it with the engine's torque response. However, because the time required for one rotation of both the engine and the motor is short, the engine's torque response and the motor's torque response are substantially synchronized even without speeding up the motor's torque response.

[0029] The controller may set the target motor torque to compensate for the difference between the predicted engine torque and the target engine torque.

[0030] The motor can compensate for the engine's response delay.

[0031] The controller may predict the torque of the engine from the present time to a set time later, based on the predicted intake air volume and the optimal ignition timing determined from the operating state of the engine.

[0032] Here, the optimal ignition timing may be defined as, for example, MBT (Minimum advance for the Best Torque). If the controller sets the target engine torque based on MBT, the engine will operate at its best efficiency. The motor can then assist the engine, which is operating at its best efficiency.

[0033] Furthermore, for example, if the engine's catalytic converter is inactive and the engine is operating in AWS (Accelerated Warm-up System) mode, the optimal ignition timing is retarded compared to MBT (Mechanical Burst Timing). The optimal ignition timing is not necessarily MBT. In this case, the engine can attempt to activate the catalytic converter earlier. While the catalytic converter is being activated earlier, the motor can assist the engine.

[0034] The controller sets the target motor torque to be equal to or greater than the minimum torque that the motor can generate. The controller may, when the target motor torque is limited by the minimum torque, retard the ignition timing of the engine compared to the optimal ignition timing so that the engine torque decreases.

[0035] Generally, the minimum torque a motor can generate is determined by the temperature. Furthermore, if the battery's State of Charge (SOC) is high, the motor cannot perform regenerative braking, thus lowering the minimum torque. The motor's performance also determines the minimum torque it can generate. The controller must set the target motor torque to be greater than or equal to the minimum torque the motor can generate. If the target motor torque is limited by the minimum torque, the set target motor torque will be relatively large. This could lead to the combined torque of the motor and engine, i.e., the actual torque of the vehicle, exceeding the target torque.

[0036] If the target motor torque is limited by the minimum torque, the controller retards the engine's ignition timing beyond the optimal timing. Retarding the ignition timing reduces the engine torque, thus preventing the vehicle's torque from exceeding the target torque.

[0037] The aforementioned controller, Based on the aforementioned target engine torque, the change in the opening degree of the engine's throttle valve after accelerator operation is predicted. The amount of air passing through the throttle valve is predicted from the predicted throttle valve opening and the pressure in the engine's intake manifold. From the predicted amount of air passing through the throttle valve, the amount of air in the intake manifold is predicted. Alternatively, the amount of intake air to the cylinder may be predicted from the predicted amount of air in the intake manifold.

[0038] The change in throttle valve opening after accelerator operation can be predicted, for example, by pre-determining the mechanical characteristics of the throttle valve. If the throttle opening in the future can be predicted, the amount of air passing through the throttle valve in the future can be predicted from the pressure in the intake manifold downstream of the throttle valve and the intake pressure upstream of the throttle valve, for example using Bernoulli's equation. Note that the pressure in the intake manifold may be the amount of air in the intake manifold converted to pressure, as described later. Alternatively, for example, a pressure sensor may measure the intake pressure upstream of the throttle valve.

[0039] If the amount of air passing through the throttle valve can be predicted, the amount of air in the intake manifold can be predicted, and if the amount of air in the intake manifold can be predicted, the amount of intake air to the cylinders can be predicted. The controller can predict the amount of intake air to the cylinders in the future rather than the present moment.

[0040] The aforementioned controller, Based on the aforementioned target engine torque, the change in the opening and closing timing of the engine's intake valve after accelerator operation is predicted. From the predicted opening and closing timing of the intake valve, the filling efficiency is predicted. The amount of intake air to the cylinder may be predicted based on the predicted filling efficiency and the predicted amount of air in the intake manifold.

[0041] The change in the opening and closing timing of the intake valve after accelerator operation can be predicted by pre-determining the characteristics (including mechanical characteristics, for example) of the valve train mechanism that changes the opening and closing timing of the intake valve. Furthermore, by pre-determining the relationship between the opening and closing timing of the intake valve, the engine's operating state, and the volumetric efficiency for the engine in question, the controller can predict the volumetric efficiency based on the predicted opening and closing timing.

[0042] If the charging efficiency can be predicted, the amount of intake air to each cylinder can be predicted with greater accuracy based on the amount of air in the intake manifold and the charging efficiency. The controller can then predict the amount of intake air to each cylinder in the future with greater precision than it does now. [Effects of the Invention]

[0043] The aforementioned vehicle drive force control device can improve the discrepancy between actual torque and target torque while suppressing the response delay of torque changes to the driver's accelerator input. [Brief explanation of the drawing]

[0044] [Figure 1] Figure 1 shows a hybrid vehicle. [Figure 2] Figure 2 is a block diagram of the drive force control device. [Figure 3] Figure 3 shows a map relating to the modes of hybrid vehicles. [Figure 4] Figure 4 shows the functional blocks of the controller. [Figure 5] Figure 5 shows the functional block of the torque distribution unit. [Figure 6] Figure 6 shows the functional block of the engine control unit. [Figure 7] Figure 7 shows the relationship between engine speed and delay time. [Figure 8] Figure 8 shows the timing chart for drive force control. [Figure 9] Figure 9 shows a modified example of the torque distribution section. [Figure 10] Figure 10 is a flowchart related to the control of the drive force control device. [Modes for carrying out the invention]

[0045] The following describes an embodiment of a vehicle's drive force control device with reference to the drawings. The drive force control device described here is an example.

[0046] (Hybrid vehicles) Figure 1 shows an automobile 1 (an example of a vehicle) to which the disclosed technology is applied. This automobile 1 is a hybrid vehicle capable of running on electricity. Automobile 1 has a total of four wheels: two front wheels 2F and two rear wheels 2R.

[0047] Automobile 1 is equipped with an engine 4 and a motor 5 as its power sources. These work together to drive the rear wheels 2R, thereby enabling automobile 1 to move. Automobile 1 is a rear-wheel-drive vehicle. In addition to being a power source, motor 5 is also used as a generator during regenerative braking.

[0048] This vehicle 1 is equipped with a high-voltage battery 9. Power supplied from the high-voltage battery 9 allows the motor 5 to generate torque for driving the vehicle 1. An external power source 31 is connected to the high-voltage battery 9 via a power supply port 3. The high-voltage battery 9 is charged by the external power source 31. Vehicle 1 is a so-called plug-in hybrid vehicle. Note that vehicle 1 may also be a hybrid vehicle without the power supply port 3.

