Hybrid vehicle control device

Abstract

To provide a control device of a hybrid vehicle which can prevent unnecessary warming of a catalyst and improve fuel consumption performance.SOLUTION: An ECU performs catalyst warming control, changeover control for switching an electric travel mode and a hybrid travel mode according to driver request torque and a calculation of a start prediction point in which engine start is predicted and arrival prediction time t (D) to be required time until attaining the start prediction point. The ECU calculates warming completion time, catalyst performance holding time, and catalyst warming effective time when executing the catalyst warming control when starting the engine on the basis of the driver request torque (step S2). The ECU prohibits the catalyst warming control and stops the engine (step S6) when the arrival prediction time t (D) is equal to and more than the catalyst warming effective time t (C) (YES in step S4) and when a condition for switching to the electric travel mode on the basis of the driver request torque is established (YES in step S5).SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In a hybrid vehicle equipped with an engine and an electric motor as a driving source, a technology is known, described in Patent Document 1, that predicts the timing when the engine will need to be operated, and starts the engine in advance to complete the warm-up of the catalyst before that timing.

[0003] The hybrid vehicle described in Patent Document 1 prohibits engine start for catalyst warm-up when the EV driving range calculated from the battery's state of charge is greater than the driving distance to the destination obtained from the navigation device, since the destination can be reached using only the driving power of the electric motor. Furthermore, even when catalyst warm-up is prohibited, the hybrid vehicle described in Patent Document 1 is configured to cancel the prohibition of catalyst warm-up if an engine start request is made. This allows the hybrid vehicle described in Patent Document 1 to appropriately warm up the catalytic converter when catalyst warm-up is required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-120333 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology described in Patent Document 1, when the engine is started in response to a sudden increase in driver-requested torque while driving in EV mode to a destination, the prohibition on catalyst warm-up is lifted, so it is conceivable that the engine operation will continue for the purpose of warming up the catalyst when the driver-requested torque subsequently decreases and engine driving force is no longer needed.For this reason, with the technology described in Patent Document 1, if the engine operation is continued after engine driving force is no longer needed to complete catalyst warm-up, the destination may be reached without using engine driving force, and fuel economy may deteriorate due to unnecessary catalyst warm-up.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device for a hybrid vehicle that can prevent unnecessary warm-up of a catalyst and improve fuel economy. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a control device for a hybrid vehicle, which includes an engine and an electric motor as drive sources, a catalyst for purifying exhaust gas from the engine, and an acquisition unit for acquiring a travel route from a current position to a set destination position, and which switches between an electric travel mode in which operation of the engine is stopped and the vehicle travels using motor torque of the electric motor, and a hybrid travel mode in which the vehicle travels using engine torque of the engine and motor torque of the electric motor, and which includes catalyst warm-up control for operating the engine until a catalyst temperature of the catalyst rises to a predetermined warm-up completion temperature and stopping operation of the engine when the catalyst temperature rises to the warm-up completion temperature, switching control for switching between the electric travel mode and the hybrid travel mode in accordance with a driver's requested torque, and a control unit for switching between the electric travel mode and the hybrid travel mode at a point on the travel route where the engine is predicted to be started for switching to the hybrid travel mode. The control unit calculates a predicted start point and a predicted arrival time, which is the time predicted to be required to reach the predicted start point from a current location, and when the engine is started due to the satisfaction of a condition for switching to the hybrid driving mode based on the driver requested torque, the control unit calculates a warm-up completion time, which is the time required for the catalyst temperature to rise to the warm-up completion temperature when the catalyst warm-up control is executed, a catalyst performance retention time, which is the time required for the catalyst temperature to fall to a lower limit temperature at which exhaust gas purification performance can be maintained after rising to the warm-up completion temperature, and a catalyst warm-up effective time, which is the sum of the warm-up completion time and the catalyst performance retention time, and when the predicted arrival time is equal to or longer than the catalyst warm-up effective time and the condition for switching to the electric driving mode based on the driver requested torque is satisfied, the control unit prohibits the execution of the catalyst warm-up control. [Effects of the Invention]

[0008] As described above, according to the present invention, it is possible to provide a control device for a hybrid vehicle that can prevent unnecessary warm-up of the catalyst and improve fuel economy. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle equipped with a control device for a hybrid vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing the operation of the control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 3] FIG. 3 is a time chart showing the transition of the vehicle state when the engine is started in response to an increase in driver requested torque in a situation where the predicted arrival time is sufficiently long in a control device for a hybrid vehicle according to one embodiment of the present invention. [Figure 4] FIG. 4 is a time chart showing the transition of the vehicle state when the engine is started in response to an increase in driver requested torque in a situation where the predicted arrival time is relatively short in a control device for a hybrid vehicle according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] A control device for a hybrid vehicle according to one embodiment of the present invention includes an engine and an electric motor as drive sources, a catalyst that purifies exhaust gas from the engine, and an acquisition unit that acquires a travel route from a current position to a set destination position, and switches between an electric travel mode in which operation of the engine is stopped and the vehicle travels using motor torque of the electric motor, and a hybrid travel mode in which the vehicle travels using engine torque of the engine and motor torque of the electric motor. The control device for a hybrid vehicle according to one embodiment of the present invention includes catalyst warm-up control that operates the engine until the catalyst temperature of the catalyst rises to a predetermined warm-up completion temperature and stops operation of the engine when the catalyst temperature rises to the warm-up completion temperature, switching control that switches between the electric travel mode and the hybrid travel mode in accordance with driver request torque, and start of the engine for switching to the hybrid travel mode on the travel route. The control unit calculates a predicted start point, which is a predicted location where the engine is to start, and a predicted arrival time, which is a predicted time required to reach the predicted start point from the current location, when the engine is started due to a condition for switching to the hybrid driving mode based on the driver's requested torque being satisfied. The control unit calculates a warm-up completion time, which is the time required for the catalyst temperature to rise to a warm-up completion temperature when catalyst warm-up control is executed, a catalyst performance maintenance time, which is the time required for the catalyst temperature to fall to a lower limit temperature at which exhaust gas purification performance can be maintained after the warm-up completion temperature has been reached, and an effective catalyst warm-up time, which is the sum of the warm-up completion time and the catalyst performance maintenance time. If the predicted arrival time is equal to or greater than the effective catalyst warm-up time and the condition for switching to the electric driving mode based on the driver's requested torque is satisfied, the control unit for a hybrid vehicle according to one embodiment of the present invention can prevent unnecessary warm-up of the catalyst and improve fuel economy. [Example]

