Control device for vehicle

Abstract

The present invention is a control device (5) for a vehicle that is equipped with: a battery (6); a path which extends from a motor (3) to an output shaft (12); a path which is different from the aforementioned path and extends from an engine (2) to the output shaft (12); a path which extends from the engine (2) to a generator (4); a path which extends from the generator (4) to the output shaft (12); and a motor clutch (20). The vehicle is configured to be capable of executing regenerative motor assistance and regenerative generator assistance in a first state in which power can be transmitted between the engine (2) and the output shaft (12). The control device (5) comprises: a calculation unit (5A) that calculates requested torque for the vehicle; and a control unit (5B) that, when a first requested torque, which is the requested torque calculated in the first state and in a released state of the motor clutch (20), falls below a prescribed minimum torque, executes regenerative generator assistance regardless of whether or not regenerative motor assistance is executed.

Description

Vehicle control device

[0001] The present invention relates to a control device for a vehicle equipped with an engine, a motor, and a generator.

[0002] Conventionally, vehicles equipped with an engine, a motor, and a generator (hybrid vehicles or plug-in hybrid vehicles capable of external charging or external power supply) that can run while switching between driving modes have been put into practical use. The driving modes include an EV mode in which the vehicle runs solely on the motor using charged power from the drive battery, a series mode in which the engine drives the generator to generate electricity and the vehicle runs solely on the motor, and a parallel mode in which the vehicle runs primarily on the engine with assistance from the motor when necessary.

[0003] For example, Patent Document 1 discloses a control device for a hybrid vehicle capable of separately outputting engine power and motor power, which starts engaging the motor clutch when motor assist is required while the vehicle is running in parallel mode with the motor clutch disengaged. When the motor clutch transitions from a disengaged state to an engaged state, this control device operates the generator to power the vehicle to compensate for the driving force until the motor clutch is fully engaged.

[0004] International Publication No. 2020 / 148973

[0005] The above-mentioned Patent Document 1 aims to improve the response delay when the motor clutch is engaged when the required driving force increases while the engine is running (i.e., during power running), but does not mention what happens when the required driving force decreases. Therefore, there is room for improvement in how the generator is used when the required driving force (also called required torque or required output) decreases.

[0006] The vehicle control device of the present invention was devised in consideration of these problems, and one of its objectives is to improve power consumption by devising ways to utilize the generator when the required torque decreases. However, this objective is not limited to this, and another objective of the present invention is to achieve effects that cannot be obtained by conventional techniques, which are derived from the configurations shown in the below-described embodiments of the invention.

[0007] The disclosed vehicle control device can be realized as the following disclosed aspects (application examples) and solves at least part of the above-mentioned problems. Each of the aspects from aspect 2 onwards is an aspect that can be selected as an additional aspect, and each of the aspects from aspect 2 onwards is an aspect that can be omitted. None of the aspects from aspect 2 onwards is disclosed as an aspect or configuration that is essential to the present invention.

[0008] Aspect 1. The disclosed vehicle control device includes a drive battery, a first power transmission path from a motor to an output shaft on a drive wheel side, a second power transmission path separate from the first power transmission path and extending from an engine to the output shaft, a third power transmission path from the engine to a generator, a fourth power transmission path from the generator to the output shaft, and a motor clutch provided on the first power transmission path for connecting and disconnecting power transmission. The vehicle is configured to execute a regenerative motor assist that transmits regenerative torque of the motor to the output shaft in a first state in which power transmission is possible between the engine and the output shaft, and a regenerative generator assist that transmits regenerative torque of the generator to the output shaft in the first state, excluding power generation torque generated by the generator generating electricity when the engine is operated at a speed equivalent to the best fuel economy point. The control device includes a calculation unit that calculates the required torque of the vehicle, and a control unit that performs the regenerative generator assist regardless of whether the regenerative motor assist is performed when the required torque calculated by the calculation unit in the first state and when the motor clutch is open falls below the minimum torque of the engine.

[0009] Aspect 2. In the above aspect 1, it is preferable that the control unit executes the regenerative generator assist without executing the regenerative motor assist when the first required torque is smaller than the minimum torque and equal to or greater than a lower limit threshold torque obtained by subtracting a predetermined value from the minimum torque, and executes the regenerative generator assist and then the regenerative motor assist when the first required torque is smaller than the lower limit threshold torque.

[0010] Aspect 3. In the above-described aspect 1 or 2, it is preferable that the control device further sets a regenerative torque range having a predetermined margin above and / or below the minimum torque. In this case, it is preferable that the control unit executes the regenerative generator assist and then the regenerative motor assist if the first required torque is smaller than a lower limit value of the regenerative torque range.

[0011] Aspect 4. In the above-described aspect 2 or 3, when the regenerative motor assist is performed, the control unit preferably synchronizes the rotation speed of the motor with the rotation speed of the output shaft side, and then engages the motor clutch that is in a released state.

[0012] Aspect 5. In any one of Aspects 1 to 4 above, it is preferable that the vehicle be configured to be able to execute a powering motor assist in the first state, which transmits the powering torque of the motor to the output shaft, and a powering generator assist in the first state, which transmits the powering torque of the generator to the output shaft. In this case, it is preferable that the control unit executes the powering generator assist without executing the powering motor assist when the first required torque is greater than a predetermined reference torque and is equal to or less than an upper threshold torque obtained by adding a second predetermined value to the reference torque, and executes the powering motor assist after executing the powering generator assist when the first required torque is greater than the upper threshold torque.

[0013] According to the disclosed vehicle control device, it is possible to improve electricity efficiency by making better use of the generator when the required torque decreases.

[0014] 1 is a diagram showing a vehicle equipped with a control device according to an embodiment; FIG. 2 is a left side view showing a powertrain mounted on the vehicle of FIG. 1; FIG. 3 is a diagram showing a skeleton diagram illustrating the powertrain of FIG. 2 together with the control device of FIG. 1; FIG. 4 is a diagram illustrating processing blocks performed by the control device of FIG. 1; FIG. 5 is a diagram for explaining thresholds set in the control device of FIG. 1; FIG. 6 is a diagram showing changes in clutch state, drive torque, and battery power when transitioning from parallel mode to series mode in powering side assist control; FIG. 7 is an example flowchart performed by the control device of FIG. 1, mainly showing powering side assist control; and FIG. 8 is an example flowchart performed by the control device of FIG. 1, mainly showing regeneration side assist control. 1 is a graph illustrating the operation of powering-side assist control during acceleration, where (A) is vehicle speed, (B) is accelerator opening, (C) is driving mode, (D) is required drive shaft torque, (E) is motor clutch release request, (F) is motor clutch release state, (G) is generator output ratio, (H) is generator assist operation state, (I) is motor rotation synchronous power, (J) is actual battery power, (K) is engine required torque, (L) is motor required torque, and (M) is generator required torque. 1 is a graph illustrating the operation of regeneration side assist control during deceleration, where (A) is vehicle speed, (B) is accelerator opening, (C) is driving mode, (D) is required drive shaft torque, (E) is motor clutch release request, (F) is motor clutch release state, (G) is generator output ratio, (H) is generator assist operation state, (I) is motor rotation synchronous power, (J) is actual battery power, (K) is engine required torque, (L) is motor required torque, and (M) is generator required torque.

[0015] A vehicle control device according to an embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and is not intended to exclude various modifications or applications of techniques not explicitly described in the embodiment. The configurations of the present embodiment can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected or combined as needed.

[0016] [1. Overall Configuration] The control device 5 of this embodiment is applied to a vehicle 1 shown in Fig. 1. This vehicle 1 is a hybrid vehicle equipped with an engine 2, a motor 3, and a generator 4 as drive sources. The generator 4 is connected to the engine 2 and can operate independently of the operating state of the motor 3. The vehicle 1 is equipped with a drive battery 6, which is the power source for the motor 3, and a transaxle 10.

[0017] The vehicle 1 is also provided with three driving modes: EV mode, series mode, and parallel mode. These driving modes are alternatively selected by the control device 5 according to the vehicle state, driving state, driver required output, etc., and the engine 2, motor 3, and generator 4 are used appropriately according to the selected mode. The motor 3 may have a power generation function (generator function), and the generator 4 may have an electric driving function (motor function).

[0018] The EV mode is a driving mode in which the engine 2 and generator 4 are stopped and the vehicle 1 is driven only by the motor 3 using the charged power of the drive battery 6. The EV mode is selected when the driving load and driving speed are low or when the charge level of the battery 6 is high. The series mode is a driving mode in which the engine 2 drives the generator 4 to generate electricity and the generated electricity is used to drive the vehicle 1 by the motor 3. The series mode is selected when the driving load is high or when the charge level of the battery 6 is low. The parallel mode is a driving mode in which the vehicle 1 is driven mainly by the engine 2 and the motor 3 assists in driving and braking the vehicle 1 as needed, and is selected when the driving speed is high.

[0019] The engine 2 and the motor 3 are connected in parallel to the drive wheels 8 via a transaxle 10, and the power of the engine 2 and the motor 3 is transmitted separately. The generator 4 and the drive wheels 8 are also connected in parallel to the engine 2 via the transaxle 10, and the power of the engine 2 is transmitted to the generator 4 as well as to the drive wheels 8.

