JP5338300B2 - Engine start control device and engine start control method - Google Patents

Description

  The present invention relates to a technology for engine start control in a hybrid vehicle that can drive a vehicle with the power of a motor and can start an engine with the power of the motor.

As a technology for engine start control of a hybrid vehicle, there is a technology described in Patent Document 1. In this technique, when engine power is required during running with the power of the motor, the target clutch fastening force is gradually increased from 0 for the clutch interposed between the engine and the motor. The engine is cranked by the gradual increase of the clutch engagement force by this, and when the engine speed reaches the startable speed, the engine is started by an engine start command. During this start-up, torque fluctuations occur in the engine, so that the target clutch engagement force is maintained and the increase of the clutch engagement force is prohibited. As a result, the clutch engagement capacity is kept small during engine startup, and torque fluctuations during startup are absorbed by the slip of the clutch.
JP 2005-162142 A

However, the clutch for controlling the transmission torque has a large variation in individual parts, and there is a possibility that the variation becomes large due to wear due to deterioration with time or a change in the oil amount.
In view of the above-described points, it is an object of the present invention to provide a technology for engine start control of a hybrid vehicle that can absorb torque fluctuation due to clutch variation.

  In order to solve the above-described problems, the present invention controls the rotational speed of the motor and controls the second clutch to be engaged and slipped with a target clutch transmission torque command when the engine is started while running only with the power of the motor. In addition, by engaging and controlling the first clutch with a predetermined clutch transmission torque, the engine is started by cranking while ensuring the vehicle is driven by the power of the motor. At this time, the slip state of the second clutch during the cranking is estimated, and the clutch transmission torque of the second clutch during engine start control is appropriately adjusted so that the slip state of the second clutch approaches appropriately. Is corrected with respect to the target clutch transmission torque command.

  The clutch transmission torque of the second clutch during the engine start control is corrected so that the slip state of the second clutch approaches appropriately. When the slip state of the second clutch approaches appropriately, it is possible to provide a technology for engine start control of a hybrid vehicle that can absorb torque fluctuation due to clutch variation.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a rear-wheel drive hybrid vehicle including the braking / driving device of the embodiment.
(Constitution)
First, the configuration of the drive system will be described.
A motor MG and an automatic transmission AT (= transmission T / M) are interposed in the middle of the torque transmission path from the engine E to the left and right rear wheels (drive wheels). The second clutch CL2 constitutes a part of the automatic transmission AT (= transmission T / M). Further, the first clutch CL1 is interposed between the engine E and the motor MG. The automatic transmission AT is connected to drive wheels via a propeller shaft PS, a differential DF, and drive shafts DSL and DSR. Reference symbols FL and FR indicate left and right front wheels as driven wheels.

The engine E is a gasoline engine or a diesel engine. The engine can control the valve opening of the throttle valve and the like based on a control command from an engine controller 1 described later. A flywheel FW is provided on the output shaft of the engine E.
The motor MG is a synchronous motor in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator, for example. The motor MG can be controlled by applying a three-phase AC generated by the inverter 3 based on a control command from the motor controller 2 described later. The motor MG can also operate as an electric motor that rotates by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “power running”). Further, when the rotor is rotated by an external force, the motor MG can function as a generator that generates an electromotive force at both ends of the stator coil to charge the battery 4 (hereinafter, this operation state is referred to as “ Called "regeneration"). Note that the rotor of the motor MG is connected to the input shaft of the automatic transmission AT via a damper (not shown).

  The first clutch CL1 is a hydraulic single-plate clutch interposed between the engine E and the motor MG. The first clutch CL1 is engaged or disengaged according to a control oil pressure generated by the first clutch hydraulic unit 6 so as to have a predetermined clutch transmission torque based on a control command from a first clutch controller 5 described later. It becomes. The fastening / opening includes sliding fastening and sliding opening.

The second clutch CL2 is a hydraulic multi-plate clutch. The second clutch CL2 is brought into an engaged state or a released state by a control hydraulic pressure generated by the second clutch hydraulic unit 8 so as to obtain a predetermined clutch transmission torque based on a control command from the AT controller 7 described later. The fastening / opening includes sliding fastening and sliding opening.
The automatic transmission AT is a transmission that automatically switches, for example, a stepped gear ratio such as 5th forward reverse 1st speed or 6th forward reverse 1st speed according to vehicle speed, accelerator opening, or the like. Here, the second clutch CL2 is not newly added as a dedicated clutch, and some of the frictional engagement elements that are engaged at each gear stage of the automatic transmission AT are used. And configure.

