Hybrid vehicle control method and hybrid vehicle control system

Abstract

Provided is a hybrid vehicle control method in which electric power is exchanged between a drive motor 1 and a battery 2, a generator 4 driven by a power generation engine 3 charges the battery 2, and exhaust gas exhausted from the engine 3 is treated by a catalyst, wherein 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 to stop the power generation of the generator 4, regenerative power is consumed by stopping fuel supply to the engine 3 and supplying power from the battery 2 to the generator 4 to cause the engine 3 to perform power running (motoring), and in a state in which the temperature of the catalyst is lower than an upper limit temperature at which catalyst deterioration can be minimized, the discharge amount of the battery 2 is increased commensurately as the temperature of the catalyst approaches the upper limit temperature or as the temperature of the catalyst rises faster.

Description

Hybrid vehicle control method and hybrid vehicle control system

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

[0002] JP2021-110268A discloses a vehicle equipped with a generator driven by a power-generating engine to generate electricity, a catalyst for treating exhaust gas discharged from the engine, a battery for storing the electricity generated by the generator and supplying the electricity to a motor, and a battery control unit that prohibits the generator from generating electricity when the charging rate of the battery is equal to or higher than a first charging rate threshold for suppressing overcharging. JP2021-110268A also discloses that when a discharge condition is met in which the charging rate of the battery exceeds a second charging rate threshold that is lower than the first charging rate threshold, the battery control unit increases the power supply from the battery to the motor compared to when the discharge condition is not met.

[0003] The battery's charging rate also increases when it receives regenerative power from the motor. If the battery receives regenerative power from the motor for a long period of time, it may reach the first charging rate threshold. In this case, to prevent overcharging, as described above, control is required to stop fuel supply to the engine and supply the battery's power to a generator to drive the engine (internal combustion engine) (powering operation), i.e., to discharge and consume the regenerative power by motoring. Meanwhile, catalysts deteriorate when exposed to a lean atmosphere when their temperature exceeds a predetermined upper limit. Therefore, stopping fuel supply to the engine when the catalyst temperature exceeds the upper limit may cause the catalyst to deteriorate.

[0004] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control method for a hybrid vehicle and a control system for a hybrid vehicle that suppresses catalyst deterioration.

[0005] According to one aspect of the present invention, there is provided a control method for a hybrid vehicle in which electric power is exchanged between a drive motor and a battery, a generator driven by a power-generating engine charges the battery, and exhaust gas from the engine is treated with a catalyst. In this control method, when the battery's charging rate exceeds a predetermined threshold due to regenerative power received from the drive motor, fuel supply to the engine is stopped to stop power generation by the generator, and power is supplied from the battery to the generator to power the engine, thereby consuming the regenerative power. Then, when the catalyst temperature is lower than the upper limit temperature at which catalyst degradation can be suppressed, the battery discharge rate is increased as the catalyst temperature approaches the upper limit temperature or as the rate of catalyst temperature rise increases.

[0006] FIG. 1 is a schematic diagram of a control system for a hybrid vehicle according to this embodiment. FIG. 2 is a diagram showing charge / discharge demand curves representing the charge demand and discharge demand for the battery in a coordinate space with axes representing the charge / discharge current for the battery and the battery's charging rate. FIG. 3 is a map showing the relationship between the catalyst temperature, the rate of increase in catalyst temperature, and the central charging rate set by the vehicle controller. FIG. 4 is a time chart showing the catalyst temperature, the discharge demand output by the vehicle controller, and the central charging rate set by the vehicle controller. FIG. 5 is a block diagram of the vehicle controller. FIG. 6 is a map included in a demand adjustment unit constituting the vehicle controller, which calculates the central charging rate (Z) of the battery based on a first central charging rate (Y) calculated by the charging request unit and a second central charging rate (X) calculated by the discharging request unit. FIG. 7 is a control flow diagram for the vehicle controller.

[0007] [Basic Configuration of the Present Embodiment] Fig. 1 is a schematic diagram of a control system for a hybrid vehicle according to the present embodiment. As shown in Fig. 1, the control system for a hybrid vehicle according to the present embodiment is composed of a drive motor 1, a battery 2, an engine 3, a generator 4, a catalyst system 5, and control units (a vehicle controller 7, an engine controller 8, and a motor controller 9).

[0008] The drive motor 1 is mechanically coupled to the drive wheels 12 via a reducer 10 and a drive shaft 11, and receives electric power from the battery 2 (and the generator 4) to drive the drive wheels 12. The drive motor 1 also generates regenerative electric power when decelerating the rotation of the drive wheels 12.

[0009] The battery 2 supplies electric power to the drive motor 1 and is charged with regenerated electric power generated by the drive motor 1 and electric power generated by the generator 4 .

[0010] The engine 3 (internal combustion engine) is, for example, a gasoline engine. The engine 3 is coupled to a generator 4 so as to be capable of transmitting power, and burns fuel (gasoline) to rotate the generator 4, thereby causing the generator 4 to generate electricity.

[0011] The generator 4 supplies the generated electric power to the battery 2 and the drive motor 1. The generator 4 may receive electric power from the battery 2 to power (motor) the engine 3 to which fuel supply has been stopped. This powering operation is used not only to consume excess regenerated electric power, but also to crank the engine 3 when it is started and to generate negative pressure for brake pedal assist.

