Control system for hybrid vehicles

Abstract

To suppress influence of clutch engagement at the time of re-startup of an engine on cooperative regenerative control and switching of braking, in a hybrid vehicle mounted with a P2 module.SOLUTION: A control device of a hybrid vehicle includes an engine 4, a motor 5, a K0 clutch 6, a drive shaft 17, a frictional brake system 3 of a fluid pressure type, and a controller 20 that can perform cooperative regenerative control. When startup of the engine 4 is requested during cooperative regenerative control, the controller 20 performs first processing of making a transition to braking only by the frictional brake system 3. After the transition of the braking is completed, the controller 20 performs second processing of increasing the output rotation speed of the engine 4 while starting engagement of the K0 clutch 6. After the engagement of the K0 clutch 6 is started, the controller 20 performs third processing of causing the engine 4 to resume operation at a timing after the engine rotation speed has been increased up to matching the motor rotation speed.SELECTED DRAWING: Figure 7

Description

Technical Field

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[0001] This disclosure relates to a control device for a hybrid vehicle.

Background Art

[0002] For example, Patent Document 1 discloses a control device for a hybrid vehicle. This hybrid vehicle is a vehicle equipped with a so-called P2 module.

[0003] Specifically, the hybrid vehicle disclosed in Patent Document 1 includes an engine, a first friction engagement element, a motor generator fastened to the engine via the first friction engagement element, a second friction engagement element interposed between the motor generator and the drive wheels, and cooperative regeneration control means.

[0004] The cooperative regeneration control execution means disclosed in Patent Document 1 prohibits an increase in regeneration torque from when the mechanical brake is operated and the friction engagement element is in a slipping state (for example, at engine startup) until a predetermined time has elapsed after the friction engagement element is fastened. According to Patent Document 1, by prohibiting an increase in regeneration torque, it is possible to prevent the occurrence of shocks due to unintended slips.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, in the case of a hybrid vehicle equipped with a P2 module as disclosed in Patent Document 1, cooperative regenerative control is usually performed with the clutch between the engine and the motor disengaged when the brake pedal is operated. This cooperative regenerative control brakes the drive wheels through the coordination of braking force applied by the brake system and regenerative action by the motor.

[0007] Furthermore, there are times when the engine needs to be restarted even while the brake pedal is being operated (i.e., during coordinated regenerative braking), such as when the vehicle enters a curve or when the air conditioner is activated while decelerating.

[0008] In this case, it is conceivable to switch from braking by coordinated regenerative control to braking using only the brake system, and to connect the engine and motor by engaging the clutch in order to increase the engine's output speed.

[0009] However, with a hydraulic brake system, it is not possible to switch between braking modes instantaneously. Similarly, when connecting the engine and motor, a certain amount of time is required between engaging the clutch and the engine and motor's respective output rotational speeds matching.

[0010] Therefore, if the braking switch and clutch engagement are initiated almost simultaneously, the two processes will proceed concurrently. In this case, the adjustment of the engine's output speed, such as changing the motor's regenerative operation when the engine's output speed does not change smoothly, may affect the coordinated regenerative control and the switching of braking from that coordinated regenerative control.

[0011] For example, if there is a delay in the increase in engine output speed, it may be necessary to force the motor to perform acceleration during regenerative braking or to reduce the regenerative force (regenerative braking torque) from the motor. However, such processing is inconvenient because it complicates the coordinated regenerative control.

[0012] This disclosure has been made in view of the above, and its purpose is to suppress the influence of clutch engagement during engine restart on the switching between cooperative regenerative control and braking in a hybrid vehicle equipped with a P2 module. [Means for solving the problem]

[0013] This disclosure relates to a control device for a hybrid vehicle, comprising: an engine that generates driving force for the vehicle; a motor capable of performing a propulsion operation and a regenerative operation, respectively; a first clutch interposed between the engine and the motor, which can be switched between a connected state in which the engine and the motor are fastened together and a disconnected state in which the fastening is released; and an axle interposed between the motor and the drive wheels of the vehicle. This control device comprises: a hydraulic friction brake system that distributes braking force to the drive wheels in response to the driver's operation of the brake pedal; and a control means capable of performing coordinated regenerative control, while the first clutch is disengaged, which performs braking by the coordination of the distribution of the braking force by the friction brake system and the application of regenerative braking torque to the drive wheels by causing the motor to perform a regenerative operation during vehicle deceleration when the brake pedal is operated.

[0014] Furthermore, according to one aspect of the present disclosure, when the engine is requested to start during the cooperative regenerative control, the control means performs a first process of transitioning from braking by the cooperative regenerative control to braking by the friction brake system alone; a second process of increasing the engine's output speed by causing the motor to perform the traction operation or the regenerative operation while starting to engage the first clutch after the transition to braking by the friction brake system alone is completed; and a third process of restarting the engine after the engine's output speed has increased to match the motor's output speed, following the start of engagement of the first clutch.

[0015] According to this configuration, the hybrid vehicle is a hybrid vehicle equipped with a so-called P2 module, which is connected in such a way that the driving force is transmitted in the order of engine, first clutch, motor, second clutch, axle, and drive wheels.

[0016] Then, while the vehicle is decelerating and the friction brake system is distributing braking force to the drive wheels, the motor performs regenerative braking. This control is coordinated regenerative control by the friction brake system and the motor. Coordinated regenerative control increases the regenerative energy stored in the battery, etc. The regenerative braking torque from the motor is applied to the drive wheels. The friction brake system distributes braking force to the drive wheels, taking into account the regenerative braking torque applied to the drive wheels. As a result, the braking acting on the hybrid vehicle becomes braking that corresponds to the driver's brake pedal operation.

[0017] Here, when the engine is requested to start during the cooperative regenerative control, the control means increases the engine's output speed after the transition from braking by cooperative regenerative control to braking by the friction brake system alone is completed.

[0018] Therefore, when the engine's power output speed adjustment begins, the braking switch has already been completed. As a result, the influence of the power output speed adjustment on the coordinated regenerative control and the switching from that coordinated regenerative control to braking can be suppressed.

[0019] Furthermore, in one embodiment described above The control device of the hybrid vehicle includes a second clutch interposed between the motor and the axle, which can be switched between a connected state in which the motor and the axle are fastened together and a disconnected state in which the fastening is released. The second clutch is fastened when the cooperative regenerative control is performed, and the control means causes the second clutch to slip if the motor's output rotational speed falls below a predetermined rotational speed after the first clutch has been fastened in the second process. 。

[0020] According to this configuration, when a predetermined condition is satisfied, the second clutch is slipped. By slipping the second clutch, the rotational resistance of the motor can be reduced. Thereby, it becomes possible to suppress a decrease in the output rotational speed of the motor.

[0021] Here, when there is no association between the timing of slipping the second clutch and the timing of switching to braking only by the friction brake system as in a conventionally known configuration (for example, when the two processes are started simultaneously), there is a possibility that the second clutch is slipped without the braking switch being completed.

[0022] In this case, since the regeneration operation is performed in a state where the power transmission between the motor and the drive wheels is suppressed, the regenerative braking torque applied by the motor is not sufficiently transmitted to the drive wheels, and there is a possibility of G - loss.

