HYBRID VEHICLE

Abstract

Hybrid vehicle (1) in which a front wheel (6) and a rear wheel (7) are driven by power from one or both of an internal combustion engine (2) and an electric motor (3), the hybrid vehicle (1) comprising: a drive control unit (10) capable of performing control for the termination of a blockage by increasing the drive torque of the hybrid vehicle (1) so that the hybrid vehicle (1) terminates a blocked state when a predetermined actuation is performed, wherein the drive control unit (10) performs an electric motor torque reduction control in which an electric motor torque corresponding to a torque of the electric motor (3) is reduced when it is detected that the hybrid vehicle (1) has ended the locked state and the front wheel (6) has spun during the control for ending a lock, wherein the drive control unit (10) during electric motor torque reduction control controls the electric motor (3) such that the electric motor torque becomes zero when a portion of the electric motor torque occupying the drive torque output by the control for terminating a blockage is equal to or greater than a predetermined value, and controls the electric motor (3) in a regenerative drive mode when the portion of the electric motor torque occupying the drive torque output by the control for terminating a blockage is less than the predetermined value.

Description

[Technical field]

[0001] This invention relates to a hybrid vehicle. [Background of the invention]

[0002] JP 2006-230130 A discloses a four-wheel drive vehicle of the electric motor type which performs motor drive control in a locked state so as to cancel the locked state when it is determined that the locked state continues for a predetermined period of time or longer.

[0003] DE 10 2009 001 293 A1 discloses a method for operating a drive train of a motor vehicle, wherein the drive train comprises a drive unit, an accelerator pedal, and a brake pedal. When the accelerator pedal and the brake pedal are not actuated, the drive train is operated in a speed-controlled creep mode such that a speed setpoint is compared with an actual speed value, and a creep torque is generated based on the deviation between the two, so that the actual speed value approaches the speed setpoint. When creep mode is started, the speed setpoint is specified such that it is increased from an initial value to a final value, with the generated creep torque being limited to a maximum value.

[0004] From DE 10 2007 042 128 A1 a driving assistance device for a motor vehicle is known, which has a speed measuring device, a torque measuring device and a torque control device, wherein the driving assistance device is limited to a speed range between 0 and 10 km / h and the torque control device, in a first operating mode, limits the speed of the torque change of the torque transmitted to the drive wheels to a certain predeterminable value. [Summary of the invention][Problem to be solved by the invention]

[0005] Incidentally, there is a case where a vehicle cannot smoothly shift to a driving state when the vehicle exits the locked state depending on a road surface condition. For example, in a condition where a vehicle wheel is locked due to an obstacle, the front wheel will overcome the obstacle when it exits the locked state. For this reason, if the torque is too high, there is a concern that the front wheel may slip and spin. In such a case, in a four-wheel drive vehicle, the front wheel has an increased possibility of slipping and the vehicle's posture will be unstable because a large amount of driving force is distributed to the rear wheel.

[0006] An object of this invention is to provide a hybrid vehicle that can smoothly switch to a driving state when a locked state is released. [Means of solving the problem]

[0007] According to aspects of this invention, there is provided a hybrid vehicle in which a front wheel and a rear wheel are driven by the power of at least one of an internal combustion engine and an electric motor, the hybrid vehicle including: a drive control unit capable of performing lock-up release control in which a drive torque of the hybrid vehicle is increased so that the hybrid vehicle releases a locked state when a predetermined operation is performed, wherein the drive control unit performs motor torque reduction control in which a motor torque corresponding to a torque of the electric motor is reduced when it is detected that the hybrid vehicle has released the locked state and the front wheel has slipped during the lock-up release control.The drive control unit controls the electric motor during the electric motor torque reduction control so that the electric motor torque becomes zero when a proportion of the electric motor torque occupying the drive torque output by the lock-up release control is equal to or greater than a predetermined value, and controls the electric motor in a regenerative drive mode when the proportion of the electric motor torque occupying the drive torque output by the lock-up release control is less than the predetermined value. [Effect of the invention]

