Hybrid vehicle control method and hybrid vehicle control device

Abstract

This hybrid vehicle control method includes: setting a water temperature increase request, a heating load assumption value, a travel load assumption value, and an SOC increase request as basic parameters; calculating, for each of a plurality of operating points of an internal combustion engine, a fuel consumption amount at a deadline time, which is a time after a warmup completion time at which warmup of the internal combustion engine is completed; selecting the operating point for which the fuel consumption amount is the lowest from among the plurality of operating points; and warming up the internal combustion engine in accordance with the selected operating point.

Description

Hybrid vehicle control method and hybrid vehicle control device

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

[0002] Patent Literature 1 discloses a control method for a hybrid vehicle that appropriately charges the battery and suppresses a decrease in engine coolant temperature. A controller performs motoring, driving the engine using a power-generating motor generator based on the battery's charging rate. The controller increases the motoring rotation speed in a driving section where the battery's charging rate is expected to increase, compared to a driving section where the battery's charging rate is not expected to increase.

[0003] JP 2017-214800 A

[0004] Motoring stops fuel injection into the internal combustion engine and runs the engine using electricity. Therefore, if motoring is performed while the engine is being warmed up, the temperature of the coolant that cools the internal combustion engine will drop. As a result, a lot of fuel will be consumed until the coolant temperature reaches the standard temperature, resulting in poor fuel economy.

[0005] An object of the present invention is to provide a control method and a control device for a hybrid vehicle that can warm up an internal combustion engine with the best fuel economy.

[0006] A control method for a hybrid vehicle according to one aspect of the present invention includes setting a water temperature increase request, an estimated heating load value, an estimated running load value, and an SOC increase request as basic parameters, calculating, for each of a plurality of operating points of the internal combustion engine, the fuel consumption at a cutoff time that is a time after the warm-up completion time at which warm-up of the internal combustion engine is completed, selecting an operating point from the plurality of operating points that results in the smallest fuel consumption, and warming up the internal combustion engine in accordance with the selected operating point.

[0007] According to one aspect of the present invention, it is possible to warm up an internal combustion engine with the best fuel economy.

[0008] FIG. 1 is a block diagram showing the configuration of a hybrid vehicle according to this embodiment. FIG. 2 is a flowchart showing warm-up control according to this embodiment. FIG. 3 is a flowchart showing the processing of a warm-up plan. FIG. 4 is a flowchart showing the processing of a warm-up plan. FIG. 5 is a graph showing heat demand and power demand. FIG. 6 is a graph showing the relationship between heat demand and power demand and heat generation output and power generation output. FIG. 7 is a diagram showing a state in which power generation output has reached the SOC upper limit. FIG. 8 is a graph showing the relationship between heat demand and power demand and heat generation output and power generation output when the second heater is used. FIG. 9 is a diagram explaining motoring time. FIG. 10 is a diagram showing the transition of fuel consumption. FIG. 11 is a diagram showing the transition of fuel consumption corresponding to three operating points. FIG. 12 is a diagram showing warm-up control by a controller.

[0009] A hybrid vehicle (hereinafter referred to as "vehicle") 1 according to this embodiment includes a drive motor 10, a battery 11, a power generation system 12, a heater 13, and a controller 20.

[0010] The drive motor 10 is connected to the wheels (drive wheels) via a differential mechanism. The drive motor 10 drives the drive wheels with electric power and also generates electric power regeneratively during deceleration. The battery 11 stores electric power. The battery 11 stores electric power generated by the power generation system 12 and electric power regenerated by the drive motor 10. The electric power of the battery 11 is supplied to the drive motor 10, a heater 13, etc.

[0011] The power generation system 12 generates electric power using fuel. The power generation system 12 includes an engine 16 and a generator 17. The engine 16 is an internal combustion engine such as a gasoline engine or a diesel engine, and is driven by fuel. The engine 16 is connected to the generator 17 via a reduction gear mechanism. The generator 17 is driven by the engine 16 to generate electric power. The electric power of the generator 17 is input to the battery 11. Note that the battery 11 may be discharged by driving the generator 17 with the electric power of the battery 11 to rotate the engine 16 (so-called motoring).

