Hybrid vehicle control method and hybrid vehicle control system

Abstract

A method for controlling a hybrid vehicle in which power is supplied and received between a drive motor (1) and a battery (2), the battery (2) is charged by a generator (4) driven by an engine (3) for power generation, and exhaust gas discharged from the engine (3) is treated by a catalyst. When the charging rate of the battery (2) exceeds a predetermined threshold value due to regenerative power received from the drive motor (1), fuel supply to the engine (3) is stopped, power generation by the generator (4) is stopped, fuel supply to the engine (3) is stopped, power is supplied from the battery (2) to the generator (4), and the engine (3) is powered (motor operation), thereby consuming regenerative power. In a state where the temperature of the catalyst is lower than an upper limit temperature at which deterioration of the catalyst can be suppressed, the discharge amount of the battery (2) is increased as the temperature of the catalyst approaches the upper limit temperature or as the rate of increase of the temperature of the catalyst increases.

Description

Technical Field

[0001] The invention relates to a control method of a hybrid vehicle and a control system of a hybrid vehicle. Background Art

[0002] JP2021-110268A discloses that the electric motor has: a generator that generates electricity by being driven by an engine for generating electricity; a catalyst that processes exhaust gas discharged from the engine; a battery that stores electricity generated by the generator and supplies electricity to the motor; and a battery control unit that prohibits the generator from generating electricity when the battery charge rate is greater than or equal to a first charge rate threshold for suppressing overcharging. In addition, in JP2021-110268A, regarding the battery control unit, when a discharge condition that the battery charge rate exceeds a second charge rate threshold lower than the first charge rate threshold is satisfied, the power supplied from the battery to the motor is increased compared to a case where the discharge condition is not satisfied. Summary of the invention

[0003] However, even if regenerative power is received from the motor, the charge rate of the battery increases. Furthermore, a situation may occur in which the battery receives regenerative power from the motor for a long time and reaches the first charge rate threshold. In this case, in order to suppress overcharging as described above, the following control is required, namely, stopping the fuel supply to the engine and supplying the battery power to the generator to drive the engine (internal combustion engine) (power running operation), that is, discharging by running the motor to consume the regenerative power. On the other hand, if the catalyst is exposed to a lean atmosphere in a state exceeding the specified upper limit temperature, it will deteriorate. Therefore, if the fuel supply to the engine is stopped in a state in which the temperature of the catalyst exceeds the upper limit temperature, the catalyst may deteriorate.

[0004] Therefore, an object of the present invention is to provide a control method for a hybrid vehicle and a control system for a hybrid vehicle that suppress degradation of a catalyst.

[0005] According to a certain embodiment of the present invention, in a control method for a hybrid vehicle, power is supplied and received between a drive motor and a battery, a generator driven by an engine for power generation charges the battery, and a catalyst is used to treat exhaust gas discharged from the engine. In this control method, if the charge rate of the battery exceeds a predetermined threshold value due to the regenerative power received from the drive motor, the fuel supply to the engine is stopped to stop the power generation of the generator, and power is supplied from the battery to the generator to cause the engine to operate under power, thereby consuming the regenerative power. Moreover, in a state where the temperature of the catalyst is lower than the upper limit temperature that can suppress the degradation of the catalyst, the closer the temperature of the catalyst is to the upper limit temperature, or the faster the temperature of the catalyst increases, the more the discharge amount of the battery increases. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a schematic diagram of a control system of a hybrid vehicle according to the present embodiment.

[0007] Figure 2 The graph is a charge / discharge request curve showing a charge request to a battery and a discharge request to a battery in a coordinate space having a charge / discharge current to a battery and a charge rate of the battery as axes.

[0008] Figure 3 This is a correspondence diagram showing the relationship between the temperature of the catalyst, the rate of increase in the temperature of the catalyst, and the center charging rate set by the vehicle controller.

[0009] Figure 4 It is a timing diagram of the temperature of the catalyst, the discharge request output by the vehicle controller, and the center charging rate set by the vehicle controller.

[0010] Figure 5 is a block diagram of the vehicle controller.

[0011] Figure 6 It is a correspondence map of the request adjustment unit constituting the vehicle controller, and is a correspondence map for calculating the center charging rate (Z) of the battery based on the first center charging rate (Y) calculated by the charging request unit and the second center charging rate (X) calculated by the discharging request unit.

[0012] Figure 7 It is the control flow chart of the vehicle controller. DETAILED DESCRIPTION

[0013] [Basic structure of this embodiment]

[0014] Figure 1 FIG. 2 is a schematic diagram of a control system of a hybrid vehicle according to the present embodiment. Figure 1 As shown, the control system of the hybrid vehicle of the present embodiment is composed of a drive motor 1, a battery 2, an engine 3, a generator 4, a catalyst system 5, and a control unit (a vehicle controller 7, an engine controller 8, and a motor controller 9).

[0015] The drive motor 1 is mechanically coupled to the drive wheels 12 via the speed reducer 10 and the drive shaft 11, and receives power from the battery 2 (and the generator 4) to drive the drive wheels 12. The drive motor 1 generates regenerative power when reducing the rotation of the drive wheels 12.

[0016] The battery 2 supplies electric power to the drive motor 1 , and is charged with regenerative electric power generated by the drive motor 1 and electric power generated by the generator 4 .

[0017] The engine 3 (internal combustion engine) is, for example, a gasoline engine. The engine 3 is coupled to the generator 4 in a power-transmitting manner, and the engine 3 burns fuel (gasoline) to rotate the generator 4, thereby causing the generator 4 to generate electricity.