[0049] In this automobile 1, the engine 4 is located at the front of the vehicle, and the drive wheels are located at the rear of the vehicle. In other words, this automobile 1 is a so-called FR (front-engine, rear-wheel drive) vehicle.

[0050] Automobile 1 is equipped with an engine 4, a motor 5, and as part of its drivetrain, a K0 clutch 6, an inverter 7, and an automatic transmission 8. Automobile 1 is also equipped with a controller 20 as part of its control system.

[0051] (Drive system components) Engine 4 is, for example, an internal combustion engine that burns fossil fuels. Engine 4 is also a so-called four-stroke engine that generates rotational power by repeating the intake, compression, expansion, and exhaust cycles.

[0052] Engine 4 is a spark-ignition engine. However, Engine 4 may also be a compression-ignition engine. Engine 4 has multiple cylinders. However, the number of cylinders in Engine 4 is not limited to a specific number.

[0053] In this automobile 1, the engine 4 is positioned approximately in the center of the vehicle's width direction, with the crankshaft 4a, which outputs rotational power, facing in the front-to-rear direction of the vehicle body. The automobile 1 is equipped with various devices and mechanisms associated with the engine 4, such as an intake system, exhaust system, fuel supply system, and ignition system. The engine 4 will be described later.

[0054] Motor 5 is a permanent magnet type synchronous motor driven by three-phase alternating current. Motor 5 is located in series behind the engine 4 via the K0 clutch 6. Motor 5 is also located in series in front of the automatic transmission 8.

[0055] The K0 clutch 6 is installed between the front end of the shaft 5a of the motor 5 and the crankshaft 4a of the engine 4. The K0 clutch 6 switches between a state in which the crankshaft 4a and shaft 5a are connected (connected state) and a state in which the crankshaft 4a and shaft 5a are separated (separated state).

[0056] The rear end of the motor 5's shaft 5a is connected to the input shaft 8a of the automatic transmission 8. Therefore, the engine 4 is connected to the automatic transmission 8 via the K0 clutch 6 and shaft 5a. By disengaging the K0 clutch 6, the engine 4 is disconnected from the automatic transmission 8.

[0057] While the vehicle 1 is in motion, the K0 clutch 6 is switched between an engaged state and an engaged state. For example, when the vehicle 1 is decelerating, the K0 clutch 6 may be put into the engaged state, and regeneration may be performed with the engine 4 disconnected.

[0058] The motor 5 is connected to a vehicle-mounted high-voltage battery 9, which serves as the drive power source, via an inverter 7 and a high-voltage cable 40. A contactor 90 is interposed in the high-voltage cable 40.

[0059] The high-voltage battery 9 supplies high-voltage DC power to the inverter 7. The inverter 7 converts this DC power into three-phase AC power and energizes the motor 5. This causes the motor 5 to rotate. The motor 5 also supplies regenerative energy back to the high-voltage battery 9.

[0060] The high-voltage battery 9 is also connected to the DC-DC converter 10 via a high-voltage cable 40. The DC-DC converter 10 converts high-voltage DC power to low-voltage DC power of 12V and outputs it. The DC-DC converter 10 (its output side) is connected to the low-voltage battery 11 (a so-called lead-acid battery) via a low-voltage cable 45.

[0061] The low-voltage battery 11 is connected to various electrical components via low-voltage cables 45. The DC-DC converter 10 is also connected to the CAN (Controller Area Network) 12 via low-voltage cables 45. As a result, the DC-DC converter 10 supplies low-voltage DC power to the CAN 12.

[0062] The automatic transmission 8 is a multi-stage automatic transmission (so-called AT). The automatic transmission 8 has an input shaft 8a at its front end, and this input shaft 8a is connected to the shaft 5a of the motor 5 as described above. The automatic transmission 8 has an output shaft 8b at its rear end, which rotates independently of the input shaft 8a.

[0063] A gear shift mechanism consisting of multiple planetary gears and multiple friction fastening elements is incorporated between the input shaft 8a and the output shaft 8b. Each friction fastening element is switched between a fastened and disfastened state by hydraulic pressure. The automatic transmission 8 selectively fastens the multiple friction fastening elements by hydraulic control. The gears of the automatic transmission 8 switch between forward gears from 1st to 8th gear and reverse gears (reverse speed).

[0064] Furthermore, if the elements that should be fastened in each gear are not fastened, the connection between the input shaft 8a and the output shaft 8b will be disconnected (so-called neutral). Even if rotational power is input to the automatic transmission 8 from the drive source, that rotational power will not be output from the automatic transmission 8.

[0065] As shown in Figure 1, the output shaft 8b of the automatic transmission 8 is connected to the differential gear 16 via a propeller shaft 15 that extends in the longitudinal direction of the vehicle body. The differential gear 16 is connected to a pair of drive shafts 17, 17 that extend in the width direction of the vehicle and are connected to the left and right rear wheels 2R, 2R. The rotational power output through the propeller shaft 15 is distributed by the differential gear 16 and then transmitted to each rear wheel 2R through this pair of drive shafts 17, 17.

[0066] (engine) As shown in Figure 2, engine 4 includes a spark plug 41, an injector 42, a throttle valve 43, and an intake S-VT (Sequential-Valve Timing) 44.

[0067] The spark plug 41 is installed in the engine 4. The spark plug 41 receives a control signal from the controller 20 and forcibly ignites the fuel-air mixture in the cylinder.

[0068] The injector 42 is mounted on the engine 4. The injector 42 receives a control signal from the controller 20 and injects fuel, for example, into the cylinder. The fuel and the air drawn into the cylinder form a fuel-air mixture.

[0069] The throttle valve 43 is a butterfly valve installed in the intake passage of the engine 4. The throttle valve 43 changes its opening degree in response to a control signal from the controller 20. When the opening degree of the throttle valve 43 changes, the amount of air drawn into the cylinder changes. When the opening degree of the throttle valve 43 increases, the amount of intake air increases. When the opening degree of the throttle valve 43 decreases, the amount of intake air decreases.

[0070] The intake S-VT44 changes the opening and closing timing of the intake valve, for example, continuously. The intake S-VT44 is hydraulically driven or electrically driven. The intake S-VT44 receives a control signal from the controller 20 and changes the opening and closing timing of the intake valve in the advance or retard direction. When the intake S-VT44 changes the opening and closing timing of the intake valve, the volumetric efficiency changes. The change in the opening degree of the throttle valve 43 and the change in the opening and closing timing of the intake valve combine to change the amount of intake air into the cylinder.

