Vehicle control device

Abstract

To provide a vehicular controller which can ensure a time for warming up a catalyst and can suppress a deterioration in exhaust gas performance even in the case of shifting to hybrid traveling with an increase in driver request torque.SOLUTION: An ECU calculates, as a torque differential value, a value obtained by subtracting, from driver request torque, the maximum torque of a motor generator at least according to the charge state of a battery. Then, during the execution of an electric traveling mode, if the torque differential value is equal to or greater than a first prescribed value, the ECU switches to a hybrid traveling mode. Furthermore, during the execution of the electric traveling mode (YES in Step S1), if a catalyst temperature is equal to or lower than a prescribed temperature threshold, and the torque differential value is equal to or greater than a second prescribed value less than the first prescribed value (YES in Step S2), the ECU executes catalyst warming-up control to start an engine and warm up a catalyst (Step S3).SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Document 1 describes a technique for suppressing deterioration of exhaust gas performance by starting an internal combustion engine to warm up a catalyst when the catalyst is below the activation temperature in a hybrid vehicle including an internal combustion engine and an electric motor capable of outputting driving power.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technique described in Patent Document 1, in a situation where the internal combustion engine is started and the vehicle shifts to hybrid driving because the driver demand torque exceeds the maximum torque of the electric motor during electric driving, there is a problem that the time for warming up the catalyst cannot be ensured, resulting in deterioration of exhaust gas performance.

[0005] Therefore, an object of the present invention is to provide a vehicle control device that can ensure the catalyst warm-up time and suppress deterioration of exhaust gas performance even when shifting to hybrid driving as the driver demand torque increases.

Means for Solving the Problems

[0006] To solve the above problems, the present invention provides a vehicle control device for controlling a vehicle including an engine and an electric motor as drive sources, a catalyst for purifying exhaust gas of the engine, and a battery for exchanging power with the electric motor. The control device includes a control unit that switches between an electric driving mode in which the engine operation is stopped and the vehicle runs on the power of the electric motor, and a hybrid driving mode in which the vehicle runs on the power of the engine and the electric motor. and a power transmission mechanism capable of setting power transmission between the engine and the drive wheels to transmission or non - transmission; The control unit calculates, as a torque difference value, a value obtained by subtracting the maximum torque of the electric motor corresponding at least to the state of charge of the battery from the driver required torque. During the execution of the electric driving mode, when the torque difference value is equal to or greater than a first predetermined value, the control unit switches to the hybrid driving mode. During the execution of the electric driving mode, when the catalyst temperature of the catalyst is equal to or lower than a predetermined temperature threshold and the torque difference value is equal to or greater than a second predetermined value that is smaller than the first predetermined value, the control unit starts the engine and performs catalyst warm-up control to warm up the catalyst. and during the execution of the catalyst warm - up control, setting the power transmission mechanism to non - transmission; This is the gist of the present invention.

Advantages of the Invention

[0007] As described above, according to the present invention, even when shifting to hybrid driving as the driver required torque increases, it is possible to provide a vehicle control device that can secure the catalyst warm-up time and suppress deterioration of exhaust gas performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to an embodiment of the present invention controls a vehicle including an engine and an electric motor as drive sources, a catalyst that purifies the exhaust gas of the engine, and a battery that exchanges power with the electric motor. The vehicle control device is provided with a control unit that switches between an electric driving mode in which the engine operation is stopped and the vehicle runs on the power of the electric motor, and a hybrid driving mode in which the vehicle runs on the power of the engine and the electric motor. The control unit calculates, as a torque difference value, a value obtained by subtracting the maximum torque of the electric motor corresponding at least to the state of charge of the battery from the driver required torque. During the execution of the electric driving mode, when the torque difference value is equal to or greater than a first predetermined value, a switch to the hybrid driving mode is made. During the execution of the electric driving mode, when the catalyst temperature of the catalyst is equal to or lower than a predetermined temperature threshold and the torque difference value is equal to or greater than a second predetermined value smaller than the first predetermined value, a catalyst warm-up control for starting the engine and warming up the catalyst is performed. Thereby, the vehicle control device according to an embodiment of the present invention can secure the warm-up time of the catalyst and suppress the deterioration of the exhaust gas performance even when shifting to hybrid driving as the driver required torque increases.

EXAMPLE

[0010] Hereinafter, with reference to the drawings, a vehicle equipped with the control device according to the embodiment of the present invention will be described in detail.