[0018] The generator 4 supplies the generated power to the battery 2 and the drive motor 1. In addition, the generator 4 sometimes receives power from the battery 2 to make the engine 3, which stops the fuel supply, perform power running (motor operation). In addition to the purpose of consuming excess regenerative power, this power running is also used to crank the engine 3 when the engine 3 is started, or to generate negative pressure for brake pedal assistance.

[0019] The catalyst system 5 processes the exhaust gas exhausted from the engine 3 so as to convert it into harmless gas, and releases the harmless gas to the outside through the muffler 6 .

[0020] The control unit (vehicle controller 7, engine controller 8, motor controller 9) is composed of one or more microcomputers having a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). Regarding the control unit (vehicle controller 7, engine controller 8, motor controller 9), the CPU executes the program stored in the ROM or RAM to perform various controls.

[0021] The vehicle controller 7 outputs a torque command value to the motor controller 9 based on the accelerator opening indicated by the accelerator pedal 13 .

[0022] When the charging rate of the battery 2 is higher than the prescribed reference charging rate (center charging rate), the vehicle controller 7 outputs a discharge request to the motor controller 9. Conversely, when the charging rate of the battery 2 is lower than the prescribed reference charging rate, the vehicle controller 7 outputs a charging request to the motor controller 9.

[0023] Furthermore, when the catalyst degradation suppression control described later is executed, the vehicle controller 7 shifts the central charging rate to a lower charging rate side compared to the reference charging rate (e.g., 55[%]), and when the advance charging request control described later is executed, the central charging rate shifts to a higher charging rate side compared to the reference charging rate. Furthermore, when it is determined that the catalyst degradation suppression control described later and the advance charging request control described later are both required, the vehicle controller 7 sets the central charging rate to a charging rate coordinated between the two controls as described later.

[0024] Furthermore, when the charging rate of the battery 2 exceeds a predetermined threshold value (eg, 80% ), the vehicle controller 7 outputs an engine stop command to the engine controller 8 and outputs a power running operation command to the motor controller 9 .

[0025] If the engine start command is received from the vehicle controller 7, the engine controller 8 starts supplying fuel to the engine 3 and starts the engine 3. The engine controller 8 controls the output of the engine 3 based on the output requested from the generator 4, and controls the output of the engine 3 in such a way that the operating point (rotation speed, torque) of the engine 3 becomes the optimal operating point (the point with the highest output efficiency).

[0026] Furthermore, upon receiving an engine stop command from the vehicle controller 7 , the engine controller 8 stops the supply of fuel to the engine 3 and stops the driving of the engine 3 (the power generation of the generator 4 ).

[0027] Furthermore, the engine controller 8 acquires information on the temperature of a catalyst (eg, titanium (Ti)) included in the catalyst system 5 and outputs it to the vehicle controller 7 .

[0028] The motor controller 9 controls the drive motor 1 based on the torque command value and the discharge request (or the charge request), and controls the generator 4 based on the discharge request (or the charge request).

[0029] When a discharge request is input from the vehicle controller 7 , the motor controller 9 increases the amount of discharge from the battery 2 and correspondingly reduces the output of the generator 4 .

[0030] Furthermore, when a charging request is input from the vehicle controller 7 , the motor controller 9 reduces the amount of discharge from the battery 2 and increases the output of the generator 4 accordingly.

[0031] Then, upon receiving a power running operation command from the vehicle controller 7 , the motor controller 9 drives the generator 4 using the power (discharge) from the battery 2 , thereby causing the engine 3 , to which fuel supply is stopped, to perform power running operation (motor operation).

[0032] The motor controller 9 includes a first inverter that connects the battery 2 and the drive motor 1 and a second inverter that connects the generator 4 and the battery 2 (and the drive motor 1 ). The inverters described above may be different from the motor controller 9 in structure.

[0033] The first inverter converts the DC power of the battery 2 into AC power based on the torque command value and the discharge request (or the charge request) and outputs it to the drive motor 1. When the motor controller 9 receives the discharge request, the first inverter outputs AC power greater than the AC power obtained according to the torque command value to the drive motor 1. When the motor controller 9 receives the charge request, the first inverter outputs AC power less than the AC power obtained according to the torque command value to the drive motor 1. In addition, when the drive motor 1 generates regenerative power, the first inverter converts it into DC power and charges the battery 2.

[0034] The second inverter converts the AC power generated by the generator 4 into DC power to charge the battery 2. When the motor controller 9 receives a power running command, the second inverter converts the DC power of the battery 2 and outputs it to the generator 4.

[0035] [Charge and discharge request curve]

[0036] Figure 2 The graph is a charge / discharge request curve showing a charge request to the battery 2 and a discharge request to the battery 2 in a coordinate space having the charge / discharge current to the battery 2 and the charge rate of the battery 2 as axes.

[0037] like Figure 2 As shown, the charge and discharge request curve has an inflection point with respect to a predetermined center charge rate (reference charge rate), and a monotonically increasing curve is drawn in a shape that is more convex upward when the charge rate is lower than the center charge rate, and a monotonically decreasing curve is drawn in a shape that is more convex downward when the charge rate is higher than the center charge rate. On the charge and discharge request curve, the charge request is zero when the charge rate is greater than or equal to the center charge rate, and the discharge request is zero when the charge rate is less than or equal to the center charge rate. That is, when the charge rate is the center charge rate, the charge request and the discharge request are zero.