[0008] This invention provides a hybrid vehicle that can smoothly switch to a driving state when exiting a locked state. [Brief description of the characters] [ Fig. 1] Fig. 1 is a schematic diagram of a configuration of a hybrid vehicle according to an embodiment of this invention. [ Fig. 2] Fig. 2 is a block diagram illustrating a configuration of various control units mounted on the hybrid vehicle according to an embodiment of this invention. [ Fig. 3] Fig. 3 is a timing chart illustrating a transition of an electric motor torque and an engine torque at the time of performing a lock-up cancellation control in the hybrid vehicle according to an embodiment of this invention. [ Fig. 4] Fig. 4 is a flowchart illustrating a flow of a process for determining whether to perform lock-up termination control, which is performed by a hybrid control unit of the hybrid vehicle according to an embodiment of this invention. [ Fig. 5] Fig. 5 is a flowchart illustrating a flow of a process during the lock-up cancellation control performed by the hybrid control unit of the hybrid vehicle according to an embodiment of this invention. [ Fig. 6] Fig. 6 is a flowchart illustrating a flow of a process of electric motor torque reduction control executed in step S13 of Fig. 5 is carried out. [ Fig. 7] Fig. 7 is a schematic diagram of a configuration showing a modified example of the hybrid vehicle according to an embodiment of this invention. [Embodiment(s) of the invention]

[0009] A hybrid vehicle according to embodiments of this invention is a hybrid vehicle in which a front wheel and a rear wheel are driven by the power of at least one of an internal combustion engine and an electric motor, the hybrid vehicle including: a drive control unit capable of performing lock-up release control in which a drive torque of the hybrid vehicle is increased so that the hybrid vehicle releases the locked state when a predetermined operation is performed, wherein the drive control unit performs motor torque reduction control in which a motor torque corresponding to a torque of the electric motor is reduced when it is detected that the hybrid vehicle has released the locked state and the front wheel has slipped during the lock-up release control.During the motor torque reduction control, the drive control unit controls the electric motor so that the electric motor torque becomes zero when a proportion of the electric motor torque occupies the drive torque output by the lock-up release control is equal to or greater than a predetermined value, and controls the electric motor in a regenerative drive mode when the proportion of the electric motor torque occupies the drive torque output by the lock-up release control is less than the predetermined value. Accordingly, the hybrid vehicle according to embodiments of this invention can smoothly shift to a driving state when it releases the locked state. [Embodiments]

[0010] Hereinafter, a hybrid vehicle according to embodiments of this invention will be described with reference to the drawings.

[0011] As in Fig. 1, a hybrid vehicle 1 includes an internal combustion engine 2, which is a driving power source, an electric motor generator 3 (referring to the Fig. 1 and Fig. 2 as “MG”), which is an electric motor, a gearbox 4 (referred to in Fig. 1 is referred to as “TM”), a transmission unit 5, a left and a right front wheel 6 and a left and a right rear wheel 7.

[0012] The hybrid vehicle 1 of this embodiment is a four-wheel drive vehicle in which the front wheel 6 and the rear wheel 7 are driven by the power of one of the internal combustion engine 2 and the electric motor generator 3.

[0013] The internal combustion engine 2 includes a plurality of cylinders and is configured to perform a series of four strokes, including an intake stroke, a compression stroke, a power stroke, and an exhaust stroke for each cylinder. An integrated starter generator 8 (ISG) is connected to the internal combustion engine 2.

[0014] The ISG 8 is connected to a crankshaft of the internal combustion engine 2 through a power transmission member such as a belt (not shown). The ISG 8 is connected to a battery 81 and is driven by the electric power supplied from the battery 81. The ISG 8 has a function of an electric motor that rotates the internal combustion engine 2 and a function of a generator that converts a rotational force supplied from the crankshaft into an electric power by driving the internal combustion engine 2. The battery 81 is configured, for example, as a lead storage battery.

[0015] The electric motor generator 3 is connected to a converter 30 (referring to Fig. 1 as "INV") is connected to a battery 31. The battery 31 is configured, for example, as a lithium-ion battery and is configured as a battery having a higher voltage than the battery 81.

[0016] The electric motor generator 3 is connected to the transmission unit 5 through a power transmission element (not shown). The electric motor generator 3 functions as an electric motor driven by the electric power supplied from the battery 31 and, conversely, as a generator that generates an electric power by the driving force supplied from the transmission unit 5. The electric motor generator 3 may, for example, be connected to an output shaft 41 of the transmission 4 instead of to the transmission unit 5.

[0017] The transmission 4 is configured as an automatic transmission that switches the rotation output from the engine 2 at a gear ratio corresponding to one of a plurality of gear stages and outputs the result to the transmission unit 5.

