Hybrid vehicle

Abstract

Disclosed is a hybrid vehicle (1) comprising an engine (2), a motor (3), a generator (4), and a control device (10) that controls an operation state of at least the engine (2), and that carries out series travel of traveling by a driving force of the motor (3) while causing the generator (4) to generate power by a driving force of the engine (2). The hybrid vehicle (1) has a normal mode in which a driver request output is set according to an accelerator position, and a sport mode in which a driver request output greater than or equal to that set in the normal mode is set according to the accelerator position. During the series travel, the control device (10) makes a first minimum rotation speed (ω1) of the engine (2) in the sport mode greater than a second minimum rotation speed (ω2) of the engine (2) in the normal mode.

Description

Technical Field

[0001] This invention relates to a hybrid vehicle that performs series driving.

Background Art

[0002] Conventionally, a hybrid vehicle equipped with an engine, a motor, and a generator and performing series driving is known. In series driving, while generating electricity in a generator with the driving force of the engine, the motor is operated using the generated electric power or battery power to generate the driving force of the vehicle. The operating state of the engine during series driving is controlled in consideration of, for example, fuel efficiency and quietness. Thereby, an effect of extending the cruising range of the vehicle and an effect of improving the quiet performance can be realized (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent hybrid vehicles, there are some in which a driver can select a preferred mode from among a plurality of drive modes. A drive mode means a type of driving characteristics and running characteristics of a vehicle (a pattern of the characteristics of the vehicle behavior with respect to the driving operation of the driver). Specific examples of drive modes include a normal mode and a sports mode. The driving characteristics and running characteristics of the vehicle in each mode are controlled to have characteristics suitable for that mode. For example, in the sports mode, the driver required output with respect to the accelerator opening is set to a larger value compared to the normal mode. Thereby, for the same accelerator operation, the engine and the motor are controlled to output a larger output, so that the acceleration response is improved and a powerful and brisk running is realized.

[0005] On the other hand, when applying the sports mode as described above to the series driving of a hybrid vehicle, since the driver required output set at the time of a sudden increase in the accelerator opening tends to become excessive, it is difficult to make the actual engine output follow the increase in the driver required output, and there is a problem that it is difficult to obtain good acceleration response. In particular, in order to suppress the noise and vibration generated from the engine, when the engine rotation speed at the time of accelerator off is set relatively low, the time lag until the engine rotation speed is sufficiently increased becomes large, and the acceleration response immediately after the accelerator is turned on deteriorates.

[0006] One of the objects of the present case is devised in view of the above problems, and it is to provide a hybrid vehicle capable of improving the acceleration response during series driving in the sports mode. Note that not limited to this object, the operational effects derived from each configuration shown in the "Mode for Carrying Out the Invention" described later and not achievable by the conventional technology are also positioned as other objects of the present case.

Means for Solving the Problems

[0007] The disclosed hybrid vehicle can be realized as the aspects or application examples disclosed below and solves at least part of the above problems. The disclosed hybrid vehicle includes an engine, a motor, a generator, and a control device that controls at least the operating state of the engine, and is a hybrid vehicle that performs series driving in which the generator is caused to generate electricity by the driving force of the engine and travels by the driving force of the motor. The hybrid vehicle has a normal mode in which a driver required output corresponding to an accelerator opening is set, and a sports mode in which a driver required output greater than or equal to the size set in the normal mode is set according to the accelerator opening. When performing the series driving, the control device makes the first minimum rotation speed of the engine in the sports mode higher than the second minimum rotation speed of the engine in the normal mode, and makes the output of the engine and the generated power of the generator the same in the sports mode and the normal mode when the accelerator is off.

Effect of the Invention

[0008] According to the disclosed hybrid vehicle, the engine is controlled so that the first minimum rotation speed of the engine in the sports mode is higher than the second minimum rotation speed of the engine in the normal mode. That is, the minimum rotation speed of the engine in the sports mode is controlled to be higher compared to the normal mode. Thereby, when the accelerator pedal is depressed, the engine rotation speed can be increased to a desired speed in a relatively short time. Therefore, in the series driving in the sports mode, the acceleration response immediately after the accelerator is turned on can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0010] The disclosed hybrid vehicle can be implemented by the following examples.

