Hybrid vehicle control method and hybrid vehicle control system

Abstract

The charging rate of the battery (2) is set so that the power that can be inputted to the battery (2) becomes lower as the charging rate approaches a predetermined upper limit value, and the power that can be inputted becomes smaller than the sum of the regenerative power and the generated power when the charging rate of the battery (2) reaches the vicinity of the upper limit value due to the regenerative power received from the drive motor (1) and the generated power received from the generator (4). When power generation is requested to be stopped, fuel supply to the engine (3) is stopped and power generation by the generator (4) is stopped, power is supplied from the battery (2) to the generator (4) and the engine (3) is powered, thereby consuming regenerated power, and when the temperature of the catalyst exceeds a predetermined temperature for suppressing deterioration of the catalyst when power generation is requested to be stopped, the power generation is stopped. The supply of fuel to the engine (3) is continued to maintain the output of the engine (3), and then the output of the engine (3) is reduced when the moving average value of the current related to the sum exceeds a predetermined reference value or when the negative electrode potential of the battery (2) is lower than a predetermined reference potential.

Description

Technical Field

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

[0002] JPH8-144814A discloses prohibiting temporary fuel cut of the engine in order to reduce the degradation of the catalyst when the temperature of the catalyst for purifying exhaust gas of the engine is higher than a predetermined temperature for suppressing the degradation of the catalyst. Summary of the invention

[0003] However, a hybrid vehicle supplies power from a battery to a driving engine and drives a power generation engine to generate power, thereby charging the battery and treating exhaust gas from the engine using a catalyst. Therefore, in a hybrid vehicle, when the temperature of the catalyst is greater than or equal to a predetermined temperature, it is also necessary to avoid stopping the control of fuel supply to the engine.

[0004] However, the input power that can be input to the battery is set to be lower as it approaches the upper limit of the battery's charge rate in order to protect the battery. Therefore, the battery is supplied with the generated power supplied by the generator and the regenerative power generated by the drive motor so that the battery's charge rate reaches near the upper limit. If the input power is lower than the sum of the generated power and the regenerative power, the fuel supply to the engine is stopped, and it is necessary to supply power from the battery to the generator to drive the engine (internal combustion engine) (power operation), that is, to discharge and consume the regenerative power through the operation of the motor. On the other hand, if the catalyst is exposed to a thin atmosphere in a state exceeding the specified temperature, it will deteriorate. Therefore, if the fuel supply to the engine is stopped in a state where the temperature of the catalyst exceeds the specified temperature, the catalyst may deteriorate.

[0005] Therefore, an object of the present invention is to provide a hybrid vehicle control method and a hybrid vehicle control system for suppressing catalyst degradation by avoiding motor operation of an engine in a state where the temperature of the catalyst exceeds a predetermined temperature.

[0006] According to one embodiment of the present invention, a control method for a hybrid vehicle is provided, wherein power is supplied and received between a drive motor and a battery, and a generator driven by an engine for power generation charges the battery according to a power generation request accompanied by a driver's operation, and exhaust gas discharged from the engine is treated by a catalyst. In the control method, the charging rate of the battery is set so that the closer to a prescribed upper limit value, the lower the input power to the battery. If the charging rate of the battery reaches the vicinity of the upper limit value due to the regenerative power received from the drive motor and the generated power received from the generator, and the input power becomes less than the sum of the regenerative power and the generated power, the fuel supply to the engine is stopped to stop the power generation of the generator, and the power is supplied from the battery to the generator to cause the engine to perform power running, thereby consuming the regenerative power. Furthermore, when the temperature of the catalyst is less than or equal to the prescribed temperature for suppressing the degradation of the catalyst when the power generation request is stopped, the fuel supply to the engine is stopped. Furthermore, when the temperature of the catalyst exceeds a specified temperature when the power generation is requested to stop, fuel is continuously supplied to the engine to maintain the engine output, and then when the moving average value of the current involving the total exceeds a specified reference value or the negative electrode potential of the battery is lower than a specified reference potential, the engine output is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a schematic diagram of a control system of a hybrid vehicle according to the present embodiment.

[0008] Figure 2 It is a diagram showing a control block of a control system of a hybrid vehicle according to the present embodiment.

[0009] Figure 3 This is a first control flow of the hybrid vehicle control system according to the present embodiment.

[0010] Figure 4 This is the second control flow of the hybrid vehicle control system according to the present embodiment.

[0011] Figure 5 This is the third control flow of the hybrid vehicle control system according to the present embodiment.

[0012] Figure 6 This is the fourth control flow of the hybrid vehicle control system according to the present embodiment.

[0013] Figure 7 This is a diagram showing transition of an operating point when the engine output is reduced in the hybrid vehicle control system according to the present embodiment.

[0014] Figure 8 This is a first timing chart of the control system of the hybrid vehicle according to the present embodiment.

[0015] Fig. 9 This is a second timing chart of the hybrid vehicle control system according to the present embodiment. DETAILED DESCRIPTION

[0016] [Basic Structure of the Present Embodiment]

[0017] 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).

[0018] The drive motor 1 is mechanically coupled to the drive wheel 12 via the speed reducer 10 and the drive shaft 11, and receives power from the battery 2 to drive the drive wheel 12. In addition, the drive motor 1 generates regenerative power when reducing the rotation of the drive wheel 12.

[0019] The battery 2 is, for example, a lithium-ion battery, and 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 .

[0020] 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.

