JP6488549B2 - Hybrid vehicle and control method of hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle including an internal combustion engine and a motor generator, which can be assisted by the motor generator, and a hybrid vehicle control method.

  In a hybrid vehicle that includes an internal combustion engine and a motor generator and can be assisted by the motor generator, the engine runs alone using only the internal combustion engine as a power source, the motor runs independently using only the motor generator as a power source, and the internal combustion engine There are travel modes such as an assist travel that travels using both the motor and the motor generator as a power source, and a motor regenerative travel that generates electric power by the motor generator using the regenerative energy of the braking force of the hybrid vehicle.

  On the other hand, in an internal combustion engine, when the high-load operation continues, the temperature of the cooling water of the engine rises, exceeds the appropriate temperature necessary for the engine to function normally, and boils. Is insufficient and the engine body becomes overheated (overheated).

  In this overheated state, not only does the engine not operate normally, but the components that make up the engine are damaged by heat. In particular, in recent years, since an exhaust gas processing device is disposed in the exhaust passage of the engine, if the exhaust gas temperature becomes too high, the catalyst of this exhaust gas processing device will also deteriorate.

  In order to prevent overheating of the engine, the engine operating state is detected to determine the maximum fuel injection amount, and the maximum fuel injection amount is decreased and corrected based on the outside air temperature and the vehicle speed detected by the sensor. Thus, the amount of heat generated in the engine is reduced (see, for example, Patent Document 1).

  However, if the maximum injection amount of the internal combustion engine is limited in order to prevent overheating of the internal combustion engine, the vehicle decelerates unintentionally by the driver, so the driver steps on the accelerator to maintain the vehicle speed. And even if the accelerator is depressed, there is a problem that the driver feels uneasy if the vehicle speed continues to change.

  Also, by closing the EGR valve with EGR control, the temperature inside the cylinder can be lowered by lowering the temperature of the air-fuel mixture flowing into the cylinder, thereby reducing the engine output and the amount of heat generated by combustion. Overheating can be prevented. However, this method has a problem that NOx in the exhaust gas increases.

JP 2007-198171 A

  The present invention has been made in view of the above, and an object of the present invention is to provide a required driving force required for vehicle travel in a hybrid vehicle including an internal combustion engine and a motor generator that can be assisted by the motor generator. An object of the present invention is to provide a hybrid vehicle and a hybrid vehicle control method capable of avoiding an overheated state of the internal combustion engine without deteriorating the state of the exhaust gas discharged from the internal combustion engine while ensuring.

The hybrid vehicle of the present invention for achieving the above object, includes an internal combustion engine and an electric generator, in a hybrid vehicle capable assisted the electric generator, a control device that controls the hybrid vehicle, the internal combustion engine The time when the superheated state is entered is sequentially calculated, the calculated time is compared with a first period set in advance and a second period set shorter than the first period, and the time is within the first period. whether the timing includes an internal combustion engine overheat determination means for determining whether the second period, the timing the timing from the first time point was determined and the second period out in the first period During the first period and before a second time point determined to be within the second period, charge amount securing control is performed to secure a charge amount of a battery that is a power source of the motor generator, and the second time point and later, in the vehicle running Decreasing the rate of the driving force of the internal combustion engine for a main demand drive power, configured to shift to the overheat prevention control for assisting in generating the driving force in the electric generator.

  According to this configuration, the charge amount securing control is performed during the period from the first time point at which the internal combustion engine is determined to enter the first period to the second time point at which it is determined to enter the second period. The amount of power for assisting by the motor generator after the time point can be secured without being consumed or charged at any time. In addition, after the second time point, the amount of driving force generated by the internal combustion engine can be reduced by the amount of assistance from the motor generator, the load on the internal combustion engine can be reduced, and the amount of heat generated in the internal combustion engine can be reduced. The internal combustion engine can be prevented from being overheated (overheated).

