JP2010274788A - Control unit of power transmission device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control unit of a power transmission device for hybrid vehicle which shortens gear change time to improve drivability, when determination of gear change of a transmission is made during start processing of an engine. <P>SOLUTION: If gear change determination of an automatic transmission 22 is made during start processing of the engine, the oil pressure PB1 of a first brake B1 opened during gear change processing of the automatic transmission 22 is controlled to the oil pressure equivalent to the output torque Tmg2 of a second electric motor MG2. In this way, although control to exhaust oil pressure of the oil pressure PB1 is carried out, when start processing of an engine 24 ends, time to completely exhaust oil pressure of the oil pressure PB1 becomes shorter than usual, since the oil pressure PB1 is made the oil pressure equivalent to the output torque Tmg2 of the second electric motor MG2. Consequently, time of gear change is shortened and the drivability improves. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for a power transmission device for a hybrid vehicle, and more particularly to control when a shift determination is made during engine start control.

  2. Description of the Related Art A hybrid vehicle power transmission device including a transmission in a power transmission path between an electric motor and drive wheels is well known. In the vehicle power transmission device as described above, the driving force (torque) output from the electric motor can be amplified and transmitted to the driving wheels via the transmission. For example, an automatic transmission having a hydraulic friction engagement device controlled by hydraulic pressure is used as the transmission, and the speed is appropriately changed according to the running state of the vehicle. For example, when starting the vehicle, the driving force is increased by shifting the transmission to the low speed side, and then the vehicle speed is increased to shift the transmission to the high speed side to reduce the rotational speed of the electric motor. Suppresses high rotation of the motor. By controlling as described above, the drive efficiency of the electric motor can be maintained in a good state. For example, the control apparatus of the hybrid drive apparatus of patent document 1 is the example. In Patent Document 1, a two-speed transmission (6) is interposed between the second motor / generator (MG2) and the output shaft (2) connected to the drive wheel, so that the running state The transmission (6) is configured to change gears accordingly. Further, in Patent Document 1, even if a shift determination of the transmission is made during engine startup, by limiting (prohibiting) the shift, torque fluctuation or torque reduction transmitted to the output shaft is suppressed, and the engine A technique for reliably or smoothly starting the engine is disclosed.

JP 2006-306393 A JP 2004-203219 A

  By the way, even if the shift determination is made during the engine start process in Patent Document 1, the shift is limited (prohibited) until the engine start process ends. However, the shift control is started after the engine start process ends, and the transmission When the release side hydraulic pressure of the release side frictional engagement element released at the time of shifting is controlled (exhaust pressure), it takes time to completely release the release side hydraulic pressure, and the shift time becomes longer. was there. More specifically, when a shift determination is made during the engine start process, the shift process is restricted (prohibited), and control is performed in the order of the engine start process and the shift process. Therefore, the power transmission state of the transmission is maintained, and the reaction torque required when starting the engine is transmitted from the motor torque (MG2) via the transmission. As a result, the engine speed is increased to a rotational speed at which ignition can be performed, and the engine start process ends. Then, the shift process based on the shift determination is performed, but since the shift process is started while the release side hydraulic pressure remains at the normal engagement pressure, it takes time to completely release the release side hydraulic pressure. As a result, the drivability decreases, such as slack during acceleration.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to shorten the shift time and improve the drivability when the shift determination of the transmission is made during the engine starting process. An object of the present invention is to provide a control device for a power transmission device for a hybrid vehicle that can be improved.

  In order to achieve the above object, the gist of the invention according to claim 1 is that: (a) a differential mechanism that is connected to an engine so that power can be transmitted and the differential state is electrically controlled; And an electric motor connected to the output shaft of the moving mechanism via a transmission so that power can be transmitted. When the engine is started, the rotational speed of the engine is set with a reaction torque generated by the electric motor. In the control device for a hybrid vehicle power transmission device in which the engine start process for raising the engine speed to an ignition speed is performed, (b) when the shift determination of the transmission is made during the engine start process, The opening side hydraulic pressure of the opening side frictional engagement device that is released at the time of shifting is controlled to a hydraulic pressure corresponding to the output torque of the electric motor.

  The gist of the invention according to claim 2 for achieving the above object is that: (a) a differential mechanism that is connected to an engine so that power can be transmitted and the differential state is electrically controlled; A motor connected to the output shaft of the differential mechanism through a transmission so that power can be transmitted, and when the engine is started, the rotational speed of the engine is generated in a state where reaction torque is generated by the motor. In a control device for a hybrid vehicle power transmission device in which an engine start process for raising the engine speed to an ignitable rotational speed is performed, (b) when the shift determination of the transmission is made during the engine start process, the transmission The opening side hydraulic pressure of the opening side frictional engagement device released at the time of shifting is controlled to a hydraulic pressure corresponding to the maximum torque of the electric motor required for starting the engine.

  According to a third aspect of the present invention, there is provided a control device for a hybrid vehicle power transmission device according to the first or second aspect, wherein the differential mechanism comprises a single pinion type planetary gear device, and a sun gear. Is connected to the differential motor, the carrier is connected to the engine so as to be able to transmit power, and the ring gear is connected to the output shaft.

  According to a fourth aspect of the present invention, there is provided a control device for a hybrid vehicle power transmission device according to the third aspect, wherein the open side frictional engagement device is opened when the transmission is shifted. In this state, rotation synchronization control is performed in which the rotation speed of the electric motor is synchronized with a target rotation speed set after shifting.

  According to the control device for a hybrid vehicle power transmission device of the first aspect of the present invention, when the shift determination of the transmission is made during the engine start process, the open side is opened when the transmission is shifted. The opening side hydraulic pressure of the friction engagement device is controlled to a hydraulic pressure corresponding to the output torque of the electric motor. In this way, the reaction torque generated by the electric motor, which is required when starting the engine, is transmitted to the differential mechanism via the transmission, so that the engine starting process is suitably performed. When the engine start process is completed, control is performed to discharge the hydraulic pressure of the open side hydraulic pressure. However, since the open side hydraulic pressure is the hydraulic pressure corresponding to the output torque of the electric motor, it is lower than the normal hydraulic pressure. Therefore, the time during which the open side hydraulic pressure is completely discharged becomes shorter than usual. Therefore, the shift time is shortened and drivability is improved.

  According to the control device for a hybrid vehicle power transmission device of the second aspect of the present invention, when the shift determination of the transmission is made during the engine starting process, the transmission is released at the time of the shift of the transmission. The opening side hydraulic pressure of the opening side frictional engagement device is controlled to a hydraulic pressure corresponding to the maximum torque of the motor required for starting the engine. In this way, the reaction torque generated by the electric motor, which is required when starting the engine, is transmitted to the differential mechanism via the transmission, so that the engine starting process is suitably performed. When the engine start process is completed, control is performed to release the hydraulic pressure of the open side hydraulic pressure. However, since the open side hydraulic pressure is the hydraulic pressure corresponding to the maximum torque of the motor required for starting the engine, The pressure is lower than the hydraulic pressure, and the time for releasing the hydraulic pressure of the opening side hydraulic pressure is shorter than usual. Therefore, the shift time is shortened and drivability is improved. In addition, since the open side hydraulic pressure is the hydraulic pressure that corresponds to the maximum torque of the motor required for starting the engine, it is reliably prevented that the torque of the motor exceeds the torque that can be transmitted by the transmission. It is possible to prevent a shock from occurring due to a change to an unintended rotational speed.

