Hybrid vehicle and method for controlling hybrid vehicle

Abstract

To provide a hybrid vehicle that can prevent occurrence of a surge and maintain mobility while suppressing increase in computational amount.SOLUTION: The hybrid vehicle includes: a first determination unit that determines a surge state of a turbocharger based on a state of an engine; a second determination unit that determines the surge state of the turbocharger based on the state of the turbocharger; and a control unit that controls the engine and assist of the engine by an electric driving motor based on determination results obtained by the first determination unit and the second determination unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a hybrid vehicle and a control method for a hybrid vehicle. [Background technology]

[0002] Conventionally, there is a hybrid vehicle equipped with an engine, a turbocharger, and an electric drive motor, as described in, for example, Patent Document 1. Patent Document 1 describes a technology that controls the engine so as to avoid the surging phenomenon that occurs in the compressor of the turbocharger, and compensates for the reduction in driving force of the engine at this time with the driving force of the electric drive motor. The technology of Patent Document 1 makes it possible to realize a hybrid vehicle that can avoid the surging phenomenon of the turbocharger while maintaining drivability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-182725 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the hybrid vehicle described in Patent Document 1, the occurrence of surging (hereinafter also referred to as surge) is predicted based on the engine rotation speed, the upshift of the transmission, and the vehicle speed, and the engine and the electric drive motor are controlled.

[0005] Therefore, in the hybrid vehicle described in Patent Document 1, if it is applied to a vehicle with a continuously variable transmission, etc., it may be impossible to predict a surge. Also, in the hybrid vehicle described in Patent Document 1, a surge may occur when the accelerator is suddenly released.

[0006] Moreover, in the conventional configuration, it is considered that in order to reliably prevent surges, the amount of calculations would increase and the control would become complicated.

[0007] The present disclosure has been made in consideration of the above points, and provides a hybrid vehicle and a control method for a hybrid vehicle that can prevent the occurrence of a surge and maintain mobility while suppressing an increase in the amount of calculations. [Means for solving the problem]

[0008] One aspect of the hybrid vehicle of the present disclosure is to The engine, a turbocharger connected to an intake and exhaust system of the engine; An electric drive motor; a first determination unit that determines a surge state of the turbocharger based on a state of the engine; A second determination unit that determines a surge state of the turbocharger based on a state of the turbocharger; a control unit that controls the engine and the assist of the engine by the electric drive motor based on determination results of the first determination unit and the second determination unit; Equipped with.

[0009] One aspect of the control method for a hybrid vehicle of the present disclosure includes: A method for controlling a hybrid vehicle having an engine, a turbocharger connected to an intake and exhaust system of the engine, and an electric drive motor, comprising the steps of: a first determination step of determining a surge state of the turbocharger based on a state of the engine; a second determination step of determining a surge state of the turbocharger based on a state of the turbocharger; a control step of controlling the engine and the assist of the engine by the electric drive motor based on the determination results of the first determination step and the second determination step; Includes. Effect of the Invention

[0010] According to the present disclosure, it is possible to realize a hybrid vehicle and a control method for a hybrid vehicle that can prevent the occurrence of a surge and maintain mobility while suppressing an increase in the amount of calculations. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a main configuration of a hybrid vehicle according to an embodiment; [Diagram 2] 1 is a flowchart for explaining the operation of an embodiment. [Diagram 3] FIG. 10 is a diagram for explaining the determination process of the first determination unit, showing the relationship between the engine speed, the fuel flow rate, and a state corresponding to the vicinity of the surge region; [Figure 4] FIG. 10 is a diagram for explaining the judgment process of the first judgment unit, showing the relationship between the corrected air flow rate, the pressure ratio of the compressor inlet and outlet pressures, and the region corresponding to the vicinity of the surge region. [Diagram 5] FIG. 1 is a diagram for explaining a difference between a vehicle required torque and an actual engine torque. [Figure 6] A diagram showing an example of motor rotation speed and output torque of an electric drive motor DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] 1 is a schematic diagram showing the main configuration of a hybrid vehicle 1 according to an embodiment. The hybrid vehicle 1 has an internal combustion engine (such as a diesel engine or a gasoline engine; hereinafter, referred to as the engine) 10, a turbocharger 20 connected to an intake and exhaust system of the engine 10, a power transmission mechanism 30 that transmits the driving torque generated by the engine 10, an electric drive motor 40 connected to the power transmission mechanism 30, and a battery 42 electrically connected to the electric drive motor 40 via an inverter 41.