[0011] A vehicle equipped with a control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In Fig. 1, a vehicle 1 according to an embodiment of the present invention includes an engine 2 as a drive source, a motor generator 3 which is an electric motor also as a drive source, a battery 31 which exchanges electric power with the motor generator 3, a transmission 4, a differential 5, drive wheels 6, and an ECU (Electronic Control Unit) 10 as a control unit.

[0012] The engine 2 is formed with a plurality of cylinders. In this embodiment, the engine 2 is configured to perform a series of four strokes for each cylinder, including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

[0013] The engine 2 is equipped with a catalyst 2A that purifies exhaust gas. The catalyst 2A has the characteristic of exhibiting purification performance when the catalyst temperature is equal to or higher than its activation temperature.

[0014] An ISG (Integrated Starter Generator) 20 is connected to the engine 2. The ISG 20 is connected to the crankshaft of the engine 2 via a belt 21 or the like. The ISG 20 functions as an electric motor that rotates when supplied with electric power to drive the engine 2, and also functions as a generator that converts the rotational force input from the crankshaft into electric power.

[0015] The motor generator 3 has a function of being driven by power supplied from a battery 31 via an inverter 30, and a function of performing regenerative power generation by a reverse driving force input from the differential 5.

[0016] Under the control of the ECU 10, the inverter 30 converts DC power supplied from the battery 31 into three-phase AC power and supplies it to the motor generator 3, and also converts the three-phase AC power generated by the motor generator 3 into DC power to charge the battery 31. The battery 31 is formed of a secondary battery such as a lithium-ion battery.

[0017] The transmission 4 changes the speed of the rotation output from the engine 2 at a gear ratio corresponding to one of a plurality of gear stages and outputs the rotation. In this embodiment, the transmission 4 is configured as an AMT (Automated Manual Transmission) that automates the gear shifting operation based on the structure of a parallel shaft gear type manual transmission.

[0018] The gears of the transmission 4 are changed by a shift actuator 44. The shift actuator 44 is connected to and controlled by the ECU 10. The output shaft of the transmission 4 is connected to left and right drive wheels 6 via a differential 5. The output shaft of the motor generator 3 is connected to the output shaft of the transmission 4. In this way, the vehicle 1 is configured as a hybrid vehicle that can run using the driving force of at least one of the engine 2 and the motor generator 3.

[0019] The gears that can be established in the transmission 4 include, for example, forward gears ranging from a low 1st gear to a high 5th gear, and a reverse gear. The number of driving gears varies depending on the specifications of the vehicle 1 and is not limited to the above-mentioned 1st to 5th gears. The transmission 4 is equipped with a synchronization mechanism (synchro-mesh) not only for the forward gears but also for the reverse gears.

[0020] The gears in the transmission 4 are changed according to the operating position of a shift lever 40 operated by the driver. The operating position of the shift lever 40 is detected by a shift position sensor 41. The shift position sensor 41 is connected to the ECU 10 and transmits the detection result to the ECU 10.

[0021] In this embodiment, the operating positions of the shift lever 40 include a P range which is a parking position, an R range which is a reverse position, an N range which is a neutral position, and a D range which is a forward position.

[0022] For example, when the driver sets the shift lever 40 to the D range, the ECU 10 drives the shift actuator 44 and the clutch actuator 70 in response to the detection signal of the accelerator opening sensor 91, etc., to shift between each of the forward gears from 1st to 5th gear.

[0023] Furthermore, when the driver shifts the shift lever 40 from the D range to the R range, the ECU 10 drives the shift actuator 44 and the clutch actuator 70 to change the gear from the forward gear to the reverse gear.

[0024] The D-range and R-range in this embodiment are shift positions at which the vehicle can be driven, and constitute the driving positions of the present invention. The P-range and N-range are shift positions at which the engine 2 can be started, and constitute the starting positions of the present invention.

[0025] The transmission 4 is provided with a neutral switch 42. The neutral switch 42 is connected to the ECU 10. The neutral switch 42 detects a state in which no gear position is established in the transmission 4, that is, a neutral state, and is turned on when the transmission 4 is in a neutral state.