[0012] The heater 13 heats the interior of the vehicle 1. The heater 13 is part of a heating, ventilation, and air conditioning (HVAC) system (not shown) provided in the vehicle 1. The heater 13 includes a first heater 18 and a second heater 19.

[0013] The first heater 18 is a first heating device that heats the interior of the vehicle 1 using heat generated by the engine 16. The first heater 18 is provided in a circulation path for coolant or other refrigerant (hereinafter simply referred to as "coolant") that cools the engine 16. The first heater 18 supplies warm air into the interior of the vehicle 1 using the heat of the coolant heated by the engine 16. The temperature of the coolant (hereinafter referred to as "water temperature") is also a parameter that indicates the temperature of the engine 16.

[0014] The second heater 19 is a second heating device that heats the interior of the vehicle 1 using heat obtained from the power of the battery 11. The second heater 19 includes, for example, a PTC (Positive Temperature Coefficient) heater. The second heater 19 supplies warm air into the interior of the vehicle 1 using heat generated in the PTC heater.

[0015] The controller 20 is configured with a microcomputer equipped with a CPU, ROM, RAM, and an input / output interface. The controller 20 is a control device that controls the vehicle 1 by executing a program stored in the ROM or RAM by the CPU. The program for controlling the vehicle 1 may be provided in a form stored in a storage medium such as a CD-ROM, an SD card, or a hard disk. The program for controlling the vehicle 1 may also be provided by communication with a device or the like external to the vehicle 1 (such as a server or a cloud service).

[0016] In the vehicle 1 configured as described above, the power of the engine 16 is transmitted to the generator 17. The generator 17 generates electric power from the power transmitted from the engine 16. The electric power is stored in the battery 11. The battery 11 also stores electric power generated by the drive motor 10 when the vehicle decelerates. The drive motor 10 is supplied with electric power from the battery 11. The drive motor 10 receives electric power and generates power, which is transmitted to the drive wheels via a differential mechanism. The hybrid system applied to the vehicle 1 is a series hybrid system in which the engine 16 is used to drive the generator 17 and the drive wheels are driven by the drive motor 10.

[0017] Various sensors (not shown) are also mounted on the vehicle 1. The controller 20 can acquire information necessary for calculations, which will be described later, from these sensors.

[0018] A control method for the vehicle 1 according to this embodiment, specifically, warm-up control of the engine 16 when the vehicle is started, will be described with reference to Fig. 2. The flowchart shown in Fig. 2 is executed by the controller 20 when the start switch for starting the vehicle 1 is turned on as a trigger.

[0019] First, in step S1, the controller 20 sets various parameters, specifically, a water temperature increase request [°C], an estimated heating load [kW], an estimated running load [kW], an SOC upper limit [%], and an SOC increase request [%]. Note that SOC refers to the state of charge of the battery 11.

[0020] The water temperature increase request is a requested value indicating how much the engine 16 coolant temperature should be increased. The controller 20 sets the water temperature increase request based on the difference between the current water temperature and a reference water temperature, which is a reference value for the coolant temperature at which warm-up is completed (hereinafter referred to as "water temperature"). In other words, the water temperature increase request corresponds to the temperature increase amount required to increase the water temperature from the current temperature to the reference water temperature. The estimated heating load value is the load expected on the heater 13, i.e., the estimated output value of the heater 13. The controller 20 sets the estimated heating load value based on the set temperature of the heater 13, the outside air temperature, and other factors. The estimated driving load value is the load expected on the drive motor 10 due to the driving of the vehicle 1, i.e., the estimated output value of the drive motor 10. The controller 20 sets the estimated driving load value based on the vehicle model and the current driving conditions, such as urban driving or highway driving. The controller 20 sets the estimated driving load value based on a pre-prepared design value. The SOC upper limit is an SOC that ensures a certain amount of free capacity in the battery 11 for storing regenerative power. The SOC increase request is a requested value indicating by what percentage the SOC of the battery 11 should be increased. The controller 20 sets the SOC increase request based on the difference between the reference SOC, which is a reference value of the SOC at which warm-up is completed, and the current SOC. In other words, the SOC increase request corresponds to the SOC increase amount required to increase the SOC from the current SOC to the reference SOC. The reference SOC is set in advance as an SOC lower than the SOC upper limit.