Examples

[0011] [1. Device Configuration] FIG. 1 is a block diagram exemplifying the configuration of a hybrid vehicle 1 as an example. This hybrid vehicle 1 (also simply referred to as vehicle 1) is a hybrid automobile (hybrid electric vehicle, HEV, Hybrid Electric Vehicle) or a plug-in hybrid automobile (plug-in hybrid electric vehicle, PHEV, Plug-in Hybrid Electric Vehicle) equipped with an engine 2 and a motor 3 as drive sources, a generator 4 as a power generation device, and a battery 5 as a power storage device. A plug-in hybrid automobile means a hybrid automobile capable of external charging of the battery 5 or external power supply from the battery 5. The plug-in hybrid automobile is provided with a charging port (inlet) for inserting a charging cable through which electric power is supplied from an external charging facility and an outlet for external power supply.

[0012] The engine 2 is an internal combustion engine such as a gasoline engine or a diesel engine, for example. A generator 4 is connected to the drive shaft of the engine 2. The generator 4 is a generator (motor-generator) having both a function of driving the engine 2 with the power of the battery 5 and a function of generating electricity using the driving force of the engine 2. The generated electric power of the generator 4 is used for driving the motor 3 and charging the battery 5. A transmission mechanism (not shown) may be interposed on the power transmission path connecting the engine 2 and the generator 4.

[0013] The motor 3 is an electric motor (motor - generator) that has both the function of driving the vehicle 1 using the power of the battery 5 and the generated power of the generator 4, and the function of charging the battery 5 with the power generated by regenerative power generation. The battery 5 is a secondary battery such as a lithium - ion secondary battery or a nickel - metal hydride battery, for example. The drive shaft of the motor 3 is connected to the drive wheels of the vehicle 1. A transmission mechanism (not shown) may be interposed on the power transmission path connecting the motor 3 and the drive wheels.

[0014] A clutch 6 is interposed on the power transmission path connecting the engine 2 and the motor 3. The engine 2 is connected to the drive wheels via the clutch 6, and the motor 3 is disposed on the drive - wheel side of the clutch 6. Also, the generator 4 is connected on the engine 2 side of the clutch 6. When the clutch 6 is disengaged (released), the engine 2 and the generator 4 are in a non - connected state with respect to the drive wheels, and the motor 3 is in a connected state with respect to the drive wheels. Therefore, for example, by operating only the motor 3, "EV running (motor - only running)" is realized. In addition to this, by operating the engine 2 to generate electricity in the generator 4, "series running" is realized. Series running means running using the driving force of the motor 3 while generating electricity in the generator 4 with the driving force of the engine 2.

[0015] On the other hand, when the clutch 6 is engaged (fastened), the three components of the engine 2, the motor 3, and the generator 4 are in a connected state with respect to the drive wheels. Therefore, for example, by operating only the engine 2, "engine running (engine - only running)" is realized. In addition to this, by driving the motor 3 or the generator 4, "parallel running" is realized. Both the above - mentioned series running and parallel running are also called "hybrid running".

[0016] The operating states of the engine 2, motor 3, generator 4, battery 5, and clutch 6 are controlled by the control device 10. The control device 10 is a computer (electronic control unit, ECU, Electronic Control Unit) having a function of controlling at least the operating state of the engine 2. The control device 10 incorporates a processor (arithmetic processing unit) and a memory (storage device). The content of the control (control program) implemented by the control device 10 is stored in the memory, and the content is executed by being appropriately read into the processor.

[0017] A drive mode selector 7 is connected to the control device 10 of this embodiment. The drive mode selector 7 is a selection device that a driver of the vehicle 1 operates to select one of a plurality of drive modes, and is disposed in an instrument panel part or around the steering wheel that is easily accessible from the driver's seat. Information on the type of drive mode set by operating the drive mode selector 7 is transmitted to the control device 10.

