Vehicle control system

Abstract

To provide a vehicle control device capable of achieving the improvement of a fuel consumption rate by reducing the operation frequency of an engine.SOLUTION: A vehicle control device includes executing processing of setting an internal combustion engine actuation request SOC to be low, and processing of actuating a water heating heater (step ST5), upon the establishment of the respective conditions: a travel mode is an HEV mode (YES determination in step ST1); an outside air temperature is equal to or less than a prescribed value (YES determination in step ST2); a distance to a destination of a vehicle is equal to or less than a prescribed distance (YES determination in step ST3); and a prediction time until next startup after vehicle stop is equal to or more than a prescribed time (YES determination in step ST4). With this, it is possible to reduce the operation frequency of an engine, and improve a fuel consumption rate.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a vehicle control device. In particular, the present invention relates to measures for reducing the operating frequency of an internal combustion engine in a vehicle equipped with an internal combustion engine and an electric motor as driving power sources for traveling.

Background Art

[0002] Conventionally, vehicles equipped with an internal combustion engine (hereinafter sometimes referred to as an engine) and an electric motor (hereinafter sometimes referred to as a traveling motor) as driving power sources for traveling, such as hybrid vehicles and plug-in hybrid vehicles, are known. In this type of vehicle, when the SOC (State Of Charge) of a drive battery (hereinafter sometimes referred to as a battery) that supplies power to the traveling motor decreases to a predetermined value during traveling in a so-called hybrid mode (HEV mode), the engine is operated to charge the battery. Further, when there is a heating requirement in the vehicle interior, ON / OFF control of the engine is performed according to the engine coolant temperature. That is, when the engine coolant temperature decreases to a predetermined value, the engine is operated to increase the engine coolant temperature.

[0003] Patent Document 1 proposes an example of ON / OFF control of an engine according to the engine coolant temperature. In this Patent Document 1, in a vehicle equipped with an engine and an auxiliary heater as a heat source for heating, when the auxiliary heater is not used, when the engine coolant temperature becomes lower than a threshold value predetermined according to the target blowing temperature, normal engine start request control is performed to prevent the temperature of the engine coolant from decreasing. On the other hand, when the auxiliary heater is used, power-saving engine ON request control is performed with a water temperature threshold lower than the water temperature threshold in the normal engine start request control to lengthen the engine stop time.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] As mentioned above, the inventors of this invention considered measures to further improve fuel consumption, given that simply controlling the engine ON / OFF according to the battery's SOC or engine coolant temperature has limitations in improving fuel consumption. For example, they noted that when starting in cold temperatures, the engine operates in response to the warm-up requirement, and if the engine is also operating just before arriving at the destination on the previous trip, this doubles the engine's operating frequency, worsening the overall fuel consumption. In other words, the inventors of this invention focused on the fact that the engine is controlled simply according to the battery's SOC or engine coolant temperature, regardless of the vehicle's driving conditions (distance to the destination, etc.), and gained new insight that there is room to improve fuel consumption in such a situation, leading to the present invention.

[0006] The present invention has been made in view of the above, and its objective is to provide a vehicle control device that can reduce the frequency of engine operation and improve fuel consumption. [Means for solving the problem]

[0007] The present invention provides a solution for achieving the above objective, which is based on a vehicle control device mounted on a vehicle that is equipped with an internal combustion engine and an electric motor as driving force sources for driving, and a water heater as a heat source for heating the vehicle interior, and which operates the internal combustion engine on the condition that the State of Charge (SOC) of the battery supplying power to the electric motor drops to the internal combustion engine operation request SOC. The vehicle control device then performs a process to set the internal combustion engine operation request SOC low and the process to operate the water heater when both of the following conditions (1) and (2) are met while driving in HEV mode using at least the internal combustion engine as the driving force source. togetherIt is characterized by execution. Condition (1) The outside air temperature is below a specified value. That is thing, Condition (2) The distance to the vehicle's destination is less than or equal to a specified distance. and The estimated time until the next start after the vehicle has stopped is longer than the specified time. That is thing.

