Vehicle control device

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, and more particularly to a measure for reducing the operation frequency of an internal combustion engine in a vehicle equipped with an internal combustion engine and an electric motor as a driving force source for traveling. [Background technology]

[0002] Conventionally, vehicles such as hybrid vehicles and plug-in hybrid vehicles are known that are equipped with an internal combustion engine (hereinafter sometimes referred to as an engine) and an electric motor (hereinafter sometimes referred to as a traction motor) as a driving power source for traveling. In this type of vehicle, when traveling in a so-called hybrid mode (HEV mode), if the SOC (State Of Charge) of a traction battery (hereinafter sometimes referred to as a battery) that supplies power to the traction motor drops to a predetermined value, the engine is operated to charge the battery. Also, if there is a request to heat the passenger compartment, the engine is controlled to be turned on / off according to the engine coolant temperature. That is, when the engine coolant temperature drops to a predetermined value, the engine is operated to increase the engine coolant temperature.

[0003] Patent Document 1 proposes an example of engine ON / OFF control according to engine coolant temperature. Patent Document 1 discloses that in a vehicle equipped with an engine and an auxiliary heater as a heat source for heating, when the auxiliary heater is not being used and the engine coolant temperature is equal to or lower than a threshold value that is preset according to a target outlet temperature, normal engine start request control is performed to prevent a drop in the engine coolant temperature, while when the auxiliary heater is being used, power-saving engine ON request control is performed with a water temperature threshold value that is lower than the water temperature threshold value in the normal engine start request control, thereby extending the engine stop time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-308133 A Summary of the Invention [Problem to be solved by the invention]

[0005] The inventors of the present invention have considered measures to further improve the fuel consumption rate, in consideration of the fact that there is a limit to improving the fuel consumption rate when the engine is simply controlled to be turned on and off according to the battery SOC or the engine coolant temperature as described above. For example, they focused on the current situation in which the engine operates in response to a warm-up request during a cold start, and if the engine is operating just before arriving at the destination in the previous trip, the engine operation frequency increases doubly, resulting in a deterioration in the total fuel consumption rate. In other words, the inventors of the present invention focused on the fact that the engine is controlled simply according to the battery SOC or the engine coolant temperature regardless of the vehicle's running conditions (distance to the destination, etc.), and obtained new knowledge that there is room for improvement in the fuel consumption rate in such a situation, leading to the present invention.

[0006] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide a vehicle control device that is capable of reducing the operating frequency of the engine and improving the fuel consumption rate. [Means for solving the problem]

[0007] The solution of the present invention for achieving the above object is based on a vehicle control device mounted on a vehicle that includes an internal combustion engine and an electric motor as a driving force source for driving, a water heater as a heat source for heating the vehicle interior, and operates the internal combustion engine on condition that the SOC of a battery that supplies power to the electric motor drops to an internal combustion engine operation requirement SOC. This vehicle control device is characterized in that, when driving in an HEV mode using at least the internal combustion engine as the driving force source for driving, and when both of the following conditions (1) and (2) are satisfied, the vehicle control device executes at least one of a process of setting the internal combustion engine operation requirement SOC low and a process of operating the water heater. Condition (1) At least one of the outside air temperature being equal to or lower than a predetermined value and the internal combustion engine coolant temperature being equal to or lower than a predetermined value is satisfied. Condition (2) At least one of the following is satisfied: the distance to the vehicle's destination is less than a predetermined distance, and the predicted time until the next start of the vehicle after it has stopped is greater than or equal to a predetermined time.

[0008] With this specification, in a situation where there is a high possibility of a demand for heating the vehicle cabin, and the distance to the vehicle's destination is less than a predetermined distance or the predicted time until the next start after the vehicle is stopped is more than a predetermined time, and there is no need to keep the battery SOC high, the internal combustion engine operation demand SOC can be set low or the water heating heater can be operated, thereby reducing the operation frequency of the internal combustion engine and improving fuel consumption. Effect of the Invention

[0009] In the present invention, when the following conditions are met during driving in HEV mode: (1) at least one of the outside air temperature being equal to or lower than a predetermined value and the internal combustion engine coolant temperature being equal to or lower than a predetermined value, and (2) at least one of the following is met: the distance to the vehicle's destination is equal to or lower than a predetermined distance and the predicted time until the next start after the vehicle is stopped is equal to or longer than a predetermined time, at least one of the process of setting the internal combustion engine operation requirement SOC low and the process of operating the water heater is executed. This makes it possible to reduce the operation frequency of the internal combustion engine and improve the fuel consumption rate. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an outline of a control system for a vehicle according to an embodiment; [Diagram 2] 1 is a diagram showing an outline of a coolant circuit mounted on a vehicle according to an embodiment; [Diagram 3] FIG. 4 is a flowchart showing a procedure for engine operation frequency reduction control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as being applied to a plug-in hybrid vehicle (PHEV).

