Control method for hybrid vehicles, and control system for hybrid vehicles

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

[Technical Field]

[0001] This invention relates to a control method for hybrid vehicles and a control system for hybrid vehicles. [Background technology]

[0002] JP2021-110268A discloses a system comprising: a generator driven by an engine for power generation; a catalyst for treating exhaust gases discharged from the engine; a battery that stores the electricity generated by the generator and supplies power to a motor; and a battery control unit that prohibits power generation by the generator when the battery's charge level exceeds a first charge level threshold for suppressing overcharging. Furthermore, JP2021-110268A states that when the battery control unit meets a discharge condition where the battery's charge level exceeds a second charge level threshold lower than the first charge level threshold, it increases the power supply from the battery to the motor compared to when the discharge condition is not met. [Overview of the project]

[0003] Incidentally, the battery's charge level also increases when it receives regenerative power from the motor. And, if the battery receives regenerative power from the motor for an extended period, it may reach the first charge level threshold. In this case, as described above, to prevent overcharging, it becomes necessary to stop the fuel supply to the engine and supply battery power to the generator to drive the engine (internal combustion engine) (motorization), that is, to discharge the battery and consume the regenerative power by performing motoring. On the other hand, catalysts deteriorate when exposed to a lean atmosphere at temperatures exceeding a predetermined upper limit. Therefore, if the fuel supply to the engine is stopped when the catalyst temperature exceeds the upper limit, the catalyst may deteriorate.

[0004] Therefore, the present invention aims to provide a control method for a hybrid vehicle that suppresses catalyst degradation, and a control system for a hybrid vehicle.

[0005] According to one aspect of the present invention, this is a control method for a hybrid vehicle in which power is exchanged between a drive motor and a battery, a generator driven by an engine charges the battery, and exhaust gas emitted from the engine is treated by a catalyst. In this control method, when the battery charge rate exceeds a predetermined threshold due to regenerative power received from the drive motor, the fuel supply to the engine is stopped and the generator stops generating power, and power is supplied from the battery to the generator to operate the engine and consume the regenerative power. Furthermore, when the temperature of the catalyst is lower than the upper limit temperature at which catalyst degradation can be suppressed, the amount of battery discharge is increased as the temperature of the catalyst approaches the upper limit temperature, or as the rate of increase in the temperature of the catalyst increases. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic diagram of the control system of the hybrid vehicle according to this embodiment. [Figure 2] Figure 2 shows charge and discharge demand curves representing the charge and discharge demands for a battery, in a coordinate space with the charge / discharge current and battery charge level as axes. [Figure 3] Figure 3 is a map showing the relationship between the catalyst temperature, the rate at which the catalyst temperature rises, and the central charge level set by the vehicle controller. [Figure 4] Figure 4 is a time chart showing the catalyst temperature, the discharge request output by the vehicle controller, and the center charge level set by the vehicle controller. [Figure 5] Figure 5 is a block diagram of the vehicle controller. [Figure 6] Figure 6 shows a map of the request adjustment unit that constitutes the vehicle controller, which calculates the central charge rate (Z) of the battery based on the first central charge rate (Y) calculated by the charge request unit and the second central charge rate (X) calculated by the discharge request unit. [Figure 7] Figure 7 is a control flow diagram of the vehicle controller. [Modes for carrying out the invention]

[0007] [Basic Configuration of this Embodiment] FIG. 1 is a schematic diagram of a control system for a hybrid vehicle according to this embodiment. Figure 1 As shown in the figure, the control system for a hybrid vehicle according to this embodiment includes a drive motor 1, a battery 2, an engine 3, a generator 4, a catalyst system 5, a control unit (vehicle controller 7, engine controller 8, motor controller 9), etc.

[0008] The drive motor 1 is mechanically coupled to the drive wheels 12 via a reduction gear 10 and a drive shaft 11, and drives the drive wheels 12 by receiving electric power from the battery 2 (and the generator 4). Also, when the drive motor 1 decelerates the rotation of the drive wheels 12, it generates regenerative electric power.

[0009] The battery 2 supplies electric power to the drive motor 1 and also charges the regenerative electric power generated by the drive motor 1 and the 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 the generator 4 so as to be power-transmittable, and generates electric power for the generator 4 by burning fuel (gasoline) and rotating.

[0011] The generator 4 supplies the generated electric power to the battery 2 and the drive motor 1. Note that the generator 4 may power-run (motorize) the engine 3 whose fuel supply has been stopped by receiving electric power from the battery 2. This power-running is used not only for the purpose of consuming excess regenerative electric power, but also for cranking the engine 3 at the start of the engine 3 and generating negative pressure for brake pedal assist.