[0008] This specific condition makes it highly likely that a heating request will arise inside the vehicle, and the distance to the vehicle's destination is less than a specified distance. and The estimated time until the next start after the vehicle has stopped is longer than the specified time. That is Therefore, in situations where it is not necessary to keep the battery's SOC high, the frequency of operation of the internal combustion engine can be reduced by setting the internal combustion engine operation request SOC low or by activating the water heater, thereby improving fuel consumption efficiency. [Effects of the Invention]

[0009] In this invention, during driving in HEV mode, condition (1) the outside air temperature is below a predetermined value. That is Condition (2) The distance to the vehicle's destination is less than or equal to a specified distance. and The estimated time until the next start after the vehicle has stopped is longer than the specified time. That is If both of the above conditions are met, the process of setting the internal combustion engine operating requirement SOC to a lower value and the process of activating the water heater are performed. together We are implementing this. This will reduce the frequency of operation of the internal combustion engine and improve fuel consumption. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of the vehicle control system according to the embodiment. [Figure 2] This figure shows a schematic of the cooling water circuit installed in a vehicle according to this embodiment. [Figure 3] This is a flowchart illustrating the procedure for controlling the reduction in engine operating frequency. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described based on the drawings. This embodiment describes the case in which the present invention is applied to a plug-in hybrid vehicle (PHEV).

[0012] Figure 1 is a schematic diagram of the vehicle control system according to this embodiment. As shown in Figure 1, the vehicle control system according to this embodiment includes an engine ECU 1, a motor ECU 2, a battery ECU 3, and an HEV_ECU (vehicle control device) 4. These ECUs 1 to 4 are configured as microprocessors centered on a CPU, and in addition to the CPU, they include a ROM for storing processing programs, a RAM for temporarily storing data, input / output ports, communication ports, etc. The vehicle according to this embodiment also includes a navigation system 5.

[0013] The engine ECU 1 controls the engine (internal combustion engine) 11 as the driving force source for the vehicle. Specifically, the engine ECU 1 receives signals from various sensors that detect the operating state of the engine 11 (for example, a crank position signal from the crank position sensor 12, an engine coolant temperature (internal combustion engine coolant temperature) signal from the water temperature sensor 13, and an outside air temperature signal from the outside air temperature sensor 14) via input ports, and outputs various control signals for driving the engine 11 via output ports. The engine ECU 1 also communicates with the HEV_ECU 4, and controls the operation of the engine 11 based on control signals from the HEV_ECU 4, and outputs data regarding the operating state of the engine 11 to the HEV_ECU 4 as needed.

[0014] The motor ECU2 controls two motor generators (electric motors) MG1 and MG2 (the first motor generator MG1, which mainly functions as a generator, and the second motor generator MG2, which mainly functions as an electric motor) through switching control of an inverter (not shown). Specifically, the motor ECU2 receives signals necessary to control motor generators MG1 and MG2 via its input ports, and outputs switching control signals to the switching elements of the inverter (not shown) via its output ports. The motor ECU2 also communicates with HEV_ECU4, controlling motor generators MG1 and MG2 based on control signals from HEV_ECU4, and outputting data regarding the operating status of motor generators MG1 and MG2 to HEV_ECU4 as needed.

[0015] The battery ECU3 manages a battery 31, which is configured as, for example, a lithium-ion secondary battery. The battery 31 exchanges power with motor generators MG1 and MG2 via an inverter. Specifically, the battery ECU3 receives signals necessary for managing the battery 31, such as the inter-terminal voltage signal from a voltage sensor 32 installed between the terminals of the battery 31, the charge / discharge current signal from a current sensor 33 attached to the power line connected to the output terminal of the battery 31, and the battery temperature signal from a temperature sensor 34 attached to the battery 31. It transmits data regarding the state of the battery 31 to the HEV_ECU4 via communication as needed. In addition, to manage the battery 31, the battery ECU3 calculates the state of charge (SOC), which is the ratio of the amount of power that can be discharged from the battery 31 at that time to the total capacity, based on the integrated value of the charge / discharge current detected by the current sensor 33, and calculates the input / output limits Win and Wout, which are the allowable input / output power for charging and discharging the battery 31, based on the calculated SOC and battery temperature.