  According to a control device for a hybrid vehicle power transmission device of a third aspect of the invention, the differential mechanism is constituted by a single pinion type planetary gear device, a sun gear is connected to the differential motor, and the carrier Is connected to the engine so as to be able to transmit power, and a ring gear is connected to the output shaft, so that the differential motor is rotated and lifted, and the reaction torque of the motor is transmitted to the ring gear. The engine connected to the carrier is rotated and raised by the differential action of the moving mechanism. Therefore, the rotation of the engine can be increased to the ignition speed so that the engine can be started.

  According to the control device for a hybrid vehicle power transmission device of a fourth aspect of the present invention, when the transmission is shifted, the rotation of the electric motor is performed with the open side frictional engagement device open. Since the rotation synchronization control is performed to synchronize the speed with the target rotation speed set after the shift, the shift time becomes shorter when the time until the release-side hydraulic pressure is completely released and the release-side frictional engagement device is released is shortened. Shorter. Therefore, since the shift is started from the state in which the open side hydraulic pressure is lower than normal according to the present invention, the shift time is shortened as the time until the open side hydraulic pressure is completely removed is shortened.

It is a schematic block diagram explaining the power transmission device for hybrid vehicles to which this invention was applied. It is a collinear diagram showing the relative relationship of the rotational speed of each rotation element of the planetary gear set that functions as a power distribution mechanism. It is a collinear chart for expressing the relative relationship of each rotation element about the Ravigneaux type planetary gear mechanism which comprises an automatic transmission. It is a functional block diagram explaining the principal part of the control function of an electronic controller. It is an alignment chart which shows the rotation state of each rotation element of the planetary gear apparatus at the time of implementing engine start control (engine start process). It is a shift diagram which determines the shift of an automatic transmission from the relationship memorize | stored beforehand. 7 is a flowchart for explaining a control operation for improving drivability by shortening a shift time when a shift of the automatic transmission is determined during a main control operation of the electronic control unit, that is, engine start control. It is a time chart explaining the operating state by an electronic control unit when the shift of an automatic transmission is judged during engine starting control. FIG. 5 is another flowchart for explaining the control operation for improving the drivability by shortening the shift time when the shift of the automatic transmission is judged during the main part of the control operation of the electronic control unit, that is, the engine start control. is there. FIG. 10 is another time chart for explaining an operation state by the electronic control unit when a shift of the automatic transmission is determined during engine start control, and corresponds to the flowchart of FIG. 9.

  Here, preferably, the hydraulic pressure corresponding to the output torque of the electric motor is a hydraulic pressure that secures a torque capacity that allows the output torque of the electric motor to be transmitted to the differential mechanism, and is obtained in advance through experiments and calculations. It is set based on a relationship map of hydraulic pressure with respect to torque. If it does in this way, open side oil pressure will be set up according to the output torque of an electric motor, and the output torque of an electric motor will be transmitted to a differential mechanism via a transmission.

  Preferably, the hydraulic pressure corresponding to the maximum torque of the electric motor required for starting the engine is a hydraulic pressure capable of transmitting the maximum torque of the electric motor required for starting the engine that changes according to the running state of the vehicle, It is obtained and stored in advance by experiments and calculations. In this way, since the output torque of the motor does not exceed the torque capacity allowed by the open side frictional engagement device, a shock may occur due to a change in the rotation speed of the motor to an unintended rotation speed. Is prevented.

  Preferably, the rotation synchronous control by the electric motor means that the input shaft of the transmission is controlled by the electric motor connected to the input shaft of the transmission in a state where the open side hydraulic pressure of the open side frictional engagement device is completely removed. Is controlled so as to become the synchronous rotational speed set after the shift or the target rotational speed set based on the synchronous rotational speed. In this way, the shock that occurs when the engagement-side frictional engagement device is engaged is suppressed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a schematic configuration diagram illustrating a hybrid vehicle power transmission device 10 (hereinafter referred to as a vehicle power transmission device 10) to which the present invention is applied. In FIG. 1, in the vehicle power transmission device 10, torque of a first drive source 12 that is a main drive source is transmitted to a wheel side output shaft (hereinafter referred to as an output shaft) 14 that functions as an output member in the vehicle. Torque is transmitted from the output shaft 14 (corresponding to the output shaft of the present invention) to the pair of left and right drive wheels 18 via the differential gear device 16. Further, the vehicle power transmission device 10 includes a second electric motor MG2 capable of selectively executing power running control for outputting driving force for traveling and regenerative control for recovering energy. The power transmission is connected to the output shaft 14 via a transmission). Therefore, the output torque transmitted from the second electric motor MG2 to the output shaft 14 depends on the speed ratio γs (= the rotational speed Nmg2 of the second electric motor MG2 / the rotational speed Nout of the output shaft 14) set by the automatic transmission 22. It is designed to increase or decrease.

  The automatic transmission 22 interposed in the power transmission path between the second motor MG2 (corresponding to the motor of the present invention) and the output shaft 14 (drive wheels 18) has a plurality of gear ratios γs larger than “1”. The second motor MG2 has a lower capacity because the torque can be increased and transmitted to the output shaft 14 during powering to output torque from the second motor MG2. Or it is small. Thus, for example, when the rotational speed Nout of the output shaft 14 increases with a high vehicle speed, the second motor is reduced by reducing the speed ratio γs in order to maintain the operating efficiency of the second motor MG2. When the rotational speed of the MG2 (hereinafter referred to as the second motor rotational speed) Nmg2 is decreased or the rotational speed Nout of the output shaft 14 is decreased, the gear ratio γs is increased and the second motor rotational speed Nmg2 is increased. Let

  The first drive source 12 synthesizes torque between the engine 24 as the main power source, the first electric motor MG1, and the engine 24 and the first electric motor MG1 (corresponding to the differential electric motor of the present invention) or A planetary gear unit 26 as a power distribution mechanism (differential mechanism) for distributing is mainly configured. The engine 24 is a known internal combustion engine that outputs power by burning fuel such as a gasoline engine or a diesel engine, and an engine control electronic control unit (E-ECU) 28 mainly composed of a microcomputer The operation state such as the throttle valve opening, the intake air amount, the fuel supply amount, and the ignition timing is electrically controlled.

  The first electric motor MG1 (differential electric motor) is, for example, a synchronous motor, and is configured to selectively generate a function as a motor that generates a drive torque and a function as a generator. Connected to a power storage device 32 such as a battery or a capacitor. The inverter 30 is controlled by an electronic control unit (MG-ECU) 28 for controlling the motor generator mainly composed of a microcomputer so that the output torque or regenerative torque of the first electric motor MG1 is adjusted or set. It has become.

  The planetary gear device 26 (corresponding to the differential mechanism of the present invention) rotates the sun gear S0, the ring gear R0 arranged concentrically with the sun gear S0, and the pinion gear P0 meshing with the sun gear S0 and the ring gear R0. This is a single-pinion type planetary gear mechanism that includes a carrier CA0 that is supported so as to revolve freely as three rotating elements, and that generates a known differential action. The planetary gear device 26 is provided concentrically with the engine 24 and the automatic transmission 22. Since the planetary gear device 26 and the automatic transmission 22 are configured symmetrically with respect to the center line, the lower half of them is omitted in FIG.