[0026] A clutch 7 is provided in the power transmission path between the engine 2 and the transmission 4. For example, a friction clutch can be used as the clutch 7. The engine 2 and the transmission 4 are connected via the clutch 7. The clutch 7 can be set to transmit or not transmit power between the engine 2 and the drive wheels 6. The clutch 7 constitutes a power transmission mechanism in the present invention.

[0027] In this way, power is transmitted to the transmission 4 from the engine 2 via the clutch 7, and the transmission 4 is configured to be able to change gears by shifting. The clutch 7 is equipped with a clutch disc, and the clutch disc and the input shaft of the transmission 4 are interconnected and rotate at a constant speed. Therefore, the rotation speed of the clutch disc (hereinafter referred to as the rotation speed of the clutch 7) is equal to the rotation speed of the input shaft of the transmission 4.

[0028] The clutch 7 is operated by a clutch actuator 70 and can be switched between an engaged state in which power is transmitted between the engine 2 and the motor generator 3, a disengaged state in which power is not transmitted, and a half-clutch state in which torque is transmitted with a rotational difference. The clutch actuator 70 is connected to and controlled by the ECU 10.

[0029] The clutch 7 is provided with a clutch rotation speed sensor 43, which detects the rotation speed of the clutch 7. The clutch rotation speed sensor 43 is connected to the ECU 10 and transmits the detection result to the ECU 10. The clutch rotation speed sensor 43 does not detect the rotation direction of the clutch 7.

[0030] The ECU 10 controls the clutch actuator 70 in accordance with the depression amount of the clutch pedal 71 operated by the driver, so as to perform an operation equivalent to that of a manual clutch.

[0031] The depression amount of the clutch pedal 71 is detected by a clutch pedal sensor 72. The clutch pedal sensor 72 is connected to the ECU 10 and transmits a signal corresponding to the depression amount of the clutch pedal 71 to the ECU 10.

[0032] The vehicle 1 is equipped with an accelerator pedal 90 that is operated by the driver. The amount of depression of the accelerator pedal 90 is detected by an accelerator opening sensor 91. The accelerator opening sensor 91 is connected to the ECU 10, detects the amount of depression of the accelerator pedal 90 as an accelerator opening, and transmits a signal corresponding to the accelerator opening to the ECU 10.

[0033] The vehicle 1 is equipped with a brake pedal 92 that is operated by the driver. The amount of depression of the brake pedal 92 is detected by a brake pedal sensor 93. The brake pedal sensor 93 is connected to the ECU 10 and transmits a signal corresponding to the amount of depression of the brake pedal 92 to the ECU 10.

[0034] The vehicle 1 is equipped with a navigation device 12. The navigation device 12 is equipped with a GPS (Global Positioning System) that measures the current position of the vehicle 1 and a storage device that stores a map, and calculates the driving route and distance from the current position to a set destination position. The navigation device 12 can be an in-vehicle navigation device or a smartphone with a navigation function.

[0035] The ECU 10 is composed of a computer unit having a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), flash memory for storing backup data, etc., input ports, and output ports.

[0036] The ROM of the computer unit stores various constants, various maps, and the like, as well as a program for causing the computer unit to function as the ECU 10. That is, the CPU executes the program stored in the ROM using the RAM as a work area, causing the computer unit to function as the ECU 10 in this embodiment.

[0037] In addition to the above-mentioned sensors, a vehicle speed sensor 11 is connected to the ECU 10. The vehicle speed sensor 11 detects the speed of the vehicle 1 and transmits the detection result to the ECU 10.

[0038] The ECU 10 is configured to switch the control mode of the vehicle 1. In this embodiment, an electric driving mode and a hybrid driving mode are set as the control modes.

[0039] The electric driving mode is a control mode in which the operation of the engine 2 is stopped and the vehicle 1 is driven by the motor torque of the motor generator 3. In this electric driving mode, the motor generator 3 is controlled so that the driver's requested torque is satisfied by the motor torque of the motor generator 3. In addition, in this electric driving mode, the clutch 7 is released.

[0040] The hybrid driving mode is a control mode in which the vehicle 1 is driven by the engine torque of the engine 2 and the motor torque of the motor generator 3. In this hybrid driving mode, the vehicle 1 is driven by only the engine torque, or by both the engine torque and the motor torque. For example, in the hybrid driving mode, the motor generator 3 and the engine 2 are controlled so that the driver requested torque is satisfied by the combined torque of the motor torque of the motor generator 3 and the engine torque of the engine 2. Note that the situation in which the vehicle 1 is driven by the combined torque includes a situation in which the engine torque compensates for the shortfall in the motor torque relative to the driver requested torque, and a situation in which the motor torque compensates for the shortfall in the engine torque relative to the driver requested torque. In this hybrid driving mode, the clutch 7 is engaged.

[0041] A navigation device 12 is connected to the ECU 10. The ECU 10 acquires the travel route and distance from the current position to the destination position from the navigation device 12. The ECU 10 constitutes an acquisition unit in the present invention.

[0042] The ECU 10 switches between the electric drive mode and the hybrid drive mode based on the driver requested torque determined from the accelerator opening and engine speed, and the state of charge (SOC) of the battery 31.