[0011] 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 that is an electric motor as a drive source, a battery 31 that exchanges 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 has a plurality of cylinders formed therein. In the present embodiment, the engine 2 is configured to perform a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder.

[0013] The engine 2 is provided with a catalyst 2A for purifying exhaust gas. The catalyst 2A has the characteristic of exhibiting purification performance when the catalyst temperature is equal to or higher than the 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 has a function of an electric motor that rotationally drives the engine 2 by rotating when power is supplied, and a function of 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 electric power supplied from the 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] The inverter 30, under the control of the ECU 10, converts the DC power supplied from the battery 31 into three-phase AC power and supplies it to the motor generator 3, or converts the three-phase AC power generated by the motor generator 3 into DC power to charge the battery 31. The battery 31 is composed of a secondary battery such as a lithium-ion battery, for example.

[0017] The transmission 4 shifts and outputs the rotation output from the engine 2 at a gear ratio corresponding to any of a plurality of gear positions. In this embodiment, the transmission 4 is configured by an AMT (Automated Manual Transmission) that automates the shifting operation based on the structure of a parallel-axis gear type manual transmission.

[0018] The gear positions of the transmission 4 are switched by a shift actuator 44. The shift actuator 44 is connected to the ECU 10 and is controlled by the ECU 10. The output shaft of the transmission 4 is connected to the 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 travel by the driving force of at least one of the engine 2 and the motor generator 3.

[0019] The gear positions achievable with the transmission 4 include, for example, forward gear positions from the first gear position, which is a low speed gear position, to the fifth gear position, which is a high speed gear position, and a reverse gear position. The number of gear positions for driving varies depending on the specifications of the vehicle 1 and is not limited to the above-mentioned first gear position to fifth gear position. The transmission 4 is provided with a synchronization mechanism (synchromesh) not only for forward gear positions but also for reverse gear positions.

[0020] The gear positions in the transmission 4 are switched according to the operation position of a shift lever 40 operated by the driver. The operation 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 operation position of the shift lever 40 is provided with 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 according to the detection signal of the accelerator opening sensor 91 or the like, and performs shifting between the forward gears from the first gear to the fifth gear.

[0023] Also, when the driver switches 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, and performs a shift stage switching from the forward gear stage to the reverse gear stage.

[0024] The D range and the R range in this embodiment are shift positions where the vehicle can run, and constitute the running positions in the present invention. Also, the P range and the N range in the present invention are shift positions where the engine 2 can be started, and constitute the starting positions in 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 where none of the gear stages are established in the transmission 4, that is, a neutral state, and is a switch that is turned on when the transmission 4 is in the neutral state.

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

[0027] In this way, the transmission 4 has power transmitted from the engine 2 via the clutch 7 and is configured to be able to switch gear ratios by a shift operation. The clutch 7 includes a clutch disk, and the clutch disk and the input shaft of the transmission 4 are interconnected and rotate at the same speed. Therefore, the rotational speed of the clutch disk (hereinafter referred to as the rotational speed of the clutch 7) is equal to the rotational speed of the input shaft of the transmission 4.

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

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

[0030] The ECU 10 controls the clutch actuator 70 according to the depression amount of the clutch pedal 71 operated by the driver and controls it so as to achieve the same operation as 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] Vehicle 1 is equipped with an accelerator pedal 90 operated by the driver. The depression amount 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 depression amount of the accelerator pedal 90 as the accelerator opening, and transmits a signal corresponding to the accelerator opening to the ECU 10.

[0033] Vehicle 1 is equipped with a brake pedal 92 operated by the driver. The depression amount 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 depression amount of the brake pedal 92 to the ECU 10.

[0034] The ECU 10 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port.

[0035] In the ROM of the computer unit, a program for causing the computer unit to function as the ECU 10 is stored together with various constants and various maps. That is, when the CPU executes the program stored in the ROM using the RAM as a work area, the computer unit functions as the ECU 10 in this embodiment.

[0036] In addition to the above-described sensors, a vehicle speed sensor 11 is connected to the ECU 10. The vehicle speed sensor 11 detects the vehicle speed of the vehicle 1 and transmits the detection result to the ECU 10.

[0037] The ECU 10 is configured to switch the control mode of the vehicle 1. As the control modes in this embodiment, an electric driving mode and a hybrid driving mode are set.