[0012] The catalyst system 5 processes the exhaust gas exhausted from the engine 3 so as to become harmless gas, and discharges the harmless gas to the outside through a muffler 6.

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

[0014] Based on the accelerator opening indicated by the accelerator pedal 13, the vehicle controller 7 outputs a torque command value to the motor controller 9.

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

[0016] Furthermore, when the vehicle controller 7 executes the catalyst deterioration suppression control described later, it shifts the central charge rate to a lower charge rate side than the reference charge rate (for example, 55 [%]), and when it executes the pre-charge request control described later, it shifts the central charge rate to a higher charge rate side than the reference charge rate. And when the vehicle controller 7 determines that the catalyst deterioration suppression control and the pre-charge request control described later are both necessary, it sets the central charge rate to a charge rate mediated between the two controls as described later.

[0017] When the charge 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 a power running 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 by the generator 4, but the engine controller 8 controls the output of the engine 3 so that the operating point (rotational speed, torque) of the engine 3 becomes the optimal operating point (the point where the output efficiency is maximized).

[0019] Furthermore, when the engine controller 8 receives an engine stop command from the vehicle controller 7, it stops supplying fuel to the engine 3 and stops the engine 3 from operating (generating power with the generator 4).

[0020] The engine controller 8 acquires information on the temperature of the catalyst (e.g., titanium (Ti)) included in the catalytic converter 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 the motor controller 9 receives a discharge request from the vehicle controller 7, it increases the discharge rate from the battery 2 and reduces the output of the generator 4 accordingly.

[0023] Furthermore, when the motor controller 9 receives a charge request from the vehicle controller 7, it reduces the discharge rate from the battery 2 and increases the output of the generator 4 accordingly.

[0024] Furthermore, when the motor controller 9 receives a power operation command from the vehicle controller 7, it uses the power (discharge) from the battery 2 to drive the generator 4 and power the engine 3, which has had its fuel supply stopped, to motorize it.

[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 a separate configuration 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 to the drive motor 1 that is greater than the AC power determined by the torque command value, and when a charge request is received, it outputs AC power to the drive motor 1 that is less than the AC power determined by the torque command value. In addition, if the drive motor 1 is generating regenerative power, the first inverter converts this into DC power and charges the battery 2.

[0027] The second inverter converts the AC power generated by the generator 4 into DC power to charge the battery 2. Furthermore, when the motor controller 9 receives a power operation command, the second inverter converts the DC power of the battery 2 into DC power. AC power It is converted and output to generator 4.

[0028] [Charge / discharge demand curve] Figure 2 shows charge and discharge demand curves representing the charge and discharge demands for battery 2 in a coordinate space with the charge / discharge current and the charge level of battery 2 as axes.

[0029] As shown in Figure 2, the charge / discharge demand curve has an inflection point at a predetermined central charge level (reference charge level), and the curve monotonically increases with an upward convex shape as the charge level decreases below the central charge level, and monotonically decreases with a downward convex shape as the charge level increases above the central charge level. In the charge / discharge demand curve, the charge demand becomes zero when the charge level is above the central charge level, and the discharge demand becomes zero when the charge level is below the central charge level. That is, both the charge demand and the discharge demand are zero when the charge level is at the central charge level.

[0030] The amount of charge required (current value) for a charge request increases monotonically according to the charge / discharge request curve as the charge rate falls below the central charge rate.

[0031] The discharge requirement (current value) increases monotonically according to the charge / discharge requirement curve as the charge rate increases above the central charge rate.

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

[0033] On the other hand, when the vehicle controller 7 performs the catalyst degradation suppression control described later, it shifts the charge / discharge request curve to the lower charge rate side by shifting the central charge rate to, for example, a lower charge rate than the reference charge rate. Also, when the vehicle controller 7 performs the pre-charge request control described later, it shifts the charge / discharge request curve to the higher charge rate side by shifting the central charge rate to, for example, a higher charge rate than the reference charge rate. Furthermore, if the vehicle controller 7 determines that both the catalyst degradation suppression control and the pre-charge request control described later are necessary at the same time, it sets the central charge rate to a compromise between the two controls as described later.

[0034] [Catalyst degradation suppression control and pre-charge request control] Figure 3 is a map showing the relationship between the catalyst temperature, the rate at which the catalyst temperature rises, and the central charge level set by the vehicle controller 7.