[0043] When the depression amount of accelerator pedal 90 increases while the electric driving mode is in operation and the maximum motor torque of motor generator 3 according to the state of charge of battery 31 is no longer able to satisfy the driver's requested torque, ECU 10 switches to hybrid driving mode. When switching to hybrid driving mode is performed, engine 2 is started. In hybrid driving mode, engine 2 and motor generator 3 are controlled so that the combined torque of engine torque of engine 2 and motor torque of motor generator 3 satisfies the driver's requested torque.

[0044] Furthermore, when the depression amount of the accelerator pedal 90 decreases while the hybrid driving mode is being implemented and the driver's requested torque can be satisfied by the maximum motor torque of the motor generator 3 according to the state of charge of the battery 31, the ECU 10 switches to the electric driving mode. When the mode is switched to the hybrid driving mode, the engine 2 is stopped.

[0045] The ECU 10 performs catalyst warm-up control, which is a control for operating the engine 2 until the catalyst temperature of the catalyst 2A rises to a predetermined warm-up completion temperature T(H), and stopping the operation of the engine 2 when the catalyst temperature rises to the warm-up completion temperature T(H).

[0046] As described above, the vehicle 1 of this embodiment is a hybrid vehicle that runs by switching between electric driving mode and hybrid driving mode, and therefore the engine 2 is operated intermittently. Therefore, when the driving mode is switched from electric driving mode to hybrid driving mode and the engine 2 is started, the temperature of the catalyst 2A is not necessarily raised to the activation temperature, and if the temperature of the catalyst 2A is low at the start of hybrid driving, the exhaust gas purification performance may deteriorate. Here, exhaust gas purification performance refers to the performance of purifying exhaust gas.

[0047] Therefore, in order to prevent deterioration of exhaust gas purification performance, it is desirable to perform catalyst warm-up control prior to the timing when it is predicted that the drive mode will be switched from electric to hybrid, thereby raising the temperature of catalyst 2A to a temperature above its activation temperature (hereinafter also referred to as warming up catalyst 2A), so that the exhaust gas purification performance of catalyst 2A can be fully demonstrated from the start of hybrid drive mode.

[0048] Therefore, in this embodiment, the ECU 10 calculates the timing of arrival at the point where switching to hybrid driving mode is predicted based on multiple pieces of information including the driving route to the destination location obtained from the navigation device 12, and performs catalyst warm-up control prior to that arrival timing.

[0049] Specifically, the ECU 10 calculates a predicted start point, which is a point on the travel route where the engine 2 is predicted to start in order to switch to the hybrid travel mode, and a predicted arrival time t(D), which is a predicted required time from the current location to the predicted start point.The ECU 10 then performs catalyst warm-up control before the predicted arrival time t(D) becomes zero (i.e., before the vehicle reaches the predicted start point).

[0050] The predicted start point is determined mainly based on the state of charge of the battery 31, the road load on the travel route (road conditions such as uphill roads), and the state of the motor generator 3 or the inverter 30 on the travel route. For example, the ECU 10 determines, as the predicted start point, a point where the state of charge of the battery 31 is predicted to drop to a predetermined value. Furthermore, the ECU 10 determines, as the predicted start point, a point where the road load on the travel route is predicted to exceed the maximum motor torque of the motor generator 3 based on the road load (road conditions such as uphill roads). Furthermore, the ECU 10 determines, as the predicted start point, a point where the temperature of the motor generator 3 or the inverter 30 is predicted to reach a high temperature equal to or higher than a predetermined temperature, for example.

[0051] Here, when the driver's depression amount of accelerator pedal 90 increases and it becomes necessary to compensate for the shortage of motor torque relative to the driver-requested torque with engine torque, ECU 10 determines that the conditions for switching to the hybrid driving mode are met, starts engine 2, and switches to the hybrid driving mode. On the other hand, when the driver's depression amount of accelerator pedal 90 decreases and it becomes unnecessary to compensate for the shortage of motor torque relative to the driver-requested torque with engine torque, ECU 10 determines that the conditions for switching to the electric driving mode are met, stops engine 2, and switches to the electric driving mode. Because starting and stopping of engine 2 in response to driver-requested torque occurs according to the driver's depression amount of accelerator pedal 90, it is difficult to predict the start and stop timing in advance. Furthermore, starting and stopping of engine 2 in response to driver-requested torque may occur before the vehicle reaches the predicted start point.

[0052] If catalyst warm-up control is executed after the conditions for switching to electric driving mode are met (if engine 2 continues to operate until catalyst 2A warm-up is complete), exhaust gas purification performance may or may not be maintained sufficiently until the predicted start point is reached. If catalyst warm-up control is executed but exhaust gas purification performance cannot be maintained sufficiently until the predicted start point is reached, unnecessary warm-up of catalyst 2A will result in fuel consumption, and fuel economy will deteriorate.

[0053] In this embodiment, when the engine 2 is started due to the satisfaction of a condition for switching to the hybrid driving mode based on the driver's requested torque, the ECU 10 calculates the following when executing catalyst warm-up control: a warm-up completion time t(A) that is the time required for the catalyst temperature to rise to a warm-up completion temperature T(H); a catalyst performance retention time t(B) that is the time required for the catalyst temperature to fall to a lower limit temperature T(L) at which the exhaust gas purification performance can be maintained after rising to the warm-up completion temperature T(H); and a catalyst warm-up effective time t(C) that is the sum of the warm-up completion time t(A) and the catalyst performance retention time t(B). Here, the lower limit temperature T(L) is, for example, the activation temperature of the catalyst 2A.