[0018] The drive mode means a type of driving characteristics and running characteristics of the vehicle 1 (a formalization of the characteristics of the vehicle behavior with respect to the driver's driving operation). Specific examples of the drive mode include a normal mode (ordinary mode), a sports mode (paved road mode), a snow mode (snowy road mode), a gravel mode (rough road mode), an eco mode (energy-saving mode), and the like. The driving characteristics and running characteristics of the vehicle 1 are controlled to have characteristics suitable for the selected mode. Basically, the driver selects a preferred mode for the drive mode, but one of the modes may be automatically selected when a predetermined driving condition is satisfied.

[0019] As specific driving characteristics and running characteristics in each drive mode, various known characteristics can be adopted. For example, in the sports mode, compared with other modes including the normal mode, the driver-requested output with respect to the accelerator opening is set to a large value. With this setting, the acceleration response to the same accelerator operation is enhanced, and a powerful and brisk running is realized. Also, in the sports mode, compared with other modes including the normal mode, the maximum allowable driving force difference between the left and right wheels is set to a relatively large value. With this setting, the maximum value of the yaw moment that may occur during turning increases, and the turning performance is improved.

[0020] In the snow mode, compared with other modes including the normal mode, for example, the upper limit values of the driving force and the braking force are set small, or the maximum allowable driving force difference between the left and right wheels is set to a relatively small value. With these settings, the running stability on a slippery road surface is improved. In the gravel mode, compared with other modes including the normal mode, for example, the ratio of the rotational speed of the driving wheels to the drive source (transmission ratio, reduction ratio) is set to a relatively large value. With this setting, the torque of the driving wheels increases, and the performance of traversing rough roads is improved. In the eco mode, compared with other modes including the normal mode, for example, the rotational speed, torque, output (electric power), etc. are set so that the operating states of the engine 2, the motor 3, and the generator 4 are within a relatively high-efficiency operating range. With such settings, the fuel consumption of the engine 2 and the electricity cost of the motor 3 and the generator 4 are improved, and the cruising range is extended.

[0021] Also, an accelerator opening sensor 8 and a vehicle speed sensor 9 are connected to the control device 10 of the present embodiment. The accelerator opening sensor 8 is a sensor that detects a parameter (such as accelerator opening, accelerator pedal stroke, throttle opening) corresponding to the depression amount of the accelerator pedal. The vehicle speed sensor 9 is a sensor that detects the running speed (vehicle speed) of the vehicle 1. The information detected by these sensors 8 and 9 is transmitted to the control device 10.

[0022] FIG. 2 is a graph illustrating a characteristic that defines the relationship between the accelerator opening [%] detected by the accelerator opening sensor 8 and the driver required output [kW] set by the control device 10. The accelerator opening is the amount of depression of the accelerator pedal (for example, the accelerator pedal stroke or the rotation angle with respect to the fulcrum of the accelerator pedal, etc.) expressed as a percentage. Also, the driver required output is a parameter corresponding to the magnitude of the output (in other words, horsepower, electric power, or work rate) required by the driver to drive the vehicle 1. The output of the drive source of the vehicle 1 is controlled to correspond to the driver required output.

[0023] In both the normal mode and the sports mode, the driver required output is set according to the accelerator opening. The solid line in FIG. 2 shows the characteristic in the sports mode, and the dashed line shows the required output characteristic in the normal mode. In the normal mode, as shown by the dashed line in FIG. 2, when the accelerator opening is 0 [%], the driver required output is 0. Also, a driver required output that is approximately proportional to the accelerator opening is set. On the other hand, in the sports mode, a driver required output that is the same as or greater than that in the normal mode is set. That is, the value of the driver required output set in the sports mode is set to be equal to or greater than the value of the driver required output set in the normal mode at the same accelerator opening.

[0024] Also, in FIG. 2, the values of the driver required output set in the sports mode and the values of the driver required output set in the normal mode are the same only when the accelerator opening is 0 [%] (accelerator off) and 100 [%] (full throttle). At accelerator openings other than these, the driver required output in the sports mode is always set to be greater than the driver required output in the normal mode.