  When the second period is set to zero, it becomes possible to determine when the internal combustion engine has entered an overheated state, and it is possible to employ a configuration in which assisting by a motor generator is performed after entering the overheated state. In other words, the above-described configuration includes a configuration in which the motor generator assists when the overheated state is entered.

  In the hybrid vehicle, the charge amount securing control is a discharge suppression control that suppresses discharge of a battery that is a power source of the motor generator, or a load amount generated in the internal combustion engine is greater than a preset load amount. When configured to include at least one of light load charge control for charging the battery by performing power generation by the motor generator at the time of a small light load operation, the assist of the motor generator such as accompanying battery discharge, Discharge suppression control that stops the motor alone and the use of power equipment that uses a battery as a power source, or when the internal combustion engine has a margin to generate power by the motor generator at light load operation, The charge amount of the battery can be easily ensured in at least one of the light load charge control in which the battery is charged.

  In the above hybrid vehicle, the internal combustion engine overheat determination means may be configured to overheat the internal combustion engine within the first period or the second period based on time-series data of the coolant temperature of the internal combustion engine. If it is configured to determine whether or not to enter the state, the time-series rising tendency of the cooling water temperature, which is the temperature of the cooling water for cooling the internal combustion engine, and the cooling water temperature at the time of determination remain unchanged. When the operating state of the internal combustion engine is continued, it is possible to easily calculate the timing (timing) at which the coolant temperature exceeds the overheat determination temperature. Therefore, the first and second periods (timing) in which the exceeding timing is set in advance are determined. ), It is possible to easily determine whether or not the internal combustion engine enters an overheat state within the first period or the second period.

  In the above hybrid vehicle, the internal combustion engine overheat determination means includes the air temperature data in addition to the time series data of the cooling water temperature of the internal combustion engine, and the second period or the second time period. If it is configured to determine whether the internal combustion engine enters an overheated state within a period, the cooling amount of the internal combustion engine varies depending on the atmospheric temperature, so the predicted value of the cooling water temperature is affected by the atmospheric temperature. Therefore, the time when the internal combustion engine enters the overheated state can be estimated more accurately by taking this atmospheric temperature data into consideration.

And the hybrid vehicle control method of the present invention for achieving the above object comprises an internal combustion engine and a motor generator, wherein the internal combustion engine is in an overheated state in the hybrid vehicle control method that can be assisted by the motor generator. The time to enter is sequentially calculated, and the calculated time is compared with the first period set in advance and the second period set to a period shorter than the first period, so that the time is within the first period. Determining whether the time is within the second period, and from the first time point when the time is determined to be within the first period and out of the second period, the time is within the first period and Until the second time point determined to be within the second period, charge amount securing control for securing the charge amount of the battery serving as the power source of the motor generator is performed, and after the second time point , necessary for vehicle travel The internal combustion engine for the required driving force. Decreasing the rate of power, it generates a driving force by the motor generator is a method characterized by moving to overheat avoidance control to assist. According to this method, the same effect as the above hybrid vehicle can be obtained.

  According to the hybrid vehicle and the hybrid vehicle control method of the present invention, in a hybrid vehicle that includes an internal combustion engine and a motor generator and can be assisted by the motor generator, predicting and determining when the internal combustion engine enters an overheat state is performed. Since sufficient power is stored in the battery by performing charge amount securing control before entering the state, after shifting to overheat avoidance control assisted by the motor generator, motor power generation is performed with sufficient power stored in the battery. This assist can reduce the load on the internal combustion engine and reduce the amount of heat generated in the internal combustion engine. Therefore, the internal combustion engine can be prevented from being overheated without deteriorating the state of the exhaust gas discharged from the internal combustion engine while ensuring the necessary driving force required for vehicle travel.

It is the figure which showed typically the structure of the hybrid vehicle of embodiment which concerns on this invention, and is a figure which shows the assist state by a motor generator. It is a figure which shows an example of the control flow of the control method of the hybrid vehicle of embodiment which concerns on this invention.

