Hybrid vehicles

Abstract

To provide a control device of a hybrid vehicle, which prevents overcharging of a battery and can secure an opportunity to examine a state of an engine.SOLUTION: A hybrid vehicle comprising a motor as a driving source for traveling, a battery for supplying power to the motor, and an engine is provided with: a determination part for determining whether or not a prescribed switching operation of switching a driving mode of the vehicle from a normal mode for performing normal traveling to a special mode for examining a state of the engine is performed; and an engine control part for controlling the engine. If the determination part determines that the switching operation is performed, the engine control part makes engine to start combustion of air fuel mixture and makes the engine torque produced by the combustion be equal to or lower than the minimum value of the engine torque produced during the normal mode.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to hybrid vehicles. [Background technology]

[0002] So-called hybrid vehicles that have a motor in addition to an engine as a drive source are known. For example, Patent Document 1 discloses a hybrid vehicle in which the engine and the motor are connected to the wheels and both operate as drive sources for traveling.

[0003] In hybrid vehicles, as in vehicles that have only an engine as a drive source, the engine condition must be checked as needed. For example, after replacing engine parts, it is necessary to check whether the engine is operating properly. Engine performance must also be inspected. In contrast, the vehicle disclosed in Patent Document 1 is configured so that the engine is driven by inputting a predetermined signal to a controller that controls the engine, regardless of whether a vehicle-specific engine stop condition is met. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2982746 Summary of the Invention [Problem to be solved by the invention]

[0005] Some hybrid vehicles are equipped with a generator driven by an engine and a battery that stores electricity supplied by the generator. In such vehicles, when the engine rotates, the generator generates electricity, increasing the power supplied to the battery. Therefore, if the engine is simply driven when checking the engine status, the battery may be overcharged due to the continued supply of power. However, battery overcharging can be prevented by configuring the engine to stop when the battery is fully charged. However, simply stopping the engine when the battery is fully charged does not provide sufficient opportunities to run the engine, i.e., to check the engine status.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a control device for a hybrid vehicle that can prevent overcharging of the battery and ensure an opportunity to check the state of the engine. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a vehicle comprising a motor as a driving source for traveling, a battery for supplying power to the motor, an engine having a combustion chamber in which an air-fuel mixture is burned, and a generator driven by the engine. and charge the battery A generator that an accelerator pedal operated by a driver; a determination unit that determines whether a predetermined switching operation has been performed to switch a vehicle's driving mode from a normal mode for normal driving to a special mode for checking the state of the engine, and an engine control unit that controls the engine, The engine control unit When the determination unit determines that the switching operation has been performed ,before The engine starts to burn the air-fuel mixture. ,and , the engine torque generated by the combustion is set to a minimum value of the engine torque in the normal mode or less. At the same time, when the vehicle is being driven in the special mode, variable rotation speed control is performed to change the engine rotation speed and engine torque based on the depression amount of the accelerator pedal. The present invention provides a hybrid vehicle characterized by the above.

[0008] In this configuration, when the switching operation is performed to operate in the special mode, the torque applied from the engine to the generator, and therefore the amount of power generated by the generator, is kept low, and the engine is operated in this state. Therefore, the engine can be driven while keeping the power supplied to the battery low, and the opportunity to operate in the special mode, that is, the opportunity to check the state of the engine, can be secured while preventing the battery from being overcharged. Furthermore, since the engine speed can be changed even when operating in the special mode, the engine speed required for investigating the engine condition can be realized.

[0009] In the above configuration, preferably, the engine control unit prohibits driving of the vehicle in the special mode if the SOC of the battery is equal to or higher than a predetermined judgment SOC, even if the judgment unit determines that the switching operation has been performed (Claim 2).

[0010] This configuration makes it possible to prevent the engine and generator from being driven and supplying power to the battery when the battery's SOC is high, thereby more reliably preventing the battery from being overcharged.

[0011] In the above configuration, preferably, the engine control unit prohibits driving of the vehicle in the special mode if the temperature of the battery is outside a predetermined range, even if the determination unit determines that the switching operation has been performed (claim 3).

[0012] This configuration prevents the vehicle from being operated in the special mode when the battery temperature is inappropriate, i.e., prevents the engine from running and the generator from starting to supply power to the battery, thereby preventing the battery from being charged when the battery temperature is inappropriate, which would accelerate battery deterioration.

[0015] In the above-described configuration, preferably, when the variable rotation speed control is performed, the engine control unit increases the engine rotation speed when the accelerator pedal depression amount is large compared to when the accelerator pedal depression amount is small, and decreases the engine torque when the engine rotation speed is high compared to when the engine rotation speed is low (see claim 4 ).