[0012] The catalyst system 5 processes the exhaust gas emitted from the engine 3 to produce harmless gas, and releases the harmless gas to the outside via a muffler 6 .

[0013] The control units (vehicle controller 7, engine controller 8, motor controller 9) are composed of one or more microcomputers equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface). In the control units (vehicle controller 7, engine controller 8, motor controller 9), various controls are performed by the CPU executing programs stored in the ROM or RAM.

[0014] 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 .

[0015] The vehicle controller 7 outputs a discharge request to the motor controller 9 when the charging rate of the battery 2 is higher than a predetermined reference charging rate (center charging rate), and conversely outputs a charge request to the motor controller 9 when the charging rate is lower.

[0016] Furthermore, the vehicle controller 7 shifts the central charging rate to a lower charging rate than the reference charging rate (e.g., 55%) when executing catalyst degradation suppression control (described later), and shifts the central charging rate to a higher charging rate than the reference charging rate when executing pre-charge request control (described later).When the vehicle controller 7 determines that catalyst degradation suppression control and pre-charge request control (described later) are required simultaneously, the vehicle controller 7 sets the central charging rate to a charging rate that is compromised between the two controls, as described later.

[0017] When the charging rate of the battery 2 exceeds a predetermined threshold (for example, 80%]), the vehicle controller 7 outputs an engine stop command to the engine controller 8 and outputs a powering command to the motor controller 9 .

[0018] When the engine controller 8 receives an engine start command 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 based on the output required of the generator 4, and also controls the output of the engine 3 so that the operating point (rotation speed, torque) of the engine 3 becomes the optimal operating point (the point at which the output efficiency is maximized).

[0019] Furthermore, when the engine controller 8 receives an engine stop command from the vehicle controller 7, it stops the supply of fuel to the engine 3 and stops the driving of the engine 3 (the generation of electricity by the generator 4).

[0020] The engine controller 8 acquires information on the temperature of the catalyst (for example, titanium (Ti)) included in the catalyst system 5 and outputs this information to the vehicle controller 7 .

[0021] The motor controller 9 controls the drive motor 1 based on the torque command value and the discharge request (or charge request), and controls the generator 4 based on the discharge request (or charge request).

[0022] 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 reduces the output of the generator 4 accordingly.

[0023] Furthermore, when a charge 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.

[0024] Furthermore, when the motor controller 9 receives a powering command from the vehicle controller 7, it drives the generator 4 using power (discharge) from the battery 2, and powers (motors) the engine 3, the fuel supply of which has been stopped.

[0025] 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). These inverters may be understood as components separate from the motor controller 9.

[0026] 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 charge request) and outputs it to the drive motor 1. When the motor controller 9 receives a discharge request, the first inverter outputs AC power greater than the AC power determined by the torque command value to the drive motor 1, and when the motor controller 9 receives a charge request, the first inverter outputs AC power smaller than the AC power determined by the torque command value to the drive motor 1. Furthermore, when the drive motor 1 is generating regenerative power, the first inverter converts this into DC power to charge the battery 2.

[0027] The second inverter converts AC power generated by the generator 4 into DC power to charge the battery 2. When the motor controller 9 receives a powering operation command, the second inverter converts the DC power of the battery 2 into DC power and outputs it to the generator 4.

[0028] [Charge / Discharge Demand Curve] FIG. 2 is a diagram showing a charge / discharge demand curve that indicates a charge demand for the battery 2 and a discharge demand for the battery 2 in a coordinate space with axes representing the charge / discharge current for the battery 2 and the charging rate of the battery 2.

[0029] As shown in Figure 2, the charge / discharge demand curve has an inflection point at a predetermined central charging rate (reference charging rate), and as the charging rate decreases below the central charging rate, it monotonically increases in an upward convex shape, and as the charging rate increases above the central charging rate, it monotonically decreases in a downward convex shape. In the charge / discharge demand curve, the charge demand becomes zero when the charging rate is equal to or higher than the central charging rate, and the discharge demand becomes zero when the charging rate is equal to or lower than the central charging rate. In other words, when the charging rate is at the central charging rate, both the charge demand and the discharge demand become zero.

[0030] The charge request amount (current value) of the charge request monotonically increases along the charge / discharge request curve as the charging rate becomes lower than the central charging rate.

[0031] The discharge request amount (current value) of the discharge request increases monotonically along the charge / discharge request curve as the charging rate becomes higher than the central charging rate.

[0032] The vehicle controller 7 sets the charge / discharge request curve so that the initial value of the central charging rate is the reference charging rate (for example, 55%]).

[0033] On the other hand, when executing catalyst degradation suppression control (described later), the vehicle controller 7 shifts the central charging rate, for example, to a lower charging rate than the reference charging rate, thereby shifting the charge / discharge request curve toward a lower charging rate. Furthermore, when executing pre-charge request control (described later), the vehicle controller 7 shifts the central charging rate, for example, to a higher charging rate than the reference charging rate, thereby shifting the charge / discharge request curve toward a higher charging rate. Furthermore, when the vehicle controller 7 determines that catalyst degradation suppression control and pre-charge request control (described later) are required simultaneously, the vehicle controller 7 sets the central charging rate to a mediation between the two controls, as described later.