  Hereinafter, a hybrid vehicle and a hybrid vehicle control method according to embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, a hybrid vehicle (HEV) 1 of this embodiment includes an engine (internal combustion engine) 10, a motor generator (running motor / generator) 20, and a transmission 30. The vehicle is a vehicle that transmits the power of the motor generator 20 to the wheels 34 via the transmission 30, and the vehicle can use both the engine 10 and the motor generator 20 as a power source for traveling.

  Here, the parallel hybrid vehicle shown in FIG. 1 will be described as an example. However, the parallel hybrid vehicle is not necessarily required, and the driving force generated by the internal combustion engine 10 is assisted (assisted) by the motor generator 20. Any hybrid vehicle having such a function can be used.

  As shown in FIG. 1, the power of the engine 10 is supplied from a torque converter 13 connected to the engine 10, a connected engine running clutch 14, a transmission 30 and a propeller shaft 31 to a differential device (differential gear) 32. And further transmitted to the wheel 34 via the axle 33.

  On the other hand, the motive power of the motor generator 20 is generated when the electric power charged (accumulated) in the battery 22 is supplied to the motor generator 20 via the inverter 21, and this motive power is generated by the connected motor running clutch. 23, the transmission 30, and the propeller shaft 31 are transmitted to the differential device 32, and further transmitted to the wheels 34 via the axle 33.

  Accordingly, one or both of the power of the engine 10 and the power of the motor generator 20 are transmitted to the wheels 34 via the transmission 30, and the hybrid vehicle 1 travels.

  In the configuration of FIG. 1, transmission and disconnection of the power of the engine 10 to the wheels 34 are performed by switching the connection and disconnection of the engine travel clutch 14, and by switching and connection of the motor travel clutch 23, The power of the motor generator 20 is transmitted to and cut off from the wheels 34, but it is sufficient that the power of the engine 10 or the power of the motor generator 20 can be properly switched between transmission and interruption. The travel clutch 23 may not be provided.

  Further, in order to purify NOx (nitrogen oxide), PM (particulate matter), etc. in the exhaust gas G of the engine 10, exhaust gas purification provided with a NOx reduction catalyst device 12a, a PM collection filter device 12b, etc. A device 12 is disposed in the exhaust passage 11 to purify NOx, PM, etc. in the exhaust gas G.

  A hybrid system 2 including the engine 10, the motor generator 20, and the transmission 30, and a control device 40 for controlling the hybrid vehicle 1 are provided. The control device 40 controls the engine 10 in general. The overall control of the hybrid vehicle 1 including the overall control of the motor generator 20 by the inverter 21, the overall control of the hybrid system 2 including the connection / disconnection control of the engine travel clutch 14 and the connection / disconnection control of the motor travel clutch 23. And so on.

  The control device 40 that controls the hybrid vehicle 1 on which the hybrid system 2 is mounted includes an internal combustion engine overheat determination unit 41 that determines whether or not the engine 10 enters an overheat state.

The internal combustion engine overheat determination means 41 determines whether or not the engine 10 enters an overheat state within a preset first period t1, and the engine 10 enters an overheat state within a preset second period t2. It is determined whether or not. The second period t2 is set to be shorter than the first period t1, for example, the first period t1 is set to about 60 seconds to 120 seconds , and the second period t2 is set to about 30 seconds to 60 seconds .

  When the internal combustion engine overheat determination unit 41 determines that the engine 10 enters an overheated state within the first period t1, the control device 40 suppresses the discharge of the battery 22 serving as the power source of the motor generator 20. Discharge suppression control to be performed, or charge control at light load in which the motor 22 generates power and charges the battery 22 during light load operation in which the load amount Qea generated in the engine 10 is smaller than the preset load amount Qec The charge amount securing control for securing the charge amount of the battery 22 serving as the power source of the motor generator 20 is performed, and the internal combustion engine overheat determination means 41 causes the engine 10 to overheat within the second period t2. If it is determined that the vehicle is to enter the state, the motor generator 20 generates a driving force Qm to assist, and at the same time, drives the engine 10 with respect to the required driving force Qt required for vehicle travel. Configured to transition to the overheat prevention control for reducing the rate of force Qe Ret (= Qe / Qt).

