JP5436330B2 - Hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle including an internal combustion engine, an electric motor, and an automatic transmission.

  For example, Patent Document 1 below discloses an automatic transmission that is a hybrid vehicle having a motor (electric motor) and an engine (internal combustion engine) as drive sources and includes a dual clutch having two input shafts as a power transmission mechanism. An onboard vehicle is disclosed. In this hybrid vehicle, a technique for controlling braking (regenerative braking) by motor regeneration has been proposed.

JP 2009-166611 A

  However, when the storage amount of the storage battery that supplies power to the electric motor is the upper limit, the storage battery cannot be charged by regeneration of the electric motor, and therefore no braking force is generated by regenerative braking. In the hybrid vehicle of Patent Document 1 described above, the amount of electricity stored in the storage battery is not taken into account during regenerative braking. Therefore, when the amount of electricity stored in the storage battery reaches the upper limit, the braking force of the vehicle may decrease.

  Accordingly, an object of the present invention is to provide a hybrid vehicle that suppresses a decrease in braking force of the vehicle even when the amount of power stored in the storage battery reaches an upper limit when braking is performed only by regenerative braking of the electric motor. And

The present invention is a hybrid vehicle having an internal combustion engine and an electric motor as drive sources, a storage battery that is a power source of the electric motor and is charged with electric power generated by the electric motor, and a driving force of the electric motor is input, A first input shaft to which the driving force of the internal combustion engine is input via the first connection / disconnection means, a second input shaft to which the driving force of the internal combustion engine is input via the second connection / disconnection means, and the first input An output shaft to which the shaft or the second input shaft is selectively connected, and the driving force input from the internal combustion engine and the electric motor to the first input shaft or the second input shaft is changed to change the speed. An automatic transmission that outputs from the output shaft; a braking device that decelerates the vehicle; and a control unit that controls braking based on a required braking force. The control unit performs braking only by regeneration of the electric motor. The storage battery When the amount is equal to or greater than a predetermined value or when an abnormality occurs in the electric motor, the internal combustion engine generates a braking force due to rotation by setting the first connecting / disconnecting means, and the requested braking force The hybrid is controlled so that a braking force obtained by reducing the braking force generated by the rotation of the internal combustion engine and the braking force generated by the braking device is generated by regeneration of the electric motor, and the braking force is generated by regeneration of the electric motor. Control is performed so that the internal combustion engine is stopped and the first connecting / disconnecting means travels in a connected state when an acceleration request is generated in the vehicle and the storage amount of the storage battery is equal to or greater than a predetermined value. (First invention).

According to the present invention, when the storage amount of the storage battery is equal to or greater than a predetermined value or when an abnormality occurs in the electric motor, the braking force due to the rotation of the internal combustion engine is set by connecting the first connecting / disconnecting means from the required braking force. Since the braking force obtained by reducing the braking force by the braking device is generated by the regeneration of the electric motor, even if the braking force generated by the regeneration of the electric motor is reduced, the decrease in the braking force of the vehicle can be suppressed.
Further, when the braking request is generated by the regeneration of the electric motor and the acceleration request is generated in the hybrid vehicle and the storage amount of the storage battery is equal to or higher than the predetermined value, the internal combustion engine is stopped and the first connection / disconnection is performed. The motor outputs the driving force to the automatic transmission and the driving force to rotate the internal combustion engine by running the means while being connected, and the storage amount of the storage battery is increased from a predetermined value (for example, an upper limit value). Can be suppressed.

  In the first aspect of the invention, the control means is configured such that a braking force obtained by subtracting a braking force generated by rotation of the internal combustion engine and a braking force generated by the braking device from a required braking force is greater than a braking force that can be generated by regeneration of the electric motor. In this case, it is preferable that the second connecting / disconnecting means is controlled to generate a frictional force so as to increase a braking force (second invention).

  According to this, when the motor must output a braking force larger than the braking force that can be generated by the regeneration of the motor, the frictional force is generated and the braking force is increased by putting the second connecting / disconnecting means in the connected state. By doing so, a decrease in the braking force of the vehicle can be suppressed.

  In the first or second aspect of the invention, the control means is a brake that can generate a braking force, which is obtained by subtracting a braking force due to rotation of the internal combustion engine and a braking force due to the braking device from a required braking force, by regeneration of the electric motor. If it is larger than the motive power and necessary for operation, the time required for control to satisfy the required braking force is limited, and the electric motor even if the electric power generation amount of the electric motor or the storage amount of the storage battery exceeds a predetermined upper limit value It is preferable to control so as to increase the braking force due to regeneration (third invention).

  According to this, when the braking force obtained by subtracting the braking force by the rotation of the internal combustion engine and the braking force by the braking device from the requested braking force is larger than the braking force that can be generated by regeneration of the electric motor, the requested braking force is not reached. Therefore, the braking force of the vehicle is insufficient. However, when it is necessary for driving, for example during sudden braking, the power generation of the motor is limited by limiting the control time to satisfy the required braking force in order to prevent overcharging of the storage battery. Even if the amount or the amount of electricity stored in the storage battery exceeds a predetermined upper limit, the braking force due to regeneration of the electric motor is increased. As a result, a decrease in braking force of the vehicle can be suppressed to compensate for a lack of braking force.

The figure which shows schematic structure of the hybrid vehicle which concerns on embodiment of this invention. Explanatory drawing which shows zoning of SOC of a storage battery. The table | surface which shows the permission and restriction | limiting of the deceleration regeneration according to the zone of SOC of a storage battery. The figure which shows the ratio of each braking force with respect to the request | requirement braking force by braking mode. The figure which shows an example of the time change of each braking force of regenerative braking, an engine brake, and a mechanical brake with respect to the request | requirement braking force Treq in embodiment of this invention. The flowchart which shows the process sequence of the brake control which ECU21 of FIG. 1 performs.