[0021] The generator 4 supplies the generated power to the battery 2. In addition, the generator 4 sometimes receives power from the battery 2 to make the engine 3, which has stopped fuel supply, perform power running (motor operation). In addition to consuming the 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.

[0022] 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 .

[0023] 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.

[0024] The vehicle controller 7 outputs a motor torque command value to the motor controller 9 based on the accelerator opening indicated by the accelerator pedal 13 .

[0025] The vehicle controller 7 outputs a driving power generation request (power generation permission flag) to the engine controller 8 in response to the driver's operation of the accelerator pedal 13 , and stops the driving power generation request when the vehicle speed is constant and a predetermined time has passed or the vehicle speed starts to decelerate.

[0026] The vehicle controller 7 inputs information on the catalyst temperature via the engine controller 8. If the catalyst temperature exceeds a specified temperature (e.g., 700[°C]) for suppressing catalyst degradation when the driving power generation request is stopped, a catalyst power generation request (power generation permission flag) is output to the engine controller 8.

[0027] The vehicle controller 7 inputs information on the charging rate of the battery 2, the negative electrode potential of the battery 2, the regenerative power supplied from the drive motor 1 to the battery 2 (the regenerative power supplied from the drive motor 1 to the battery 2 by the first inverter described later), and the generated power supplied from the generator 4 to the battery 2 (the generated power supplied from the generator 4 to the battery 2 by the second inverter described later).

[0028] The vehicle controller 7 sets the inputtable electric power that can be input to the battery 2 in accordance with the charging rate of the battery 2 in order to protect the battery 2 .

[0029] The inputtable power is set to a reference power that is sufficiently greater than the power generated by the generator 4 when the engine 3 is operated at the optimal fuel operating point (optimal fuel operating point power), for example, when the charging rate of the battery 2 is less than or equal to a predetermined threshold value (e.g., 70[%]). Here, the reference power is set, for example, so that the difference between the reference power and the optimal operating point power is greater than the maximum value of the regenerative power described later. On the other hand, if the inputtable power exceeds the threshold value, it starts to decrease and is set based on a line where the upper limit value (e.g., 80[%]) is zero.

[0030] When the catalyst power generation request is not output, the vehicle controller 7 compares the sum of the generated power and the regenerated power with the inputtable power, and stops the drive power generation request if the inputtable power is lower than the sum, and outputs a power running operation command to the motor controller 9 .

[0031] The vehicle controller 7 calculates a moving average value (e.g., an average value of the current over 10 [s]) of the sum of the generated power and the regenerated power during the period when the catalyst power generation request is output and when the charging rate is lower than a predetermined threshold value. If the moving average value reaches a reference value described later, the vehicle controller 7 calculates a moving average value (e.g., an average value of the current over 10 [s]) of the current related to the sum of the generated power and the regenerated power ... Figure 7The illustrated path changes the engine torque command value and the engine speed command value in such a manner that the output of the engine 3 is reduced.

[0032] The vehicle controller 7 outputs the engine torque command value to the engine controller 8 and the engine speed command value to the motor controller 9. Alternatively, the vehicle controller 7 outputs the engine speed command value to the engine controller 8, and the engine controller 8 controls the torque and speed of the engine 3.

[0033] Even when the catalyst power generation request is output, if the charging rate of the battery 2 reaches a predetermined upper limit value (eg, 80[%]), the vehicle controller 7 stops the catalyst power generation request.

[0034] When the engine controller 8 receives a driving power generation request from the vehicle controller 7, it starts supplying fuel to the engine 3 and starts the engine 3. The engine controller 8 controls the output of the engine 3 (the output of the generator 4) based on the engine torque command value and the engine speed command value input from the vehicle controller 7.

[0035] If the driving power generation request (power generation permission flag) and the catalyst power generation request (power generation permission flag) input from the vehicle controller 7 stop, the engine controller 8 stops the fuel supply to the engine 3 and stops the driving of the engine 3 (power generation of the generator 4).

[0036] The engine controller 8 acquires information on the temperature of a catalyst (for example, titanium (Ti)) included in the catalyst system 5 , and outputs the information to the vehicle controller 7 .

[0037] The motor controller 9 controls the output of the drive motor 1 based on the motor torque command value. In addition, when receiving the engine speed command value from the vehicle controller 7, the motor controller 9 controls the speed of the generator 4 according to the engine speed command value.

[0038] When receiving the power running operation command from the vehicle controller 7 , the motor controller 9 drives the generator 4 using the electric power from the battery 2 and causes the engine 3 to which the fuel supply is stopped to perform the power running operation (motor operation).

[0039] 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.

[0040] The first inverter converts the DC power of the battery 2 into AC power based on the motor torque command value and outputs the AC power to the drive motor 1. When the drive motor 1 generates regenerative power, the first inverter converts the regenerative power into DC power to charge the battery 2.

[0041] 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 into an AC voltage and outputs it to the generator 4.

[0042] [Control module]

[0043] Figure 2 FIG. 2 is a diagram showing a control module of a control system of a hybrid vehicle according to the present embodiment. Figure 2 As shown, the controller 7 is composed of a first judgment element 701, a second judgment element 702, a third judgment element 703, a fourth judgment element 704, a reversal element 705, a flag setting unit 706, a first corresponding map 707, a second corresponding map 708, a third corresponding map 709, a first power selection element 710, a second power selection element 711, and a power generation control operation unit 712.