  The internal combustion engine overheat determination means 41 determines whether or not the engine 10 enters an overheated state within the first period t1 or the second period t2 based on time-series data of the coolant temperature Tw of the engine 10. Determine.

That is, when the cooling water temperature Tw, which is the temperature of the cooling water that cools the engine 10, rises in time series, for example, when the elapsed time is t and the increment of the cooling water temperature Tw within a certain time increment Δt is ΔTw, Using the immediately preceding time series data Tw ₋₁ , ΔTw = Tw−Tw _{−1 is obtained} , and the engine 10 is operated as it is based on the differential value dTw / dt (= ΔTw / Δt) and the coolant temperature Tw at the time of determination. When the state continues, the timing (timing) tx at which the cooling water temperature Tw exceeds the overheat determination temperature Twc can be easily calculated. Since Twc = Tw + tx × ΔTw / Δt, tx = (Twc−Tw) / (ΔTw / Δt).

  Whether or not the engine 10 enters an overheated state within the first period t1 or the second period t2 is easily compared by comparing the time tx that exceeds this time with the first period t1 and the second period t2 set in advance. Can be determined.

  In addition, not only the cooling water temperature Tw and the differential value dTw / dt at the time of determination, but also a curve showing the transition of the cooling water temperature Tw using the previous time series data is obtained by regression analysis or the like, and from this curve The timing (timing) tx at which the cooling water temperature Tw exceeds the overheat determination temperature Twc can also be calculated. In this case, it is possible to predict more accurately and control with higher accuracy is possible. This overheat determination temperature Twc is set to a temperature between 90 ° C. and 100 ° C., for example.

  Further, the internal combustion engine overheat determination means 41 takes into account the data of the atmospheric temperature Ta in addition to the time-series data Tw of the coolant temperature Tw of the engine 10, and within the first period t1 or the second period t2. Preferably, the engine 10 is configured to determine whether the engine 10 enters an overheated state. As a result, the amount of cooling of the engine 10 varies depending on the atmospheric temperature Ta, so the predicted value of the cooling water temperature Tw is affected by the atmospheric temperature Ta. It becomes possible to estimate the time tx when 10 enters the overheated state. That is, if the atmospheric temperature Ta is high, the cooling effect is reduced and overheating is likely to occur, so the first period t1 and the second period t2 are lengthened. On the other hand, if the atmospheric temperature Ta is low, the cooling effect increases and it is difficult to overheat, so the first period t1 and the second period t2 are shortened.

  Then, the charge amount securing control in which at least one of the discharge suppression control and the light load charge control is performed is determined within the second period t2 from the first time point ta when it is determined that the engine 10 enters the overheated state within the first period t1. It is performed until the second time point tb determined to enter.

  In this discharge suppression control, the motor travel clutch 23 is disengaged, the assist of the motor generator 20 and the motor independent travel, which accompanies the discharge of the battery 22, are stopped, and the battery 22 is connected to the power source. Stop using other power devices, such as air conditioners. Thereby, it is possible to secure the amount of power for assisting by the motor generator 20 after the second time point tb without consuming it.

  On the other hand, in the light load charge control, even if a part of the output of the engine 10 is used to generate power with the motor generator 20, the motor generator 20 generates power when the engine 10 has a light load operation with a margin. The battery 22 is charged. Whether or not the operation is light load is determined by whether or not the load amount Qea generated in the engine 10 is smaller than a preset load amount Qec.