[0038] The lower the charging rate is than the center charging rate, the more the charging request amount (current value) of the charging request increases monotonically according to the charging and discharging request curve.

[0039] As the charging rate is higher than the center charging rate, the discharge request amount (current value) of the discharge request increases monotonically according to the charge and discharge request curve.

[0040] The vehicle controller 7 sets the charge and discharge request curve so that the initial value of the center charge rate becomes a reference charge rate (for example, 55[%]).

[0041] On the other hand, when the vehicle controller 7 performs the catalyst degradation suppression control described later, the center charging rate is shifted toward, for example, a lower charging rate side compared to the reference charging rate, thereby shifting the charge and discharge request curve toward the lower charging rate side. In addition, when the vehicle controller 7 performs the advance charge request control described later, the center charging rate is shifted toward, for example, a higher charging rate side compared to the reference charging rate, thereby shifting the charge and discharge request curve toward the higher charging rate side. Furthermore, when it is determined that the catalyst degradation suppression control described later and the advance charge request control are both required, the vehicle controller 7 sets the center charging rate to be coordinated between the two controls as described later.

[0042] [Catalyst degradation suppression control and advance charge request control]

[0043] Figure 3The correspondence diagram shows the relationship between the temperature of the catalyst, the rate of increase of the temperature of the catalyst, and the center charging rate set by the vehicle controller 7 .

[0044] The charge rate of the battery 2 increases due to the regenerative power received from the drive motor 1 and the generated power received from the generator 4. In particular, if the regenerative power is received for a long time and exceeds a predetermined threshold value (e.g., 80 [%]), the battery 2 becomes overcharged and may deteriorate. Therefore, in the present embodiment, if the threshold value is exceeded, the following control is also performed, that is, the fuel supply to the engine 3 is stopped to stop the power generation of the generator 4, and the engine 3 with the fuel stopped is powered (motor operation) to consume the regenerative power (reducing the charge rate of the battery 2). At this time, the catalyst is exposed to a rarefied atmosphere, but if the temperature of the catalyst at this time exceeds a predetermined upper limit temperature (e.g., 700° C.), the catalyst may be degraded.

[0045] Therefore, in the present embodiment, the following catalyst degradation suppression control is performed, that is, the frequency of the charge rate of the battery 2 exceeding the threshold value (e.g., 80[%]) for executing the motor operation of the engine 3 is reduced in a state where the temperature of the catalyst exceeds the upper limit temperature (e.g., 700[°C]), thereby suppressing the degradation of the catalyst. In the catalyst degradation suppression control, the center charge rate of the battery 2 is shifted to the low charge rate side, and the frequency of the charge rate of the battery 2 exceeding the threshold value is reduced, thereby suppressing the degradation of the catalyst.

[0046] In the catalyst degradation suppression control, when the temperature of the catalyst exceeds the first reference temperature (for example, 650°C) which is lower than the upper limit temperature (700°C), the center charging rate is set to a charging rate lower than the reference charging rate. The higher the temperature of the catalyst, the more the center charging rate is shifted toward the low charging rate side.

[0047] In addition, in the catalyst degradation suppression control, even when the temperature of the catalyst is lower than the upper limit temperature, if the temperature increase rate exceeds the specified rate, the center charging rate is set to a charging rate lower than the reference charging rate. The faster the increase rate, the more the center charging rate is shifted toward the low charging rate side.

[0048] Therefore, in a coordinate space where the horizontal axis is the temperature of the catalyst and the vertical axis is the rate of increase in the temperature of the catalyst, it is possible to use Figure 3 The isocenter charging rate line shown indicates the center charging rate set in the catalyst degradation suppression control. Figure 3 In the same isocenter charging rate line, the same center charging rate is present. In addition, the farther the isocenter charging rate line is from the origin, the lower the center charging rate is.

[0049] Figure 3The shown isocenter charging rate line can also be applied to the case where the temperature of the catalyst is lower than the first reference temperature. However, except for the case where the prior charging request control described later is simultaneously executed, when the center charging rate requested in the catalyst degradation suppression control is higher than the reference charging rate, the catalyst degradation suppression control is not substantially executed.

[0050] In addition, when the same center charging rate is applied, the trigger level when the catalyst temperature rises (the temperature when switching to the center charging rate) is made higher than the trigger level when the temperature drops (the temperature when switching to the center charging rate), so that a hysteresis width (for example, 20 [°C]) is preferably set with respect to the temperature. Thus, when the catalyst temperature repeatedly rises and falls, the center charging rate can be set not to be switched at a high frequency, and the burden of control can be reduced.

[0051] Furthermore, in the catalyst degradation suppression control, the output of the generator 4 (the output of the engine 3 ) can be limited so that the temperature of the catalyst does not exceed the upper limit temperature.

[0052] Figure 4 It is a timing diagram of the catalyst temperature, the discharge request output by the vehicle controller 7, and the center charge rate set by the vehicle controller 7. Before time t0, the engine 3 is started and the generator 4 generates electricity, and exhaust gas is discharged to the catalyst system 5, thereby increasing the catalyst temperature (BED temperature). In addition, the center charge rate is set to the reference charge amount.

[0053] If the catalyst temperature reaches the first reference temperature (T c1 ) (e.g. 650°C), the vehicle controller 7 makes the central charging rate according to Figure 3 The corresponding diagram is lowered, thereby outputting a discharge request to the motor controller 9.

[0054] The motor controller 9 increases the electric power (discharge amount) from the battery 2 to the drive motor 1 and reduces the output of the generator 4 .