[0018] A clutch 9 is provided on a power transmission path between the engine 2 and the transmission 4. The clutch 9 is configured to switch between an engaged state, in which power is transmitted between the engine 2 and the clutch 4, and a disengaged state, in which power transmission is interrupted.

[0019] As the transmission 4 of this embodiment, an automated manual transmission (AMT) that automatically performs gear shifting and clutch operation can be used. The transmission 4 is not limited to the AMT; a multi-stage automatic transmission (AT), a continuously variable automatic transmission (CVD), or a manual transmission can also be used.

[0020] The gear ratios that can be adopted by the transmission 4 include, for example, a gear ratio for driving from a first speed to a fourth speed, and a reverse speed ratio. The number of driving gear ratios varies depending on the specifications of the hybrid vehicle 1 and is not limited to the first to fourth speed ratios.

[0021] The transmission unit 5 is used to distribute drive torque, which is a combined torque of the power of the engine 2 and the power of the motor generator 3, to the front wheel 6 and the rear wheel 7. This drive torque is a torque obtained by combining the power of the engine 2 transmitted through the transmission 4 and the power of the motor generator 3. According to this embodiment, the transmission unit 5 has a function of combining the output shaft of the transmission 4 and the output shaft of the motor generator 3 to provide the drive shaft for a power distribution device.In addition, a configuration may be used in which the power of the internal combustion engine 2 and the power of the electric motor generator 3 are combined on a single axle on the input side of the transmission unit and the combined torque is supplied to the transmission unit 5.

[0022] The drive torque distributed by the transmission unit 5 to the front wheel 6 is transmitted through a front differential 60 (to which Fig. 1 as “F-differential”) to the front wheel 6. The drive torque distributed by the transmission unit 5 to the rear wheel 7 is transmitted through a rear differential 70 (referred to in Fig. 1 is referred to as “R-differential”) to the rear wheel 7.

[0023] As in Fig. 2, the hybrid vehicle 1 includes a hybrid control unit 10, which is a drive control unit, and an inverter control unit 20, which controls an inverter 30.

[0024] Each of the hybrid control unit 10 and the inverter control unit 20 is configured as a computer unit including a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), a flash memory that stores backup data or the like, an input terminal, and an output terminal.

[0025] The ROM of the computer unit stores, together with various constants and various maps, a program that enables the computer unit to function as the hybrid control unit 10 and the inverter control unit 20, respectively.

[0026] That is, when the CPU executes a program stored in the ROM by using the RAM as a work area, such a computer unit functions respectively as the hybrid control unit 10 and the inverter control unit 20 according to this embodiment.

[0027] Various sensors are connected to the hybrid control unit 10, such as a battery sensor 11, an accelerator opening degree sensor 12, a vehicle wheel speed sensor 13, and a vehicle speed sensor and a termination switch 15.

[0028] The battery sensor 11 detects a charge / discharge current or voltage of the battery 31 and outputs it to the hybrid control unit 10. The hybrid control unit 10 calculates a charged state of the battery 31, i.e., a state of charge (SOC), based on the detection result input from the battery sensor 11.

[0029] Furthermore, if the hybrid vehicle 1 is provided with a battery management system (BMS) that manages the battery 31, the SOC may be calculated for the BMS, and the calculated SOC may be transmitted from the BMS to the hybrid control unit 10.

[0030] The accelerator opening degree sensor 12 detects the degree of depression of an accelerator pedal (not shown) by a driver and outputs it to the hybrid control unit 10. Four vehicle wheel speed sensors 13 are provided, each corresponding to the left and right front wheels 6 and the left and right rear wheels 7, and are configured to detect the rotational speeds of the left and right front wheels 6 and the rotational speeds of the left and right rear wheels 7, respectively, and output them to the hybrid control unit 10.

[0031] The vehicle speed sensor 14 is configured as an acceleration sensor and is configured to detect the acceleration of the hybrid vehicle 1 and output it to the hybrid control unit 10. The hybrid control unit 10 detects a vehicle speed, which is a speed of the hybrid vehicle 1, based on the acceleration information input from the vehicle speed sensor 14.

[0032] The termination switch 15 is provided on an instrument panel located near a driver's seat and is configured as a push-button switch operated by the driver. The termination switch 15 is a switch operated when the driver attempts to terminate the locked state when the hybrid vehicle 1 enters the locked state.