[0016] With this configuration, when operating in special mode, the engine speed is changed while the energy imparted from the engine to the generator is kept small, thereby reliably keeping the amount of power generated by the generator and the power supplied to the battery low.

[0017] In the above configuration, the condition for performing the variable rotation speed control is that the shift position of the transmission mounted on the vehicle is in a non-driving range (claim 5 ).

[0018] In the above configuration, the determination unit determines whether the shift position of a transmission mounted on the vehicle is in a driving range, and when the determination unit determines that the switching operation has been performed and the shift position is in a driving range, the engine control unit controls the engine speed and engine torque to constant speed and torque, respectively (see claims 6 ).

[0019] With this configuration, when the transmission is in the drive range and vehicle speed, rather than engine speed, is considered to be the determining factor for checking the engine status, i.e., when it is considered that there is no need to change the engine speed, the engine speed and engine torque are controlled to constant values, respectively, making it possible to appropriately check the engine status while maintaining a low level of power supplied to the battery. [Effects of the Invention]

[0020] As described above, the control device for a hybrid vehicle of the present invention can prevent the battery from being overcharged and ensure an opportunity to check the state of the engine. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing a schematic configuration of a hybrid vehicle according to an embodiment of the present invention; [Figure 2]FIG. 2 is a block diagram showing a control configuration of the vehicle. [Figure 3] 4 is a flowchart showing a procedure of engine control. [Figure 4] 4 is a graph showing the relationship between engine speed and engine torque under normal control. [Figure 5] 10 is a graph showing the relationship between the accelerator opening degree and the engine speed and engine torque in a second special mode. [Figure 6] 10 is a graph showing the relationship between the accelerator opening degree and the engine speed and engine torque in a first special mode. DETAILED DESCRIPTION OF THE INVENTION

[0022] (Overall vehicle configuration) Hereinafter, an embodiment of a hybrid vehicle according to the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram showing a schematic configuration of a hybrid vehicle 1 (hereinafter referred to as vehicle 1). Vehicle 1 is, for example, a four-wheeled automobile.

[0023] The vehicle 1 is equipped with a motor 10, an inverter 12, a high-voltage battery 14, an engine 16, a generator 18, a converter 20, a low-voltage battery 22, and a DC / DC converter 24. The vehicle 1 is also equipped with a driving force transmission device 27 including a transmission 26. The high-voltage battery 14 corresponds to the "battery" in the claims, and the generator 18 corresponds to the "electric generator" in the claims.

[0024] The high-voltage battery 14 is a battery that supplies power to each part of the vehicle 1, such as the motor 10. In this embodiment, the vehicle 1 is equipped with a Li battery (lithium battery) as the high-voltage battery 14.

[0025] The high-voltage battery 14 is provided with detection devices such as a battery current sensor SN1 that detects the current flowing through the high-voltage battery 14 and a battery temperature sensor SN2 that detects the temperature of the high-voltage battery 14.

[0026] The low-voltage battery 22 is a battery with a lower output voltage than the high-voltage battery 14. In this embodiment, a lead battery is mounted on the vehicle 1 as the low-voltage battery 22. For example, the high-voltage battery 14 has a nominal voltage of 24V, and the low-voltage battery 22 has a nominal voltage of 12V.

[0027] The DC / DC converter 24 is electrically provided between the high-voltage battery 14 and the low-voltage battery 22. The DC / DC converter 24 steps down the output voltage of the high-voltage battery 14 and supplies it to the low-voltage battery 3.

[0028] The motor 10 is mounted on the vehicle 1 as a driving source for traveling. The motor 10 rotates by receiving a supply of electric power from a high-voltage battery 14. The output of the motor 10 is transmitted to the wheels 2 via a driving force transmission device 27 while being changed in speed by a transmission 26. In this embodiment, the motor 10 is configured to also operate as a generator, and generates electric power by receiving the rotational force of the wheels 2 when the vehicle 1 is decelerating, for example, to regenerate deceleration energy.

[0029] The inverter 12 is electrically provided between the motor 10 and the high-voltage battery 14. The inverter 12 converts direct current from the high-voltage battery 14 into alternating current and supplies it to the motor 10, and also controls the frequency of the current supplied to the motor 10.

[0030] The generator 18 is a generator that generates electricity when rotated by the engine 16. The electric power generated by the generator 18 is supplied to the high-voltage battery 14, thereby charging the high-voltage battery 14. In this embodiment, an IPM motor is used as the generator 18.

[0031] The converter 20 is electrically provided between the generator 18 and the high-voltage battery 14. The converter 20 converts the AC current generated by the generator 18 into DC current and supplies it to the high-voltage battery 14.