[0023] On the other hand, in the case of the above - mentioned configuration, the second clutch is slipped after the braking switch is completed. Thereby, in a state where the application of the regenerative braking torque is finished (for example, in a state where the regenerative braking torque is reduced to substantially zero), the second clutch starts to slip. Thereby, the occurrence of G - loss can be suppressed.

[0024] Also, according to one aspect of the present disclosure, the control means may be configured to, after matching the output rotational speed of the engine with the output rotational speed of the motor in the third process, when the output rotational speeds of the engine and the motor drop below a predetermined idle rotational speed, release or slip the second clutch and control the engine so as to increase the output rotational speed to be equal to or higher than the idle rotational speed.

[0025] According to this configuration, after the engine is restarted, the output rotational speeds of the engine and the motor can be maintained at an idle rotational speed or higher. Thereby, when an acceleration request is made to the hybrid vehicle, such as when switching from depressing the brake pedal to depressing the accelerator pedal, the vehicle can be smoothly accelerated.

[0026] Further, according to one aspect of the present disclosure, the control means may determine that the start of the engine is requested when the steering wheel angle exceeds a predetermined value during the cooperative regeneration control.

[0027] According to this configuration, when the steering wheel is operated during deceleration when the brake pedal is depressed (that is, during the execution of the cooperative regeneration control), the control means executes the first process, the second process, and the third process. Thereby, for example, when a hybrid vehicle enters a corner while depressing the brake pedal, the engine can be smoothly restarted without causing problems such as G-drop. Thus, so-called slow-in / fast-out can be realized more smoothly than in conventional hybrid vehicles. Thereby, the operability of the hybrid vehicle can be improved.

[0028] Further, according to one aspect of the present disclosure, the control means may determine that the start of the engine is requested when the air conditioner switch is turned on during the cooperative regeneration control.

[0029] According to this configuration, when the air conditioner switch is operated during deceleration when the brake pedal is depressed (that is, during the execution of the cooperative regeneration control), the control means executes the first process, the second process, and the third process. Thereby, for example, when driving of the air conditioner is desired when the brake pedal is depressed, the engine can be smoothly restarted without causing problems such as G-drop. Thus, the shock at the time of engine restart can be suppressed. Thereby, the riding comfort of the hybrid vehicle can be improved.

Advantages of the Invention

[0030] As described above, according to the present disclosure, in a hybrid vehicle equipped with a P2 module, it is possible to suppress the influence of clutch engagement at the time of engine restart on cooperative regeneration control and braking switching. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 shows a hybrid vehicle. [Figure 2] Figure 2 shows the fastening table for an automatic transmission. [Figure 3A] Figure 3A is a block diagram of the control system for a hybrid vehicle. [Figure 3B] Figure 3B is a block diagram of the friction brake system. [Figure 4] Figure 4 is a flowchart illustrating the processes related to the engine. [Figure 5] Figure 5 is a flowchart illustrating the processes related to the motor and brake. [Figure 6] Figure 6 is a flowchart illustrating the process related to restart control. [Figure 7] Figure 7 shows the time charts for the first, second, and third processes. [Modes for carrying out the invention]

[0032] The following describes an embodiment of the control system for a hybrid vehicle. The following description is illustrative.

[0033] (Hybrid vehicles) Figure 1 shows an automobile 1 (vehicle and an example of a hybrid vehicle) to which the present disclosure applies. This automobile 1 is a hybrid vehicle capable of running using electricity. The automobile 1 has a total of four wheels: two front wheels 2F and two rear wheels 2R. Friction brakes 31 are attached to both the front wheels 2F and the rear wheels 2R to brake their rotation.

[0034] Automobile 1 is equipped with an engine 4 and a motor 5 as drive sources, which generate the driving force for the automobile 1. These work together to drive the rear wheels 2R, thereby causing automobile 1 to move. Automobile 1 is a rear-wheel drive vehicle. Motor 5 is used not only as a drive source but also as a generator during regeneration. That is, motor 5 in this embodiment can perform both a powering operation that generates the driving force for the automobile 1 and a regenerative operation that supplies regenerative energy to a battery (high-voltage battery 9 described later) when automobile 1 decelerates.

[0035] As described later, this vehicle 1 is equipped with a high-voltage battery 9 with a rated voltage of 50V or less. Power supplied from this high-voltage battery 9, the motor 5 primarily assists the engine 4 in driving the vehicle. Vehicle 1 is a so-called mild hybrid vehicle. Vehicle 1 may also be a so-called plug-in hybrid vehicle that can receive power from an external power source.

[0036] Furthermore, the automobile 1 is a hybrid vehicle equipped with a so-called P2 module, in which the driving force is transmitted in the following order: engine 4, first clutch (K0 clutch 6), motor 5, second clutch (K1 clutch 8d), axle (drive shaft 17), and drive wheels (rear wheels 2R).

[0037] In this automobile 1, the engine 4 is located at the front of the vehicle, and the drive wheels are located at the rear of the vehicle. In other words, this automobile 1 is a so-called FR (front-engine, rear-wheel drive) vehicle.

[0038] Automobile 1 is equipped with an engine 4, a motor 5, and as part of its drivetrain, a K0 clutch 6, an inverter 7, and an automatic transmission 8. Automobile 1 is also equipped with a controller 20 as part of its control system. Automobile 1 is also equipped with a hydraulic friction brake system 3, including a friction brake 31, as part of its braking system.

[0039] (Drive system components) Engine 4 is an internal combustion engine that burns, for example, fossil fuels. Engine 4 is also a so-called four-stroke engine that generates rotational power by repeating the intake, compression, expansion, and exhaust cycles. Engine 4 is configured as a diesel engine classified as a compression-ignition engine, but it may be of various types and forms, such as a spark-ignition engine or other compression-ignition engines. Engine 4 operates by injecting fuel such as fossil fuels and burning that fuel in the cylinder.

[0040] In this automobile 1, the engine 4 is positioned approximately in the center of the vehicle width direction, with the crankshaft 4a that outputs rotational power facing in the front-to-rear direction of the vehicle body. The automobile 1 is equipped with various devices and mechanisms associated with the engine 4, such as an intake system, an exhaust system, and a fuel supply system.

[0041] Motor 5 is a permanent magnet type synchronous motor driven by three-phase alternating current. Motor 5 is located in series behind the engine 4 via the K0 clutch 6. Motor 5 is also located in series in front of the automatic transmission 8.

[0042] The K0 clutch 6 is interposed between the engine 4 and the motor 5. More specifically, the K0 clutch 6 is installed so as to be interposed between the front end of the shaft 5a of the motor 5 and the crankshaft 4a of the engine 4. The K0 clutch 6 switches between a state in which the crankshaft 4a and shaft 5a are connected (connected state) and a state in which the crankshaft 4a and shaft 5a are separated (separated state).

[0043] The K0 clutch 6 is engaged when the engine 4 and motor 5 are locked together. The K0 clutch 6 is disengaged when its engagement is released (disconnected). The K0 clutch 6 functions as the "first clutch" in this embodiment. Switching between the engaged and disengaged states of the K0 clutch 6 as the first clutch is performed by hydraulic control by the first hydraulic circuit 13 (shown only in Figure 3A).

[0044] The rear end of the motor 5's shaft 5a is connected to the input shaft 8a of the automatic transmission 8. Therefore, the engine 4 is connected to the automatic transmission 8 via the K0 clutch 6 and shaft 5a. By disengaging the K0 clutch 6, the engine 4 is disconnected from the automatic transmission 8.