[0033] When the termination switch 15 is pressed by the driver according to a predetermined operation, a signal indicating that the termination switch 15 is pressed is output to the hybrid control unit 10.

[0034] The termination switch 15 is not limited to the push-button switch. For example, various configurations can be used, such as a lever type or a touch panel type, and the installation position is not limited to the instrument panel. (Control for ending a blockage)

[0035] When a signal indicating that the cancellation switch 15 is pressed is input to the hybrid control unit 10, lock-up cancellation control can be performed, in which the drive torque of the hybrid vehicle 1 is increased so that the hybrid vehicle 1 cancels the locked state. When the lock-up cancellation control is not performed, the drive torque of the hybrid vehicle 1 is generally set to an upper limit, and the upper limit is set to be smaller than a torque Tmax. Since the torque is not limited when the lock-up cancellation control is performed, the drive torque becomes larger compared to a state where the lock-up cancellation control is not performed.

[0036] The hybrid control unit 10 is configured to perform the lock-up cancellation control when the driver's depression of the accelerator pedal (not shown) is detected by the accelerator opening degree sensor 12 within a predetermined period of time after which the lock-up cancellation control can be performed.

[0037] The drive torque of the hybrid vehicle 1 is a total torque output from the internal combustion engine 2 and the electric motor generator 3 to the front wheel 6 and the rear wheel 7 through the transmission unit 5. Here, if the hybrid vehicle 1 is allowed to run only with the power of the internal combustion engine 2, the torque output from the internal combustion engine 2 to the front wheel 6 and the rear wheel 7 through the transmission unit 5 becomes the drive torque of the hybrid vehicle 1.

[0038] In contrast, when the hybrid vehicle 1 is allowed to run only with the power of the electric motor generator 3, the torque output from the electric motor generator 3 to the front wheel 6 and the rear wheel 7 through the transmission unit 5 becomes the drive torque of the hybrid vehicle 1.

[0039] When the SOC of the battery 31 exceeds a predetermined permission threshold, the hybrid control unit 10 is configured in the lock-up cancellation control to output the drive torque of the hybrid vehicle 1 by the motor torque corresponding to the torque of the motor generator 3 until a predetermined period of time elapses after the lock-up cancellation control is started.

[0040] In the lock-up cancellation control, the hybrid control unit 10 is configured to increase the engine torque corresponding to the torque of the engine 2 while decreasing the motor torque after the predetermined time has elapsed.

[0041] The predetermined time period is set in response to the SOC of the battery 31 or the electric motor temperature of the electric motor generator 3, and is set based on a map (not shown) that defines a relationship between the SOC, the electric motor temperature, and the predetermined time period. The map is obtained in advance through an experiment and stored in the ROM of the hybrid control unit 10. Furthermore, the predetermined time period is not limited to a variable set based on the map, but may be a constant obtained in advance through an experiment and stored in the ROM of the hybrid control unit 10.

[0042] Fig. 3 is a timing diagram illustrating a transition of the electric motor torque and the engine torque during the stall termination control when the SOC of the battery 31 exceeds a predetermined permit threshold. Fig. 3, a solid line indicates the electric motor torque, and a dash-dotted line indicates the engine torque.

[0043] In Fig. 3, the torque denoted by "Tmax" is a target drive torque of the hybrid vehicle 1, which increases during the lock-release control. The torque Tmax is a torque at which the hybrid vehicle 1 achieves maximum acceleration, and it is obtained in advance through an experiment and stored in the ROM of the hybrid control unit 10.

[0044] If the control for a termination of a blockage starts at time t0, as in Fig. As shown in Figure 3, only the electric motor torque increases to achieve the torque Tmax by the electric motor torque until a time t1, that is, until a period of time from time t0 to time t1 as the predetermined time period has elapsed. For this reason, a proportion occupied by the electric motor torque in the torque outputting the torque Tmax becomes 100 [%] until the time period from time t0 to time t1 has elapsed. During the time period from time t0 to time t1, the engine torque is 0.

[0045] Next, after time t1, at which the predetermined time period has elapsed, the engine torque increases while the motor torque decreases. After that, the torque Tmax is reached by the engine torque, and the motor torque becomes zero (hereinafter referred to as "0") at time t2. During a period from time t1 to time t2, the amount by which the torque Tmax cannot be reached by the engine torque alone is compensated by the motor torque. Thus, during the period from time t1 to time t2, the total torque of the motor torque and the engine torque is controlled to the torque Tmax.