[0025] [2. Control Configuration] When the control device 10 performs series driving in the sports mode, it performs two types of controls on the engine 2 in order to improve the acceleration response of the vehicle 1 to a sudden increase in the accelerator opening. The first control is a control in which the engine 2 is operated with the engine speed [rpm] (the number of engine revolutions per unit time) set in advance to be higher from before the accelerator opening suddenly increases (from the accelerator-off state). The second control is a control in which, in a situation where the engine speed increases due to an increase in the accelerator opening, the maximum value of the increase rate, which is the time change gradient of the engine speed, is made larger in the sports mode than in the normal mode.

[0026] The first control will be described. First, the minimum value (the lowest value) of the engine speed in the sports mode is defined as the first minimum speed ω 1 and the minimum value (the lowest value) of the engine speed in the normal mode is defined as the second minimum speed ω 2 In the first control, as shown in FIG. 3, the operating state of the engine 2 is controlled so that the first minimum speed ω 1 is higher than the second minimum speed ω 2 .

[0027] The first control is performed when the accelerator pedal is not depressed (before the time t 0 ). At this time, the output (the product of torque and speed) of the engine 2 is controlled to be substantially the same in the sports mode and the normal mode. That is, in the first control, compared with the normal mode, instead of the first minimum speed ω 1 of the engine 2 in the sports mode being high, the torque of the engine 2 is controlled to be in a small state. The speed and torque of the engine 2 can be changed by adjusting the load on the generator 4 with respect to the engine 2 (the power that the generator 4 converts into electric power).

[0028] In the first control, since the output of the engine 2 is substantially the same in the sports mode and the normal mode, the power generation power of the generator 4 and the output of the motor 3 are also controlled to be the same in the sports mode and the normal mode. The output of the motor 3 is controlled to a magnitude corresponding to the power generation power of the generator 4 so as not to consume the battery power stored in the battery 5, for example. Further, the power generation power of the generator 4 is controlled to be a constant value corresponding to the output of the engine 2, for example. Generally, the maximum value of the power generation power of the generator 4 increases in proportion to the rotational speed of the generator 4 (i.e., the engine rotational speed). Therefore, the power generation state of the generator 4 in the sports mode has a large margin compared to the normal mode, and it is easy to increase the power generation power.

[0029] First minimum rotational speed ω 1 The value of may be a fixed value set in advance, or may be a variable value set according to the running state of the vehicle 1. First minimum rotational speed ω 1 When is a variable value, the first minimum rotational speed ω may be set according to the vehicle speed detected by the vehicle speed sensor 9. 1 For example, as shown by the solid line in FIG. 4, the lower the vehicle speed, the higher the first minimum rotational speed ω 1 may be. With such a setting, the acceleration response from the stop state or the low-speed running state is improved, and sporty driving is easily realized.

[0030] On the other hand, as shown by the two-dot chain line in FIG. 4, the higher the vehicle speed, the higher the first minimum rotational speed ω 1 may be. With such a setting, the noise and vibration of the engine 2 in the stop state or the low-speed running state are reduced, and quiet driving is easily realized. The broken line in FIG. 4 is the second minimum rotational speed ω 2 . The first minimum rotational speed ω 1 is preferably set higher than the second minimum rotational speed ω 2 for all vehicle speeds.

[0031] Next, the second control will be described. First, in a situation where the vehicle is in series driving and the driver demand output is not zero (a situation where the accelerator opening is not zero and at least the accelerator is on), the maximum increase rate of the engine 2 rotation speed in the sports mode is defined as the first increase rate G 1 In addition, in a situation where the vehicle is in series driving and the driver demand output is not zero, the maximum increase rate of the engine 2 rotation speed in the normal mode is defined as the second increase rate G 2 and defined as follows.