[0045] While the vehicle 1 is in motion, the K0 clutch 6 is switched between an engaged state and an engaged state. For example, when the vehicle 1 is decelerating, the K0 clutch 6 may be put into the engaged state, and regeneration may be performed with the engine 4 disconnected. For example, in the coordinated regenerative control described later, the motor 5 is able to perform regenerative operation with the K0 clutch 6, which acts as the first clutch, disengaged. In addition, the K1 clutch 8d, which acts as the second clutch, is engaged when the coordinated regenerative control is executed.

[0046] The motor 5 is connected to a high-voltage battery 9 mounted on the vehicle as a power source via an inverter 7 and a high-voltage cable 40. In the case of this automobile 1, the high-voltage battery 9 is a DC battery with a rated voltage of 50V or less, specifically a 48V battery.

[0047] The high-voltage battery 9 supplies a high-voltage direct current to the inverter 7. The inverter 7 converts this direct current into three-phase alternating current and energizes the motor 5. This causes the motor 5 to rotate. The motor 5 also supplies regenerative energy back to the high-voltage battery 9.

[0048] The high-voltage battery 9 is also connected to the DC-DC converter 10 via a high-voltage cable 40. The DC-DC converter 10 converts a high-voltage DC voltage of 48V to a low-voltage DC power of 12V and outputs it. The DC-DC converter 10 (its output side) is connected to the low-voltage battery 11 (a so-called lead-acid battery) via a low-voltage cable 41.

[0049] The low-voltage battery 11 is connected to various electrical components via the low-voltage cable 41. The DC-DC converter 10 is also connected to the CAN (Controller Area Network) 12 via the low-voltage cable 41. As a result, the DC-DC converter 10 supplies low-voltage DC power to the CAN 12.

[0050] The automatic transmission 8 is a hydraulically controlled multi-stage automatic transmission (so-called AT). This automatic transmission 8 has an input shaft 8a connected to the engine 4 and an output shaft 8b connected to the drive wheels (rear wheels 2R) of the automobile 1. This automatic transmission 8 can output the rotation input to the input shaft 8a at a gear ratio corresponding to the gear selected by the occupant.

[0051] More specifically, the input shaft 8a is located at the front end of the automatic transmission 8. This input shaft 8a is connected to the shaft 5a of the motor 5, as described above. The output shaft 8b is located at the rear end of the automatic transmission 8. This output shaft 8b rotates independently of the input shaft 8a.

[0052] Between the input shaft 8a and the output shaft 8b, a speed change mechanism consisting of a torque converter 8c, multiple planetary gear mechanisms, and multiple friction fastening elements is incorporated. Each friction fastening element is switched between a fastened state and a disfastened state by hydraulic pressure.

[0053] Figure 2 shows the engagement table for this automatic transmission 8. Circles in the table indicate engagement. This automatic transmission 8 incorporates three clutches, consisting of a first clutch CL1, a second clutch CL2, and a third clutch CL3, as friction engagement elements, and two brakes, consisting of a first brake BR1 and a second brake BR2. The automatic transmission 8 also has a second hydraulic circuit 8e (shown only in Figure 3A) for switching these friction engagement elements between an engaged state (connected state) and an unengaged state (disconnected state).

[0054] The automatic transmission 8, under hydraulic control by the second hydraulic circuit 8e, selects and engages three elements from these three clutches and two brakes. In doing so, the automatic transmission's gears switch to either forward gears from 1st to 8th gear, or reverse gears (reverse speed).

[0055] Specifically, the engagement of the first clutch CL1, the first brake BR1, and the second brake BR2 forms the first gear. The engagement of the second clutch CL2, the first brake BR1, and the second brake BR2 forms the second gear. The engagement of the first clutch CL1, the second clutch CL2, and the second brake BR2 forms the third gear. The engagement of the second clutch CL2, the third clutch CL3, and the second brake BR2 forms the fourth gear. The engagement of the first clutch CL1, the third clutch CL3, and the second brake BR2 forms the fifth gear. The engagement of the first clutch CL1, the second clutch CL2, and the third clutch CL3 forms the sixth gear. The engagement of the first clutch CL1, the third clutch CL3, and the first brake BR1 forms the seventh gear. The engagement of the third clutch CL3, the first brake BR1, and the second brake BR2 creates the reverse speed.

[0056] For example, when shifting up from 1st gear, the gear changes from 1st to 2nd gear by engaging the 2nd clutch CL2 instead of the 1st clutch CL1. The gear changes from 2nd to 3rd gear by engaging the 1st clutch CL1 instead of the 1st brake BR1. The gear changes from 3rd to 4th gear by engaging the 3rd clutch CL3 instead of the 1st clutch CL1.

[0057] Shifting up to 5th gear and beyond is done in the same way. Shifting down follows the reverse procedure of shifting up.

[0058] If the elements that should be fastened at each gear are not fastened, the input shaft 8a and the output shaft 8b will be disconnected (so-called neutral). Even if rotational power is input to the automatic transmission 8 from the drive source, that rotational power will not be output from the automatic transmission 8.

[0059] In this embodiment, the automatic transmission 8 may be put into neutral when the second clutch CL2 or the third clutch CL3 is released while the automobile 1 is decelerating. Specifically, when the automatic transmission 8 is in 2nd, 3rd, or 4th gear, the automatic transmission 8 will be put into neutral when the second clutch CL2 is released. Also, when the automatic transmission 8 is in 5th, 6th, 7th, or 8th gear, the automatic transmission 8 will be put into neutral when the third clutch CL3 is released.

[0060] In the following explanation, these second clutch CL2 and third clutch CL3 may be collectively referred to as the K1 clutch 8d (see Figure 3A). When the vehicle 1 is decelerating, releasing the K1 clutch 8d means interrupting the power transmission between the input shaft 8a and the output shaft 8b of the automatic transmission 8, thereby putting the automatic transmission 8 into neutral.

[0061] As shown in Figure 1, the output shaft 8b of the automatic transmission 8 is connected to the differential gear 16 via a propeller shaft 15 that extends in the longitudinal direction of the vehicle body. A pair of drive shafts 17, 17 are connected to the differential gear 16, extending in the width direction of the vehicle and connected to the left and right rear wheels 2R, 2R. The rotational power output through the propeller shaft 15 is distributed by the differential gear 16 and then transmitted to each rear wheel 2R through this pair of drive shafts 17, 17. The pair of drive shafts 17, 17 function as an "axle" interposed between the motor 5 and the drive wheels (left and right rear wheels 2R, 2R).

[0062] While the vehicle 1 is in motion, the K1 clutch 8d is switched between a engaged state and a disengaged state. Here, the engaged state of the K1 clutch 8d is when the motor 5 and the pair of drive shafts 17, 17, which act as drive wheels, are coupled together. The disengaged state of the K1 clutch 8d is when the coupling is released (disconnected).

[0063] The K1 clutch 8d functions as the "second clutch" in this embodiment. As described above, the switching between the connected and disconnected states of the K1 clutch 8d as the second clutch is performed by hydraulic control by the second hydraulic circuit 8e.