  FIG. 1 is a diagram showing a schematic configuration of a hybrid vehicle according to an embodiment of the present invention. As shown in FIG. 1, the hybrid vehicle has an internal combustion engine ENG that is an engine, an electric motor (motor) MG, a storage battery BATT that is a secondary battery that exchanges power with the motor MG, an automatic transmission 31, and a vehicle traveling speed that is reduced. A mechanical brake (braking device) BRK and an electronic control unit ECU (Electronic Control Unit) 21 for controlling each part of the engine ENG, the motor MG, the automatic transmission 31, and the mechanical brake BRK are provided.

  The ECU 21 includes a CPU 21a that executes various arithmetic processes and a storage device (memory) 21b that includes a ROM and a RAM that store various arithmetic programs executed by the CPU 21a, various tables, calculation results, and the like, and inputs various electric signals. In addition, a drive signal is output to the outside based on the calculation result.

  In the present embodiment, the CPU 21a of the ECU 21 functions as the control means 21a1 in the present invention.

  The ECU 21 is supplied with an output signal of an accelerator opening sensor 22 that detects an operation amount of an accelerator pedal (not shown).

  The mechanical brake BRK is configured by a hydraulic brake that operates by hydraulic pressure, and brakes the vehicle according to an operation amount of a brake pedal (not shown). The braking force generated by the mechanical brake BRK is controlled by the ECU 21.

  The mechanical brake BRK is not limited to a hydraulic brake, and may be any device that can control a braking force, such as a disc brake.

  The lock mechanism R1 is not limited to the synchromesh mechanism, and includes a friction engagement release mechanism such as a sleeve, a wet multi-plate brake, a hub brake, a band brake, a one-way clutch, a two-way clutch, and the like. May be.

  The automatic transmission 31 includes an engine output shaft 32 to which the driving force (output torque) of the engine ENG is transmitted and an output gear that outputs power to the left and right front wheels as drive wheels via a differential gear (not shown). A member 33 and a plurality of gear trains G2 to G5 having different gear ratios are provided.

  The automatic transmission 31 includes a first input shaft 34 that rotatably supports the drive gears G3a and G5a of the odd-numbered gear trains G3 and G5 that establish odd-numbered gear positions in the gear ratio order, and a gear ratio. A second input shaft 35 that rotatably supports the drive gears G2a and G4a of the even-numbered gear trains G2 and G4 that establish even-numbered gear positions in order, and a reverse shaft 36 that rotatably supports the reverse gear GR. Is provided. The first input shaft 34 is disposed on the same axis as the engine output shaft 32, and the second input shaft 35 and the reverse shaft 36 are disposed in parallel with the first input shaft 34.

  The automatic transmission 31 includes an idle drive gear Gia rotatably supported on the first input shaft 34, a first idle driven gear Gib fixed to the idle shaft 37 and meshed with the idle drive gear Gia, The idle gear train Gi includes a second idle driven gear Gic fixed to the input shaft 35 and a third idle driven gear Gid fixed to the reverse shaft 36 and meshed with the first idle drive gear Gib. The idle shaft 37 is arranged in parallel with the first input shaft 34.

  The automatic transmission 31 includes a first clutch C1 and a second clutch C2 that are hydraulically operated dry friction clutches or wet friction clutches. The first clutch C1 switches between a transmission state in which the driving force of the engine ENG transmitted to the engine output shaft 32 can be transmitted to the first input shaft 34 by changing the transmission degree, and an open state in which this transmission is cut off. It is configured freely. The second clutch C2 switches between a transmission state in which the driving force of the engine ENG transmitted to the engine output shaft 32 can be transmitted to the second input shaft 35 by changing the transmission degree, and an open state in which this transmission is cut off. It is configured freely. When the second clutch C2 is engaged and the transmission state is established, the engine output shaft 32 is connected to the second input shaft 35 via the first idle drive gear Gib and the second idle drive gear Gic.

  Both clutches C1 and C2 are preferably operated by an electric actuator so that the state can be quickly switched. Both clutches C1 and C2 may be operated by a hydraulic actuator.

  Further, the automatic transmission 31 is provided with a planetary gear mechanism PG which is a differential rotation mechanism and is positioned coaxially with the engine output shaft 32. The planetary gear mechanism PG is configured as a single pinion type including a sun gear Sa, a ring gear Ra, and a carrier Ca that pivotally supports and rotates a pinion Pa meshing with the sun gear Sa and the ring gear Ra.

  Three rotation elements including the sun gear Sa, the carrier Ca, and the ring gear Ra of the planetary gear mechanism PG are separated by a distance corresponding to a gear ratio in a speed diagram (a diagram showing a relative rotation speed of each rotation element as a straight line). Are the first rotating element, the second rotating element, and the third rotating element from the sun gear Sa side in the order in which the first rotating element is the sun gear Sa, the second rotating element is the carrier Ca, and the third rotating element is the ring gear Ra. Become.

  Then, with the gear ratio of the planetary gear mechanism PG (the number of teeth of the ring gear Ra / the number of teeth of the sun gear Sa) as g, the distance between the sun gear Sa as the first rotating element and the carrier Ca as the second rotating element and the second rotation The ratio between the carrier Ca as the element and the distance between the ring gear Ra as the third rotating element is g: 1.

  The sun gear Sa as the first rotating element is fixed to the first input shaft 34. The carrier Ca as the second rotating element is connected to the third speed drive gear G3a of the third speed gear train G3. The ring gear Ra, which is the third rotating element, is releasably fixed to a stationary part such as a transmission case by a lock mechanism R1.