[0035] The charge level of battery 2 increases due to regenerative power received from the drive motor 1 and generated power received from the generator 4. In particular, receiving regenerative power for a long period of time can cause it to exceed a predetermined threshold (e.g., 80%) and become overcharged, potentially degrading battery 2. Therefore, in this embodiment as well, when this threshold is exceeded, the fuel supply to the engine 3 is stopped, the generator 4 stops generating power, and power is supplied from battery 2 to the generator 4 to stop the fuel supply. SupplyThe system executes a control mechanism that consumes regenerative power (reducing the charge level of battery 2) by motorizing the stopped engine 3. 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 degradation may occur.

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

[0037] In catalyst degradation suppression control, when the catalyst temperature exceeds a first reference temperature (e.g., 650°C) which is lower than the upper limit temperature (700°C), the central charge rate is set to a charge rate lower than the reference charge rate, and as the catalyst temperature rises further, the central charge rate is shifted to the lower charge rate side.

[0038] Furthermore, in catalyst degradation suppression control, even if the catalyst temperature is below the upper limit temperature, if the rate of temperature rise exceeds a predetermined rate, the central charge level is set to a charge level lower than the reference charge level, and the faster the rate of rise becomes, the further the central charge level is shifted towards the lower charge level.

[0039] Therefore, if the horizontal axis represents the catalyst temperature and the vertical axis represents the rate of increase in catalyst temperature, the central charge rate set by catalyst degradation suppression control can be represented by the equicentral charge rate lines shown in Figure 3 in coordinate space. In Figure 3, the same equicentral charge rate is present on the same equicentral charge rate line. Furthermore, the central charge rate decreases as the equicentral charge rate line moves away from the origin.

[0040] The equicentral charge rate line shown in Figure 3 can also be applied when the catalyst temperature is lower than the first reference temperature. However, unless it is performed in combination with the pre-charge request control described later, if the central charge rate required for catalyst degradation suppression control is higher than the reference charge rate, the catalyst degradation suppression control will not be effectively performed.

[0041] Furthermore, when applying the same central charge rate, it is preferable to set the trigger level when the catalyst temperature rises (the temperature at which the central charge rate is switched) to be higher than the trigger level when the temperature falls (the temperature at which the central charge rate is switched), thereby providing a hysteresis range (e.g., 20°C) with respect to temperature. This allows the central charge rate to be set so that it does not switch frequently when the catalyst temperature repeatedly rises and falls, thereby reducing the control burden.

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

[0043] Figure 4 is a time chart showing the catalyst temperature, the discharge request output by the vehicle controller 7, and the central charge level set by the vehicle controller 7. Before time t0, the engine 3 starts up, generating electricity with the generator 4 and releasing exhaust gas into the catalyst system 5, causing the catalyst temperature (BED temperature) to increase. The central charge level is set to the standard charge level.

[0044] At time t1, the temperature of the catalyst is the first reference temperature (T c1 When the temperature reaches (for example, 650°C), the vehicle controller 7 reduces the central charge level according to the map in Figure 3, thereby outputting a discharge request to the motor controller 9.

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

[0046] The vehicle controller 7 shifts the central charge level to a lower charge level as the catalyst temperature rises. Therefore, as the central charge level 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 charge level is also set to its lowest state. This reduces the frequency with which the battery 2's charge level exceeds a threshold (e.g., 80%). After time t2, when the catalyst temperature begins to decrease, the vehicle controller 7 gradually returns the central charge level to its original value.

[0048] At time t3, the catalyst temperature is lower than, for example, the second reference temperature (T c2 When the temperature reaches the upper limit temperature (T330°C, for example) and the central charge rate reaches the original reference charge amount, the vehicle controller 7 sets the central charge rate to the reference charge amount and stops the discharge request. By controlling in this way, the temperature of the catalyst is kept above the upper limit temperature (T330°C). max ) (for example, to prevent it from exceeding 700°C).

[0049] Furthermore, in catalyst degradation suppression control, it is also preferable to increase the discharge amount of the battery 2 without changing the output of the generator 4. In this case, the frequency in which the charge rate of the battery 2 exceeds a threshold (e.g., 80%) decreases, so the frequency in which the 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 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 charging request unit 701 is a component that performs pre-charging request control. Map information is input to the charging request unit 701. of This refers to the terrain (elevation and gradient of the road surface) and traffic conditions (presence or absence of highways, etc.) of the route to the destination, for example, from the vehicle's current location to a predetermined distance (e.g., 5 km or 10 km) ahead, and indicates the vehicle's future driving conditions.