[0044] The first judgment element 701 (which may also be the engine controller 8 ) detects the temperature of the catalyst, and when the temperature of the catalyst exceeds a predetermined temperature (eg, 700° C.) for suppressing degradation of the catalyst, outputs a catalyst power generation request to the fourth judgment element 704 .

[0045] The second judgment element 702 compares the charging rate (SOC (State Of Charge)) of the battery 2 with the upper limit value (for example, 80[%]). When the charging rate of the battery 2 is less than or equal to the upper limit value, a High "1" signal (flag) is output to the fourth judgment element 704. When the charging rate of the battery 2 exceeds the upper limit value, a LOW "0" signal is output to the fourth judgment element 704.

[0046] The third judgment element 703 judges whether the engine 3 is in a driving state, that is, whether the generator 4 is in a power generation state. When the engine 3 is in a driving state, a High "1" signal (flag) is output to the fourth judgment element 704. When the engine 3 is stopped, a LOW "0" signal is output to the fourth judgment element 704.

[0047] If a request for catalyst power generation is input from the first judgment element 701 and a HIGH "1" signal is input from the second judgment element 702 and the third judgment element 703, the fourth judgment element 704 outputs a HIGH "1" signal to the flag setting unit 706, and in all other cases, a LOW "0" signal is output to the flag setting unit 706.

[0048] The inversion element 705 inverts the signal output by the third determination element 703 and outputs the inversion signal to the flag setting unit 706 .

[0049] The flag setting unit 706 receives the signal of the fourth determination element 704 and sets it as a flag. When the output from the inversion element 705 is HIGH "1", the flag setting unit 706 resets the set flag (sets it to LOW "0").

[0050] The first correspondence diagram 707 is data showing the correlation between the moving average value (e.g., the average value of the input current for 10 [s]) of the input current (generated current and regenerative current) to the battery 2 and the first allowable generated power. When the moving average value is less than or equal to the reference value, the first allowable generated power is the same value as the fuel efficiency best operating point power, and starts to decrease if it exceeds the reference value, and becomes zero if it reaches a specified value higher than the reference value. In addition, as a higher-level concept of the moving average value of the input current to the battery 2, there is a history (integral amount) of the input current of the battery 2.

[0051] The second correspondence diagram 708 is data showing the correlation between the negative electrode potential of the battery 2 and the second allowable generated power. When the negative electrode potential is greater than or equal to the reference potential (e.g., 1 [V]), the second allowable generated power is the same value as the fuel efficiency best operating point power, and starts to decrease if it is lower than the reference potential, and becomes zero if it reaches the ground potential (e.g., 0 [V]) lower than the reference potential. In addition, the negative electrode potential is related to the charging rate of the battery 2, but for example, when the negative electrode potential is 0 [V], it corresponds to the upper limit value of the charging rate (e.g., 80 [%]), and if the negative electrode potential is lower than 0 [V], metal Li may be precipitated at the negative electrode.

[0052] The third correspondence diagram 709 is data showing the correlation between the charging rate of the battery 2 and the third allowable generated power. When the charging rate of the battery 2 is less than or equal to a predetermined threshold value (e.g., 70[%]), the third allowable generated power is the same value as the fuel efficiency best operating point power, and starts to decrease when it exceeds the threshold value (e.g., 70[%]), and becomes zero when it reaches the upper limit value (e.g., 80[%]). That is, the third allowable generated power decreases in conjunction with the decrease in the inputtable power, and the upper limit value (e.g., 80[%]) is zero.

[0053] The first allowable generated power, the second allowable generated power, and the third allowable generated power are each appropriately set so that the sum of the first allowable generated power and the regenerative power (maximum value) input to the battery 2 does not exceed the inputtable power of the battery 2 .

[0054] The first power selection element 710 can output the lowest power among, for example, the first allowable generated power, the second allowable generated power, the third allowable generated power, and the fuel efficiency best operating point power to the second power selection element 711 .

[0055] Furthermore, the first power selection element 710 can also output the lowest power among the first allowable generated power, the second allowable generated power, the third allowable generated power, and the fuel efficiency best operating point power, to the second power selection element 711 .

[0056] The second power selection element 711 sets the power selected by the first power selection element 710 as the catalyst power generation request power when the flag set by the flag setting unit 706 is HIGH "1", and selects zero as the catalyst power generation request power when the flag is LOW "0".

[0057] The power generation request for driving and the power generation request for catalyst are input to the power generation control calculation unit 712. The power generation request for driving is generated, for example, by the driver stepping on the accelerator pedal 13, and the output of the engine 3 (the power generated by the generator 4) also changes according to the amount of the stepping. Moreover, after the vehicle speed becomes constant, a predetermined time has passed, or the vehicle speed enters a deceleration stage and becomes zero. If the temperature of the catalyst exceeds a predetermined temperature (for example, 700 [°C]) when the power generation request for driving (the power generation request for driving) is stopped, the power generation request for catalyst (the power generation request for catalyst) is input.

[0058] When the power generation control calculation unit 712 receives the power generation request for driving or the power generation request for catalyst, it outputs a power generation permission flag to the engine controller 8 .

[0059] The power generation control calculation unit 712 outputs the engine torque command value based on the requested power for driving power generation, or the engine torque command value based on the requested power for catalyst power generation, to the engine controller 8, and outputs the engine speed command value based on the requested power for driving power generation, or the engine speed command value based on the requested power for catalyst power generation, to the motor controller 9.