[0021] The controller 20 may store data on the heating load and the running load in a storage device each time the user uses the vehicle 1. In this case, the controller 20 may use this data to set the estimated heating load value and the estimated running load value. The storage device may be installed in the vehicle 1 or may be an external device such as a cloud.

[0022] In step S2, the controller 20 formulates an optimal warm-up plan (optimal warm-up plan) based on the water temperature increase request, the estimated heating load, the estimated running load, and the SOC increase request. The optimal warm-up plan determines the operating point (combination of engine speed and torque) and second heater output of the engine 16 that minimizes fuel consumption. The optimal warm-up plan will be described with reference to FIG. 3 .

[0023] First, in step S10, the controller 20 selects an operating point to be processed from a plurality of pre-prepared operating points of the engine 16. Here, the operating point of the engine 16 is defined by a combination of the rotation speed and the torque.

[0024] In step S11, the controller 20 sets a cut-off time. As will be described later, the time it takes for the warm-up to be completed (warm-up completion time) differs for each operating point of the engine 16, so a cut-off time is necessary for evaluating each operating point. The cut-off time is set to a value through experiments and simulations so that it is longer than each warm-up completion time.

[0025] In step S12, the controller 20 calculates the warm-up completion time, the second heater output, and the fuel consumption amount. The process of step S12 will be described below with reference to FIG.

[0026] In step S20, the controller 20 calculates the slope and intercept of the heat demand using the following formulas: Slope of heat demand = Estimated heating load value [kW] / 3600 (Formula 1) Intercept of heat demand = Water temperature increase demand × Specific heat capacity (Formula 2)

[0027] The controller 20 calculates the transition (integrated value) of the heat demand required for warm-up from the slope and intercept of the heat demand. The transition of the heat demand is represented by the line segment Hr in a graph, as shown in Figure 5, with the horizontal axis representing time (seconds) and the vertical axis representing the integrated value (kWh). In Figure 5, Th is the intercept of the heat demand. In other words, this heat demand line segment Hr indicates the amount of heat required until the water temperature reaches the reference water temperature (water temperature heat demand).

[0028] In step S21, the controller 20 calculates the slope and intercept of the power request using the following formulas: Slope of power request = Estimated running load value [kW] / 3600 (Formula 3) Intercept of power request = SOC increase request × Battery capacity (Formula 4)

[0029] The controller 20 calculates the transition (integrated value) of the power requirement required for the vehicle 1 from the slope and intercept of the power requirement. The transition of the power requirement is represented by a line segment Pr in a graph, as shown in Fig. 5, with the horizontal axis representing time [seconds] and the vertical axis representing the integrated value [kWh]. In Fig. 5, Tg corresponds to the intercept of the power requirement. That is, the power requirement line segment Pr indicates the amount of power required until the SOC reaches the reference SOC (SOC required power amount).

[0030] In step S22, the controller 20 calculates the gradient of the power generation output and the gradient of the heat generation output using the following formulas: Gradient of power generation output = Power generation output [kW] / 3600 (Formula 5) Gradient of heat generation output = Heat generation output [kW] / 3600 (Formula 6)

[0031] Here, the power generation output is the output of the generator 17 when the engine 16 is operated at the operating point selected in step S10, and is calculated from the engine speed and torque corresponding to the operating point. The heat generation output is the heat generation output of the engine 16 when the engine 16 is operated at the selected operating point, and is calculated from the engine speed and torque.