[0052] The charging request unit 701 refers to map information and determines, for example, if the vehicle is currently traveling on flat ground but a predetermined uphill slope begins 2 kilometers ahead and continues for a predetermined distance or longer, it will perform high-load operation that consumes more power from the battery 2 than normal operation. Here, normal operation refers to, for example, a vehicle traveling on a flat, ordinary road at a normal speed (for example, 60 km / h). h This refers to the state in which the vehicle is running under load conditions. Furthermore, high-load operation refers to the state in which the power supply from the generator 4 to the drive motor 1 is kept approximately constant, while the power supply from the battery 2 to the drive motor 1 is significantly increased to drive the vehicle.

[0053] The charging request unit 701 calculates the amount of work required to climb the detected uphill slope, and based on that amount of work, calculates a first central charge rate (for example, the minimum charge rate that pre-charging request control is generally permissible) as the amount of charge of the battery 2 that can cover that amount of work, and outputs it to the request adjustment unit 703. As a result, it becomes unnecessary to increase the output of the generator 4 during high-load operation, thereby improving the noise and vibration performance of the vehicle.

[0054] Furthermore, if the charging request unit 701 determines, for example, that it is currently driving on an ordinary road but will enter a highway 2 kilometers ahead and perform high-speed driving (high-load driving), it calculates the amount of work required for high-speed driving and, based on that amount of work, calculates a first central charge rate as the amount of charge that the battery 2 can handle, and outputs this to the request adjustment unit 703.

[0055] Furthermore, the charging request unit 701 may receive input such as road gradient, altitude, and vehicle speed, and the first central charge rate may be corrected based on this information. The charging request unit 701 may also correct the first central charge rate so that it increases as the gradient becomes steeper, the vehicle speed increases, and the altitude increases.

[0056] The discharge request unit 702 is a component that performs catalyst degradation suppression control. When the catalyst temperature is input to the discharge request unit 702, it calculates the rate at which the catalyst temperature rises. Then, based on the map shown in Figure 3, it calculates the second central charge rate (for example, the maximum charge rate that catalyst degradation suppression control is generally permissible) and outputs it to the request adjustment unit 703.

[0057] Furthermore, the discharge request unit 702 can be configured to input the aforementioned map information, and if, for example, it is expected that the catalyst temperature will reach the first reference temperature at a distance of 2 kilometers from the vehicle, and that a downhill slope with a predetermined gradient will begin at that distance, and that this downhill slope will continue for a predetermined distance or longer, the second central charge rate can be set to an even lower value.

[0058] The request adjustment unit 703 calculates the final central charge rate by comparing the reference charge rate, the first central charge rate output from the charge request unit 701, and the second central charge rate output from the discharge request unit 702, as described below.

[0059] [Map of Request Adjustment Unit 703] Figure 6 shows a map of the request adjustment unit 703 that constitutes the vehicle controller 7, and based on the first central charge rate (Y) calculated by the charge request unit 701 and the second central charge rate (X) calculated by the discharge request unit 702, the vehicle controller 7 makes discharge requests and charging This is a map for calculating the central charge level (Z), which is used as the criterion for determining the requirements.

[0060] The vertical axis in Figure 6 represents the first central charge level (Y), which corresponds to the lower limit of the charge level of battery 2 requested by the charge request unit 701. The horizontal axis in Figure 7 represents the second central charge level (X), which corresponds to the upper limit of the charge level of battery 2 requested by the discharge request unit 702. The reference charge level is set, for example, to X=X1, Y=Y1 (X1=Y1=55[%]).

[0061] The request adjustment unit 703 sets the central charge rate (Z) to either the first central charge rate (Y) or the second central charge rate (X) if the first central charge rate (Y) and the second central charge rate (X) are the same (i.e., they overlap with the Y=X line shown in Figure 6).

[0062] More specifically, if the first central charge rate (Y) and the second central charge rate (X) are the same value and higher than the reference charge rate, the request adjustment unit 703 sets the central charge rate (Z) according to the request from the charge request unit 701, rather than following the request from the discharge request unit 702. Also, if the first central charge rate (Y) and the second central charge rate (X) are the same value and lower than the reference charge rate, the request adjustment unit 703 sets the central charge rate (Z) according to the request from the discharge request unit 702, rather than following the request from the charge request unit 701. Furthermore, if the first central charge rate (Y) and the second central charge rate (X) match the reference charge rate, the request adjustment unit 703 sets the central charge rate (Z) to the reference charge rate, rather than following the requests from the charge request unit 701 and the discharge request unit 702.