  The overheat avoidance control is performed after the second time point tb, assists the motor generator 20 by generating the driving force Qm with the motor traveling clutch 23 in the connected state, and the required driving force required for vehicle traveling. The ratio Ret (= Qe / Qt) of the driving force Qe of the engine 10 with respect to Qt is decreased. As a result, the generation amount of the driving force Qe of the engine 10 can be reduced by the amount of assistance from the motor generator 20, the load on the engine 10 can be reduced, and the generated heat amount in the engine 10 can be reduced. It can avoid becoming a state.

  When the second period t2 is set to zero, it becomes possible to determine the time point tc (= tb) when the engine 10 has entered an overheated state, and has entered an overheated state, not from the time point tb before entering the overheated state. From time to time, the motor generator 20 can assist.

  Next, a hybrid vehicle control method according to an embodiment of the present invention will be described with reference to the control flow of FIG. The control flow of FIG. 2 is called from the advanced control flow when the operation of the hybrid vehicle 1 is started, and is performed in parallel with the control of the operation of the normal hybrid vehicle 1. When stopped, it is shown as a control flow that returns to an advanced control flow by interruption and ends with an advanced control flow.

  When the control flow of FIG. 2 is started, it is determined in step S11 whether or not the engine 10 enters an overheat state within a preset first period t1. If it is determined in this determination that the engine 10 does not enter an overheated state within the first period t1 (NO), the normal hybrid vehicle 1 is controlled by another control flow, and after a preset control time Δti has elapsed. Return to step S11.

  On the other hand, if it is determined in step S11 that the engine 10 enters an overheated state within the first period t1 (YES), the process goes to step S12. In step S12, it is determined whether or not the engine 10 enters an overheated state within a preset second period t2.

  If it is determined in step S12 that the engine 10 does not enter an overheated state within the second period t2 (NO), the process goes to step S13 to secure the charge amount of the battery 22 serving as the power source of the motor generator 20. The charge amount securing control is performed with priority over the control of the normal hybrid vehicle 1, and after a preset control time Δti has elapsed, the process returns to step S11. In this charge amount securing control, discharge suppression control for suppressing discharge of the battery 22 serving as the power source of the motor generator 20, or light load operation in which the load amount Qea generated in the engine 10 is smaller than the preset load amount Qec. At this time, at least one of the light load charging control for generating the electric power by the motor generator 20 and charging the battery 22 is performed.

  On the other hand, if it is determined in step S12 that the engine 10 enters an overheated state within the second period t2 (YES), the process goes to step S14, where the motor generator 20 generates a driving force Qm to assist and After overheating avoidance control for reducing the ratio Ret of the driving force Qe of the engine 10 to the required driving force Qt necessary for traveling is given priority over the control of the normal hybrid vehicle 1, and after a preset control time Δti has elapsed. Return to step S11.

  Then, Step S11 to Step S13 or Step S14 are repeatedly performed, and when the operation of the hybrid vehicle 1 is stopped, the interruption is returned to return to the advanced control flow, and with the end of the advanced control flow, The control flow in FIG. 2 is also terminated.

  In addition, according to the control according to the control flow of FIG. 2, it is determined whether or not the engine 10 enters the overheat state, and it is determined that the engine 10 enters the overheat state within the preset first period t1. The charge amount securing control for securing the charge amount of the battery 22 serving as the power source of the motor generator 20 is performed, and the engine 10 enters an overheated state within a preset second period t2, which is shorter than the first period t1. If it is determined, the motor generator 20 generates the driving force Qe to assist and shifts to the overheat avoidance control that reduces the ratio Ret of the driving force Qe of the engine 10 to the required driving force Qt required for vehicle travel. can do.

  Therefore, according to the hybrid vehicle 1 and the hybrid vehicle control method described above, in the hybrid vehicle 1 that includes the engine 10 and the motor generator 20 and can be assisted by the motor generator 20, it is predicted when the engine 10 enters an overheated state. Therefore, the battery 22 is stored in the battery 22 after the transition to the overheat avoidance control assisted by the motor generator 20 because the charge amount securing control is performed and the battery 22 is stored with sufficient power before the overheat state is determined. The motor generator 20 can assist with a sufficient amount of electric power. With this assist, the load on the engine 10 can be reduced and the amount of heat generated in the engine 10 can be reduced. Therefore, it is possible to avoid overheating of the engine 10 without deteriorating the state of the exhaust gas G exhausted from the engine 10 while ensuring the necessary driving force Qt required for vehicle travel.