[0064] (Control device for hybrid vehicles) Figure 3A is a block diagram of the control system for a hybrid vehicle. The vehicle 1 is equipped with the aforementioned controller 20, which controls the engine 4, motor 5, K0 clutch 6, automatic transmission 8, friction brake system 3, etc., in response to the driver's input, and controls the driving of the vehicle 1.

[0065] The controller 20 consists of hardware such as a processor, memory, and interface, and software such as a database and control programs. Although Figure 3A shows a single controller 20, the controller of the control device may be divided into a unit (PCM) that mainly controls the operation of the drive source (engine 4 and motor 5) and a unit (TCM) that mainly controls the operation of the K0 clutch 6 and automatic transmission 8. The PCM and TCM are connected by CAN 12 and are configured to communicate with each other electrically. The PCM also serves as a brake ECU for controlling the friction brake system 3. The brake ECU may be separated from the PCM. The controller 20 functions as the "control means" in this embodiment.

[0066] The control system of a hybrid vehicle includes sensors that measure various parameters related to the vehicle's operation, and switches that detect driver operations. Specifically, the gear shift control system includes a vehicle speed sensor 51, a steering angle sensor 52, a brake pedal sensor 53, an accelerator pedal position sensor 54, an engine speed sensor 55, a motor speed sensor 56, and an A / C switch 71.

[0067] The vehicle speed sensor 51 outputs a signal corresponding to the vehicle speed. The steering angle sensor 52 outputs a signal corresponding to the rotation angle of the steering wheel 110 (see Figure 1) operated by the driver, i.e., the steering angle (steering angle).

[0068] The brake pedal sensor 53 outputs a signal corresponding to the degree to which the brake pedal 19 (see Figure 1) is pressed by the driver. The accelerator pedal position sensor 54 outputs a signal corresponding to the degree to which the accelerator pedal 18 (see Figure 1) is pressed by the driver.

[0069] The engine rotation sensor 55 outputs a signal corresponding to the output rotation speed of the engine 4 (engine rotation speed), that is, the rotation speed of the crankshaft 4a. The motor rotation sensor 56 outputs a signal corresponding to the output rotation speed of the motor 5 (motor rotation speed), that is, the rotation speed of the motor 5's shaft 5a and also the rotation speed of the input shaft 8a of the automatic transmission 8.

[0070] The A / C switch 71 is a switch for switching the air conditioner 72 (shown only in Figure 3A) between the ON and OFF states. When the driver turns on the air conditioner 72 to the ON state, the A / C switch 71 outputs a signal corresponding to that ON operation.

[0071] The controller 20 receives signals output by these sensors and switches via CAN 12. The controller 20 outputs control signals via CAN 12 to the engine 4, inverter 7, first hydraulic circuit 13, second hydraulic circuit 8e, air conditioner 72, and friction brake system 3. As a result, the controller 20 controls the engine 4, motor 5, K0 clutch 6, automatic transmission 8, air conditioner 72, and friction brake system 3.

[0072] For example, when the A / C switch 71 is turned on to activate the air conditioner 72, the controller 20 uses the driving force of the engine 4 to operate the compressor of the air conditioner 72.

[0073] In addition, the controller 20 controls the friction brake system 3 to brake the automobile 1. Figure 3B is a block diagram of the friction brake system 3. The friction brake system 3 shown in Figure 3B distributes braking force to the front wheels 2F and rear wheels 2R of the automobile 1 in response to the operation of the brake pedal 19, so as to achieve braking when the driver operates the brake pedal 19. This friction brake system 3 is a hydraulically controlled friction brake system.

[0074] As shown in Figure 3B, the friction brake system 3 comprises the four friction brakes 31 described above (only one is shown in Figure 3B), a master cylinder 32, and a brake mechanism 33.

[0075] The master cylinder 32 transmits the pedaling force applied to the brake pedal 19 to the brake fluid and converts it into hydraulic pressure. The brake mechanism 33 receives an electrical signal from the controller 20 (described later) and switches the hydraulic circuit.

[0076] The brake mechanism 33 then switches the hydraulic circuit to control the hydraulic pressure acting on the front and rear friction brakes 31. The level of hydraulic pressure corresponds to the level of braking force distributed by the friction brakes 31. In other words, when the hydraulic pressure is low, the braking force is lower compared to when the hydraulic pressure is high.

[0077] In order to determine the level of hydraulic pressure in the friction brake system 3, a brake fluid pressure sensor 57 is electrically connected to the controller 20 according to this embodiment (shown only in Figure 3A). This brake fluid pressure sensor 57 detects the hydraulic pressure in the friction brake system 3 and inputs a signal indicating the detection result to the controller 20.

[0078] Furthermore, the controller 20 according to this embodiment performs cooperative regenerative control (first regenerative control) during vehicle deceleration when the brake pedal 19 is operated, which uses the regenerative braking torque of the motor 5 to supply a portion of the braking force requested by the driver. In this case, the hydraulic pressure of the friction brake 31 is reduced by the amount of the regenerative braking torque of the motor 5.

[0079] This coordinated regenerative control is configured to perform braking through the coordinated distribution of braking force by the friction brake system 3 and the regenerative action of the motor 5 (more specifically, the application of regenerative braking torque to the rear wheels 2R by causing the motor 5 to perform a regenerative action).

[0080] Coordinated regenerative control can be performed with the K0 clutch 6 disengaged. By performing coordinated regenerative control with the K0 clutch 6 disengaged, the motor 5 can perform regenerative operation without being hindered by engine braking. This allows for a greater amount of power generation by the motor 5.

[0081] Furthermore, in this embodiment, if a restart of the engine 4 is requested during cooperative regenerative control, the controller 20 can perform restart control consisting of multiple processes. The general processes performed by the controller 20, including the processes related to this restart control, will be described below.

[0082] (General processing) Figure 4 is a flowchart illustrating the process related to engine 4. Figure 5 is a flowchart illustrating the process related to motor 5 and brake (friction brake system 3). The control processes in Figure 4 and Figure 5 are not performed one after the other in sequence, but are configured to proceed almost simultaneously.

[0083] First, in step S11 of Figure 4, the controller 20 reads inputs from various sensors and switches. In the following step S12, the controller 20 determines whether the driver is pressing the accelerator pedal 18. This determination is made based on the signal from the accelerator pedal position sensor 54.

[0084] If the decision in step S12 is Yes, that is, if the driver is pressing the accelerator pedal 18, the controller 20 proceeds to step S13 of the control process. If the decision in step S12 is No, that is, if the driver is not pressing the accelerator pedal 18, the controller 20 proceeds to step S16 of the control process.

[0085] Note that the content of step S11 is the same as step S31 in Figure 5. The content of step S12 is the same as step S32 in Figure 5. For the sake of explanation, steps S11 and S31, and steps S12 and S32 are shown on separate flowcharts, but each step is not performed as an independent process, but rather as a common process for the engine 4, motor 5, and friction brake system 3.

[0086] For example, if the decision in step S32 is Yes, that is, if the driver is pressing the accelerator pedal 18, the controller 20 proceeds to step S33. If the decision in step S32 is No, that is, if the driver is not pressing the accelerator pedal 18, the controller 20 proceeds to step S36.

