Control method for hybrid vehicle and control device for hybrid vehicle

Abstract

According to the present invention, a control method for a hybrid vehicle that comprises an engine and an electric heater for air-conditioning involves calculating a target heat dissipation amount that is a target amount for heat dissipation by the engine and the electric heater, calculating the amount of heat dissipation by the engine on the basis of the operating state of the engine, calculating a heat dissipation insufficiency amount relative to the target heat dissipation amount on the basis of the target heat dissipation amount and the heat dissipation amount of the engine, and controlling the electric heater on the basis of the heat dissipation insufficiency amount.

Description

Control Method for Hybrid Vehicle and Control Device for Hybrid Vehicle

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

[0002] A control method for a hybrid vehicle that uses heat dissipation from an engine and an electric heater for cabin heating is known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2015-74408

[0004] In the control method for a hybrid vehicle described in Patent Document 1, based on the remaining power of the battery and the cooling water temperature of the engine, a heat pump system as an electric heater is controlled. Therefore, even when sufficient heat dissipation can be obtained only from the exhaust heat of the engine, the electric heater continues to be used and the generated power may become excessive, which may reduce the fuel efficiency of the engine.

[0005] An object of the present invention is to provide a control method for a hybrid vehicle and a control device for a hybrid vehicle that can suppress a decrease in the fuel efficiency of the engine due to heating.

[0006] One aspect of the present invention calculates a shortage heat dissipation amount with respect to a target heat dissipation amount based on the target heat dissipation amount, which is the target value of the heat dissipation amount by the engine and the air-conditioning electric heater of the hybrid vehicle, and the heat dissipation amount of the engine, and controls the electric heater based on the shortage heat dissipation amount.

[0007] It is a schematic configuration diagram of a vehicle. It is a diagram showing a cooling circuit for cooling the cooling water of the engine. It is a block diagram of a control device for a vehicle. It is a flowchart of a control method for a vehicle. It is a diagram showing the relationship between the power consumption, generated power, and charging power of the vehicle and the heat dissipation amount of each of the engine and the electric heater.

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a vehicle 10. The vehicle 10 is a so-called series hybrid vehicle that supplies power generated by a generator 3 with the power of an engine 31 to a battery 21 and drives wheels 25 to travel by rotating an electric motor 23 with the power of the battery 21.

[0009] The vehicle 10 is equipped with a drive unit 20, a power generator 30, an air conditioning unit 40, and a control device 50.

[0010] The drive unit 20 comprises a battery 21, an inverter 22, an electric motor 23, a reduction gear 24, and wheels 25. The inverter 22 converts the direct current input from the battery 21 into alternating current and outputs it to the electric motor 23. The inverter 22 also converts the alternating current input from the electric motor 23 into direct current and inputs it to the battery 21. The electric motor 23 is driven according to the input from the inverter 22 and generates the driving force and regenerative braking force of the vehicle 10. The reduction gear 24 comprises a transmission 24A and a differential gear 24B, and reduces the output of the electric motor 23 and transmits it to the wheels 25.

[0011] The power generation device 30 includes an engine 31, a speed increaser 32, a generator 33, and an inverter 34.

[0012] The engine 31 is mechanically connected to the generator 33 via a speed increaser 32. The engine 31 is used not as a power source to drive the vehicle 10, but as a power source to drive the generator 33 and generate electricity. When the engine 31 is started, the engine 31 is warmed up by command from the engine controller 31A, and when the warm-up is complete, the engine controller 31A outputs a warm-up completion signal. The engine controller 31A also outputs the torque and rotational speed of the engine 31.

[0013] The generator 33 is configured to generate electricity by rotating using power from the engine 31, and to charge the battery 21. The generator 33 can use the power from the battery 21 to rotate the output shaft of the engine 31 to crank it when starting the engine 31, to perform motoring by rotating the engine 31 as a load to consume power when the State of Charge (SOC) of the battery 21 is high, and to close the throttle valve of the engine 31 to generate negative pressure in the intake passage when negative pressure is needed for brake pedal assist.