  Each wheel FR, FL, RR, RL is provided with a brake unit. Each brake unit includes, for example, a disc brake and a drum brake. Each brake unit may be a hydraulic brake device or an electric brake device. Each brake unit applies a braking force to the corresponding wheel in response to a command from the brake controller 9. Note that the brake unit need not be provided on all wheels.

Next, the configuration of the control system of the hybrid vehicle will be described.
As shown in FIG. 1, the control system of the hybrid vehicle includes an engine controller 1, a motor controller 2, an inverter 3, a battery 4, a first clutch controller 5, a first clutch hydraulic unit 6, and an AT controller. 7, a second clutch hydraulic unit 8, a brake controller 9, and an integrated controller 10. The engine controller 1, the motor controller 2, the first clutch controller 5, the AT controller 7, the brake controller 9, and the integrated controller 10 are connected via a CAN communication line 11 that can exchange information with each other. .

  The engine controller 1 inputs engine speed information from the engine speed sensor 12. Then, the engine controller 1 outputs a command for controlling the engine operating point (Ne, Te), for example, to a throttle valve actuator (not shown) in accordance with a target engine torque command or the like from the integrated controller 10. Information on the engine speed Ne is supplied to the integrated controller 10 via the CAN communication line 11.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor MG. Then, the motor controller 2 outputs a command for controlling the motor operating point (Nm, Tm) of the motor MG to the inverter 3 in response to the target motor torque command from the integrated controller 10 in accordance with the rotational speed command or the like. The motor controller 2 monitors the battery SOC indicating the state of charge of the battery 4, and the battery SOC information is used as control information for the motor MG and is supplied to the integrated controller 10 via the CAN communication line 11. .

  The first clutch controller 5 inputs sensor information from the first clutch oil pressure sensor 14 and the first clutch stroke sensor 15. The first clutch controller 5 gives a command for controlling the engagement / release of the first clutch CL1 in response to the first clutch control command (target first clutch transmission torque command) from the integrated controller 10. Output to. Information on the first clutch stroke C1S is supplied to the integrated controller 10 via the CAN communication line 11.

  The AT controller 7 inputs sensor information from the accelerator opening sensor 16, the vehicle speed sensor 17, and the second clutch hydraulic pressure sensor 18. Then, the AT controller 7 controls the engagement / disengagement of the second clutch CL2 in preference to the second clutch control in the shift control according to the second clutch control command (target second clutch torque command) from the integrated controller 10. Is output to the second clutch hydraulic unit 8 in the AT hydraulic control valve. Information on the accelerator opening AP and the vehicle speed VSP is supplied to the integrated controller 10 via the CAN communication line 11.

  The brake controller 9 inputs sensor information from a wheel speed sensor 19 and a brake stroke sensor 20 that detect the wheel speeds of the four wheels. The brake controller 9 calculates a target deceleration P0 based on the stroke amount of the brake pedal and the vehicle speed VSP in a predetermined control cycle. Then, a braking force command value is output to each brake unit so that deceleration corresponding to the target deceleration P0 occurs in the vehicle.

  The brake controller 9 performs regenerative cooperative brake control when, for example, when the brake is depressed, if the regenerative braking force is insufficient with respect to the required braking force obtained from the brake stroke BS. That is, regenerative cooperative brake control is performed based on a regenerative cooperative control command from the integrated controller 10 so that the shortage is compensated by mechanical braking force (hydraulic braking force or motor braking force).

  The integrated controller 10 manages the energy consumption of the entire vehicle and bears a function for running the vehicle with the highest efficiency. The integrated controller 10 includes a motor speed sensor 21 that detects a motor speed Nm, a second clutch output speed sensor 22 that detects a second clutch output speed N2out, and a second clutch that detects a second clutch torque. Information from the torque sensor 23 is input. Further, the integrated controller 10 inputs information acquired via the CAN communication line 11. Then, the integrated controller 10 executes operation control of the engine E according to a control command to the engine controller 1. The integrated controller 10 performs operation control of the motor MG in response to a control command to the motor controller 2. The integrated controller 10 executes engagement / disengagement control of the first clutch CL <b> 1 according to a control command to the first clutch controller 5. The integrated controller 10 executes the engagement / release control of the second clutch CL <b> 2 according to a control command to the AT controller 7.