[0038] The electric driving mode is a control mode in which the operation of the engine 2 is stopped and the vehicle runs with the power of the motor generator 3. In this electric driving mode, the clutch 7 is released.

[0039] The hybrid driving mode is a control mode in which the vehicle runs with the power of the engine 2 and the power of the motor generator 3. In this hybrid driving mode, the vehicle 1 runs by the power of the engine 2, or the power of the engine 2 and the motor generator 3. In the hybrid driving mode, the clutch 7 is engaged.

[0040] The ECU 10 switches between the electric driving mode and the hybrid driving mode based on the driver required torque determined from the accelerator opening and the engine speed.

[0041] The ECU 10 calculates, as a torque difference value, a value obtained by subtracting the maximum torque of the motor generator 3 corresponding at least to the state of charge of the battery 31 from the driver required torque.

[0042] Here, the maximum torque of the motor generator 3 is a variable value determined according to the state of charge (SOC: State of Charge) of the battery 31 at that time, the degree of deterioration (SOH: State of Health) of the battery 31, the battery cell temperature, the element temperature of the inverter 30, the rotation speed of the motor generator 3, etc. For example, the higher the battery cell temperature, the greater the discharge capacity of the battery 31 and the greater the maximum torque of the motor generator 3. The ECU 10 stores a map used for calculating the maximum torque of the motor generator 3. The map used for calculating the maximum torque includes a map defining the correlation between the value representing the rotation speed of the motor generator 3 converted into the vehicle speed and the value representing the maximum torque converted into the axle torque.

[0043] During the execution of the electric driving mode, if the torque difference value is equal to or greater than a first predetermined value, ECU 10 switches to the hybrid driving mode. When the switch to the hybrid driving mode is made, engine 2 is started. In the hybrid driving mode, engine 2 and motor generator 3 are controlled such that the combined torque of the engine torque of engine 2 and the motor torque of motor generator 3 satisfies the driver required torque.

[0044] As described above, since vehicle 1 of this embodiment is a hybrid vehicle that switches between an electric driving mode and a hybrid driving mode and travels, engine 2 is intermittently operated. Therefore, when the switch from the electric driving mode to the hybrid driving mode is made and engine 2 is started, the catalyst 2A is not always heated up to the activation temperature. When the temperature of catalyst 2A is low at the start of hybrid driving, the exhaust gas performance may deteriorate. Here, the exhaust gas performance refers to the performance of purifying exhaust gas.

[0045] Therefore, in order to suppress the deterioration of the exhaust gas performance, when the situation is such that the driver required torque is large, etc., since it is assumed that the switch from the electric driving mode to the hybrid driving mode will be made thereafter, it is desirable to pre-heat catalyst 2A to the activation temperature before switching to the hybrid driving mode (hereinafter, also referred to as preheating of catalyst 2A).

[0046] Therefore, in this embodiment, during the execution of the electric driving mode, when the catalyst temperature of catalyst 2A is equal to or lower than a predetermined temperature threshold value and the torque difference value is equal to or greater than a second predetermined value that is smaller than the first predetermined value, ECU 10 performs catalyst warm-up control to start engine 2 and warm up catalyst 2A.

[0047] The temperature threshold value of catalyst 2A is a value determined based on, for example, the activation temperature of catalyst 2A. The catalyst temperature of catalyst 2A being equal to or lower than the predetermined temperature threshold value means that catalyst 2A is in a state where the temperature is equal to or lower than the activation temperature.

[0048] The second predetermined value is a variable value determined based on the current catalyst temperature. The ECU 10 stores a map defining the correlation between the catalyst temperature and the second predetermined value, and calculates the second predetermined value with reference to this map. In the map for calculating the second predetermined value, the second predetermined value is set to be smaller as the catalyst temperature is lower. Therefore, the higher the current catalyst temperature, the less likely it is for the condition that the torque difference value is equal to or greater than the second predetermined value to be satisfied, and it becomes less likely to perform the catalyst warm-up control for starting the engine 2 for warming up the catalyst 2A.

[0049] Also, in the present embodiment, when the torque difference value is less than a third predetermined value that is smaller than the second predetermined value during the operation of the engine 2, the ECU 10 stops the engine 2. The third predetermined value is set to be smaller as the catalyst temperature is lower. Note that the operation of the engine 2 includes not only the case where the engine 2 is operated by the catalyst warm-up control during the execution of the electric driving mode, but also the case where the engine 2 is operated as a drive source during the execution of the hybrid driving mode.