[0032] The controller 20 obtains the graph shown in FIG. 6 by plotting the slopes of the power generation output and the heat generation output on the graph shown in FIG. 5 . In FIG. 6 , line segments Pe and He represent the power generation output and the heat generation output, respectively, and are straight lines with zero intercepts. The line segment Pe for the power generation output represents the change (integrated value) in the amount of electric power output from the generator 17 when the engine 16 is operated at the selected operating point. The line segment He for the heat generation output represents the change (integrated value) in the amount of heat output from the engine 16 when the engine 16 is operated at the selected operating point. The controller 20 determines the time at which the line segment He for the heat generation output intersects with the line segment Hr for the heat request as the required water temperature arrival time sh [s] at which the water temperature reaches the reference water temperature. In other words, the required water temperature arrival time sh is the time at which the amount of heat output from the engine 16 reaches the required water temperature heat amount when the engine 16 is operated at the selected operating point. Similarly, the controller 20 determines the time at which the power generation output line Pe and the power request line Pr intersect as the SOC request arrival time sg [s] at which the SOC reaches the reference SOC. That is, the SOC request arrival time sg is the time at which the amount of power output from the generator 17 reaches the SOC request amount when the engine 16 is operated at the selected operating point.

[0033] The controller 20 compares the required water temperature arrival time sh with the required SOC arrival time sg and determines the longer time as the warm-up completion time [s]. In the example shown in Fig. 6, the required water temperature arrival time sh is the warm-up completion time. Note that the power generated between the required SOC arrival time sg and the required water temperature arrival time sh is the surplus power ΔP.

[0034] In step S23, the controller 20 determines the second heater output. As shown in FIG. 7 , if the required water temperature arrival time sh is longer than the required SOC arrival time sg, i.e., if the gradient of the heat request (line segment Hr) is steep, the SOC may reach the SOC upper limit (the line indicated by "Su" in FIG. 7 ) before the water temperature reaches the reference water temperature. In this case, the power generated until the water temperature reaches the reference water temperature becomes surplus power ΔP. Therefore, by operating the second heater 19 and having the second heater 19 cover part of the heat request, the rate at which the SOC increases can be suppressed and fuel consumption can be reduced.

[0035] The slope of the heat requirement (line segment Hr) and the slope of the power requirement (line segment Pr) when the second heater is used can be calculated using the following formulas: Slope of heat requirement when the second heater is used = (estimated heating load value [kW] - second heater output [kW]) / 3600 (Formula 7) Slope of power requirement when the second heater is used = (estimated driving load value [kW] + second heater output [kW]) / 3600 (Formula 8)

[0036] The ideal second heater output is the output when the required water temperature arrival time sh and the required SOC arrival time sg are the same. The required water temperature arrival time sh and the required SOC arrival time sg are expressed by the following equations: sh=b0_V / (bH-bV+PTC) (Equation 9) sg=b0_E / (bG-bE-PTC) (Equation 10)

[0037] Here, b0_V is the intercept of the heat demand [kWh], bV is the estimated heating load value [kW], bH is the heat generation output of the engine 16 [kW], b0_E is the intercept of the power demand [kWh], bE is the estimated running load value [kW], bG is the power generation output [kW], and PCT is the second heater output [kW].

[0038] When sh=sg and solving for PTC, the ideal value of the second heater output is expressed by the following equation: PTC (ideal value)={b0_V*(bG-bE)-b0_E*(bH-bV)} / (b0_E+b0_V) (Equation 11)

[0039] Since it is necessary to take into consideration the maximum output of the second heater 19, the controller 20 determines the second heater output using the following formula. That is, the controller 20 determines the larger value of the ideal value of the second heater output and the maximum output of the second heater 19 as the second heater output: PTC=max(PTC(ideal value), PTC(maximum output)) (Formula 12)

[0040] On the other hand, when the required water temperature arrival time sh is equal to or shorter than the required SOC arrival time sg, the required water temperature arrival time sh is reached before the required SOC arrival time sg is reached, so that the second heater 19 does not need to be used.

[0041] In step S24, the controller 20 changes the slope of the heat request (line segment Hr) and the slope of the power request (line segment Pr) based on the second heater output. As shown in Fig. 8, when the required water temperature arrival time sh and the required SOC arrival time sg are the same, the slope of the heat request (line segment Hr) decreases and the slope of the power request (line segment Pr) increases compared to when the second heater 19 is not used (see Fig. 7).

[0042] In step S25, the controller 20 calculates the time for motoring (motoring time). If the SOC reaches the SOC upper limit while the engine 16 is being operated using the selected operating point, it is necessary to perform the minimum amount of motoring necessary to achieve warm-up. In calculating the motoring time, the motoring output is determined in advance. Then, by calculating the motoring time and the warm-up time including the motoring time, it is possible to calculate an optimal solution even when there are constraints on the SOC.