[0054] The ECU 10 calculates the warm-up completion time t(A), the catalyst performance retention time t(B), and the catalyst warm-up effective time t(C) only while the engine 2 is operating. The ECU 10 calculates the warm-up completion time t(A) based on at least one of the warm-up completion temperature T(H), the current catalyst temperature, the outside air temperature, the vehicle speed on the planned travel route, and the driving force of the vehicle 1. The ECU 10 calculates the catalyst performance retention time t(B) based on the difference between the warm-up completion temperature T(H) and the lower limit temperature T(L), the outside air temperature, and the vehicle speed on the planned travel route.

[0055] Then, when the predicted arrival time t(D) is equal to or longer than the effective catalyst warm-up time t(C) and the condition for switching to the electric driving mode based on the driver requested torque is met, the ECU 10 prohibits the execution of catalyst warm-up control.

[0056] On the other hand, when the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C) and the condition for switching to the electric driving mode based on the driver requested torque is met, the ECU 10 permits the execution of catalyst warm-up control.

[0057] Furthermore, when ECU 10 permits execution of catalyst warm-up control, it may estimate a catalyst performance retention time t(E) after engine stop, which is the time required for the catalyst temperature to drop to the lower limit temperature T(L) if engine 2 is stopped, and may stop engine 2 when the predicted arrival time t(D) becomes shorter than catalyst performance retention time t(E) after engine stop. ECU 10 can estimate catalyst performance retention time t(E) after engine stop based on the fact that the rate of decrease (slope) of the catalyst temperature is constant when engine 2 is stopped.

[0058] There is a certain correlation between the catalyst temperature and the engine water temperature of the engine 2. Therefore, the ECU 10 may store threshold values ​​of the engine water temperature corresponding to the warm-up completion temperature T(H) and the lower limit temperature T(L), and may compare these threshold values ​​with the engine water temperature to determine whether or not to perform catalyst warm-up control.

[0059] Specifically, the ECU 10 calculates a warm-up completion time t(A) as the time required for the engine water temperature of the engine 2 to rise to a water temperature corresponding to the warm-up completion temperature T(H), calculates a catalyst performance retention time t(B) as the time required for the engine water temperature to fall to a water temperature corresponding to the lower limit temperature T(L), and calculates an effective catalyst warm-up time t(C) as the sum of the warm-up completion time t(A) based on the engine water temperature and the catalyst performance retention time t(B).The ECU 10 then determines whether or not to perform catalyst warm-up control based on the engine water temperature instead of the catalyst temperature.

[0060] The control operation performed by the control device according to this embodiment configured as above will be described with reference to Fig. 2. This operation is repeatedly executed in short cycles.

[0061] 2, in step S1, ECU 10 determines whether or not an engine start condition is satisfied. If the engine start condition is satisfied, the process proceeds to step S2. If the engine start condition is not satisfied, the process ends. The engine start condition is a condition for transitioning from electric driving mode to hybrid driving mode, and is determined, for example, based on the state of charge of battery 31 and the amount of operation of accelerator pedal 90 by the driver. If the driver requested torque calculated from the amount of operation of accelerator pedal 90 is equal to or greater than the maximum motor torque of motor generator 3 estimated from the state of charge of battery 31, etc., ECU 10 determines in step S1 that the engine start condition is satisfied, and starts engine 2 in step S2.

[0062] After starting the engine 2 in step S2, the ECU 10 determines in step S3 whether a destination location and a planned route to the destination location are set in the navigation device 12, and if they are set, the process proceeds to step S4, and if they are not set, the process proceeds to step S7.

[0063] In step S4, ECU 10 calculates the predicted start point of engine 2 and the predicted arrival time t(D), which is the time required from the current location to reach that predicted start point.If the predicted arrival time t(D) is equal to or greater than the effective catalyst warm-up time t(C), ECU 10 proceeds to step S5, and if the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C), ECU 10 proceeds to step S7.

[0064] In step S5, the ECU 10 determines whether the engine stop condition A is satisfied. If the engine stop condition A is satisfied, the ECU 10 proceeds to step S6, and if the engine stop condition A is not satisfied, the ECU 10 returns to step S3.

[0065] Engine stop condition A is a condition for stopping engine 2 in order to transition to electric driving mode, and does not include a requirement for warming up catalyst 2A. Engine stop condition A is determined, for example, based on the state of charge of battery 31 and the amount of operation of accelerator pedal 90 by the driver. If the driver requested torque calculated from the amount of operation of accelerator pedal 90 is less than the maximum motor torque of motor generator 3 estimated from the state of charge of battery 31, etc., ECU 10 determines in step S5 that engine stop condition A is met, proceeds to step S6, stops engine 2, and ends the current operation.

[0066] In this way, when the predicted arrival time t(D) is equal to or longer than the effective catalyst warm-up time t(C) (YES in step S4) and the engine stop condition A, which is the condition for switching to the electric driving mode based on the driver requested torque, is met (YES in step S5), the ECU 10 prohibits the execution of catalyst warm-up control (operation of the engine 2 to warm up the catalyst 2A).

[0067] In step S7, the ECU 10 determines whether the engine stop condition B is met, and if the engine stop condition B is met, the ECU 10 proceeds to step S6, and if the engine stop condition B is not met, the ECU 10 returns to step S3.