[0050] Also, in the present embodiment, the ECU 10 may calculate, as the torque difference value, a value obtained by subtracting the maximum torque of the motor generator 3 corresponding at least to the state of charge of the battery 31 from the driver request torque corresponding to a predetermined accelerator pedal depression amount that is half or more of the maximum value.

[0051] That is, the driver request torque used for calculating the torque difference value is not limited to the driver request torque based on the actual current depression amount of the accelerator pedal 90, and may be a predetermined driver request torque assuming a situation where the driver depresses the accelerator pedal 90 significantly. The driver request torque corresponding to a predetermined accelerator pedal depression amount that is half or more of the maximum value is a driver request torque assuming a situation where the driver depresses the accelerator pedal 90 significantly. In this case, the driver request torque becomes a value corresponding to an accelerator pedal depression amount of, for example, 80% or the like.

[0052] Note that the accelerator pedal depression amount used to calculate the driver required torque may be a variable value according to the current driving environment of the vehicle 1 (such as road surface slope). For example, when the vehicle 1 is driving on an uphill road, it is assumed that the driver depresses the accelerator pedal 90 more deeply than when driving on a flat road. Therefore, the driver required torque may be calculated using an accelerator pedal depression amount of 90% instead of 80%.

[0053] Also, in this embodiment, the ECU 10 sets the clutch 7 as a power transmission mechanism to non-transmission during the execution of the catalyst warm-up control. Therefore, during the execution of the catalyst warm-up control, the engine 2 is operated for warming up the catalyst 2A, and the power of the engine 2 is not used as a driving source for driving.

[0054] The catalyst warm-up operation by the control device according to this embodiment configured as described above will be described with reference to FIG. 2. This catalyst warm-up operation is repeatedly executed in a short cycle.

[0055] In step S1, the ECU 10 determines whether or not the electric driving mode is being executed.

[0056] If the ECU 10 determines in step S1 that the electric driving mode is being executed, in step S2, it determines whether or not a torque difference value, which is a value obtained by subtracting the maximum torque of the motor generator 3 (denoted as T(E) in the figure) from the driver required torque (denoted as T(D) in the figure), is greater than or equal to a second predetermined value (denoted as T(TH) in the figure).

[0057] If the torque difference value is not greater than or equal to the second predetermined value, the ECU 10 ends the current operation.

[0058] If the torque difference value is greater than or equal to the second predetermined value, the ECU 10 starts the engine 2 in step S3 and ends the current operation. When the engine 2 is started, the catalyst 2A is warmed up to the activation temperature.

[0059] When the ECU 10 determines in step S1 that it is not in the electric driving mode, it determines in step S4 whether or not the engine stop condition is satisfied. When the torque difference value is less than the third predetermined value during the operation of the engine 2, the ECU 10 determines that the engine stop condition is satisfied.

[0060] When the ECU 10 determines in step S4 that the engine stop condition is not satisfied, it ends the current operation.

[0061] When the ECU 10 determines in step S4 that the engine stop condition is satisfied, it stops the engine 2 in step S5 and ends the current operation. Note that the stop of the engine 2 due to the satisfaction of the engine stop condition may be performed not only in the situation where the engine 2 is being operated by the catalyst warming control during the execution of the electric driving mode, but also in the situation where the engine 2 is being operated as a drive source during the execution of the hybrid driving mode.

[0062] The transition of the vehicle state during the execution of such a catalyst warming operation will be described with reference to FIGS. 3 and 4. The vertical axes of FIGS. 3 and 4 represent, from top to bottom, vehicle speed, driver required torque, maximum torque of the motor generator 3, torque difference value (denoted as the difference in torque values in the figure), catalyst temperature, engine drive state, and power transmission state. The horizontal axes of FIGS. 3 and 4 represent the passage of time.

[0063] Referring to FIG. 3, the transition of the vehicle state when shifting to hybrid driving after the execution of the catalyst warming operation will be described.

[0064] The initial state at time t0 is a situation where the driver is gradually depressing the accelerator pedal 90 in the electric driving mode. At this time t0, the vehicle speed and the driver required torque are increasing, and the maximum torque of the motor generator 3 is decreasing due to a decrease in the state of charge of the battery 31 or the like. The torque difference value is increasing. The catalyst temperature and the second predetermined value are gradually decreasing. Also, the engine drive state is in the engine stop state, and the power transmission state is in the non-transmission state.