[0012] Fig. 1 is a diagram showing an outline of a control system of a vehicle according to this embodiment. As shown in Fig. 1, the control system of the vehicle 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 around a CPU, and include, in addition to the CPU, 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 device 5.

[0013] The engine ECU 1 controls the operation of an engine (internal combustion engine) 11 as a driving force source for traveling. 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 a crank position sensor 12, an engine coolant temperature (internal combustion engine coolant temperature) signal from a water temperature sensor 13, an outside air temperature signal from an outside air temperature sensor 14, etc.) via an input port, and outputs various control signals for driving the engine 11 from the engine ECU 1 via an output port. The engine ECU 1 also communicates with an HEV_ECU 4, controls the operation of the engine 11 according to control signals from the HEV_ECU 4, and outputs data related to the operating state of the engine 11 to the HEV_ECU 4 as necessary.

[0014] The motor ECU 2 controls two motor generators (electric motors) MG1, MG2 (a first motor generator MG1 that mainly functions as a generator, and a second motor generator MG2 that mainly functions as an electric motor) by switching control of an inverter (not shown). Specifically, signals required to control the motor generators MG1, MG2 are input to the motor ECU 2 via an input port, and switching control signals and the like to switching elements (not shown) of the inverter are output from the motor ECU 2 via an output port. The motor ECU 2 also communicates with the HEV_ECU 4, and controls the motor generators MG1, MG2 by control signals from the HEV_ECU 4, and outputs data relating to the operating states of the motor generators MG1, MG2 to the HEV_ECU 4 as necessary.

[0015] The battery ECU 3 manages the battery 31, which is configured as, for example, a lithium-ion secondary battery. The battery 31 exchanges power with the motor generators MG1 and MG2 via an inverter. Specifically, the battery ECU 3 receives signals necessary for managing the battery 31, such as a terminal voltage signal from a voltage sensor 32 installed between the terminals of the battery 31, a charge / discharge current signal from a current sensor 33 attached to a power line connected to an output terminal of the battery 31, and a battery temperature signal from a temperature sensor 34 attached to the battery 31, and transmits data on the state of the battery 31 to the HEV_ECU 4 by communication as necessary. In addition, in order to manage the battery 31, the battery ECU 3 calculates a power storage ratio SOC, which is a ratio of the capacity of power that can be discharged from the battery 31 at that time to the total capacity, based on an integrated value of the charge / discharge current detected by the current sensor 33, and calculates input / output limits Win and Wout, which are allowable input / output power that may be charged and discharged from the battery 31, based on the calculated power storage ratio SOC and the battery temperature.

[0016] The HEV_ECU 4 controls the entire vehicle. Specifically, the HEV_ECU 4 receives, via an input port, a connection detection signal for detecting connection of a power plug of a charger (a device connected to an external power source such as a household power source to charge the battery 31) (not shown) to an external power source, an ON / OFF signal from a start switch, a shift position signal from a shift position sensor, an accelerator opening signal from an accelerator pedal position sensor, a brake pedal position signal from a brake pedal position sensor, a vehicle speed signal from a vehicle speed sensor, and the like. As described above, the HEV_ECU 4 is not only connected to the engine ECU 1, the motor ECU 2, and the battery ECU 3 via communication ports to exchange various control signals and data, but is also connected to the navigation device 5 via a communication port to receive navigation information (such as vehicle destination information and current location information).

[0017] The HEV_ECU4 also controls the driving mode of the vehicle. Specifically, the vehicle according to this embodiment can run in a hybrid mode (HEV mode) or an electric mode (BEV mode) as the driving mode. The HEV mode is a driving mode in which the vehicle runs using at least the engine 11 as a driving power source for running. The BEV mode is a driving mode in which the engine 11 is stopped and the vehicle runs using only the motor generator (driving motor) MG2 as a driving power source for running. The switching control between the HEV mode and the BEV mode is well known, so a description thereof will be omitted here.

[0018] Furthermore, when the SOC (electricity storage ratio SOC) of the battery 31 falls to a predetermined value (internal combustion engine operation requirement SOC in the present invention), the HEV_ECU 4 transmits an engine operation command signal to the engine ECU 1 to operate the engine 11 under that condition. As a result, the motor generator MG1 using the power of the engine 11 generates electricity to charge the battery 31.