[0034] [Catalyst Degradation Suppression Control and Pre-Charge Requirement Control] FIG. 3 is a map showing the relationship between the catalyst temperature, the rate of catalyst temperature rise, and the central charging rate set by the vehicle controller 7. As shown in FIG.

[0035] The charging rate of the battery 2 increases due to the regenerated power received from the drive motor 1 and the generated power received from the generator 4. Receiving regenerated power for a long period of time, in particular, can exceed a predetermined threshold (e.g., 80%), resulting in an overcharge state and deterioration of the battery 2. Therefore, in this embodiment, when the threshold is exceeded, fuel supply to the engine 3 is stopped, power generation by the generator 4 is stopped, and power is supplied from the battery 2 to the generator 4, causing the engine 3 to operate (motor) without fuel supply, thereby consuming the regenerated power (reducing the charging rate of the battery 2). At this time, the catalyst is exposed to a lean atmosphere, and if the temperature of the catalyst exceeds a predetermined upper limit temperature (e.g., 700°C), catalyst deterioration may occur.

[0036] Therefore, in this embodiment, catalyst degradation suppression control is executed to suppress catalyst degradation by reducing the frequency at which the charging rate of the battery 2 exceeds a threshold value (e.g., 80%]) for motoring the engine 3 when the temperature of the catalyst exceeds an upper limit temperature (e.g., 700°C). In catalyst degradation suppression control, the central charging rate of the battery 2 is shifted to a lower charging rate side, thereby reducing the frequency at which the charging rate of the battery 2 exceeds the threshold value, thereby suppressing catalyst degradation.

[0037] In catalyst degradation suppression control, when the catalyst temperature exceeds a first reference temperature (e.g., 650°C) that is lower than the upper limit temperature (700°C), the central charging rate is set to a charging rate lower than the reference charging rate, and the higher the catalyst temperature becomes, the lower the central charging rate is shifted toward.

[0038] In addition, in catalyst degradation suppression control, even if the catalyst temperature is lower than the upper limit temperature, if the rate of temperature rise exceeds a predetermined rate, the central charging rate is set to a charging rate lower than the reference charging rate, and the faster the rate of rise becomes, the more the central charging rate is shifted toward the lower charging rate.

[0039] Therefore, in a coordinate space where the horizontal axis represents catalyst temperature and the vertical axis represents the rate of catalyst temperature rise, the central charge rate set by catalyst degradation suppression control can be represented by the equal central charge rate lines shown in Figure 3. In Figure 3, the same equal central charge rate line has the same central charge rate. Furthermore, the further the equal central charge rate line is from the origin, the lower the central charge rate becomes.

[0040] The equal-center-charge-rate line shown in Figure 3 can also be applied when the catalyst temperature is lower than the first reference temperature. However, except when pre-charge request control (described later) is also performed, if the center charge rate required by catalyst degradation suppression control is higher than the reference charge rate, catalyst degradation suppression control is not actually performed.

[0041] Furthermore, when the same central charging rate is applied, it is preferable to provide a hysteresis width (e.g., 20°C) for temperature by setting the trigger level (temperature at which the central charging rate is switched) when the catalyst temperature rises higher than the trigger level (temperature at which the central charging rate is switched) when the catalyst temperature falls. This makes it possible to set the central charging rate so that it does not switch frequently when the catalyst temperature repeatedly rises and falls, thereby reducing the burden on control.

[0042] In addition, in the catalyst degradation suppression control, it is also possible to limit the output of the generator 4 (the output of the engine 3) so that the temperature of the catalyst does not exceed the upper limit temperature.

[0043] 4 is a time chart of the catalyst temperature, the discharge request output by the vehicle controller 7, and the central charging rate set by the vehicle controller 7. Before time t0, the engine 3 starts, the generator 4 generates electricity, and exhaust gas is discharged into the catalyst system 5, causing the catalyst temperature (BED temperature) to increase. The central charging rate is set to the reference charging amount.

[0044] At time t1, the temperature of the catalyst reaches a first reference temperature (T ｃ１ ) (for example, 650° C.), the vehicle controller 7 reduces the central charging rate in accordance with the map of FIG.

[0045] The motor controller 9 increases the power (discharge amount) from the battery 2 to the drive motor 1 and reduces the output of the generator 4 .

[0046] The vehicle controller 7 shifts the central charging rate to a lower value as the catalyst temperature rises. Therefore, as the central charging rate decreases, the power supplied from the battery 2 to the drive motor 1 increases, and the output of the generator 4 decreases accordingly.

[0047] At time t2, when the catalyst temperature reaches its peak (e.g., 670°C), the central charging rate is also set to its lowest state. This reduces the frequency with which the charging rate of the battery 2 exceeds a threshold value (e.g., 80%.) After time t2, when the catalyst temperature begins to decrease, the vehicle controller 7 gradually returns the central charging rate to its original value.