[0055] As the temperature of the catalyst increases, the vehicle controller 7 shifts the central charge rate toward the lower charge rate side. Therefore, as the central charge rate decreases, the power supplied from the battery 2 to the drive motor 1 increases, and the output of the generator 4 decreases accordingly.

[0056] When the temperature of the catalyst reaches a peak value (e.g., 670°C) at time t2, the center charging rate is also set to the lowest state. This can reduce the frequency of the charging rate of the battery 2 exceeding the threshold value (e.g., 80%). If the temperature of the catalyst decreases after time t2, the vehicle controller 7 starts to gradually restore the center charging rate to its original state.

[0057] At time t3, the temperature of the catalyst reaches, for example, a second reference temperature (T c2 ) (e.g. 630°C), the center charging rate reaches the original reference charging amount, but the vehicle controller 7 sets the center charging rate to the reference charging amount and stops the discharge request. This control prevents the catalyst temperature from exceeding the upper limit temperature (T max )(for example 700[℃]).

[0058] In addition, in the catalyst degradation suppression control, it is preferable to further perform the following control, that is, without changing the output of the generator 4, the discharge amount of the battery 2 is increased. In this case, the frequency of the charging rate of the battery 2 exceeding the threshold value (e.g., 80%]) is reduced, so the frequency of stopping the fuel supply to the engine 3 and executing the motor operation of the engine 3 when the temperature of the catalyst exceeds the upper limit temperature can be reduced, and the degradation of the catalyst can be suppressed.

[0059] [Vehicle Controller 7]

[0060] Figure 5 7 is a block diagram of the vehicle controller 7. Here, it is a block diagram when the vehicle controller 7 performs the above-mentioned catalyst degradation suppression control and advance charge request control. The vehicle controller 7 includes a charge request unit 701, a discharge request unit 702, and a request adjustment unit 703.

[0061] The charging request unit 701 is a structural element that performs advance charging request control. Map information is input to the charging request unit 701. The map information is the terrain (altitude and slope of the road surface) and traffic conditions (the presence or absence of expressways, etc.) of the driving route to the destination of the vehicle, for example, from the current driving position of the vehicle to the driving route of a predetermined distance (for example, 5 [km] or 10 [km]), and gives a hint of the future driving state of the vehicle.

[0062] Regarding the charging request unit 701, with reference to the map information, for example, when the vehicle is currently traveling on flat ground but an uphill road with a specified slope begins after 2 kilometers and continues for a distance greater than or equal to a specified distance, it is determined that high-load operation is being performed that consumes the power of the battery 2 compared to normal operation. Here, normal operation refers to, for example, a state in which the vehicle is traveling at a normal speed (for example, 60 [km / s]) on a general road on flat ground. In addition, high-load operation refers to a state in which the power supply from the generator 4 to the drive motor 1 is made substantially constant and the power supply from the battery 2 to the drive motor 1 is significantly increased to cause the vehicle to travel.

[0063] The charging request unit 701 calculates the amount of work required until the vehicle reaches the detected uphill slope, calculates the first central charging rate (e.g., the minimum charging rate that can be allowed in principle by the prior charging request control) based on the work as the charge amount of the battery 2 that can supply the work, and outputs it to the request adjustment unit 703. As a result, the output of the generator 4 does not need to be increased during high-load operation, so the acoustic and vibration performance of the vehicle can be improved.

[0064] In addition, for example, when it is determined that the vehicle is currently traveling on a general road but enters a highway after 2 kilometers and performs high-speed operation (high-load operation), the charging request unit 701 also calculates the amount of work used for high-speed operation, and based on the work, calculates the first center charging rate as the charge amount of battery 2 that can supply the work, and outputs it to the request adjustment unit 703.

[0065] In addition, the road slope, altitude, and vehicle speed may be input to the charge request unit 701, and the first center charge rate may be corrected based on the above information. The charge request unit 701 may be corrected so that the first center charge rate increases with the steeper the slope, the faster the vehicle speed, and the higher the altitude.

[0066] The discharge request unit 702 is a component that performs the catalyst degradation suppression control. When the catalyst temperature is input to the discharge request unit 702, the catalyst temperature rise rate is calculated. Figure 3 The map shown calculates the second central charging rate (for example, the maximum charging rate that is allowable in principle in the catalyst degradation suppression control) and outputs it to the request adjustment unit 703 .

[0067] In addition, the map information is input to the discharge request unit 702. It is expected that, for example, the temperature of the catalyst reaches the first reference temperature after 2 kilometers of the vehicle, and a downhill road with a specified slope begins to appear after the 2 kilometers. If it is expected that the downhill road will continue for a distance greater than or equal to the specified distance, the second center charging rate can be set to a lower value.

[0068] The request adjustment unit 703 compares the reference charging rate, the first center charging rate output from the charge request unit 701, and the second center charging rate output from the discharge request unit 702 in the manner described below, and calculates a final center charging rate.

[0069] [Corresponding diagram of request adjustment unit 703]

[0070] Figure 6It is a correspondence diagram possessed by the request adjustment unit 703 constituting the vehicle controller 7, and is a correspondence diagram in which the vehicle controller 7 calculates the center charging rate (Z) serving as a basis for judging the discharge request and the request based on the first center charging rate (Y) calculated by the charging request unit 701 and the second center charging rate (X) calculated by the discharge request unit 702.