[0032] As described above, the engine 16 is mounted on the vehicle 1 as a device for rotating and driving the generator 18 to generate electricity. The engine 16 has an engine body (not shown) formed with a combustion chamber into which fuel and air are introduced, and an output shaft (not shown) that rotates when the fuel-air mixture is burned in the combustion chamber. The output shaft of the engine 16 is connected to the generator 18, and the generator 18 rotates when the output shaft of the engine 16 rotates.

[0033] The amount of electricity generated by the generator 18 varies depending on the output of the engine 16. Specifically, the amount of electricity generated by the generator 18 varies in proportion to both the engine torque and the engine speed. In other words, the greater the product of the engine torque and the engine speed (= engine torque × engine speed), the greater the amount of electricity generated by the generator 18.

[0034] In this embodiment, engine 16 is a rotary piston engine that includes a rotor housing that functions as a combustion chamber and an eccentric shaft that serves as an output shaft. Engine 16 also includes a throttle valve 31 (FIG. 2) that is provided in an intake passage that communicates with the rotor housing and that can change the amount of intake air introduced into the rotor housing, an injector 32 (FIG. 2) that injects fuel into the rotor housing, and a spark plug 33 (FIG. 2) that ignites the air-fuel mixture formed in the rotor housing.

[0035] (Control Configuration) The control configuration of the vehicle 1 will be described with reference to the block diagram in Fig. 2. The vehicle 1 is equipped with multiple controllers that are configured with a CPU, ROM, RAM, etc. and control each part of the vehicle 1. In Fig. 2, the multiple controllers are collectively shown as a single controller 100.

[0036] The controller 100 is provided with various sensors in addition to the battery current sensor SN1 and battery temperature sensor SN2. Specifically, the vehicle 1 is provided with a shift sensor SN3 that detects the shift position of the transmission 26. The vehicle 1 is provided with an accelerator pedal 41 and a brake pedal 42 that are depressed by the driver, an accelerator position sensor SN4 that detects the accelerator position, which is the amount of depression of the accelerator pedal 41, and a brake pedal sensor SN5 that detects the ON / OFF (depressed or not) of the brake pedal 42. The controller 100 is sequentially supplied with information detected by these sensors SN1 to SN5 (battery current, battery temperature, shift position, accelerator position, and ON / OFF of the brake pedal 42). The vehicle 1 is also provided with a start switch SW1 that is operated by the driver, and an operation signal of the start switch SW1 is also input to the controller 100.

[0037] In this embodiment, when the start switch SW1 is pressed once, the state becomes ACC_ON, and power is supplied to electrical devices such as audio equipment installed in the vehicle 1, enabling the use of the electrical devices. When the start switch SW1 is pressed twice, the state becomes IG_ON, and power is supplied to each part of the engine 16, enabling the engine 16 to start. When the start switch SW1 is pressed three times, the state becomes so-called Ready_ON, enabling the motor 10 to rotate, and thus enabling the vehicle 1 to travel.

[0038] The controller 100 executes various determinations and calculations based on the input information, and controls each part of the vehicle 1. Specifically, the controller 100 is electrically connected to the throttle valve 31, the injector 32, the spark plug 33, the inverter 12, the generator 18, etc. of the engine 16, and outputs control signals to each of these devices based on the results of the calculations, etc.

[0039] The controller 100 operates so as to functionally include a determination unit 101 and an engine control unit 102 by executing a predetermined program.

[0040] The engine control unit 102 controls the engine 16. Specifically, the engine control unit 102 changes the throttle opening, which is the opening of the throttle valve 31, the fuel injection amount, which is the amount of fuel injected from the injector 32, and the ignition timing, which is the timing at which the spark plug 33 performs ignition, to change the combustion energy generated in the engine 16.

[0041] The determination unit 101 determines whether a predetermined switching operation has been performed to switch the driving mode of the vehicle 1 from the normal mode to the special mode. The normal mode is a driving mode for normal driving. The special mode is a driving mode for investigating the state of the engine 16. The special mode is selected, for example, during maintenance of the vehicle 1, certification, pre-shipment inspection, etc. In this embodiment, operations on the accelerator pedal 41 and the brake pedal 45 that are unlikely to be performed during normal driving are pre-set as switching operations and stored in the determination unit 101. For example, the following operations are set as switching operations: the accelerator pedal 41 is depressed multiple times while the brake pedal 42 is depressed, then the accelerator pedal 41 is depressed multiple times while the brake pedal 42 is not depressed, and then the accelerator pedal 41 is depressed multiple times while the brake pedal 42 is depressed.

[0042] The special modes further include a first special mode that is adopted when engine 16 is driven while vehicle 1 is stopped (while wheels 2 are stopped from rotating), and a second special mode that is adopted when engine 16 is driven while wheels 2 are rotating on rollers to simulate vehicle 1 traveling. When determining that a switching operation has been performed, that is, when a special mode has been selected as the driving mode of vehicle 1, determination unit 101 further determines whether an operation to select the first special mode or the second special mode has been performed as the driving mode of vehicle 1.