  The lock mechanism R1 includes a synchromesh mechanism that can be switched between a fixed state in which the ring gear Ra is fixed to the non-moving portion and an open state in which the ring gear Ra is freely rotatable.

  The lock mechanism R1 is not limited to the synchromesh mechanism, and includes a friction engagement release mechanism such as a sleeve, a wet multi-plate brake, a hub brake, a band brake, a one-way clutch, a two-way clutch, and the like. May be. The planetary gear mechanism PG is a double pinion type comprising a sun gear, a ring gear, and a carrier that rotatably supports and rotates a pair of pinions Pa and Pa ′ that mesh with each other and engage with the sun gear and the other with the ring gear. You may comprise. In this case, for example, the sun gear (first rotating element) is fixed to the first input shaft 34, the ring gear (second rotating element) is connected to the third speed drive gear G3a of the third speed gear train G3, and the carrier (third rotation) The element) may be configured to be releasably fixed to the non-moving portion by the lock mechanism R1.

  A hollow motor MG is disposed outward in the radial direction of the planetary gear mechanism PG. In other words, the planetary gear mechanism PG is disposed inside the hollow motor MG. The motor MG includes a stator MGa and a rotor MGb.

  The motor MG is controlled via the power drive unit PDU based on the instruction signal from the ECU 21. The ECU 21 generates the power drive unit PDU by driving the motor MG while consuming the electric power of the storage battery BATT and suppressing the rotational force of the rotor MGb, and generates the generated power to the storage battery BATT via the power drive unit PDU. Switch to the regenerative state to charge as appropriate.

  A first driven gear Go1 that meshes with the second speed drive gear G2a and the third speed drive gear G3a is fixed to the output shaft 33a that supports the output member 33. A second driven gear Go2 that meshes with the fourth speed drive gear G4a and the fifth speed drive gear G5a is fixed to the output shaft 33a.

  Thus, by configuring the driven gears of the second gear train G2 and the third gear train G3 and the driven gears of the fourth gear train G4 and the fifth gear train G5 with one gear Go1, Go2, respectively, The shaft length of the transmission can be shortened, and the FF (front wheel drive) system can be mounted on a vehicle.

  A reverse driven gear GRa that meshes with the reverse gear GR is fixed to the first input shaft 34.

  The first input shaft 34 is composed of a synchromesh mechanism, and the third speed drive gear G5a is connected to the first input shaft 34. The third speed drive gear G5a is connected to the first input shaft 34. 1st mesh which is the 1st selection means which can be changed to any state of the neutral state which cuts connection with the 5th speed side connection state, 3rd speed drive gear G3a and 5th speed drive gear G5a, and the 1st input shaft 34 A mechanism SM1 is provided.

  The second input shaft 35 is composed of a synchromesh mechanism, and is connected to the second speed drive gear G4a and the second input shaft 35. The second speed drive gear G2a and the second input shaft 35 are connected to each other. The second meshing which is the second selection means which can be switched to any state of the neutral state in which the connection between the second speed driving gear G2a and the fourth speed driving gear G4a and the second input shaft 35 is disconnected. A mechanism SM2 is provided.

  The reverse shaft 36 includes a synchromesh mechanism, and a third meshing mechanism SM3 that can be switched between a connected state in which the reverse gear GR and the reverse shaft 36 are connected and a neutral state in which the connection is broken is selectable. Is provided.

  Next, the operation of the automatic transmission 31 configured as described above will be described.

  In the automatic transmission 31, by engaging the first clutch C1, it is possible to perform IMA start for starting the engine ENG using the driving force of the motor MG.

  When the first gear is established using the driving force of the engine ENG, the ring gear Ra of the planetary gear mechanism PG is fixed by the lock mechanism R1, and the first clutch C1 is engaged to set the transmission state.

  The driving force of the engine ENG is input to the sun gear Sa of the planetary gear mechanism PG via the engine output shaft 32, the first clutch C1, and the first input shaft 34, and the rotational speed of the engine ENG input to the engine output shaft 32 Is decelerated to 1 / (g + 1) and transmitted to the third-speed drive gear G3a via the carrier Ca.

  The driving force transmitted to the third-speed drive gear G3a is the gear ratio of the third-speed gear train G3 composed of the third-speed drive gear G3a and the first driven gear Go1 (number of teeth of the third-speed drive gear G3a / first driven gear). The number of teeth of Go1) is i, and the gear is shifted to 1 / i (g + 1) and output from the output member 33 via the first driven gear Go1 and the output shaft 33a, and the first gear is established.

  Thus, in the automatic transmission 31, the first gear can be established by the planetary gear mechanism PG and the third gear train, so that a meshing mechanism dedicated to the first gear is not required, thereby shortening the axial length of the automatic transmission. Can be achieved.

  In the first gear, the ECU 21 performs a decelerating regenerative operation in which power is generated by applying a brake with the motor MG in accordance with the remaining capacity (charge rate) SOC of the storage battery BATT in a deceleration state. Further, according to the remaining capacity SOC of the storage battery BATT, the motor MG is driven to assist HEV (Hybrid Electric Vehicle) driving of the engine ENG, or EV (Electric Vehicle) driving only with the driving power of the motor MG. It is possible to run.

  Further, when the vehicle is traveling in EV and the vehicle is allowed to decelerate and the vehicle speed is equal to or higher than a certain speed, the driving force of the motor MG is used by gradually engaging the first clutch C1. Instead, the engine ENG can be started using the kinetic energy of the vehicle.

  Further, when the ECU 21 predicts from the vehicle information such as the vehicle speed and the opening degree of the accelerator pedal that the upshift to the second gear is performed during traveling at the first gear, the second meshing mechanism SM2 is moved to the second gear. It is set as the 2nd speed side connection state which connects G2a and the 2nd input shaft 35, or the pre shift state which approaches this state.