[0060] [Control Flow]

[0061] Figure 3 This is a first control flow of the hybrid vehicle control system of the present embodiment. The first control flow is a control using a moving average value of the input current (generated current+regenerative current) of the battery 2 .

[0062] In step S1 , the vehicle controller 7 stops the driving power generation request when the state of charge (SOC) is equal to or greater than a predetermined value (a value lower than a threshold value described later) or when the vehicle speed is decelerating.

[0063] In step S2 , the vehicle controller 7 determines whether the temperature of the catalyst exceeds a predetermined temperature (eg, 700[° C.]), and proceeds to step S3 if the determination is YES, and proceeds to step S4 if the determination is NO.

[0064] In step S3 , the vehicle controller 7 stops the fuel supply to the engine 3 and stops the output of the engine 3 by stopping the output of the power generation permission flag to the engine controller 8 .

[0065] In step S4 , the vehicle controller 7 (engine controller 8 , motor controller 9 ) starts a catalyst power generation request, and causes the engine 3 to continue to generate power at the fuel-efficient operating point.

[0066] In step S5, the vehicle controller 7 determines whether the moving average value of the input current (generated current + regenerated current) of the battery 2 exceeds the reference value (reference value in the first corresponding diagram). If it is YES, it proceeds to step S6, and if it is NO, it proceeds to step S7.

[0067] In step S6 , the vehicle controller 7 outputs an engine torque command value corresponding to the first allowable generated power to the engine controller 8 and an engine speed command value to the motor controller 9 based on the moving average value and the first map 707 , thereby reducing the output of the engine 3 .

[0068] In step S7 , the vehicle controller 7 (engine controller 8 , motor controller 9 ) continues to cause the engine 3 to generate electric power at the operating point with the best fuel efficiency.

[0069] In step S8 , the vehicle controller 7 determines whether the temperature of the catalyst is less than or equal to a predetermined temperature, and if so, proceeds to step S9 , and if so, proceeds to step S4 .

[0070] In step S9 , the vehicle controller 7 stops the catalyst power generation request, sets the engine torque command value and the engine speed command value to zero, and stops the power generation permission flag output to the engine controller 8 , thereby stopping the output of the engine 3 .

[0071] Furthermore, as step S5, the vehicle controller 7 may calculate whether the negative electrode potential of the battery 2 is lower than the reference potential, and proceed to step S6 if the calculation is YES, and proceed to step S7 if the calculation is NO.

[0072] Similarly, as step S6, the vehicle controller 7 can output the engine torque command value corresponding to the second allowable generated power to the engine controller 8 and the engine speed command value to the motor controller 9 based on the value of the negative electrode potential and the second corresponding map 708, thereby reducing the output of the engine 3.

[0073] Figure 4 This is the second control flow of the control system of the hybrid vehicle of this embodiment. The second control flow is based on the charging rate of the battery 2 and the third map 709 ( Figure 2 ) and set the output process of engine 3.

[0074] Steps S1 to S4 and S7 to S9 are common to the first control flow.

[0075] After step S4, in step S5A, the vehicle controller 7 determines whether the charging rate (SOC) of the battery 2 is higher than a threshold value (for example, 70[%]), and if so, proceeds to step S6, and if so, proceeds to step S7.

[0076] In step S6A, the vehicle controller 7 calculates the charge rate (SOC) of the battery 2 and the third map 709 ( Figure 2 ) The third allowable generated power is calculated, and the engine torque command value corresponding to the third allowable generated power is output to the engine controller 8, and the engine speed command value is output to the motor controller 9, thereby reducing the output of the engine 3.

[0077] Figure 5 This is the third control flow of the hybrid vehicle control system of this embodiment. The third control flow is a flow in the case where the charge rate (SOC) of the battery 2 reaches the upper limit value (e.g., 80[%]) immediately after the catalyst power generation request is initiated. In the third control flow, steps S1-S4 and steps S7-S9 are the same as those in the first control flow.

[0078] After step S4, in step S5B, the vehicle controller 7 determines whether the charging rate (SOC) of the battery 2 has reached an upper limit value (eg, 80[%]), and if so, proceeds to step S9, and if so, proceeds to step S7.

[0079] Figure 6 This is the fourth control flow of the hybrid vehicle control system of the present embodiment. The fourth control flow is similar to the second control flow and is a flow when the output of the engine 3 is difficult to decrease even when control is performed to decrease the output of the engine 3.

[0080] Regarding the control system of the engine 3, there is a lag time (e.g., 2 [s]) until the engine torque command value and the engine speed command value are reflected as the actual engine torque and the actual engine speed. However, for example, when a supercharger that uses the exhaust gas of the engine 3 to drive and take in external air is installed on the engine 3, the response to the command of the output of the engine 3 is delayed compared with the above-mentioned lag time, and as a result, the state in which the output (especially the torque) is difficult to reduce continues, and there is a possibility of knocking (sudden increase in speed) of the engine 3. The conditions for the occurrence of knocking of the engine 3 are that the output of the engine 3 is less than the sum of the input power, the power consumption of the vehicle (auxiliary equipment), and the friction of the engine 3, and the intake manifold pressure of the engine 3 is higher than the specified pressure.

[0081] Therefore, with regard to the fourth control process, when the response (actual engine torque and actual engine speed, especially actual engine torque) to the output command of the engine 3 (engine torque command value and engine speed command value) is delayed compared to the above-mentioned lag time (for example, 2 [s]) for a period greater than or equal to a specified time (for example, 1 [s]), control is performed to stop the fuel supply to the engine 3 and stop the output of the engine 3.