[0043] When the shift position of transmission 26 is in P range (parking range) or N range (neutral range), the transmission of power to wheels 2 is restricted and vehicle 1 is maintained in a stopped state. Thus, an operation of shifting transmission 26 to P range or N range is set as an operation of selecting a first special mode, and an operation of shifting transmission 26 to a range other than P or N, i.e., a forward range such as D range (drive range) or R range (reverse range), is set as an operation of selecting a second special mode, and determination unit 101 determines whether the shift position of transmission 26 is in P range or N range. P range and N range correspond to "non-driving ranges" in the claims, and a forward range such as D range and R range correspond to "driving ranges" in the claims.

[0044] The first special mode is implemented to measure the exhaust noise of the engine 16 during certification and inspection of the vehicle 1. In addition, the first special mode is also implemented to check for malfunctions in the engine 16 during maintenance of the vehicle 1 and to confirm that the engine 16 starts properly after repairs. Here, the measurement of the exhaust noise of the engine 16 requires that the engine speed be set to a predetermined speed. Furthermore, depending on the type of malfunction of the engine 16, it may be necessary to change the engine speed of the engine 16 in order to reproduce the malfunction or to confirm that the repair has been carried out properly. For this reason, the first special mode allows the engine speed to be changed, as will be described later.

[0045] The second special mode is implemented to measure the negative pressure in the crankcase during inspection of the vehicle 1. The second special mode is also implemented during EMC testing during certification of the vehicle 1. Here, the above-mentioned negative pressure measurement and EMC testing require the vehicle to run at a predetermined speed. Therefore, the second special mode is implemented when the engine 16 is driven while the vehicle 1 is running in a simulated driving state, as described above.

[0046] (Engine control) Next, a description will be given of engine control performed by the controller 100. Fig. 3 is a flowchart showing the procedure of engine control performed by the controller 100.

[0047] First, the controller 100 determines whether or not IG_ON has been set (step S1). As described above, in this embodiment, IG_ON is set when the start switch SW1 is pressed twice. Thus, the controller 100 determines that IG_ON has been set when the start switch SW1 is pressed twice. This determination is made based on the signal from the start switch SW1.

[0048] If the determination in step S1 is NO, i.e., IG_ON, the controller 100 repeats step S1. On the other hand, if the determination in step S1 is YES, i.e., IG_ON, the controller 100 proceeds to step S2. In other words, the controller 100 waits for IG_ON before proceeding to step S2.

[0049] In step S2, the controller 100 determines whether or not the above-mentioned switching operation has been performed, based on the detected values ​​of the accelerator opening sensor SN4 and the brake pedal sensor SN5.

[0050] If the judgment in step S2 is NO and it is determined that a switching operation has not been performed, that is, if normal mode is selected as the driving mode of vehicle 1, controller 100 sets the driving mode of vehicle 1 to normal mode and performs normal control, which is engine control for normal driving.

[0051] In normal control, the controller 100 determines whether to start the engine 16 based on the accelerator opening and the battery SOC (State Of Charge) of the high-voltage battery 14. For example, if the accelerator opening is equal to or greater than a predetermined value and the power consumption of the motor 10 is large, or if the battery SOC is equal to or less than a predetermined value and power supply to the high-voltage battery 14 is necessary, the controller 100 determines to start the engine 16.

[0052] Here, the controller 100 calculates the amount of increase or decrease in the battery SOC per unit time based on the battery current detected by the battery current sensor SN1, and calculates (estimates) the battery SOC by integrating this amount.

[0053] Furthermore, in normal control, controller 100 sets a target power generation amount, which is a target value for the amount of power generation of generator 18, in accordance with the accelerator position and battery SOC, and sets a target output, which is the output of engine 16 required to achieve this target power generation amount. Furthermore, controller 100 sets a normal target engine speed, which is a target value for the engine speed in normal control, and a normal target engine torque, which is a target value for the engine torque, based on the set target output, and controls throttle valve 31, injector 32, spark plugs, etc. so that these normal target engine speeds and normal target engine torques are achieved. Specifically, the normal target engine speeds and normal target engine torques corresponding to the respective target outputs are predetermined and stored in controller 100 as a map or the like, and controller 100 extracts each value corresponding to the set target output from this map or the like and sets them as the normal target engine speed and normal target engine torque.