[0043] First, when the SOC reaches the SOC upper limit, Equation 13 holds for heat, and Equation 14 holds for power. H1 + (Sm + S2) × bV = S2 × bH (Equation 13) bE × (Sm + S2) = bG × S2 - bm × Sm (Equation 14)

[0044] Here, as shown in FIG. 9, H1 refers to the shortfall in heat generation amount relative to the heat demand when the SOC reaches the SOC upper limit. bV is the slope of the heat demand. bE is the slope of the power demand. bH is the slope of the heat generation output. bG is the slope of the power generation output. bm is the slope of the motoring output. S1 is the time it takes for the SOC to reach the SOC upper limit. S2 is the time from the end of motoring until warm-up is complete. Sm is the motoring time.

[0045] Solving equations 13 and 14 for S2 gives the following equations 15 and 16: S2=(H1+Sm×bV) / (bH−bV) (equation 15) S2=Sm×(bE+bm) / (bG−bE) (equation 16)

[0046] From these equations 15 and 16, the motoring time (Sm) can be calculated (equation 17). The controller 20 calculates the motoring time using equation 17. Sm = H1 × (bG - bE) / {(bE + bm) × (bH - bV) - bV × (bG - bE)} (equation 17)

[0047] In step S23, the controller 20 determines whether the selected operating point satisfies the required values. The selected operating point satisfies the required values ​​when, as shown in the following equations, the heat output of the engine 16 and the power output of the generator 17 exceed the estimated heating load and estimated running load, respectively, when the engine 16 is operated at the selected operating point. bG - bE > 0 (Equation 18) bH - bV > 0 (Equation 19)

[0048] When Equation 18 is true, the numerator of Equation 17 above is a positive value. In order for the motoring time Sm to be true, the denominator of Equation 17 must also be a positive value. (bE + bm) × (bH - bV) - bV × (bG - bE) > 0 (Equation 20)

[0049] The equation obtained by solving equation 20 for the motoring output bm is shown below: bm>bV×(bG−bE) / (bH−bV)−bE (Equation 21)

[0050] If equation 21 is satisfied, the controller 20 determines that the selected operating point satisfies the required value (S26: YES), and if equation 21 is not satisfied, the controller 20 determines that the selected operating point does not satisfy the required value (S26: NO).

[0051] If the selected operating point satisfies the required value, the controller 20 calculates the time at which the heat output line segment He and the heat request line segment Hr (if the slope has been changed in step S24, the changed heat request line segment Hr) intersect as the required water temperature arrival time sh [s] for the water temperature to reach the reference water temperature (S27). As described above, if the motoring time is calculated, the motoring time is also added to this required water temperature arrival time.

[0052] In step S28, the controller 20 determines whether the required water temperature arrival time is shorter than the cutoff time. If the required water temperature arrival time is shorter than the cutoff time (S28: YES), the controller 20 determines that warm-up is successful for the selected operating point (S29). On the other hand, if the required water temperature arrival time is longer than the cutoff time (S28: NO), or if the selected operating point does not satisfy the required value (S26: NO), the controller 20 determines that warm-up is not successful for the selected operating point (S29).

[0053] In step S31, the controller 20 calculates the amount of fuel consumed per unit time when the engine 16 is operated at the selected operating point until the warm-up completion time.

[0054] 3, the controller 20 calculates the fuel consumption per unit time after the warm-up is completed, i.e., the fuel consumption per unit time in a steady state. The fuel consumption per unit time in the steady state can be a value previously set through experiments or simulations.