[0071] Figure 6 The vertical axis is the first center charging rate (Y), which is equivalent to the lower limit value of the charging rate of the battery 2 requested by the charging request unit 701. Figure 7 The horizontal axis is the second central charging rate (X), which corresponds to the upper limit value of the charging rate of the battery 2 requested by the discharge request unit 702. The reference charging rate is set to, for example, X=X1, Y=Y1 (X1=Y1=55[%]).

[0072] When the first center charging rate (Y) and the second center charging rate (X) are consistent (with Figure 6 In the case where the line of Y=X shown in FIG. 1 overlaps), the adjustment unit 703 is requested to set the center charging rate (Z) to the first center charging rate (Y) or the second center charging rate (X).

[0073] More specifically, when the first center charging rate (Y) and the second center charging rate (X) are the same value and higher than the reference charging rate, the request adjustment unit 703 sets the center charging rate (Z) based on the request from the charging request unit 701, not the request from the discharging request unit 702. In addition, when the first center charging rate (Y) and the second center charging rate (X) are the same value and lower than the reference charging rate, the request adjustment unit 703 sets the center charging rate (Z) based on the request from the discharging request unit 702, not the request from the charging request unit 701. And, when the first center charging rate (Y) and the second center charging rate (X) are consistent with the reference charging rate, the request adjustment unit 703 sets the center charging rate (Z) to the reference charging rate, not the request from the charging request unit 701 and the request from the discharging request unit 702.

[0074] When the first center charging rate (Y) is lower than the second center charging rate (X), and when the first center charging rate (Y) is lower than the reference charging rate and the second center charging rate (X) is higher than the reference charging rate ( Figure 6 A area), the adjustment unit 703 is requested to set the central charging rate (Z) as the reference charging rate, that is, to set it to Z=X1=Y1.

[0075] In this case, the reference charging rate is higher than the first central charging rate (Y) requested by the charging request unit 701 and lower than the second central charging rate (X) requested by the discharge request unit 702, and the reference charging rate satisfies the charging rates requested by both. Therefore, the request adjustment unit 703 sets the central charging rate to the reference charging rate.

[0076] When the first center charging rate (Y) is lower than the second center charging rate (X), and when the first center charging rate (Y) and the second center charging rate (X) are higher than the reference charging rate ( Figure 6 B area), the request adjustment unit 703 sets the center charging rate (Z) to the first center charging rate (Y), that is, sets Z = Y. In this case, the catalyst degradation request control is not actually performed, so the request adjustment unit 703 sets the center charging rate (Z) to the first center charging rate (Y).

[0077] When the first center charging rate (Y) is lower than the second center charging rate (X), and when the first center charging rate (Y) and the second center charging rate (X) are lower than the reference charging rate ( Figure 6 The request adjustment unit 703 sets the center charging rate (Z) to the second center charging rate (X), that is, Z = X. In this case, the prior charging request control is not actually performed, so the request adjustment unit 703 sets the center charging rate (Z) to the second center charging rate (X).

[0078] When the first center charging rate (Y) is higher than the second center charging rate (X), and when the first center charging rate (Y) is lower than the predetermined lower limit value (Y min , for example, 46[%]) Figure 6 D area), the request adjustment unit 703 sets the center charging rate (Z) to the second center charging rate (X), that is, sets Z = Y. In the case where the first center charging rate (Y) requested by the charge request unit 701 is higher than the second center charging rate (X) requested by the discharge request unit 702, it is more complicated to determine which one is preferred. However, when the first dielectric constant (Y) is lower than the specified lower limit (Y min ), it can also be determined that the prior charging request control is not actually performed. At this time, the second center charging rate (X) also becomes a value lower than the prescribed charging rate (X <X2=Y min ), a stronger discharge request is issued as a catalyst degradation request control. Therefore, as a stronger discharge request issued from the discharge request unit 702, the request adjustment unit 703 sets the center charging rate (Z) to the first center charging rate (Y).

[0079] When the first center charging rate (Y) is higher than the second center charging rate (X), and when the first center charging rate (Y) is higher than the value ratio lower limit (Y min ) higher specified upper limit value (Y max , for example, in the case of 69[%]) ( Figure 6 E area), requesting the adjustment unit 703 to set the center charging rate (Z) to the first center charging rate (Y), that is, to set Z=Y.

[0080] In this case, the request adjustment unit 703 executes a stronger charge request as the advance charge request control, determines that the control should be executed preferentially over the catalyst degradation suppression control, and sets the center charge rate (Z) to the first center charge rate (Y).

[0081] When the first center charging rate (Y) is higher than the second center charging rate (X), and when the first center charging rate (Y) is the lower limit value (Y min ) and the upper limit value (Y max ) and the second center charging rate (X) is lower than X2 = Ymin ( Figure 6 The closer the first center charging rate (Y) is to the upper limit value (Y max ), the adjustment unit 703 is requested to set the central charging rate (Z) to a value closer to the first central charging rate (Y), and the first central charging rate (Y) is closer to the lower limit value (Y). min ), the adjustment unit 703 is requested to set the center charging rate (Z) to a value closer to the second center charging rate (X). Here, the relationship Y=X( Figure 6 ), X2 is the value of X obtained by substituting Ymin for Y, and is the same value as Ymin.

[0082] In this case, the center charging rate (Z) can be calculated using the first center charging rate (Y), the second center charging rate (X), the lower limit (Y min )、Upper limit value(Y max ) and is expressed by the following formula (1).

[0083] [Mathematical formula 1]

[0084]

[0085] In the above case, the request adjustment unit 703 does not perform control that gives priority to only one of the pre-charge request control and the catalyst degradation control, but coordinates between the first center charging rate (Y) and the second center charging rate (X), and sets a center charging rate (Z) that is not disadvantageous to either the pre-charge request control or the catalyst degradation control, thereby achieving a balance between the pre-charge request control and the catalyst degradation control.