[0020] The transaxle 10 is a power transmission device that integrates a final drive (final reduction gear) including a differential gear 18 (hereinafter referred to as "diff 18") and a transmission (reduction gear), and incorporates multiple mechanisms that transmit power between a driving source and a driven device. The transaxle 10 of this embodiment is configured to be switchable between high and low gears (switching between high and low gears), and when switching to parallel mode, the control device 5 selects either a high gear or a low gear depending on the driving conditions, required output, etc.

[0021] The engine 2 is an internal combustion engine (gasoline engine, diesel engine) that uses gasoline or diesel as fuel. The engine 2 is a so-called transversely mounted engine that is arranged sideways so that the orientation of the crankshaft 2a (rotating shaft) coincides with the width direction of the vehicle 1, and is fixed to the right side of the transaxle 10. The crankshaft 2a is arranged parallel to the drive shaft 9 of the drive wheels 8. The operating state of the engine 2 may be controlled by the control device 5 or by an engine control device (not shown).

[0022] Both the motor 3 and the generator 4 are motor generators that function as both an electric motor and a generator. The motor 3 is a drive source that exchanges power with the battery 6, primarily functioning as an electric motor to drive the vehicle 1 and as a generator during regeneration. The generator 4 functions as an electric motor (starter) when starting the engine 2, and when the engine 2 is running, is driven by engine power to generate electricity and supply power to the battery 6. Inverters (not shown) that convert DC current to AC current are provided around (or inside) each of the motor 3 and the generator 4. The rotation speeds of the motor 3 and the generator 4 are controlled by controlling the inverters. The operating states of the motor 3, the generator 4, and each inverter may be controlled by the control device 5, or by a motor control device or a generator control device (not shown).

[0023] The battery 6 is a secondary battery such as a lithium-ion secondary battery or a nickel-metal hydride battery. In this embodiment, a short-term SOP (maximum short-term dischargeable power, short-term State Of Power) and a long-term SOP (maximum long-term dischargeable power, long-term State Of Power) are set as the maximum value of dischargeable power [kW] for the battery 6. The short-term SOP is the maximum power applied when the discharge time is equal to or shorter than a predetermined time (a relatively short time). The scale (length of time) for which the short-term SOP is applied is assumed to be, for example, several seconds. On the other hand, the long-term SOP is the maximum power applied when the discharge time exceeds a predetermined time, and is set to a smaller value than the short-term SOP. The long-term SOP is a parameter that can correspond to, for example, the rated output power of a typical battery 6.

[0024] The values ​​of the short-term SOP and long-term SOP may be preset fixed values, or may be variable values ​​that are set depending on the operating state of the battery 6 (such as the state of charge SOC, state of health SOH, discharge current value, battery voltage, and battery temperature) and the running state of the vehicle 1 (such as the running mode, vehicle speed, outside air temperature, and accelerator opening).The same applies to the predetermined time period during which the short-term SOP can be used; it may be a preset fixed value, or may be a variable value that is set depending on the operating state of the battery 6 and the running state of the vehicle 1.

[0025] The vehicle 1 is configured to be able to execute a power running motor assist in which the power running torque of the motor 3 is transmitted to the output shaft 12 and a power running generator assist in which the power running torque of the generator 4 is transmitted to the output shaft 12 in a first state in which power can be transmitted between the engine 2 and the output shaft 12 (see FIG. 2 ) on the drive wheel 8 side. The first state includes a parallel mode and a mode in which the engine clutch 30 (see FIG. 3 ) is released (hereinafter referred to as the "ENG clutch release mode"). The ENG clutch release mode is a driving mode that is implemented when transitioning from the parallel mode to the EV mode or the series mode, and will be described in detail later. The power running motor assist and the power running generator assist can be executed independently or temporarily used together.

[0026] Furthermore, in the first state, the vehicle 1 of this embodiment is configured to be able to perform regenerative motor assist, which transmits the regenerative torque of the motor 3 to the output shaft 12. Furthermore, in the first state, the vehicle 1 of this embodiment is configured to be able to perform regenerative generator assist, which transmits the regenerative torque of the generator 4 (regenerative generator torque) excluding a predetermined power generation torque, to the output shaft 12. The regenerative motor assist and the regenerative generator assist can be performed independently or temporarily used together.

[0027] The power generation torque referred to here refers to the torque generated by the generator 4 generating power when the engine 2 is operated at a torque greater than the torque required by the vehicle 1. In the vehicle 1 of this embodiment, in the first state, when the torque required by the vehicle 1 is smaller than the engine torque (for example, the output torque when the engine 2 is operated near the best fuel economy point), the engine 2 is operated, for example, at the operating point with the best fuel economy (the best fuel economy point), and an excess torque relative to the torque required by the vehicle 1, which will be described later, is transmitted to the generator 4 to generate power. Alternatively, when the torque required by the vehicle 1 is greater than the engine torque, the torque that is insufficient with the torque of the engine 2 is compensated for by the torque of the motor 3 and the generator 4. This control will be described in detail in the explanation of the operation.

[0028] The vehicle 1 is provided with a vehicle speed sensor 42 that detects the vehicle speed and a shift position sensor 43 that detects the shift position. The vehicle speed sensor 42 is an example of a vehicle speed detection unit that detects the vehicle speed. The vehicle 1 of this embodiment is also provided with a motor rotation speed sensor 44 that detects the rotation speed of the motor 3, an output shaft rotation speed sensor 45 that detects the rotation speed of the output shaft 12, a voltage sensor 46 that detects the voltage of the battery 6, a current sensor 47 that detects the input / output current of the battery 6, and an accelerator opening sensor 48 that detects the amount of depression of the accelerator pedal (accelerator opening) and the depression speed (accelerator opening speed). Information detected by each of the sensors 42 to 48 is transmitted to the control device 5.

[0029] The control device 5 is an electronic control device configured as, for example, an LSI device or an embedded electronic device that integrates a microprocessor, ROM, RAM, etc., and performs integrated control of various devices mounted on the vehicle 1. The control device 5 of this embodiment selects a driving mode according to the driver's required output, etc., and controls various devices (e.g., the engine 2 and the motor 3) according to the selected driving mode, as well as controlling the engagement and disengagement states of the motor clutch 20 (see FIG. 3 ) and the engine clutch 30 in the transaxle 10.

[0030] [2. Transaxle] Figure 2 is a side view of the powertrain 7, including the engine 2, motor 3, generator 4, and transaxle 10, as seen from the left side. Note that the engine 2 is omitted from this side view. Figure 3 is a skeleton diagram of the powertrain 7 equipped with the transaxle 10 of this embodiment. As shown in Figures 2 and 3, the transaxle 10 is provided with six shafts 11 to 16 arranged parallel to one another. Hereinafter, the rotating shaft connected coaxially with the crankshaft 2a will be referred to as the input shaft 11.

[0031] Similarly, the rotating shafts connected coaxially to the drive shaft 9, the rotating shaft 3a of the motor 3, and the rotating shaft 4a of the generator 4 are called the output shaft 12, the motor shaft 13, and the generator shaft 14. Furthermore, the rotating shaft arranged on the power transmission path between the input shaft 11 and the output shaft 12 is called the first countershaft 15, and the rotating shaft arranged on the power transmission path between the motor shaft 13 and the output shaft 12 is called the second countershaft 16.

[0032] Both ends of each of the six shafts 11 to 16 are supported by a casing 10C of the transaxle 10 via bearings (not shown). Openings are formed in the side surfaces of the casing 10C located on the input shaft 11, output shaft 12, motor shaft 13, and generator shaft 14, and the shafts are connected to the crankshaft 2a and other components through these openings.

[0033] Four power transmission paths are formed inside the transaxle 10. Specifically, as shown by the two-dot chain line or the dashed line in Figure 2, these four paths are: a first power transmission path 51 from the motor 3 to the output shaft 12, a second power transmission path 52 from the engine 2 to the output shaft 12, a third power transmission path 53 from the engine 2 to the generator 4, and a fourth power transmission path 54 from the generator 4 to the output shaft 12. Hereinafter, these four power transmission paths 51 to 54 will be abbreviated as the first path 51, the second path 52, the third path 53, and the fourth path 54, respectively.

[0034] The first path 51 and the second path 52 are both drive power transmission paths and are provided as separate (mutually independent) paths. The first path 51 is a path related to power transmission from the motor 3 to the output shaft 12 on the drive wheel 8 side, and is responsible for transmitting power when the motor 3 is operating. A motor clutch 20 (see FIG. 3 ) that connects and disconnects the power transmission is provided on the first path 51. The motor clutch 20 is configured, for example, by a sleeve clutch, a multi-plate clutch, or a planetary gear mechanism including a clutch and a brake.

[0035] The second path 52 is a path for transmitting power from the engine 2 to the output shaft 12 on the drive wheel 8 side, and is responsible for transmitting power when the engine 2 is operating. An engine clutch 30 (see FIG. 3 ) that connects and disconnects the power transmission is provided on the second path 52. The engine clutch 30 is configured, for example, by a sleeve-type clutch, a multi-plate clutch, or a planetary gear mechanism including a clutch and a brake. Note that the engine clutch 30 of this embodiment has a high / low switching function that allows switching between a high gear and a low gear.