[0014] The air conditioning system 40 is a device that provides air conditioning for the interior of the vehicle 10, including heating, cooling, and ventilation. The air conditioning system 40 supplies warm air to the interior by blowing air into a circulation path of cooling water, which is heated by the engine 31. The air conditioning system 40 includes an air conditioning control unit 41, an HVAC (Heating-Ventilation-Air Conditioning) unit 42, and a cooling circuit 43.

[0015] The air conditioning control unit 41 is equipped with, for example, operating devices such as a touch panel, various buttons, and various switches, and is configured to allow operations such as switching between heating, cooling, and ventilation in the vehicle 10's interior, and changing the set temperature of the air conditioning.

[0016] The HVAC 42 supplies warm or cool air to the room in response to operations performed on the air conditioning control unit 41. Information about operations performed on the air conditioning control unit 41 (hereinafter referred to as air conditioning operation information) is output from the HVAC 42 to the control device 50. The air conditioning operation information includes, for example, the set temperature of the air conditioning. If the set temperature during heating is higher than the room temperature, or if the set temperature during heating is increased, and it is necessary to raise the coolant temperature, the HVAC 42 outputs a signal requesting a rise in coolant temperature due to heating to the HVAC 42 and the control device 50. The HVAC 42 and the engine 31 are connected by a cooling circuit 43 that circulates between them.

[0017] Figure 2 shows a cooling circuit 43. The cooling circuit 43 circulates coolant to cool the engine 31 and other components. The coolant is also supplied to the throttle chamber 44, which includes a throttle valve for adjusting the intake volume of the engine 31, the turbocharger 45, the EGR cooler 46, and the oil cooler 47 of the engine 31.

[0018] The cooling circuit 43 includes a first pump 43A, a second pump 43B, a valve 43C, a PTC (Positive Temperature Coefficient) heater 43D as an electric heater for air conditioning, an indoor heater 43E, a radiator 43F, a bypass passage 43G, and a thermostat 43H.

[0019] Pumps 43A and 43B, valve 43C, and PTC heater 43D are controlled by the control device 50.

[0020] Valve 43C is provided to switch the circuit within the cooling circuit 43. When valve 43C is turned on, the coolant heated by the engine 31 and PTC heater 43D passes through the cabin heater 43E and warm air is supplied to the cabin.

[0021] Returning to Figure 1, the control device 50 includes a room temperature sensor 60A, an outside temperature sensor 60B, and a controller 70.

[0022] The room temperature sensor 60A detects the room temperature of the vehicle 10.

[0023] The outside temperature sensor 60B detects the outside temperature of the vehicle 10.

[0024] Figure 3 is a control block diagram of the controller 70. The controller 70 controls the amount of heat dissipated by the engine 31 and the PTC heater 43D, as well as the electric motor 23 and the generator 33. The controller 70 is implemented by a computer equipped with, for example, a storage device 71 such as ROM (Read Only Memory) and RAM (Random Access Memory), an arithmetic unit 72 composed of a processor such as a CPU (Central Processing Unit) and a GPU (Central Graphics Processing Unit), and an input / output unit such as an input / output interface. The inverters 22 and 34, the engine controller 31A, the air conditioning unit 40, the room temperature sensor 60A, and the outside temperature sensor 60B are electrically or communicatively connected to the controller 70.

[0025] The storage device 71 stores computer programs for operating the controller 70, various maps used for control, and various parameter values. Maps stored in the storage device 71 include, for example, a target heat dissipation map that defines the relationship between the difference between the air conditioning set temperature and the room temperature, the outside temperature, and the target heat dissipation amount; an engine heat dissipation map that defines the relationship between the torque and rotational speed of the engine 31 and the heat dissipation amount of the engine 31; and a heater heat dissipation map that defines the relationship between the power of the PTC heater 43D and the heat dissipation amount of the PTC heater 43D. Parameter values ​​stored in the storage device 71 include, for example, the lower limit of the power of the PTC heater 43D during warm-up and various threshold values ​​used in control.