[0068] The engine stop condition B is a normal engine stop condition for transitioning to the electric driving mode, and includes a requirement for warming up the catalyst 2A. In other words, the engine stop condition B is a condition that adds conditions for warming up the catalyst 2A, such as the temperature of the catalyst 2A and the engine water temperature, to the engine stop condition A. For example, if the engine stop condition A is met and the temperature of the catalyst 2A is equal to or higher than the lower limit temperature T(L) that can ensure exhaust gas purification performance, the ECU 10 determines that the engine stop condition B is met, proceeds to step S6, stops the engine 2, and ends the current operation.

[0069] In this way, when the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C) (NO in step S4), even if the engine stop condition A, which is a condition for switching to the electric driving mode based on the driver requested torque, is satisfied, the ECU 10 permits the execution of catalyst warm-up control. Then, even after the engine stop condition A is satisfied, the ECU 10 continues to operate the engine 2 to warm up the catalyst 2A, and stops the engine 2 when the engine stop condition B, which includes a requirement for warming up the catalyst 2A, is satisfied.

[0070] The transition of the vehicle state when such a control operation of ECU 10 is being executed will be described with reference to Figures 3 and 4. The vertical axes of Figures 3 and 4, from top to bottom, represent catalyst temperature, engine operation or stop, whether engine stop condition A (referred to as condition A in the figures) is met or not, and whether engine stop condition B (referred to as condition B in the figures) is met or not, and the horizontal axes represent the passage of time.

[0071] First, referring to Fig. 3, a description will be given of the transition of the vehicle state when engine 2 is started in response to an increase in driver-requested torque due to depression of accelerator pedal 90 in a situation where the predicted time t(D) for engine 2 to reach the predicted start point is sufficiently long. Note that, for the exhaust gas temperature in Fig. 3, the actual temperature when engine 2 is stopped at time t1 is represented by a solid line as the actual catalyst temperature, and the temperature when engine 2 continues to operate until time t2 to warm up catalyst 2A is represented by a dashed line as the predicted catalyst temperature value.

[0072] 3, at time t0, the engine 2 has been started by depressing the accelerator pedal 90, and the vehicle 1 is running in hybrid driving mode. Furthermore, neither the engine stop condition A nor the engine stop condition B is satisfied. Furthermore, the catalyst temperature is rising due to the operation of the engine 2.

[0073] At this time t0, the ECU 10 starts calculating the warm-up completion time t(A), the catalyst performance retention time t(B), and the catalyst warm-up effective time t(C), and starts comparing the predicted arrival time t(D) with the catalyst warm-up effective time t(C). These calculations are performed continuously from the time the engine 2 is started until it is stopped.

[0074] Then, at time t1, the predicted arrival time t(D) is equal to or longer than the effective catalyst warm-up time t(C) and engine stop condition A is met, so engine 2 is stopped and the mode is switched from hybrid driving mode to electric driving mode. At time t1, the catalyst temperature (actual catalyst temperature) begins to drop due to engine 2 being stopped.

[0075] Here, the effective catalyst warm-up time t(C) at time t1 is a time calculated from the predicted catalyst temperature (predicted catalyst temperature value) if catalyst warm-up control (operation of engine 2 to warm up catalyst 2A) is continued after time t1. In FIG. 3, if catalyst warm-up control is continued after time t1, the predicted catalyst temperature will reach the warm-up completion temperature T(H) at time t2, after the warm-up completion time t(A) has elapsed since time t1, and catalyst warm-up control will end (engine 2 will be stopped). The predicted catalyst temperature will continue to decrease after time t2 and will become less than the lower limit temperature T(L) at time t3, after the catalyst performance retention time t(B) has elapsed since time t2.

[0076] 3, it is predicted that the vehicle 1 will reach the predicted start point and the engine 2 will start at time t4, which is a time after the predicted arrival time t(D) has elapsed since time t2, but it is predicted that the estimated catalyst temperature will be below the lower limit temperature T(L) at time t3, which is before time t4. Therefore, even if the catalyst warm-up control is continued until time t2 without stopping the engine 2 at time t1, it is not possible to maintain the estimated catalyst temperature at or above the lower limit temperature T(L) until time t4, when the predicted start point is reached.

[0077] 3, the predicted arrival time t(D) is equal to or longer than the effective catalyst warm-up time t(C) throughout the entire period during which the engine 2 is operating (the period from time t0 to time t1), so the engine 2 is stopped at time t1 when the engine stop condition A is met. Note that the catalyst temperature drops when the engine 2 is stopped at time t1, but rises when the engine 2 is started at time t4 when the predicted start point is reached.

[0078] Next, referring to Fig. 4, a description will be given of the transition of the vehicle state when engine 2 is started in response to an increase in driver-requested torque due to depression of accelerator pedal 90 in a situation where the predicted time t(D) for engine 2 to reach the predicted start point is relatively short. Note that for the exhaust gas temperature in Fig. 4, the solid line represents the actual temperature when engine 2 is stopped at time t12, and the dashed line represents the temperature when engine 2 is stopped between times t11 and t12.

[0079] 4, at time t10, the engine 2 has been started by depressing the accelerator pedal 90, and the vehicle 1 is running in hybrid driving mode. Furthermore, neither the engine stop condition A nor the engine stop condition B is satisfied. Furthermore, the catalyst temperature is rising due to the operation of the engine 2.