[0054] Here, the normal target engine speed and the normal target engine torque are each set to values ​​that can achieve the target output, allow the engine 16 to rotate stably, and increase the thermal efficiency of the engine 16. FIG. 4 is a graph showing the normal target engine speed and the normal target engine torque. In FIG. 4, the target output (engine output) increases toward the tip of the arrow Y1. As shown in FIG. 4, when the target output is equal to or less than a predetermined first output (within the range A1), the normal target engine speed is maintained near the normal target engine speed when the target output is minimum at a predetermined reference speed Nmin, regardless of the target output, and only the normal target engine torque is increased in accordance with an increase in the target output. Furthermore, when the target output is higher than the first output and equal to or less than a second output (second output > first output) (within the range A2), the normal target engine speed is increased from the reference speed Nmin in accordance with an increase in the target output, and the normal target engine torque is also increased in accordance with an increase in the target output. Furthermore, when the target output is higher than the second output (in the range A3), the engine torque is maintained near the maximum torque Tmax regardless of the target output, and the normal target engine speed is increased in accordance with the increase in the target output.

[0055] The above normal control continues until Ready_OFF or IG_OFF is reached.

[0056] Returning to step S2, if the determination in step S2 is YES and it is determined that a switching operation has been performed, that is, if the special mode has been selected as the driving mode of the vehicle 1, the controller 100 determines whether Ready_ON has been entered (step S3). As described above, in this embodiment, after the start switch SW1 is pressed twice to enter IG_ON, the controller 100 enters Ready_ON when the start switch SW1 is pressed once more. Thus, the controller 100 determines whether Ready_ON has been entered based on the signal from the start switch SW1.

[0057] If the determination in step S3 is NO and Ready_ON has not been achieved, the controller 100 repeats step S3. On the other hand, if the determination in step S3 is YES and Ready_ON has been achieved, the controller 100 proceeds to step S4. That is, the controller 100 waits for Ready_ON to be achieved before proceeding to step S4.

[0058] In step S4, the controller 100 determines whether the battery SOC is less than a predetermined determination SOC. The determination SOC is set in advance and stored in the controller 100. The determination SOC is set to, for example, about 80%.

[0059] If the determination in step S4 is NO and the battery SOC is equal to or greater than the determination SOC, the process proceeds to step S20, where the controller 100 performs the normal control described above.

[0060] On the other hand, if the determination in step S4 is YES and the battery SOC is less than the determination SOC, the controller 100 determines whether the battery temperature, which is the temperature of the high-voltage battery 14, is equal to or greater than a predetermined first temperature and equal to or less than a predetermined second temperature (step S5). The controller 100 makes this determination based on the detected value of the battery temperature sensor SN2. The first temperature and the second temperature are set in advance and stored in the controller 100. The first temperature is set to the lower limit of the temperature at which the high-voltage battery 14 can be appropriately charged, and the second temperature is set to the upper limit of the temperature at which the high-voltage battery 14 can be appropriately charged. For example, the first temperature is set to about 0°C, and the second temperature is set to about 50°C. Here, the range of the battery temperature, equal to or greater than the first temperature and equal to or less than the second temperature, corresponds to the "predetermined range" in the claims.

[0061] If the determination in step S5 is NO, that is, the battery temperature is lower than the first temperature or higher than the second temperature, the process proceeds to step S20, where the controller 100 performs the above-described normal control.

[0062] On the other hand, if the determination in step S5 is YES and the battery temperature is equal to or higher than the first temperature and equal to or lower than the second temperature, the controller 100 determines whether the shift position of the transmission 26 is one of the P range (parking range) and the N range (neutral range) (step S6).

[0063] If the determination in step S6 is NO and the shift position of the transmission 26 is determined to be neither P range nor N range, that is, if the shift position is a forward range such as D range or R range, the controller 100 operates the vehicle 1 in the second special mode (step S40).

[0064] In the second special mode, first, the controller 100 starts the engine 16 when the accelerator pedal 41 is depressed and the accelerator opening becomes equal to or greater than the operation start opening ACC1, which is slightly larger than 0% (step S31). That is, the controller 100 starts fuel injection from the injector 32 and ignition from the spark plug 33, thereby starting combustion of the fuel-air mixture in the engine 16. In addition, in the second special mode, the controller 100 controls the generator 18, the throttle valve 31, the injector 32, and the spark plug 33 so that the engine speed and engine torque are maintained constant (step S42).

[0065] Figure 5 is a graph showing the relationship between the accelerator opening and the engine speed and engine torque in the second special mode. As shown in Figure 5, in the second special mode, when the accelerator opening is equal to or greater than the starting opening ACC1, the engine speed and engine torque are set to values ​​higher than 0 due to the combustion of the air-fuel mixture in the engine 16. Also, in the second special mode, when the accelerator opening is equal to or greater than the starting opening ACC1, the engine speed and engine torque are maintained at constant values ​​regardless of the accelerator opening.