[0071] (Drive force control device) Figure 2 is a block diagram of the drive force control device. The automobile 1 is equipped with the controller 20 described above to control the movement of the automobile 1 by controlling the engine 4, motor 5, K0 clutch 6, automatic transmission 8, etc., in response to the driver's operation. The controller 20 consists of hardware such as a processor, memory, and interface, and software such as a database and control program. Although Figure 2 shows a single controller 20 for the drive force control device, the controller of the drive force control device may be divided into a unit (PCM) that mainly controls the operation of the drive source (engine 4 and motor 5) and a unit (TCM) that mainly controls the operation of the K0 clutch 6 and automatic transmission 8. The PCM and TCM are connected by CAN 12 and configured to communicate with each other electrically.

[0072] The drive force control device is equipped with sensors that measure various parameters related to the vehicle's operation. Specifically, the drive force control device includes an accelerator position sensor 51, an intake pressure sensor 52, a water temperature sensor 53, an engine speed sensor 54, a motor speed sensor 55, a vehicle speed sensor 56, and a SOC sensor 57.

[0073] The accelerator position sensor 51 outputs a signal corresponding to the operation of the accelerator pedal 19 (see Figure 1) operated by the driver.

[0074] The intake pressure sensor 52 outputs a signal corresponding to the pressure in the intake passage of the engine 4 upstream of the throttle valve 43. The water temperature sensor 53 outputs a signal corresponding to the temperature of the coolant in the engine 4.

[0075] The engine speed sensor 54 outputs a signal corresponding to the rotational speed of engine 4. The motor speed sensor 55 outputs a signal corresponding to the rotational speed of motor 5. In automobile 1, when the K0 clutch 6 is engaged and both engine 4 and motor 5 are outputting torque, the rotational speed of engine 4 and the rotational speed of motor 5 will be the same.

[0076] The vehicle speed sensor 56 outputs a signal corresponding to the vehicle speed of the automobile 1. The SOC sensor 57 outputs a signal corresponding to the SOC of the high-voltage battery 9.

[0077] The controller 20 receives the signals output by these sensors via CAN 12. The controller 20 outputs control signals to the engine 4, inverter 7, K0 clutch 6, and automatic transmission 8 via CAN 12. In this way, the controller 20 controls the engine 4, motor 5, K0 clutch 6, and automatic transmission 8.

[0078] (Details of drive force control) Figure 3 shows a map 91 relating to the modes of vehicle 1. Vehicle 1 has an EV mode and an HEV mode. The EV mode is the Electric Vehicle mode, in which only the motor 5 outputs torque for driving vehicle 1. The HEV mode is the Hybrid Electric Vehicle mode, in which both the engine 4 and the motor 5 output torque for driving vehicle 1. When the engine water temperature is relatively high and the SOC of the high-voltage battery 9 is relatively high, vehicle 1 is in EV mode. Fuel efficiency is improved by using the power of the high-voltage battery 9. When the engine water temperature is low, vehicle 1 is in HEV mode. The engine coolant, whose temperature has risen due to the operation of engine 1, is used to heat the cabin. The energy efficiency of vehicle 1 is improved. When the SOC of the high-voltage battery 9 is relatively low, vehicle 1 is in HEV mode. The operation of engine 1 charges the high-voltage battery 9 while suppressing power consumption of the high-voltage battery 9. The SOC of the high-voltage battery 9 recovers.

[0079] The controller 20 stores the map 91. The controller 20 switches according to the map 91 whether to distribute the target torque of the vehicle 1 to both the target engine torque and the target motor torque (i.e., HEV mode), or to distribute the target torque of the vehicle 1 only to the target motor torque (i.e., EV mode).

[0080] In this vehicle 1, the ignition timing of engine 4 in HEV mode is basically MBT. Engine 4 operates at its best efficiency. Motor 5 assists engine 4, which is operating at its best efficiency.

[0081] Furthermore, if the catalytic converter of engine 4 is inactive and engine 4 is operating in AWS mode, the ignition timing will be retarded compared to MBT mode. This increases exhaust loss. In AWS mode, engine 4 can use the exhaust loss to activate the catalytic converter earlier. Motor 5 assists engine 4 in activating the catalytic converter.

[0082] Next, the torque distribution to the engine 4 and motor 5 in HEV mode will be explained with reference to Figure 4-7. Figure 4 shows the functional blocks of the controller 20. The controller 20 has a torque conversion unit 21, a torque arbitration unit 22, a torque distribution unit 23, an engine control unit 24, and a motor control unit 25 as functional blocks.

[0083] The torque conversion unit 21 receives a signal from the accelerator position sensor 51 and sets the target torque of the vehicle 1 based on the accelerator position. More specifically, the torque conversion unit 21 sets the target acceleration of the vehicle 1 based on the driver's accelerator operation and converts the set target acceleration to a target torque (i.e., the target torque of the vehicle 1) based on the vehicle speed of the vehicle 1 and the gear position of the automatic transmission 8.

[0084] The torque arbitration unit 22 receives a target torque based on the accelerator position set by the torque conversion unit 21, as well as torque request signals other than the accelerator position, and sets the final target torque. Torque request signals other than the accelerator position include, for example, torque request signals to stabilize the behavior of the automobile 1.

[0085] The torque distribution unit 23 receives the target torque of the vehicle 1 set by the torque arbitration unit 22, and distributes the final target torque to the target engine torque and the target motor torque. Note that when the vehicle 1 is in EV mode, the target engine torque is zero, and the target motor torque is equal to the target torque of the vehicle 1. The torque distribution unit 23 will be explained in detail later.

[0086] The engine control unit 24 outputs control signals corresponding to the target engine torque set by the torque distribution unit 23 to the engine 4, more specifically to the spark plug 41, injector 42, throttle valve 43, and intake S-VT 44. The engine 4 operates in such a way that the target engine torque is achieved.

[0087] The motor control unit 25 outputs a control signal to the inverter 7 that corresponds to the target motor torque set by the torque distribution unit 23. The motor 5 is controlled through the inverter 7. The motor 5 operates in such a way that the target motor torque is achieved. The target torque of the automobile 1 is achieved by the engine 4 outputting torque and the motor 5 outputting torque.

[0088] Figure 5 shows the functional blocks of the torque distribution unit 23. The torque distribution unit 23 has the following functional blocks: SOC management unit 231, first adder / subtractor 232, engine torque calculation unit 233, phase adjustment unit 234, second adder / subtractor 235, limiting unit 236, third adder / subtractor 237, and adder 238.