[0063] The request adjustment unit 703 sets the central charge rate (Z) to the reference charge rate, i.e., sets Z=X1=Y1, when the first central charge rate (Y) is lower than the second central charge rate (X), and the first central charge rate (Y) is lower than the reference charge rate and the second central charge rate (X) is higher than the reference charge rate (region A in Figure 6).

[0064] In this case, the reference charge rate is higher than the first central charge rate (Y) requested by the charge request unit 701, and lower than the second central charge rate (X) requested by the discharge request unit 702. Therefore, the reference charge rate satisfies the charge rates requested by both. Thus, the request adjustment unit 703 sets the central charge rate to the reference charge rate.

[0065] The request adjustment unit 703 sets the central charge rate (Z) to the first central charge rate (Y), i.e., sets Z=Y, when the first central charge rate (Y) is lower than the second central charge rate (X) and both the first central charge rate (Y) and the second central charge rate (X) are higher than the reference charge rate (region B in Figure 6). In this case, the catalyst degradation is substantially reduced. restraint Since no control is being performed, the request adjustment unit 703 sets the central charge level (Z) to the first central charge level (Y).

[0066] The request adjustment unit 703 sets the central charge rate (Z) to the second central charge rate (X), i.e., sets Z=X, when the first central charge rate (Y) is lower than the second central charge rate (X) and both the first central charge rate (Y) and the second central charge rate (X) are lower than the reference charge rate (region C in Figure 6). In this case, since no pre-charge request control is being performed in effect, the request adjustment unit 703 sets the central charge rate (Z) to the second central charge rate (X).

[0067] The request adjustment unit 703 adjusts the first central charge rate (Y) when it is higher than the second central charge rate (X) and the first central charge rate (Y) is higher than a predetermined lower limit (Y min For example, if it is lower than 46% (region D in Figure 6), the central charge level (Z) is set to the second central charge level (X), i.e., Z = X Set to this. If the first central charge rate (Y) requested by the charge request unit 701 is higher than the second central charge rate (X) requested by the discharge request unit 702, deciding which one to prioritize becomes somewhat complicated. However, the first central charging The rate (Y) is a predetermined lower limit (Y min If the value is lower than (X), it can be determined that pre-charging request control is not effectively being performed. In this case, the second central charge rate (X) is also lower than the predetermined charge rate (X). <X2=Y min ) However, catalyst degradation restraint The control is requesting a strong discharge. Therefore, the request adjustment unit 703, recognizing that there is a strong discharge request from the discharge request unit 702, adjusts the central charge level (Z) 2nd center charging rate (X) Set to this.

[0068] When the first center charging rate (Y) is higher than the second center charging rate (X) and the first center charging rate (Y) is higher than the lower limit value (Y min ) and higher than a predetermined upper limit value (Y max , for example, 69 [%]) (region E in FIG. 6), the center charging rate (Z) is set to the first center charging rate (Y), that is, Z = Y is set.

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

[0070] When the first center charging rate (Y) is higher than the second center charging rate (X) and the first center charging rate (Y) is between the lower limit value (Y min ) and the upper limit value (Y max ), and further when the second center charging rate (X) is lower than X2 = Y min (region F in FIG. 6), as the first center charging rate (Y) approaches the upper limit value (Y max ), the center charging rate (Z) is set to a value closer to the first center charging rate (Y), and as the first center charging rate (Y) approaches the lower limit value (Y min ), the center charging rate (Z) is set to a value closer to the second center charging rate (X). Here, X2 is the value of X obtained by substituting Y min into Y in the relational expression Y = X (FIG. 6) represented as a line on the coordinate space with the Y - coordinate of the first center charging rate (Y) and the X - coordinate of the second center charging rate (X), and is the same value as Y min .

[0071] In this case, the center charging rate (Z) can be expressed by the following formula (1) using the first center charging rate (Y), the second center charging rate (X), the lower limit value (Y min ), and the upper limit value (Y max ).

Equation

[0072] In the above case, the request adjustment unit 703 controls the pre-charge request and catalyst degradation. restraint Instead of prioritizing one control over the other, the system harmonizes the first central charge rate (Y) and the second central charge rate (X) to set a central charge rate (Z) that is not disadvantageous to either the pre-charge request control or the catalyst degradation control, thereby ensuring that both pre-charge request control and catalyst degradation control are prioritized. restraint We are striving to achieve a balance between control and functionality.