[0087] (Processing when acceleration is requested) The processes in steps S13 to S15 in Figure 4 and steps S31 to S33 in Figure 5 are mainly performed when the vehicle 1 requests acceleration. That is, when the process proceeds to steps S13 and S23, the controller 20 determines that the vehicle 1 should accelerate and executes control corresponding to that determination.

[0088] Specifically, in step S13 of Figure 4, the controller 20 engages both the K0 clutch 6 and the K1 clutch 8d. This engagement is performed by the controller 20 controlling the first hydraulic circuit 13 and the second hydraulic circuit 8e. If both the K0 clutch 6 and the K1 clutch 8d are already engaged, the controller 20 maintains that engagement.

[0089] In step S14, the controller 20 determines the total driving force to be exerted by the engine 4 and motor 5 based on the amount the accelerator pedal 18 is pressed and the current vehicle speed. This determination is made based on the signal from the accelerator opening sensor 54 and the signal from the vehicle speed sensor 51. Furthermore, the controller 20 determines the driving force that the engine 4 should exert based on the driving force determined as described above.

[0090] Subsequently, in step S15, the controller 20 determines the fuel injection amount and other parameters to achieve the driving force determined in step S14, and controls the engine 4 based on the various parameters determined in this way.

[0091] In contrast, the content of step S33 in Figure 5 is the same as that of step S13 described above. For the sake of explanation, steps S33 and S13 are shown on separate flowcharts, but each step is not performed as an independent process, but rather as a common process for the engine 4, motor 5, and friction brake system 3.

[0092] Subsequently, in step S34, following step S33, the controller 20 determines the total driving force to be exerted by the engine 4 and motor 5 based on the amount the accelerator pedal 18 is pressed and the current vehicle speed. This process is the same as the process in step S14 described above. Furthermore, the controller 20 determines the driving force to be exerted by the motor 5 based on the driving force determined as described above.

[0093] Subsequently, in step S35, the controller 20 determines the control parameters of the motor 5 to realize the driving force determined in step S34, and then operates the motor 5 based on the various parameters determined in this way.

[0094] (Processing when no acceleration is requested and the brake pedal is not operated) The processes in steps S16 to S25 in Figure 4 and steps S36 to S45 in Figure 5 are mainly performed when the vehicle 1 requests non-acceleration (especially when the vehicle is decelerating). If the process proceeds to steps S16 and S36, the controller 20 executes processing according to the operation status of the brake pedal 19, etc. The following explanation will focus on the processing performed when the brake pedal 19 is not pressed (when the brake pedal 19 is not operated) and a non-acceleration request is made.

[0095] First, the control process related to engine 4 proceeds to step S16 in Figure 4 when there is a non-acceleration request and the accelerator pedal 18 is not pressed. In step S16, the controller 20 determines whether or not the air conditioner 72 is off. This determination is made based on the signal from the A / C switch 71.

[0096] If the determination in step S16 is Yes, that is, if the air conditioner 72 is in the off state (the air conditioner 72 is not running), the controller 20 proceeds to step S17 of the control process. If the determination in step S16 is No, that is, if the air conditioner 72 is in the on state, the controller 20 proceeds to step S18 of the control process.

[0097] Furthermore, in step S17, which follows step S16, the controller 20 determines whether the driver is pressing the brake pedal 19. This determination is made based on the signal from the brake pedal sensor 53. If the determination in step S17 is Yes, that is, if the driver is pressing the brake pedal 19, the process proceeds to step S22. If the determination in step S17 is No, that is, if the driver is not pressing the brake pedal 19, the process proceeds to step S18.

[0098] If the vehicle proceeds to step S22, fuel injection is stopped on the engine 4 side, while coordinated regenerative control is performed on the motor 5 and friction brake system 3 side, depending on the vehicle speed. This control is performed with the K0 clutch 6 disengaged, depending on the operation status of the A / C switch 71.

[0099] On the other hand, if the process proceeds to step S18 instead of step S22, the vehicle 1 will decelerate more slowly than when the brake pedal 19 is operated. In this case, the controller 20 will perform processing that takes into account the suppression of engine stall, etc.

[0100] Specifically, in step S18, the controller 20 determines whether the engine speed (Ne) is greater than a predetermined first threshold (N1) (Ne>N1?). This determination is made based on the signal from the engine speed sensor 55.

[0101] If the decision in step S18 is Yes, that is, if the engine speed is greater than the first threshold, the controller 20 proceeds to step S19 of the control process. If the process proceeds to step S19, the controller 20 stops fuel injection to the engine 4 and then proceeds to step S20 of the control process.

[0102] On the other hand, when the determination in step S18 is No, that is, when the engine speed is below the first threshold value, the controller 20 skips step S19 in the control process and advances to step S20. In this case, the controller 20 continues the fuel injection of the engine 4. Thereby, it is possible to suppress engine stalling associated with deceleration.

[0103] In step S20, the controller 20 determines whether the motor speed (Nm) is less than a predetermined second threshold value (N2) (Nm < N2?). This determination is made based on the signal of the motor rotation sensor 56.

[0104] Here, when the determination in step S20 is Yes, that is, when the motor speed is less than the second threshold value, the controller 20 advances the control process to step S21. When advancing to step S21, if the fuel injection was stopped in step S19 described above, the controller 20 also resumes the fuel injection. As also shown in step S40 of FIG. 5, the controller 20 slips the K1 clutch 8d in conjunction with the resumption of the fuel injection. By controlling in this way, it is possible to suppress engine stalling.

[0105] On the other hand, when the determination in step S20 is No, that is, when the motor speed is greater than or equal to the second threshold value, the controller 20 skips step S21 and returns the control process.

[0106] In contrast, the control process related to the motor 5 and the friction brake system 3 proceeds to step S36 of FIG. 5 when there is no acceleration request. In this step S36, the controller 20 determines whether the vehicle speed (Vv) of the automobile 1 is greater than a predetermined first speed (V1) (Vv < V1?). This determination is made based on the signal of the vehicle speed sensor 51.

[0107] If the determination in step S36 is Yes, that is, if the vehicle speed is greater than the first speed, the controller 20 proceeds to the later stage of step S35. In this case, the control process returns without any special processing.

[0108] On the other hand, if the determination in step S36 is No, that is, if the driver is not pressing the brake pedal 19, the process proceeds to step S37. In step S37, the controller 20 determines whether or not the driver is pressing the brake pedal 19. This determination is made based on the signal from the brake pedal sensor 53.

[0109] If the decision in step S37 is Yes, that is, if the driver is pressing the brake pedal 19, the process proceeds to step S41. If the decision in step S37 is No, that is, if the driver is not pressing the brake pedal 19, the process proceeds to step S38.

[0110] If the process proceeds to step S41, coordinated regenerative control is performed on the motor 5 and friction brake system 3 side, while fuel injection is stopped on the engine 4 side according to the operation status of the A / C switch 71. These controls can be performed with the K0 clutch 6 disengaged.

[0111] On the other hand, if the process proceeds to step S38 instead of step S42, the vehicle 1 will decelerate more slowly than when the brake pedal 19 is operated. In this case, the controller 20 will perform processing that takes into account the suppression of engine stall, etc.

[0112] Specifically, in step S38, which is performed during deceleration when the driver is not pressing the brake pedal 19, the controller 20 starts a second regenerative control that performs regenerative braking equivalent to engine braking.