[0089] The SOC management unit 231 receives the final target torque of the automobile 1 set by the torque arbitration unit 22. The SOC management unit 231 also receives information about the high-voltage battery 9. The information about the high-voltage battery 9 includes at least the SOC of the high-voltage battery 9 based on the measurement signal from the SOC sensor 57, and the temperature of the high-voltage battery 9. Based on the target torque of the automobile 1 and the battery information, the SOC management unit 231 provisionally sets the target torque of the motor 5. For example, if the SOC is high, the SOC management unit 231 increases the target motor torque to increase the amount of assistance the motor 5 provides to the engine 4. For example, if the SOC is low, the SOC management unit 231 lowers the target motor torque in order to prioritize charging the high-voltage battery 9. The target motor torque set here corresponds to the steady-state target motor torque.

[0090] The first adder / subtractor 232 subtracts the target motor torque set by the SOC management unit 231 from the target torque of the automobile 1. The output of the first adder / subtractor 232 is the first target engine torque. The first target engine torque corresponds to the steady-state target engine torque. The first target engine torque can be rephrased as the torque achieved by adjusting the amount of air into the cylinder. The torque distribution unit 23 outputs the first target engine torque to the engine control unit 24.

[0091] When the driver operates the accelerator pedal 19, the target torque of the vehicle is changed. When the target torque of vehicle 1 is changed, the target engine torque and target motor torque are changed. When the target engine torque is changed, the target throttle opening and the target opening and closing timing of the intake valve are changed in order to change the amount of intake air into the cylinder. Changing the opening of the throttle valve 43 and / or changing the opening and closing timing of the intake valve by the intake S-VT 44 takes time, and it also takes time for the amount of intake air in the cylinder to actually change after the opening of the throttle valve 43 and the opening and closing timing of the intake valve have been changed. Furthermore, it takes time for the torque of engine 4 to actually change after the amount of intake air in the cylinder has actually changed. There is a time lag between when the driver operates the accelerator pedal 19 and when the torque of engine 4 is changed to the target engine torque.

[0092] The torque distribution unit 23 sets a target motor torque to compensate for the slow torque response of the engine 4. More specifically, the torque distribution unit 23 predicts the amount of intake air to the cylinders in the future, and based on the predicted intake air amount, predicts the torque of the engine 4 in the future. Based on the predicted torque of the engine 4, the torque distribution unit 23 sets a target motor torque so that the target torque of the vehicle 1 is achieved in the future.

[0093] During transient periods when the target torque changes, the SOC management unit 231 and the first adder / subtractor 232 of the torque distribution unit 23 are involved in setting the steady-state target engine torque, i.e., the first target engine torque. The engine torque calculation unit 233, phase adjustment unit 234, second adder / subtractor 235, limiting unit 236, third adder / subtractor 237, and adder 238 are involved in setting the transient target engine torque (the second target engine torque, described later) and the target motor torque.

[0094] The engine torque calculation unit 233 reads a predicted value for the amount of intake air into the cylinder in the future from the present moment. The engine control unit 24 performs the prediction of the intake air amount, as will be described later. The engine control unit 24 outputs a predicted value for the intake air amount after a predetermined reference time relative to the present moment. Based on the predicted intake air amount, the engine torque calculation unit 233 predicts the torque of the engine 4 in the future from the present moment. More specifically, based on the predicted intake air amount, the engine torque calculation unit 233 predicts the torque of the engine 4 when the spark plug 41 ignites at the optimal ignition timing determined from the operating state of the engine 4.

[0095] Here, an example of the optimal ignition timing is the MBT mentioned above. In other words, the engine torque calculation unit 233 predicts the torque of the engine 4 when the spark plug 41 ignites at MBT, based on the predicted intake air volume. Also, when the engine is operating in AWS mode, the optimal ignition timing is retarded compared to MBT. In other words, the engine torque calculation unit 233 may predict the torque of the engine 4 when the spark plug 41 ignites at a timing retarded compared to MBT, based on the predicted intake air volume.

[0096] The phase adjustment unit 234 synchronizes the torque changes of the engine 4 with those of the motor 5, taking into account, for example, the communication delay of the controller 20, the response delay of the motor 5, and the response delay of the engine 4. Generally, the torque response of the engine 4 is slower than that of the motor 5. The phase adjustment unit 234 adjusts the phase of the predicted torque value of the engine 4, taking into account the difference in torque response between the motor 5 and the engine 4.

[0097] Here, the torque response of engine 4 changes depending on the rotational speed of engine 4. That is, when the rotational speed of engine 4 is high, the combustion interval (i.e., time interval) between the multiple cylinders of engine 4 is short. When the rotational speed of engine 4 is low, the combustion interval (i.e., time interval) between the multiple cylinders is long. The time from when the amount of intake air to the cylinder changes until the torque of engine 4 changes also changes depending on the rotational speed of engine 4. When the rotational speed of engine 4 is high, the time from when the amount of intake air to the cylinder changes until the torque of engine 4 changes is short. When the rotational speed of engine 4 is low, the time from when the amount of intake air to the cylinder changes until the torque of engine 4 changes is long.

[0098] The engine control unit 24 predicts the intake air volume after a reference time (i.e., a certain period of time) relative to the current time. The timing at which the intake air volume after the reference time is reflected in the torque of the engine 4 varies depending on the rotational speed of the engine 4.

[0099] Figure 7 shows the relationship between engine speed and delay time. The delay time corresponds to the time lag between a change in intake air volume and a change in engine 4 torque. When the engine speed is low, the time it takes for a change in intake air volume to be reflected in a change in engine 4 torque is long. When the engine speed is low, the delay time is long. When the engine speed is high, the delay time is short. In Figure 7, the relationship between engine speed and delay time is set to a straight line such that the delay time decreases as the engine speed increases. The controller 20 stores the relationship shown in Figure 7. Note that the relationship between engine speed and delay time is not limited to the example shown. The relationship between engine speed and delay time is not limited to a straight line, but may also be a curve. Furthermore, the relationship between engine speed and delay time may also be stepwise.

[0100] The phase adjustment unit 234 sets a delay time based on the engine speed. The predicted intake air volume is reflected in the torque of the engine 4 after the delay time. The controller 20 predicts the torque of the engine 4 from the current time to the set time. The set time for torque prediction can be set to any time after the reference time for intake air volume prediction.