[0014] The engine 10 has an engine body 11, an exhaust manifold 12, an intake manifold 13, etc. Exhaust gas generated in the engine body 11 is sent to a turbocharger 20 via the exhaust manifold 12, drives a turbine 21 of the turbocharger 20, and is purified in an exhaust gas treatment device 51 before being discharged.

[0015] In addition, the intake air drawn into the engine body 11 through the air cleaner 52 is compressed and cooled by the compressor 22 and intake cooler 53 of the turbocharger 20, and is adjusted by the intake throttle 54 before being supplied to the engine body 11 via the intake manifold 13.

[0016] The power transmission mechanism 30 transmits the driving torque generated by the engine 10 to a transmission (gearbox) 33 via a torque converter 31 and a friction clutch (e.g., a wet clutch using a viscous coupling) 32. The driving torque is then transmitted from the transmission 33 to driving wheels 55 via a propeller shaft 34, a differential 35, and a drive shaft 36. Note that the configuration of the power transmission mechanism is not limited to this. The power transmission mechanism may be, for example, a CVT (Continuously Variable Transmission) or a DCT (Dual Clutch Transmission).

[0017] Further, the driving torque generated by the electric drive motor 40 is transmitted to the driving wheels 55 via a slave dog clutch (hereinafter referred to as dog clutch) 37a of the PTO (power input / output mechanism) 37. Note that the present disclosure is not limited to hybrid vehicles of the type in which the driving torque generated by the electric drive motor 40 is transmitted to the driving wheels 55 via the PTO 37, but is broadly applicable to known hybrid vehicles in which the electric drive motor 40 performs driving assist and regeneration.

[0018] When the electric drive motor 40 is driven in a regenerative manner, it acts as a generator to apply a braking force to the power transmission mechanism 30 to generate regenerative electricity, and when it is driven in a power running manner, it acts as an electric motor to apply a driving force to the power transmission mechanism 30 to assist it. The electric power obtained by the power generation is converted by the inverter 41 and charged in the battery 42. When the electric drive motor 40 is driven electrically, the electric power charged in the battery 42 is converted by the inverter 41 and supplied to the electric drive motor 40.

[0019] Furthermore, the hybrid vehicle 1 has a control unit 60. The control unit 60 has a control unit 61, a first determination unit 62, and a second determination unit 63. Each of the control unit 61, the first determination unit 62, and the second determination unit 63 has a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), etc. as main components. The CPU reads out a program corresponding to the processing content from the ROM and loads it in the RAM, and realizes each function of the control unit 61, the first determination unit 62, and the second determination unit 63 in cooperation with the loaded program. Note that all or part of the control unit 61, the first determination unit 62, and the second determination unit 63 may be formed by a hardwired circuit such as an application specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0020] The first determination unit 62 receives the engine speed from the engine speed sensor 71, the fuel flow rate from the fuel sensor 72, and the accelerator opening from the accelerator sensor 73. The first determination unit 52 determines the surge state of the turbocharger 20 based on the engine speed and the fuel flow rate or the accelerator opening.

[0021] In this specification, the term "surge state" is not limited to a state in which a surge occurs, but includes a state close to a state in which a surge occurs and a state leading to a surge. In other words, the term "surge state" may be read as a "state close to a surge" or a "state related to a surge."

[0022] The second determination unit 63 receives as input pressure values ​​from pressure sensors 74a, 74b provided at the inlet and outlet of the compressor 22 of the turbocharger 20, a turbine rotation speed from a turbine rotation sensor 75, and a compressor intake air amount from a flow rate sensor (MAF (Mass Flow) sensor) 76. The second determination unit 63 determines a surge state of the turbocharger based on the pressure difference (or pressure ratio) between the outlet and inlet of the compressor 22 of the turbocharger 20, the rotation speed of the turbine 21, and the intake air amount of the compressor 22.

[0023] The control unit 61 controls the engine 10 and the assist of the engine 10 by the electric drive motor 40 based on the determination results of the first determination unit 62 and the second determination unit 63. Specifically, when the first determination unit 62 and the second determination unit 63 obtain a determination result that the turbocharger 20 is close to a surge state, the control unit 61 performs control to suppress the rotation speed and fuel flow rate of the engine 10 and to assist the engine 10 by the electric drive motor 40. Note that, although not shown, actually, vehicle state information such as vehicle speed, vehicle weight, gear position, etc. is also input to the control unit 61, and the control unit 61 performs control to suppress the rotation speed and fuel flow rate of the engine 10 by taking into account the determination results of the first determination unit 62 and the second determination unit 63 as well as the vehicle state information.