Next, the basic operation mode in the hybrid vehicle of this embodiment will be described.
If the battery SOC is low while the vehicle is stopped, the engine E is started to generate electric power, and the battery 4 is charged. When the battery SOC is in the normal range, the first clutch CL1 is engaged and the second clutch CL2 is released, and the engine E is stopped.
When the engine starts, the motor MG is rotated according to the accelerator opening AP and the battery SOC state to switch to power running / power generation.
When the motor starts, when the output rotation of the automatic transmission AT becomes negative due to rollback, slip control of the second clutch CL2 is performed, and the rotation of the motor MG is maintained at the positive rotation. Next, the driving force is increased until the vehicle moves forward, and the second clutch CL2 is shifted from slip control to engagement.

Motor running secures motor torque and battery output necessary for starting the engine, and shifts to engine running if insufficient. Further, when the vehicle speed becomes equal to or higher than a predetermined vehicle speed, the motor travels to the engine travel. Further, when the engine is running, the motor MG assists the engine torque delay in order to improve the response when the accelerator is depressed. That is, while the engine is running, there is a mode in which only the engine power or the engine motor power is used.
At the time of brake-on deceleration, a deceleration force corresponding to the driver's brake operation is obtained by regenerative cooperative brake control.
At the time of shifting during engine traveling or motor traveling, the motor MG is regenerated / powered to adjust the rotational speed associated with the shifting during acceleration / deceleration to perform smooth shifting without a torque converter.

Next, a part related to the present invention in the braking / driving control process executed by the integrated controller 10 will be described.
As shown in FIG. 2, the integrated controller 10 includes a braking / driving control unit main body 10A, a target driving force calculation unit 10B, a motor travel control unit 10C, an engine travel control unit 10D, and a travel mode transition processing unit 10E. The integrated controller 10 also includes a braking control unit and other control units.

The braking / driving control unit main body 10A determines the state of the vehicle based on the input information (vehicle speed information, accelerator opening information, SOC information, etc.), the motor traveling control unit 10C, the engine traveling control unit 10D, and the traveling mode transition. The processing unit 10E is activated. The travel mode transition processing unit 10E includes an engine start control unit 40.
The target driving force calculation unit 10B calculates a target driving force based on the accelerator opening and the vehicle speed. Then, the target driving force calculation unit 10B distributes the target driving force to the target engine torque and the target motor torque according to the travel mode.

  The motor travel control unit 10C outputs a release command for the first clutch CL1 to the first clutch controller 5 and outputs a fastening command for the second clutch CL2 to the AT controller, thereby bringing the first clutch CL1 into a released state. At the same time, the second clutch CL2 is engaged. Further, the motor traveling control unit 10 </ b> C outputs a target motor torque command corresponding to the target motor torque to the motor controller 2.

The engine running control unit 10D outputs a target engine torque command corresponding to the target engine torque to the engine controller 1.
The travel mode transition processing unit 10E controls the first clutch CL1, the second clutch CL2, the motor MG, and the engine E at the time of transition between the modes.
The engine start control unit 40 starts the engine E while the motor is running and performs a transition process to the engine running mode.

Next, the process of the engine start control unit 40 will be described.
The engine start control unit 40 is activated when an engine start command is acquired during motor running. As shown in FIG. 3, the engine start control unit 40 includes a start control unit main body 40A and a learning correction unit 40B.
The processing of the start control unit main body 40A will be described with reference to FIG.

First, in step S100, it is determined whether or not there is a request for starting the engine E. If it is determined that there is an engine start request, the process proceeds to step S110.
In step S110, a target second clutch CL2 torque command for setting the second clutch CL2 to the target clutch transmission torque is output to the AT controller 7. However, when the correction amount T1 is set by the learning correction unit 40B, the target clutch transmission torque command TCL2 is offset by the correction amount T1 and the torque command that is increased or decreased is output to the AT controller 7.

The target second clutch transmission torque command TCL2 is a transmission torque command capable of transmitting a torque equivalent to the output torque before the engine starting process, and does not affect the output shaft torque even if the driving force output by the motor MG is increased. The range is not given.
Here, the AT controller 7 controls the second clutch hydraulic unit 8 so that the clutch hydraulic pressure according to the command is generated. The AT controller 7 may perform the increase correction or the decrease correction of the correction amount T1 set by the learning correction unit 40B.