  In the case where the second speed is established using the driving force of the engine ENG, the second meshing mechanism SM2 is brought into a second speed side connection state in which the second speed drive gear G2a and the second input shaft 35 are connected, and the second clutch C2 is fastened to the transmission state. Accordingly, the driving force of the engine ENG is output from the output member 33 via the second clutch C2, the idle gear train Gi, the second input shaft 35, the second speed gear train G2, and the output shaft 33a.

  When the ECU 21 predicts an upshift at the second speed, the first meshing mechanism SM1 is connected to the third-speed side connected state in which the third-speed drive gear G3a and the first input shaft 34 are connected or to this state. The pre-shift state is approached.

  Conversely, when the ECU 21 predicts a downshift, the first meshing mechanism SM1 is set to a neutral state in which the connection between the third drive gear G3a and the fifth drive gear G5a and the first input shaft 34 is disconnected.

  As a result, the upshift or the downshift can be performed simply by setting the first clutch C1 in the transmission state and the second clutch C2 in the disengaged state, and smoothly switching the shift speed without interrupting the driving force. Can do.

  Even at the second speed, when the vehicle is in a decelerating state, the ECU 21 performs a deceleration regenerative operation in accordance with the remaining capacity SOC of the storage battery BATT. When performing the deceleration regenerative operation in the second speed stage, it differs depending on whether the first meshing mechanism SM1 is in the third speed side connected state or in the neutral state.

  When the first meshing mechanism SM1 is in the third speed side connected state, the third drive gear G3a rotated by the first driven gear Go1 rotated by the second drive gear G2a is connected to the motor MG via the first input shaft 34. In order to rotate the rotor MGb, the rotation of the rotor MGb is suppressed and a brake is applied to generate electricity and perform regeneration.

  When the first meshing mechanism SM1 is in the neutral state, the rotation speed of the ring gear Ra is set to “0” by setting the lock mechanism R1 in a fixed state, and the gear rotates with the third speed drive gear G3a meshing with the first driven gear Go1. The rotation of the carrier Ca to be performed is generated by the motor MG connected to the sun gear Sa, so that the brake is applied and regeneration is performed.

  Further, when HEV traveling is performed at the second speed, for example, the first meshing mechanism SM1 is set to the third speed side connected state in which the third speed drive gear G3a and the first input shaft 34 are connected, and the lock mechanism R1 is opened. As a result, the planetary gear mechanism PG can be made in a state in which the rotating elements are not relatively rotatable, and the driving force of the motor MG is transmitted to the output member 33 via the third-speed gear train G3. Alternatively, the first meshing mechanism SM1 is set to the neutral state, the lock mechanism R1 is set to the fixed state, the rotation speed of the ring gear Ra is set to “0”, and the driving force of the motor MG is transmitted to the first driven gear Go1 through the first speed path. Therefore, HEV traveling at the second gear can be performed.

  When the third speed is established using the driving force of the engine ENG, the first meshing mechanism SM1 is set to the third speed side connection state in which the third speed drive gear G3a and the first input shaft 34 are connected, and the first clutch C1 is fastened to a transmission state. Thus, the driving force of the engine ENG is transmitted to the output member 33 via the engine output shaft 32, the first clutch C1, the first input shaft 34, the first meshing mechanism SM1, and the third speed gear train G3. It is output at the rotation number i.

  At the third speed, the first meshing mechanism SM1 is in the third speed side connected state in which the third speed drive gear G3a and the first input shaft 34 are connected, so the sun gear Sa of the planetary gear mechanism PG, the carrier Ca, Are the same rotation.

  Accordingly, each rotating element of the planetary gear mechanism PG becomes a state in which relative rotation is impossible, and if the sun gear Sa is braked by the motor MG, deceleration regeneration is performed, and if the driving force is transmitted to the sun gear Sa by the motor MG, HEV traveling is performed. be able to. Further, EV traveling is also possible in which the first clutch C1 is opened and the vehicle travels only with the driving force of the motor MG.

  In the third speed, the ECU 21 changes the second meshing mechanism SM2 to the second speed drive gear G2a and the second input shaft 35 when a downshift is predicted based on vehicle information such as the vehicle speed and the accelerator pedal opening. Is connected to the second speed side, or a pre-shift state approaching this state, and when an upshift is predicted, the second meshing mechanism SM2 is connected to the fourth speed drive gear G4a and the second input shaft 35. A fast-side connected state or a pre-shift state approaching this state.

  As a result, it is possible to change the gear position simply by engaging the second clutch C2 and setting the transmission state, and releasing the first clutch C1 and setting the transmission state, thereby smoothly shifting without interrupting the driving force. It can be carried out.

  In the case where the fourth speed is established using the driving force of the engine ENG, the second meshing mechanism SM2 is set to the fourth speed side coupling state in which the fourth speed driving gear G4a and the second input shaft 35 are coupled, and the second clutch C2 is fastened to a transmission state.

  If the ECU 21 predicts a downshift from the vehicle information while traveling at the fourth speed, the first meshing mechanism SM1 is connected to the third speed drive gear G3a and the first input shaft 34 in the third speed side connected state. Or a pre-shift state approaching this state.

  Conversely, when the ECU 21 predicts an upshift from the vehicle information, the first meshing mechanism SM1 is connected to the fifth speed drive gear G5a and the first input shaft 34, or this state The pre-shift state is approaching. As a result, it is possible to perform downshift or upshift by simply engaging the first clutch C1 and setting it to the transmission state, and releasing the second clutch C2 so that the shift is smooth without interruption of the driving force. Can be done.