[0073] The request adjustment unit 703 adjusts the first central charge rate (Y) when it is higher than the second central charge rate (X) and the first central charge rate (Y) is lower than the lower limit (Y min ) and upper limit (Y max The value will be between ) and furthermore, the second central charge rate (X) will be X2 = Y min The above and X3 = Y max When it is lower than (region G in Figure 6), the central charge (Z) is set to the first central charge (Y), i.e., Z=Y. Here, X3 is the Y coordinate of the first central charge (Y) and the X coordinate is the second central charge (X), and in the relation Y=X (Figure 6), where X3 is the Y coordinate and Y is the X coordinate, Y max The value of X obtained by substituting Y max It has the same value as [the other value].

[0074] In this case, the request adjustment unit 703 determines that a strong charge request has been made as pre-charge request control and should be prioritized over catalyst degradation suppression control, and sets the central charge rate (Z) to the first central charge rate (Y).

[0075] [Control flow of vehicle controller 7] Figure 7 shows the vehicle controller 7 of This is a control flow diagram. In step S1, the vehicle controller 7 (discharge request unit 702) acquires information on the temperature of the catalyst (BED temperature). The vehicle controller 7 (charge request unit 701) also acquires map information related to the travel path immediately before the vehicle passes through, as part of the travel path information to the vehicle's destination.

[0076] In step S2, the vehicle controller 7 (discharge request unit 702) calculates the rate at which the catalyst temperature rises based on the previously acquired catalyst temperature and the currently acquired catalyst temperature, and calculates the second central charge rate based on the currently acquired temperature information, the calculated rate at which the catalyst temperature rises, 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 the first central charge rate based on the amount of work.

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

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

[0081] [Effects of this embodiment] In the hybrid vehicle control method of this embodiment, power is exchanged between the drive motor 1 and the battery 2, a generator 4 driven by a power-generating engine 3 charges the battery 2, and exhaust gas emitted from the engine 3 is treated by a catalyst (catalytic converter system 5). When the charge rate of the battery 2 exceeds a predetermined threshold (e.g., 80%) due to regenerative power received from the drive motor 1, the fuel supply to the engine 3 is stopped and the power generation of the generator 4 is stopped, and power is supplied from the battery 2 to the generator 4 to power the engine 3, thereby consuming the regenerative power. When the temperature of the catalyst (catalyst included in the catalytic converter system 5) is lower than the upper limit temperature (e.g., 700°C) that can suppress the deterioration of the catalyst, the discharge amount of the battery 2 is increased as the temperature of the catalyst (catalyst included in the catalytic converter system 5) approaches the upper limit temperature (e.g., 700°C), or as the rate of increase in the temperature of the catalyst (catalyst included in the catalytic converter system 5) increases.

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

[0083] In this embodiment, when controlling the charge rate according to a charge / discharge demand curve (Figure 2) that represents a trajectory in which the charge rate increases as the charge rate decreases below the central charge rate and the discharge rate increases as the charge rate increases above the central charge rate, the charge / discharge demand curve is shifted to the lower charge rate side by shifting the central charge rate to the lower charge rate side, as a discharge amount increase control (catalyst degradation suppression control) to increase the discharge amount of the battery 2.

[0084] The above method allows for a simple reduction in the central charge level before issuing a discharge request.

[0085] In this embodiment, when acquiring map information relating to the driving path immediately before the vehicle passes through the vehicle's destination, and when it is predicted that the vehicle will perform high-load operation that consumes more power from the battery 2 than normal operation by referring to the map information, pre-charge request control is performed to shift the central charge rate to the high charge rate side. If it is determined from the map information that the vehicle will climb an uphill slope of a predetermined distance or more, pre-charge request control is prioritized, and if it is determined from the map information that the vehicle will descend a downhill slope of a predetermined distance or more, discharge amount increase control (catalyst degradation suppression control) is prioritized.

[0086] Using the method described above, pre-charging request control and discharge rate increase control (catalyst degradation suppression control) can be selected and executed according to the road conditions being traveled on.