[0032] In the second control, as shown in FIG. 3, the operating state of the engine 2 is controlled so that the first increase rate G 1 is greater than the second increase rate G 2 . The second control is implemented after the time t 0 when the accelerator pedal is fully depressed. At this time, for example, by increasing the fuel injection amount or the intake air amount of the engine 2, or by optimizing the ignition timing, the increase rate of the engine 2 rotation speed increases. As a result, as shown in FIG. 3, the rising gradient of the solid line graph becomes steeper compared to the rising gradient of the broken line graph. That is, the engine rotation speed reaches the target rotation speed ω TGT in a short time, and the generated power by the generator 4 also increases in a short time.

[0033] [3. Flowchart] FIG. 5 is an example of a flowchart showing the flow of the above first control and second control. The control shown in this flowchart is repeatedly executed at a predetermined cycle inside the control device 10 when, for example, the power switch of the vehicle 1 (not shown) is on and the vehicle is drivable (in the READY state). In the vehicle 1 where this control is implemented, assume that either the sports mode or the normal mode is set as the drive mode. Steps A2 to A6 are the flow corresponding to the first control, and steps A7 to A12 are the flow corresponding to the second control.

[0034] In step A1, it is determined whether the vehicle 1 is in series driving. Series driving is automatically performed, for example, when the charging rate of the battery 5 is equal to or lower than a predetermined value, or when the vehicle 1 approaches an uphill slope. Alternatively, it is also performed when the driver desires series driving (when there is such an operation input). As specific implementation conditions and start conditions for series driving, known conditions can be applied. If the condition of step A1 is satisfied, the control proceeds to step A2. On the other hand, if the condition of step A1 is not satisfied, the control for this cycle ends.

[0035] In step A2, it is determined whether the accelerator opening detected by the accelerator opening sensor 8 is 0 (the accelerator is off). If this condition is satisfied, the process proceeds to step A3, and if not, the process proceeds to step A7. In step A3, it is determined whether the drive mode of the vehicle 1 is the sports mode. Here, if the drive mode is the sports mode, the control proceeds to step A4, and the first minimum rotational speed ω of the engine 2 is set according to the vehicle speed detected by the vehicle speed sensor 9. 1 is set. The first minimum rotational speed ω 1 is set in the normal mode (set in step A6 described later), and has a value higher than the second minimum rotational speed ω 2 . In the subsequent step A5, the operating state of the engine 2 is controlled so that the engine rotational speed becomes the first minimum rotational speed ω 1 , and the control for this cycle ends.

[0036] On the other hand, if the drive mode of the vehicle 1 is not the sports mode (is the normal mode) in step A3, the control proceeds to step A6, and the second minimum rotational speed ω of the engine 2 is set. The second minimum rotational speed ω 2 is set in the sports mode (set in step A4), and has a value lower than the first minimum rotational speed ω 2 . In the subsequent step A5, the operating state of the engine 2 is controlled so that the engine rotational speed becomes the second minimum rotational speed ω 1 , and the control for this cycle ends. 2 ​

[0037] In step A7 which proceeds when the accelerator opening is not 0 (the accelerator is on) in step A2, the driver demand output is set according to the accelerator opening detected by the accelerator opening sensor 8. The driver demand output is set based on characteristics as shown in, for example, FIG. 2. Also, in step A8, the target rotational speed ω of the engine 2 is set according to the driver demand output. Here, if the driver demand output is relatively large, the difference between the actual engine rotational speed and the target rotational speed ω at that time becomes large. Therefore, if the speed at which the engine rotational speed changes is too slow, the time until the actual engine rotational speed reaches the target rotational speed ω becomes long. On the other hand, in this embodiment, the speed will be changed according to the drive mode. TGT becomes set. Here, if the driver demand output is relatively large, the difference between the actual engine rotational speed at that time and the target rotational speed ω TGT becomes large. Therefore, if the speed at which the engine rotational speed changes is too slow, the time until the actual engine rotational speed reaches the target rotational speed ω TGT is reached becomes long. On the other hand, in this embodiment, the speed will be changed according to the drive mode.