[0113] This second regenerative control is regenerative control performed during deceleration of the vehicle 1 when the friction brake system 3 is not applying braking force to the front wheels 2F and the rear wheels 2R, and is so-called "motor regeneration" that applies regenerative braking torque to the rear wheels 2R by causing the motor 5 to perform a regenerative operation.

[0114] After starting the second regenerative control in step S38, the controller 20 monitors the motor speed. Specifically, in step S39 following step S38, the controller 20 determines whether the motor speed (Nm) is less than a predetermined second threshold value (N2) (Nm < N2?). This determination is made based on the signal from the motor rotation sensor 56.

[0115] Here, if the determination in step S39 is Yes, that is, if the motor speed is less than the second threshold value, the controller 20 advances the control process to step 40. When advancing to step S40, the controller 20 slips the K1 clutch 8d (K1 slip). In addition, the controller 20 terminates the second regenerative control (motor regeneration) started in step S38 described above. By controlling in this way, engine stall is avoided.

[0116] On the other hand, if the determination in step S39 is No, that is, if the motor speed is greater than or equal to the second threshold value, the controller 20 skips step S40 and returns the control process.

[0117] (Processing when there is no acceleration request and the brake pedal is operated) When the brake pedal 19 is depressed (during operation of the brake pedal 19) and there is no acceleration request, the control process advances to step S22 in FIG. 4 and step S41 in FIG. 5. The processing in these cases will be described below.

[0118] First, in step S22, which corresponds to the control process of engine 4, the controller 20 stops fuel injection to engine 4. As a result, the engine speed reaches zero. In parallel with stopping fuel injection, the controller 20 performs the above-mentioned coordinated regenerative control via motor 5 and friction brake system 3, with the K0 clutch 6 released as needed.

[0119] Subsequently, the controller 20 stops fuel injection from the engine 4 while continuing the coordinated regenerative control by the motor 5 and the friction brake system 3.

[0120] Subsequently, in step S23, which follows step S22, the controller 20 determines whether or not it is requested to start the engine 4 during the cooperative regenerative control.

[0121] Specifically, the controller 20 according to this embodiment determines that engine 4 needs to be started when the steering angle exceeds a predetermined value (α) during cooperative regenerative control, or when the A / C switch 71 is turned on during cooperative regenerative control. The former determination is made based on the signal from the steering angle sensor 52.

[0122] If the decision in step S23 is Yes, the controller 20 proceeds to step S24. In this case, the control processes for the motor 5 and the friction brake system 3 also proceed to step S45 in Figure 5, which corresponds to step S24.

[0123] In step S24, the controller 20 performs a coordinated restart control involving the engine 4, motor 5, and friction brake system 3. Once this restart control is complete, the controller 20 returns the control process.

[0124] Conversely, if the decision in step S23 is No, the control process skips step S24 and returns. In this case, restart control is not performed.

[0125] Meanwhile, in step S41, which corresponds to the control process of the motor 5 and the friction brake system 3, the controller 20 determines whether the air conditioner 72 is in the off state. This determination is made based on whether the A / C switch 71 has been turned on, and consequently on the signal from the A / C switch 71.

[0126] If the determination in step S41 is Yes, that is, if the air conditioner 72 is in the off state (the air conditioner 72 is not operating), the controller 20 proceeds to step S42 of the control process. In step S42, the controller 20 releases the K0 clutch 6. This interrupts the power transmission between the engine 4 and the motor 5. Once the processing in step S42 is complete, the controller 20 proceeds to step S43 of the control process to start cooperative regenerative control.

[0127] On the other hand, if the determination in step S41 is No, that is, if the air conditioner 72 is in the ON state (when the A / C switch 71 has been turned ON), the control process skips step S42 and proceeds to step S43. In other words, when the brake pedal 19 is pressed and the A / C switch 71 has been turned ON, the controller 20 starts cooperative regenerative control without releasing the K0 clutch 6.

[0128] In step S43, the controller 20 performs coordinated regenerative control, which uses the regenerative braking torque of the motor 5 to supply a portion of the braking force requested by the driver. The hydraulic pressure of the friction brake 31 is reduced by the amount of the regenerative braking torque of the motor 5. As a result of the reduction in the hydraulic pressure of the friction brake 31, the braking force caused by the friction brake system 3 decreases.

[0129] Subsequently, in step S44, which follows step S43, the controller 20 determines whether or not it is requested to start the engine 4 during the cooperative regenerative control.

[0130] Note that the content of step S44 is the same as step S23 in Figure 4. For the sake of explanation, steps S44 and S23 are shown on separate flowcharts, but each step is not performed as an independent process, but rather as a common process for the engine 4, motor 5, and friction brake system 3.

[0131] If the decision in step S44 is Yes, the controller 20 proceeds to step S45 to execute restart control. Once this restart control is complete, the controller 20 returns to the control process.

[0132] Conversely, if the decision in step S44 is No, the control process skips step S45 and returns. In this case, restart control is not performed.

[0133] (Restart control) Figure 6 is a flowchart illustrating the process related to restart control. First, in step S51 of Figure 6, the controller 20 performs a first process that transitions from braking by cooperative regenerative control to braking by the friction brake system 3 alone. The controller 20 switches from braking by cooperative regenerative control to braking by the friction brake 31 alone. When this switch is made, the required braking force, including the portion that was previously supplied by the regenerative braking torque of the motor 5, is entirely supplied by the friction brake system 3.

[0134] Specifically, in step S51, the controller 20 increases the braking force of the friction brake 31 to compensate for the amount that was previously covered by the regenerative braking torque of the motor 5. The controller 20 increases the hydraulic pressure of the friction brake 31 by the amount of the regenerative braking torque of the motor 5. The increased hydraulic pressure of the friction brake 31 increases the braking force attributable to the friction brake system 3.

[0135] However, the hydraulic pressure of the friction brake 31 is not adjusted instantaneously. Therefore, in step S52 following step S51, the controller 20 determines whether the transition to braking using only the friction brake system 3 has been completed. This determination is made based on the signal from the brake hydraulic pressure sensor 57.

[0136] In the following steps S53 to S55, after the transition to braking by the friction brake system 3 alone is complete, the controller 20 performs a second process to increase the engine speed by starting to engage the K0 clutch 6 and causing the motor 5 to perform either a powering or regenerative operation.

[0137] Specifically, in step S53, the controller 20 determines whether the K0 clutch 6 is open or not. If the determination is Yes, the controller 20 proceeds to step S55 via step S54. On the other hand, if the determination in step S53 is No, the controller 20 skips step S54 and proceeds to step S55.

[0138] In step S54, the controller 20 activates the first hydraulic circuit 13 to begin engaging the K0 clutch 6. The K0 clutch 6 will be engaged while slipping.

[0139] As the K0 clutch 6 is gradually engaged via step S54, or as in the case where step S54 is skipped, the K0 clutch 6 is already engaged, causing the crankshaft 4a to be rotationally driven by the motor 5. At this time, the engine speed may be increased by transmitting the regenerative action of the motor 5 to the crankshaft 4a, or by transmitting the accelerating action of the motor 5 to the crankshaft 4a.

[0140] Note that the connection to the engine 4 creates a rotational resistance for the motor 5. Therefore, when the K0 clutch 6 is engaged and the engine speed starts to increase, the motor speed, and thus the vehicle speed, will gradually decrease. Therefore, as the engine speed increases, the motor 5 may be made to perform a power running operation to gradually increase the output torque of the motor 5.