[0024] FIG. 2 is a flowchart illustrating the operation of hybrid vehicle 1 according to the present embodiment.

[0025] In step S11, the hybrid vehicle 1 waits for the ignition switch to be turned on, and when the ignition switch is turned on (step S11; YES), the process proceeds to step S12.

[0026] In step S12, the first determination unit 62 reads the engine speed (Ne), the fuel flow rate (Q), and the accelerator opening (APS). In the following step S13, the first determination unit 62 determines whether the operating state of the engine 10 corresponds to a state near the surge region of the turbocharger 20. Specifically, when the relationship between the engine speed and the fuel flow rate (or the accelerator opening (which may also be called engine torque)) (i.e., the operating point of the engine 10) is in the shaded region A in Fig. 3, the first determination unit 62 determines that the operating state of the engine 10 corresponds to a state near the surge region of the turbocharger 20 (step S13; YES), and proceeds to step S14.

[0027] In step S14, the second determination unit 63 reads the compressor inlet and outlet pressures, the turbo rotation speed, and the intake air amount (MAF value). In the following step S15, the second determination unit 63 determines whether the operating state of the compressor 22 of the turbocharger 20 is near the surge region. Specifically, the second determination unit 63 calculates a corrected air flow rate from the turbine rotation speed of the compressor 22 and the intake air amount of the compressor 22, and if the relationship between this corrected air flow rate and the pressure ratio of the compressor inlet and outlet pressures (i.e., the operating point of the compressor 22) is in the region B shown by the hatched pattern in Fig. 4, it is determined that the operating state of the compressor 22 is near the surge region (step S15; YES), and the process proceeds to step S16.

[0028] In addition, the judgment in step S15 uses a compressor map such as that shown in Figure 4. However, since this compressor map depends on temperature, it is preferable to prepare multiple compressor maps according to temperatures and make the judgment in step S15 using the compressor map according to the intake temperature of compressor 22.

[0029] In step S16, the control unit 61 monitors vehicle conditions such as vehicle speed, vehicle weight, gear position, etc. In step S17, the control unit 61 controls the engine 10 to maintain the engine rotation speed and fuel flow rate (engine side operation control). That is, the control unit 61 suppresses the rotation speed and fuel flow rate of the engine 10.

[0030] In step S18, the control unit 61 calculates the difference between the vehicle required torque and the actual engine torque. The vehicle required torque is the torque required for vehicle performance, calculated by taking into account the accelerator opening as well as the vehicle weight and the like. The actual engine torque is the engine torque after the rotation speed and fuel flow rate of the engine 10 are suppressed in step S16 so as not to cause a surge. The control unit 61 calculates the difference between the vehicle required torque and the actual engine torque, which is caused by suppressing the rotation speed and fuel flow rate of the engine 10 in step S16 so as not to cause a surge. FIG. 5 shows this process.

[0031] In the next step S19, the control unit 61 controls the electric drive motor 40 to assist the engine 10. Specifically, the control unit 61 controls the electric drive motor 40 so that a torque equivalent to the difference calculated in step S18 is output, thereby compensating for the reduction in engine torque suppressed to avoid a surge with the output torque of the electric drive motor 40. Note that Fig. 6 shows an example of the motor rotation speed and output torque of the electric drive motor 40.

[0032] If hybrid vehicle 1 determines in subsequent step S20 that the ignition switch is OFF (step S20; YES), it ends the process, and if it determines that the ignition switch is not OFF (step S20; NO), it returns to step S12 and repeats the above-mentioned process.

[0033] As described above, according to this embodiment, the hybrid vehicle 1 is equipped with a first judgment unit 62 that judges a surge state of the turbocharger 20 based on the state of the engine 10, a second judgment unit 63 that judges a surge state of the turbocharger 20 based on the state of the turbocharger 20, and a control unit 61 that controls the engine 10 and the assistance of the engine 10 by the electric drive motor 40 based on the judgment results of the first judgment unit 62 and the second judgment unit 63.

[0034] This makes it possible to realize a hybrid vehicle 1 that can prevent surges while suppressing an increase in the amount of calculations and maintains maneuverability.

[0035] Here, in the embodiment, first determination unit 62 performs a process of determining a surge state using parameters of engine 10, and when the first determination unit 62 obtains a determination result that the state is close to a surge state, second determination unit 63 performs a process of determining a surge state using parameters of turbocharger 20. In other words, it can be said that the first determination unit 62 narrows down the surge state based on a rough determination, and then the second determination unit 63 performs a detailed determination of the surge state.