[0016] The HEV_ECU4 controls the entire vehicle. Specifically, the HEV_ECU4 receives, via the input ports, a connection detection signal for detecting the connection of the power plug of a charger (a device connected to an external power source such as a household power supply to charge the battery 31) to the external power source, an ON / OFF signal from the start switch, a shift position signal from the shift position sensor, an accelerator opening signal from the accelerator pedal position sensor, a brake pedal position signal from the brake pedal position sensor, a vehicle speed signal from the vehicle speed sensor, etc. As described above, the HEV_ECU4 is connected to the engine ECU1, the motor ECU2, and the battery ECU3 via communication ports to exchange various control signals and data, and is also connected to the navigation device 5 via a communication port so that navigation information (such as the destination information and the current location information of the vehicle) can be received.

[0017] In addition, the HEV_ECU4 controls the driving mode of the vehicle. Specifically, in the vehicle according to the present embodiment, the driving modes include driving in a hybrid mode (HEV mode) and an electric mode (BEV mode). The HEV mode is a driving mode in which at least the engine 11 is used as a driving power source for driving. The BEV mode is a driving mode in which the engine 11 is stopped and only the motor generator (driving motor) MG2 is used as a driving power source for driving. Since the switching control between these HEV mode and BEV mode is well-known, the description thereof is omitted here.

[0018] When the state of charge (SOC) of the battery of the battery 31 drops to a predetermined value (the SOC required for the operation of the internal combustion engine in the present invention), the HEV_ECU4 transmits an engine operation command signal to the engine ECU1 on the condition that the engine 11 is operated. As a result, the motor generator MG1 generates power using the power of the engine 11, and the battery 31 is charged.

[0019] When a destination is set by the occupant, the navigation device 5 sets a driving route and provides route guidance. Specifically, the navigation device 5 includes a main body with a built-in control unit having a storage medium such as a hard disk storing map information and the like, an input / output port, a communication port, etc., a GPS antenna 51 that receives information regarding the current location of the vehicle, and a touch panel type display (not shown) that displays various information such as the information regarding the current location of the vehicle and the driving route to the destination and enables input of various instructions by the operator. When a destination is set by the occupant, the navigation device 5 searches for a driving route from the current location of the vehicle to the destination based on the map information, the current location of the vehicle, and the destination, and outputs the searched driving route to the display to provide route guidance. The navigation device 5 communicates with the HEV_ECU 4 and is capable of transmitting information regarding the current location of the vehicle, distance information to the destination, etc. to the HEV_ECU 4.

[0020] In addition, in the navigation device 5, a plurality of points including the occupant's home, etc. (for example, points set as destinations in the past, etc.) are associated with the time from the time when the vehicle stopped (for example, when the start switch was turned OFF) to the time when the vehicle started (for example, when the start switch was turned ON) at those points (vehicle stop duration: so-called, time until the next trip) and stored. In this case, when the vehicle stops and starts multiple times at the same point, the average value of each vehicle stop duration is stored as the vehicle stop duration associated with that point.

[0021] Next, the cooling water circuit mounted on the vehicle according to the present embodiment will be described. FIG. 2 is a diagram showing an outline of the cooling water circuit 6. The cooling water circuit 6 in the present embodiment includes a heater unit circuit 61 provided with a heater unit 61a of the air conditioner and a battery circuit 62 provided with a battery 31, and is configured such that the refrigerants (cooling water) circulating through these circuits 61 and 62 can exchange heat with each other through a heat exchanger 63.