[0046] After time t2, the torque Tmax is reached by the engine torque until the stall release control ends. Here, if the motor torque reduction control described later is performed even before the stall release control ends, the engine torque decreases due to the motor torque reduction control.

[0047] In the lock-out control, the hybrid control unit 10 is configured to output the drive torque to the hybrid vehicle 1 from the start of the lock-out control regardless of whether the predetermined time has elapsed when the SOC of the battery 31 is equal to or less than a predetermined permission threshold.

[0048] Here, the predetermined permission threshold is set to a value lower than a threshold for permitting normal EV driving or assist operation by the electric motor generator 3. Therefore, this means that the output of the electric motor torque by the electric motor generator 3 is permitted during the lock-up release control when the SOC of the battery 31 exceeds the predetermined permission threshold, even though the SOC is lower than a minimum threshold for permitting normal EV driving or assist operation. This is because the lock-up release control requires urgency. (Electric motor torque reduction control)

[0049] The hybrid control unit 10 is configured to perform the electric motor torque reduction control in which the electric motor torque is reduced when it is detected that the hybrid vehicle 1 has released the locked state and the front wheel 6 has slipped during the lock release control.

[0050] The electric motor torque reduction control is a control for inhibiting the slipping and spinning of the front wheel 6, for example, when the hybrid vehicle 1 whose front wheel is locked due to an obstacle has released the locked state during the lock release control.

[0051] When the engine torque is output during the electric motor torque reduction control, the hybrid control unit 10 is configured to control the engine 2 such that the engine torque becomes 0.

[0052] The hybrid control unit 10 has a function as a lock-up termination detector 101 that detects that the hybrid vehicle 1 has terminated the locked state when it is detected that the vehicle speed becomes higher than 0, that is, when a relation of vehicle speed > 0 is satisfied after lock-up of the hybrid vehicle 1 is determined or the lock-up termination control is started.

[0053] The hybrid control unit 10 can determine that the hybrid vehicle 1 is locked when the vehicle speed is 0 even though the rotation of the vehicle wheel of one of the front wheel 6 and the rear wheel 7 is detected by the vehicle wheel speed sensor 13.

[0054] Moreover, according to this embodiment, since the vehicle speed sensor 14 is configured as the acceleration sensor, it is possible to detect that the vehicle speed becomes greater than 0 even in a state where one of the front wheel 6 and the rear wheel 7 is slipped due to locking. Furthermore, according to this embodiment, the release of the locked state is detected when the relation of vehicle speed > 0 is detected, as described above, but the release of the locked state may also be detected when an acceleration equal to or higher than a predetermined acceleration is detected by the vehicle speed sensor 14. As the predetermined acceleration, an acceleration that can be used to determine that the hybrid vehicle 1 has released the locked state is used.

[0055] The hybrid control unit 10 functions as a front wheel spin detector 102, which detects that the front wheel 6 is spinning when, during the lock release control, it is detected that the rotational speed of the front wheel 6 detected by the vehicle wheel speed sensor 13 is equal to or higher than a predetermined rotational speed, or a change amount of the rotational speed of the front wheel 6 is equal to or greater than a predetermined change amount. All of the predetermined rotational speed and the predetermined change amount described above are the rotational speed and the change amount that can be used to determine that the front wheel 6 is spinning, and they are obtained in advance through an experiment and stored in the ROM of the hybrid control unit 10.Furthermore, the hybrid control unit 10 may detect that the front wheel 6 has slipped according to a detection method other than the detection method described above.

[0056] The hybrid control unit 10 is configured to control the electric motor generator 3 during the electric motor torque reduction control such that the electric motor torque becomes 0 when a portion of the electric motor torque that occupies the drive torque (the torque Tmax in Fig. 3) issued by the controller for termination of a blockage is equal to or greater than a predetermined value TH1.

[0057] The hybrid control unit 10 is configured to perform control for regeneratively driving the electric motor generator 3 during the electric motor torque reduction control when the proportion of the electric motor torque that occupies the drive torque (the torque Tmax in Fig. 3) issued by the controller to terminate a blockage is less than the specified value TH1.