[0038] In the subsequent step A9, it is determined whether the drive mode of the vehicle 1 is the sports mode. Here, if the drive mode is the sports mode, the control proceeds to step A10, and the first increase rate G 1 is set as the maximum increase rate of the engine rotational speed. The first increase rate G 1 has a value larger than the second increase rate G 2 set in the normal mode (set in step A12 described later). In the subsequent step A11, the operating state of the engine 2 is controlled so that the maximum increase rate of the engine rotational speed becomes the first increase rate G 1 , and the control in this cycle ends.

[0039] On the other hand, when the drive mode of the vehicle 1 is not the sports mode (when it is the normal mode) in step A9, the control proceeds to step A12, and the second increase rate G 2 is set as the maximum increase rate of the engine rotational speed. The second increase rate G 2 has a value smaller than the first increase rate G 1 set in the sports mode (set in step A10). In the subsequent step A11, the maximum increase rate of the engine rotational speed becomes the second increase rate G2 The operating state of the engine 2 is controlled to be as follows, and the control in this cycle ends.

[0040] [4. Operation] Figures 6(A) and (B) are graphs illustrating changes in the motor output with respect to the accelerator operation. (A) is the graph in the normal mode, and (B) is the graph in the sports mode. Before the time t when the accelerator pedal is not depressed 0 Prior to this, the first control is performed. In this first control, the first minimum rotational speed ω of the engine 2 in the sports mode 1 is set higher than the second minimum rotational speed ω of the engine 2 in the normal mode. 2 Therefore, the engine 2 before the time t in Fig. 6(A) rotates at the second minimum rotational speed ω 0 , and the engine 2 before the time t in Fig. 6(B) rotates at the first minimum rotational speed ω 2 . 0 1 1 Also, the output of the engine 2 before the time t is controlled to be substantially the same in the sports mode and the normal mode. In response to this, the generated power of the generator 4 and the output of the motor 3 are also controlled to be the same in the sports mode and the normal mode. Therefore, the output value A of the motor 3 before the time t in Fig. 6(A) is the same as the output value A of the motor 3 before the time t in Fig. 6(B), and the running state of the vehicle 1 is also the same.

[0041] When the accelerator pedal is depressed at the time t 0 , the second control is performed. At this time, as shown by the broken lines in Figs. 6(A) and (B), a large driver required output corresponding to the accelerator opening is set. For driving the motor 3 after the time t 0 , not only the generated power of the generator 4 but also the battery power stored in the battery 5 is used in combination. The motor output in the normal mode at the time t 0 0

[0042] At the time t 0 When the accelerator pedal is depressed, the second control is performed. At this time, as shown by the broken lines in Figs. 6(A) and (B), a large driver required output corresponding to the accelerator opening is set. For driving the motor 3 after the time t 0 , not only the generated power of the generator 4 but also the battery power stored in the battery 5 is used in combination. The motor output in the normal mode at the time t 0 in the normal mode at the time t0 It becomes the value obtained by summing the output value A corresponding to the generated power before and the output value B corresponding to the battery power. The battery power corresponds to the output value of the portion below the wavy line in FIGS. 6(A) and 6(B), and the generated power corresponds to the output value of the portion sandwiched between the wavy line and the solid line above it in FIGS. 6(A) and 6(B).

[0043] On the other hand, in the sports mode, since the first minimum rotational speed ω of the engine 2 is higher than that in the normal mode, it is possible to immediately increase the generated power by increasing the load on the generator 4 with respect to the engine 2. Therefore, at time t 1 the motor output in the sports mode at time t is the value obtained by summing the output value C, which is larger than the output value A, and the output value B. The output value C is an output of a magnitude corresponding to the generated power after the generator 4 has increased it. Thus, by controlling the engine rotational speed to be higher in advance by the first control, the motor output (the initial value of the output for accelerating the vehicle 1) at time t 0 can be easily increased. 0

[0044] Also, in the second control, the first increase rate G of the engine rotational speed in the sports mode 1 is set to be larger than the second increase rate G of the engine rotational speed in the normal mode 2 . As a result, the time taken for the engine rotational speed to rise to the target rotational speed ω TGT is shortened in the sports mode compared to the normal mode. Correspondingly, the time until the motor output reaches the driver required output is also shortened in the sports mode compared to the normal mode.