[0055] In step S14, the controller 20 calculates the fuel consumption amount at the deadline. Specifically, the controller 20 calculates the fuel consumption amount up to the warm-up completion time based on the fuel consumption amount calculated in step S31 of FIG. 4 and the required water temperature arrival time. Similarly, the controller 20 calculates the fuel consumption amount from the warm-up completion to the deadline based on the fuel consumption amount calculated in step S13, the required water temperature arrival time, and the deadline. The controller 20 then calculates the fuel consumption amount at the deadline by adding the fuel consumption amount up to the warm-up completion to the fuel consumption amount from the warm-up completion to the deadline. Line P1 in FIG. 10 shows the change in fuel consumption when motoring is performed during the warm-up period, and time Tf1 indicates the warm-up completion time. Line P2 in FIG. 10 shows the change in fuel consumption when motoring is not performed during the warm-up period, and time Tf2 indicates the warm-up completion time. In FIG. 10, time Tc indicates the deadline.

[0056] In step S15, the controller 20 determines whether or not calculations have been completed for all operating points. If calculations have not been completed for all operating points (S15: NO), the controller 20 selects a new operating point and performs the above-described processing (steps S10 to S14).

[0057] When calculations for all operating points are completed (S15: NO), the controller 20 selects the operating point that minimizes fuel consumption (step S16). Fig. 12 is a diagram showing fuel consumption corresponding to three operating points Pa, Pb, and Pc. In Fig. 12, Tfa, Tfb, and Tfc are the warm-up completion times for the three operating points Pa, Pb, and Pc, respectively, and Tc is the deadline. Operating point Pa completes warm-up the fastest, but does not have the smallest fuel consumption at the deadline. In this case, operating point Pb minimizes fuel consumption at the warm-up deadline, and this operating point Pb is the optimal solution.

[0058] Through this series of processes, the controller 20 can formulate an optimal warm-up plan (S2). That is, the controller 20 can formulate a water temperature increase plan (relationship between time and water temperature increase) and an SOC increase plan (relationship between time and SOC increase) from the estimated heating load value described above and the planned values ​​of heat generation output and power generation output at the operating point where fuel consumption is minimized. The warm-up plan also includes the planned values ​​of the operating point (rotation speed and torque) of the engine 16, the second heater output, the motoring time, and the output, which are calculated in the above-mentioned processes.

[0059] In step S3 shown in FIG. 2 , the controller 20 starts warming up. In step S4, the controller 20 performs control in accordance with the warm-up plan set in step S2. That is, the controller 20 controls the operating point of the engine 16 so as to conform to the water temperature increase plan and the SOC increase plan. When warm-up is controlled according to the optimal plan, the estimated heating load and the estimated road load do not always match the actual values. In this case, the difference between the estimated values ​​and the actual values ​​may delay the increase in the water temperature and the SOC. Therefore, the controller 20 must control the engine 16 rotation speed and torque and the second heater 19 to change the water temperature and the SOC as planned. As shown in FIG. 12 , the controller 20 monitors the difference between the planned values ​​of the water temperature and the SOC and their actual values. The controller 20 uses PID control to correct the operating point of the engine 16 and the second heater output from the planned values ​​in accordance with the difference between the planned values ​​and the actual values.

[0060] In step S5, the controller 20 determines whether there has been a change in the heating load or the road load. If there has been a change in the heating load or the road load (S5: YES), the controller 20 re-executes the optimal warm-up plan of step S2 in accordance with the changed load. If there has been no change in the heating load or the road load (S5: NO), the controller 20 determines whether the water temperature has reached the reference water temperature and the SOC has reached the reference SOC (S6).

[0061] If the water temperature and SOC have not reached their respective reference values ​​(S6: NO), the controller 20 performs control in accordance with the warm-up schedule. On the other hand, if the water temperature and SOC have reached their respective reference values ​​(S6: YES), the controller 20 ends the warm-up.

[0062] As described above, the control method for vehicle 1 according to this embodiment includes setting the water temperature increase request, the estimated heating load value, the estimated running load value, and the SOC increase request as basic parameters, calculating the fuel consumption at a deadline that is later than the predetermined time based on the basic parameters for each of a plurality of operating points of the internal combustion engine, selecting the operating point from the plurality of operating points that results in the smallest fuel consumption, and warming up the internal combustion engine according to the selected operating point.