[0048] At time t3, the temperature of the catalyst reaches, for example, a second reference temperature (T ｃ２ ) (for example, 630°C) and the central charging rate reaches the original reference charging amount, the vehicle controller 7 sets the central charging rate to the reference charging amount and stops the discharge request. By controlling in this way, the temperature of the catalyst is ｍａｘ ) (for example, 700 [°C]).

[0049] In the catalyst degradation suppression control, it is also preferable to perform control to increase the discharge amount of the battery 2 without changing the output of the generator 4. In this case, the frequency with which the charging rate of the battery 2 exceeds a threshold value (e.g., 80%]) decreases, so that the frequency with which fuel supply to the engine 3 is stopped and the engine 3 is motored when the catalyst temperature exceeds the upper limit temperature can be reduced, thereby suppressing catalyst degradation.

[0050] [Vehicle Controller 7] Figure 5 is a block diagram of the vehicle controller 7. This block diagram shows the case where the vehicle controller 7 performs the catalyst degradation suppression control and the pre-charge request control. The vehicle controller 7 includes a charge request unit 701, a discharge request unit 702, and a request adjustment unit 703.

[0051] The charge request unit 701 is a component that executes pre-charge request control. Map information is input to the charge request unit 701. The map information indicates the future driving state of the vehicle, for example, the topography (altitude and slope of the road surface) and traffic conditions (presence or absence of a highway) of the driving route from the current position of the vehicle to a predetermined distance (for example, 5 km or 10 km) ahead of the vehicle's destination.

[0052] The charge request unit 701 refers to map information and determines, for example, if the vehicle is currently traveling on flat ground but an uphill slope with a predetermined gradient begins 2 kilometers ahead and continues for a predetermined distance or more, that high-load operation will be performed, which consumes more power from the battery 2 than normal operation. Here, normal operation refers to, for example, a state in which the vehicle travels on a flat, general road at a normal speed (e.g., 60 km / h). High-load operation refers to a state in which the power supply from the generator 4 to the drive motor 1 is kept approximately constant and the power supply from the battery 2 to the drive motor 1 is significantly increased.

[0053] The charge request unit 701 calculates the amount of work required to climb the detected uphill slope, and calculates a first central charging rate (for example, the minimum charging rate that is in principle acceptable for pre-charge request control) as the amount of charge of the battery 2 that can cover the amount of work based on the calculated amount of work, and outputs the first central charging rate to the request adjustment unit 703. This eliminates the need to increase the output of the generator 4 during high-load operation, thereby improving the sound and vibration performance of the vehicle.

[0054] Furthermore, even if the vehicle is currently traveling on an ordinary road but determines that it will enter an expressway two kilometers away and will drive at high speed (high load), the charging request unit 701 calculates the workload for high speed driving, and based on that workload, calculates a first central charging rate as the charge amount for battery 2 that can cover that workload, and outputs the calculated first central charging rate to the request adjustment unit 703.

[0055] Furthermore, the first central charging rate may be corrected based on the road gradient, altitude, and vehicle speed input to the charging request unit 701. The charging request unit 701 may correct the first central charging rate so that the steeper the gradient, the faster the vehicle speed, and the higher the altitude, respectively.

[0056] The discharge request unit 702 is a component that executes catalyst degradation suppression control. When the catalyst temperature is input to the discharge request unit 702, the discharge request unit 702 calculates the rate of rise in the catalyst temperature. Then, the discharge request unit 702 calculates a second center charging rate (for example, the maximum charging rate that the catalyst degradation suppression control can generally allow) based on the map shown in FIG. 3 and outputs the calculated value to the request adjustment unit 703.

[0057] In addition, the discharge request unit 702 can input the map information and set the second central charging rate to an even lower value if, for example, it is predicted that the catalyst temperature will reach the first reference temperature 2 kilometers ahead of the vehicle, a downhill slope with a predetermined gradient will begin 2 kilometers ahead, and the downhill slope is then predicted to continue for more than a predetermined distance.

[0058] The request adjustment unit 703 compares the reference charging rate, the first central charging rate output from the charge request unit 701, and the second central charging rate output from the discharge request unit 702 as described below to calculate the final central charging rate.

[0059] [Map of request adjustment unit 703] Figure 6 is a map held by the request adjustment unit 703 that constitutes the vehicle controller 7, and is a map that the vehicle controller 7 uses to calculate a discharge request and a central charging rate (Z) that is used as a criterion for determining the request, based on the first central charging rate (Y) calculated by the charge request unit 701 and the second central charging rate (X) calculated by the discharge request unit 702.

[0060] The vertical axis of Fig. 6 is the first central charging rate (Y), which corresponds to the lower limit of the charging rate of the battery 2 requested by the charging request unit 701. The horizontal axis of Fig. 7 is the second central charging rate (X), which corresponds to the upper limit of the charging rate of the battery 2 requested by the discharging request unit 702. The reference charging rate is, for example, X = X １ , Y=Y １ (X １ = Y １ = 55[%]).

[0061] If the first central charging rate (Y) and the second central charging rate (X) coincide (if they overlap the Y=X line shown in Figure 6), the request adjustment unit 703 sets the central charging rate (Z) to the first central charging rate (Y) or the second central charging rate (X).