[0101] When the rotational speed of engine 4 exceeds the reference rotational speed r0, the delay time is zero. When the rotational speed of engine 4 is higher than the reference rotational speed r0, the responsiveness of the torque change of engine 4 to accelerator operation is sufficiently high, so there is no need to set a delay time. Even if the delay time is set to zero when the rotational speed of engine 4 is higher than the reference rotational speed, the controller 20 can accurately predict the torque of engine 4.

[0102] Furthermore, if the rotational speed of engine 4 exceeds the reference rotational speed, the torque response of engine 4 will become equivalent to that of motor 5, or the torque response of motor 5 will be slower than that of engine 4. Therefore, when the rotational speed of engine 4 is high, it is conceivable to speed up the torque response of motor 5 in order to synchronize the torque response of engine 4 and motor 5. However, when the rotational speed of engine 4 is high, the time required for one rotation of both engine 4 and motor 5 is short, so the torque response of engine 4 and motor 5 will be substantially synchronized even without speeding up the torque response of motor 5.

[0103] If the torque of engine 4 after a set time from the current time is predicted, the second adder / subtractor 235 subtracts the torque of engine 4 after the set time from the target torque of automobile 1. The predicted torque of engine 4 after the set time includes the delay in engine 4's torque response. If the output of the second adder / subtractor 235 is the target motor torque after the set time from the current time, the target torque of automobile 1 is achieved by adding the motor torque to the predicted torque of engine 4. In other words, the target motor torque compensates for the delay in engine 4's torque response.

[0104] The limiting unit 236 outputs a final target motor torque based on the target motor torque output by the second adder / subtractor 235, the maximum torque of motor 5, and the minimum torque. Here, the maximum motor torque and minimum motor torque are set according to the performance of motor 5, the temperature of motor 5, and / or the State of Charge (SOC) of the high-voltage battery 9. For example, if the SOC is high, motor 5 cannot perform regenerative operation, so the minimum motor torque is set to a small value. If the SOC is low, the high-voltage battery 9 must be charged, so the maximum motor torque is set to a small value. If the target motor torque output by the second adder / subtractor 235 exceeds the maximum motor torque, the limiting unit 236 sets the target motor torque to the maximum motor torque. If the target motor torque output by the second adder / subtractor 235 is less than the minimum motor torque, the limiting unit 236 sets the target motor torque to the minimum motor torque. If the target motor torque output by the second adder / subtractor 235 is less than or equal to the maximum motor torque and greater than or equal to the minimum motor torque, the limiting unit 236 sets the target motor torque output by the second adder / subtractor 235 as the final target motor torque.

[0105] The motor control unit 25 controls the motor 5 via the inverter 7 based on the target motor torque output by the limiting unit 236. As described above, the motor 5 outputs torque in conjunction with the engine 4 so that the target torque of the automobile 1 is achieved from the present time to a set time later. The torque changes of the engine 4 and the motor 5 are synchronized while suppressing the response delay of torque changes to the driver's operation of the accelerator pedal 19, thereby suppressing the discrepancy between the actual torque and the target torque.

[0106] In this case, if the limiting unit 236 limits the target motor torque to the minimum motor torque, the target motor torque output by the limiting unit 236 is greater than the target motor torque output by the second adder / subtractor 235. If the motor 5 continues to output the target motor torque (i.e., the minimum motor torque) and the engine 4 continues to output the target engine torque, the torque of the automobile 1 after the set time from the present will exceed the target torque.

[0107] The third adder / subtractor 237 calculates the difference between the target motor torque output by the second adder / subtractor 235 and the target motor torque output by the limiting unit 236. If the difference is zero, the limiting unit 236 is not limiting the target motor torque by the maximum or minimum motor torque. If the difference is not zero, the limiting unit 236 is limiting the target motor torque by the maximum or minimum motor torque.

[0108] The adder 238 sets the second target engine torque by adding the output of the third adder / subtractor 237 and the output of the engine torque calculation unit 233. The adder 238 outputs the second target engine torque to the engine control unit 24. The output of the third adder / subtractor 237 is the difference mentioned above, and the output of the engine torque calculation unit 233 is the torque of engine 4 predicted from the predicted intake air volume. The second target engine torque is related to the adjustment of the ignition timing. Specifically, if the target motor torque is limited by the minimum motor torque, the ignition timing is retarded from the optimal ignition timing (i.e., the ignition timing at MBT or AWS) so that the torque of engine 4 decreases. The second target engine torque is the torque achieved by adjusting the ignition timing and corresponds to the transient target engine torque.

[0109] The engine control unit 24 controls the intake air volume and ignition timing of the engine 4 based on the first target engine torque and the second target engine torque. If the ignition timing is retarded by the second target engine torque, the torque of the engine 4 decreases. The increase in motor torque is offset by the decrease in engine 4 torque. The torque of the vehicle 1, with the torque of the engine 4 and the torque of the motor 5, matches or substantially matches the target torque.

[0110] Furthermore, if the target motor torque is limited by the maximum motor torque, the torque of motor 5 will decrease relatively. The target torque of automobile 1 cannot be achieved unless the torque of engine 4 is increased. However, it is difficult to further increase the torque of engine 4 while it is operating at the optimal ignition timing. If the target motor torque is limited by the maximum motor torque in the limiting unit 236, no adjustment of the ignition timing is made.

[0111] (Prediction of engine intake air volume) Figure 6 shows the functional blocks of the engine control unit 24 related to predicting the intake air volume. The engine control unit 24 includes a throttle opening prediction unit 241, a throttle air volume prediction unit 242, a fourth adder / subtractor 243, an intake manifold air volume prediction unit 244, a pressure conversion unit 245, an S-VT change prediction unit 246, a charging efficiency prediction unit 247, and a multiplication unit 248. The engine control unit 24 predicts the intake air volume after a reference time relative to the current time. The reference time is a fixed period of time and is set in advance. The reference time can be arbitrarily set, for example, between 10 and several tens of milliseconds.

[0112] The throttle opening prediction unit 241 predicts the change in the opening of the throttle valve 43 over time based on the first target engine torque set by the torque distribution unit 23. Based on the target opening of the throttle valve 43 and the characteristic information of the throttle valve 43, the throttle opening prediction unit 241 predicts the opening of the throttle valve 43 from the present time to a reference time later. The relationship between the target engine torque and the target opening of the throttle valve 43 is stored in the controller 20. The characteristic information of the throttle valve 43 is also stored in the controller 20. The characteristics of the throttle valve 43 may be determined, for example, by conducting actual machine tests. As illustrated in Figure 6, the opening of the throttle valve 43 changes with a delay in response to the operation of the accelerator pedal 19.