[0036] The judgment by the second judgment unit 63 includes a process of calculating a corrected air flow rate from the turbine rotation speed of the compressor 22 and the intake air amount of the compressor 22, so if all operating points of the compressor map as shown in Fig. 4 were to be processed, the amount of calculations would become very large. In contrast, the judgment by the first judgment unit 62 can be easily performed from the relationship between the engine rotation speed and the fuel flow rate (or the accelerator opening), so it can be realized with a small amount of calculations.

[0037] In this embodiment, taking this into consideration, the first judgment unit 62 first roughly judges whether the state is near a surge state, and then, if the first judgment unit 62 judges that the state is near a surge state, the second judgment unit 63 judges in detail whether the state is near a surge state. In particular, as can be seen from Fig. 4, on the low-speed, high-load side, the differential point is close to the surge line, so that precise control in that region is required. In this embodiment, the first judgment unit 62 narrows down the region in which the second judgment unit 63 performs judgment processing to the vicinity of the surge line, and the second judgment unit 63 can perform precise judgment near the surge line.

[0038] This makes it possible to reliably determine whether or not a surge is occurring with a small amount of calculation. When the second determination unit 63 determines that a surge is occurring, the control unit 61 controls the electric drive motor 40 to compensate for the reduction in engine torque while suppressing engine drive. As a result, it is possible to realize a hybrid vehicle 1 that can prevent the occurrence of a surge and maintain maneuverability while suppressing an increase in the amount of calculation.

[0039] The above-described embodiments are merely examples of the implementation of the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these embodiments. In other words, the present disclosure can be implemented in various forms without departing from the gist or main characteristics of the disclosure. [Industrial Applicability]

[0040] The present disclosure may be applied to a hybrid vehicle that includes an engine, a turbocharger, and an electric drive motor. [Explanation of symbols]

[0041] 1 Hybrid vehicles 10 Engine 20 Turbocharger 21 Turbine 22 Compressor 30 Power transmission mechanism 40 Electric drive motor 60 Control unit 60 61 Control section 62 1st judgment part 63 Second Judgment Section 71 Engine revolution sensor 72 Fuel sensor 73 Accelerator Sensor 74a, 74b Pressure sensor 75 Turbine rotation sensor 76 Flow Sensor

Claims

1. The engine, a turbocharger connected to an intake and exhaust system of the engine; An electric drive motor; a first determination unit that determines a surge state of the turbocharger based on a state of the engine; a second determination unit that determines a surge state of the turbocharger based on a state of the turbocharger; a control unit that controls the engine and the assist of the engine by the electric drive motor based on determination results of the first determination unit and the second determination unit; A hybrid vehicle equipped with

2. The first determination unit determines a surge state of the turbocharger based on an engine rotation speed, and a fuel flow rate or an accelerator opening degree. The hybrid vehicle according to claim 1 .

3. the second determination unit determines a surge state of the turbocharger based on pressures at an outlet and an inlet of a compressor of the turbocharger, a turbine rotation speed, and an intake air amount of the compressor; The hybrid vehicle according to claim 1 .

4. The control unit is when the first determination unit and the second determination unit obtain a determination result that the turbocharger is close to a surge state, a rotation speed and a fuel flow rate of the engine are suppressed, and the engine is assisted by the electric drive motor. The hybrid vehicle according to claim 1 .

5. The control unit is calculating a difference between a required torque and an engine torque after suppressing the rotation speed of the engine and the fuel flow rate, and controlling the electric drive motor to output a torque corresponding to the difference; The hybrid vehicle according to claim 4.

6. the determination by the second determination unit is made when the determination result obtained by the first determination unit indicates that the turbocharger is close to a surge state; The hybrid vehicle according to claim 1 .

7. A method for controlling a hybrid vehicle having an engine, a turbocharger connected to an intake and exhaust system of the engine, and an electric drive motor, comprising the steps of: a first determination step of determining a surge state of the turbocharger based on a state of the engine; a second determination step of determining a surge state of the turbocharger based on a state of the turbocharger; a control step of controlling the engine and the assist of the engine by the electric drive motor based on the determination results of the first determination step and the second determination step; A method for controlling a hybrid vehicle, comprising:

8. the second determination step is performed when a determination result that the turbocharger is in a vicinity of a surge state is obtained in the first determination step. The method for controlling a hybrid vehicle according to claim 7.

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