  In the present embodiment, the crankshaft 36 of the engine 24 is connected to the carrier CA0 of the planetary gear device 26 via a damper 38. On the other hand, the first motor MG1 is connected to the sun gear S0, and the output shaft 14 is connected to the ring gear R0. The carrier CA0 functions as an input element, the sun gear S0 functions as a reaction force element, and the ring gear R0 functions as an output element.

  The relative relationship between the rotational speeds of the rotating elements of the single pinion type planetary gear device 26 functioning as a differential mechanism is shown by the alignment chart of FIG. In this alignment chart, the vertical axis S0, the vertical axis CA0, and the vertical axis R0 are axes respectively representing the rotational speed of the sun gear S0, the rotational speed of the carrier CA0, and the rotational speed of the ring gear R0. The distance between the axis CA0 and the vertical axis R0 is 1 when the distance between the vertical axis S0 and the vertical axis CA0 is 1. The distance between the vertical axis CA0 and the vertical axis R0 is ρ (the number of teeth Zs of the sun gear S0 / ring gear). R0 is set to be the number of teeth Zr).

  In the planetary gear unit 26, when the reaction torque generated by the first electric motor MG1 is input to the sun gear S0 with respect to the output torque of the engine 24 input to the carrier CA0, the ring gear R0 serving as an output element Since direct torque appears, the first electric motor MG1 functions as a generator. Further, when the rotational speed of the ring gear R0, that is, the rotational speed of the output shaft 14 (output shaft rotational speed) Nout is constant, the rotational speed of the engine 24 (engine speed) is changed by changing the rotational speed Nmg1 of the first electric motor MG1 up and down. The rotational speed Ne can be changed continuously (steplessly). The broken line in FIG. 2 shows a state where the engine rotational speed Ne decreases when the rotational speed Nmg1 of the first electric motor MG1 is lowered from the value shown by the solid line. That is, the control for setting the engine rotation speed Ne to, for example, the rotation speed with the best fuel efficiency can be executed by controlling the first electric motor MG1. This type of hybrid type is called mechanical distribution type or split type. From the above, the differential state of the planetary gear device 26 is electrically controlled by the first electric motor MG1.

  Returning to FIG. 1, the automatic transmission 22 includes a set of Ravigneaux planetary gear mechanisms. That is, the automatic transmission 22 is provided with a first sun gear S1 and a second sun gear S2. The large diameter portion of the stepped pinion P1 meshes with the first sun gear S1, and the stepped pinion P1 is pinned by the pinion P2. And the pinion P2 meshes with a ring gear R1 (R2) disposed concentrically with the sun gears S1 and S2. Each of the pinions P1 and P2 is held by a common carrier CA1 (CA2) so as to rotate and revolve. Further, the second sun gear S2 meshes with the pinion P2.

  The second electric motor MG2 is controlled by an electronic control unit (MG-ECU) 28 for controlling the motor generator via an inverter 40, thereby functioning as an electric motor or a generator, and assist output torque or regenerative torque. Is adjusted or set. The second electric motor MG2 is connected to the second sun gear S2, and the carrier CA1 is connected to the output shaft 14. The first sun gear S1 and the ring gear R1 constitute a mechanism corresponding to a double pinion type planetary gear device together with the pinions P1 and P2, and the second sun gear S2 and the ring gear R1 together with the pinion P2 constitute a single pinion type planetary gear device. The mechanism equivalent to is comprised.

  The automatic transmission 22 includes a first brake B1 provided between the first sun gear S1 and the housing 42, which is a non-rotating member, and a ring gear R1 in order to selectively fix the first sun gear S1. A second brake B2 provided between the ring gear R1 and the housing 42 is provided for selective fixing. These brakes B1 and B2 are so-called friction engagement devices that generate a braking force by a frictional force, and a multi-plate type engagement device or a band type engagement device can be adopted. These brakes B1 and B2 are configured such that their torque capacities change continuously according to the engagement pressure generated by the brake B1 hydraulic actuator such as a hydraulic cylinder and the brake B2 hydraulic actuator, respectively. Yes.

  In the automatic transmission 22 configured as described above, when the second sun gear S2 functions as an input element, the carrier CA1 functions as an output element, and the first brake B1 is engaged, the shift is greater than “1”. When the high speed stage Hi with the ratio γsh is established and the second brake B2 is engaged instead of the first brake B1, the low speed stage Lo with the speed ratio γsl larger than the speed ratio γsh of the high speed stage Hi is established. It is configured. That is, the automatic transmission 22 is a two-stage transmission, and the shift between these shift stages H and L is executed based on the running state such as the vehicle speed V and the required driving force (or accelerator operation amount). More specifically, the shift speed region is determined in advance as a map (shift diagram), and control is performed so as to set one of the shift speeds according to the detected driving state. An electronic control unit (T-ECU) 28 for speed change control mainly including a microcomputer for performing the control is provided.

  The electronic control device 28 is, for example, an engine control electronic control device (E-ECU) for controlling the engine 24, and an MG control electronic control device (MG-) for controlling the first electric motor MG1 and the second electric motor MG2. ECU) and a shift control electronic control unit (T-ECU) for controlling the automatic transmission 22. The electronic control unit 28 includes a signal representing the first motor rotational speed Nmg1 from the first motor rotational speed sensor 41, a signal representing the second motor rotational speed Nmg2 from the second motor rotational speed sensor 43, and an output shaft rotational speed sensor. 45, a signal representing the output shaft rotational speed Nout corresponding to the vehicle speed V from 45, a signal representing the hydraulic pressure PB1 of the first brake B1 from the hydraulic switch signal SW1, and a signal representing the hydraulic pressure PB2 of the second brake B2 from the hydraulic switch SW2. A signal indicating the operation position of the shift lever 35 from the operation position sensor SS, a signal indicating the operation amount of the accelerator pedal 27 from the accelerator operation amount sensor AS, a signal indicating whether or not the brake pedal 29 is operated from the brake sensor BS, and the like. Supplied. In addition, from a sensor (not shown) or the like, a signal indicating the charging current or discharging current (hereinafter referred to as charging / discharging current or input / output current) Icd of the power storage device 32, a signal indicating the voltage Vbat of the power storage device 32, the charging capacity of the power storage device 32 (Charge state) A signal representing SOC, a signal representing the output torque Tmg1 or regenerative torque of the first motor MG1 based on the supply power (supply current) of the inverter 30, and a second motor MG2 based on the supply power (supply current) of the inverter 40 Output torque Tmg2 or a signal representing the regenerative torque is supplied. The engine control electronic control unit (E-ECU), the MG control electronic control unit (MG-ECU), and the shift control electronic control unit (T-ECU) are not necessarily configured separately. You may be comprised integrally.

  3 shows four vertical axes S1, vertical axes R1, vertical axes CA1, and vertical axes S2 in order to show the mutual relationship of the rotating elements of the Ravigneaux type planetary gear mechanism constituting the automatic transmission 22. The collinear diagram which has is shown. The vertical axis S1, the vertical axis R1, the vertical axis CA1, and the vertical axis S2 indicate the rotation speed of the first sun gear S1, the rotation speed of the ring gear R1, the rotation speed of the carrier CA1, and the rotation speed of the second sun gear S2, respectively. Is for.