[0019] The navigation device 5 sets a travel route and provides route guidance when a destination is set by the occupant. Specifically, the navigation device 5 includes a main body incorporating a control unit having a storage medium such as a hard disk on which map information and the like is stored, an input / output port, a communication port, and the like, a GPS antenna 51 that receives information about the current location of the vehicle, and a touch panel display (not shown) that displays various information such as information about the current location of the vehicle and a travel route to the destination and allows an operator to input various instructions. When a destination is set by the occupant, the navigation device 5 searches for a travel 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 travel route to the display to provide route guidance. The navigation device 5 communicates with the HEV_ECU 4 and is capable of transmitting information about the current location of the vehicle and information about the distance to the destination to the HEV_ECU 4.

[0020] Furthermore, the navigation device 5 stores a plurality of points (e.g., points previously set as destinations) including the occupant's home, in association with the time from when the vehicle stopped (e.g., the start switch was turned OFF) at each of the points to when the vehicle started (e.g., the start switch was turned ON) (vehicle stop duration: so-called time until the next trip). In this case, if the vehicle is stopped and started multiple times at the same point, the average value of each vehicle stop duration is stored as the vehicle stop duration associated with the point.

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

[0022] The heater unit circuit 61 generally includes a water pump 61b, the engine 11, a water heater (electric heater) 61c, a flow rate control valve 61d, a heater unit 61a, and a heat exchanger 63. The heater unit 61a is disposed in a duct of an air conditioner (not shown) and exchanges heat between the coolant (engine coolant: warm water circulating through the heater unit circuit 61) and air (air supplied to the passenger compartment through the duct) to heat the air and contribute to heating the passenger compartment. 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 to heat the engine coolant when the engine coolant temperature drops to a predetermined value when heating of the passenger compartment is required. 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 rate control using the flow rate control valve 61d. Additionally, the heater unit circuit 61 has a water temperature sensor 13 disposed downstream of the water heater 61c. The location of the water temperature sensor 13 is not limited thereto, and the water temperature sensor 13 may be disposed at a plurality of locations. Additionally, while FIG. 2 shows the water heater 61c and the engine 11 connected in series, the present invention is not limited thereto. For example, they may be connected in parallel.

[0023] The battery circuit 62 is a circuit for adjusting the temperature of the battery 31, and includes a water pump 62a. The battery circuit 62 is connected to a heat exchanger 63, and is capable of receiving heat from the heater unit circuit 61 by heat exchange in the heat exchanger 63.

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

[0025] The air conditioner ECU 7 controls each device provided in the coolant circuit 6. For example, when a request for heating the vehicle interior occurs, the air conditioner ECU 7 calculates the amount of heat required in response to the heating request (requested amount of heat), calculates the amount of heat received by the engine coolant from the engine 11, and controls the water pump 61b, the water heater 61c, etc. based on the calculation results to perform heating according to the requested amount of heat.

[0026] A characteristic function of the HEV_ECU4 in this embodiment is to execute at least one of a process of setting the internal combustion engine operation requirement SOC low and a process of operating the water heating heater 61c when both of the following conditions (1) and (2) are satisfied while driving in HEV mode. Condition (1) At least one of the following is satisfied: the outside air temperature is equal to or lower than a predetermined value and the engine coolant temperature is equal to or lower than a predetermined value; Condition (2) At least one of the following is satisfied: the distance to the vehicle's destination is less than a predetermined distance, and the predicted time until the next start of the vehicle after it has stopped is greater than or equal to a predetermined time.

[0027] The parameter outside air temperature included in condition (1) is obtained from the outside air temperature sensor 14. Moreover, the engine coolant temperature is obtained from the water temperature sensor 13. Moreover, the distance to the destination of the vehicle included in condition (2) is calculated from navigation information (vehicle destination information and current location information) from the navigation device 5. Moreover, the information on the distance to the destination calculated in the navigation device 5 may be used as is. Moreover, the predicted time until the next start after the vehicle is stopped is predicted based on the vehicle stop duration stored corresponding to each of the multiple points, as described above. However, the method for predicting the time until the next start is not limited to this, and various methods can be adopted.

[0028] The procedure for the engine operation frequency reduction control will be described below with reference to the flowchart in Fig. 3. This flowchart describes a case where, during driving in HEV mode, the process of setting the internal combustion engine operation requirement SOC low and the process of operating the water heater 61c are both performed under the conditions that the outside air temperature is equal to or lower than a predetermined value, the distance to the vehicle's destination is equal to or shorter than a predetermined distance, and the predicted time until the next start (next trip) after the vehicle is stopped is equal to or longer than a predetermined time.

[0029] First, in step ST1, it is determined whether the current driving mode is the HEV mode. This determination is made based on control signals output from the HEV_ECU 4 to the engine ECU 1 and the motor ECU 2.

[0030] If the current driving mode is not the HEV mode and the determination in step ST1 is NO, the process returns. On the other hand, if the current driving mode is the HEV mode and the determination in step ST1 is YES, the process proceeds to step ST2, where it is determined whether the outside air temperature is equal to or lower than a predetermined value Te1.