[0087] In this embodiment, when acquiring map information relating to the driving path immediately before the vehicle passes through the vehicle's destination, and when it is predicted that high-load operation consuming more power from battery 2 than normal vehicle operation will be performed by referring to the map information, pre-charge request control is performed to shift the central charge rate (Z) to the high charge rate side. Based on the map information, the amount of work for high-load operation is calculated, and the central charge rate requested by the pre-charge request control is calculated as the first central charge rate (Y) based on the amount of work, and the central charge rate requested by the discharge amount increase control (catalyst degradation suppression control) is calculated as the second central charge rate (X) based on the catalyst temperature or rise rate, and when the first central charge rate (Y) is higher than the second central charge rate (X), the first central charge rate (Y) is shifted to a predetermined lower limit (Y min If the central charge rate (Z) is lower than the lower limit (Y), the central charge rate (Z) is set to the second central charge rate (X), and if the first central charge rate (Y) is higher than the second central charge rate (X), the first central charge rate (Y) is set to the lower limit (Y min A predetermined upper limit (Y) that is higher than the value of ) max If the central charge rate (Z) is higher than the lower limit (Y), the central charge rate (Z) is set to the first central charge rate (Y), and if the first central charge rate (Y) is higher than the second central charge rate (X) and the first central charge rate (Y) is higher than the lower limit (Y) min ) and upper limit (Y max When the value falls between ) and the upper limit (Y)max The closer the central charge rate (Z) gets to the first central charge rate (Y), the closer the first central charge rate (Y) gets to the lower limit (Y min The closer the central charge level (Z) gets to the second central charge level (X), the closer it is set to the second central charge level (X).

[0088] As a result of the above method, in pre-charge request control, the priority increases as the first central charge rate (Y) increases, leading to catalyst degradation. restraint In the control system, the lower the second central charge rate (X), the higher the priority. Therefore, the system can determine the relative priority of pre-charge request control and catalyst degradation suppression control according to the road conditions, and execute both appropriately. Furthermore, when executing catalyst degradation suppression control, the charge rate of battery 2 is reduced in advance, which reduces the number of times the engine 3 motors when the catalyst temperature is below the upper limit temperature.

[0089] In this embodiment, when the first central charge rate (Y) and the second central charge rate (X) are the same, the central charge rate (Z) is set to the first central charge rate (Y) or the second central charge rate (X). When the first central charge rate (Y) is lower than the second central charge rate (X), and the first central charge rate (Y) is lower than the reference charge rate (Y1, for example 55%), and the second central charge rate (X) is higher than the reference charge rate (X1=Y1), the central charge rate (Z) is set to the reference charge rate. If the first central charge rate (Y) is lower than the second central charge rate (X) and both the first central charge rate (Y) and the second central charge rate (X) are higher than the reference charge rate, the central charge rate (Z) is set to the first central charge rate (Y). If the first central charge rate (Y) is lower than the second central charge rate (X) and both the first central charge rate (Y) and the second central charge rate (X) are lower than the reference charge rate, the central charge rate (Z) is set to the second central charge rate (X).

[0090] As a result of the above method, in pre-charge request control, the priority increases as the first central charge rate (Y) increases, leading to catalyst degradation. restraintIn the control system, the lower the second central charge rate (X), the higher the priority. Therefore, the system can determine the relative priority of pre-charge request control and catalyst degradation suppression control according to the road conditions, and execute both appropriately. Furthermore, when executing catalyst degradation suppression control, the charge rate of battery 2 is reduced in advance, which reduces the number of times the engine 3 motors when the catalyst temperature is below the upper limit temperature.

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

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

[0093] According to the control system of this hybrid vehicle, the system includes a drive motor 1, a battery 2 that exchanges power with the drive motor 1, a generator 4 that generates electricity and charges the battery 2 when driven by a power-generating engine 3, a catalyst (catalytic converter system 5) that processes exhaust gas emitted from the engine 3, and a control unit (vehicle controller 7, engine controller 8, motor controller 9) that controls the battery 2, engine 3, and generator 4. The control unit (vehicle controller 7, engine controller 8, motor controller 9) controls the system when the charge rate of the battery 2 exceeds a predetermined threshold (for example, 80%) due to regenerative power received from the drive motor 1. In a hybrid vehicle system that consumes regenerative power by stopping the fuel supply to the engine 3 and stopping 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 rate of the battery 2 as the temperature of the catalyst (catalyst included in catalyst system 5) approaches the upper limit temperature (e.g., 700°C) that can suppress the deterioration of the catalyst, or as the rate of increase in the temperature of the catalyst (catalyst included in catalyst system 5) increases, when the temperature of the catalyst (catalyst included in catalyst system 5) is lower than the upper limit temperature (e.g., 700°C) that can suppress the deterioration of the catalyst.