[0086] When the first center charging rate (Y) is higher than the second center charging rate (X), and when the first center charging rate (Y) is the lower limit value (Y min ) and the upper limit value (Y max ) and the second center charging rate (X) is greater than or equal to X2 = Ymin and less than X3 = Ymax ( Figure 6 G area), the adjustment unit 703 is requested to set the center charging rate (Z) to the first center charging rate (Y), that is, to set Z = Y. Here, the relationship Y = X ( Figure 6 ), X3 is the value of X obtained by substituting Ymax for Y, and is the same value as Ymax.

[0087] In this case, the request adjustment unit 703 performs a strong charge request as the advance charge request control, determines that the control should be executed with priority over the catalyst degradation suppression control, and sets the center charge rate (Z) to the first center charge rate (Y).

[0088] [Control flow of vehicle controller 7]

[0089] Figure 7 7 is a control flow chart of the vehicle controller 7. In step S1, the vehicle controller 7 (discharge request unit 702) obtains information on the temperature of the catalyst (BED temperature). In addition, the vehicle controller 7 (charge request unit 701) obtains map information related to the driving route that the vehicle is about to pass through, with respect to information on the driving route to the destination of the vehicle.

[0090] In step S2, the vehicle controller 7 (discharge request unit 702) calculates the catalyst temperature increase rate based on the catalyst temperature obtained last time and the catalyst temperature obtained this time, and calculates the catalyst temperature increase rate based on the information of the temperature obtained this time, the calculated catalyst temperature increase rate and the catalyst temperature. Figure 3 The second center charging rate is calculated based on the corresponding diagram shown.

[0091] In step S3 , the vehicle controller 7 (charging request unit 701 ) calculates the amount of work (consumed energy) of the vehicle based on the map information.

[0092] In step S4 , the vehicle controller 7 (charging request unit 701 ) calculates a first central charging rate based on the amount of work.

[0093] In step S5, the vehicle controller 7 (charge request unit 701) Figure 6 In the correspondence diagram shown, the center charging rate is calculated with reference to the first center charging rate and the second center charging rate.

[0094] When the charge rate of the battery 2 is higher than the calculated center charge rate, the vehicle controller 7 outputs a discharge request to the motor controller 9 . Conversely, when the charge rate of the battery 2 is lower than the calculated center charge rate, the vehicle controller 7 outputs a charge request to the motor controller 9 .

[0095] [Effects of this embodiment]

[0096] According to the control method of the hybrid vehicle of the present embodiment, power is supplied and received between the drive motor 1 and the battery 2, the generator 4 driven by the engine 3 for power generation charges the battery 2, and the exhaust gas discharged from the engine 3 is treated by the catalyst (catalyst system 5), wherein, if the charging rate of the battery 2 exceeds a predetermined threshold value (e.g., 80[%]) due to the regenerative power received from the drive motor 1, the fuel supply to the engine 3 is stopped to stop the power generation of the generator 4, and the power is supplied from the battery 2 to the generator 4 to drive the engine 3 to consume the regenerative power, and in a state where the temperature of the catalyst (the catalyst included in the catalyst system 5) is lower than the upper limit temperature (e.g., 700[°C]) that can suppress the deterioration of the catalyst, the closer the temperature of the catalyst (the catalyst included in the catalyst system 5) is to the upper limit temperature (e.g., 700[°C]) or the faster the temperature increase rate of the catalyst (the catalyst included in the catalyst system 5) is, the more the discharge amount of the battery 2 increases.

[0097] According to the above method, the frequency of executing the power running operation (motor operation) of the engine 3 when the temperature of the catalyst exceeds the upper limit temperature (e.g., 700 [° C.]) can be reduced, thereby suppressing the degradation of the catalyst. In addition, since the degradation of the catalyst can be suppressed, the amount of the catalyst (precious metal) can be reduced.

[0098] In the present embodiment, in a coordinate space having the charge and discharge current and the charge rate for the battery 2 as axes, a charge and discharge request curve ( Figure 2), when the charging rate is controlled, as a discharge amount increase control (catalyst degradation suppression control) for increasing the discharge amount of battery 2, the center charging rate is shifted to a lower charging rate side compared to the reference charging rate, thereby shifting the charge and discharge request curve to the lower charging rate side.

[0099] According to the above method, it is possible to make a discharge request by reducing the center charge rate in a simple manner.

[0100] In the present embodiment, map information related to the previous driving route that the vehicle is about to pass is obtained from the information on the driving route to the destination of the vehicle. When it is predicted with reference to the map information that the vehicle is performing high-load operation that consumes more electric power of the battery 2 than normal operation, the advance charging request control that shifts the center charging rate to the high charging rate side is executed. When it is determined based on the map information that the vehicle is traveling uphill for a distance greater than or equal to a specified distance, the advance charging request control is prioritized. When it is determined based on the map information that the vehicle is traveling downhill for a distance greater than or equal to a specified distance, the discharge amount increase control (catalyst degradation suppression control) is prioritized.

[0101] According to the above method, it is possible to selectively execute the advance charging request control and the discharge amount increase control (catalyst degradation suppression control) according to the condition of the road on which the vehicle is traveling.