[0062] More specifically, when the first central charging rate (Y) and the second central charging rate (X) are the same value and higher than the reference charging rate, the request adjustment unit 703 does not follow the request of the discharge request unit 702 but sets the central charging rate (Z) in accordance with the request from the charge request unit 701. When the first central charging rate (Y) and the second central charging rate (X) are the same value and lower than the reference charging rate, the request adjustment unit 703 does not follow the request of the charge request unit 701 but sets the central charging rate (Z) in accordance with the request from the discharge request unit 702. When the first central charging rate (Y) and the second central charging rate (X) match the reference charging rate, the request adjustment unit 703 does not follow the request of the charge request unit 701 or the discharge request unit 702 but sets the central charging rate (Z) to the reference charging rate.

[0063] When the first central charging rate (Y) is lower than the second central charging rate (X), and when the first central charging rate (Y) is lower than the reference charging rate and the second central charging rate (X) is higher than the reference charging rate (area A in FIG. 6), the request adjuster 703 sets the central charging rate (Z) to the reference charging rate, i.e., Z=X １ = Y １ Set to.

[0064] 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 discharging request unit 702, and therefore satisfies the charging rates requested by both. Therefore, the request adjustment unit 703 sets the central charging rate to the reference charging rate.

[0065] When the first central charging rate (Y) is lower than the second central charging rate (X) and the first central charging rate (Y) and the second central charging rate (X) are higher than the reference charging rates (area B in FIG. 6 ), the request adjuster 703 sets the central charging rate (Z) to the first central charging rate (Y), i.e., sets Z = Y. In this case, catalyst degradation request control is not actually being performed, so the request adjuster 703 sets the central charging rate (Z) to the first central charging rate (Y).

[0066] When the first central charging rate (Y) is lower than the second central charging rate (X) and the first central charging rate (Y) and the second central charging rate (X) are lower than the reference charging rate (area C in FIG. 6 ), the request adjuster 703 sets the central charging rate (Z) to the second central charging rate (X), i.e., sets Z = X. In this case, since the pre-charging request control is not actually performed, the request adjuster 703 sets the central charging rate (Z) to the second central charging rate (X).

[0067] The request adjusting unit 703 adjusts the first central charging rate (Y) to a predetermined lower limit (Y ｍｉｎ , for example, 46% (area D in FIG. 6), the central charging rate (Z) is set to the second central charging rate (X), i.e., Z=Y. When the first central charging rate (Y) requested by the charge request unit 701 is higher than the second central charging rate (X) requested by the discharge request unit 702, it becomes somewhat complicated to determine which one to select preferentially. However, when the first central dielectric constant (Y) is lower than a predetermined lower limit (Y ｍｉｎ ), it can also be determined that the pre-charge request control is not actually being performed. At this time, the second central charging rate (X) is also a value lower than the predetermined charging rate (X<X ２ = Y ｍｉｎ ), which is a strong discharge request for catalyst deterioration request control. Therefore, the request adjustment unit 703 determines that there is a strong discharge request from the discharge request unit 702 and sets the central charging rate (Z) to the first central charging rate (Y).

[0068] The request adjuster 703 adjusts the first central charging rate (Y) to the lower limit (Y) when the first central charging rate (Y) is higher than the second central charging rate (X). ｍｉｎ ) is higher than a predetermined upper limit value (Y ｍａｘ , for example, 69% (area E in FIG. 6), the central charging rate (Z) is set to the first central charging rate (Y), that is, Z=Y.

[0069] In this case, the request adjustment unit 703 determines that a strong charging request is being made as pre-charging request control and that it should be executed in priority over catalyst degradation suppression control, and sets the central charging rate (Z) to the first central charging rate (Y).

[0070] The request adjuster 703 adjusts the first central charging rate (Y) to the lower limit (Y) when the first central charging rate (Y) is higher than the second central charging rate (X). ｍｉｎ ) and upper limit (Y ｍａｘ ), and when the second central charging rate (X) is lower than X2=Ymin (area F in FIG. 6), the first central charging rate (Y) is lower than the upper limit value (Y ｍａｘ ), the central charging rate (Z) is set to a value closer to the first central charging rate (Y), and when the first central charging rate (Y) is closer to the lower limit value (Y ｍｉｎ ), the central charging rate (Z) is set to a value closer to the second central charging rate (X). Here, X2 is the value of X obtained by substituting Ymin for Y in the relational equation Y=X (FIG. 6), which is expressed as a line in a coordinate space with the Y coordinate of the first central charging rate (Y) and the X coordinate of the second central charging rate (X), and is the same value as Ymin.

[0071] In this case, the central charging rate (Z) is a sum of the first central charging rate (Y), the second central charging rate (X), and the lower limit (Y ｍｉｎ ), upper limit (Y ｍａｘ ) can be expressed by the following equation (1).

[0072] In the above case, the request adjustment unit 703 does not perform control that prioritizes only one of the pre-charge request control and the catalyst degradation control, but rather aims to achieve both the pre-charge request control and the catalyst degradation control by harmonizing the first central charging rate (Y) and the second central charging rate (X) and setting a central charging rate (Z) that is not disadvantageous to either the pre-charge request control or the catalyst degradation control.