[0082] Regarding the fourth control flow, step S6B is arranged between step S6A and step S8.

[0083] In step S6B, the vehicle controller 7 determines whether the response (actual engine torque, actual engine speed) to the command (engine torque command value, engine speed command value) of the output of the engine 3 is longer than the lag time of the control system of the engine 3 for a time greater than or equal to a predetermined time (for example, 1 [s]), and if it is YES, it proceeds to step S9, and if it is NO, it proceeds to step S8. In addition, the actual engine torque is estimated based on the output current of the generator 4, and the actual engine speed is measured by a tachometer installed on the engine 3.

[0084] [Operation point of engine 3]

[0085] Figure 7 This is a diagram showing transition of the operating point when the output of the engine 3 is reduced in the control system of the hybrid vehicle according to the present embodiment. Figure 7 The coordinate space in which the horizontal axis represents the engine speed and the vertical axis represents the engine torque shows the relationship between the operating point (speed, torque) of the engine 3 , the α line (efficiency operation line), and the equal power line (inputtable power).

[0086] Figure 8 The isoelectric lines shown represent the power that can be input to the battery 2 in the coordinate space, and the closer to the origin of the coordinate space, the lower the input power.

[0087] In the present embodiment, the operating point (A) of the engine 3 is initially set to a fuel-efficient operating point involving a fuel-efficient rotation speed (eg, 2000 [rpm]) and a fuel-efficient torque.

[0088] When the charging rate (SOC) of battery 2 is less than or equal to a threshold value (for example, 70[%]), the isoelectric lines indicating the input power are arranged at a higher position than (A). If the charging rate is higher than the threshold value, the isoelectric lines move toward the origin and (A) is at a higher position than the isoelectric lines indicating the input power, and the power becomes greater than the power represented by the isoelectric lines.

[0089] Therefore, in the present embodiment, the operating point is moved in accordance with the change (reduction in the inputtable power) of the isoelectric line indicating the inputtable power along the α line (an efficient operation line indicating the trajectory of the rotation speed and torque at which the fuel consumption is minimized) including the fuel consumption optimal operation point (A). Furthermore, when the operating point (B) that becomes the lower limit rotation speed (variable) of the control system of the engine 3 is reached, the torque is reduced while the rotation speed is maintained, and finally the operating point (D) where the torque is zero is set.

[0090] At the operating point (D), the charging rate of the battery 2 reaches the upper limit value (e.g., 80% %), the generator 4 does not generate electricity, and the engine 3 rotates following the rotation of the generator 4. By reducing the output (the product of the rotation speed and the torque) of the engine 3, the temperature of the catalyst can be reduced without the catalyst being in a lean atmosphere.

[0091] However, for example, whenever the output (torque command value) of the engine 3 is reduced from the operating point (B) to the operating point (D), the output (actual torque) of the engine 3 as a response thereof does not sufficiently decrease even after the lag time of the engine control system as described above, and the actual operating point is located at a position higher than the equal power line. In this case, as described above, the input power (regenerative power + generated power) of the battery 2 is higher than the input power, and the excess power is consumed, so there is a possibility that knocking (sudden increase in rotation speed) of the engine 3 may occur.

[0092] Therefore, in the present embodiment, when it is determined that the above situation may occur at the operating point (C) between the operating point (B) and the operating point (D), that is, when the response (actual engine torque, actual engine speed) to the command (engine torque command value, engine speed command value) of the output of the engine 3 is longer than the lag time of the control system of the engine 3 for a time greater than or equal to a prescribed time (e.g., 1 [s]), the fuel supply to the engine 3 is stopped and the operating point of the engine 3 is set to the operating point (D) (origin). As a result, the knocking (sudden increase in speed) of the engine 3 is suppressed. In addition, even when the temperature of the catalyst is higher than the prescribed temperature (e.g., 700 [°C]) when the output of the engine 3 is stopped, it is not necessary to make a request for power generation for the catalyst again.

[0093] [1st Timing Diagram]

[0094] Figure 8 1 is a first timing diagram of the control system of the hybrid vehicle of the present embodiment. Here, a timing diagram is shown for a case where the temperature of the catalyst exceeds a predetermined temperature (e.g., 700[°C]) for suppressing catalyst degradation during vehicle acceleration, and then the charge rate (SOC) of the battery 2 reaches near an upper limit value (e.g., 80[%]) during the deceleration phase, thereby limiting the power that can be input to the battery 2. In addition, the first timing diagram shows a moving average value ( Figure 2 The situation where the engine output request (engine torque command value, engine speed command value) is controlled based on the first allowable generated power).

[0095] At time t0, the vehicle is accelerating and the driving power generation request ( Fig. 9 The power generation request A) is in the ON state, and the engine 3 operates at an operating point where the output is higher than the fuel efficiency best operating point based on the accelerator opening.

[0096] At time t1, the driver reduces the accelerator opening and makes the vehicle speed constant, and the engine 3 is at the optimal fuel consumption operation point ( Figure 8 The action is performed at the action point (A).

[0097] At time t2 after a predetermined time has passed from time t1, the vehicle controller 7 turns the driving power generation request (power generation request A) to an OFF state. However, at time t2, the temperature of the catalyst exceeds a predetermined temperature (e.g., 700[°C]), so the driving power generation request (power generation request A) is turned to an OFF state, and the catalyst power generation request (power generation request B) is turned to an ON state.