[0066] In the second special mode (when the accelerator pedal position is equal to or greater than the operation start position ACC1), the controller 100 controls the engine speed and engine torque to the minimum values ​​of the engine speed and engine torque at point P1 in Fig. 4, that is, the minimum values ​​of the engine speed and engine torque under normal control (normal mode). That is, in the second special mode, the controller 100 controls the engine speed to the above-mentioned reference engine speed Nmin, regardless of the accelerator pedal position, and controls the engine torque to the reference torque Pmin, which is the minimum value of the engine torque that can be achieved under normal control.

[0067] The operation in this second special mode continues until Ready_OFF is reached (until the start switch SW1 is pressed).

[0068] As described above, when driving in the second special mode, there are cases where the vehicle speed needs to be set to a predetermined speed. In response to this, the controller 100 changes the vehicle speed by changing the rotation speed of the motor 10 in accordance with the accelerator opening.

[0069] Returning to step S6, if the determination in step S6 is YES and the shift position of the transmission 26 is determined to be in the P range or the N range, the controller 100 drives the vehicle 1 in the first special mode (step S30).

[0070] In the first special mode, as in the second special mode, when the accelerator pedal 41 is depressed and the accelerator opening becomes equal to or greater than the operation start opening ACC1, the controller 100 starts the engine 16 by initiating combustion of the air-fuel mixture (step S31). Meanwhile, in the first special mode, the controller 100 changes the engine speed and engine torque in accordance with the accelerator opening (step S32). Specifically, the controller 100 changes the power generation torque of the generator 18 in accordance with the accelerator opening, thereby changing the engine speed. Furthermore, the controller 100 changes the throttle opening, fuel injection amount, and ignition timing in accordance with the accelerator opening, thereby changing the engine torque.

[0071] Fig. 6 is a graph showing the relationship between the accelerator opening and the engine speed and engine torque in the first special mode. As shown in Fig. 6, in the first special mode, as in the second special mode, when the accelerator opening is equal to or greater than the operation start opening ACC1, the engine speed and engine torque are set to values ​​higher than 0 due to combustion of the air-fuel mixture in engine 16.

[0072] On the other hand, in the first special mode, the engine speed is set higher when the accelerator pedal is opened widely than when it is opened narrowly, and the engine torque is set lower when the accelerator pedal is opened widely than when it is opened narrowly, and lower when the engine speed is high than when it is low.

[0073] Specifically, even in the first special mode, if the accelerator opening is equal to or greater than the start-of-operation opening ACC1 and less than the predetermined switching opening ACC2, the engine speed is maintained at the above-mentioned reference speed Nmin and the engine torque is maintained at the above-mentioned reference torque Tmin, regardless of the accelerator opening, as in the second special mode.

[0074] On the other hand, in the first special mode, when the accelerator opening is equal to or greater than the switching opening ACC2, the engine speed increases as the accelerator opening increases. Once the accelerator opening exceeds the switching opening ACC2, the engine speed increases from the reference rotational speed Nmin as the accelerator opening increases. In the example of FIG. 6, the engine speed increases in proportion to the accelerator opening. Also, in the first special mode, when the accelerator opening is equal to or greater than the switching opening ACC2, the engine torque decreases as the accelerator opening increases. Once the accelerator opening exceeds the switching opening ACC2, the engine torque is reduced from the reference torque Tmin as the accelerator opening increases. In the example of FIG. 6, the engine torque is reduced in proportion to the accelerator opening. Here, in this way, in the first special mode, the engine torque is controlled to the reference torque Tmin or a value smaller than the reference torque Tmin, and in the first special mode, the engine torque is kept below the reference torque Tmin.

[0075] In this embodiment, maps corresponding to the graph of Fig. 6, namely, a map of accelerator opening and engine speed and a map of engine speed and engine torque, are predetermined and stored in controller 100. Controller 100 extracts the engine speed and engine torque corresponding to the accelerator opening from these maps as the target engine speed and target engine torque, respectively. Controller 100 then controls generator 18 to achieve the target engine speed, and controls throttle valve 31, injector 32, and spark plug 33 to achieve the target engine torque.

[0076] The control in step S32 above, that is, the control for changing the engine speed and engine torque based on the accelerator opening degree, corresponds to the "variable speed control" in the claims.

[0077] The control in the second special mode is continued until Ready_OFF is reached (until the start switch SW1 is pressed).

[0078] As described above, in the first special mode, the engine speed is required to be set to a predetermined speed. In response to this, the controller 100 changes the engine speed in accordance with the accelerator opening, and when the vehicle 1 is driven in the first special mode, the engine speed is changed by changing the amount of depression of the accelerator pedal 41 by the driver.