[0058] Here, when the rotation of the electric motor torque occupying the drive torque output by the lock-up release control is high, it is possible to promptly reduce the drive torque by simply setting the electric motor torque, which has a high responsiveness compared with the engine torque, to 0.

[0059] On the other hand, when the proportion of the electric motor torque occupying the drive torque output by the lock-up release control is small, that is, when the proportion of the engine torque is high, it is not possible to reduce the drive torque simply by setting the electric motor torque to 0. In this case, as described above, it is possible to promptly reduce the drive torque by regeneratively driving the electric motor generator 3.

[0060] Taking such a point into consideration, according to this embodiment, the predetermined value TH1, which is a reference for determining whether to set the motor torque to 0 or to regenerate the motor generator 3, is set. The predetermined value TH1 is a lower limit value for the proportion of the motor torque capable of suppressing the slippage of the front wheel 6 simply by setting the motor torque to 0, even when there is a response delay in reducing the engine torque.

[0061] Next, with reference to Fig. 4 describes a process flow for determining whether the control performed by the hybrid control unit 10 is to be performed for terminating a blockage. Fig. The process shown in Figure 4 is repeatedly performed by the hybrid control unit 10 at a predetermined time interval.

[0062] As in Fig. 4, the hybrid control unit 10 determines whether the termination switch 15 is turned on, that is, whether the termination switch 15 is pressed (step S1).

[0063] The hybrid control unit 10 terminates the Fig. 4 when it is determined that the termination switch 15 is not turned on.

[0064] When it is determined that the termination switch 15 is turned on, the hybrid control unit 10 determines whether the accelerator opening degree sensor 12 detects depression of the accelerator pedal (not shown) by the driver within a predetermined period of time after the termination switch 15 is turned on (step S2).

[0065] If it is determined that the accelerator opening degree sensor 12 does not detect any depression of the accelerator pedal within a predetermined period of time after the termination switch 15 is turned on, the hybrid control unit 10 terminates the Fig. 4 process shown.

[0066] When it is determined that the accelerator opening degree sensor 12 detects the depression of the accelerator pedal within a predetermined period of time after the termination switch 15 is turned on, the hybrid control unit 10 performs the lock termination control (step S3) and terminates the Fig. 4 process shown.

[0067] Next, with reference to the Fig. 5 and Fig. 6 describes a process flow during the control for the termination of a blockage. The Fig. The process shown in Fig. 5 is repeatedly performed by the hybrid control unit 10 during the control for termination of a blockage at a predetermined time interval.

[0068] As in Fig. As shown in Figure 5, the hybrid control unit 10 determines whether the hybrid vehicle 1 has exited the locked state (step S11). If the relation vehicle speed > 0 is detected after the lock of the hybrid vehicle 1 or the start of the lock-up exit control is determined, the hybrid control unit 10 determines that the hybrid vehicle 1 has exited the locked state.

[0069] When it is determined that the hybrid vehicle 1 has not exited the locked state in step S11, the hybrid control unit 10 allows the process to proceed to step S14.

[0070] If it is determined that the hybrid vehicle 1 has exited the locked state in step S11, the hybrid control unit 10 determines whether the front wheel 6 is spinning (step S12). If it is detected that the rotational speed of the front wheel 6 detected by the vehicle wheel speed sensor 13 is equal to or higher than a predetermined rotational speed, or a change amount of the rotational speed of the front wheel 6 is equal to or greater than a predetermined change amount, the hybrid control unit 10 determines that the front wheel 6 is spinning.

[0071] If it is determined in step S12 that the front wheel 6 is not slipping, the hybrid control unit 10 allows the process to proceed to step S14. If it is determined in step S12 that the front wheel 6 is slipping, the hybrid control unit 10 allows the process to proceed to step S13.

[0072] In step S13, the hybrid control unit 10 executes the Fig. 6 and terminates the control shown in Fig. 5. The electric motor torque reduction control will be explained later with reference to Fig. 6 described.

[0073] In step S14, the hybrid control unit 10 determines whether the driver's depression of the accelerator pedal is maintained.

[0074] If it is determined in step S14 that the driver's depression of the accelerator pedal is maintained, the hybrid control unit 10 continues the lock-up termination control (step S15) and terminates the Fig. 5 process shown.