[0102] In the present embodiment, map information related to the driving route that the vehicle is about to pass is obtained from the information on the driving route to the destination of the vehicle. When the advance charge request control that shifts the center charge rate (Z) to the high charge rate side is executed in a case where it is predicted with reference to the map information that the vehicle will perform a high-load operation that consumes more power of the battery 2 than in the normal operation, the amount of work done in the high-load operation is calculated based on the map information, and the center charge rate requested by the advance charge request control is calculated as the first center charge rate (Y) based on the amount of work done, and the center charge rate requested by the discharge amount increase control (catalyst degradation suppression control) is calculated as the second center charge rate (X) based on the temperature or the rise rate of the catalyst. In a case where the first center charge rate (Y) is higher than the second center charge rate (X) and the first center charge rate (Y) is lower than a prescribed lower limit value (Y), the control is performed. min ), the center charging rate (Z) is set to the second center charging rate (X), and when the first center charging rate (Y) is higher than the second center charging rate (X), and the first center charging rate (Y) is higher than the value ratio lower limit (Y min ) higher specified upper limit value (Y max), the center charging rate (Z) is set to the first center charging rate (Y), and when the first center charging rate (Y) is higher than the second center charging rate (X) and the first center charging rate (Y) is the lower limit value (Y min ) and the upper limit value (Y max ), the closer the first center charging rate (Y) is to the upper limit value (Y max ), the center charging rate (Z) is set to a value closer to the first center charging rate (Y), and the first center charging rate (Y) is closer to the lower limit value (Y). min ), the center charging rate (Z) is set to a value closer to the second center charging rate (X).

[0103] According to the above method, in the pre-charge request control, the higher the first center charge rate (Y), the higher the priority, and in the catalyst degradation request control, the lower the second center charge rate (X), the higher the priority. Therefore, the priority of the pre-charge request control and the catalyst degradation suppression control can be judged according to the condition of the road on which the vehicle is traveling, and the pre-charge request control and the catalyst degradation suppression control can be appropriately executed. In addition, when executing the catalyst degradation suppression control, the charge rate of the battery 2 is reduced in advance, so that the number of times the motor of the engine 3 is operated when the temperature of the catalyst is less than or equal to the upper limit temperature can be reduced.

[0104] In the present embodiment, when the first center charging rate (Y) and the second center charging rate (X) are the same, the center charging rate (Z) is set to the first center charging rate (Y) or the second center charging rate (X); when the first center charging rate (Y) is lower than the second center charging rate (X), and when the first center charging rate (Y) is lower than the reference charging rate (Y1, for example, 55[%]) and the second center charging rate (X) is higher than the reference charging rate (X1=Y1), the center charging rate (Z) is set to the reference charging rate. Charging rate: when the first center charging rate (Y) is lower than the second center charging rate (X), and the first center charging rate (Y) and the second center charging rate (X) are higher than the reference charging rate, the center charging rate (Z) is set to the first center charging rate (Y); when the first center charging rate (Y) is lower than the second center charging rate (X), and the first center charging rate (Y) and the second center charging rate (X) are lower than the reference charging rate, the center charging rate (Z) is set to the second center charging rate (X).

[0105] According to the above method, in the pre-charge request control, the higher the first center charge rate (Y), the higher the priority, and in the catalyst degradation request control, the lower the second center charge rate (X), the higher the priority. Therefore, the priority of the pre-charge request control and the catalyst degradation suppression control can be judged according to the condition of the road on which the vehicle is traveling, and the pre-charge request control and the catalyst degradation suppression control can be appropriately executed. In addition, when executing the catalyst degradation suppression control, the charge rate of the battery 2 is reduced in advance, so that the number of times the motor of the engine 3 is operated when the temperature of the catalyst is less than or equal to the upper limit temperature can be reduced.

[0106] In the present embodiment, the output of the engine 3 driving the generator 4 is reduced by the amount of increase in the discharge amount of the battery 2 .

[0107] According to the above method, the output of the engine 3 driving the generator 4 is reduced to suppress the increase in the temperature of the catalyst, thereby suppressing the degradation of the catalyst.

[0108] The control system of the hybrid vehicle according to the present embodiment includes: a drive motor 1; a battery 2 that supplies and receives electric power to and from the drive motor 1; a generator 4 that generates electric power and charges the battery 2 by being driven by an engine 3 for power generation; a catalyst (catalyst system 5) that processes exhaust gas discharged from the engine 3; and a control unit (a vehicle controller 7, an engine controller 8, a motor controller 9) that controls the battery 2, the engine 3, and the generator 4. If the charging rate of the battery 2 exceeds a predetermined threshold value (e.g., 80% %) due to the regenerative power received from the drive motor 1, the control unit (the vehicle controller 7, the engine controller 8, the motor controller 9) controls the battery 2, the engine 3, and the generator 4. The control unit (vehicle controller 7, engine controller 8, motor controller 9) stops supplying fuel to the engine 3 to stop power generation of the generator 4, and supplies power from the battery 2 to the generator 4 to cause the engine 3 to operate in a power manner, thereby consuming regenerative power, wherein, when the temperature of the catalyst (the catalyst included in the catalyst system 5) is lower than the upper limit temperature (for example, 700[°C]) that can suppress degradation of the catalyst, the closer the temperature of the catalyst (the catalyst included in the catalyst system 5) is to the upper limit temperature (for example, 700[°C]) or the faster the temperature of the catalyst (the catalyst included in the catalyst system 5) rises, the more the control unit (vehicle controller 7, engine controller 8, motor controller 9) increases the discharge amount of the battery 2.