[0022] The heater unit circuit 61 generally includes a water pump 61b, an engine 11, a water heater (electric heater) 61c, a flow control valve 61d, a heater unit 61a, and a heat exchanger 63. The heater unit 61a is installed in the duct of an air conditioning system (not shown) and contributes to heating the cabin by exchanging heat between the coolant (engine coolant circulating through the heater unit circuit 61: hot water) and the air (air supplied to the cabin through the duct). The water heater 61c is an electric heater for heating the engine coolant (internal combustion engine coolant) flowing through the heater unit circuit 61 and is turned ON when the engine coolant temperature drops to a predetermined value when heating is required in the cabin. In the heater unit circuit 61, the flow rate of the engine coolant flowing through the heater unit 61a and the flow rate of the engine coolant flowing through the heat exchanger 63 can be adjusted by flow control valve 61d. Furthermore, the heater unit circuit 61 has a water temperature sensor 13 located downstream of the water heater 61c. The location of the water temperature sensor 13 is not limited to this, and there may be multiple locations for the water temperature sensor 13. Also, although Figure 2 shows the water heater 61c and the engine 11 connected in series, it is not limited to this configuration. For example, they may be connected in parallel.

[0023] The battery circuit 62 is a circuit for regulating the temperature of the battery 31 and includes a water pump 62a. The battery circuit 62 is connected to a heat exchanger 63, and heat exchange in this heat exchanger 63 enables it to receive heat from the heater unit circuit 61.

[0024] The vehicle according to this embodiment is equipped with an air conditioning ECU 7 that controls the air conditioning inside the vehicle. This air conditioning ECU 7 is also configured as a microprocessor centered on a CPU, and in addition to the CPU, it is equipped with a ROM for storing processing programs, RAM for temporarily storing data, input / output ports, communication ports, etc.

[0025] The air conditioning ECU 7 controls each component in the cooling water circuit 6. For example, when a heating request is made in the passenger compartment, the air conditioning ECU 7 calculates the required amount of heat (requested heat) in response to the heating request, and also calculates the amount of heat received by the engine cooling water from the engine 11. Based on these calculations, it controls the water pump 61b, water heater 61c, etc., to ensure that heating is performed according to the requested heat.

[0026] A feature of the HEV_ECU4 in this embodiment is the process of setting the internal combustion engine operation request SOC to a lower value and activating the water heater 61c when both of the following conditions (1) and (2) are met while driving in HEV mode. together It is set to execute. Condition (1) The outside air temperature is below a specified value. That is thing, Condition (2) The distance to the vehicle's destination is less than or equal to a specified distance. and The estimated time until the next start after the vehicle has stopped is longer than the specified time. That is thing.

[0027] The ambient temperature parameter included in condition (1) is obtained from the ambient temperature sensor 14. .Ma Furthermore, the distance to the destination of the vehicle included in condition (2) is calculated from the navigation information (vehicle destination information and current location information) from the navigation device 5. Alternatively, the distance to the destination calculated by the navigation device 5 may be used as is. In addition, the predicted time until the next start after the vehicle has stopped is predicted based on the vehicle stop duration stored corresponding to each of the multiple points, as described above. It should be noted that the method for predicting this time until the next start is not limited to this, and various methods can be employed.

[0028] The procedure for controlling the reduction in engine operating frequency will be explained below using the flowchart in Figure 3. This flowchart describes the case where, while driving in HEV mode, both the process of setting the internal combustion engine operation request SOC low and the process of activating the water heater 61c are performed, provided that the ambient temperature is below a predetermined value, the distance to the vehicle's destination is below a predetermined distance, and the predicted time until the next start (next trip) after the vehicle has stopped is greater than or equal to a predetermined time.

[0029] First, in step ST1, it is determined whether the current driving mode is HEV mode or not. This determination is made based on control signals output from HEV_ECU4 to engine ECU1 and motor ECU2.

[0030] If the current driving mode is not HEV mode and step ST1 is judged as NO, the system returns to the previous state. On the other hand, if the current driving mode is HEV mode and step ST1 is judged as YES, the system proceeds to step ST2, where it is determined whether the outside air temperature is below a predetermined value Te1.