[0075] When the driver does not maintain the accelerator pedal depression, that is, when the accelerator pedal depression is released in step S14, the hybrid control unit 10 ends the lock-up termination control (step S16) and ends the Fig. 5 process shown.

[0076] Next, with reference to Fig. 6 a flow of a process shown in step S13 of Fig. 5 is described. The torque reduction control performed in Fig. The motor torque reduction control process shown in Fig. 6 is performed when, during the lock-up termination control, advancing to step S13 of Fig. 5 is carried out.

[0077] As in Fig. 6, the hybrid control unit 10 determines whether the proportion of the electric motor torque that occupies the drive torque output from the lock-up cancellation controller is equal to or greater than the predetermined value TH1 (step S21).

[0078] When it is determined in step S21 that the proportion of the motor torque that occupies the drive torque is equal to or greater than the predetermined value TH1, the hybrid control unit 10 sets the motor torque output from the motor generator 3 to 0 (step S22) and allows the process to proceed to step S24.

[0079] If it is determined in step S21 that the proportion of the motor torque occupies the drive torque is not equal to or greater than the predetermined value TH1, the hybrid control unit 10 sets the motor torque output from the motor-generator 3 to a negative value (step S23) and allows the process to proceed to step S24. In step S23, the hybrid control unit 10 regeneratively drives the motor-generator 3 to output regenerative torque.

[0080] In step S24, the hybrid control unit 10 controls the engine 2 such that the engine torque becomes 0 (step S24) and ends the Fig. 6 shown process of electric motor torque reduction control.

[0081] As described above, the hybrid vehicle according to this embodiment is configured to perform the electric motor torque reduction control when it is detected that the hybrid vehicle 1 has released the locked state and the front wheel 6 has slipped during the lock release control.

[0082] With this configuration, the hybrid vehicle according to this embodiment can suppress the slipping and spinning of the front wheel 6 or the jumping of the hybrid vehicle when it exits the locked state. Accordingly, the hybrid vehicle according to this embodiment can smoothly transition to the drive state when it exits the locked state.

[0083] Furthermore, the hybrid vehicle according to this embodiment is configured to set the electric motor torque to 0 during the electric motor torque reduction control when a proportion of the electric motor torque occupying the drive torque outputted by the lock-up cancellation controller is equal to or greater than the predetermined value TH1.

[0084] With this configuration, the hybrid vehicle according to this embodiment can promptly reduce the drive torque simply by setting the electric motor torque, which has a high responsiveness compared with the engine torque, to 0 when the proportion of the electric motor torque that occupies the drive torque is high.

[0085] Furthermore, the hybrid vehicle according to this embodiment is configured to regeneratively drive the electric motor generator 3 during the electric motor torque reduction control when the proportion of the electric motor torque occupying the drive torque output by the lock-up release control is less than the predetermined value TH1.

[0086] With this configuration, the hybrid vehicle according to this embodiment can promptly reduce the drive torque by regeneratively driving the electric motor generator 3 when the proportion of the electric motor torque that occupies the drive torque is small.

[0087] Furthermore, the hybrid vehicle according to this embodiment is configured to output the drive torque by the power of the electric motor generator 3 until a predetermined period of time elapses after the lock-up cancellation control is started, and to increase the engine torque while decreasing the motor torque after a predetermined period of time elapses.

[0088] With this configuration, the hybrid vehicle according to this embodiment can output high drive torque from the high-response electric motor generator 3 for releasing the locked state during a predetermined period from the start of the lock release control from an early stage. Furthermore, it is possible to attempt to release the locked state while keeping electric power consumption low by increasing the engine torque after a predetermined period has elapsed.

[0089] Furthermore, since the hybrid vehicle according to this embodiment is a four-wheel drive vehicle with the transmission unit 5, the torque balance of the front wheel 6 and the rear wheel 7 does not change suddenly even if the electric motor torque is set to 0 or regenerative driving is performed when the locked state is released. Therefore, the hybrid vehicle according to this embodiment can prevent a decrease in driving stability when the locked state is released.

[0090] Furthermore, a configuration according to this embodiment has been described in which the proportion of the motor torque occupies the drive torque output by the lock release controller is compared with the predetermined value TH1 to determine whether to set the motor torque to 0 or to regenerate the motor generator 3. However, this invention is not limited to this. For example, the following configuration can be adopted.