[0098] At time t3, the driver further reduces the accelerator opening and decelerates the vehicle to generate regenerative power. In addition, the catalyst power generation request (power generation request B) is in the ON state, so the output of the engine 3 is kept at the fuel efficiency best operating point ( Figure 8 The action is performed at the action point (A).

[0099] When time t3 has passed, the battery 2 is charged with the regenerative electric power, and the moving average value of the input current to the battery 2 starts to increase.

[0100] At time t4, if the moving average value of the input current to the battery 2 exceeds the reference value (reference value in the first corresponding diagram 707), the engine output request (engine torque command value, engine speed command value) is set based on the first allowable generated power, thereby reducing the output of the engine 3 (the generated power of the generator 4). The first allowable generated power is set to react sensitively to the increase in the moving average value at the stage where the moving average value exceeds the reference value and to be significantly reduced, thereby also significantly reducing the output of the engine 3 (the generated power of the generator 4). In addition, the reference value is set to the value that the moving average value reaches before the input power starts to be restricted based on the charging rate of the battery 2. Therefore, as a result, the increase in the moving average value is suppressed after time t4. In addition, when the output of the engine 3 is reduced, along Figure 8 The α line shown decreases from the optimal operating point for fuel efficiency.

[0101] At time t8, the engine speed reaches the lower speed limit ( Figure 8 action point (B).

[0102] At time t9, the engine torque reaches zero ( Figure 8 action point (D).

[0103] At time t10, if the catalyst temperature is less than or equal to a predetermined temperature (eg, 700[°C]), the vehicle controller 7 turns the catalyst power generation request (power generation request B) to an OFF state, and the engine controller 8 stops the fuel supply to the engine 3 to stop the output of the engine 3.

[0104] In the present embodiment, the operating state of the engine 3 is the power generation state from time t0 to time t10. That is, in the present embodiment, the output of the engine 3 (the power generated by the generator 4) is reduced in accordance with the input power that decreases as the charging rate of the battery 2 increases, and this is continued until the temperature of the catalyst is less than or equal to a predetermined temperature (e.g., 700 [°C]), thereby preventing the catalyst from being exposed to a rarefied atmosphere and decreasing to a predetermined temperature (e.g., 700 [°C]), thereby suppressing the degradation of the catalyst.

[0105] On the other hand, if the output of the engine 3 is not reduced in the above manner after time t4 and the operation at the fuel efficiency optimum operation point is continued, the moving average value (dashed line) continues to increase. Furthermore, at time t5, the inputtable power (dashed line) decreases while the charge rate (SOC) of the battery 2 increases. Furthermore, if the inputtable power (dashed line) is lower than the regenerative power (dashed line) and the generated power ( Figure 8 If the sum of the total ...

[0106] [Second Timing Diagram]

[0107] Fig. 9 This is the second timing diagram of the control system of the hybrid vehicle of this embodiment. The application of the second timing diagram is the same as that of the first timing diagram, based on the charging rate of the battery 2 and the third correspondence diagram 709 (the third allowable generated power, Figure 2 ) to control the engine output request (engine torque command value, engine speed command value).

[0108] In the second timing chart, the operations at time t0 - t3 and time t8 - t10 are the same as those in the first timing chart.

[0109] At time t5, if the power that can be input to the battery 2 starts to decrease, the third permissible generated power ( Figure 2 ) is reduced in conjunction with it, so that the engine output request (engine torque command value, engine speed command value) is reduced. In this way, the output of the engine 3 (the power generated by the generator 4) is also reduced in conjunction with the reduction of the inputtable power, thereby reducing the situation where the sum of the regenerative power and the generated power is greater than the inputtable power.

[0110] In the first timing diagram and the second timing diagram, for example, when the charging rate (SOC) of the battery 2 reaches an upper limit value (e.g., 80[%]) before the temperature of the catalyst is less than or equal to a specified temperature (e.g., 700[°C]), the vehicle controller 7 changes the power generation request for the catalyst (power generation request B) (power generation permission flag) to an OFF state, and the motor controller 9 stops the fuel supply to the engine 3 and stops the output of the engine 3 (power generation of the generator 4).

[0111] In addition, when the output of the engine 3 is reduced (especially during the period from time t8 to time t9), when the response (actual engine torque and actual engine speed, especially actual engine torque) to the command for the output of the engine 3 (engine torque command value and engine speed command value) continues to lag behind the lag time of the control system of the engine 3 for a period greater than or equal to a specified time (for example, 1 [s]), the engine controller 8 (vehicle controller 7) stops the fuel supply to the engine 3 and stops the output of the engine 3.