[0073] The request adjuster 703 adjusts the first central charging rate (Y) to the lower limit (Y) when the first central charging rate (Y) is higher than the second central charging rate (X). ｍｉｎ ) and upper limit (Y ｍａｘ), and when the second central charging rate (X) is equal to or greater than X2=Ymin and lower than X3=Ymax (area G in FIG. 6), the central charging rate (Z) is set to the first central charging rate (Y), i.e., Z=Y. Here, X3 is the value of X obtained by substituting Ymax for Y in the relational equation Y=X (FIG. 6), which is expressed as a line in the coordinate space with the Y coordinate of the first central charging rate (Y) and the X coordinate of the second central charging rate (X), and is the same value as Ymax.

[0074] In this case, the request adjustment unit 703 determines that a strong charging request is being made as pre-charging request control and that it should be executed in priority over catalyst degradation suppression control, and sets the central charging rate (Z) to the first central charging rate (Y).

[0075] [Control Flow of Vehicle Controller 7] Figure 7 is a control flow diagram of the vehicle controller 7. In step S1, the vehicle controller 7 (discharge request unit 702) acquires information on the catalyst temperature (BED temperature). In addition, the vehicle controller 7 (charge request unit 701) acquires map information related to the route that the vehicle will pass immediately before, from information on the route to the vehicle's destination.

[0076] In step S2, the vehicle controller 7 (discharge request unit 702) calculates the rate of rise of the catalyst temperature based on the catalyst temperature acquired last time and the catalyst temperature acquired this time, and calculates a second central charging rate based on the temperature information acquired this time, the calculated rate of rise of the catalyst temperature, and the map shown in Figure 3.

[0077] In step S3, the vehicle controller 7 (charge request unit 701) calculates the amount of work (energy consumption) of the vehicle based on the map information.

[0078] In step S4, the vehicle controller 7 (charge request unit 701) calculates a first central charging rate based on the workload.

[0079] In step S5, the vehicle controller 7 (charge request unit 701) calculates the central charging rate by referring to the map shown in FIG. 6 for the first central charging rate and the second central charging rate.

[0080] The vehicle controller 7 outputs a discharge request to the motor controller 9 if the charging rate of the battery 2 is higher than the calculated central charging rate, and conversely outputs a charge request to the motor controller 9 if the charging rate is lower.

[0081] Effects of the Present Embodiment According to the control method for a hybrid vehicle of the present embodiment, electric power is exchanged between the drive motor 1 and the battery 2, the generator 4 driven by the power-generating engine 3 charges the battery 2, and exhaust gas emitted from the engine 3 is treated by a catalyst (catalyst system 5). In this control method, when the charging rate of the battery 2 exceeds a predetermined threshold (e.g., 80%) due to regenerative power received from the drive motor 1, the supply of fuel to the engine 3 is stopped to stop the power generation of the generator 4, and electric power is supplied from the battery 2 to the generator 4 to power the engine 3, thereby consuming the regenerative power. In a state where the temperature of the catalyst (catalyst included in the catalyst system 5) is lower than an upper limit temperature (e.g., 700°C) at which catalyst degradation can be suppressed, the discharge amount of the battery 2 is increased as the temperature of the catalyst (catalyst included in the catalyst system 5) approaches the upper limit temperature (e.g., 700°C) or as the rate of rise in the temperature of the catalyst (catalyst included in the catalyst system 5) becomes faster.

[0082] The above method reduces the frequency of powering (motoring) the engine 3 when the catalyst temperature exceeds the upper limit temperature (e.g., 700°C), thereby suppressing catalyst deterioration. Furthermore, because catalyst deterioration can be suppressed, the amount of catalyst (precious metal) can be reduced.

[0083] In this embodiment, in a coordinate space having axes representing the charge / discharge current for battery 2 and the charging rate, the charging rate is controlled according to a charge / discharge requirement curve ( FIG. 2 ) that includes a central charging rate, which has as its initial value a reference charging rate at which the charging demand for battery 2 and the discharging demand for battery 2 are zero, and which represents a trajectory in which the charging demand becomes higher as the charging rate becomes lower than the central charging rate, and the discharging demand becomes higher as the charging rate becomes higher than the central charging rate. In this case, the central charging rate is shifted toward a lower charging rate than the reference charging rate as discharge amount increase control (catalyst degradation suppression control) that increases the amount of discharge of battery 2, thereby shifting the charge / discharge requirement curve toward a lower charging rate.

[0084] By the above method, it is possible to request discharge after lowering the central charging rate in a simple manner.

[0085] In this embodiment, map information relating to the route that the vehicle will take immediately before is obtained from the information on the route to the vehicle's destination, and when it is predicted that the vehicle will be operating under high load, consuming more power from battery 2 than in normal operation, by referring to the map information, pre-charge request control is executed to shift the central charging rate to the higher charging rate side.If it is determined from the map information that the vehicle will be climbing an uphill slope of more than a predetermined distance, priority is given to pre-charge request control, and if it is determined from the map information that the vehicle will be descending a downhill slope of more than a predetermined distance, priority is given to discharge amount increase control (catalyst deterioration suppression control).

[0086] By using the above method, it is possible to selectively execute either pre-charge request control or discharge amount increase control (catalyst degradation suppression control) depending on the conditions of the road on which the vehicle is traveling.