[0063] According to this method, the fuel consumption at the cutoff time, which is a time after the warm-up completion time, is calculated instead of the fuel consumption at the warm-up completion time when the warm-up of the engine 16 is completed. This makes it possible to evaluate the fuel consumption until a steady state is reached after the warm-up completion for each operating point during warm-up. As a result, it is possible to select the operating point with the smallest overall fuel consumption, rather than the fuel consumption until the warm-up completion, and therefore it is possible to warm up the engine 16 with the best fuel economy.

[0064] The control method for vehicle 1 according to this embodiment includes calculating a water temperature required heat quantity required for the water temperature to reach a reference water temperature based on a water temperature increase request and an estimated heating load value, and calculating an SOC required power quantity required for the SOC to reach a reference SOC based on an SOC increase request and an estimated running load value. The control method also includes calculating a water temperature required arrival time required for the amount of heat output from engine 16 to reach the water temperature required heat quantity when engine 16 is operated at an operating point, and calculating an SOC required arrival time required for the amount of power output from generator 17 to reach the SOC required power quantity when engine 16 is operated at the operating point. The control method also includes comparing the water temperature required arrival time and the SOC required arrival time and determining the longer of these as the warm-up completion time.

[0065] According to this method, the warm-up completion time for each operating point can be calculated with high accuracy.

[0066] The control method for vehicle 1 according to this embodiment includes calculating the fuel consumption at the deadline by adding the fuel consumption of engine 16 up to the warm-up completion time and the fuel consumption of engine 16 from the warm-up completion time to the deadline time.

[0067] This method allows the fuel consumption to be calculated with high accuracy.

[0068] The control method for the vehicle 1 according to this embodiment includes calculating a motoring time for performing motoring to drive the engine 16 by the traction motor 10 when the SOC is expected to reach the SOC upper limit before the required water temperature arrival time is reached. In this case, the required water temperature arrival time is calculated taking the motoring time into consideration.

[0069] According to this method, even in a situation where the SOC is limited by the SOC upper limit, it is possible to calculate the optimal operating point, thereby enabling the control method according to this embodiment to be implemented without failure.

[0070] In this embodiment, the heater 13 includes a first heater 18 that heats the interior of the vehicle using heat from the coolant heated by the engine 16, and a second heater 19 that heats the interior of the vehicle using heat generated from the power of the battery 11. In this case, the control method for the vehicle 1 determines the output of the second heater 19 when the required water temperature arrival time is longer than the required SOC arrival time so that the required water temperature arrival time is the same as the required SOC arrival time.

[0071] According to this method, it is possible to calculate the warm-up time and fuel consumption amount taking into account the use of the second heater 19. This makes it possible to further reduce fuel consumption amount.

[0072] The control method for the vehicle 1 according to this embodiment includes correcting the operating point of the engine 16 and the output of the second heater 19 from the planned values ​​in accordance with the difference between the planned values ​​of the water temperature and SOC and the actual values ​​of the water temperature and SOC.

[0073] According to this method, when a difference occurs between the planned values ​​of the water temperature and the SOC and the actual values ​​thereof, the operating point of the engine 16 and the second heater output can be corrected from the planned values, thereby allowing the water temperature and the SOC to be increased appropriately according to the plan.

[0074] In addition, the control method for vehicle 1 according to this embodiment may set the estimated heating load value and the estimated running load value based on heating load and running load data stored in a storage device. This method allows the characteristics of the user to be taken into consideration, and therefore the estimated heating load value and the estimated running load value can be calculated with high accuracy.

[0075] The above-described embodiment describes the warm-up at the start of the vehicle 1. However, the control method according to the present embodiment may also be performed when resuming normal driving after the water temperature has dropped due to a long period of traffic congestion, etc.

[0076] The present embodiment also includes a control device for the vehicle 1. The control device for the vehicle 1 includes the above-described controller 20. The control device for the hybrid vehicle 1 can warm up the engine 16 with the best fuel economy.

[0077] Although the embodiments of the present invention have been described above, the descriptions and drawings that form part of this disclosure should not be understood to limit the present invention. Various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art from this disclosure.