[0026] The calculation unit 72 includes a heating water temperature rise request determination unit 73, a target heat dissipation amount calculation unit 74, an engine heat dissipation amount calculation unit 75, a heat deficiency amount calculation unit 76, a warm-up completion determination unit 77, and an electric heater control unit 78.

[0027] The heating water temperature rise request determination unit 73 determines whether or not there is a request for a rise in the cooling water temperature due to heating, based on the air conditioning operation information and cooling water temperature rise request signal from the air conditioning unit 40.

[0028] The target heat dissipation calculation unit 74 calculates the target heat dissipation amount, which is the target value of the heat dissipation amount by the engine 31 and the PTC heater 43D. In this embodiment, the target heat dissipation calculation unit 74 calculates the target heat dissipation amount based on the difference between the air conditioning set temperature and the room temperature, and the outside temperature.

[0029] The engine heat dissipation calculation unit 75 calculates the amount of heat dissipated by the engine 31 based on the operating state of the engine 31. In this embodiment, the engine heat dissipation calculation unit 75 uses the torque and rotational speed of the engine 31 as the operating state of the engine 31 and calculates the amount of heat dissipated by the engine 31 based on the engine torque and engine rotational speed.

[0030] The heat deficiency calculation unit 76 calculates the heat deficiency relative to the target heat dissipation amount based on the target heat dissipation amount and the heat dissipation amount of the engine 31.

[0031] The warm-up completion determination unit 77 determines whether the warm-up of the engine 31 has been completed based on the warm-up completion signal.

[0032] The electric heater control unit 78 controls the PTC heater 43D based on the amount of insufficient heat dissipation. In this embodiment, the electric heater control unit 78 calculates the power of the PTC heater 43D required to generate the insufficient heat dissipation from the PTC heater 43D, and controls the PTC heater 43D by commanding the air conditioning system 40 to set the PTC heater 43D to that power. Furthermore, if the engine 31 has not finished warming up, the electric heater control unit 78 limits the power of the PTC heater 43D to the lower limit during warming up.

[0033] Figure 4 is a flowchart of the control method executed by the controller 70. The control routines shown in the flowchart are pre-programmed and installed in the controller 70. The controller 70 repeatedly executes the following control routines in calculation cycles of approximately 10 to 1000 milliseconds, according to the program.

[0034] In step S1 of Figure 4, the controller 70 acquires the outputs of the engine controller 31A, the air conditioning unit 40, and sensors 60A and 60B, namely engine torque, engine speed, warm-up completion signal, air conditioning operation information, cooling water temperature rise request signal due to heating, the room temperature of the vehicle 10, and the outside temperature.

[0035] In step S2, the heating water temperature rise request determination unit 73 determines whether or not there is a request for a rise in cooling water temperature due to heating, based on the air conditioning operation information and cooling water temperature rise request signal from the air conditioning unit 40. If it is determined in step S2 that there is no request for a rise in cooling water temperature due to heating, the control is terminated. If it is determined that there is a request for a rise in cooling water temperature due to heating, the process proceeds to step S3.

[0036] In step S3, the target heat dissipation calculation unit 74 calculates the target heat dissipation amount by the engine 31 and the PTC heater 43D. In this embodiment, the target heat dissipation calculation unit 74 uses a map that defines the relationship between the difference between the air conditioning set temperature and the room temperature, the outside temperature, and the target heat dissipation amount to calculate the target heat dissipation amount.

[0037] In step S4, the engine heat dissipation calculation unit 75 uses a map that defines the relationship between engine torque and engine speed and the amount of heat dissipated by the engine 31, and calculates the amount of heat dissipated by the engine 31 based on the engine torque and engine speed.

[0038] In step S5, the heat deficiency calculation unit 76 subtracts the heat dissipation amount of the engine 31 from the target heat dissipation amount to calculate the heat deficiency amount relative to the target heat dissipation amount.

[0039] In step S6, the electric heater control unit 78 uses a map that defines the relationship between the power of the PTC heater 43D and the amount of heat dissipated by the PTC heater 43D to calculate the power of the PTC heater 43D required to generate the insufficient amount of heat dissipation from the PTC heater 43D.