[0065] After that, at time t1, since the torque difference value becomes equal to or greater than a second predetermined value, the engine 2 is started. The engine driving state becomes a warm-up operation state. As a result, the decrease in the catalyst temperature stops, and the catalyst temperature rises after remaining constant for a short period of time. The period during which the catalyst temperature remains constant is also when the second predetermined value remains constant. Note that the reason the catalyst temperature remains constant after stopping its decrease is because the heat input to and output from the catalyst 2A are balanced. Depending on the situation such as the outside air temperature, the catalyst temperature and the second predetermined value may immediately change from a decrease to an increase.

[0066] After that, at time t2, the catalyst temperature rises to a predetermined temperature threshold (simply referred to as the threshold in the figure).

[0067] After that, at time t3, since the torque difference value becomes equal to or greater than a first predetermined value, the power transmission state is set to a transmission state. As a result, the driving force of the engine 2 is transmitted to the drive wheels 6. Also, the engine driving state is set to a state of using the drive source, and the operation of the engine 2 shifts from an operation for warming up the catalyst 2A to an operation for use as a drive source for traveling. In this way, at time t3, the vehicle shifts to hybrid driving.

[0068] Referring to FIG. 4, the transition of the vehicle state when the engine is stopped without shifting to hybrid driving after the execution of the catalyst warm-up operation will be described.

[0069] The initial state at time t10 is a situation where, in the electric driving mode as in FIG. 3, the driver is gradually depressing the accelerator pedal 90. At this time t10, the vehicle speed and the driver required torque are increasing, and the maximum torque of the motor generator 3 is decreasing due to a decrease in the state of charge of the battery 31 or the like. The torque difference value is increasing. The catalyst temperature, the second predetermined value, and the third predetermined value are gradually decreasing. Also, the engine driving state is an engine stopped state, and the power transmission state is a non-transmission state.

[0070] Thereafter, at time t11, since the torque difference value becomes equal to or greater than a second predetermined value, the engine 2 is started. The engine driving state enters the warm-up operation state. As a result, the decrease in the catalyst temperature stops, and the catalyst temperature changes in a constant manner. Since the catalyst temperature changes in a constant manner, the second predetermined value and the third predetermined value also change in a constant manner. Note that the reason why the catalyst temperature has stopped decreasing and then changes in a constant manner is that the heat input to and output from the catalyst 2A are balanced. Depending on the situation such as the outside air temperature, the catalyst temperature, the second predetermined value, and the third predetermined value may immediately change from a decrease to an increase.

[0071] Thereafter, at time t12, the driver required torque and the vehicle speed decrease, the maximum torque of the motor generator 3 increases, and the torque difference value decreases. Also, the catalyst temperature rises.

[0072] Thereafter, at time t13, since the torque difference value becomes less than the third predetermined value, the engine 2 is stopped.

[0073] As described above, in the present embodiment, the ECU 10 calculates, as the torque difference value, a value obtained by subtracting the maximum torque of the motor generator 3 that corresponds at least to the state of charge of the battery 31 from the driver required torque. Then, during the execution of the electric driving mode, when the torque difference value is equal to or greater than a first predetermined value, the ECU 10 switches to the hybrid driving mode. Also, during the execution of the electric driving mode, when the catalyst temperature of the catalyst 2A is equal to or lower than a predetermined temperature threshold value and the torque difference value is equal to or greater than a second predetermined value that is smaller than the first predetermined value, the ECU 10 starts the engine 2 to perform catalyst warm-up control for warming up the catalyst 2A.

[0074] Thereby, in a state where the catalyst temperature is equal to or lower than the temperature threshold value and the purification ability of the exhaust gas is not exhibited, the engine 2 can be started in advance to warm up the catalyst 2A before switching from the electric driving mode to the hybrid driving mode. Also, the warm-up of the catalyst 2A can be completed at the start of the hybrid driving.

[0075] As a result, even when shifting to hybrid driving as the driver-requested torque increases, it is possible to secure the warm-up time of the catalyst 2A and suppress deterioration of the exhaust gas performance.

[0076] Further, in the present embodiment, the second predetermined value is set so as to be smaller as the catalyst temperature is lower.