[0141] As a result, as shown in step S55 following step S54, engine start (starting of the engine speed) by transmitting the rotation of the motor 5 to the engine 4 is started. Note that at step S55, the motor 5 is used for starting control to increase the engine speed instead of drive force control for outputting the driving force of the automobile 1.

[0142] Thereafter, after the engagement of the K0 clutch 6 is started, the controller 20 executes a third process of restarting the operation of the engine 4 at a timing after the engine speed has increased until it matches the motor speed.

[0143] Specifically, in step S56 following step S55, the controller 20 determines whether the engine speed has matched the motor speed (Ne = Nm?). This determination is made based on the signals from the engine rotation sensor 55 and the motor rotation sensor 56.

[0144] If the determination in step S56 is Yes, the controller 20 advances the control process to step S59. In step S59, the controller 20 determines that the starting of the engine 4 has been completed.

[0145] On the other hand, if the determination in step S56 is No, the controller 20 advances the control process to step S57. In step S57, the controller 20 determines whether the motor speed has fallen below a predetermined second threshold value (N2) (Nm < N2?). This determination is made based on the signal from the motor rotation sensor 56.

[0146] If the determination in step S57 is No, the controller 20 proceeds with the control process by skipping the following step S58 and returning to step S56 described above. In other words, the determination in step S57 is repeated until the engine speed matches the motor speed.

[0147] On the other hand, if the decision in step S57 is Yes, the controller 20 proceeds to step S58 of the control process. In step S58, the controller 20 causes the K1 clutch 8d to slip (K1 slip) in order to interrupt or reduce the power transmission between the axle and the motor 5.

[0148] Thus, the controller 20 is configured to slip the K1 clutch 8d when the output speed of the motor 5 falls below a second threshold, which is a predetermined rotational speed, after the K0 clutch 6 has been engaged in the second process.

[0149] If the determination in step S56 is Yes, then in the subsequent step S59, it is determined that the engine 4 has finished starting, as described above. Therefore, in the following step S60, the controller 20 restarts fuel injection to the engine 4. This restarts the operation of the engine 4.

[0150] In step S60, the engine 4 and motor 5 work in coordination to output the driving force for the vehicle 1. At this time, the controller 20 controls the engine 4 and motor 5 to achieve deceleration corresponding to the amount the brake pedal 19 is pressed. However, excessive or prolonged deceleration may lead to engine stall.

[0151] Therefore, in step S61 following step S60, the controller 20 executes the idle control of the automobile 1. Specifically, in this step S61, the controller 20 determines whether the engine speed and the motor speed have fallen below a predetermined idle speed (for example, the second threshold value) (Ne < N2? or Nm < N2?). If this determination is Yes, the K1 clutch 8d is released or slipped.

[0152] In addition to releasing or slipping the K1 clutch 8d, the controller 20 further adjusts the output torques of the engine 4 and the motor 5 to maintain the engine speed or the motor speed at or above the predetermined speed. At that time, the controller 20 may increase the fuel injection amount of the engine 4. Further, in addition to increasing the fuel injection amount, the idle control may be assisted by strengthening the power running operation of the motor 5 or weakening the regenerative operation of the motor 5.

[0153] In this way, in the third process, after the output rotation speed of the engine 4 is made to match the output rotation speed of the motor 5 (for example, after the engine 4 is restarted), when the output rotation speeds of the engine 4 and the motor 5 drop below the predetermined idle speed, the K1 clutch 8d is released or slipped, and the engine 4 is idly controlled so that the output rotation speeds of the engine 4 and the motor 5 rise above the idle speed.

[0154] (Control Example) Next, the first process, the second process, and the third process will be described while referring to the time chart of FIG. 7. This time chart includes a cooperative regeneration flag, a steering angle flag, a restart flag, the operation status of the accelerator pedal 18, the operation status of the brake pedal 19, the change in vehicle speed, the change in motor speed, and the change in engine speed.

[0155] Here, the cooperative regeneration flag is set to 1 when it is determined that cooperative regeneration control should be performed. The steering angle flag is set to 1 when a signal from the steering angle sensor is detected (when the steering wheel 110 is operated). The restart flag is set to 1 when it is determined that restart control should be performed. The operation status of the accelerator pedal 18 is ON when the accelerator pedal 18 is operated and OFF when it is not operated. The operation status of the accelerator pedal 18 is ON when the brake pedal 19 is operated and OFF when it is not operated.

[0156] First, let's assume that the brake pedal 19 is pressed at time t0 when the accelerator pedal 18 is not being operated (i.e., when the vehicle 1 is decelerating). In this case, since the engine 4 is stopped (fuel injection is stopped) at times prior to time t0, the engine speed is zero.

[0157] Then, because the engine 4 is stopped and the brake pedal 19 is pressed, the vehicle speed decreases relatively rapidly. In this case, the cooperative regeneration flag becomes 1, and cooperative regeneration control is started. The full required braking force is achieved through the cooperation of the motor 5 and the friction brake system 3, and at the same time, power is generated by the motor 5.

[0158] Subsequently, at time t1, the driver operates the steering wheel 110. This operation is judged to have requested a restart of the engine 4. Based on this judgment, the steering angle flag becomes 1, and braking is switched from coordinated braking by the motor 5 and the friction brake system 3 to braking by the friction brake system 3 alone (first process).

[0159] Subsequently, it is assumed that the braking switch is completed at time t2. In response, the restart flag is set to 1. With the restart flag set to 1, the K0 clutch 6 begins to engage, and receiving power from the motor 5, the engine speed begins to increase (second process). As the engine speed increases, the motor speed continues to decrease.

[0160] Subsequently, when the motor speed falls below the second threshold at time t3, the K1 clutch 8d slips. By slipping the K1 clutch 8d, the motor speed begins to increase and is maintained above the second threshold.

[0161] As is clear from the sequence of events between time t2 and time t3, in this embodiment, the slip of the K1 clutch 8d occurs after the switch to braking by the friction brake system 3 alone has been completed.

[0162] If the timing of slipping the K1 clutch 8d and the timing of switching the braking are not correlated, as in conventionally known configurations, there is a possibility that the K1 clutch 8d will slip before the braking switch is complete. In this case, the regenerative operation will be performed with power transmission between the motor 5 and the rear wheel 2R suppressed, so the output torque (regenerative braking torque) of the motor 5 may not be sufficiently transmitted to the rear wheel 2R, potentially causing a loss of G-force.

[0163] On the other hand, in this embodiment, the K1 clutch 8d is made to slip after the braking switchover is completed. As a result, the K1 clutch 8d starts to slip when the application of regenerative braking torque has finished (for example, when the regenerative braking torque has been reduced to approximately zero). This makes it possible to suppress the occurrence of G-force loss.

[0164] Subsequently, when the engine speed and motor speed match at time t4, the controller 20 completes the restart of the engine 4. Then, the controller 20 restarts the operation of the engine 4 by restarting fuel injection (third process).