  When performing deceleration regeneration or HEV traveling during traveling at the fourth speed, when the power transmission device ECU21 predicts a downshift, the first meshing mechanism SM1 is connected to the third speed driving gear G3a and the first input shaft 34. Is connected to the third speed side, and if the brake is applied by the motor MG, deceleration regeneration can be performed, and HEV traveling can be performed if the driving force is transmitted.

  When the ECU 21 predicts an upshift, the first meshing mechanism SM1 is brought into a 5-speed side connected state in which the 5-speed drive gear G5a and the first input shaft 34 are connected, and if the brake is applied by the motor MG, deceleration regeneration, motor If driving force is transmitted from MG, HEV traveling can be performed.

  When the fifth speed is established using the driving force of the engine ENG, the first meshing mechanism SM1 is set in the fifth speed connected state in which the fifth speed driving gear G5a and the first input shaft 34 are connected. At the fifth speed, the engine ENG and the motor MG are directly connected when the first clutch C1 is in the transmission state. Therefore, if the driving force is output from the motor MG, HEV traveling can be performed. If the motor MG brakes and generates power, deceleration regeneration can be performed.

  In addition, what is necessary is just to make the 1st clutch C1 into an open state, when performing EV driving | running | working at the 5th gear stage. Further, the engine ENG can be started by gradually engaging the first clutch C1 during EV traveling at the fifth speed.

  The ECU 21 connects the second meshing mechanism SM2 to the fourth speed drive gear G4a and the second input shaft 35 when a downshift from the vehicle information to the fourth speed is predicted during traveling at the fifth speed. A 4-speed side connected state or a pre-shift state approaching this state is set. As a result, the downshift to the fourth speed can be smoothly performed without interruption of the driving force.

  When the reverse speed is established using the driving force of the engine ENG, the second clutch C2 is set with the lock mechanism R1 in the fixed state and the third meshing mechanism SM3 in the connected state in which the reverse gear GR and the reverse shaft 36 are connected. To be in a transmission state. As a result, the driving force of the engine output shaft 32 moves backward via the second clutch C2, the idle gear train Gi, the reverse gear GR, the reverse driven gear GRa, the sun gear Sa, the carrier Ca, the third gear train G3, and the output shaft 33a. As the rotation of the direction, it is output from the output member 33, and the reverse gear is established.

  FIG. 2 shows an example in which the maximum power storage amount is divided into a plurality of regions (zones) based on the SOC of the storage battery BATT.

  Specifically, each area is a normal use area and a reference zone A zone, B zone B zone and B zone which is a discharge partial restriction area where the SOC of storage battery BATT is smaller than A zone and discharge is partially restricted Further, the storage battery BATT is divided into a C zone which is a discharge limiting region where the SOC is limited and discharge is limited, and a D zone which is a charging limiting region where the SOC of the storage battery BATT is larger than the A zone and charging is limited.

  Since the charge / discharge characteristics change depending on the temperature, the maximum charged amount may be divided in consideration of the temperature in addition to the SOC.

  The A zone is further divided into an intermediate zone A zone M where the SOC of the storage battery BATT is optimum, an A zone L where the SOC of the storage battery BATT is smaller than the A zone M, and an A zone H where the SOC of the storage battery BATT is larger than the A zone M. Has been.

  As shown in FIG. 3, the ECU 21 permits or restricts the regenerative operation during deceleration based on these areas. The regenerative operation is permitted from the C zone to the A zone H, and is executed with restrictions in the D zone. Since the storage battery BATT is charged by the regenerative operation, charging is performed in order to suppress a decrease in the SOC except for the D zone.

  In the D zone, in order not to charge the storage battery BATT, the regenerative operation is prohibited in principle. However, as will be described later, the braking force Tmgmax in which the braking force Tmg for regenerative braking is set as the upper limit of regenerative braking is used. In some cases, the regenerative operation may be performed exceptionally.

  The vehicle is controlled by the control means 21a1 of the ECU 21 so that the rotation resistance (hereinafter, “ The braking force is generated by controlling three types of braking, namely, braking by "engine braking") and regenerative braking by the power generation of the motor MG described above.

  When the SOC of the storage battery BATT decreases, the vehicle cannot be driven by the driving force of the motor MG. Therefore, as much as possible, braking is performed only by regenerative braking by the motor MG when the vehicle is decelerated. By doing so, the energy used for deceleration can be efficiently collected in the storage battery BATT.

  However, when the SOC of the storage battery BATT reaches the upper limit as described above, the regenerative braking force is not generated.

  Therefore, before the SOC of the storage battery BATT reaches the upper limit, the control means 21a1 performs braking by the engine brake and the mechanical brake BRK to suppress a decrease in the braking force of the vehicle. Performing braking with only the regenerative braking force of the motor MG is referred to as E mode, and performing braking with the braking force of the engine brake and mechanical brake BRK in addition to regeneration of the motor MG is referred to as M mode. In the M mode, braking may be performed only with the braking force of the engine brake and mechanical brake BRK. Details will be described below.

  FIG. 4 shows the ratio of each braking force to the M mode, the E mode, and the required braking force Treq. In the M mode, the ECU 21 connects the first clutch C1, and controls the engine brake braking force Teng, the mechanical brake braking force Tme, and the regenerative braking force Tmg to be the required braking force Treq. In the E mode, the ECU 21 opens the first clutch C1, and controls the regenerative braking force Tmg to be the required braking force Treq.

  When braking in the E mode is performed, if the SOC of the storage battery BATT exceeds a predetermined value α, the mode is switched to the M mode.

  The predetermined value α is set to a value equal to or lower than the upper limit of the SOC of the storage battery BATT. In the present embodiment, the boundary value between the A zone H and the D zone is set as the predetermined value α. This is because there is a transition time from when it is confirmed that the value is equal to or greater than the predetermined value α to when the regeneration is not actually performed. The predetermined value α is set in consideration of this transition time. The predetermined value α may be a fixed value or may be changed according to the vehicle speed. Further, when the SOC of the storage battery BATT becomes equal to or less than the predetermined value α, the mode is switched to the E mode.