[0036] The third path 53 is a power transmission path for power generation. Specifically, the third path 53 is a path for transmitting power from the engine 2 to the generator 4 via the input shaft 11 and the generator shaft 14, and is responsible for transmitting power when the engine 2 starts and when the engine 2 generates power. The fourth path 54 is a path that combines the first path 51 and the third path 53 (paths that overlap with these), and constitutes a drive power transmission path.

[0037] Next, the configuration of the transaxle 10 of this embodiment will be briefly described using Figure 3. Note that the configuration of the transaxle 10 described here is merely an example. In the following description, a "fixed gear" refers to a gear that is integral with a shaft and cannot rotate relative to the shaft. Additionally, an "idling gear" refers to a gear that is pivotally supported so as to be rotatable relative to the shaft.

[0038] Two fixed gears 11H, 11L are provided on the input shaft 11. The two fixed gears 11H, 11L have different numbers of teeth and are constantly meshed with two idling gears 15H, 15L, each having a different number of teeth, that are provided on the first counter shaft 15. In this embodiment, the fixed gear 11L, which has fewer teeth, meshes with the idling gear 15L, which has a larger number of teeth, to form a low gear, and the other fixed gear 11H, which has more teeth, meshes with the other idling gear 15H, which has a smaller number of teeth, to form a high gear.

[0039] The idling gear 15H has a toothed surface on its left side that meshes with the fixed gear 11H, and a dog gear 15d that is coupled to a contact portion that protrudes from the right side of the toothed surface. The idling gear 15L has a toothed surface on its right side that meshes with the fixed gear 11L, and a dog gear 15e that is coupled to a contact portion that protrudes from the left side of the toothed surface. Dog teeth (not shown) are provided at the tip (radially outer end) of each of the dog gears 15d, 15e.

[0040] The engine clutch 30 is disposed between the two idling gears 15H, 15L and controls the connection and disconnection of power from the engine 2 and switches between a high gear and a low gear. The high gear and the low gear are examples of multi-stage gears provided on the second path 52. The engine clutch 30 of this embodiment includes a hub 31 fixed to the first countershaft 15 and an annular sleeve 32 coupled to the first countershaft 15 so as to be non-rotatable relative to the hub 31 (first countershaft 15) and slidable in the axial direction of the first countershaft 15. The sleeve 32 moves left and right from a neutral position in the drawing when an actuator (not shown) is controlled by the control device 5. Spline teeth (not shown) are provided on the radially inner side of the sleeve 32. The spline teeth engage with the dog teeth of the dog gears 15d, 15e, thereby engaging the sleeve 32 with the dog gear 15d or the dog gear 15e. When the sleeve 32 is in the neutral position, both of the two idling gears 15H, 15L are in an idling state. In this case, even if the engine 2 is operating, the power of the engine 2 (the rotation of the input shaft 11) is not transmitted to the output shaft 12, and the power transmission of the engine 2 is interrupted.

[0041] When the sleeve 32 moves to either the left or right from the neutral position and engages with the dog gear 15d, 15e of one of the two idler gears 15H, 15L, the rotation of the input shaft 11 is transmitted to one of the idler gears 15H, 15L. Hereinafter, this state will be referred to as the rotationally coupled state. In the transaxle 10 of this embodiment, the sleeve 32 moves to the right and engages with the dog gear 15e of the idler gear 15L, thereby rotationally coupling the idler gear 15L of the low gear to the first countershaft 15. Conversely, when the sleeve 32 moves to the left and engages with the dog gear 15d of the idler gear 15H, the idler gear 15H of the high gear is rotationally coupled to the first countershaft 15. The engine clutch 30 is an example of an engine-side connection / disconnection mechanism and also an example of a selection mechanism that couples one of the multi-speed gears (high gear and low gear) to the power transmission path.

[0042] Furthermore, in the transaxle 10 of this embodiment, when the sleeve 32 moves, the generator 4 synchronizes the rotational speed of the input shaft 11 (i.e., the rotational speed of the idler gears 15H, 15L) to match the rotational speed of the drive wheels 8. In other words, when the sleeve 32 is engaged with the dog gears 15d, 15e of either the idler gears 15H, 15L (when selecting a high gear or a low gear, or when switching between a high gear and a low gear), prior to the engagement, the control device 5 controls the inverter on the generator 4 side so that the rotational speed of the input shaft 11 matches the rotational speed of the first counter shaft 15.

[0043] The low-side fixed gear 11L is also constantly meshed with a fixed gear 14a provided on the generator shaft 14. In other words, the input shaft 11 and the generator shaft 14 are connected via the two fixed gears 11L, 14a, allowing power to be transmitted between the engine 2 and the generator 4. In addition, a fixed gear 15a is provided on the first counter shaft 15 adjacent to the right side of the low-side idling gear 15L. This fixed gear 15a is constantly meshed with a ring gear 18a of a differential 18 provided on the output shaft 12.

[0044] Two fixed gears 16a, 16b are provided on the second countershaft 16. The right fixed gear 16a is constantly meshed with an idler gear 13b provided on the motor shaft 13, and the left fixed gear 16b is constantly meshed with a ring gear 18a of a differential 18. The idler gear 13b of the motor shaft 13, together with a clutch portion 21 interposed on the motor shaft 13, constitutes a motor clutch 20.

[0045] The clutch unit 21 is a multi-plate clutch that controls the connection / disconnection state of the power of the motor 3, and has a first engagement element 22 fixed to the motor shaft 13 and a second engagement element 23 fixed to the idling gear 13b. When the motor 3 is powered, the first engagement element 22 receives power from the motor 3, and the second engagement element 23 outputs power to the drive wheels 8. These engagement elements 22, 23 are driven in directions to move away from each other (disconnected, released) or towards each other (engaged, connected) depending on the oil pressure of the oil that flows in from an oil passage inlet provided in the motor shaft 13, for example.

[0046] When the motor clutch 20 is engaged, the power of the motor 3 is transmitted to the drive wheels 8 via the idling gear 13b and the fixed gears 16a, 16b, and the rotation of the drive wheels 8 is transmitted to the motor 3. In other words, when the motor clutch 20 is engaged, power driving and regenerative braking by the motor 3 are possible. Conversely, when the motor clutch 20 is released (disconnected) while the vehicle is running on the engine 2 (when the motor 3 is stopped), the idling gear 13b rotates freely and the rotation of the drive wheels 8 is not transmitted to the motor 3, so the motor 3 is not rotated together and resistance is reduced. The motor clutch 20 of this embodiment is basically switched between an engaged state and a disengaged state by, for example, hydraulic control, in accordance with the operation and non-operation of the motor 3.

[0047] Note that a pressure regulating device made up of a plurality of solenoid valves (on-off solenoid valves, linear solenoid valves, etc.) may be provided on the hydraulic circuit, and the oil pumped from a pump (not shown) may be adjusted to an appropriate hydraulic pressure to control the engagement and disengagement of the motor clutch 20. Alternatively, the motor clutch 20 may be provided with an electronically controlled coupling instead of the pump and the multi-plate clutch unit 21, and the engagement and disengagement of the power transmission may be controlled by the control device 5.

[0048] [3. Control Overview] In the first state, when the required torque when the motor clutch 20 is disengaged (first required torque, described later) falls below a predetermined threshold (minimum torque, described later), the control device 5 described above performs regenerative generator assist regardless of whether or not regenerative motor assist is performed. That is, in the first state, the control device 5 first performs control to compensate for the braking torque (regenerative torque) that may be insufficient with the engine 2 alone, with the regenerative torque of the generator 4. Hereinafter, this control will be referred to as "regenerative side assist control."

[0049] The control device 5 of this embodiment performs similar control on the powering side in addition to the regenerative side. Specifically, in the first state, when the required torque when the motor clutch 20 is disengaged (first required torque) exceeds a threshold value (reference torque described later) different from that on the regenerative side, the control device 5 performs powering generator assist regardless of whether powering motor assist is performed. That is, in the first state, the control device 5 performs control to first compensate for the driving torque (powering torque) that may be insufficient with the engine 2 alone, with the powering torque of the generator 4. Hereinafter, this control will be referred to as "powering side assist control."

[0050] Both the powering side assist control and the regeneration side assist control can be started when the driving mode is in the first state (parallel mode or ENG clutch release mode in this embodiment) and the motor clutch 20 is released. In each assist control, generator assist is executed first, but if the shortage can be covered by generator assist alone, motor assist is not started and the control is completed by generator assist alone. On the other hand, if the shortage cannot be covered by generator assist alone, the generator assist takes over (passes the baton) to motor assist, and after motor assist starts, generator assist ends.

[0051] Furthermore, the control device 5 of this embodiment performs a driving mode selection control in addition to the above two assist controls. The driving mode selection control selects and sets an optimal driving mode from EV mode, series mode, and parallel mode based on information about the vehicle 1 (e.g., vehicle speed, accelerator opening, required torque, charging power of the battery 6, etc.). This selection control can employ a conventional method.

[0052] Furthermore, in the two assist controls described above, the control device 5 can control the connection / disconnection state of the motor clutch 20 (hereinafter referred to as "motor connection / disconnection control") and the connection / disconnection state of the engine clutch 30 (hereinafter referred to as "engine connection / disconnection control"). Note that the motor connection / disconnection control and the engine connection / disconnection control are also performed when each assist control is not being performed.