[0031] If the outside air temperature exceeds the predetermined value Te1 and the determination in step ST2 is NO, the process returns directly. On the other hand, if the outside air temperature is equal to or lower than the predetermined value Te1 and the determination in step ST2 is YES, the process proceeds to step ST3, where it is determined whether the distance to the destination in the current trip is equal to or shorter than a predetermined distance L1.

[0032] If the distance to the destination in the current trip exceeds the predetermined distance L1 and the determination in step ST3 is NO, the process returns. On the other hand, if the distance to the destination in the current trip is equal to or less than the predetermined distance L1 and the determination in step ST3 is YES, the process proceeds to step ST4, where it is determined whether the predicted time until the next trip is equal to or more than the predetermined time Ti1. The above-mentioned predetermined values ​​(threshold values) Te1, L1, and Ti1 are preset by experiments or simulations.

[0033] If the predicted time until the next trip is less than the predetermined time Ti1 and the determination in step ST4 is NO, the process returns. On the other hand, if the predicted time until the next trip is equal to or greater than the predetermined time Ti1 and the determination in step ST4 is YES, the process proceeds to step ST5, where the process of setting the internal combustion engine operation requirement SOC low and the process of operating the water heating heater 61c are performed. The amount of reduction in the internal combustion engine operation requirement SOC in this case is preset through experiments and simulations. Also, the heat generation amount of the water heating heater 61c in this case is preset through experiments and simulations as a value corresponding to the magnitude of the heating requirement in the vehicle cabin (the magnitude of the heating requirement corresponding to the difference between the current vehicle cabin temperature and the target temperature) and the current SOC, etc.

[0034] In this way, in a situation where it is not necessary to keep the SOC of the battery 31 high, the internal combustion engine operation requirement SOC is set low and the water heater 61c is operated, thereby reducing the operation frequency of the engine 11. The above operations are repeated.

[0035] As described above, in this embodiment, when the following conditions are met during driving in the HEV mode: (1) the outside air temperature is equal to or lower than a predetermined value and the engine coolant temperature is equal to or lower than a predetermined value, and (2) the distance to the vehicle's destination is equal to or lower than a predetermined distance and the predicted time until the next start after the vehicle is stopped is equal to or longer than a predetermined time, at least one of the process of setting the internal combustion engine operation requirement SOC low and the process of operating the water heater 61c is executed. This makes it possible to reduce the operation frequency of the engine 11 and improve the fuel consumption rate.

[0036] The present invention is not limited to the above-described embodiment, and all modifications and applications within the scope of the claims and equivalents thereto are possible.

[0037] For example, in the above embodiment, the present invention has been described as being applied to a plug-in hybrid vehicle, but the present invention is not limited to this and can also be applied to a hybrid vehicle (HEV).

[0038] In the above embodiment, a case has been described in which, during driving in the HEV mode, the process of setting the internal combustion engine operation request SOC low and the process of operating the water heating heater 61c are both performed under the conditions that the outside air temperature is equal to or lower than a predetermined value, the distance to the vehicle's destination is equal to or lower than a predetermined distance, and the predicted time until the next start after the vehicle is stopped is equal to or higher than a predetermined time. The present invention is not limited to this, and it is sufficient that, during driving in the HEV mode, when both the condition (1) and the condition (2) are satisfied, at least one of the process of setting the internal combustion engine operation request SOC low and the process of operating the water heating heater 61c is executed. [Industrial Applicability]

[0039] The present invention is applicable as a measure for reducing the frequency of engine operation in a vehicle that has an engine and a traction motor as a source of driving power for traveling. [Explanation of symbols]

[0040] 4...HEV_ECU (vehicle control device) 11...Engine (internal combustion engine) MG1, MG2: Motor generator (electric motor) 61c: Water heater

Claims

[Claim 1] A vehicle control device is mounted on a vehicle that includes an internal combustion engine and an electric motor as a driving force source for traveling, and a water heater as a heat source for heating a vehicle interior, and that operates the internal combustion engine on the condition that an SOC of a battery that supplies power to the electric motor drops to an SOC required for operating the internal combustion engine, A vehicle control device characterized in that, during driving in an HEV mode in which at least the internal combustion engine is used as the driving power source for driving, when both of the following conditions (1) and (2) are satisfied, at least one of a process of setting the internal combustion engine operation required SOC low and a process of operating the water heating heater is executed. Condition (1) At least one of the outside air temperature being equal to or lower than a predetermined value and the internal combustion engine coolant temperature being equal to or lower than a predetermined value is satisfied. Condition (2) At least one of the following is satisfied: the distance to the vehicle's destination is less than a predetermined distance, and the predicted time until the next start of the vehicle after it has stopped is greater than or equal to a predetermined time.

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