  In the M mode, first, the braking force Teng of the engine brake is gradually increased by gradually engaging the first clutch C1. At this time, in order to generate the engine brake, the engine ENG is started when the engine ENG is not started. Thereafter, the braking by the mechanical brake BRK is gradually operated, and the braking force Tmg for regenerative braking is set to zero.

  By gradually operating the engine brake, it is possible to suppress the occurrence of a shock due to a sudden change in braking and smoothly shift to the braking of the mechanical brake BRK. When an acceleration request is generated in the vehicle, the engine ENG is rotated by operating the engine brake, so that the motor MG and the engine ENG can be driven smoothly.

  FIG. 5 shows an example of a time change of each braking force when the SOC of the storage battery BATT exceeds a predetermined value α in the present embodiment.

  The horizontal axis represents the elapsed time since the start of braking, and the vertical axis represents the braking force of the vehicle.

  As shown in the figure, the control means 21a1 controls each braking force such that the sum of the braking force Tmg of regenerative braking, the braking force Teng of the engine brake, and the braking force Tme of the mechanical brake BRK becomes the required braking force Treq.

  The control means 21a1 gradually operates the engine brake by gradually starting engagement of the first clutch C1 when the SOC of the storage battery BATT exceeds the predetermined value α at time T1. At this time, control is performed so that the braking force Tmg for regenerative braking is gradually weakened. The braking force Tmg for regenerative braking is adjusted by controlling a current flowing in a transistor circuit that consumes electric power as heat, which is configured in an inverter (not shown) connected to the motor MG. The braking force Tmg for regenerative braking is decreased by increasing the value of the flowing current, and the braking force Tmg for regenerative braking is increased by decreasing it.

  At time T2, the mechanical brake operation is gradually started, and the regenerative braking force Tmg is set to 0 at time T3.

  Each change in the braking force with respect to the above time change is stored in the memory 21b as a table according to the required braking force Treq and the traveling speed of the vehicle.

  In the M mode, the braking force Teng of the engine brake and the braking force Tme of the mechanical brake BRK are determined using the above table, and the total braking force is subtracted from the required braking force Treq to determine the braking force Tmg for regenerative braking. To do.

  Further, braking in the M mode is performed not only when the SOC of the storage battery BATT exceeds the predetermined value α, but also when the brake pedal is depressed more than a certain amount, that is, when the required braking force exceeds the predetermined value β. . This is because the braking force that can be generated by regenerative braking is smaller than the required braking force Treq. Therefore, it is necessary to increase the braking force up to the required braking force Treq by operating the engine brake or the mechanical brake BRK.

  The predetermined value β may be set to the upper limit braking force of the regenerative braking, or set so that the regenerative braking does not reach the upper limit from when the braking in the M mode is started until the actual braking force is output. May be. Further, the predetermined value β may be changed according to the traveling speed of the vehicle and the required braking force Treq.

  Further, braking in the M mode is also performed when an abnormality occurs in the motor MG. The abnormality of the motor MG means that an abnormality has occurred in the contactor (electromagnetic contactor) that opens and closes the current of the motor MG and cannot be opened. When this abnormality occurs, power is always generated when the vehicle is decelerated, and charging is performed regardless of the SOC of the storage battery BATT. Therefore, even when the SOC of the storage battery BATT is high, charging is performed, and the possibility that the storage battery BATT is damaged due to overcharging increases.

  Therefore, when an abnormality occurs in the motor MG, the occurrence of overcharging is suppressed by performing braking in the M mode.

  Whether or not an abnormality has occurred is determined by determining whether or not the current value of the motor MG detected by the current sensor connected to the motor MG is outside a predetermined range. When it is outside the range, it is judged as an abnormal state, and when it is within the range, it is judged as a normal state.

  When braking in the M mode, the braking force Tmg determined as described above may exceed the braking force Tmgmax actually set as the upper limit of the regenerative braking. In this case, it is necessary to increase the braking force.

  There are two methods for increasing the braking force.

  One is a method of increasing the braking force by the frictional force generated by gradually engaging the second clutch C2. As described above, when the first clutch C1 is engaged and driven, rotation is transmitted from the first input shaft 34 to the output shaft 33a. At this time, when the preshift is performed, the second speed side or the fourth speed stage is connected. Accordingly, the rotation of the output shaft 33a is transmitted to Gia via the second input shaft 35, Gic, and Gib. In this state, friction is generated when the second clutch C2 is gradually engaged. This friction is used for braking (corresponding to the braking force control of the second invention).

  The other is a method of increasing the braking force by increasing the power generation amount of the motor MG. When the amount of power generated by the motor MG is increased, the generation of electrical energy increases, so that the braking force increases. As described above, the amount of power generation is increased by reducing the current flowing in the transistor circuit that is configured in the inverter connected to the motor MG and that consumes power as heat (for controlling the braking force of the third invention). Equivalent).

  The upper limit of the amount of power generation and the upper limit of the SOC of the storage battery BATT to protect the damage of the storage battery BATT due to overcharging are set with a margin, so even if the preset upper limit is slightly exceeded, the storage battery BATT is immediately damaged. It is set not to. For example, the upper limit of the SOC of the storage battery BATT is set between the boundary value between the A zone H and the D zone and 100%.