[0053] Motor connection / disconnection control is performed, for example, in the following cases: When switching from parallel mode to EV mode or series mode When powering motor assist or regenerative motor assist is required during parallel mode When powering motor assist or regenerative motor assist ends and assistance is no longer required During motor connection / disconnection control, if the motor clutch 20 in the open state is to be engaged, rotation synchronization control of the motor 3 is performed prior to the engagement.

[0054] The engine connection / disconnection control is performed, for example, in the following cases: When switching from EV mode or series mode to parallel mode When switching from parallel mode to EV mode or series mode When the vehicle 1 accelerates and reaches a vehicle speed equal to or greater than a first vehicle speed threshold V1 When the vehicle 1 decelerates and reaches a vehicle speed below the first vehicle speed threshold V1 The first vehicle speed threshold V1 is a threshold at which the engine clutch 30 is switched between connection and disconnection, and may be a fixed value or a variable value set in the control device 5. Furthermore, the first vehicle speed threshold V1 does not need to be the same during acceleration and deceleration, and hysteresis may be provided to prevent adverse effects of switching.

[0055] [4. Control Configuration] The control device 5 is provided with a calculation unit 5A and a control unit 5B as elements for performing at least regeneration-side assist control. These elements represent some of the functions of a program executed by the control device 5 and are realized by software. However, some or all of the functions may be realized by hardware (electronic circuits), or may be realized by a combination of software and hardware.

[0056] In the control device 5 of this embodiment, in addition to the regeneration side assist control, powering side assist control, driving mode selection control, motor connection / disconnection control, and engine connection / disconnection control are also performed. These controls may be performed by the control unit 5B described above, or may be performed by functional elements other than the control unit 5B (for example, the regeneration side control unit, the selection control unit, the motor connection / disconnection control unit, and the engine connection / disconnection control unit). In the following explanation, an example is given in which the control unit 5B performs all of the controls. Below, the powering side assist control will be explained first, and then the regeneration side assist control will be explained.

[0057] [4-1. Powering-Side Assist Control] The calculation unit 5A calculates the required torque (also referred to as required output or required driving force) of the vehicle 1. The calculation unit 5A calculates the required torque based on, for example, information related to accelerator operation (accelerator opening degree and accelerator opening speed), and transmits the calculated value to the control unit 5B. Note that the calculation unit 5A may calculate the required torque by taking into account the vehicle speed in addition to the information related to accelerator operation. Furthermore, the calculation unit 5A constantly calculates the required torque (e.g., at a predetermined calculation cycle) as long as the main power supply of the vehicle 1 is on (Ready ON). In the following description, the required torque calculated by the calculation unit 5A when the driving mode is in the first state and the motor clutch 20 is in a disengaged state (when power transmission between the motor 3 and the output shaft 12 is interrupted) is specifically referred to as the "first required torque."

[0058] The required torque may include a driver required torque that the driver requests of the vehicle 1 and a required drive shaft torque that is a limited value that can be output by the vehicle 1. As shown in Fig. 4, the calculation unit 5A of this embodiment calculates the driver required torque based on at least the accelerator operation, preferably also taking into consideration the vehicle speed (step A1). Furthermore, the calculation unit 5A calculates the limited value as the required drive shaft torque if it is necessary to limit the driver required torque, or calculates the value as is if it is not necessary to limit it (step A2). In the following control, the required drive shaft torque is used as the required torque (first required torque).

[0059] When the first required torque exceeds a predetermined reference torque, the control unit 5B performs power-running generator assist regardless of whether power-running motor assist is performed. The reference torque here is a threshold value used to determine whether power-running generator assist is required, and may be referred to as an assist reference torque. The reference torque is set based on the maximum torque of the engine 2. The reference torque may be stored in advance in the control unit 5, or the control unit 5 may be provided with a functional element (e.g., a setting unit) for setting the reference torque.

[0060] The reference torque may be set, for example, taking into consideration that using powering generator assist in addition to the torque of the engine 2 is more efficient for the vehicle 1 as a whole than providing the required torque solely with the torque of the engine 2. The reference torque may also be set, for example, to a torque value equal to or slightly lower than the maximum torque of the engine 2, or may be set based on the maximum torque and vehicle speed of the engine 2. For example, in the high vehicle speed range where the rotation speed of the engine 2 is high, the engine load increases and efficiency tends to deteriorate, so in consideration of this tendency, the reference torque may be set to a value lower than the maximum torque of the engine 2 in the high vehicle speed range.

[0061] 4, in the control device 5 of this embodiment, the control unit 5B determines whether the driving mode is in the first state (step B1), and further determines whether the motor clutch 20 is in the disengaged state (step B2), and if both determinations are true, permits generator assist (step B3). Then, the required drive shaft torque when the determinations of steps B1 and B2 are both true is obtained as the first required torque, and it is determined whether the first required torque exceeds the reference torque, and if this is true, calculates the powering assist torque (step B4).

[0062] The powering assist torque calculated here is a torque deficiency that corresponds to the difference between the first required torque and the torque of the engine 2 (engine required torque). Therefore, the calculation of the powering assist torque in step B4 uses the result of the calculation of the engine required torque (step B5). Furthermore, the calculation of the engine required torque in step B5 uses the result of the calculation of the required drive shaft torque (step A2) and the result of the calculation of the power generation torque (step B6).

[0063] If the powering assist torque is calculated in step B4, the powering generator torque (generator required torque) to be realized by the powering generator assist is calculated based on this powering assist torque (step B7). Note that in the regeneration-side assist control described below, the result of the calculation of the power generation torque (step B6) is used in the calculation of the regeneration generator torque (generator required torque), but this is not used in the powering-side assist control. Furthermore, when powering generator assist is handed over to powering motor assist, the powering motor torque (motor required torque) is also calculated (step B8), and the connection / disconnection state of the motor clutch 20 is controlled (step B9).

[0064] In this embodiment, the control unit 5B performs the above steps B1 to B9, but the control device 5 may also be provided with functional elements (e.g., a judgment unit) that make judgments in steps B1 and B2, functional elements (e.g., a permission unit) that give permission in step B3, and functional elements (e.g., a calculation unit) that perform calculations in steps B4 to B8.

[0065] If the first required torque is greater than the reference torque and is equal to or less than an upper threshold torque obtained by adding a predetermined value (second predetermined value) to the reference torque, the control unit 5B performs power generation assist without performing power motor assist. In other words, if the first required torque exceeds the reference torque within a certain predetermined range (hereinafter referred to as the "predetermined range on the power running side") (if the reference torque < first required torque ≦ upper threshold torque), only power generator assist is performed, and power motor assist is not performed. In this case, in step B7, the power assist torque calculated in step B4 may be calculated as the power generator torque.

[0066] Furthermore, when the first required torque is greater than the upper threshold torque, the control unit 5B performs powering generator assist and then powering motor assist. In other words, when the first required torque exceeds the reference torque by more than a predetermined range on the powering side (when the upper threshold torque<the first required torque), both powering generator assist and powering motor assist are performed. In this way, powering motor assist is not performed unless the first required torque exceeds the reference torque by more than a predetermined value, so the motor clutch 20 is maintained in an open state for a longer period of time.

[0067] In this case, for example, the maximum powering generator torque that can be output by the generator 4 may be calculated in step B7, and the torque that cannot compensate for the first required torque with the powering generator torque may be calculated as the powering motor torque in step B8. Furthermore, after the powering generator assist is handed over to the powering motor assist, the powering assist torque calculated in step B4 may be calculated as the powering motor torque in step B8.

[0068] 5, the control device 5 may set a powering torque range Rp having a predetermined margin Mp above and / or below the reference torque. In this case, if the first required torque is greater than the upper limit of the powering torque range Rp, the control unit 5B preferably performs powering generator assist and then powering motor assist. Furthermore, if the first required torque is greater than the reference torque and equal to or less than the upper limit of the powering torque range Rp, the control unit 5B preferably performs only powering generator assist.

[0069] 5 is a graph showing the relationship between torque and vehicle speed, and may be stored as a map in the control device 5. The graph of maximum torque of engine 2 in FIG. 5 shows the maximum positive torque that can be output by engine 2 as a function of vehicle speed, and the graph of minimum torque of engine 2 shows the torque when engine 2 is fuel-cut and engine braking is operating (F / C torque) or the combustion lower limit torque as a function of vehicle speed. Both of these values ​​are determined by the characteristics of engine 2.

[0070] The upper margin Mp and the lower margin Mp of the reference torque do not necessarily have to be the same. Alternatively, a margin Mp may be provided only on either the upper or lower side. When the margin Mp is provided above the reference torque, the upper limit of the power running torque range Rp corresponds to the upper limit threshold torque. In other words, the upper limit threshold torque can be said to be a value obtained by adding a predetermined margin Mp (a value corresponding to the predetermined value) above the reference torque. Note that when the predetermined margin Mp is provided only below the reference torque, the upper limit of the power running torque range Rp coincides with the reference torque. In addition to or instead of the upper limit threshold torque, a power running torque range Rp may be set in the control device 5.