[0113] The throttle airflow prediction unit 242 predicts the amount of air that will pass through the throttle valve 43 from the present time to a reference time. Specifically, the throttle airflow prediction unit 242 predicts the amount of air that will pass through the throttle valve 43 using Bernoulli's equation, based on the throttle opening prediction unit 241's prediction of the throttle valve 43's opening, the pressure in the intake manifold downstream of the throttle valve 43, and the intake pressure upstream of the throttle valve 43. The intake manifold pressure is a value converted to pressure by the pressure conversion unit 245 from the amount of air in the intake manifold from the present time to a reference time, as will be described later. The intake pressure upstream of the throttle valve 43 can be obtained, for example, from the measurement signal of the intake pressure sensor 52.

[0114] The fourth adder / subtractor 243 subtracts the amount of intake air into the cylinder, as described later, from the amount of air that will pass through the throttle valve 43 from the present time to a reference time, as predicted by the throttle air passage amount prediction unit 242.

[0115] The intake manifold air volume prediction unit 244 predicts the amount of air in the intake manifold from the present time to a reference time based on the output of the fourth adder / subtractor 243.

[0116] As described above, the pressure conversion unit 245 converts the amount of air in the intake manifold from the present time to a reference time, as predicted by the intake manifold air volume prediction unit 244, into the pressure in the intake manifold and outputs it to the throttle air volume prediction unit 242.

[0117] The S-VT change prediction unit 246, similar to the throttle opening prediction unit 241, predicts the change over time in the opening and closing timing of the intake valve due to the intake S-VT 44, based on the first target engine torque. The S-VT change prediction unit 246 predicts the opening and closing timing of the intake valve from the present time to a reference time later, based on the target opening and closing timing of the intake valve and the characteristic information of the intake S-VT 44. The relationship between the target engine torque and the target opening and closing timing of the intake valve is stored in the controller 20. The characteristic information of the intake S-VT 44 is also stored in the controller 20. The characteristics of the intake S-VT 44 may be determined, for example, by conducting actual machine tests. As illustrated in Figure 6, the opening and closing timing of the intake valve changes with a delay in response to the operation of the accelerator pedal 19.

[0118] The charging efficiency prediction unit 247 predicts the charging efficiency from the present time to a reference time, based on the timing of opening and closing the intake valve from the present time to a reference time, as predicted by the S-VT change prediction unit 246. The controller 20 has pre-stored a map showing the relationship between the timing of opening and closing the intake valve, the operating state of the engine 4, and the charging efficiency. The charging efficiency prediction unit 247 predicts the charging efficiency from the present time to a reference time, based on the map stored in the controller 20.

[0119] The multiplication unit 248 predicts the amount of intake air into the cylinder from the present time to the reference time by multiplying the amount of air in the intake manifold from the present time to the reference time, as predicted by the intake manifold air volume prediction unit 244, with the charging efficiency from the present time to the reference time, as predicted by the charging efficiency prediction unit 247. The predicted intake air volume is used for controlling the engine 4 and, as mentioned above, is output to the engine torque calculation unit 233 of the torque distribution unit 23.

[0120] (Control example) Figure 8 shows an example of control by the vehicle's drive force control device. The time chart in Figure 8 includes the operation of the accelerator pedal 19, the change in the target torque of vehicle 1, the change in the target intake air volume, the change in the predicted intake air volume, the change in the predicted engine torque value, the change in the target motor torque, and the change in ignition timing. This control example corresponds to the case where vehicle 1 is running in HEV mode and the driver presses the accelerator pedal 19 to accelerate vehicle 1.

[0121] First, at time t1, the driver presses the accelerator pedal 19. In response to this operation of the accelerator pedal 19, the torque conversion unit 21 and the torque adjustment unit 22 set a target torque for the automobile 1. This target torque is the torque achieved by the torque of the engine 4 and the torque of the motor 5. In the control example in Figure 8, the target torque increases in a stepwise manner at time t1.

[0122] The torque distribution unit 23 sets a target engine torque to correspond to the change in target torque. The target engine torque increases in a step-like manner, similar to the target torque. The target intake air volume of the engine 4 is set to correspond to the target engine torque. The target intake air volume also increases in a step-like manner at time t1. The opening of the throttle valve 43 changes so that the target intake air volume is achieved. As mentioned above, the change in the opening of the throttle valve 43 lags behind the operation of the accelerator pedal 19, so the throttle opening changes gradually over time, as illustrated by the dashed line in Figure 8.

[0123] As described above, the engine control unit 24 predicts the change in throttle opening and, based on that, predicts the intake air volume at a reference time relative to the current time. The predicted intake air volume gradually increases over time, starting from time t2, which is delayed from time t1, in accordance with the change in throttle opening.

[0124] The engine torque calculation unit 233 of the torque distribution unit 23 calculates the engine torque from the predicted intake air volume. The engine torque calculation unit 233 predicts the torque of the engine 4, for example, when the spark plug 41 ignites in MBT mode. The phase adjustment unit 234 adjusts the phase of the torque of the engine 4. In the control example in Figure 8, a delay time is set because the rotational speed of the engine 4 is relatively low. The predicted engine torque gradually increases with the passage of time, starting from time t3, which is delayed from time t1. Corresponding to the increase in intake air volume, the ignition timing changes from time t3 onward. Note that the ignition timing remains MBT even from time t3 onward.

[0125] The torque distribution unit 23 sets the target motor torque based on the target torque and the predicted engine torque value. The target motor torque is set so as to compensate for the delay in the torque change of the engine 4. Between times t1 and t3, the torque of the engine 4 does not change (i.e., the torque does not increase). Therefore, the target motor torque is achieved by increasing in a step-like manner at time t1. The response delay of the torque change of the automobile 1 to the operation of the accelerator pedal 19 is suppressed.

[0126] From time t3 onward, the target motor torque gradually decreases in response to the gradually increasing torque of engine 4. The torque changes of engine 4 and motor 5 are synchronized. This suppresses the discrepancy between the actual torque of vehicle 1 and the target torque. The target torque is achieved even after time t3.