  However, if regeneration is continued in a state where the upper limit is exceeded for a long period of time, there is a high possibility that the storage battery BATT will be damaged. Therefore, it is used when braking is completed in a short time (for example, 10 seconds). Therefore, for example, it is performed when the brake pedal is depressed to the maximum as in sudden braking. In this way, when it is necessary for driving, a decrease in braking force is suppressed to compensate for a lack of braking force. Alternatively, it may be performed when the traveling speed of the vehicle is low. Further, when a predetermined time is exceeded, the second clutch C2 may be gradually engaged to shift to a method of increasing the braking force.

  As described above, the ECU 21 performs regenerative braking when the braking force Tmg of regenerative braking exceeds the braking force Tmgmax set as the upper limit of regenerative braking. Therefore, the ECU 21 decelerates even when the SOC of the storage battery BATT is in the D zone. Regenerative deceleration is performed without prohibiting regeneration.

  When braking in the E mode, the braking force by the engine brake is set to 0 by shifting the first clutch C1 that has been in the connected state in the M mode to the released state.

  Next, a brake control process executed by the CPU 21a of the ECU 21 of the present embodiment will be described.

  In the present embodiment, the CPU 21a operates as the control unit 21a1 in the present invention.

  FIG. 6 is a flowchart showing the processing procedure of the control means of the present invention executed by the CPU 21a. The control processing program shown in this flowchart is called and executed every predetermined time (for example, 10 msec).

  The first step ST1 detects the accelerator opening, the traveling speed of the vehicle, the shift position, and the engine speed.

  Next, it progresses to step ST2 and it is determined whether the vehicle should decelerate. It is determined that the vehicle should be decelerated when the accelerator opening, the vehicle traveling speed, or the engine speed detected in step ST1 is decreasing. It is also determined that the vehicle should be decelerated when the brake pedal is operated. If it should not be decelerated, this control is terminated, and if it should be decelerated, the process proceeds to step ST3.

  In step ST3, the required braking force Treq is detected from the operation amount of the brake pedal of the vehicle.

  Next, the process proceeds to step ST4, where it is determined whether the required braking force Treq is equal to or greater than a predetermined value β. When the determination result is YES, the process proceeds to step ST5.

  In step ST5, it is determined whether or not an abnormality has occurred in the motor MG. If no abnormality has occurred, the process proceeds to step ST6. The determination is made based on the value detected by the current sensor as described above.

  In step ST6, it is determined whether or not the SOC of the storage battery BATT is equal to or greater than a predetermined value α. When the determination result is YES, the process proceeds to step ST7.

  In step ST7, it is determined whether or not there is a switch from the E mode to the M mode, or a switch from the M mode to the E mode. The determination result is YES when it is predicted that mode switching will be required in order to decelerate, and the determination result is NO when the mode is maintained after mode switching.

  When the determination result in step ST5 or ST7 is YES, the process proceeds to step ST8, and the clutch stroke Cst of the first clutch C1 is detected. In step ST9, the actual engine torque Tengb corresponding to the accelerator opening is detected.

  Next, the process proceeds to step ST10, and the current engagement state of the first clutch C1 (half clutch engagement state) is determined according to the clutch transmission torque conversion map determined according to the clutch stroke Cst, the engine torque Tengb, and the clutch stroke Cst. In response, the actually generated engine brake braking force Teng is detected. At this time, the gear ratio of the current gear stage is also taken into consideration. In the clutch transmission torque conversion map, torque that can be transmitted by the clutch with respect to the value of the clutch stroke Cst is tabulated and stored in the memory 21b. The braking force Teng of the engine brake is determined based on the transmittable torque obtained from this table and the gear ratio of the gear position.

  Next, proceeding to step ST11, as described above, the braking force Tme of the mechanical brake is detected by searching the table stored in the memory 21b.

  Next, the process proceeds to step ST12, and the regenerative braking force Tmg is determined by subtracting the braking force Teng of the engine brake and the braking force Tme of the mechanical brake determined in steps ST10 and ST11 from the required braking force Treq.

  The braking force Teng of the engine brake and the braking force Tme of the mechanical brake BRK determined in steps ST10 and ST11 vary depending on the elapsed time from the start of braking as shown in FIG. In order to gradually change the braking force Teng of the engine brake, the braking force Tme of the mechanical brake BRK, and the regenerative braking force Tmg of the motor MG, as shown in FIG. The ECU 21 is controlled so that the clutch stroke Cst (clutch engagement state) also changes.

  If the decision result in the step ST7 is NO, the process advances to a step ST13 to decide whether or not the current braking mode is the E mode.

  When the determination result of step ST4 is NO, the determination result of step ST6 is NO, or the determination result of step ST13 is YES, the process proceeds to step ST14, and the regenerative braking force Tmg of the motor MG is determined to be the same value as the required braking force Treq. To do.

  When the determination result in step ST13 is NO, the process proceeds to step ST15, and the braking force Tme of the mechanical brake and the braking force Teng of the engine brake are detected. The detection method is the same as in steps ST8 to ST11.

  When the process of step ST12 or ST14 ends, the process proceeds to step ST16, and it is determined whether or not the regenerative braking force Tmg is greater than the upper limit Tmgmax of the regenerative braking force. When the determination result is YES, the process proceeds to step ST17 to increase the braking force. As described above, the braking force is increased by gradually engaging the second clutch C2.

  When it is determined that the braking is sudden (when the required braking force Treq is close to the upper limit), the power generation amount of the motor MG is increased to increase the braking force. When it is determined that the braking is not sudden, the second clutch The braking force may be increased by gradually fastening C2.

  The processes of steps ST16 and ST17 correspond to the braking force control of the second and third inventions.

  When the determination result in step ST16 is NO, the process proceeds to step ST18 when the process in step ST17 ends or when the process in step ST15 ends. In this step, the vehicle is braked by the regenerative braking force of the engine brake, the mechanical brake BRK, and the motor MG detected or determined in accordance with the braking mode by the processing in the above step.