[0087] In this embodiment, map information relating to the route that the vehicle will travel immediately before is acquired from information on the route to the destination of the vehicle, and when it is predicted that the vehicle will be driven under high load with the map information being used to consume more power from the battery 2 than in normal driving, pre-charge request control is executed to shift the central charging rate (Z) to a higher charging rate. The workload of the high load driving is calculated based on the map information, and the central charging rate required by the pre-charge request control is calculated based on the workload as a first central charging rate (Y), and the central charging rate required by the discharge amount increase control (catalyst degradation suppression control) is calculated based on the temperature or rise rate of the catalyst as a second central charging rate (X), and when the first central charging rate (Y) is higher than the second central charging rate (X), the first central charging rate (Y) is set to a predetermined lower limit value (Y ｍｉｎ ), the central charging rate (Z) is set to the second central charging rate (X), and when the first central charging rate (Y) is higher than the second central charging rate (X), the first central charging rate (Y) is set to the lower limit (Y ｍｉｎ ) is higher than a predetermined upper limit value (Y ｍａｘ ), the central charging rate (Z) is set to the first central charging rate (Y), and when the first central charging rate (Y) is higher than the second central charging rate (X) and the first central charging rate (Y) is lower than the lower limit (Yｍｉｎ ) and upper limit (Y ｍａｘ ) when the first central charging rate (Y) is a value between the upper limit value (Y ｍａｘ ), the central charging rate (Z) is set to a value closer to the first central charging rate (Y), and when the first central charging rate (Y) is closer to the lower limit value (Y ｍｉｎ ), the central charging rate (Z) is set to a value closer to the second central charging rate (X).

[0088] With the above method, the higher the first central charging rate (Y) in the pre-charging request control, the higher the priority, and the lower the second central charging rate (X) in the catalyst degradation request control, the higher the priority. Therefore, the priority of the pre-charging request control and the catalyst degradation suppression control can be determined depending on the road conditions, and the pre-charging request control and the catalyst degradation suppression control can be appropriately executed. Furthermore, when the catalyst degradation suppression control is executed, the charging rate of the battery 2 is lowered in advance, so that the number of times the engine 3 motors when the catalyst temperature is below the upper limit temperature can be reduced.

[0089] In this embodiment, when the first central charging rate (Y) and the second central charging rate (X) are the same, the central charging rate (Z) is set to the first central charging rate (Y) or the second central charging rate (X). When the first central charging rate (Y) is lower than the second central charging rate (X) and the first central charging rate (Y) is lower than the reference charging rate (Y), the central charging rate (Z) is set to the reference charging rate (Y). １ , for example, 55[%]), and the second central charging rate (X) is lower than the reference charging rate (X １ = Y １ ), the central charging rate (Z) is set to the reference charging rate; if the first central charging rate (Y) is lower than the second central charging rate (X) and the first central charging rate (Y) and the second central charging rate (X) are higher than the reference charging rates, the central charging rate (Z) is set to the first central charging rate (Y); if the first central charging rate (Y) is lower than the second central charging rate (X) and the first central charging rate (Y) and the second central charging rate (X) are lower than the reference charging rates, the central charging rate (Z) is set to the second central charging rate (X).

[0090] With the above method, the higher the first central charging rate (Y) in the pre-charging request control, the higher the priority, and the lower the second central charging rate (X) in the catalyst degradation request control, the higher the priority. Therefore, the priority of the pre-charging request control and the catalyst degradation suppression control can be determined depending on the road conditions, and the pre-charging request control and the catalyst degradation suppression control can be appropriately executed. Furthermore, when the catalyst degradation suppression control is executed, the charging rate of the battery 2 is lowered in advance, so that the number of times the engine 3 motors when the catalyst temperature is below the upper limit temperature can be reduced.

[0091] In this embodiment, the output of the engine 3 that drives the generator 4 is reduced by the amount of increase in the discharge amount of the battery 2 .

[0092] By using the above method, the output of the engine 3 that drives the generator 4 is reduced, thereby suppressing the temperature rise of the catalyst, and thereby suppressing the deterioration of the catalyst.

[0093] The hybrid vehicle control system of this embodiment includes a drive motor 1, a battery 2 that exchanges power with the drive motor 1, a generator 4 that generates power by being driven by a power-generating engine 3 to charge the battery 2, a catalyst (catalyst system 5) that treats exhaust gases discharged from the engine 3, and control units (vehicle controller 7, engine controller 8, motor controller 9) that control the battery 2, the engine 3, and the generator 4. When the charging rate of the battery 2 exceeds a predetermined threshold (for example, 80%) due to regenerative power received from the drive motor 1, the control units (vehicle controller 7, engine controller 8, motor controller 9) In a hybrid vehicle system in which regenerative power is consumed by stopping the supply of fuel to the engine 3 to stop the power generation of the generator 4 and supplying power from the battery 2 to the generator 4 to power the engine 3, the control unit (vehicle controller 7, engine controller 8, motor controller 9) increases the discharge amount of the battery 2 as the temperature of the catalyst (catalyst included in the catalyst system 5) approaches the upper limit temperature (e.g., 700°C) or the rate of rise in the temperature of the catalyst (catalyst included in the catalyst system 5) becomes faster when the temperature of the catalyst (catalyst included in the catalyst system 5) is lower than the upper limit temperature (e.g., 700°C) at which catalyst deterioration can be suppressed.