In step S120, a command for increasing the motor voltage and controlling the rotational speed of the motor MG is output to the motor controller. The actual torque of motor MG is determined by the load acting on motor MG.
In step S130, a torque command is output to the first clutch controller 5 so that the torque transmission torque of the first clutch CL1 becomes the torque for engine cranking.

In step S140, when it is detected that the engine speed and the motor speed are synchronized, the process proceeds to step S150, and a command to completely engage the first clutch CL1 is output as the end of the cranking process. The synchronization determination of the first clutch CL1 is determined to be synchronized when a specified time elapses when the differential rotation between the actual motor rotation and the actual engine rotation is equal to or less than a specified value. The specified value sets a differential rotation corresponding to the response dead time when shifting from the first clutch torque control to the complete engagement.
Further, when it is detected in step S160 that the engine speed has become equal to or higher than the startable speed, an engine start command is output to the engine controller 1. Then return.

Next, the learning correction unit 40B will be described.
As shown in FIG. 5, the learning correction unit 40 </ b> B includes a slip state estimation unit 41 and a slip fastening torque correction unit 42.
The slip state estimation means 41 estimates the slip state of the second clutch CL2 during the cranking process.
The slip engagement torque correcting means 42 is based on the estimation by the slip condition estimating means 41 so that the actual clutch transmission torque of the second clutch CL2 in which the engine start control means is operating properly approaches the slip condition of the second clutch CL2. The clutch transmission torque of the second clutch CL2 is corrected with respect to the target clutch transmission torque command TCL2.

As shown in FIG. 5, the slip state estimation means 41 includes motor actual torque acquisition means 41A, torque correction amount calculation means 41B, slip amount detection means 41C, and rotation speed difference detection means 41D.
The motor actual torque acquisition unit 41A acquires the actual torque of the motor MG. The motor actual torque MG-RT is acquired by estimating the actual torque from the motor current.

  The torque correction amount calculation means 41B acquires the maximum value of the actual torque MG-RT of the motor MG based on the motor actual torque MG-RT acquired by the motor actual torque acquisition means 41A during the start of the engine E. When the torque correction amount calculating means 41B determines that the maximum value of the acquired actual torque MG-RT is smaller than the usable motor torque, the usable motor torque and the actual torque MG- of the motor MG are determined. A torque deviation amount ΔT, which is the difference between the maximum values of RT, is calculated.

The slip amount detection means 41C detects the rotational speed difference between the input shaft and the output shaft of the second clutch CL2. What is necessary is just to acquire the rotation speed of the input shaft of the said 2nd clutch CL2, and the output shaft with the rotation sensor provided in each axis | shaft.
The rotation speed difference detection means 41D detects the minimum value of the rotation speed difference of the second clutch CL2 during the start of the engine E.
Here, during the cranking process described above, the rotational speed control of the motor MG is started and a clutch transmission torque command is output to the first clutch CL1, and then the input shaft and the output shaft of the first clutch CL1 are synchronized. The period until.
Further, as shown in FIG. 5, the slip engagement torque correction means 42 includes a slip engagement torque increase correction means 42A and a slip engagement torque decrease correction means 42B.

When the torque deviation amount ΔT calculated by the torque correction amount calculation unit 41B is a positive value, the slip engagement torque increase correction unit 42A obtains a clutch increase correction amount that is a positive value equal to or less than the torque correction amount ΔT. For example, the clutch increase correction amount is obtained by multiplying the torque correction amount ΔT by a gain of 1 or less.
Then, the slip engagement torque increase correction means 42A corrects the actual clutch transmission torque of the second clutch CL2 in which the engine start control is in operation by an amount greater than the target clutch transmission torque command TCL2 by the clutch increase correction amount.

When the slip engagement torque reduction correction means 42B determines that the rotation speed difference ΔN detected by the rotation speed difference detection means 41D is equal to or less than the predetermined rotation speed ΔN0, the actual clutch transmission torque of the second clutch CL2 in which the engine start control means is operating is determined. Then, the predetermined clutch decrease correction amount is corrected to decrease from the target clutch transmission torque command TCL2.
The increase correction and decrease correction do not correct the target clutch transmission torque command TCL2 itself. The command output to the AT controller 7 is increased and decreased by the correction amount T1 learned with respect to the target clutch transmission torque command TCL2. Alternatively, the AT controller 7 may control the clutch hydraulic pressure by correcting the increase correction or the decrease correction.
However, correction processing is not performed in any of the following learning prohibition conditions.
Learning prohibition conditions:
・ When stopping by releasing the foot during start control ・ When releasing the second clutch CL2 by depressing during start control ・ When selecting during start control ・ When fail-safe is activated