[0040] In step S7, the warm-up completion determination unit 77 determines whether the warm-up of the engine 31 has been completed based on the warm-up completion signal. If it is determined in step S7 that the warm-up has been completed, the electric heater control unit 78 outputs a command to the air conditioning unit 40 in step S8 to drive the PTC heater 43D with the power calculated in step S6, and drives the PTC heater 43D with said power.

[0041] On the other hand, if it is determined in step S7 that the warm-up is not yet complete, the electric heater control unit 78 limits the power of the PTC heater 43D calculated in step S6 to the lower limit value during warm-up, and outputs a command to the air conditioning unit 40 such that the PTC heater 43D is driven by the limited power.

[0042] Figure 5 shows the relationship between the power consumption, power generation, and power charging of the vehicle 10 and the heat dissipation amounts of the engine 31 and PTC heater 43D, respectively, for cases 1 to 5. The upper part of Figure 5 lists the power consumption, power generation, and power charging of the vehicle 10 from left to right. The lower part of Figure 5 lists the heat dissipation amounts of the engine 31 and PTC heater 43D, respectively. For simplicity of explanation, cases 1 to 5 are illustrated as examples where the target heat dissipation amount is the same.

[0043] In Case 1 of FIG. 5, fixed-point power generation is performed at the operating point where the power generation efficiency of the generator 33 is the highest by driving the engine 31, and the charging of the battery 21 is not restricted. In the case of Case 1, since the amount of exhaust heat of the engine 31 is large and the amount of insufficient heat dissipation with respect to the target heat dissipation amount is small, the power of the PTC heater 43D required to generate the insufficient heat dissipation amount can be small. Therefore, the controller 70 reduces the power of the PTC heater 43D in accordance with the amount of insufficient heat dissipation. If the power consumption of the vehicle 10 is less than the generated power, the remainder of the generated power is charged to the battery 21 by the controller 70.

[0044] Case 2 is a situation where the amount of charge to the battery 21 is restricted and it is necessary to reduce the generated power by the generator 33 below the fixed-point output. In Case 2, in order to reduce the output of the engine 31 in accordance with the reduction of the generated power, compared with the case of Case 1, the amount of exhaust heat of the engine 31 is small and the amount of insufficient heat dissipation with respect to the target heat dissipation amount increases. Therefore, the controller 70 increases the power of the PTC heater 43D more than in the case of Case 1. Even in this case, if the power consumption of the vehicle 10 is less than the generated power, the remainder of the generated power is charged to the battery 21.

[0045] Case 3 is a situation where the charging of the battery 21 is stopped and it is necessary to make the generated power by the generator 33 smaller than the fixed-point output. In Case 3, in order to reduce the output of the engine 31 in accordance with the reduction of the generated power, compared with the case of Case 2, the amount of exhaust heat of the engine 31 is even less and the amount of insufficient heat dissipation with respect to the target heat dissipation amount becomes even larger. Therefore, the controller 70 increases the power of the PTC heater 43D more than in the case of Case 2 and sets it to the maximum power as necessary.

[0046] Case 4 is a situation where power generation by the generator 33 is not performed and the engine 31 is stopped, such as when regenerative power continues. In Case 4, since no exhaust heat of the engine 31 occurs, the amount of insufficient heat dissipation becomes equal to the target heat dissipation amount. Therefore, the controller 70 increases the power of the PTC heater 43D so as to approach the target heat dissipation amount and sets it to the maximum power as necessary.

[0047] Case 5 is a situation where, as in high-load driving, the generated power by the generator 33 is large and the heat dissipation amount of the engine 31 exceeds the target heat dissipation amount. In Case 5, since the target heat dissipation amount can be obtained only by the heat dissipation of the engine 31 and the insufficient heat dissipation amount becomes zero, the controller 70 does not drive the PTC heater 43D.

[0048] According to the above-described embodiment, since the PTC heater 43D is controlled based on the target heat dissipation amount and the heat dissipation amount of the engine 31, when a sufficient heat dissipation amount can be obtained only by the exhaust heat of the engine 31, it is possible to prevent the generated power from becoming excessive by continuously using the PTC heater 43D, and suppress the decrease in the fuel consumption of the engine 31 due to heating.