[0079] (action, etc.) As described above, in the above embodiment, when operation of the vehicle 1 in the special modes (first special mode and second special mode) begins, the engine 16 is started and combustion of the air-fuel mixture in the engine 16 begins. When the vehicle 1 is operated in the first special mode, the engine torque is maintained at the reference torque Tmin. When the vehicle 1 is operated in the second special mode, the engine torque is set to be equal to or lower than the reference torque Tmin. As described above, the reference torque Tmin is the minimum value of the engine torque achieved under normal control (normal mode). Thus, in the above embodiment, when the vehicle 1 is operated in the special mode, the engine torque is set to the minimum value of the engine torque achieved in the normal mode or a torque lower than the minimum value. If the engine torque is kept low, the amount of power generated by the generator 18 can also be kept low. Therefore, according to the above embodiment, when the vehicle 1 is operated in the special mode, the increase in the amount of power generated by the generator 18, i.e., the amount of charge of the high-voltage battery 14, can be kept low while driving the engine 16. This makes it possible to prevent overcharging of the high-voltage battery 14 while ensuring an opportunity to inspect the condition of the engine 16.

[0080] In particular, in the above embodiment, when the vehicle 1 is operated in the second special mode, the engine torque is maintained at the reference torque Tmin, and the engine speed is maintained at the reference speed Nmin, which is the minimum engine speed achieved in the normal mode. This keeps the output of the engine 16 low, thereby minimizing increases in the amount of power generated by the generator 18 and the amount of charge in the high-voltage battery 14. This makes it possible to more reliably inspect the condition of the engine 16 while preventing overcharging of the high-voltage battery 14.

[0081] In the above embodiment, when the vehicle 1 is driven in the first special mode, the engine speed is changed according to the accelerator pedal depression. Therefore, the engine speed can be changed to the speed required for the inspection, allowing for appropriate inspection. Furthermore, the engine speed is set higher when the accelerator pedal depression, i.e., the amount of depression of the accelerator pedal 41, is large than when it is small, so that the engine speed can be changed in accordance with the driver's operating feel.

[0082] Furthermore, when the vehicle 1 is operated in the first special mode, the engine torque is lower when the engine speed is high than when it is low. This makes it possible to prevent the engine output from increasing while increasing the engine speed. This reduces the amount of power generated by the generator 18, thereby reducing the amount of power supplied to the high-voltage battery 14.

[0083] Furthermore, in the above embodiment, even if it is determined that a switching operation has been performed (even if the determination in step S2 is YES), if the battery SOC is equal to or higher than the determined SOC (if the determination in step S4 is NO), normal control is implemented (step S20). That is, operation in the special mode is prohibited, and the control (steps S31, S41) of starting the engine 16 in response to depression of the accelerator pedal 41 is prohibited. This makes it possible to avoid the engine 16 and the generator 18 being driven and supplying power to the high-voltage battery 14 when the battery SOC is high, and more reliably prevents the high-voltage battery 14 from being overcharged.

[0084] Furthermore, in the above embodiment, even if it is determined that a switching operation has been performed (even if the determination in step S2 is YES), if the battery temperature is lower than the first temperature or higher than the second temperature (if the determination in step S5 is NO), normal control is implemented (step S20). That is, if the battery temperature is lower than the first temperature or higher than the second temperature, operation in the special mode is prohibited, and the control of starting the engine 16 in response to depression of the accelerator pedal 41 (steps S31 and S41) is prohibited. This makes it possible to prevent the vehicle 1 from operating in the special mode when the battery temperature is inappropriate, i.e., to prevent the engine 16 from being driven and power supply from the generator 18 to the high-voltage battery 14 from being started. This makes it possible to prevent the high-voltage battery 14 from being charged when the battery temperature is inappropriate, thereby accelerating deterioration of the high-voltage battery 14.

[0085] (Variation) In the above embodiment, the engine is a rotary piston engine, but the engine may be a reciprocating engine. Also, the high-voltage battery is not limited to a Li battery.

[0086] In addition, in the above embodiment, a case has been described in which the first special mode and the second special mode are set as the special mode, but only one of these two special modes may be set as the special mode.

[0087] Furthermore, the specific procedure for the switching operation for switching the operation mode from the normal mode to the special mode and the specific contents of the operation for selecting the first special mode or the second special mode are not limited to those described above.

[0088] In the above embodiment, it is determined in step S5 whether the battery temperature is equal to or higher than the first temperature and equal to or lower than the second temperature, but it may be determined whether the battery temperature is equal to or higher than the first temperature or whether the battery temperature is equal to or lower than the second temperature. Furthermore, the specific values ​​of the first temperature, the second temperature, and the specific value of the determination SOC are not limited to those described above.

[0089] In the above embodiment, when the vehicle is operated in the second special mode, the engine speed and engine torque are maintained constant regardless of the accelerator opening when the accelerator opening is less than the switching opening ACC2. However, the engine speed and engine torque may be changed in accordance with the accelerator opening even when the accelerator opening is less than the switching opening ACC2.