[0080] At time t10, the ECU 10 starts calculating the warm-up completion time t(A), catalyst performance retention time t(B), and catalyst warm-up effective time t(C), and comparing the predicted arrival time t(D) with the catalyst warm-up effective time t(C). These calculations are performed continuously from the time the engine 2 is started until it is stopped.

[0081] Thereafter, at time t11, engine stop condition A is met, but since the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C), engine 2 is not stopped and operation of engine 2 continues to warm up catalyst 2A.

[0082] Thereafter, at time t12, the catalyst temperature rises to the warm-up completion temperature T(H). Also, at time t12, the predicted arrival time t(D) is shorter than the effective catalyst warm-up time t(C). In other words, time t13, at which the predicted arrival time t(D) has elapsed since time t12, is before time t14, at which the effective catalyst warm-up time t(C) has elapsed since time t12. Also, engine stop condition B is met at time t12. Therefore, engine 2 is stopped at time t12, and a switch from hybrid driving mode to electric driving mode is performed. At time t12, with engine 2 being stopped, the catalyst temperature begins to drop. The catalyst temperature remains higher than the lower limit temperature T(L) even at time t13, at which the predicted arrival time t(D) has elapsed, and drops to below the lower limit temperature T(L) at time t14, at which the effective catalyst warm-up time t(C) has elapsed.

[0083] As described above, in FIG. 4, since the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C) during the entire period during which engine 2 is operating (the period from time t10 to time t12), engine 2 is not stopped even if engine stop condition A is met, but is stopped when engine stop condition B is met.

[0084] Here, even if the catalyst temperature is not higher than the lower limit temperature T(L) at time t13 when the start of engine 2 is predicted, exhaust gas purification performance can be ensured as long as the catalyst temperature coincides with the lower limit temperature T(L). Therefore, it is not necessarily necessary to continue operating engine 2 until the catalyst temperature rises to the warm-up completion temperature T(H).

[0085] Therefore, when ECU 10 permits the execution of catalyst warm-up control, it may estimate the catalyst performance retention time t(E) after engine stop, which is the time required for the catalyst temperature to drop to the lower limit temperature T(L) if engine 2 is stopped, and may stop engine 2 when the predicted arrival time t(D) becomes less than the catalyst performance retention time t(E) after engine stop.

[0086] In other words, if ECU 10 allows catalyst warm-up control and continues operating engine 2 to warm up catalyst 2A after time t11, ECU 10 may stop engine 2 when the predicted arrival time t(D) becomes less than the catalyst performance retention time t(E) after engine stop, even if it is before time t12 when the catalyst temperature rises to the warm-up completion temperature T(H).

[0087] As described above, in this embodiment, the ECU 10 as a control unit performs catalyst warm-up control, which operates the engine 2 until the catalyst temperature of the catalyst 2A rises to a predetermined warm-up completion temperature T(H) and stops the operation of the engine 2 when the catalyst temperature rises to the warm-up completion temperature T(H); switching control, which switches between the electric driving mode and the hybrid driving mode according to the driver's required torque; and calculation of a predicted start point, which is a point on the driving route where the engine 2 is predicted to start in order to switch to the hybrid driving mode, and a predicted arrival time t(D), which is a predicted required time from the current location to reach the predicted start point.

[0088] When the engine 2 is started due to the satisfaction of the conditions for switching to the hybrid driving mode based on the driver's requested torque, the ECU 10 calculates the warm-up completion time t(A), which is the time required for the catalyst temperature to rise to the warm-up completion temperature T(H), the catalyst performance retention time t(B), which is the time required for the catalyst temperature to fall to the lower limit temperature T(L) at which the exhaust gas purification performance can be maintained after rising to the warm-up completion temperature T(H), and the catalyst warm-up effective time t(C), which is the sum of the warm-up completion time t(A) and the catalyst performance retention time t(B).

[0089] Then, when the predicted arrival time t(D) is equal to or longer than the effective catalyst warm-up time t(C) and the condition for switching to the electric driving mode based on the driver requested torque is met, the ECU 10 prohibits the execution of catalyst warm-up control.

[0090] As a result, if the predicted arrival time t(D) until the predicted start point is equal to or longer than the effective catalyst warm-up time t(C) and the conditions for switching to electric driving mode are met, even if engine 2 operation is continued until warm-up of catalyst 2A is complete, sufficient exhaust gas purification performance cannot be maintained until the predicted start point at which engine 2 is started after warm-up is complete. However, in this embodiment, fuel consumption can be reduced by prohibiting catalyst warm-up control and stopping engine 2. As a result, unnecessary warm-up of catalyst 2A can be prevented, and fuel economy can be improved.

[0091] In addition, in this embodiment, when the predicted arrival time t(D) is less than the effective catalyst warm-up time t(C) and the condition for switching to the electric driving mode based on the driver requested torque is met, the ECU 10 permits the execution of catalyst warm-up control.

[0092] As a result, if the predicted arrival time t(D) until the predicted start point is less than the effective catalyst warm-up time t(C) and the conditions for switching to electric driving mode are met, it is possible to maintain sufficient exhaust gas purification performance even after warm-up of the catalyst 2A is complete until the predicted point at which the engine 2 is started. Therefore, by executing catalyst warm-up control, it is possible to improve exhaust gas purification performance in hybrid driving mode.