[0112] [Effects of this embodiment]

[0113] 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, and the generator 4 driven by the engine 3 for power generation charges the battery 2 according to the power generation request (power generation request for driving) accompanied by the driver's operation, and the exhaust gas discharged from the engine 3 is treated by the catalyst (catalyst system 5), wherein the charging rate (SOC) of the battery 2 is set to be closer to a prescribed upper limit value (e.g., 80[%]), the lower the input power to the battery 2, and if the charging rate (SOC) of the battery 2 reaches the vicinity of the upper limit value (e.g., 80[%]) due to the regenerative power received from the drive motor 1 and the generated power received from the generator 4, and the input power becomes less than the sum of the regenerative power and the generated power, the fuel supply to the engine 3 is stopped to make the The generator 4 stops generating electricity, and power is supplied from the battery 2 to the generator 4 so that the engine 3 is powered and operated to consume regenerated power. When the power generation request (power generation request for driving) stops and the temperature of the catalyst (the catalyst included in the catalyst system 5) is less than or equal to a specified temperature (for example, 700 [°C]) for suppressing degradation of the catalyst, the fuel supply to the engine 3 is stopped. When the power generation request (power generation request for driving) stops and the temperature of the catalyst (the catalyst included in the catalyst system 5) exceeds a specified temperature (for example, 700 [°C]), the fuel supply to the engine 3 is continued to maintain the output of the engine 3, and then when the moving average value of the current involving the total exceeds a specified reference value or the negative electrode potential of the battery 2 is lower than a specified reference potential, the output of the engine 3 is reduced.

[0114] According to the above method, by appropriately setting the reference value or reference voltage, the output of the engine 3 (the power generated by the generator 4) can be reduced in accordance with the input power that decreases as the charging rate of the battery 2 increases, and the output of the engine 3 can be continued until the temperature of the catalyst is less than or equal to a predetermined temperature (for example, 700 [° C.]). Therefore, the motor operation of the engine 3 is not performed, that is, the catalyst is not exposed to a lean atmosphere and lowered to a predetermined temperature (for example, 700 [° C.]), thereby suppressing the degradation of the catalyst.

[0115] In addition, 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, and the generator 4 driven by the engine 3 for power generation charges the battery 2 according to the power generation request (power generation request for driving) accompanied by the driver's operation, and the exhaust gas discharged from the engine 3 is treated by the catalyst (catalyst system 5), wherein the charging rate (SOC) of the battery 2 is set so that the closer it is to a prescribed upper limit value (e.g., 80[%]), the lower the input power to the battery 2. If the charging rate (SOC) of the battery 2 reaches the vicinity of the upper limit value (e.g., 80[%]) due to the regenerative power received from the drive motor 1 and the generated power received from the generator 4, the input power becomes less than the sum of the regenerative power and the generated power. The sum is as follows: when the power generation request (driving power generation request) is stopped, the fuel supply to the engine 3 is stopped, and the power generation of the generator 4 is stopped; the power is supplied from the battery 2 to the generator 4, and the engine 3 is driven to run and consume the regenerated power; when the temperature of the catalyst (the catalyst included in the catalyst system 5) is less than or equal to a prescribed temperature (e.g., 700[°C]) for suppressing the degradation of the catalyst, the fuel supply to the engine 3 is stopped; when the power generation request (driving power generation request) is stopped, the temperature of the catalyst (the catalyst included in the catalyst system 5) exceeds a prescribed temperature (e.g., 700[°C]), the fuel supply to the engine 3 is continued, thereby maintaining the output of the engine 3; and then, based on the input power (the charging rate of the battery 2 and the third correspondence diagram 709 ( Figure 2 )) changes, causing the output of engine 3 to decrease.

[0116] According to the above method, if the inputtable power starts to decrease, the output of the engine 3 (the power generated by the generator 4) also decreases immediately, so that the sum of the regenerative power and the generated power can be reduced to be greater than the inputtable power, and the output of the engine 3 is continued until the temperature of the catalyst is less than or equal to a predetermined temperature (for example, 700 [°C]). Therefore, the motor operation of the engine 3 is not performed, that is, the catalyst is not exposed to a lean atmosphere and lowered to a predetermined temperature (for example, 700 [°C]), thereby suppressing the degradation of the catalyst.

[0117] In the present embodiment, when the state of charge (SOC) of the battery 2 exceeds an upper limit value (eg, 80% ) , the output of the engine 3 is stopped.

[0118] This can suppress the degradation of the battery 2 .

[0119] In the present embodiment, the output of the engine 3 is controlled based on the speed command value and the torque command value, and when the response to the speed command value and the torque command value is delayed compared to the lag time of the control system of the engine 3 for a period greater than or equal to a specified time while the output of the engine 3 is being reduced, the output of the engine 3 is stopped.

[0120] According to the above method, knocking (sudden increase in the speed of the engine 3) of the engine 3 can be prevented. In addition, when the output of the engine 3 is reduced, in the coordinate space where the speed of the engine 3 and the torque of the engine 3 are set as axes, after the speed command value and the torque command value are reduced from the fuel efficiency best operating point based on the efficiency operation line (α line) represented as the trajectory of the efficiency operation point when the output of the engine 3 is reduced, including the fuel efficiency best operating point where the output efficiency of the engine 3 is the highest, if the speed reaches a predetermined lower limit speed, the torque command value is reduced to zero while the speed is maintained.