  In the automatic transmission 22 configured as described above, when the ring gear R1 is fixed by the second brake B2, the low speed stage Lo is set, and the assist torque output by the second electric motor MG2 becomes the speed ratio γsl at that time. Accordingly, the signal is amplified and added to the output shaft 14. Instead, when the first sun gear S1 is fixed by the first brake B1, the high speed stage Hi having a speed ratio γsh smaller than the speed ratio γsl of the low speed stage Lo is set. Since the gear ratio γsh at the high speed Hi is also larger than “1”, the assist torque output from the second electric motor MG2 is increased according to the gear ratio γsh and added to the output shaft 14.

  Note that, in a state where the gears L and H are constantly set, the torque applied to the output shaft 14 is a torque obtained by increasing the output torque Tmg2 of the second electric motor MG2 in accordance with each gear ratio. However, in the shift transition state of the automatic transmission 22, the torque is influenced by the torque capacity at each brake B1, B2 and the inertia torque accompanying the change in the rotational speed. Further, the torque applied to the output shaft 14 becomes positive torque when the second electric motor MG2 is driven, and becomes negative torque when the second electric motor MG2 is driven. The driven state of the second electric motor MG2 is a state in which the rotation of the output shaft 14 is transmitted to the second electric motor MG2 via the automatic transmission 22 so that the second electric motor MG2 is rotationally driven. It does not necessarily coincide with driving and driven.

  FIG. 4 is a functional block diagram illustrating the main part of the control function of the electronic control unit 28. In FIG. 4, for example, when the control is started by operating the power switch while the brake pedal is operated after the key is inserted into the key slot, the hybrid drive control means 60 increases the accelerator operation amount. Based on this, the required output of the driver is calculated, and the required output is generated from the engine 24 and / or the second electric motor MG2 so as to achieve a low fuel consumption and low exhaust gas operation. For example, a motor travel mode in which the engine 24 is stopped and the second electric motor MG2 is exclusively used as a drive source, a charge travel mode in which the first electric motor MG1 generates power by the power of the engine 24 and travels using the second electric motor MG2 as a drive source, an engine The engine running mode in which the motive power of 24 is mechanically transmitted to the drive wheels 18 is switched in accordance with the running state.

  The hybrid drive control means 60 controls the engine rotational speed Ne by the first electric motor MG1 so that the engine 24 operates on the optimum fuel consumption curve. Further, when torque assist is performed by driving the second electric motor MG2, when the vehicle speed V is low, the automatic transmission 22 is set to the low speed stage Lo, the torque applied to the output shaft 14 is increased, and the vehicle speed V is increased. Then, the automatic transmission 22 is set to the high speed stage Hi, the second motor rotational speed Nmg2 is relatively lowered to reduce the loss, and efficient torque assist is executed. Further, during coasting, the first electric motor MG1 or the second electric motor MG2 is rotated by the inertial energy of the vehicle to regenerate electric power, and the electric power is stored in the power storage device 32.

  The reverse travel is achieved, for example, by rotationally driving the second electric motor MG2 in the reverse direction with the automatic transmission 22 in the low speed stage Lo. At this time, the first electric motor MG1 of the first drive source 12 is in an idling state, and the output shaft 14 is allowed to reversely rotate regardless of the operating state of the engine 24.

  More specifically, the control in the engine travel mode will be described as an example. The hybrid drive control means 60 operates the engine 24 in an efficient operating range in order to improve power performance, fuel consumption, and the like. Control is performed so as to optimize the distribution of the driving force with the second electric motor MG2 and the reaction force generated by the power generation of the first electric motor MG1.

  For example, the hybrid drive control means 60 determines a target drive force-related value such as a required output shaft torque TR (required for the required drive torque) based on the accelerator operation amount or the vehicle speed as the driver's required output amount from a previously stored drive force map. The required output shaft power is calculated from the required output shaft torque TR in consideration of the required output shaft torque TR, and the transmission loss, auxiliary load, and second motor MG2 are calculated so that the required output shaft power can be obtained. The target engine power is calculated in consideration of the assist torque of the automatic transmission 22 and the shift stage of the automatic transmission 22, and so on, for example, so as to achieve both drivability and fuel efficiency in the two-dimensional coordinates composed of the engine rotation speed and the engine torque. The target engine performance is calculated while operating the engine 24 in accordance with an engine optimum fuel consumption rate curve (fuel consumption map, relationship) which is experimentally obtained and stored in advance. As the engine rotational speed and the engine torque over is obtained, it controls the power generation amount of the first electric motor MG1 controls the engine 24.

  The hybrid drive control means 60 supplies the electric energy generated by the first electric motor MG1 to the power storage device 32 and the second electric motor MG2 through the inverters 30 and 40, so that the main part of the power of the engine 24 is mechanically the output shaft 14. However, a part of the motive power of the engine 24 is consumed for power generation of the first electric motor MG1 and converted there into electric energy, and the electric energy is supplied to the second electric motor MG2 through the inverters 30 and 40, The second electric motor MG2 is driven and transmitted from the second electric motor MG2 to the output shaft 14. An electric path from conversion of a part of the power of the engine 24 into electric energy and conversion of the electric energy into mechanical energy by a device related from the generation of the electric energy to consumption by the second electric motor MG2 is obtained. Composed. The hybrid drive control means 60 can supply electric energy from the power storage device 32 directly to the second electric motor MG2 via the inverter 40 in addition to the electric energy by the electric path to drive the second electric motor MG2. Is possible.

  Further, the hybrid drive control means 60 controls the first electric motor MG1 by the differential action of the planetary gear unit 26 regardless of whether the vehicle is stopped or traveling, so that the engine rotation speed is maintained substantially constant or arbitrary rotation is achieved. The rotation is controlled to the speed. In other words, the hybrid drive control means 60 can control the rotation of the first electric motor MG1 to an arbitrary rotational speed while maintaining the engine rotational speed substantially constant or controlling it to an arbitrary rotational speed.

  Further, the hybrid drive control means 60 controls the fuel injection amount and the injection timing by the fuel injection device for the fuel injection control in addition to controlling the opening and closing of the electronic throttle valve by the throttle actuator for the throttle control. Therefore, an engine output for executing output control of the engine 24 so as to generate a necessary engine output by outputting a command for controlling the ignition timing by an ignition device such as an igniter alone or in combination to an engine output control device (not shown). Control means is functionally provided.

  The engine start control means 62 performs switching from the motor travel mode by the second electric motor MG2 to the engine travel mode by the engine 24 based on, for example, a travel mode switching map (not shown) for switching the vehicle travel mode set in advance. If it judges, when the rotational speed Ne of the engine 24 will be electrically pulled up by control of the 1st electric motor MG1 and the 2nd electric motor MG2, and the engine rotational speed Ne will raise to the preset ignition possible rotational speed Nig, it will depend on fuel injection apparatus. An engine start process for starting the engine 24 is performed by performing fuel injection control and performing ignition timing control by an ignition device. The travel mode switching map is composed of a two-dimensional map including, for example, the vehicle speed V and the accelerator opening Acc corresponding to the operation amount of the accelerator pedal 27. Based on the above, the travel mode switching map is based on the motor travel region by the second motor MG2 and the engine 24. It is divided into the engine running area. For example, in the relatively low vehicle speed and low driving force region (low accelerator opening region), the motor traveling region is used. In the middle / high vehicle speed and medium / high driving force region (medium / high accelerator opening region), the engine traveling region is used. It is an area.