[0094] The above configuration reduces the frequency of powering (motoring) the engine 3 when the catalyst temperature exceeds the upper limit temperature (e.g., 700°C), thereby suppressing catalyst deterioration. Furthermore, because catalyst deterioration can be suppressed, the amount of catalyst (precious metal) can be reduced.

[0095] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate.

Claims

1. In a control method for a hybrid vehicle that transfers electric power between a drive motor and a battery, and in which a generator driven by a power generation engine charges the battery and exhaust gas discharged from the engine is processed by a catalyst, when the charge rate of the battery exceeds a predetermined threshold due to regenerative power received from the drive motor, fuel supply to the engine is stopped and power generation of the generator is stopped, and the regenerative power is consumed by supplying power from the battery to the generator to power drive the engine, A control method for a hybrid vehicle that increases the discharge amount of the battery as the rate of increase in the temperature of the catalyst increases in a state where the temperature of the catalyst is lower than the upper limit temperature at which deterioration of the catalyst can be suppressed.

2. In a coordinate space with the charge / discharge current to the battery and the charge rate as axes, including a central charge rate with a reference charge rate at which the charge demand and the discharge demand for the battery become zero as an initial value, the charge demand increases as the charge rate becomes lower than the central charge rate, and the discharge demand increases as the charge rate becomes higher than the central charge rate. When controlling the charge rate according to a charge / discharge demand curve representing a locus, The control method for a hybrid vehicle according to claim 1, wherein the charge / discharge demand curve is shifted to the low charge rate side by shifting the central charge rate to the low charge rate side with respect to the reference charge rate as a discharge amount increase control for increasing the discharge amount of the battery.

3. When acquiring map information related to the driving route immediately before the vehicle passes in the driving route information to the destination of the vehicle, and when it is predicted that the vehicle will perform a high load operation that consumes more electric power of the battery than normal driving with reference to the map information, and performing pre-charge demand control for shifting the central charge rate to the high charge rate side, When it is determined from the map information that the vehicle climbs an uphill slope of a predetermined distance or more, the pre-charge demand control is prioritized, The control method for a hybrid vehicle according to claim 2, wherein when it is determined from the map information that the vehicle descends a downhill slope of a predetermined distance or more, the discharge amount increase control is prioritized.

4. When acquiring map information related to the driving route immediately before the vehicle passes in the information on the driving route to the destination of the vehicle, and executing pre-charging request control to shift the center charge rate to the high charge rate side when it is predicted that a high-load operation that consumes more power of the battery than the normal operation of the vehicle will be performed with reference to the map information, calculate the workload of the high-load operation based on the map information, and calculate the center charge rate required by the pre-charging request control based on the workload as a first center charge rate, calculate the center charge rate required by the discharge amount increase control based on the rising speed as a second center charge rate, when the first center charge rate is higher than the second center charge rate and the first center charge rate is lower than a predetermined lower limit value, set the center charge rate to the second center charge rate, when the first center charge rate is higher than the second center charge rate and the first center charge rate is higher than a predetermined upper limit value which is higher than the lower limit value, set the center charge rate to the first center charge rate, when the first center charge rate is higher than the second center charge rate and the first center charge rate is between the lower limit value and the upper limit value, set the center charge rate to a value closer to the first center charge rate as the first center charge rate approaches the upper limit value, and set the center charge rate to a value closer to the second center charge rate as the first center charge rate approaches the lower limit value. The control method of the hybrid vehicle according to claim 2.

5. when the first center charge rate and the second center charge rate match, set the center charge rate to the first center charge rate or the second center charge rate, when the first center charge rate is lower than the second center charge rate, the first center charge rate is lower than the reference charge rate, and the second center charge rate is higher than the reference charge rate, set the center charge rate to the reference charge rate, when the first center charge rate is lower than the second center charge rate and both the first center charge rate and the second center charge rate are higher than the reference charge rate, set the center charge rate to the first center charge rate, when the first center charge rate is lower than the second center charge rate and both the first center charge rate and the second center charge rate are lower than the reference charge rate, set the center charge rate to the second center charge rate. The control method of the hybrid vehicle according to claim 4.

6. The control method for a hybrid vehicle according to claim 1, wherein the output of the engine that drives the generator is decreased by an increase in the discharge amount of the battery.

7. A drive motor, A battery that exchanges electric power with 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 discharged from the engine, A control unit that controls the battery, the engine, and the generator, In the control system for a hybrid vehicle, when the charging rate of the battery exceeds a predetermined threshold due to regenerative power received from the drive motor, the control unit stops fuel supply to the engine, stops power generation of the generator, and supplies power from the battery to the generator to drive the engine in a power running mode to consume the regenerative power. The control system for a hybrid vehicle, wherein the control unit increases the discharge amount of the battery as the rising speed of the temperature of the catalyst becomes faster in a state where the temperature of the catalyst is lower than the upper limit temperature at which deterioration of the catalyst can be suppressed.