Next, the processing of the learning processing unit will be described with reference to the flow shown in FIG.
Note that, as described above, the engine E operates during start-up control.
First, in step S210, it is determined whether the hydraulic pressure is not grasped by the second clutch CL2 during the cranking process or not. Other than that, there are a case where the response can be made according to the command and a case where the hydraulic pressure is excessively grasped.
Specifically, a torque deviation ΔT between the maximum value of the actual motor torque MG-RT during cranking and the usable motor torque is obtained, and it is determined whether or not the torque deviation ΔT is greater than zero. When the second clutch CL2 does not grasp the hydraulic pressure with respect to the command during cranking, the difference ΔT is greater than zero.

Here, the actual motor torque MG-RT is estimated from the current value of the motor MG as described above. The motor torque that can be used is the maximum usable torque that is determined based on the specifications of the motor, such as output limits such as rotation and temperature, and torque limits.
If the torque deviation ΔT is greater than zero, the process proceeds to step S220. When the torque deviation ΔT = 0, the process proceeds to step S300.
In step S220, it is determined whether or not the torque deviation ΔT is smaller than α. If the torque deviation ΔT is smaller than α, the process proceeds to step S230. If the torque deviation ΔT is greater than or equal to α, the process proceeds to step S240.

α is a single learning correction amount T1 (torque or hydraulic pressure). This α is set to a value (for example, 0.02 G or less) at which the driver does not feel the G change by one correction.
If the torque deviation ΔT is smaller than α, the correction amount is set to zero in step S230. When the second clutch CL2 is different for each gear position, a correction amount is set for each clutch.
When the torque deviation ΔT is greater than or equal to α, the offset is increased α relative to the target command torque TCL2 of the second clutch CL2 at the next engine start. Α is set to the correction amount T1 as the increase correction amount.

Here, the starting control unit body 40A is a command to + ArufaNm increase correction to the target second clutch transmission torque command TCL2, forces out to the AT controller 7. Alternatively, the AT controller 7 corrects the hydraulic pressure corresponding to + αNm in the hydraulic pressure command for the target second clutch transmission torque command TCL2.
If the second clutch CL2 is as commanded or overgrown, the process proceeds to step S300 to set a reduction correction amount that is offset with respect to the second clutch transmission torque command TCL2 at the next engine start.

That is, in step S300, it is determined whether or not the differential rotation ΔN (or gear ratio) of the second clutch CL2 during cranking is greater than the specified rotation.
When the differential rotation ΔN (or gear ratio) of the second clutch CL2 at the time of cranking> the specified rotation ΔN0, the process proceeds to step S310 and the offset amount is set to zero. That is, the reduction correction amount is set to zero.
When the differential rotation ΔN (or gear ratio) of the second clutch CL2 at the time of cranking ≦ the specified rotation ΔN0, the process proceeds to step S320.
In step S320, it is determined whether or not minimum value of differential rotation of second clutch CL2 ≧ specified value ΔN0.

When the minimum value of the differential rotation of the second clutch CL2 ≧ the specified value ΔN0, the process proceeds to step S330, and a single reduction correction amount is set to β (torque or hydraulic pressure). That is, −β is set as the correction amount T1. β is set in the same manner as the α setting method described above.
Further, if CL2 differential rotation minimum value <specified value, the process proceeds to step S340, and a single reduction correction amount is set to γ (torque or hydraulic pressure). That is, -γ is set as the correction amount T1.
When the second clutch CL2 is different for each gear position, correction amounts β and γ are set for each clutch.

Here, the specified value is set to zero or according to the responsiveness to disturbance of the rotational speed control of the motor MG.
Here, the start control unit main body 40A mainly gives the AT controller 7 a command that is corrected to decrease with respect to the target second clutch transmission torque command TCL2. Alternatively, the AT controller 7 reduces and corrects the hydraulic pressure corresponding to the reduction correction amount in the hydraulic pressure command for the target second clutch transmission torque command TCL2.

(Operation / Action)
In the hybrid vehicle as in the present embodiment, when the engine is started from a state where only the motor MG travels with a low accelerator opening, driving force control and start are performed only with the motor MG. For this reason, it is important that the second clutch CL2 is slip-engaged in order to control the driving force and cut off the input torque fluctuation. However, the second clutch CL2 has a large solid variation, and there is a possibility that the variation becomes large due to wear due to deterioration with time or a change in the oil amount.