[0091] That is, the hybrid control unit 10 controls the electric motor generator 3 during the electric motor torque reduction control so that the electric motor torque becomes 0 when a portion of the engine torque occupying the drive torque (the torque Tmax in Fig. 3) issued by the control for terminating a blockage is less than a predetermined value TH2.

[0092] Furthermore, the hybrid control unit 10 is configured to perform control during the motor torque reduction control in which the motor generator 3 is regeneratively driven when a portion of the engine torque occupying the drive torque (the torque Tmax in Fig. 3) issued by the controller for termination of a blockage is equal to or greater than a predetermined value.

[0093] The predetermined value TH2 of this case is the lower limit of the proportion of the engine torque that is unable to prevent the slipping of the front wheel 6 when the electric motor generator 3 is not regeneratively driven.

[0094] Furthermore, in this embodiment, the lock release control has been described as increasing the drive torque by not setting the upper limit for the drive torque for a state where the lock release control is not performed, but this invention is not limited to this. For example, the lock release control may have a configuration in which the drive torque is corrected with respect to the amount of accelerator operation and the vehicle speed to increase it compared to the state where the lock release control is not performed. Accordingly, the drive torque increases when the lock release control is performed.

[0095] Furthermore, the hybrid vehicle according to this invention can also be applied to a hybrid vehicle 1A which is Fig. 7. In the embodiment of the Fig. 7, the same reference numerals are used in the same configurations as in the embodiment of the hybrid vehicle 1.

[0096] The Fig. The hybrid vehicle 1A shown in Fig. 7 differs from the hybrid vehicle 1 of this embodiment in that an electric motor generator 3A is provided on the power transmission path between the engine 2 and the transmission 4, and the ISG is not connected to the engine 2.

[0097] In the hybrid vehicle 1A, a battery 81A, which is configured as a lead storage battery, for example, and the battery 31, which is configured as a lithium-ion battery, for example, are connected by a DCDC converter 82 (referring to the Fig. 7 referred to as “DCDC”) are interconnected.

[0098] Although embodiments of this invention have been described, it will be apparent that those skilled in the art may make changes without departing from the scope of this invention. Any and all such modifications and equivalents are intended to be included in the appended claims. (DESCRIPTION OF REFERENCE SYMBOLS)

[0099] 1 ... hybrid vehicle, 2 ... internal combustion engine, 3 ... electric motor generator (electric motor), 4 ... transmission, 5 ... transmission unit, 6 ... front wheel, 7 ... rear wheel, 10 ... hybrid control unit (drive control unit), 11 ... battery sensor, 12 ... accelerator opening degree sensor, 13 ... vehicle wheel speed sensor, 14 ... vehicle speed sensor, 15 ... termination switch, 101 ... lock termination detector, 102 ... front wheel spin detector

Claims

[1] Hybrid vehicle (1) in which a front wheel (6) and a rear wheel (7) are driven by a power from one or both of an internal combustion engine (2) and an electric motor (3), the hybrid vehicle (1) comprising: a drive control unit (10) capable of performing a lock-up termination control in which a drive torque of the hybrid vehicle (1) is increased so that the hybrid vehicle (1) terminates a locked state when a predetermined operation is performed, wherein the drive control unit (10) performs an electric motor torque reduction control in which an electric motor torque corresponding to a torque of the electric motor (3) is reduced when it is detected that the hybrid vehicle (1) has ended the locked state and the front wheel (6) has slipped during the lock-out control, wherein the drive control unit (10) controls the electric motor (3) during the electric motor torque reduction control so that the electric motor torque becomes zero when a proportion of the electric motor torque occupies the drive torque output by the lock-up release control is equal to or greater than a predetermined value, and controls the electric motor (3) in a regenerative drive mode when the proportion of the electric motor torque occupies the drive torque output by the lock-up release control is less than the predetermined value. [2] The hybrid vehicle (1) according to claim 1, wherein the drive control unit (10) outputs the drive torque by the power of the electric motor (3) until a predetermined period of time has elapsed after starting the lock-up cancellation control, and increases an engine torque corresponding to a torque of the engine (2) while decreasing the electric motor torque after the predetermined period of time has elapsed. [3] Hybrid vehicle (1) according to claim 1 or 2, further comprising: a transmission unit (5) which distributes the drive torque output by at least one of the internal combustion engine (2) and the electric motor (3) to the front wheel (6) and the rear wheel (7).

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