Therefore, for example, when the vehicle starts or when the vehicle is lightly loaded, when the motor is driven by the second electric motor M2 and the vehicle is accelerated from that state, the motor drive mode is switched to the engine drive mode. In such a case, an engine start process by the engine start control means 62 is performed. Further, when the charge capacity SOC of the power storage device 32 falls below a preset lower limit capacity, the engine start control means 62 performs the start process of the engine 24 even if the current travel state is within the motor travel mode region. To do.

  FIG. 5 is a collinear diagram showing the rotation state of each rotating element of the planetary gear device 26 when the engine start control (engine start process) by the engine start control means 62 is performed. The basic configuration of the alignment chart of FIG. 5 is the same as that of the alignment chart of FIG. Here, the solid line indicates the rotation state during motor travel by the second electric motor MG2. When driven by the second electric motor MG2, the rotation of the second electric motor MG2 is decelerated via the automatic transmission 22 and transmitted to the output shaft 14. Therefore, the output shaft 14 (ring gear R0) is driven to rotate. Then, the engine 24 (CA0) is maintained at zero rotation by causing the first electric motor MG1 (sun gear S0) to be in a no-load state and reversely rotating (negatively rotating). When the engine start process is started in this state, as shown by the broken line, the first electric motor MG1 is driven to rotate in the positive direction while the rotation of the output shaft 14 (ring gear R0) is maintained. Accordingly, the rotational speed of the carrier CA0, that is, the engine rotational speed Ne is increased by the differential action of the planetary gear unit 26. Then, when the engine rotation speed Ne is increased to the ignition possible rotation speed Nig, the engine 24 is started by performing the fuel injection control and the ignition timing control of the engine 24. Here, when the engine speed is increased by the first electric motor MG1, a reaction torque for maintaining the rotation speed of the output shaft 14 is transmitted from the second electric motor MG2. The reaction torque generated from the second electric motor MG2 is transmitted from the output shaft 14 to the planetary gear unit 26 (ring gear R0), so that the engine rotation speed Ne can be increased by the first electric motor MG1. Note that the magnitude of the reaction torque is controlled by the output torque Tmg2 of the second electric motor MG2 so that, for example, the rotation speed Nout of the output shaft 14 does not change. Therefore, when starting the engine 24, the first motor MG1 and the second motor MG2 are controlled to increase the engine rotational speed Ne. When the reaction torque is transmitted to the planetary gear device 26 by the second electric motor MG2, the automatic transmission 22 is set in the power transmission state, so that the second electric motor MG2 transfers to the planetary gear device 26 (ring gear R0). Power transmission is possible.

  The speed change control means 66, for example, from the pre-stored shift diagram (shift map) shown in FIG. 6, the output shaft rotational speed Nout corresponding to the vehicle speed V and the required driving force (for example, the accelerator operation from the pre-stored driving force map). The shift of the automatic transmission 22 is determined based on the required output shaft torque TR corresponding to the target drive force determined by the hybrid drive control means 60 based on the amount, vehicle speed, etc., and determined based on the determination result. Shift processing for controlling the first brake B1 and the second brake B2 is performed so as to switch to the gear position. In FIG. 6, the solid line is an upshift line (up line) for switching from the low speed stage Lo to the high speed stage Hi, and the alternate long and short dash line is a downshift line (down line) for switching from the high speed stage Hi to the low speed stage Lo. And a predetermined shift is provided between the downshift. Shift lines indicated by these solid lines and alternate long and short dash lines correspond to shift rules, and shifts are performed according to these shift lines. That is, the shift control means 66 functionally includes a shift determination means for determining the shift of the automatic transmission 22 based on the shift diagram shown in FIG.

  The shift control means 66 outputs a shift command for switching to the determined shift stage to the hydraulic control circuit 50 of the automatic transmission 22. The hydraulic control circuit 50 switches the respective operating states of the first brake B1 and the second brake B2 by driving a linear solenoid valve provided in a hydraulic control circuit (not shown) according to the shift command.

  For example, when the vehicle travels through the upshift line during traveling at the low speed Lo (second brake B2 engagement), the second brake B2 is released and the first brake B1 is engaged. Control is implemented. Further, when the vehicle is traveling at the high speed Hi (first brake engagement) and the vehicle travels through the downshift line, the first brake B1 is released and the second brake B2 is engaged. Is implemented.

  When the accelerator pedal 27 is depressed and the running state changes from the a state to the b state and passes the downshift line as shown in FIG. 6, the downshift control from the high speed stage Hi to the low speed stage Lo, so-called kick, is performed. Down control is started. At this time, the shift control means 62 of the present embodiment shuts off the power transmission path of the automatic transmission 22 and the input shaft 64 (see FIG. 1) of the automatic transmission 22 connected to the second sun gear S2. Rotation synchronization control is performed in which the rotation speed Nin (hereinafter, input shaft rotation speed Nin) is synchronized with the rotation speed after the shift by controlling the second electric motor MG2.

  The rotation synchronization control by the second electric motor MG2 will be described. In the rotation synchronization control by the second electric motor MG2, the disengagement side frictional engagement device (the first brake B1 at the time of downshift) is suddenly lowered and released during the shift period, so that the transmission torque capacity of the automatic transmission 22 is increased. The target synchronization in which the input shaft rotational speed Nin of the automatic transmission 22 is set after the automatic transmission 22 is shifted in a state where the automatic transmission 22 is in a neutral state (power transmission cut-off state). The rotation speed Nmg2 of the second electric motor MG2 is synchronously controlled so as to be the rotation speed Np. Specifically, the deviation δ between the input shaft rotation speed Nin (second motor rotation speed Nmg2) and the target synchronous rotation speed Np is sequentially calculated, and the output torque Tmg2 of the second motor MG2 is calculated based on the calculated deviation δ. Is feedback controlled. Accordingly, the input shaft rotation speed Nin (second motor rotation speed Nmg2) changes so as to follow the target synchronous rotation speed Np. The target synchronous rotational speed Np is calculated by the product of the gear ratio of the automatic transmission 22 after the shift and the rotational speed Nout of the output shaft 14. When the rotation synchronization control is completed, the engagement hydraulic pressure of the engagement side frictional engagement device (corresponding to the second brake B2 at the time of downshifting) engaged after the shift of the automatic transmission 22 is suddenly raised and the engagement is engaged. When combined, the shifting is completed.

  By the way, when the shift determination of the automatic transmission 22 is made during the engine start process (engine start control) by the engine start control means 62, the engine start process of the engine 24 and the shift process of the automatic transmission 22 (shift control). Are simultaneously performed, the power transmission path between the second electric motor MG2 and the planetary gear device 26 is interrupted during the shift transition period, so that the reaction torque of the second electric motor MG2 is not transmitted to the planetary gear device 26. It becomes possible. Therefore, the engine start process cannot be performed, so that the execution of the shift control means 66 is restricted while the engine start control means 62 is being executed. Then, when the engine starting process of the engine 24 is completed, the shift control means 66 is implemented.