[0090] In addition, in the above embodiment, when operating in the second special mode, the engine speed is increased in proportion to the accelerator opening and the engine torque is reduced in proportion to the engine speed, but these relationships do not have to be proportional.

[0091] Furthermore, in the above embodiment, when the vehicle is operated in the second special mode, and the accelerator opening is equal to or greater than the switching opening ACC2, the engine torque is lower when the engine speed is high than when the engine speed is low. However, even when the accelerator opening is equal to or greater than the switching opening ACC2, the engine torque may be controlled to a constant reference torque Tmin regardless of the engine speed, just as when the accelerator opening is less than the switching opening ACC2.

[0092] In the above embodiment, when the vehicle is driven in the second special mode, the engine speed is set higher when the accelerator pedal depression is high than when it is low. However, the relationship between the accelerator pedal depression and the engine speed is not limited to the above as long as the engine speed is changed according to the accelerator pedal depression. However, if the engine speed is controlled so that it is higher when the accelerator pedal depression is high than when it is low, the vehicle can be made to match the driver's operating feel, improving operability.

[0093] In the above embodiment, the engine torque in the first special mode is set to the reference torque Tmin, i.e., the minimum value of the engine torque achieved in normal control (normal mode), but the engine torque in the first special mode may be set to be lower than the reference torque Tmin. Similarly, the engine torque may be set to be lower than the reference torque Tmin even when the accelerator opening in the second special mode is less than the switching opening ACC2. [Explanation of symbols]

[0094] 1 vehicle 10 Motor 14 High voltage battery (battery) 16 Engine 18 Generator 26 Transmission 41 Accelerator pedal 101 Judgment section 102 Engine control unit

Claims

1. a motor as a driving source for traveling; a battery that supplies power to the motor; an engine having a combustion chamber in which an air-fuel mixture is burned; a generator driven by the engine to generate electricity and charge the battery; an accelerator pedal operated by a driver; a determination unit that determines whether a predetermined switching operation has been performed to switch the driving mode of the vehicle from a normal mode for normal driving to a special mode for checking the state of the engine; an engine control unit that controls the engine, The engine control unit When the determination unit determines that the switching operation has been performed, the engine is caused to start combustion of the air-fuel mixture, and the engine torque generated by the combustion is set to a minimum value of the engine torque in the normal mode or less; A hybrid vehicle characterized in that, when the vehicle is driven in the special mode, variable engine speed control is performed to change engine speed and engine torque based on the amount of depression of the accelerator pedal.

2. 2. The hybrid vehicle according to claim 1, The engine control unit prohibits driving of the vehicle in the special mode when the SOC of the battery is equal to or greater than a predetermined judgment SOC, even if the judgment unit determines that the switching operation has been performed.

3. 2. The hybrid vehicle according to claim 1, The engine control unit prohibits driving of the vehicle in the special mode if the temperature of the battery is outside a predetermined range, even if the determination unit determines that the switching operation has been performed.

4. 2. The hybrid vehicle according to claim 1, When the variable rotation speed control is performed, the engine control unit increases the engine rotation speed when the accelerator pedal is depressed more than when it is depressed less, and decreases the engine torque when the engine rotation speed is high compared to when it is low.

5. 2. The hybrid vehicle according to claim 1, the determination unit determines whether a shift position of a transmission mounted in the vehicle is in a non-driving range; When the determination unit determines that the switching operation is performed and the shift position is in a non-driving range, the engine control unit performs the variable rotation speed control.

6. The hybrid vehicle according to any one of claims 1 to 5, the determination unit determines whether a shift position of a transmission mounted on the vehicle is in a driving range, When the determination unit determines that the switching operation is performed and the shift position is in the driving range, the engine control unit controls the engine speed and engine torque to constant speed and torque, respectively.

7. A motor as a driving source for traveling; a battery that supplies power to the motor; an engine having a combustion chamber in which an air-fuel mixture is burned; a generator driven by the engine to generate electricity and charge the battery; a determination unit that determines whether a predetermined switching operation has been performed to switch the driving mode of the vehicle from a normal mode for normal driving to a special mode for checking the state of the engine; an engine control unit that controls the engine, the determination unit determines whether a shift position of a transmission mounted on the vehicle is in a driving range, The engine control unit When the determination unit determines that the switching operation has been performed, the engine is caused to start combustion of the air-fuel mixture, and the engine torque generated by the combustion is set to a minimum value of the engine torque in the normal mode or less; When the switching operation is performed and the determination unit determines that the shift position is in the driving range, the engine speed and engine torque are controlled to constant speed and torque, respectively.

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