[0127] Unlike in Figure 8, even when the driver releases the accelerator pedal 19 and the vehicle 1 decelerates, the motor 5 of this drive force control device compensates for the delay in the torque reduction of the engine 4. This suppresses the response delay of the torque change of the vehicle 1 to the operation of the accelerator pedal 19, and also suppresses the discrepancy between the actual torque of the vehicle 1 and the target torque. Furthermore, because the motor 5 compensates when the torque of the engine 4 is reduced, the engine 4 can reduce torque by reducing the intake air volume while maintaining MBT without retarding the ignition timing. This improves the fuel efficiency of the vehicle 1.

[0128] (modified version) Figure 9 shows a modified example of the torque distribution unit 230. Figure 9 shows some of the functional blocks of the torque distribution unit 230. The torque distribution unit 230 includes an SOC management unit 231, a first adder / subtractor 232 (omitted in Figure 9), an engine torque calculation unit 233, a phase adjustment unit 234, a second adder / subtractor 235, a limiting unit 236, a third adder / subtractor 237, an adder 238, and a second adder 239.

[0129] As described above, the engine torque calculation unit 233 predicts the torque of the engine 4 in the future based on the intake air volume predicted by the engine control unit 24. The phase adjustment unit 234 adjusts the phase of the torque of the engine 4 according to the rotational speed of the engine 4.

[0130] Unlike the second adder / subtractor 235 of the torque distribution unit 23 in Figure 5, the second adder / subtractor 235 calculates the difference between the predicted engine torque and the first target engine torque. The second adder / subtractor 235 calculates the delay in the torque response of the engine 4. This difference corresponds to the torque that the motor 5 should compensate for.

[0131] The second adder 239 adds the output of the second adder / subtractor 235 and the output of the SOC management unit 231. The output of the second adder / subtractor 235 is the difference between the predicted engine torque and the first target engine torque. The output of the SOC management unit 231 is the target motor torque set based on the target torque of the vehicle 1 and battery information, as described above. In other words, the second adder 239 corrects the target motor torque set by the SOC management unit 231 so that the delay in the torque response of the engine 4 is compensated for.

[0132] Furthermore, if the difference in the second adder / subtractor 235 is zero, the target motor torque set by the SOC management unit 231 will not be corrected.

[0133] The limiting unit 236 sets the final target motor torque in the same manner as described above, based on the target motor torque corrected by the second adder 239, the maximum motor torque, and the minimum motor torque. The third adder / subtractor 237 and adder 238 set the second target engine torque so that the torque of the engine 4 decreases when the target motor torque is limited by the minimum motor torque, as described above.

[0134] In the modified configuration, the target motor torque is set to compensate for the delay in the torque response of the engine 4, thereby suppressing the response delay of the torque change of the automobile 1 to the operation of the accelerator pedal 19. Furthermore, because it is based on a prediction of the engine 4's torque in the future rather than the present, the discrepancy between the actual torque and the target torque can be eliminated or substantially eliminated.

[0135] Figure 10 shows the basic control flow of the drive force control device having the torque distribution unit 230 shown in Figure 9. Note that some steps related to the functional blocks of the torque distribution unit 230 in Figure 9 are omitted in this control flow.

[0136] First, in step S11, the controller 20 reads the driver's accelerator operation based on the measurement signal from the accelerator position sensor 51. In the following step S12, the torque conversion unit 21 and the torque arbitration unit 22 set the target torque for the automobile 1.

[0137] In step S13, the SOC management unit 231 sets the target motor torque.

[0138] Meanwhile, in step S14, the first adder / subtractor 232 sets a target engine torque from the target torque of the automobile 1 and the target motor torque. In step S15, the engine control unit 24 sets target control values ​​for the throttle valve 43, injector 42, spark plug 41, and intake S-VT 44. In the subsequent step S16, the engine control unit 24 outputs control signals to the throttle valve 43, injector 42, spark plug 41, and intake S-VT 44 based on the target control values ​​set in step S15. The engine 4 is controlled by the controller 20.

[0139] In parallel with this control flow process, the engine torque calculation unit 233 and the phase adjustment unit 234 predict the engine torque in the future based on the target engine torque. In step S17, the predicted engine torque is read. In the following step S18, the difference between the predicted engine torque and the first target engine torque is calculated by the second adder / subtractor 235, and the controller 20 determines whether the predicted engine torque and the first target engine torque do not match. If the determination in step S18 is No, the process proceeds to step S19. If the determination in step S18 is Yes, the process proceeds to step S20.

[0140] In step S20, the controller 20 corrects the target motor torque at a set time relative to the current time. That is, the second adder 239 adds the difference between the predicted engine torque and the first target engine torque to the target motor torque.

[0141] In step S21, the controller 20 determines whether the set time for torque prediction of the engine 4 has been reached. If the determination in step S21 is No, the process repeats step S21; if the determination in step S21 is Yes, the process proceeds to step S22.

[0142] In step S22, the motor control unit 25 outputs a control signal related to the corrected target motor torque to the inverter 7. This synchronizes the torque change of the motor 5 with the torque change of the engine 4. The response delay of the torque change to the operation of the accelerator pedal 19 is suppressed, and the discrepancy between the target torque of the automobile 1 and the actual torque is suppressed. The target torque of the automobile 1 is achieved.

[0143] If the target motor torque is not corrected, the motor control unit 25 outputs a control signal related to the target motor torque set in step S13 to the inverter 7 in step S19. The motor 5 is controlled through the inverter 7 to achieve the target motor torque, and consequently the target torque of the automobile 1.

[0144] (summary) Therefore, the vehicle's drive force control device is A motor 5 that receives power and generates torque for vehicle propulsion, An engine 4 that burns fuel in the cylinder to generate torque for driving the vehicle, The system includes a controller 20 that receives an accelerator operation signal and outputs control signals corresponding to the accelerator operation to the motor 5 and the engine 4, The controller 20 sets a target torque for the vehicle corresponding to the accelerator operation (torque conversion unit 21, torque arbitration unit 22), distributes the target engine torque from the vehicle's target torque according to a predetermined distribution rule (torque distribution units 23, 230), and outputs a control signal to the engine 4 corresponding to the target engine torque (engine control unit 24). The controller 20 predicts the amount of intake air to the cylinder in the future based on the target engine torque (engine control unit 24, Figure 6), and predicts the torque of the engine 4 after a set time from the present based on the predicted intake air amount (engine torque calculation unit 233, phase adjustment unit 234). The controller 20 sets a target motor torque after a set time (second adder / subtractor 235, limiter 236, second adder 239) based on the predicted torque of the engine 4 after a set time so that the target torque of the vehicle is achieved, and outputs a control signal corresponding to the target motor torque to the motor 5 (motor control unit 25), thereby synchronizing the torque response of the engine 4 and the torque response of the motor 5.