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

[0095] Although embodiments of the present invention have been described above, these embodiments represent only a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention 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 in which power is exchanged between a drive motor and a battery, a generator driven by an engine charges the battery, and exhaust gas emitted from the engine is treated by a catalyst, When the charge level of the battery exceeds a predetermined threshold due to the regenerative power received from the drive motor, the fuel supply to the engine is stopped, the generator stops generating power, and power is supplied from the battery to the generator to operate the engine, thereby consuming the regenerative power. A control method for a hybrid vehicle in which, when the temperature of the catalyst is lower than the upper limit temperature at which the deterioration of the catalyst can be suppressed, the amount of battery discharged increases as the rate of increase in the temperature of the catalyst increases.

2. In a coordinate space with the charge / discharge current and the charge level of the battery as axes, when the charge level is controlled according to a charge / discharge demand curve that includes a central charge level with a reference charge level at which the charge request and discharge request for the battery become zero as the initial value, and where the charge request increases as the charge level decreases below the central charge level, and the discharge request increases as the charge level increases above the central charge level, A control method for a hybrid vehicle according to claim 1, wherein, as a discharge amount increase control to increase the discharge amount of the battery, the charge / discharge request curve is shifted to the lower charge rate side by shifting the central charge rate to a lower charge rate side than the reference charge rate.

3. In the information of the vehicle's travel route to its destination, map information relating to the travel route immediately before the vehicle passes through is acquired, and when it is predicted that the vehicle will perform high-load operation that consumes more battery power than normal operation by referring to the map information, pre-charge request control is performed to shift the central charge rate to the high charge rate side, If the map information determines that the vehicle will climb an uphill slope of a predetermined distance or more, the pre-charge request control will be prioritized. The control method for a hybrid vehicle according to claim 2, wherein if it is determined from the map information that the vehicle is going down a slope of a predetermined distance or more, the discharge amount increase control is given priority.

4. In the information of the vehicle's travel route to its destination, map information relating to the travel route immediately before the vehicle passes through is acquired, and when it is predicted that the vehicle will perform high-load operation that consumes more battery power than normal operation by referring to the map information, pre-charge request control is performed to shift the central charge rate to the high charge rate side, Based on the map information, the amount of work performed during the high-load operation is calculated, and based on the amount of work, the central charge rate requested by the pre-charge request control is calculated as the first central charge rate. Based on the aforementioned rate of increase, the central charge rate required by the discharge amount increase control is calculated as the second central charge rate. If the first central charge rate is higher than the second central charge rate and the first central charge rate is lower than a predetermined lower limit, the central charge rate is set to the second central charge rate. If the first central charge rate is higher than the second central charge rate and the first central charge rate is higher than a predetermined upper limit that is higher than the lower limit, the central charge rate is set to the first central charge rate. A control method for a hybrid vehicle according to claim 2, in the case where the first central charge rate is higher than the second central charge rate and the first central charge rate is a value between the lower limit and the upper limit, the central charge rate is set to a value that approaches the first central charge rate as the first central charge rate approaches the upper limit, and the central charge rate is set to a value that approaches the second central charge rate as the first central charge rate approaches the lower limit.

5. When the first central charge rate and the second central charge rate coincide, the central charge rate is set to either the first central charge rate or the second central charge rate. If the first central charge rate is lower than the second central charge rate, and the first central charge rate is lower than the reference charge rate and the second central charge rate is higher than the reference charge rate, the central charge rate is set to the reference charge rate. If the first central charge rate is lower than the second central charge rate, and both the first and second central charge rates are higher than the reference charge rate, the central charge rate is set to the first central charge rate. A control method for a hybrid vehicle according to claim 4, wherein the first central charge rate is lower than the second central charge rate, and the first central charge rate and the second central charge rate are lower than the reference charge rate, the central charge rate is set to the second central charge rate.

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

7. The drive motor and A battery that exchanges power with the aforementioned drive motor, A generator that generates electricity and charges the battery by being driven by an engine for power generation, A catalyst for processing exhaust gas emitted from the aforementioned engine, The system includes a control unit that controls the battery, the engine, and the generator, In a hybrid vehicle control system in which the control unit stops supplying fuel to the engine and stopping the generator's power generation when the battery's charge level exceeds a predetermined threshold due to regenerative power received from the drive motor, and consumes the regenerative power by supplying power from the battery to the generator to power the engine, The control unit is a control system for a hybrid vehicle that increases the discharge rate of the battery as the rate of increase in the temperature of the catalyst increases, when the temperature of the catalyst is lower than the upper limit temperature at which the deterioration of the catalyst can be suppressed.

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