[0109] According to the above structure, the frequency of executing the power running operation (motor running) of the engine 3 when the temperature of the catalyst exceeds the upper limit temperature (for example, 700 [° C.]) can be reduced, thereby suppressing the degradation of the catalyst. In addition, since the degradation of the catalyst can be suppressed, the amount of the catalyst (precious metal) can be reduced.

[0110] The embodiments of the present invention have been described above, but the above embodiments are merely examples of application of the present invention, and the technical scope of the present invention is not limited to the specific structures of the above embodiments. In addition, the above embodiments can be combined as appropriate.

Claims

1. A control method for a hybrid vehicle, wherein power is supplied and received between a drive motor and a battery, a generator driven by an engine for power generation charges the battery, and exhaust gas discharged from the engine is treated by a catalyst, wherein: If the charging rate of the battery exceeds a predetermined threshold value due to the regenerative power received from the drive motor, the fuel supply to the engine is stopped to stop the power generation of the generator, and the engine is powered by supplying power from the battery to the generator to consume the regenerative power. In a state where the temperature of the catalyst is lower than an upper limit temperature at which degradation of the catalyst can be suppressed, the discharge amount of the battery is increased as the temperature of the catalyst approaches the upper limit temperature or as the rate of increase in the temperature of the catalyst increases.

2. The control method of a hybrid vehicle according to claim 1, wherein: In a case where the charging rate is controlled based on a charge / discharge request curve including a center charging rate in which a charge request for the battery and a reference charging rate at which a discharge request for the battery are zero are set as initial values, and indicating a trajectory in which the lower the charging rate compared to the center charging rate, the higher the charging request, and the higher the charging rate compared to the center charging rate, the higher the discharge request, in a coordinate space having the charge / discharge current for the battery and the charging rate as axes, The charge and discharge request curve is shifted to the low charge rate side by shifting the center charge rate to a lower charge rate side than the reference charge rate as a discharge amount increase control for increasing the discharge amount of the battery.

3. The control method of a hybrid vehicle according to claim 2, wherein: The method further comprises obtaining map information related to the driving route that the vehicle is about to pass from information on the driving route to a destination of the vehicle, and performing advance charging request control to shift the center charging rate to a high charging rate side when it is predicted with reference to the map information that the vehicle will perform a high-load operation that consumes more power of the battery than a normal operation, When it is determined based on the map information that the vehicle is traveling uphill at a distance greater than or equal to a predetermined distance, the advance charging request control is preferentially performed; When it is determined based on the map information that the vehicle is traveling down a downhill road of a distance greater than or equal to a predetermined distance, the discharge amount increasing control is preferentially performed.

4. The control method of a hybrid vehicle according to claim 2, wherein: map information related to the driving route that the vehicle is about to pass through is obtained from information on the driving route to a destination of the vehicle, and when it is predicted with reference to the map information that a high-load operation that consumes more power of the battery than normal operation of the vehicle is to be performed, advance charging request control that shifts the center charging rate to a high charging rate side is performed, The amount of work performed in the high-load operation is calculated based on the map information, and the central charging rate requested by the advance charging request control is calculated as a first central charging rate based on the amount of work performed. the central charging rate requested by the discharge amount increase control is calculated as a second central charging rate based on the temperature of the catalyst or the increase rate; When the first central charging rate is higher than the second central charging rate and the first central charging rate is lower than a predetermined lower limit value, the central charging rate is set to the second central charging rate, When the first central charging rate is higher than the second central charging rate and the first central charging rate is higher than a predetermined upper limit value that is higher than the lower limit value, setting the central charging rate to the first central charging rate, In the case where the first center charging rate is higher than the second center charging rate and the first center charging rate is a value between the lower limit value and the upper limit value, the closer the first center charging rate is to the upper limit value, the center charging rate is set to a value closer to the first center charging rate, and the closer the first center charging rate is to the lower limit value, the center charging rate is set to a value closer to the second center charging rate.

5. The control method of a hybrid vehicle according to claim 4, wherein: When the first center charging rate and the second center charging rate are identical, the center charging rate is set to the first center charging rate or the second center charging rate, When the first central charging rate is lower than the second central charging rate and the first central charging rate is lower than the reference charging rate and the second central charging rate is higher than the reference charging rate, setting the central charging rate to the reference charging rate, When the first central charging rate is lower than the second central charging rate and the first central charging rate and the second central charging rate are higher than the reference charging rate, the central charging rate is set to the first central charging rate, When the first central charging rate is lower than the second central charging rate and when the first central charging rate and the second central charging rate are lower than the reference charging rate, the central charging rate is set to the second central charging rate.

6. The control method of a hybrid vehicle according to claim 1, wherein: The output of the engine driving the generator is reduced by an amount corresponding to an increase in the discharge amount of the battery.

7. A control system for a hybrid vehicle, comprising: Drive motor; A battery that supplies and receives electric power from the drive motor; a generator that generates electricity by being driven by a power generation engine and charges the battery; a catalyst that treats exhaust gas emitted from the engine; as well as a control unit that controls the battery, the engine, and the generator, If the charging rate of the battery exceeds a predetermined threshold value due to the regenerative power received from the drive motor, the control unit stops the supply of fuel to the engine to stop the power generation of the generator, supplies power from the battery to the generator to cause the engine to perform power running, thereby consuming the regenerative power, wherein: When the temperature of the catalyst is lower than an upper limit temperature at which degradation of the catalyst can be suppressed, the control unit increases the discharge amount of the battery as the temperature of the catalyst approaches the upper limit temperature or as a rate of increase in the temperature of the catalyst increases.

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