[0045] For example, in FIG. 6(A), the motor output reaches the driver required output at time t 1 , and in FIG. 6(B), the motor output reaches the driver required output at a time t 1 earlier than time t 2That is. The rising gradient of the motor output in the normal mode becomes gentle as shown by the solid line in Fig. 6(A) [as shown by the two-dot chain line in Fig. 6(B)]. On the other hand, the rising gradient of the motor output in the sports mode becomes steep as shown by the solid line in Fig. 6(B). These graphs show that the time from time t 0 until the driver required output is achieved in the sports mode is extremely short, indicating that a good acceleration response can be obtained.

[0046] [5. Effects] (1) The hybrid vehicle 1 of this embodiment is a hybrid vehicle that performs series running, and has a normal mode in which a driver required output corresponding to the accelerator opening is set, and a sports mode in which a driver required output greater than or equal to the size set in the normal mode according to the accelerator opening is set. Further, when performing series running, the above control device 10 controls the first minimum rotational speed ω 1 of the engine 2 in the sports mode to be higher than the second minimum rotational speed ω 2 of the engine 2 in the normal mode (first control).

[0047] That is, the minimum rotational speed (idle rotational speed) of the engine 2 in the sports mode is controlled to be higher than that in the normal mode. As a result, when the accelerator pedal is depressed, the engine rotational speed can be increased to a desired speed in a relatively short time. For example, as shown in Fig. 6(B), the output value C at time t 0 can be made larger than the output value A before time t 0 . Therefore, in series running in the sports mode, the acceleration response immediately after the accelerator is turned on can be improved.

[0048] (2) The above control device 10 controls the first increase rate G 1 to be larger than the second increase rate G 2 (second control). The first increase rate G 1is the maximum increase rate of the rotational speed of engine 2 in sports mode when in series driving and the driver demand output is not zero. Also, the second increase rate G 2 is the maximum increase rate of the rotational speed of engine 2 in normal mode when in series driving and the driver demand output is not zero.

[0049] In this way, by increasing the maximum increase rate of the engine rotational speed when the accelerator is on in sports mode, the generated power of generator 4 can be increased in a short time. For example, as shown in Fig. 6(B), the increase gradient of the generated power after time t 0 can be made steeper, and the motor output can be increased steeply. Therefore, the time until the motor output reaches the driver demand output can be shortened, and the acceleration response of vehicle 1 can be further improved.

[0050] (3) As shown in Fig. 4, the above control device 10 can set the first minimum rotational speed ω 1 according to the vehicle speed. By such a setting, the vehicle speed representing the running state of vehicle 1 can be reflected in the minimum rotational speed of engine 2, and the balance between the acceleration response and the quietness can be easily adjusted. Note that the relationship between the vehicle speed and the first minimum rotational speed ω 1 may be selected according to the driver's preference, for example, or may be automatically selected according to the running state of vehicle 1.

[0051] (4) Regarding the relationship between the vehicle speed and the first minimum rotational speed ω 1 , as shown by the solid line in Fig. 4, the lower the vehicle speed, the higher the first minimum rotational speed ω 1 may be set. By such a setting, the acceleration response from a stop state or a low-speed running state can be improved, and a more sporty running can be realized. However, since the noise and vibration of engine 2 in a stop state or a low-speed running state become slightly larger, the quietness may be slightly reduced.

[0052] (5) On the contrary, as shown by the two-dot chain line in Fig. 4, the higher the vehicle speed, the first minimum rotational speed ω1 It may be set high. With such a setting, the noise and vibration of the engine 2 in a stopped state or a low-speed running state are reduced, and a more comfortable and quieter driving can be realized. Also, the acceleration response in a high-speed running state can be improved. Regarding the acceleration response from a stopped state or a low-speed running state, it is advantageous to set characteristics as shown by the solid line in FIG. 4.