[0165] (Regarding the coordination between brake switching and engine restart) As described above, according to this embodiment, while the automobile 1 is decelerating with the friction brake system 3 distributing braking force to the rear wheels 2R, the motor 5 performs regenerative operation. This control is coordinated regenerative control by the friction brake system 3 and the motor 5. Coordinated regenerative control increases the regenerative energy stored in the high-voltage battery 9. The regenerative braking torque from the motor 5 is applied to the rear wheels 2R, which are drive wheels. The friction brake system 3 distributes braking force to the rear wheels 2R, taking into account the regenerative braking torque applied to the rear wheels 2R. As a result, the braking acting on the automobile 1 becomes braking that corresponds to the driver's operation of the brake pedal 19. The controller 20 controls the distribution of braking force so that the desired braking (braking that corresponds to the operation of the brake pedal 19) is achieved by the regenerative braking torque and braking force.

[0166] Here, as illustrated in the sequence of steps S52 and S55 in Figure 6, when the controller 20 is requested to start the engine 4 during cooperative regenerative control, it increases the output speed of the engine 4 after the transition from braking by cooperative regenerative control to braking by the friction brake system 3 alone is completed.

[0167] Therefore, as illustrated at time t2 in Figure 7, by the time the engine speed adjustment is initiated, the braking switch has already been completed. As a result, the influence of the output speed adjustment status on the cooperative regenerative control and the switching of braking from that cooperative regenerative control can be suppressed.

[0168] Furthermore, as illustrated in step S61 of Figure 6, the engine speed may continue to be controlled by idle control, etc., even after adjustment. Therefore, by starting the engine 4 after the braking is switched, it is possible to separate the processing related to the output speed, such as idle control, from the processing related to the braking switch. This makes it possible to suppress the influence of processing such as idle control on the braking switch.

[0169] Furthermore, as illustrated in steps S57 and S58 of Figure 6, the controller 20 slips the K1 clutch 8d when predetermined conditions are met. By slipping the K1 clutch 8d, the rotational resistance of the motor 5 can be reduced. This makes it possible to suppress a decrease in the output speed of the motor 5.

[0170] In this case, if there is no correlation between the timing of slipping the K1 clutch 8d and the timing of switching to braking using only the friction brake system 3, as in conventionally known configurations (for example, if the two processes start simultaneously), there is a possibility that the K1 clutch 8d will slip before the braking switch is completed.

[0171] In this case, since regenerative braking is performed with power transmission between motor 5 and rear wheel 2R suppressed, the regenerative braking torque applied by motor 5 may not be sufficiently transmitted to rear wheel 2R, potentially causing a loss of G-force.

[0172] On the other hand, in this embodiment, as illustrated by the sequence of steps S52 and S58 in Figure 6, and the sequence of times t2 and t3 in Figure 7, the K1 clutch 8d is made to slip after the braking switchover is completed. As a result, the K1 clutch 8d starts to slip when the application of regenerative braking torque has finished (for example, when the regenerative braking torque has been reduced to approximately zero). This makes it possible to suppress the occurrence of G-force loss.

[0173] Furthermore, by performing idle control as illustrated in step S61 of Figure 6, the output speeds of the engine 4 and motor 5 can be maintained above the idle speed after the engine 4 is restarted. This allows the vehicle 1 to accelerate smoothly when an acceleration request is made to the vehicle, such as when the brake pedal 19 is pressed down and the accelerator pedal 18 is pressed down.

[0174] Furthermore, as illustrated in step S23 of Figure 4 and step S44 of Figure 5, the controller 20 executes the first, second, and third processes described above when the steering wheel 110 is operated during deceleration when the brake pedal 19 is pressed (i.e., while cooperative regenerative control is being performed). This allows the engine 4 to be restarted smoothly without causing problems such as loss of G-force when, for example, the vehicle 1 enters a corner while the brake pedal 19 is pressed. This makes it possible to achieve so-called slow-in, fast-out more smoothly than in conventional hybrid vehicles. This improves the operability of the hybrid vehicle.

[0175] Furthermore, as illustrated in step S23 of Figure 4 and step S44 of Figure 5, the controller 20 executes the first, second, and third processes described above when the A / C switch 71 is operated during deceleration when the brake pedal 19 is pressed (i.e., while cooperative regenerative control is being performed). This allows the engine 4 to be restarted smoothly without causing problems such as loss of G-force when, for example, the air conditioner 72 is desired to be driven when the brake pedal 19 is pressed. This suppresses the shock when the engine is restarted, thereby improving the ride comfort of the hybrid vehicle. [Explanation of symbols]

[0176] 1. Automobile (vehicle, hybrid vehicle) 17. Drive shaft (axle) 19 Brake pedal 20 Controller (control means) 2R Rear wheels (drive wheels) 3. Friction Brake System 4 engines 5 Motors 6 K0 Clutch (First Clutch) 8 Automatic transmission 8d K1 clutch (second clutch) 8e Second Hydraulic Circuit 13. First Hydraulic Circuit 52 Steering angle sensor 55 Engine rotation sensor 56 Motor rotation sensor 71 A / C switch (air conditioner switch) 72 Air conditioner 110 Steering Wheel

Claims

1. The engine that generates the driving force for the vehicle, A motor capable of performing both powering and regenerative braking operations, A first clutch interposed between the engine and the motor, which can be switched between a connected state in which the engine and the motor are fastened together and a disconnected state in which the fastening is released, A control device for a hybrid vehicle comprising the motor and an axle interposed between the drive wheels of the vehicle, A second clutch interposed between the motor and the axle, which can be switched between a connected state in which the motor and the axle are fastened together and a disconnected state in which the fastening is released, A hydraulic friction brake system that distributes braking force to the drive wheels in response to the driver's operation of the brake pedal, The system includes a control means capable of performing coordinated regenerative control, while the first clutch is disengaged, which involves braking through the coordinated distribution of the braking force by the friction brake system and the application of regenerative braking torque to the drive wheels by causing the motor to perform a regenerative operation, during vehicle deceleration when the brake pedal is operated. When the engine is requested to start during the cooperative regenerative control, the control means shall A first process that transitions from braking by the aforementioned coordinated regenerative control to braking by the aforementioned friction brake system alone, After the transition to braking by the friction brake system alone is completed, a second process is performed to increase the engine's output speed by initiating the engagement of the first clutch and causing the motor to perform the traction operation or the regenerative operation, After the engagement of the first clutch is initiated, a third process is performed to restart the engine at a timing after the engine's output speed has increased to match the motor's output speed, The second clutch is engaged when the coordinated regenerative control is executed. The control means, after the engagement of the first clutch in the second process, causes the motor's output rotational speed to drop below a predetermined rotational speed, to cause the second clutch to slip. A control device for a hybrid vehicle characterized by the following features.

2. In the control device for a hybrid vehicle described in claim 1, In the third process, the control means, after matching the output speed of the engine to the output speed of the motor, if the output speeds of the engine and the motor fall below a predetermined idle speed, disengages or slips the second clutch and controls the engine to raise the output speed to above the idle speed. A control device for a hybrid vehicle characterized by the following features.

3. In the control device for a hybrid vehicle described in claim 1, The control means determines that an engine start is required when the steering angle exceeds a predetermined value during the cooperative regenerative control. A control device for a hybrid vehicle characterized by the following features.

4. In the control device for a hybrid vehicle described in claim 1, The control means determines that the engine has been requested to start when the air conditioner switch is turned ON during the cooperative regenerative control. A control device for a hybrid vehicle characterized by the following features.

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