[0071] When performing powering motor assist, the control unit 5B synchronizes the rotation speed of the motor 3 with the rotation speed of the output shaft 12 before performing the powering motor assist, and then initiates engagement of the disengaged motor clutch 20. In other words, the control unit 5B performs rotation synchronization control and engages the motor clutch 20 only after preparations for performing powering motor assist are complete (after the rotation speeds are synchronized). Note that "synchronization" here does not only mean that the rotation speed difference is zero (the two rotation speeds are completely the same), but also includes a rotation speed difference that is small enough to cause no problems when engaging the clutch. In other words, the control unit 5B increases the rotation speed of the motor 3 before performing powering motor assist, and when the difference between the rotation speed of the motor 3 and the rotation speed of the output shaft 12 is within a predetermined range, the control unit 5B determines that the rotation speeds are synchronized and initiates engagement of the motor clutch 20.

[0072] When powering motor assist is performed, the driving mode may be switched from parallel mode (while powering motor assist is being performed) to series mode or EV mode, or may remain in parallel mode. In the former case, engine disconnection control is performed. This will be explained using FIG. 6. FIG. 6 is a diagram showing the states of the motor clutch 20 and the engine clutch 30, the driving torque, and the battery power when switching from parallel mode to series mode during powering-side assist control. When switching from parallel mode to series mode, an ENG clutch release mode is performed during the transition.

[0073] The ENG clutch release mode is a driving mode that is implemented from time t1, when engagement of the motor clutch 20 is completed and it is determined that the engine clutch 30 will be released, to time t4, when release of the engine clutch 30 is completed. The engine clutch 30 receives a release command at time t3, when transfer of drive torque from the engine 2 to the motor 3 is completed, and begins to be released.

[0074] When power running motor assist is performed and the driving mode transitions from parallel mode to series mode or EV mode (i.e., a mode in which the power of the engine 2 is not transmitted to the output shaft 12), the control unit 5B starts to decrease the power running torque of the generator 4 and increase the power running torque of the motor 3 at the time when the engine clutch 30 transitions to release (switching time, time t1 in FIG. 6). In this way, by issuing a command to release the engine clutch 30 (while the generator 4 is still outputting power running torque) at a timing before the time when the generator 4 can start generating power (time t2 in FIG. 6), the time required to complete the transition of the driving mode can be shortened.

[0075] Furthermore, even when powering motor assist is being performed, the parallel mode may be maintained as the traveling mode. In this case (when the traveling mode is the parallel mode and the motor clutch 20 is engaged), if the required torque calculated by the calculation unit 5A (hereinafter referred to as the "second required torque") is less than the lower limit of the powering torque range Rp, as shown in FIG. 5 , the control unit 5B disengages the motor clutch 20. In other words, when powering motor assist is being performed while traveling in the parallel mode, the engaged state of the motor clutch 20 is maintained as long as the second required torque does not fall below the lower limit of the powering torque range Rp. In this way, by setting different values ​​for the threshold value used when the motor clutch 20 is disengaged (the upper limit of the powering torque range Rp) and the threshold value used when the motor clutch 20 is engaged (the lower limit of the powering torque range Rp), hunting in the control is prevented.

[0076] Furthermore, when the control unit 5B of this embodiment executes power running motor assist, it first executes power running generator assist while using a short-time SOP to cover the power required to start power running motor assist (specifically, the power required for rotation synchronization) as shown in FIG. 6 . Furthermore, once the control unit 5B is ready to execute power running motor assist, i.e., once it determines that the rotation speeds have been synchronized, it switches to the long-time SOP. Then, while executing power running generator assist using the long-time SOP, it gradually transitions from power running generator assist to power running motor assist. When executing power running motor assist, the control unit 5B may continue to use the long-time SOP, or may temporarily use the short-time SOP to connect to the series mode.

[0077] 5, the control device 5 of this embodiment is set with a second vehicle speed threshold V2 as a vehicle speed value higher than the first vehicle speed threshold V1. The second vehicle speed threshold V2 is a value that takes into account the time required for the motor clutch 20 to be engaged from the released state when the vehicle 1 decelerates, and may be a preset fixed value or a variable value that is set depending on the battery state, outside air temperature, etc. Furthermore, the second vehicle speed threshold V2 does not need to be the same during acceleration and deceleration, and may have hysteresis to prevent adverse effects of switching.

[0078] If the vehicle speed is less than the second vehicle speed threshold V2, the control unit 5B engages the motor clutch 20 regardless of the first required torque. In other words, when the vehicle 1 is traveling in a medium-low vehicle speed range below the second vehicle speed threshold V2, the control unit 5B switches the motor clutch 20 from a disengaged state to an engaged state even if the first required torque does not exceed the upper threshold torque (or upper limit). As a result, for example, when the vehicle 1 decelerates from a high vehicle speed range equal to or greater than the second vehicle speed threshold V2 and falls below the second vehicle speed threshold V2, the motor clutch 20 is reliably engaged before the vehicle speed falls below the first vehicle speed threshold V1 and the engine clutch 30 is disengaged. Therefore, when the vehicle speed decreases from a high vehicle speed range, the drive mode can be quickly transitioned from the parallel mode to the series mode or the EV mode without causing a loss of driving force.

[0079] Furthermore, if the vehicle speed is equal to or greater than the second vehicle speed threshold V2, the control unit 5B determines whether or not to engage the motor clutch 20, which is in the disengaged state, based on the first required torque, as described above. Note that before this determination, the calculation unit 5A calculates the required torque (first required torque or second required torque), and if powering-side assist control is required, powering-generator assist is executed first, as described above.

[0080] Furthermore, if a low gear for transmitting high torque is selected in the engine clutch 30, the control unit 5B engages the motor clutch 20 regardless of the first required torque. A gear for transmitting high torque, such as a low gear, is selected when a large driving force is required, so the selection of this gear indicates that a high torque is likely to be required and responsiveness to accelerator operation is required. When a high gear is selected, the control unit 5B of this embodiment determines whether to engage the motor clutch 20, which is in a disengaged state, based on the first required torque, as described above.

[0081] [4-2. Regeneration-side assist control] Next, the regeneration-side assist control will be described. Note that descriptions overlapping with the powering-side assist control will be omitted. The calculation unit 5A calculates the required torque of the vehicle 1 in the same manner as described above. The calculation unit 5A may also perform the processes of steps A1 and A2 in FIG. 4 in the regeneration-side assist control.

[0082] When the first required torque falls below the minimum torque of the engine 2, the control unit 5B performs regenerative generator assist regardless of whether regenerative motor assist is performed. The minimum torque here is a threshold value used to determine whether regenerative generator assist is required. The minimum torque is the torque during fuel cut of the engine 2 (F / C torque) or the combustion lower limit torque, and is stored in advance in the control device 5.

[0083] As shown in Fig. 4, in the control device 5 of this embodiment, the control unit 5B determines whether the driving mode is in the first state (step B1), and further determines whether the motor clutch 20 is in the disengaged state (step B2). If both determinations are true, the control unit 5B permits generator assist (step B3). Steps B1 to B3 are the same regardless of whether the vehicle is in power running or regeneration mode. The control unit 5B then obtains the required drive shaft torque when the determinations in steps B1 and B2 are both true as the first required torque, determines whether the first required torque is lower than the minimum torque, and if the determinations are true, calculates the regenerative assist torque (step B4).

[0084] The regenerative assist torque calculated here is a torque deficiency that corresponds to the difference between the first required torque and the minimum torque (engine required torque) of the engine 2. Therefore, the calculation of the regenerative assist torque in step B4 uses the result of the calculation of the engine required torque (step B5). Furthermore, the calculation of the engine required torque in step B5 uses the result of the calculation of the required drive shaft torque (step A2) and the result of the calculation of the power generation torque (step B6).

[0085] If the regenerative assist torque is calculated in step B4, the regenerative generator torque to be realized by the regenerative generator assist is calculated based on this regenerative assist torque and the power generation torque calculated in step B6 (step B7). Furthermore, if the regenerative generator assist is handed over to the regenerative motor assist, the regenerative motor torque (motor required torque) is also calculated (step B8), and the connection / disconnection state of the motor clutch 20 is controlled (step B9).

[0086] If the first required torque is smaller than the minimum torque and equal to or greater than a lower threshold torque obtained by subtracting a predetermined value from the minimum torque, the control unit 5B performs regenerative generator assist without performing regenerative motor assist. In other words, if the first required torque is lower than the minimum torque by a predetermined range (hereinafter referred to as the "predetermined range on the regeneration side") (if lower threshold torque≦first required torque<minimum torque), only regenerative generator assist is performed, and regenerative motor assist is not performed. In this case, in step B7, the regenerative assist torque calculated in step B4 may be calculated as the regenerative generator torque.

[0087] Furthermore, when the first required torque is smaller than the lower limit threshold torque, the control unit 5B performs regenerative generator assist and then regenerative motor assist. In other words, when the first required torque is lower than the minimum torque by more than the predetermined range on the regenerative side (when the first required torque is lower than the lower limit threshold torque), both regenerative generator assist and regenerative motor assist are performed. In this way, since regenerative motor assist is not performed unless the first required torque is lower than the minimum torque by more than a predetermined value, the open state of the motor clutch 20 is maintained for a longer period of time even on the regenerative side.