[0093] Furthermore, in this embodiment, when ECU 10 permits the execution of catalyst warm-up control, it estimates the catalyst performance retention time t(E) after engine stop, which is the time required for the catalyst temperature to drop to the lower limit temperature T(L) if engine 2 is stopped, and stops engine 2 when the predicted arrival time t(D) becomes shorter than the catalyst performance retention time t(E) after engine stop.

[0094] As a result, even before the catalyst temperature of catalyst 2A rises to warm-up completion temperature T(H), engine 2 is stopped if the predicted arrival time t(D) becomes less than the catalyst performance retention time t(E) after engine stop, thereby shortening the time required to operate engine 2 to warm up catalyst 2A and improving fuel efficiency.

[0095] In this embodiment, the ECU 10 calculates a warm-up completion time t(A) as the time required for the engine water temperature of the engine 2 to rise to a water temperature corresponding to the warm-up completion temperature T(H), calculates a catalyst performance retention time t(B) as the time required for the engine water temperature to fall to a water temperature corresponding to the lower limit temperature T(L), and calculates an effective catalyst warm-up time t(C) as the sum of the warm-up completion time t(A) based on the engine water temperature and the catalyst performance retention time t(B).The ECU 10 then determines whether or not to perform catalyst warm-up control based on the engine water temperature instead of the catalyst temperature.

[0096] As a result, by determining whether or not to perform catalyst warm-up control based on the engine water temperature, control related to the warm-up of catalyst 2A and control related to the operation of engine 2 can be carried out using the engine water temperature, which is closely related to the fuel efficiency of engine 2, thereby achieving both the exhaust gas purification performance of catalyst 2A and the fuel efficiency of engine 2.

[0097] In this embodiment, the hybrid vehicle 1 is also provided with a navigation device 12 that calculates a travel route based on the set destination position. The ECU 10 then acquires the travel route from the navigation device 12.

[0098] This allows the navigation device 12 to calculate the travel route, thereby reducing the calculation load on the ECU 10.

[0099] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0100] 1 vehicle (hybrid vehicle) 2 engines 2A catalyst 3 Motor generator (electric motor) 10 ECU (acquisition unit, control unit) 12 Navigation devices t(A) Warm-up time t(B) Catalyst performance retention time t(C) Catalyst warm-up effective time t(D) arrival predicted time T(H) Warm-up temperature T(L) lower limit temperature

Claims

1. an engine and an electric motor as a driving source; a catalyst for purifying exhaust gas from the engine; an acquisition unit that acquires a travel route from the current location to the set destination location, A control device for a hybrid vehicle that switches between an electric driving mode in which operation of the engine is stopped and the vehicle travels using motor torque of the electric motor, and a hybrid driving mode in which the vehicle travels using engine torque of the engine and motor torque of the electric motor, a catalyst warm-up control that operates the engine until a catalyst temperature of the catalyst rises to a predetermined warm-up completion temperature, and stops the operation of the engine when the catalyst temperature rises to the warm-up completion temperature; switching control for switching between the electric driving mode and the hybrid driving mode in accordance with a driver requested torque; a control unit that calculates a start prediction point, which is a point on the travel route where the engine is predicted to be started for switching to the hybrid travel mode, and a predicted arrival time, which is a required time predicted to be required to reach the start prediction point from a current location, The control unit When the engine is started due to the satisfaction of a condition for switching to the hybrid driving mode based on the driver requested torque, a warm-up completion time, which is the time required for the catalyst temperature to rise to the warm-up completion temperature when the catalyst warm-up control is executed; a catalyst performance maintenance time, which is the time required for the catalyst temperature to fall to a lower limit temperature at which the exhaust gas purification performance can be maintained after rising to the warm-up completion temperature; and a catalyst warm-up effective time, which is the sum of the warm-up completion time and the catalyst performance maintenance time; a control device for a hybrid vehicle, characterized in that, when the predicted arrival time is equal to or longer than the catalyst warm-up effective time and a condition for switching to the electric driving mode based on the driver requested torque is satisfied, execution of the catalyst warm-up control is prohibited.

2. The control unit 2. The control device for a hybrid vehicle according to claim 1, wherein when the predicted arrival time is less than the catalyst warm-up effective time and a condition for switching to the electric driving mode based on the driver requested torque is satisfied, execution of the catalyst warm-up control is permitted.

3. The control unit 3. The control device for a hybrid vehicle according to claim 2, wherein, when execution of the catalyst warm-up control is permitted, a catalyst performance retention time after engine stop, which is the time required for the catalyst temperature to drop to the lower limit temperature if the engine is stopped, is estimated, and when the predicted arrival time becomes shorter than the catalyst performance retention time after engine stop, the engine is stopped.

4. The control unit calculating the warm-up completion time as a time required for the engine water temperature of the engine to rise to a water temperature corresponding to the warm-up completion temperature; calculating the catalyst performance retention time as the time required for the engine water temperature to decrease to the water temperature corresponding to the lower limit temperature; calculating the effective catalyst warm-up time as a sum of the warm-up completion time based on the engine water temperature and the catalyst performance maintenance time; 4. The vehicle control device according to claim 1, wherein the determination as to whether or not to perform the catalyst warm-up control is based on the engine water temperature instead of the catalyst temperature.

5. a navigation device that calculates the travel route based on the set destination position, The vehicle control device according to any one of claims 1 to 4, wherein the acquisition unit acquires the travel route from the navigation device.

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