  For example, in the E mode, braking is performed with the regenerative braking force Tmg of the motor MG determined in step ST14. In the M mode, braking is performed by the braking force Tme of the mechanical brake BRK and the braking force Teng of the engine brake detected in step ST15. When the braking mode is switched, braking is performed using the regenerative braking force Tmg of the motor MG, the braking force Teng of the engine brake, and the braking force Tme of the mechanical brake BRK determined in steps ST10, ST11, and ST12. When the braking force is increased in step ST17, braking is performed with the increased braking force.

  Next, the process proceeds to step ST19, where it is determined whether there is an acceleration request and the SOC of the storage battery BATT is equal to or greater than a predetermined value α. Whether or not there is an acceleration request is determined when there is an acceleration request when the operation amount of the accelerator pedal obtained by the output signal of the accelerator opening sensor 22 increases by a predetermined value or more, and there is no acceleration request otherwise. judge. The predetermined value may be 0 or a value that is not recognized as an acceleration request.

  When there is an acceleration request, the process proceeds to step ST20 and the engine ENG is stopped. At this time, the first clutch C1 is engaged. As a result, the motor MG outputs a driving force to the automatic transmission 31 and rotates the crankshaft of the engine ENG. That is, since the driving force is required by the resistance for rotating the crankshaft of the engine ENG, the power of the storage battery BATT is used rather than when the first clutch C1 is in the released state. Thereby, the SOC of the storage battery BATT can be reduced, and a state close to the upper limit can be avoided. The predetermined value α in step ST19 may be set to a value different from the predetermined value α in step ST6.

Steps ST19 and ST20 correspond to a part of the control of the first invention.

  When the determination result of step ST19 is NO, or when the process of step ST20 is completed, the brake control process is terminated.

  As described above, when the motor MG is abnormal during deceleration of the vehicle, when the SOC of the storage battery BATT is greater than or equal to the predetermined value α, and when the required braking force Treq is greater than or equal to the predetermined value β, braking is performed in the M mode. Switch to and brake.

  In braking in M mode, the braking force Teng of the engine brake is detected (step ST10), the braking force Tme of the mechanical brake is detected (step ST11), and the total braking force of Teng and Tme is subtracted from the required braking force Treq. The regenerative braking force Tmg is determined (step ST12), and braking is executed (step ST18).

  When the regenerative braking force Tmg is equal to or greater than the upper limit Tmgmax of the regenerative braking force, the braking force is increased by engaging the second clutch C2 or increasing the power generation amount of the motor MG (step ST17), and cooperative braking. Is executed (step ST18).

  When there is an acceleration request during coordinated braking and the SOC of the storage battery BATT is equal to or greater than the predetermined value α (step ST19), the engine ENG is stopped (step ST20), and the motor ENG is rotated to rotate the engine ENG. Avoid situations where is close to the upper limit.

  Therefore, when braking is performed only by regenerative braking of the electric motor, even when the storage amount of the storage battery reaches the upper limit, it is possible to suppress a decrease in the braking force of the vehicle.

  21 ... ECU, 21a ... CPU, 21a1 ... control means, 21b ... memory, 31 ... automatic transmission, 34 ... first input shaft, 35 ... second input shaft, BATT ... storage battery, BRK ... mechanical brake (braking device), C1: first clutch (first connecting / disconnecting means), C2: second clutch (second connecting / disconnecting means), ENG: engine (internal combustion engine), MG: motor (electric motor).

Claims (3)

A hybrid vehicle having an internal combustion engine and an electric motor as drive sources,
A storage battery that is a power source of the electric motor and is charged with electric power generated by the electric motor;
A driving force of the electric motor is input, a driving force of the internal combustion engine is input via a first connection / disconnection means, a first input shaft, and a driving force of the internal combustion engine is input via a second connection / disconnection means. A second input shaft, and an output shaft to which the first input shaft or the second input shaft is selectively connected; and from the internal combustion engine and the electric motor to the first input shaft or the second input shaft, respectively. An automatic transmission that shifts an input driving force and outputs it from the output shaft;
A braking device for decelerating the vehicle;
Control means for controlling braking based on the required braking force,
In a case where braking is performed only by regeneration of the electric motor, the control means connects the first connecting / disconnecting means when the storage amount of the storage battery exceeds a predetermined value or when an abnormality occurs in the electric motor. Thus, the internal combustion engine generates a braking force by rotation, and a braking force obtained by subtracting the braking force by the rotation of the internal combustion engine and the braking force by the braking device from the required braking force is generated by regeneration of the electric motor. When the acceleration request is generated in the hybrid vehicle and the storage amount of the storage battery is not less than a predetermined value when the braking force is generated by the regeneration of the electric motor, the internal combustion engine is A hybrid vehicle characterized in that the vehicle is controlled so as to stop and travel with the first connecting / disconnecting means connected . The hybrid vehicle according to claim 1,
When the braking force obtained by subtracting the braking force by the rotation of the internal combustion engine and the braking force by the braking device from the required braking force is greater than the braking force that can be generated by regeneration of the electric motor, the control means A hybrid vehicle, characterized in that a braking force is increased by generating a frictional force by bringing the connecting / disconnecting means into a connected state. In the hybrid vehicle according to claim 1 or 2,
When the braking force obtained by subtracting the braking force generated by the rotation of the internal combustion engine and the braking force generated by the braking device from the required braking force is greater than the braking force that can be generated by regeneration of the electric motor and is necessary for operation. Limits the control time to satisfy the required braking force, and increases the braking force due to regeneration of the motor even if the power generation amount of the motor or the storage amount of the storage battery exceeds a predetermined upper limit value. A hybrid vehicle characterized by controlling.

Images