[0088] In this case, for example, the minimum regenerative generator torque (maximum in terms of absolute value) that can be output by the generator 4 may be calculated in step B7, and the torque that cannot compensate for the first required torque with the regenerative generator torque may be calculated as the regenerative motor torque in step B8. Furthermore, after the regenerative generator assist is handed over to the regenerative motor assist, the regenerative assist torque calculated in step B4 may be calculated as the regenerative motor torque in step B8.

[0089] 5, the control device 5 may set a regenerative torque range Rr having a predetermined margin Mr above and / or below the minimum torque. In this case, if the first required torque is smaller than the lower limit of the regenerative torque range Rr, the control unit 5B preferably performs regenerative generator assist and then regenerative motor assist. Furthermore, if the first required torque is smaller than the minimum torque and equal to or greater than the lower limit of the regenerative torque range Rr, the control unit 5B preferably performs only regenerative generator assist.

[0090] The upper margin Mr and the lower margin Mr of the minimum torque do not necessarily have to be the same. Alternatively, a margin Mr may be provided only on either the upper or lower side. When the margin Mr is provided below the minimum torque, the lower limit of the regenerative torque range Rr corresponds to the lower limit threshold torque. In other words, the lower limit threshold torque can be considered a value obtained by adding a predetermined margin Mr (a value corresponding to the predetermined value) below the minimum torque. When the predetermined margin Mr is provided only above the minimum torque, the lower limit of the regenerative torque range Rr coincides with the minimum torque. The control device 5 may set a regenerative torque range Rr in addition to, or instead of, the lower limit threshold torque.

[0091] When executing regenerative motor assist, similarly to powering-side assist control, the control unit 5B synchronizes the rotation speed of the motor 3 with the rotation speed of the output shaft 12 before executing the regenerative motor assist, and then starts engaging the released motor clutch 20. In other words, the control unit 5B performs rotation synchronization control, and engages the motor clutch 20 after preparations for executing regenerative motor assist are complete (after the rotation speeds are synchronized).

[0092] When regenerative motor assist is performed, the driving mode may remain in the parallel mode, or may transition from the parallel mode (when regenerative motor assist is being performed) to the series mode or the EV mode. For example, in the former case (when the driving mode is the parallel mode and the motor clutch 20 is engaged), if the required torque (i.e., the second required torque) calculated by the calculation unit 5A exceeds the upper limit of the regenerative torque range Rr, as shown in FIG. 5 , the control unit 5B disengages the motor clutch 20. In other words, when regenerative motor assist is being performed while driving in the parallel mode, the motor clutch 20 remains engaged unless the second required torque exceeds the upper limit of the regenerative torque range Rr. In this way, by setting different values ​​for the threshold value used when the motor clutch 20 is disengaged (the lower limit of the regenerative torque range Rr) and the threshold value used when the motor clutch 20 is engaged (the upper limit of the regenerative torque range Rr), hunting in the control is prevented.

[0093] 7 and 8 are example flowcharts for explaining the basic processing of the powering-side assist control and the regeneration-side assist control described above. This flowchart is an example of processing performed by the control device 5 (control unit 5B) when the driving mode is the parallel mode and the motor clutch 20 is in an open state, and is performed at a predetermined calculation period. Note that the calculation of the required torque by the calculation unit 5A is performed separately from this flowchart. Also, it is assumed that the vehicle speed is equal to or greater than the second vehicle speed threshold V2 and that the driving mode remains in the parallel mode.

[0094] As shown in FIG. 7 , in step S1, it is determined whether the first required torque is greater than the reference torque. If this is true, the process proceeds to step S2; if not, the process proceeds to step S11 (symbol A) in FIG. 8 . In step S2, it is determined whether the first required torque is greater than the upper limit threshold torque. If this is true, the first required torque exceeds the predetermined range on the powering side, and therefore the processes of steps S3 to S9 (powering generator assist and powering motor assist) are performed. On the other hand, if the determination in step S2 is false, the process proceeds to step S10, where only powering generator assist is performed, and the flow returns.

[0095] In step S3, first, powering generator assist is executed. In the following step S4, it is determined whether or not the motor clutch 20 is fully engaged. If not fully engaged, the processing of step S3 (i.e., powering generator assist) continues, but if fully engaged, the processing proceeds to step S5. In step S5, a transition is made from powering generator assist to powering motor assist. In other words, the proportion of powering generator assist in the powering assist torque is gradually reduced, and the proportion of powering motor assist is gradually increased accordingly.

[0096] Next, in step S6, it is determined whether or not the powering generator assist has ended. For example, it is determined that the powering generator assist has ended when the output ratio of the generator 4, which will be described later, changes from 1 to 0. If the powering generator assist has not ended, the processing of step S5 continues. On the other hand, if the determination in step S6 is affirmative, the processing proceeds to step S7, where only the powering motor assist is executed. In the following step S8, it is determined whether the second required torque, which is the required torque in this state (a state in which the motor clutch 20 is engaged), has fallen below the lower limit of the powering torque range Rp. If this determination is negative, the processing returns to step S7, where the powering motor assist continues to be executed. On the other hand, if the determination in step S8 is affirmative, the processing proceeds to step S9, where the motor clutch 20 is released, powering motor assist is terminated, and the flow returns.

[0097] As shown in FIG. 8 , in step S11, it is determined whether the first required torque is less than the minimum torque of the engine 2. If this is true, the process proceeds to step S12, and if this is not true, the process proceeds to step S21, which will be described later. In step S12, it is determined whether the first required torque is less than a lower limit threshold torque. If this is true, the first required torque is lower than a predetermined range on the regeneration side, and therefore the processes of steps S13 to S19 (regenerative generator assist and regenerative motor assist) are performed. On the other hand, if the determination in step S12 is false, the process proceeds to step S20, where only regenerative generator assist is performed, and the flow returns.

[0098] In step S13, first, regenerative generator assist is executed. In the following step S14, it is determined whether or not the motor clutch 20 is fully engaged. If not fully engaged, the process of step S13 (i.e., regenerative generator assist) continues. If fully engaged, the process proceeds to step S15. In step S15, a transition from regenerative generator assist to regenerative motor assist is made. That is, the proportion of regenerative generator assist in the regenerative assist torque is gradually reduced, and the proportion of regenerative motor assist is gradually increased accordingly.

[0099] Next, in step S16, it is determined whether the regenerative generator assist has ended. This determination is also made, as on the powering side, based on, for example, the output ratio of the generator 4. If the regenerative generator assist has not ended, the processing of step S15 continues. On the other hand, if the determination in step S16 is affirmative, the processing proceeds to step S17, where only the regenerative motor assist is executed. In the following step S18, it is determined whether the second required torque has exceeded the upper limit value of the regenerative torque range Rr. If this is not affirmative, the processing returns to step S17, where the regenerative motor assist continues to be executed. On the other hand, if the determination in step S18 is affirmative, the processing proceeds to step S19, where the motor clutch 20 is released, the regenerative motor assist is ended, and the flow returns.

[0100] In step S21, it is determined whether powering generator assist or regenerative generator assist is being executed. If neither is being executed, the flow returns. If either generator assist is being executed, that generator assist is terminated (step S22), and the flow returns. In other words, if the first required torque is equal to or greater than the minimum torque and equal to or less than the reference torque, the generator assist is not executed.

[0101] [6. Operation] Figures 9(A) to 9(M) are graphs (timing charts) illustrating the operation of powering-side assist control during acceleration, and Figures 10(A) to 9(M) are graphs (timing charts) illustrating the operation of regeneration-side assist control during deceleration. The horizontal axis of these figures represents time. The thick solid line graphs in the figures show changes when the above-mentioned assist controls are implemented (the present invention), and the dashed line graphs in the figures show comparative examples (changes when only motor assist is implemented as conventional technology). Unless otherwise specified, the thick solid line graphs will be described below.

[0102] First, the operation of the powering side assist control will be described. In the powering side assist control described here, a case where the mode is shifted from the parallel mode to the series mode via the ENG clutch release mode will be exemplified.

[0103] As shown in FIGS. 9B and 9C, during running in the parallel mode, at time t 10 Then, the accelerator pedal is released, the vehicle enters a steady state of running, and as shown in Figure 9(D), when the required drive shaft torque falls below the reference torque, a request to release the motor clutch 20 is established (see Figure 9(E)). In this case, the output rate of the generator 4 increases linearly from 0 to 1 (see Figure 9(G)), and at the same time, the generator assist operating state is established (see Figure 9(H)). Note that here, the lower margin Mp of the powering torque range Rp described above is set to 0.

[0104] The output ratio of generator 4 shown in FIG. 9(G) is a parameter that determines whether or not to permit use of generator 4 as an assist, and takes a value greater than or equal to 0 and less than or equal to 1. When the output ratio is 0, use of generator 4 as an assist is prohibited, and when the output ratio is 1, use of generator 4 as an assist is permitted. In the former case, if an assist is necessary, motor 3 is used. When the value of the output ratio is changed, it is changed linearly (at a predetermined slope) rather than in a stepwise manner. This slope determines how long it will take to switch from the powering torque of generator 4 to the powering torque of motor 3 (whether torque transition will occur). This slope is set in advance, for example, through simulation or experiment.