[0121] The control system of the hybrid vehicle according to the present embodiment includes: a drive motor 1; a battery 2, which supplies and receives electric power to and from the drive motor 1; a generator 4, which is driven by an engine 3 for power generation and generates electricity in accordance with a power generation request (power generation request for driving) accompanied by a driver's operation to charge the battery 2; a catalyst (catalyst system 5), which processes exhaust gas discharged from the engine 3; and a control unit (vehicle controller 7, engine controller 8, motor controller 9), which controls the battery 2, the engine 3 and the generator 4, and the charge rate (SOC) of the battery 2 is set to be closer to a prescribed upper limit value (e.g., 80 [%]), the lower the input power to the battery 2. If the charge rate of the battery 2 reaches the vicinity of the upper limit value (e.g., 80 [%]) due to the regenerative power received from the drive motor 1 and the generated power received from the generator 4, and the input power becomes less than the sum of the regenerative power and the generated power, the control unit (vehicle controller 7, engine controller 8, 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 the fuel supply to the engine 3 to stop the power generation of the generator 4, supplies power from the battery 2 to the generator 4 and causes the engine 3 to perform power running to consume regenerated power, wherein, when the power generation request (driving power generation request) stops and the temperature of the catalyst (the catalyst included in the catalyst system 5) is less than or equal to a specified temperature (for example, 700 [°C]) for suppressing deterioration of the catalyst, the control unit (vehicle controller 7, engine controller 8, motor controller 9) stops the fuel supply to the engine 3, and when the temperature of the catalyst (the catalyst included in the catalyst system 5) exceeds a specified temperature (for example, 700 [°C]) when the power generation request stops, continues to supply fuel to the engine 3 to maintain the output of the engine 3, and then reduces the output of the engine 3 when the moving average value of the current involving the total exceeds a specified reference value or when the negative electrode potential of the battery 2 is lower than a specified reference potential.

[0122] According to the above configuration, by appropriately setting the reference value or reference voltage, the output of the engine 3 (the power generated by the generator 4) can be reduced in accordance with the input power that decreases as the charging rate of the battery 2 increases, and the output of the engine 3 can be continued until the temperature of the catalyst is less than or equal to a predetermined temperature (for example, 700 [° C.]). Therefore, the motor operation of the engine 3 is not performed, that is, the catalyst is not exposed to a lean atmosphere and lowered to a predetermined temperature (for example, 700 [° C.]), thereby suppressing the degradation of the catalyst.

[0123] 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 driving motor and a battery, a generator driven by an engine for power generation charges the battery in response to a power generation request accompanied by a driver's operation, and exhaust gas discharged from the engine is treated using a catalyst, wherein: The charging rate of the battery is set so that the closer it is to a predetermined upper limit value, the lower the power that can be input to the battery. If the charging rate of the battery reaches the vicinity of the upper limit value due to the regenerative power received from the drive motor and the generated power received from the generator, and the input power becomes less than the sum of the regenerative power and the generated power, the fuel supply to the engine is stopped to stop the power generation of the generator, and the generator is supplied with power from the battery to operate the engine for power running, thereby consuming the regenerative power. When the temperature of the catalyst is lower than or equal to a predetermined temperature for suppressing degradation of the catalyst when the power generation request is stopped, stopping the supply of fuel to the engine; When the temperature of the catalyst exceeds the specified temperature when the power generation request is stopped, the fuel supply to the engine is continued to maintain the output of the engine, and then the output of the engine is reduced when the moving average of the current involved in the total exceeds a specified reference value or the negative electrode potential of the battery is lower than a specified reference potential.

2. A control method for a hybrid vehicle, wherein power is supplied and received between a driving motor and a battery, a generator driven by an engine for power generation charges the battery in response to a power generation request accompanied by a driver's operation, and exhaust gas discharged from the engine is treated using a catalyst, wherein: The charging rate of the battery is set so that the closer it is to a predetermined upper limit value, the lower the power that can be input to the battery. If the charging rate of the battery reaches the vicinity of the upper limit value due to the regenerative power received from the drive motor and the generated power received from the generator, and the input power becomes less than the sum of the regenerative power and the generated power, the fuel supply to the engine is stopped to stop the power generation of the generator, and the generator is supplied with power from the battery to operate the engine for power running, thereby consuming the regenerative power. When the temperature of the catalyst is lower than or equal to a predetermined temperature for suppressing degradation of the catalyst when the power generation request is stopped, stopping the supply of fuel to the engine; When the temperature of the catalyst exceeds the predetermined temperature when the power generation request is stopped, the fuel supply to the engine is continued to maintain the output of the engine, and then the output of the engine is reduced based on the change in the inputtable electric power.

3. The control method of a hybrid vehicle according to claim 1 or claim 2, wherein: If the charging rate of the battery exceeds the upper limit value, the output of the engine is stopped.

4. The control method of a hybrid vehicle according to claim 1 or claim 2, wherein: controlling the output of the engine based on a rotation speed command value and a torque command value, When the response to the rotation speed command value and the torque command value lags behind the delay time of the engine control system for a predetermined time or longer while the engine output is being reduced, the engine output is stopped.

5. A control system for a hybrid vehicle, comprising: Drive motor; A battery that supplies and receives electric power from the drive motor; a generator driven by the power generation engine and generating electricity in response to a power generation request accompanying an operation by a driver to charge 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, The charging rate of the battery is set so that the closer it is to a predetermined upper limit value, the lower the power that can be input to the battery. If the charging rate of the battery reaches the vicinity of the upper limit value due to the regenerative power received from the drive motor and the generated power received from the generator, and the input power becomes less than the sum of the regenerative power and the generated power, the control unit stops the fuel supply 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, The control unit stops the supply of fuel to the engine when the temperature of the catalyst is lower than or equal to a predetermined temperature for suppressing degradation of the catalyst when the power generation request is stopped. When the temperature of the catalyst exceeds the specified temperature when the power generation request is stopped, the fuel supply to the engine is continued to maintain the output of the engine, and then the output of the engine is reduced when the moving average of the current involved in the total exceeds a specified reference value or the negative electrode potential of the battery is lower than a specified reference potential.

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