Here, a case is considered in which the sum of the clutch transmission torque command values of the first clutch CL1 and the second clutch CL2 is the maximum motor torque value.
In this case, if the actual clutch transmission torque of the second clutch CL2 is grasped too much with respect to the command, the actual motor torque (maximum value) <(first clutch actual torque + second clutch actual torque). In this case, the slip engagement of the second clutch CL2 cannot be maintained, and the input torque fluctuation is transmitted to the output shaft to cause a shock.

On the other hand, when the actual clutch transmission torque of the second clutch CL2 is weak with respect to the command, the driving force at the start is low although the motor actual torque MG-RT is not used at the maximum torque, There is a delay.
This embodiment can solve this problem.
Here, from the viewpoint of fuel consumption, the motor travel area is expanded. For this reason, almost the maximum value is used as the motor torque when starting the engine. When there is a margin in the motor torque or when the system request is started due to a decrease in the SOC of the battery, excessive gripping of the second clutch CL2 can be compensated by the margin of the motor torque.

  The process premised on starting the engine of the present embodiment is to cut off the input torque fluctuation by maintaining the slip engagement state of the second clutch CL2. Here, the hybrid system of this embodiment has only one motor MG. For this reason, it is necessary to distribute the motor torque to the cranking torque of the engine via the first clutch CL1 and the driving torque of the second clutch CL2, and to maintain the clutch in a slip engagement state.

  A typical scene for starting the engine is a scene in which the driver depresses the accelerator pedal and requests driving force. Therefore, it is desirable that the motor torque can be ensured by using the maximum torque as much as possible. In order to cope with this, in the present embodiment, it is determined whether the second clutch CL2 is excessively gripping the hydraulic pressure with respect to the command at the time of cranking or not, that is, whether the slip is not appropriate. If the slip is not appropriate, an offset to the command of the second clutch CL2 at the next start is performed and corrected.

  Specifically, when the engine is started from a state where the accelerator travels only with the motor MG at a low opening, the actual motor torque MG-RT at the time of engine cranking by the first clutch CL1 is obtained. If ΔT, which is the difference between the actual motor torque MG-RT during cranking and the usable motor torque, is greater than zero, it is determined that the actual hydraulic pressure of the second clutch CL2 is smaller than the command. In this case, at the next engine start, the torque is offset by an amount equal to or smaller than ΔT to the increase side with respect to the command value of the clutch transmission torque of the second clutch CL2.

Here, the motor actual torque MG-RT is the total actual torque of the first clutch CL1 and the second clutch CL2. Further, as described above, the time of cranking is the time from when the rotational speed control of the motor MG is started and the first clutch CL1 is synchronized after the torque command of the first clutch CL1 is started.
Note that the torque of the first clutch CL1 can be estimated from a stroke sensor, an increase in engine rotation, or the like. For this reason, torque correction of the first clutch CL1 is separately performed.

  As described above, when the actual hydraulic pressure of the second clutch CL2 is small with respect to the command torque, it is corrected by offsetting to the increasing side at the next start. As a result, the second clutch CL2 can ensure a hydraulic pressure equivalent to the command torque in a state where the slip engagement state of the second clutch CL2 is maintained and the input torque fluctuation is cut off. That is, driving force can be secured. At this time, it is desirable that the actual motor torque MG-RT can be used as much as possible. Further, since the hydraulic pressure at the time of slip can be kept higher than the driving force before the second clutch CL2 is slipped, that is, the amount of hydraulic pressure released from the second clutch CL2 is smaller than at the time of the previous start, so the shock at the time of slip-in can be improved. . Further, since the hydraulic pressure of the second clutch CL2 is increased after the synchronization of the first clutch CL1, the second clutch CL2 hydraulic pressure at the time of cranking can be maintained corresponding to the command, so that the acceleration response can be accelerated.

Further, when the torque deviation ΔT of the usable motor torque is zero (= the actual motor torque MG-RT is limited to the usable motor torque), the following processing is performed.
If the second clutch CL2 differential rotation ΔN (or gear ratio) ≧ the specified rotation ΔN0 at the time of cranking, the actual hydraulic pressure of the second clutch CL2 can be almost secured with respect to the command. In this case, the next engine start Sometimes, no correction is made to the command value of the clutch transmission torque of the second clutch CL2.