[0078] REFERENCE SIGNS LIST 1 Hybrid vehicle 10 Drive motor 11 Battery 12 Power generation system 13 Heater 16 Engine 17 Generator 18 First heater 19 Second heater

Claims

1. A control method for a hybrid vehicle equipped with an internal combustion engine and a power generation system including a generator driven by the internal combustion engine to generate electricity, a battery that stores electricity, and a drive motor that generates driving force for wheels using the electricity stored in the battery, the control method comprising: setting, as basic parameters, a water temperature increase request indicating the temperature increase amount for raising the water temperature of the cooling water that cools the internal combustion engine to a reference water temperature, an estimated heating load value which is the load expected on a heater, an estimated running load value which is the load expected on the drive motor due to the running of the hybrid vehicle, and an SOC increase request indicating the SOC increase amount for raising the SOC of the battery to a reference SOC; calculating, for each of a plurality of operating points of the internal combustion engine, the fuel consumption at a cutoff time which is a time after the warm-up completion time when warm-up of the internal combustion engine is completed, based on the basic parameters; selecting, from the plurality of operating points, the operating point which produces the smallest fuel consumption; and warming up the internal combustion engine according to the selected operating point.

2. A control method for a hybrid vehicle as described in claim 1, comprising: calculating a water temperature required heat quantity required for the water temperature to reach the reference water temperature based on the water temperature increase request and the heating load estimated value; calculating an SOC required power quantity required for the SOC to reach the reference SOC based on the SOC increase request and the running load estimated value; calculating a water temperature required arrival time at which the heat quantity output from the internal combustion engine when operated at the operating point will reach the water temperature required heat quantity; calculating an SOC required arrival time at which the power quantity output from the generator when operated at the operating point will reach the SOC required power quantity; comparing the water temperature required arrival time with the SOC required arrival time, and determining the longer time as the warm-up completion time.

3. A control method for a hybrid vehicle according to claim 1 or 2, wherein the fuel consumption amount at the cut-off time is calculated by adding the fuel consumption amount of the internal combustion engine up to the warm-up completion time and the fuel consumption amount of the internal combustion engine from the warm-up completion time to the cut-off time.

4. A control method for a hybrid vehicle as described in claim 2, wherein, if the SOC is expected to reach an SOC upper limit before the required water temperature arrival time is reached, a motoring time for performing motoring to drive the internal combustion engine using the drive motor is calculated, and the required water temperature arrival time is calculated taking into account the motoring time.

5. A control method for a hybrid vehicle as described in claim 2, wherein the heater includes a first heating device that heats the interior of the vehicle using heat from the coolant heated by the internal combustion engine, and a second heating device that heats the interior of the vehicle using heat generated from the power of the battery, and when the required water temperature arrival time is longer than the required SOC arrival time, the output of the second heating device is determined so that the required water temperature arrival time becomes the same as the required SOC arrival time.

6. A control method for a hybrid vehicle according to claim 5, wherein the operating point of the internal combustion engine and the output of the second heating device are corrected from their planned values ​​in accordance with the difference between the planned values ​​of the water temperature and the SOC and the actual values ​​of the water temperature and the SOC.

7. A control method for a hybrid vehicle as claimed in any one of claims 1 to 6, comprising storing data on heating load and running load when a user uses the hybrid vehicle in a storage device, and setting the estimated heating load value and the estimated running load value based on the data on heating load and running load.

8. A control device for a hybrid vehicle comprising: a power generation system including an internal combustion engine and a generator driven by the internal combustion engine to generate electricity; a battery that stores electricity; a drive motor that generates driving force for wheels using the electricity stored in the battery; and a controller, wherein the controller sets as basic parameters a water temperature increase request indicating the amount of temperature increase required to raise the temperature of the cooling water that cools the internal combustion engine to a reference water temperature, an estimated heating load value which is the load expected on a heater, an estimated running load value which is the load expected on the drive motor due to the running of the hybrid vehicle, and an SOC increase request indicating the amount of SOC increase required to raise the SOC of the battery to a reference SOC; for each of a plurality of operating points of the internal combustion engine, based on the basic parameters, calculates the fuel consumption at a cutoff time which is a time after the warm-up completion time when warm-up of the internal combustion engine is completed; selects an operating point from the plurality of operating points which results in the smallest fuel consumption; and warms up the internal combustion engine in accordance with the selected operating point.

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