[0145] Because the highly responsive motor 5 compensates for the response delay of the engine 4, this drive force control device suppresses the response delay of torque changes in response to accelerator operation.

[0146] Furthermore, since the target motor torque is set based on the predicted future engine torque, the torque response of the engine and the motor are synchronized in this drive force control system. This drive force control system can eliminate, or substantially eliminate, the discrepancy between the actual torque and the target torque.

[0147] In predicting the torque of the engine 4, the controller 20 delays the change in the torque of the engine 4 in response to the predicted change in intake air volume when the rotational speed of the engine 4 is low, compared to when the rotational speed of the engine 4 is high (phase adjustment unit 234, Figure 7).

[0148] The controller 20 can accurately predict changes in the torque of engine 4 in the future, rather than in the present time.

[0149] The controller 20 shortens the delay time related to torque changes as the rotational speed of the engine 4 increases, and sets the delay time to zero when the rotational speed of the engine 4 is higher than the reference rotational speed r0 (phase adjustment unit 234, Figure 7).

[0150] The accuracy of predicting the torque of engine 4 in the future will be improved compared to the present. Also, because the rotational speed of engine 4 is high, the controller 20 can accurately predict the torque of engine 4 even if the delay time is zero.

[0151] The controller 20 sets the target motor torque to compensate for the difference between the predicted torque of the engine 4 and the target engine torque (second adder 235, second adder 239, Figure 9).

[0152] Motor 5 can compensate for the response delay of engine 4.

[0153] The controller 20 predicts the torque of the engine 4 from the present time to a set time later, based on the predicted intake air volume and the optimal ignition timing determined from the operating state of the engine 4 (engine torque calculation unit 233, phase adjustment unit 234).

[0154] Motor 5 can adequately assist engine 4.

[0155] The controller 20 sets the target motor torque to be greater than or equal to the minimum torque that the motor 5 can generate (limiting unit 236), When the target motor torque is limited by the minimum torque, the controller 20 retards the ignition timing of the engine 4 compared to the optimal ignition timing so that the torque of the engine 4 decreases (third adder / subtractor 237, adder 238).

[0156] This prevents the vehicle's torque from exceeding the target torque.

[0157] The controller 20 is Based on the target engine torque, the change in the opening degree of the throttle valve 43 of the engine 4 after accelerator operation is predicted (throttle opening degree prediction unit 241), Based on the predicted opening degree of the throttle valve 43 and the pressure of the intake manifold of the engine 4, the amount of air passing through the throttle valve 43 is predicted (throttle air passage amount prediction unit 242). The amount of air in the intake manifold is predicted from the predicted amount of air passing through the throttle valve 43 (intake manifold air volume prediction unit 244), The amount of intake air to the cylinder is predicted from the predicted amount of air in the intake manifold (multiplication unit 248).

[0158] The controller 20 can predict the amount of intake air to the cylinders in the future rather than the present moment.

[0159] The controller 20 is Based on the target engine torque, the change in the opening and closing timing of the intake valve of the engine 4 after accelerator operation is predicted (S-VT change prediction unit 246), Based on the predicted opening and closing timing of the intake valve, the filling efficiency is predicted (filling efficiency prediction unit 247), The amount of intake air to the cylinder is predicted from the predicted filling efficiency and the predicted amount of air in the intake manifold (multiplication unit 248).

[0160] The controller 20 can accurately predict the amount of intake air to the cylinders in the future, rather than the present moment. [Explanation of Symbols]

[0161] 4 engines 5 Motors 20 controllers 43 Throttle valve

Claims

1. A motor that receives power and generates torque for vehicle propulsion, An engine that generates torque for vehicle propulsion by burning fuel in a cylinder, The system includes a controller that receives an accelerator operation signal and outputs a control signal corresponding to the accelerator operation to the motor and the engine, The controller sets a target torque for the vehicle corresponding to the accelerator operation, distributes the target engine torque from the vehicle's target torque according to a predetermined distribution rule, and outputs a control signal to the engine corresponding to the target engine torque. The controller predicts the amount of intake air to the cylinder in the future based on the target engine torque, and predicts the engine torque at a set time from the present based on the predicted amount of intake air. The controller sets a target motor torque after a set time based on the predicted engine torque after the set time so that the target torque of the vehicle is achieved, and synchronizes the torque response of the engine and the torque response of the motor by outputting a control signal corresponding to the target motor torque to the motor so that there is no discrepancy between the actual torque and the target torque. The controller is a vehicle drive force control device that, in predicting the torque of the engine, delays the change in the torque of the engine in response to the predicted change in intake air volume when the engine speed is low compared to when the engine speed is high.

2. In the vehicle drive force control device according to claim 1, The controller is a vehicle drive force control device that shortens the delay time related to torque changes as the engine speed increases, and sets the delay time to zero when the engine speed is higher than a reference speed.

3. In the vehicle drive force control device according to claim 1, The controller is a vehicle drive force control device that sets the target motor torque to compensate for the difference between the predicted engine torque and the target engine torque.

4. In the vehicle drive force control device according to claim 1, The controller is a vehicle drive force control device that predicts the torque of the engine from the present time to a set time later, based on the predicted intake air volume and the optimal ignition timing determined from the operating state of the engine.

5. In the vehicle drive force control device according to claim 4, The controller sets the target motor torque to be equal to or greater than the minimum torque that the motor can generate. The controller is a vehicle drive force control device that, when the target motor torque is limited by the minimum torque, retards the ignition timing of the engine compared to the optimal ignition timing so that the torque of the engine decreases.

6. In the vehicle drive force control device according to claim 1, The aforementioned controller, Based on the aforementioned target engine torque, the change in the opening degree of the engine's throttle valve after accelerator operation is predicted. Based on the predicted change in the throttle valve opening and the pressure in the engine's intake manifold, the amount of air passing through the throttle valve is predicted. From the predicted amount of air passing through the throttle valve, the amount of air in the intake manifold Predict the amount of air, A vehicle drive force control device that predicts the amount of intake air to the cylinder from the predicted amount of air in the intake manifold.

7. In the vehicle drive force control device according to claim 6, The aforementioned controller, Based on the aforementioned target engine torque, the change in the opening and closing timing of the engine's intake valve after accelerator operation is predicted. From the predicted opening and closing timing of the intake valve, the filling efficiency is predicted. A vehicle drive force control device that predicts the amount of intake air to the cylinder based on the predicted charging efficiency and the predicted amount of air in the intake manifold.

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