  On the other hand, if the second clutch CL2 differential rotation ΔN (or gear ratio) during cranking is smaller than the specified rotation ΔN0, the actual hydraulic pressure of the second clutch CL2 is excessively grasped with respect to the command. In this case, the torque is offset to the decrease side with respect to the command value of the clutch transmission torque of the second clutch CL2 at the next engine start. The offset amount is set by the minimum value of the CL2 differential rotation ΔN during cranking.

  As described above, when the second clutch CL2 is larger than the command torque, the offset is corrected to the decreasing side at the next start. As a result, the actual motor torque MG-RT is maintained in a state where the usable torque is maximized as much as possible, and the slip of the second clutch CL2 can be maintained even if there is some disturbance. As a result, it is possible to secure a marginal torque (= torque that is restored when the actual rotation cannot maintain the target rotation due to a disturbance during motor rotation speed control) so that the input torque fluctuation can be cut off.

Here, in both the case where the second clutch CL2 is out of command and the case where the second clutch CL2 is gripping too much with respect to the command, the torque deviation ΔT between the motor actual torque MG-RT and the usable torque is Since they are the same, the next correction amount is determined using the differential rotation of the second clutch CL2.
FIG. 7 shows a time chart example of the present embodiment.
Here, the start control unit main body 40A constitutes an engine start control means. Steps S220 to S240 constitute the slip fastening torque increase correcting means 42A. Steps S300 to S340 constitute the slip fastening torque reduction correction means 42B.

(Effect of this embodiment)
(1) The engine start control means controls the rotational speed of the motor MG and slips the second clutch CL2 with the target clutch transmission torque command TCL2 when starting the engine E in a state where the engine MG is running only with the power of the motor MG. The cranking for engine starting is performed by controlling the engagement and controlling the engagement of the first clutch CL1 with a predetermined clutch transmission torque. The slip state estimation means 41 estimates the actual slip state of the second clutch CL2 during the cranking. Based on the estimation by the slip state estimating unit 41, the slip engagement torque correcting unit 42 is configured so that the clutch transmission torque of the second clutch CL2 in which the engine start control unit is operating is in a direction in which the slip state of the second clutch CL2 approaches appropriately. The clutch transmission torque of the second clutch CL2 is corrected with respect to the target clutch transmission torque command TCL2.
As a result, the slipping state of the second clutch CL2 at the time of cranking approaches appropriately. As a result, the slip engagement state of the second clutch CL2 can be maintained.

(2) When the torque correction amount calculating means 41B determines that the actual torque MG-RT of the motor MG during the cranking is smaller than the usable motor torque, the usable motor torque and the motor MG A torque deviation ΔT, which is a difference from the actual torque MG-RT, is calculated. The slip engagement torque increase correction means 42A is a clutch increase correction amount that is a positive value equal to or less than the torque deviation ΔT calculated by the torque correction amount calculation means 41B with respect to the clutch transmission torque of the second clutch CL2 in which the engine start control means is operating. The increase correction is made more than the target clutch transmission torque command TCL2 by T1.

That is, when the actual motor torque MG-RT during cranking and the torque deviation ΔT of the usable motor torque are greater than zero, the torque is increased ΔT toward the target clutch transmission torque command TCL2 of the second clutch CL2. Offset by the following torque T1.
The slip engagement state of the second clutch CL2 can be maintained by correcting the second clutch CL2 that is smaller than the command torque by offsetting it to the increase side.

(3) The rotational speed difference detecting means 41D detects the rotational speed difference of the second clutch CL2 during the cranking. When the slip engagement torque decrease correcting means 42B determines that the speed difference detected by the speed difference detecting means 41D is equal to or less than the predetermined speed, the slip transmission torque reduction correcting means 42B sets the clutch transmission torque of the second clutch CL2 in which the engine start control means is operating to a predetermined The amount is corrected to be smaller than the target clutch transmission torque command TCL2 by the clutch decrease correction amount.
That is, if the second clutch CL2 differential rotation ΔN (or gear ratio) at the time of cranking is less than the specified rotation ΔN0, the torque is offset to the decrease side with respect to the target clutch transmission torque command TCL2 of the second clutch CL2.
Accordingly, the slip of the second clutch CL2 can be maintained by correcting the second clutch CL2 that is smaller than the command torque by offsetting it to the increase side.