  As described above, when the shift determination of the automatic transmission 22 is made during the engine start process, the shift process (shift control) is performed after the engine start process ends, but the shift time of the automatic transmission 22 becomes longer. There is a problem that drivability deteriorates. Specifically, in the shift by the shift control means 66, the hydraulic pressure of the friction engagement device (brake B1 in the case of downshift) released at the time of shift is discharged all at once, but until the engine start control ends. During this period, the pressure is not discharged and the hydraulic pressure is maintained. When the engine start process is completed, the hydraulic pressure of the friction engagement device is discharged. However, it takes time in proportion to the hydraulic pressure to be completely discharged. Therefore, the shift time of the automatic transmission 22 becomes longer, and drivability such as slack at the time of acceleration decreases.

  On the other hand, in this embodiment, when the shift determination of the automatic transmission 22 is made during the engine start process, the hydraulic pressure of the frictional engagement element that is released when the automatic transmission 22 is shifted is changed to the first. By controlling the hydraulic pressure corresponding to the output torque Tmg2 of the two-motor MG2, the shift time is shortened and the drivability is improved. Hereinafter, the control will be described.

  The release side hydraulic pressure control means 68 controls the hydraulic pressure of the frictional engagement element on the side released at the time of shifting during the execution of the engine start control means 62. In the following description, the shift from the state a to the state b shown in FIG. 6, that is, the high speed Hi (first brake B1 engaged, the second brake B2 released) to the low speed Lo (first brake B1 released, first The downshift to 2 brake B2 engagement) will be described as an example.

  During the execution of the engine start control means 62, the vehicle traveling state moves from the a state to the b state shown in FIG. 6, so that the automatic transmission 22 is moved from the high speed stage Hi to the low speed by the shift control means 66 (shift determination means). When the downshift to the stage Lo is determined, the engine start control means 62 restricts (prohibits) the speed change process by the speed change control means 66, and the friction engagement that is released to the disengagement hydraulic control means 68 at the time of the speed change. Outputs a command to control the hydraulic pressure of the element. In response to the command, the release side hydraulic control means 68 controls the hydraulic pressure of the friction engagement element that is released at the time of shifting to a hydraulic pressure corresponding to the output torque Tmg2 of the second electric motor MG2. In the downshift of this embodiment, since the friction engagement element to be released is the first brake B1, the release side hydraulic control means 68 controls the hydraulic pressure of the first brake B1 as a control target. Accordingly, the first brake B1 of the present embodiment corresponds to the open side frictional engagement device that is released during the shift of the present invention, and the hydraulic pressure PB1 of the brake B1 corresponds to the open side hydraulic pressure of the present invention. .

  The disengagement hydraulic pressure control means 68 detects the output torque Tmg2 of the second electric motor MG2, and controls the hydraulic pressure PB1 of the first brake B1 according to the output torque Tmg2. Here, the output torque Tmg2 of the second electric motor MG2 is sequentially detected by the motor torque detecting means 70. The motor torque detection means 70 sequentially detects the output torque Tmg2 of the second electric motor MG2 based on, for example, the electric power (supply current) supplied to the second electric motor MG2 controlled by the inverter 40.

The release side hydraulic control means 68 sequentially sets the target hydraulic pressure PB1 ^* of the first brake B1 based on the output torque Tmg2 of the second electric motor MG2 detected by the motor torque detection means 70. Note that the target hydraulic pressure PB1 ^* for the output torque Tmg2 is obtained in advance by experiment or calculation, and is stored, for example, in a relation map. Specifically, the target hydraulic pressure PB1 ^* is the hydraulic pressure at which the output torque Tmg2 of the second electric motor MG2 can be transmitted to the output shaft 14 (planetary gear device 26) via the automatic transmission 22, that is, the first brake B1 is slipped. The hydraulic pressure is such that the torque capacity is such that the output torque Tmg2 can be transmitted without being set, and the hydraulic pressure is set to a minimum required value in the range or a hydraulic pressure substantially equivalent to that. For example, in this embodiment, if the hydraulic pressure PB1 at the time of complete engagement is the original pressure (line pressure PL), the value is lower than the original pressure. The release side hydraulic pressure control means 68 controls the hydraulic pressure control circuit 50 through the shift control means 66 so that the hydraulic pressure PB1 becomes the set target hydraulic pressure PB1 ^* , thereby sequentially controlling the hydraulic pressure PB1.

  When the hydraulic pressure PB1 of the first brake B1 is controlled as described above, the engine start control is performed with the hydraulic pressure PB1 being lower than normal. The normal state corresponds to a state where the first brake B1 is completely engaged. Even when engine start control is performed in this state, the hydraulic pressure PB1 is controlled so that the output torque Tmg2 of the second electric motor MG2 is transmitted to the output shaft 14 (planetary gear unit 26) via the automatic transmission 22. Therefore, the engine speed Ne is increased without causing a shock during engine start control. When the engine start process is completed, the shift process (shift control) of the automatic transmission 22 is started and the exhaust pressure of the hydraulic pressure PB1 of the first brake B1 is started. Is reduced, the time required for exhaust pressure is shorter than usual. Therefore, the shift time is shortened and drivability is improved.

  FIG. 7 shows a control operation that improves drivability by shortening the shift time when the shift of the automatic transmission 22 is judged during the main part of the control operation of the electronic control unit 28, that is, during the engine 24 starting process. This flowchart is repeatedly executed with an extremely short cycle time of about several milliseconds to several tens of milliseconds, for example. FIG. 8 is a time chart for explaining the operating state by the electronic control unit 28 when the shift of the automatic transmission 22 is determined during the start control of the engine 24.

In FIG. 7, at step SA1 (hereinafter, step is omitted) corresponding to the shift control means 66 (shift determination means), whether or not the shift of the automatic transmission 22 is determined based on, for example, the shift diagram shown in FIG. Is determined. If SA1 is negative, this control is terminated. If SA1 is affirmed, it is determined in SA2 corresponding to the engine start control means 62 whether or not an engine start process (engine start control) is being executed when determining the shift of SA1. If SA2 is negative, the conventional shift control of the automatic transmission 22 is executed at SA4 corresponding to the shift control means 66. Specifically, since the engine starting process is not performed, the exhaust pressure of the hydraulic pressure PB1 of the first brake B1 is started, and when the hydraulic pressure PB1 is completely exhausted, the rotation synchronization control by the second electric motor MG2 is performed. . On the other hand, if SA2 is affirmed, in SA3 corresponding to the release side hydraulic control means 68, the hydraulic pressure PB1 of the first brake B1 corresponding to the release side hydraulic pressure during the engine starting process corresponds to the output torque Tmg2 of the second electric motor MG2. The target hydraulic pressure PB1 ^* is controlled. Note that the target hydraulic pressure PB1 ^* is lower than the hydraulic pressure when the first brake B1 is fully engaged, and when the engine start process is completed, the exhaust pressure of the hydraulic pressure PB1 is started. Since the hydraulic pressure PB1 of the brake B1 is controlled to be lower than the target hydraulic pressure PB1 ^* as compared with the conventional one, the shift time is shortened.