[0105] As shown in (G) and (M) of FIG. 9, at the time t 11 At time t 11 Even if the output rate of generator 4 becomes 1 in this case, generator 4 does not enter power running and simply ends power generation (regeneration), as shown by the dashed line in Fig. 9(M). For this reason, in the conventional system, the required drive shaft torque is smaller than in the present invention (see the dashed line in Fig. 9(D)), and the rate of increase (slope) of vehicle speed is also smaller than in the present invention (see the dashed line in Fig. 9(A)).

[0106] As shown in FIG. 9(M), at time t 11 The reason why the generator required torque is regenerative until time t is that the surplus torque generated by the engine 2 operating at the optimum fuel economy point is used to generate electricity in the generator 4. Here, "equivalent to the optimum fuel economy point" means an operating point (combination of the optimum fuel economy point, engine rotation speed, and engine load) at which the fuel economy of the engine 2 is optimal, and an operating point in the vicinity of this operating point. 11 The engine torque requirement up to time t 11 The generator required torque up to this point is the power generation torque described above (see FIG. 9(M)).

[0107] As shown in FIG. 9B, at time t 12 At time t 13 When the required drive shaft torque exceeds the upper threshold torque, the request to release the motor clutch 20 is not established (release is prohibited) (see FIG. 9(E)). As a result, as shown in FIG. 9(L), the required torque of the motor 3 increases to engage the motor clutch 20, and rotation synchronization of the motor 3 begins (see FIG. 9(I)). During this rotation synchronization, the battery 6 discharges for a short time SOP (see FIG. 9(J)).

[0108] As shown in FIG. 9(I), at time t 14 The rotation synchronization is completed at time t 15 When the engagement of the motor clutch 20 is completed at time t, the release state of the motor clutch 20 is not established (engaged) (see FIG. 9(F)). At this point, as shown in FIG. 9(C), the running mode is changed from the parallel mode to the ENG clutch release mode, and at time t 15 From time t 16 The output rate of the generator 4 decreases linearly from 1 to 0 (see FIG. 9(G)), and the required torque of the generator also decreases accordingly (see FIG. 9(M)). 15 From time t 16 In this case, the motor required torque increases to compensate for the decrease in the generator required torque (see FIG. 9(L)). As a result, the required drive shaft torque is realized (see FIG. 9(D)).

[0109] As shown by the broken line in FIG. 9(M), conventionally, powering generator assist is not performed, and the 13 From the vicinity at time t 15 The generator required torque was maintained at 0 until the time t 159 (M)), the generator required torque is higher than 0. In other words, in the present invention, the ENG clutch release mode is started before the generator required torque becomes less than 0 (regeneration side). Therefore, if the timing at which the generator required torque becomes less than 0 (time t 15 and time t 16 In comparison with the case where the ENG clutch release mode is started at the time between the time when the parallel mode and the series mode are switched on, the time required to switch from the parallel mode to the series mode is shortened.

[0110] Also, as shown in FIG. 9(G), at time t 16 At this time, the generator assist operation state is not established (not in operation) (see FIG. 9(H)). 16 From time t 17 As shown in FIG. 9(M), the generator required torque transitions to the target power generation torque, which is the limit value in the ENG clutch release mode.

[0111] The target power generation torque here is a value that balances with the output torque of the engine 2 when the engine clutch 30 is released. In order to release the engine clutch 30, the generator 4 must be able to receive all of the output torque of the engine 2 at the time of release (standby state), otherwise the engine speed will increase sharply. Setting the generator request torque to the target power generation torque is to put the generator 4 into a state where standby in the series mode is complete. As shown in FIG. 9C, the generator clutch release mode is set to the target power generation torque for a predetermined time (here, time t 15 From time t 17 The reason why the period (up to the start of the power generation) is provided is to match the power generation state of the generator 4 with the output torque of the engine 2.

[0112] As shown in FIG. 9(M), at time t 16 From time t 17 , the motor torque requirement increases further to compensate for the further decrease in the generator torque requirement. 17 At time t18 This completes the transition to series mode.

[0113] Next, the operation of the regeneration-side assist control will be described. Note that explanations that overlap with the operation of the powering-side assist control will be omitted. The regeneration-side assist control described here will exemplify a case in which the parallel mode is maintained. In the example shown in Figures 10(A) to 10(M), first, the driving mode is the parallel mode, and the vehicle is traveling steadily at a high vehicle speed (for example, about 100 km / h) with a constant accelerator opening (see Figures 10(A) to 10(C)).

[0114] In this state, the motor clutch 20 is disengaged (see Figures 10(E) and 10(F)), the engine 2 is operating at a speed equivalent to the best fuel economy point, and the excess torque is generated by the generator 4 (see Figures 10(J), 10(K), and 10(M)). Therefore, in this state, the output rate of the generator 4 is already 1 (see Figure 10(G)), and the generator assist operating state is established (see Figure 10(H)).

[0115] As shown in Figs. 10(B) and 10(D), while the vehicle is running in the above state, at time t 20 When the accelerator pedal is released at time t 20 As shown in FIG. 10(D), the required drive shaft torque decreases from time t 21 When the value of becomes negative, the generator required torque increases further toward the regenerative side, and regenerative generator assist is executed, and the shortage of the required drive shaft torque is assisted by the generator 4 (see FIG. 10(M)). Note that, in the past, as shown by the dashed line in FIG. 10(M), the generator required torque was limited to the power generation torque, so it was not possible to regeneratively assist all of the shortage of the required drive shaft torque.

[0116] Also, as shown in FIG. 10(D), when the required drive shaft torque falls below the lower limit threshold torque (at time t 22 ), the request to release the motor clutch 20 is not satisfied (release is prohibited) (see FIG. 10(E)). In this case, as with the powering-side assist control, the torque required of the motor 3 increases to engage the motor clutch 20, and rotation synchronization of the motor 3 begins (see FIGS. 10(I) and 10(L)).

[0117] As shown in FIG. 10(I), at time t 23 The rotation synchronization is completed at time t 24 When the engagement of the motor clutch 20 is completed at time t, the release state of the motor clutch 20 is not established (engaged) (see FIG. 10(F)). 24 At this time t, the engine torque requirement changes from a positive value to a negative value, and the regenerative generator assist begins to take over to the regenerative motor assist (see (L) and (M) in FIG. 10). 24 Up to this point, the required drive shaft torque is realized by the braking torque of the engine 2 and the regenerative generator torque.

[0118] As shown in FIG. 10(G), at time t 24 From time t 25 The output ratio of the generator 4 decreases linearly from 1 to 0 over the time t 24 From time t 25 In this case, the motor torque requirement increases toward the regeneration side to compensate for the decrease in the generator torque requirement on the regeneration side (see FIG. 10(L)). As a result, the required drive shaft torque is realized by the braking torque of the engine 2 and the regenerative motor torque. Note that, in the conventional system, since the regenerative generator assist is not performed, as shown in FIG. 10(L), 24 From then on, only regenerative assist by motor 3 was performed.

[0119] Also, as shown in FIG. 10(G), at time t 25 At this time, the generator assist operating state is not established (not operating) (see FIG. 10(H)), and the generator required torque shifts to a torque (differential torque) corresponding to the difference between the engine required torque and the fuel cut torque (minimum torque) (see FIGS. 10(K) and 10(M)). 25After this, the motor required torque increases further on the regeneration side to compensate for the further decrease in the generator required torque on the regeneration side, and the handover from regenerative generator assist to regenerative motor assist is completed. Note that when the engine required torque matches the fuel cut torque, the generator required torque becomes zero.

[0120] [7. Effects] (1) In the above-described control device 5, in the vehicle 1 in which regenerative motor assist and regenerative generator assist can be performed in the first state, if the first required torque is low enough to be below the minimum torque, regenerative generator assist is performed regardless of whether regenerative motor assist is being performed. To perform regenerative motor assist, the motor clutch 20 in the open state needs to be engaged, which requires time and power. However, in the above-described control device 5, regenerative generator assist is performed first regardless of whether regenerative motor assist is being performed.

[0121] Therefore, when regenerative motor assist is performed, the timing of engagement of the motor clutch 20 can be delayed (i.e., the motor clutch 20 can be kept open for a long time) while ensuring the required torque with regenerative generator assist, making it less likely that the motor 3 will rotate together, reducing the frequency of flux weakening control and reducing power consumption. Furthermore, when regenerative motor assist is not performed, the required torque can be ensured with regenerative generator assist, without consuming the power required to engage the motor clutch 20, thereby reducing power consumption. Therefore, with the control device 5 described above, power consumption can be reduced by making clever use of the generator 4 when the required torque decreases, thereby improving electric efficiency.

[0122] In the above-described control device 5, in the powering-side assist control, when the first required torque is high enough to exceed the reference torque, the powering-generator assist is executed regardless of whether the powering-motor assist is executed or not, similarly to the powering-side assist control. Therefore, power consumption can be suppressed on the powering side as well, and electric efficiency can be improved.

[0123] (2) In the control device 5 described above, if the first required torque is lower than the minimum torque by within a predetermined range on the regeneration side (if the lower limit threshold torque is equal to or lower than the first required torque < the minimum torque), regenerative motor assist is not performed. Also, if the first required torque is lower than the minimum torque by more than a predetermined range on the regeneration side (if the first required torque < the lower limit threshold torque), regenerative generator assist is performed, followed by regenerative motor assist. In other words, since regenerative motor assist is not performed unless the first required torque is lower than the minimum torque by more than a predetermined value, the motor clutch 20 can be maintained in an open state for a longer period of time. This allows for further reduction in power consumption.