[0031] If the outside temperature exceeds a predetermined value Te1 and the result in step ST2 is NO, the system returns to the previous state. On the other hand, if the outside temperature is less than or equal to the predetermined value Te1 and the result in step ST2 is YES, the system proceeds to step ST3, where it is determined whether the distance to the destination in the current trip is less than or equal to a predetermined distance L1.

[0032] If the distance to the destination on the current trip exceeds a predetermined distance L1, and step ST3 is judged as NO, the system returns. On the other hand, if the distance to the destination on the current trip is less than or equal to the predetermined distance L1, and step ST3 is judged as YES, the system proceeds to step ST4, where it is determined whether the predicted time until the next trip is greater than or equal to a predetermined time Ti1. Note that the aforementioned predetermined values ​​(thresholds) Te1, L1, and Ti1 are set in advance through experiments and simulations.

[0033] If the predicted time until the next trip is less than the predetermined time Ti1 and the result in step ST4 is NO, the system returns. On the other hand, if the predicted time until the next trip is greater than or equal to the predetermined time Ti1 and the result in step ST4 is YES, the system proceeds to step ST5, where it performs the process of setting the internal combustion engine operation request SOC lower and activating the water heater 61c. The amount by which the internal combustion engine operation request SOC is reduced in this case is predetermined through experiments and simulations. The amount of heat generated by the water heater 61c in this case is predetermined through experiments and simulations as a value corresponding to the magnitude of the heating request in the vehicle cabin (the magnitude of the heating request according to the difference between the current vehicle cabin temperature and the target temperature) and the current SOC, etc.

[0034] Thus, in situations where it is not necessary to keep the battery 31's SOC high, the frequency of engine 11 operation is reduced by performing processes to lower the internal combustion engine operation request SOC or by activating the water heater 61c. The above operations are repeated.

[0035] As explained above, in this embodiment, during driving in HEV mode, condition (1) outside air temperature is below a predetermined value. That is Condition (2) The distance to the vehicle's destination is less than or equal to a specified distance. and The estimated time until the next start after the vehicle has stopped is longer than the specified time. That is If both of the above conditions are met, the process of setting the internal combustion engine operating requirement SOC to a lower value and the process of activating the water heater 61c are performed. together We are implementing this. This will reduce the frequency of engine 11 operation and improve fuel consumption.

[0036] Furthermore, the present invention is not limited to the embodiments described above, and all modifications and applications are possible within the scope of the claims and equivalents thereof.

[0037] For example, the above embodiment described the case in which the present invention is applied to a plug-in hybrid vehicle. However, the present invention is not limited to this and can also be applied to hybrid electric vehicles (HEVs). [Industrial applicability]

[0039] The present invention is applicable as a measure to reduce the frequency of engine operation in a vehicle equipped with an engine and a traction motor as a driving force source. [Explanation of symbols]

[0040] 4…HEV_ECU (Vehicle Control Unit) 11…Engine (Internal Combustion Engine) MG1, MG2…Motor generator (electric motor) 61c…Water heater

Claims

[Claim 1] A vehicle control device mounted on a vehicle that is equipped with an internal combustion engine and an electric motor as driving power sources for propulsion, and a water heater as a heat source for heating the vehicle interior, and which operates the internal combustion engine on the condition that the State of Charge (SOC) of the battery supplying power to the electric motor drops to the SOC required for operation of the internal combustion engine, A vehicle control device characterized in that, during driving in HEV mode using at least the internal combustion engine as the driving force source, when both of the following conditions (1) and (2) are met, it performs both a process to set the internal combustion engine operation request SOC to a low value and a process to activate the water heater. Condition (1) The outside air temperature is below a specified value. Condition (2) The distance to the vehicle's destination is less than or equal to a predetermined distance, and the estimated time until the next start after the vehicle has stopped is greater than or equal to a predetermined time.

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