Referring to FIG. 8, the engine start control by the engine start control means 62 is started at time t1 as the accelerator pedal is depressed (accelerator opening increase). As a result, the planetary gear unit 26 is controlled as shown in FIG. 5, and the engine rotation speed Ne is increased as the rotation speed of the first electric motor MG1 is increased. At this time, the output torque Tmg1 of the first electric motor MG1 increases in order to increase the rotation speed of the first electric motor MG1. Further, a reaction force torque necessary for maintaining the rotational speed of the output shaft 14 (ring gear R0) of the planetary gear device 26 is output from the second electric motor MG2. Accordingly, the output torque Tmg2 of the second electric motor MG2 increases in the same manner. Next, at time t2, when the downshift determination from the high speed stage Hi to the low speed stage Lo is made, the shift process (shift control) of the automatic transmission 22 is restricted (prohibited) to prioritize the engine start control. The Accordingly, the engine start process is continuously performed in the state where the shift process is limited from time t2 to time t3. At this time, as the open side hydraulic pressure control means 68 is implemented, as indicated by a solid line (hydraulic pressure command value), the hydraulic pressure PB1 of the first brake B1 is lower than usual based on the output torque Tmg2 of the second electric motor MG2. The target hydraulic pressure PB1 ^* is controlled. Conventionally, as indicated by the alternate long and short dash line, the hydraulic pressure PB1 of the first brake B1 is maintained in a fully engaged state. Since the hydraulic pressure indicated by the solid line is a hydraulic pressure command value, the actual hydraulic pressure is delayed by a predetermined time as indicated by the broken line with respect to the hydraulic pressure command value.

When the engine rotational speed Ne is increased to the ignitable rotational speed Nig at time t3, the engine start process is terminated as the autonomous operation of the engine 24 is started. Therefore, the torque control of the output torque Tmg1 of the first electric motor MG1 and the output torque Tmg2 of the second electric motor MG2 is completed. At the same time, the shift process (shift control) of the automatic transmission 22 that is restricted is started. Thus, at time t3, the hydraulic pressure PB1 of the first brake B1, which is the release side hydraulic pressure, is decreased as indicated by the solid line. In practice, a waiting time td1 until the hydraulic pressure PB1 of the first brake B1 is completely removed occurs as the hydraulic pressure changes and a delay occurs as shown by the broken line in response to the hydraulic response delay. Therefore, after the waiting time td1 has elapsed, at the time t4, the rotation synchronization control by the second electric motor MG2 is started. Note that the target rotation speed during the rotation synchronization control is calculated based on the gear ratio of the low speed stage Lo of the automatic transmission 22 and the output shaft rotation speed Nout corresponding to the vehicle speed V. Then, for example, feedback control based on a deviation between the current rotational speed Nmg2 of the second electric motor MG2 and the target rotational speed Nmg2 ^* is executed. At time t5, when the rotation speed Nmg2 of the second electric motor MG2 is synchronized with the target rotation speed Nmg2 ^* , the second brake corresponding to the engagement-side frictional engagement device as shown by a two-dot chain line. The engagement hydraulic pressure PB2 of B2 is increased to the line pressure PL, for example, and the shift is completed.

  Here, conventionally, as indicated by the alternate long and short dash line, when the engine start control is completed at the time point t3, the hydraulic pressure PB1 of the first brake B1 is discharged, but from the state where the first brake B1 is completely engaged. Therefore, the waiting time until the first brake B1 is completely exhausted is td2, and the waiting time is longer than in this embodiment. On the other hand, in this embodiment, the waiting time is shorter than in the prior art (td1 <td2), so the shift time is shortened and the drivability is improved.

  As described above, according to the present embodiment, when the shift determination of the automatic transmission 22 is made during the engine start process, the hydraulic pressure PB1 of the first brake B1 that is released during the shift process of the automatic transmission 22 is increased. The hydraulic pressure is controlled to correspond to the output torque Tmg2 of the second electric motor MG2. In this way, the reaction torque generated by the second electric motor MG2 required at the time of starting the engine is transmitted to the planetary gear unit 26 via the automatic transmission 22, so that the engine 24 is preferably started. . When the engine 24 start-up process is completed, control is performed to discharge the hydraulic pressure PB1. Since the hydraulic pressure PB1 is the hydraulic pressure corresponding to the output torque Tmg2 of the second electric motor MG2, the normal hydraulic pressure is set. The time during which the hydraulic pressure of the hydraulic pressure PB1 is completely discharged is shorter than usual. Therefore, the shift time is shortened and drivability is improved.

  Further, according to the present embodiment, the planetary gear device 26 is configured by a single pinion type planetary gear device, the sun gear S0 is connected to the first electric motor MG1, and the carrier CA0 is connected to the engine 24 so as to be able to transmit power, Since the ring gear R0 is connected to the output shaft 14, the engine 24 connected to the carrier CA0 rotates by rotating the first electric motor MG1 and transmitting the reaction torque of the second electric motor MG2 to the ring gear R0. Driven. Therefore, the rotation of the engine can be increased up to the ignition speed so that the engine 24 can be started.

Further, according to the present embodiment, when the automatic transmission 22 is downshifted, the hydraulic pressure PB1 is rapidly decreased, and the rotation speed Nmg2 of the second electric motor MG2 is synchronized with the target rotation speed Nmg2 ^* set after the shift. Since the rotation synchronization control is performed, if the time until the hydraulic pressure PB1 is completely released and the first brake B1 is released is shortened, the shift time is shortened. Therefore, since the shift is started from a state in which the hydraulic pressure PB1 is lower than normal according to the present invention, the shift time becomes shorter as the time until the hydraulic pressure PB1 is completely removed becomes shorter.

  Further, according to the above-described embodiment, the hydraulic pressure corresponding to the output torque Tmg2 of the second electric motor MG2 is the hydraulic pressure that ensures the torque capacity that allows the output torque Tmg2 of the second electric motor MG2 to be transmitted to the planetary gear device 26. And is set based on a relationship map of hydraulic pressure with respect to output torque obtained in advance by experiments and calculations. In this way, the hydraulic pressure PB1 is set according to the output torque Tmg2 of the second electric motor MG2, and the output torque Tmg2 of the second electric motor MG2 is transmitted to the planetary gear unit 26 via the automatic transmission 22.

  Next, another embodiment of the present invention will be described. In the following description, parts common to those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 9 is a diagram showing a shortening of the shift time when a shift of the automatic transmission 22 is determined during the main control operation of the electronic control unit 28, that is, the start control of the engine 24 in another embodiment of the present invention. 10 is another flowchart illustrating a control operation for improving drivability. FIG. 10 is a time chart for explaining the operation state by the electronic control unit 28 when the shift of the automatic transmission 22 is determined during the start control of the engine 24, and corresponds to the flowchart of FIG. is there.

  FIG. 9 is the same as FIG. 7 except that step SA3 in the flowchart of FIG. 7 described above is changed to SB3, so step SB3 will be described. When SA2 is affirmed, that is, when the shift determination of the automatic transmission 22 is made during the engine starting process, the friction on the side to be released in the shift of the automatic transmission 22 is performed in SB3 corresponding to the release-side hydraulic control means 68. The hydraulic pressure PB1 of the first brake B1, which is an engaging device, is controlled to a hydraulic pressure corresponding to the maximum torque Tmax required for starting the engine 24 described later.