[0077] Thereby, the lower the catalyst temperature, the easier it is for the torque difference value to become equal to or greater than the second predetermined value, and the catalyst warm-up control is started at an earlier timing. For this reason, it is possible to surely secure the time required for warming up the catalyst 2A before switching to hybrid driving.

[0078] Further, in the present embodiment, when the torque difference value is less than a third predetermined value that is smaller than the second predetermined value during operation of the engine 2, the ECU 10 stops the engine 2. The third predetermined value is set so as to be smaller as the catalyst temperature is lower.

[0079] Thereby, when the torque difference value becomes less than the third predetermined value due to a decrease in the torque difference value or an increase in the catalyst temperature, the engine 2 can be stopped, so that deterioration of the exhaust gas performance can be suppressed.

[0080] Further, in the present embodiment, the ECU 10 calculates, as the torque difference value, a value obtained by subtracting the maximum torque of the motor generator 3 corresponding at least to the state of charge of the battery 31 from the driver-requested torque corresponding to a predetermined accelerator depression amount that is half or more of the maximum value.

[0081] Thereby, even when the actual accelerator depression amount is smaller than the predetermined accelerator depression amount, it is possible to determine whether or not to execute the catalyst warm-up control using the torque difference value based on the predetermined accelerator depression amount. For this reason, for example, when 80% of the accelerator depression amount is estimated as the predetermined accelerator depression amount, the catalyst warm-up control can be started at an earlier timing based on this estimated accelerator depression amount, so that the time required for warming up the catalyst 2A before switching to the hybrid driving mode can be secured.

[0082] Also, in this embodiment, the vehicle 1 is provided with a clutch 7 as a power transmission mechanism capable of setting the power transmission between the engine 2 and the drive wheels 6 to transmission or non - transmission. And, during the execution of the catalyst warm - up control, the ECU 10 sets the clutch 7 to non - transmission.

[0083] Thereby, by setting the clutch 7 to non - transmission during the execution of the catalyst warm - up control, the power of the engine 2 can be prevented from being used for running. Thus, the engine 2 can be operated in an optimal state for warming up the catalyst 2A while maintaining electric driving, and the deterioration of the exhaust gas performance can be suppressed.

[0084] Although embodiments of the present invention have been disclosed, it is obvious that those skilled in the art can make changes without departing from the scope of the present invention. It is intended that all such modifications and equivalents be included in the following claims.

Explanation of Reference Numerals

[0085] 1 Vehicle 2 Engine 2A Catalyst 3 Motor - generator (electric motor) 6 Drive wheels 7 Clutch (power transmission mechanism) 10 ECU (control unit) 31 Battery

Claims

1. An engine and an electric motor as drive sources, A catalyst for purifying exhaust gas of the engine, A vehicle control device for controlling a vehicle including a battery that exchanges power with the electric motor, comprising: A control unit that switches between an electric driving mode in which the engine operation is stopped and the vehicle runs on the power of the electric motor, and a hybrid driving mode in which the vehicle runs on the power of the engine and the power of the electric motor; A power transmission mechanism capable of setting power transmission between the engine and the drive wheels to transmission or non - transmission; The control unit calculates, as a torque difference value, a value obtained by subtracting the maximum torque of the electric motor corresponding at least to the state of charge of the battery from the driver - required torque, During the execution of the electric driving mode, when the torque difference value is equal to or greater than a first predetermined value, the control unit switches to the hybrid driving mode; During the execution of the electric driving mode, when the catalyst temperature of the catalyst is equal to or lower than a predetermined temperature threshold and the torque difference value is equal to or greater than a second predetermined value smaller than the first predetermined value, the control unit starts the engine to perform catalyst warm - up control for warming up the catalyst. During the execution of the catalyst warm - up control, the power transmission mechanism is set to non - transmission. A vehicle control device characterized by this.

2. The second predetermined value is set such that it becomes smaller as the catalyst temperature is lower. The vehicle control device according to claim 1.

3. During the operation of the engine, when the torque difference value is less than a third predetermined value smaller than the second predetermined value, the control unit stops the engine. The third predetermined value is set such that it becomes smaller as the catalyst temperature is lower. The vehicle control device according to claim 1 or claim 2.

4. The control unit calculates, as the torque difference value, a value obtained by subtracting, from the driver required torque corresponding to a predetermined accelerator depression amount that is equal to or more than half of the maximum value, the maximum torque of the electric motor that at least corresponds to the state of charge of the battery, according to the vehicle control device according to any one of claims 1 to 3.

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