[0124] (3) In the above-described control device 5, in the powering-side assist control, as in the regeneration-side assist control, if the first required torque exceeds the reference torque by more than a predetermined range on the powering side (if reference torque < first required torque ≦ upper limit threshold torque), powering motor assist is not performed. Furthermore, if the first required torque exceeds the reference torque by more than a predetermined range on the powering side (if upper limit threshold torque < first required torque), powering generator assist is performed, and then powering motor assist is performed. In other words, powering motor assist is not performed unless the first required torque exceeds the reference torque by more than a predetermined value, so the motor clutch 20 can be maintained in an open state for a longer period of time. This allows for further reduction in power consumption.

[0125] (4) The control device 5 described above may further define a regenerative torque range Rr (see FIG. 5) having a predetermined margin Mr above and / or below the minimum torque. In this case, if the first required torque is smaller than the lower limit of the regenerative torque range Rr, the control unit 5B performs regenerative generator assist and then regenerative motor assist. In other words, since regenerative motor assist is not performed unless the first required torque falls below the lower limit of the regenerative torque range Rr, the motor clutch 20 can be kept in an open state for a longer period of time. This allows for further reduction in power consumption.

[0126] In the above-described control device 5, in the powering-side assist control, a powering torque range Rp (see FIG. 5) having a predetermined margin Mp above and / or below the reference torque may be set, as in the regeneration-side assist control. In this case, if the first required torque is greater than the upper limit of the powering torque range Rp, the control unit 5B performs powering generator assist and then powering motor assist. In other words, powering motor assist is not performed unless the first required torque exceeds the upper limit of the powering torque range Rp, so the motor clutch 20 can be maintained in an open state for a longer period of time. This allows for further reduction in power consumption.

[0127] (5) When performing regenerative motor assist, the above-described control unit 5B synchronizes the rotation speed of the motor 3 with the rotation speed of the output shaft 12 and then starts engaging the motor clutch 20, which is in a disengaged state. This rotation synchronization control consumes power from the battery 6, but if the frequency of performing regenerative motor assist is reduced, power consumption can be reduced. Note that the above-described control device 5 also performs rotation synchronization control in powering side assist control, just as in regenerative side assist control, but if the frequency of performing powering motor assist is reduced, power consumption can be reduced.

[0128] (6) When performing power running motor assist, the control unit 5B of this embodiment starts to reduce the power running torque of the generator 4 and increase the power running torque of the motor 3 when the traveling mode transitions from the parallel mode to the series mode or the EV mode (time t 15 9C]. As a result, as explained above, the time required to complete the transition from the parallel mode to the series mode can be shortened. This makes it possible to improve driving performance (e.g., acceleration performance) when driving at high vehicle speeds.

[0129] (7) When performing power running motor assist, the control unit 5B of this embodiment performs power running generator assist while using the short-term SOP to cover the power required to start power running motor assist, and then returns to the long-term SOP once preparations for power running motor assist are complete. This allows power running generator assist to be performed using a constant battery power while also completing preparations for power running motor assist, thereby improving the driving performance of the vehicle 1.

[0130] (8) In the control device 5 described above, a first vehicle speed threshold V1 and a second vehicle speed threshold V2 may be set as shown in FIG. 5 . In this case, the control unit 5B engages the motor clutch 20 regardless of the first required torque if the vehicle speed is less than the second vehicle speed threshold V2. As a result, for example, when the vehicle 1 decelerates from a high vehicle speed range equal to or greater than the second vehicle speed threshold V2 and falls below the second vehicle speed threshold V2, the motor clutch 20 is reliably engaged before the vehicle speed falls below the first vehicle speed threshold V1 and the engine clutch 30 is released. This makes it possible to avoid loss of driving force and quickly transition from the parallel mode to the series mode or the EV mode, thereby improving drivability.

[0131] [8. Other] The above-described control device 5 and vehicle 1 are merely examples and are not limited to the above-described configurations. For example, in the control device 5, the second vehicle speed threshold V2 may be omitted and there may be only one vehicle speed threshold. Furthermore, when performing power running motor assist, the timing of issuing a command to release the engine clutch 30 does not have to coincide with the switching time when the power running torque of the generator 4 starts to decrease and the power running torque of the motor 3 starts to increase.

[0132] The required torque calculated by calculation unit 5A is not limited to that based on the driver's operation (mainly accelerator operation), and may be calculated as the required torque of vehicle 1 when accelerating or decelerating automatically (without driver operation) by ACC (Adaptive Cruise Control). Furthermore, control unit 5B may be configured not to distinguish between the long-term SOP and the short-term SOP of battery 6, and even if it does distinguish between them, the distinction is not limited to the distinction described above (or shown in FIG. 9 ).

[0133] The control device 5 described above performs powering-side assist control and regeneration-side assist control, and is capable of providing appropriate assistance in any driving situation, but it may also be possible to execute only the regeneration-side assist control and omit the powering-side assist control, in which case the configuration related to the powering-side assist control can be omitted.

[0134] In the above-described embodiment, the transaxle 10 is illustrated as having the engine clutch 30 (or a part of the engine clutch 30) that switches between a high gear and a low gear mounted on the first countershaft 15. However, the location of the engine clutch 30 is not particularly limited, and it may be mounted on the input shaft 11, or may be mounted across the input shaft 11 and the first countershaft 15. The engine clutch 30 described above has a function as a connecting / disconnecting mechanism and a high / low switching function (a mechanism for selecting between a high gear and a low gear), but these functions may be provided as separate mechanisms, or the latter function may be omitted. The engine clutch 30 is not an essential component of the present invention and may be omitted if possible.

[0135] The configuration of the transaxle 10 is also one example. For example, the relative positions of the engine 2, motor 3, and generator 4 with respect to the transaxle 10 are not limited to those described above. The arrangement of the six shafts 11 to 16 within the transaxle 10 may be set according to these relative positions. The arrangement of the gears provided on each shaft within the transaxle 10 is also one example and is not limited to that described above. While the motor clutch 20 is mounted on the motor shaft 13, the arrangement of the motor clutch 20 is not limited to this. The motor clutch 20 may be mounted on the second countershaft 16, or may be mounted across the motor shaft 13 and the second countershaft 16. The vehicle 1 does not necessarily need to have multiple power transmission paths configured as the transaxle 10.

[0136] REFERENCE SIGNS LIST 1 vehicle 2 engine 3 motor 4 generator 5 control device 5A calculation unit 5B control unit 6 battery 8 drive wheels 12 output shaft 20 motor clutch 51 first path (first power transmission path) 52 second path (second power transmission path) 53 third path (third power transmission path) 54 fourth path (fourth power transmission path) Mp, Mr margin Rp powering torque range Rr regenerative torque range

Claims

1. A control device for a vehicle including a drive battery, a first power transmission path from a motor to an output shaft on the drive wheel side, a second power transmission path from an engine to the output shaft that is separate from the first power transmission path, a third power transmission path from the engine to a generator, a fourth power transmission path from the generator to the output shaft, and a motor clutch provided on the first power transmission path for connecting and disconnecting power transmission, wherein the vehicle is configured to be able to execute a regenerative motor assist that transmits regenerative torque of the motor to the output shaft in a first state in which power transmission is possible between the engine and the output shaft, and a regenerative generator assist that transmits regenerative torque of the generator to the output shaft in the first state, excluding power generation torque generated by the generator generating electricity when the engine is operated at a speed equivalent to the best fuel efficiency point, and the control device comprises: a calculation unit that calculates a required torque of the vehicle; a control unit that performs the regenerative generator assist regardless of whether the regenerative motor assist is performed or not when a first required torque, which is the required torque calculated by the calculation unit in the first state and with the motor clutch in an open state, falls below a minimum torque of the engine.

2. The vehicle control device described in claim 1, characterized in that the control unit performs the regenerative generator assist without performing the regenerative motor assist when the first required torque is smaller than the minimum torque and is equal to or greater than a lower threshold torque obtained by subtracting a predetermined value from the minimum torque, and performs the regenerative generator assist and then the regenerative motor assist when the first required torque is smaller than the lower threshold torque.

3. The vehicle control device described in claim 1, characterized in that the control device further sets a regenerative torque range having a predetermined margin above and / or below the minimum torque, and the control unit executes the regenerative generator assist and then the regenerative motor assist if the first required torque is smaller than the lower limit value of the regenerative torque range.

4. A vehicle control device as described in claim 2 or 3, characterized in that when performing the regenerative motor assist, the control unit synchronizes the rotation speed of the motor with the rotation speed of the output shaft side and then engages the motor clutch, which is in an open state.

5. A vehicle control device according to claim 1 or 2, wherein the vehicle is configured to be able to execute a powering motor assist that transmits the powering torque of the motor to the output shaft in the first state, and a powering generator assist that transmits the powering torque of the generator to the output shaft in the first state, and the control unit executes the powering generator assist without executing the powering motor assist when the first required torque is greater than a predetermined reference torque and is equal to or less than an upper threshold torque obtained by adding a second predetermined value to the reference torque, and executes the powering generator assist and then the powering motor assist when the first required torque is greater than the upper threshold torque.

Images