1 Hybrid vehicle (HEV)
2 Hybrid system 10 engine (internal combustion engine)
11 Exhaust passage 12 Exhaust gas purification device 12a NOx reduction catalyst device 12b PM collection filter device 13 Torque converter 14 Engine travel clutch 20 Motor generator (motor / generator for travel)
21 Inverter 22 Battery 23 Motor running clutch 30 Transmission 31 Propeller shaft 32 Differential (differential gear)
33 Axle 34 Wheel 40 Controller 41 Internal combustion engine overheat determination means G Exhaust gas Qe Engine driving force Qea Engine load amount Qec Preset load amount Qm Motor generator driving force Qt Required driving force Ret required for vehicle travel Ratio t of engine driving force with respect to driving force Elapsed time t1 First period t2 Second period ta First time point tb Second time point tc Time point when the engine enters an overheat state tx Time when the coolant temperature exceeds the overheat determination temperature Ta Atmospheric temperature Tw Cooling water temperature Tw _-1 Time series data Twc immediately before cooling water temperature Overheating determination temperature Δt Time increment Δti Control time ΔTw Increment of cooling water temperature

Claims (5)

In a hybrid vehicle comprising an internal combustion engine and a motor generator, which can be assisted by the motor generator,
A control device for controlling the hybrid vehicle includes:
The time when the internal combustion engine enters an overheated state is sequentially calculated, and the calculated time is compared with a first period set in advance and a second period set shorter than the first period. whether in one period, it includes an internal combustion engine overheat determination means the timing to determine whether the second time period,
Between the first time point when the time is determined to be within the first period and outside the second time period to the second time point when the time is determined to be within the first time period and within the second time period, Perform charge amount securing control to secure the charge amount of the battery that is the power source of the generator,
After the second time point, the ratio of the driving force of the internal combustion engine to the required driving force required for vehicle travel is reduced, and the process shifts to overheat avoidance control in which the motor generator generates driving force and assists. A hybrid vehicle characterized by being made.   When the charge amount securing control is a discharge suppression control that suppresses discharge of a battery that is a power source of the motor generator, or a light load operation in which a load amount generated in the internal combustion engine is smaller than a preset load amount The hybrid vehicle according to claim 1, further comprising at least one of light load charge control for charging the battery by generating power by the motor generator. The internal combustion engine overheat determination means determines whether the timing is within the first period and whether the timing is within the second period based on time-series data of the coolant temperature of the internal combustion engine. The hybrid vehicle according to claim 1, wherein the hybrid vehicle is configured as described above. The internal combustion engine overheat determination means takes into account the air temperature data in addition to the time series data of the cooling water temperature of the internal combustion engine, and whether the time is within the first period or not. The hybrid vehicle according to claim 3, wherein the hybrid vehicle is configured to determine whether or not it is within two periods . In a control method of a hybrid vehicle comprising an internal combustion engine and a motor generator, which can be assisted by the motor generator,
Sequentially calculating when the internal combustion engine enters an overheated state ,
The calculated period is compared with a first period set in advance and a second period set to a period shorter than the first period, and whether or not the period is within the first period is determined. Determine whether it is within 2 periods,
Between the first time point when the time is determined to be within the first period and outside the second time period to the second time point when the time is determined to be within the first time period and within the second time period, Perform charge amount securing control to secure the charge amount of the battery that is the power source of the generator,
After the second time point, the ratio of the driving force of the internal combustion engine to the required driving force required for vehicle travel is decreased, and the process shifts to overheat avoidance control in which the motor generator generates driving force and assists. A control method for a hybrid vehicle.

Images