[0053] [6. Others] The above embodiments are merely illustrative, and there is no intention to exclude various modifications and applications of technologies not explicitly shown in this embodiment. Each configuration of this embodiment can be implemented with various modifications without departing from their gist. Also, each configuration of this embodiment can be selected as needed, or can be combined as appropriate.

[0054] For example, although the drive mode selector 7 is provided in the vehicle 1 described above, the drive mode selector 7 can be omitted, and either the normal mode or the sports mode may be automatically selected according to known conditions. Also, in the above embodiment, when series running in the sports mode, the control device 10 that performs the first control and the second control on the engine 2 was exemplified, but the second control can be omitted. At least in a hybrid vehicle that has at least a normal mode and a sports mode and performs series running, by performing the first control, the acceleration response immediately after the accelerator is turned on can be improved, and the same operational effects as those of the above-described embodiment can be obtained.

[0055] Also, in the above embodiment, the relationship between the vehicle speed and the first minimum rotational speed ω 1 as shown in FIG. 4 was exemplified, but the first minimum rotational speed ω 1 may be set as a fixed value, or parameters other than the vehicle speed may be reflected in the value of the first minimum rotational speed ω 1 . Also, the same applies to the second minimum rotational speed ω 2 , which may be set as a fixed value, or the vehicle speed and other parameters may be reflected in the value of the second minimum rotational speed ω 2 . At least, the first minimum rotational speed ω1 is set higher than the second lowest rotational speed ω 2 and by controlling the engine 2, the same operational effects as those of the above-described embodiment can be obtained.

Industrial Applicability

[0056] This case is applicable to the manufacturing industry of hybrid vehicles and is also applicable to the manufacturing industry of control devices for hybrid vehicles.

Explanation of Reference Numerals

[0057] 1 Vehicle (hybrid vehicle) 2 Engine 3 Motor 4 Generator 5 Battery 6 Clutch 7 Drive mode selector 8 Accelerator opening sensor 9 Vehicle speed sensor 10 Control device ω TGT Target rotational speed ω 1 First lowest rotational speed ω 2 Second lowest rotational speed G 1 First increase rate G 2 Second increase rate

Claims

1. A hybrid vehicle including an engine, a motor, a generator, and a control device for controlling at least the operating state of the engine, and performing series running in which the generator is caused to generate electricity by the driving force of the engine and the vehicle travels by the driving force of the motor, wherein the hybrid vehicle has a normal mode in which a driver required output corresponding to an accelerator opening is set, and a sports mode in which the driver required output greater than or equal to the size set in the normal mode is set according to the accelerator opening, and the control device, when performing the series running, makes a first minimum rotation speed of the engine in the sports mode higher than a second minimum rotation speed of the engine in the normal mode, and makes the output of the engine and the generated power of the generator in a state where the accelerator is off the same between the sports mode and the normal mode A hybrid vehicle characterized by the above.

2. In a situation where the series running is in progress and the driver required output is not zero, after defining a maximum increase rate of the rotation speed of the engine in the sports mode as a first increase rate and a maximum increase rate of the rotation speed of the engine in the normal mode as a second increase rate, the control device makes the first increase rate greater than the second increase rate A hybrid vehicle according to claim 1, characterized by the above.

3. The control device sets the first minimum rotation speed according to the vehicle speed A hybrid vehicle according to claim 1 or 2, characterized by the above.

4. The control device increases the first minimum rotation speed as the vehicle speed is lower A hybrid vehicle according to claim 3, characterized by the above.

5. The control device increases the first minimum rotation speed as the vehicle speed is higher A hybrid vehicle according to claim 3, characterized by the above.

6. The control device controls the engine and the generator so that the first minimum rotation speed is higher than the second minimum rotation speed while maintaining the output of the engine and the generated power of the generator in a state where the accelerator is off by adjusting the load of the generator on the engine A hybrid vehicle according to any one of claims 1 to 5, characterized by the above.

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