It is a figure explaining the system configuration | structure of the hybrid vehicle which concerns on embodiment based on this invention. It is a figure which shows the structure of the integrated controller which concerns on embodiment based on this invention. It is a figure which shows the structure of the engine starting control part which concerns on embodiment based on this invention. It is a figure explaining the process of the start-up control part main body which concerns on embodiment based on this invention. It is a figure which shows the structure of the learning correction | amendment part which concerns on embodiment based on this invention. It is a figure explaining the process of the learning correction | amendment part which concerns on embodiment based on this invention. It is an example of the time chart which concerns on embodiment based on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine controller 2 Motor controller 5 1st clutch controller 7 AT controller 10 Integrated controller 10A Braking / driving control part main body 10B Target driving force calculating part 10C Motor traveling control part 10D Engine traveling control part 10E Traveling mode transition process part 40 Engine start control part 40A Start control unit body 40B Learning correction unit 41 State estimation means 41A Motor actual torque acquisition means 41B Torque correction amount calculation means 41C Amount detection means 41D Speed difference detection means 42 Fastening torque correction means 42A Fastening torque increase correction means 42B Fastening torque decrease Correction means E Engine MG Motor MG Motor actual torque T1 Correction amount TCL2 Target clutch transmission torque command ΔN Speed difference ΔT Torque deviation

Claims (2)

A motor interposed in the torque transmission path from the engine to the driving wheel, a first clutch interposed in the torque transmission path between the engine and the motor, and a torque transmission path between the motor and the driving wheel. A vehicle engine start control device including a second clutch,
When the engine is started while running only with the power of the motor, the rotational speed of the motor is controlled, the second clutch is slip-engaged with a target clutch transmission torque command, and the first clutch is controlled with a predetermined clutch transmission torque. The engine start control means for performing cranking for engine start by controlling the fastening with
Slip state estimating means for estimating an actual slip state of the second clutch during the cranking;
Slip engagement torque correction means for correcting the clutch transmission torque of the second clutch with respect to the target clutch transmission torque command based on the estimation by the slip state estimation means;
With
The slip state estimating means includes
Motor actual torque acquisition means for acquiring the actual torque of the motor;
If it is determined that the actual torque of the motor during the cranking is smaller than the usable motor torque, a torque correction that calculates a torque deviation amount, which is a difference between the usable motor torque and the actual torque of the motor. A quantity calculation means;
A rotational speed difference detecting means for detecting a rotational speed difference between the input shaft and the output shaft of the second clutch during the cranking;
With
The slip fastening torque correction means is
The clutch transmission torque of the second clutch in which the engine start control means is operating is increased from the target clutch transmission torque command by an increase correction amount that is a positive value equal to or less than the torque deviation amount calculated by the torque correction amount calculation means. A slip fastening torque increase correcting means for correcting;
When it is determined that the rotational speed difference detected by the rotational speed difference detection means is equal to or less than the predetermined rotational speed, the target clutch transmission torque is set to the clutch transmission torque of the second clutch being operated by the engine start control means by a predetermined decrease correction amount. Slip fastening torque decrease correction means for correcting the decrease from the command,
An engine start control device comprising: An engine start control method for a vehicle in which a motor is connected to an engine via a first clutch, and the motor is connected to a drive wheel via a second clutch,
When the engine is started while running only with the power of the motor, the rotational speed of the motor is controlled, the second clutch is slip-engaged with a target clutch transmission torque command, and the first clutch is controlled with a predetermined clutch transmission torque. By controlling the tightening at, the engine is started by cranking while securing the traveling of the vehicle by the power of the motor,
Based on the estimation of the slipping state of the second clutch during cranking, the clutch transmission torque of the second clutch during engine start control is adjusted so that the slipping state of the second clutch approaches appropriately. Correct the clutch transmission torque with respect to the target clutch transmission torque command ,
The correction is
When it is determined that the actual torque of the motor during the cranking is smaller than the usable motor torque, a torque deviation amount that is a difference between the usable motor torque and the actual torque of the motor is calculated, and The clutch transmission torque of the second clutch is corrected to increase from the target clutch transmission torque command by an increase correction amount that is a positive value equal to or less than the calculated torque deviation amount.
When it is determined that the rotational speed difference between the input shaft and the output shaft of the second clutch during cranking is equal to or less than a predetermined rotational speed, the target clutch is set to a clutch transmission torque of the second clutch by a predetermined decrease correction amount. engine start control method characterized by decreasing correction than transfer torque command.

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