[0049] According to the embodiment, when the warm-up of the engine 31 has not ended, since the power of the PTC heater 43D is limited to the lower limit value during warm-up, the heat dissipation amount of the PTC heater 43D can be increased during warm-up, and the temperature of the engine 31 and the room temperature of the vehicle 10 can be rapidly increased.

[0050] As described above, the best configuration, method, etc. for implementing the present invention are disclosed in the above description, but the present invention is not limited thereto. That is, the present invention is mainly illustrated and described with respect to specific embodiments, but without departing from the scope of the technical idea and purpose of the present invention, those skilled in the art can make various modifications to the above-described embodiments in terms of shape, material, quantity, and other detailed configurations. In addition, the descriptions that limit the shape, material, etc. disclosed above are exemplified for easy understanding of the present invention and do not limit the present invention. Therefore, the descriptions using the names of members with some or all of the limitations of those shapes, materials, etc. removed are included in the present invention.

[0051] The vehicle 10 may be a parallel hybrid vehicle, and the wheels 25 may be driven by the electric motor 23 and the engine 31. The vehicle 10 may be an all-wheel drive vehicle, a front-wheel drive vehicle, or a rear-wheel drive vehicle.

[0052] The transmission 24A may have a fixed gear ratio, be configured to allow stepwise switching between multiple gear ratios, or be configured to allow continuous switching of gear ratios, such as a CVT (Continuously Variable Transmission).

[0053] The air conditioning system 40 does not necessarily have a PTC heater 43D in its cooling circuit 43; it may also use heated air that has passed around the PTC heater 43D to be introduced into the interior of the vehicle 10 for heating. The air conditioning system 40 may also be equipped with electric heaters other than the PTC heater 43D.

[0054] The controller 70 may use the electric motor 23 as an electric heater by supplying a d-axis current to the electric motor 23 and transferring the heat generated by the d-axis discharge to the cooling water in the cooling circuit 43. The controller 70 may also obtain engine torque from a torque sensor that detects engine torque, or engine speed from an engine speed sensor that detects engine speed.

[0055] The target heat dissipation calculation unit 74 may calculate the target heat dissipation amount in a manner other than that described in the embodiment. For example, it may calculate the target heat dissipation amount according to the air conditioning set temperature, or it may calculate the target heat dissipation amount based on the air conditioning set temperature and the room temperature.

[0056] The engine heat dissipation calculation unit 75 may use something other than engine torque or engine speed as the operating state of the engine 31 for calculating the amount of heat dissipated by the engine 31. For example, the opening degree of the throttle valve for adjusting the intake amount of the engine 31 or the intake amount of the engine 31 may be used as the operating state of the engine 31.

[0057] The cooling medium may be water, oil, or something else.

[0058] 10...Vehicle (hybrid vehicle), 31...Engine, 43D...PTC heater (electric heater), 50...Control device, 70...Controller

Claims

1. A control method for a hybrid vehicle equipped with an engine and an electric heater for air conditioning, comprising: calculating a target heat dissipation amount which is a target value for the amount of heat dissipated by the engine and the electric heater; calculating the amount of heat dissipated by the engine based on the operating state of the engine; calculating a heat deficit amount relative to the target heat dissipation amount based on the target heat dissipation amount and the amount of heat dissipation by the engine; and controlling the electric heater based on the heat deficit amount.

2. A control method for a hybrid vehicle according to claim 1, wherein if the engine has not finished warming up, the power of the electric heater is limited to the lower limit value during warming up.

3. A control device for a hybrid vehicle equipped with an engine and an electric heater for air conditioning, comprising a controller for controlling the electric heater, wherein the controller calculates a target heat dissipation amount which is a target value for the amount of heat dissipated by the engine and the electric heater, calculates the amount of heat dissipated by the engine based on the operating state of the engine, calculates a heat deficit amount relative to the target heat dissipation amount based on the target heat dissipation amount and the amount of heat dissipated by the engine, and controls the electric heater based on the heat deficit amount.

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