In the present embodiment, the release side hydraulic control means 68 uses the hydraulic pressure PB1 of the first brake B1 which is the friction engagement device on the release side as the maximum torque Tmax of the second electric motor MG2 required for starting the engine 24. To a preset target hydraulic pressure PB1 ^* corresponding to. The target hydraulic pressure PB1 ^* is set to a necessary and sufficient value so that the first brake B1 does not slide even when the maximum torque Tmax of the second electric motor MG2 is output. The maximum torque Tmax is the maximum torque Tmax of the second electric motor MG2 required at the time of starting the engine in consideration of the vehicle running state such as the vehicle speed V and the engine oil temperature, and is obtained experimentally in advance. The opening side hydraulic control means 68 outputs a hydraulic control command to the hydraulic control circuit 50 so that the hydraulic pressure PB1 becomes a target hydraulic pressure PB1 ^* corresponding to the maximum torque Tmax. Note that the maximum torque Tmax of the second electric motor MG2 is the maximum torque required at the time of starting the engine, and is different from the maximum torque determined in terms of the rating of the second electric motor MG2.

As described above, in step SB3, the hydraulic pressure PB1 of the first brake B1 is controlled to the target hydraulic pressure PB1 ^* corresponding to the maximum torque Tmax required for starting the engine 24. Therefore, the torque that can be transmitted by the automatic transmission 22 during the engine start control is reliably prevented from being lower than the output torque Tmg2 of the second electric motor MG2, and a shock or the like during the engine start control is prevented. Specifically, in the above-described embodiment, the hydraulic pressure PB1 of the first brake B1 is set according to the output torque Tmg2 of the second electric motor MG2, but the hydraulic pressure PB1 varies according to the variation of the output torque Tmg2. Become. Here, since the actual hydraulic pressure (actual hydraulic pressure) has a response delay with respect to the hydraulic pressure command value, when the difference between the actual hydraulic pressure and the hydraulic pressure command value increases, the output torque Tmg2 can be transmitted to the automatic transmission 22. There is a possibility that the rotational speed Nmg2 of the second electric motor MG2 fluctuates unintentionally and a shock or the like occurs. On the other hand, when the hydraulic pressure PB1 is controlled to the target hydraulic pressure PB1 ^* corresponding to the maximum torque Tmax, the torque that can be transmitted by the automatic transmission 22 is always larger than the output torque Tmg2, so that the occurrence of a shock is surely prevented. Is done.

When controlled as described above, as shown in FIG. 10, the output torque Tmg2 of the second electric motor MG2 is set to the maximum torque Tmax required when starting the engine in consideration of the running state of the vehicle. As shown, the hydraulic pressure PB1 is controlled to the target hydraulic pressure PB1 ^* corresponding to the maximum torque Tmax. When the engine start process ends at time t3, a waiting time td3 occurs until the hydraulic pressure PB1 of the first brake B1 is completely discharged. The waiting time td3 is longer than the waiting time td1 of the above-described embodiment, but is shorter than the conventional waiting time td2. Therefore, the shift time is shortened compared to the conventional case, and the shock that occurs during engine start control is reliably prevented. Then, after the waiting time td3 has elapsed, at the time t4 ′, the rotation synchronization control by the second electric motor MG2 is started. Further, when the rotation synchronization control of the second electric motor MG2 is finished at the time point t5 ′, the engagement hydraulic pressure PB2 of the second brake B2 corresponding to the engagement-side friction engagement device is, for example, a line as shown by a two-dot chain line. The pressure is increased to the pressure PL and the shift is completed.

As described above, according to the present embodiment, when the shift determination of the automatic transmission 22 is made during the engine start process, the hydraulic pressure PB1 of the first brake B1 that is released when the automatic transmission 22 is shifted is changed to the engine. The target hydraulic pressure PB1 ^* corresponding to the maximum torque Tmax of the second electric motor MG2 required for starting 24 is controlled. In this way, the reaction torque generated by the second electric motor MG2 required at the time of starting the engine is transmitted to the planetary gear unit 26 via the automatic transmission 22, so that the engine 24 is preferably started. . When the starting process of the engine 24 is completed, control for exhausting the hydraulic pressure PB1 is performed. However, since the hydraulic pressure PB1 is a hydraulic pressure corresponding to the maximum torque Tmax required for starting the engine 24, the normal pressure is reduced. The pressure is lower than the hydraulic pressure, and the time for completely discharging the hydraulic PB1 hydraulic pressure is shorter than usual. Therefore, the shift time is shortened and drivability is improved. Further, since the hydraulic oil pressure PB1 is an oil pressure corresponding to the maximum torque Tmax required for starting the engine 24, it is ensured that the torque Tmg2 of the second electric motor MG2 exceeds the torque that can be transmitted by the automatic transmission 22. Thus, it is possible to reliably prevent a shock from occurring due to, for example, the rotation of the second electric motor MG2 changing to an unintended rotation speed.

  Further, according to the present embodiment, the hydraulic pressure corresponding to the maximum torque Tmax required for starting the engine 247 is the maximum torque Tmax of the second electric motor MG2 required for starting the engine which changes according to the traveling state of the vehicle. Is a hydraulic pressure that can be transmitted and is obtained and stored in advance by experiments and calculations. In this way, since the output torque Tmg2 of the second electric motor MG2 does not exceed the torque capacity allowed by the first brake B1, the rotational speed Nmg2 of the second electric motor MG2 changes to an unintended rotational speed. The occurrence of shock is reliably prevented.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, the hybrid vehicle power transmission device 10 of the above-described embodiment is the automatic transmission 22 capable of two-speed shifting. However, the shift speed of the automatic transmission 22 is not limited to the two-speed shifting, and is three or more. The present invention can be applied even to an automatic transmission 22 that can change the speed.

  In the above-described embodiment, the present invention is applied at the time of kick-down shift. However, the present invention is not necessarily limited to kick-down shift, and the present invention may be applied at the time of up-shift. In short, the present invention can be applied to any shift process (shift control) in which rotation synchronization control is performed by an electric motor during a shift.

  In the above-described embodiment, the release side hydraulic control means 68 outputs a hydraulic pressure command to the hydraulic control circuit 50 via the shift control means 66, but directly controls the hydraulic pressure without passing through the shift control means 66. A hydraulic pressure command may be output to the circuit 50.

  In the above-described embodiment, steps SA1 and SA2 shown in FIGS. 7 and 9 may be reversed.

  In the above-described embodiment, the hydraulic pressure when the first brake B1 and the second brake B2 are fully engaged is the original pressure (line pressure PL), but it is not always necessary to set the line pressure PL. The hydraulic pressure may be lower than the line pressure PL.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

10: Power transmission device for hybrid vehicle 14: Wheel side output shaft (output shaft)
22: Automatic transmission (transmission)
24: Engine 26: Planetary gear unit (differential mechanism)
28: Electronic control unit MG1: First motor (differential motor)
MG2: Second electric motor (electric motor)
B1: First brake (release side frictional engagement device)
S0: Sun gear CA0: Carrier R0: Ring gear PB1: Hydraulic pressure of first brake (opening side hydraulic pressure)
Tmg2: Output torque of the second motor (output torque of the motor)
Tmax: Maximum torque (maximum torque required to start the engine)

Claims (4)

A differential mechanism that is connected to the engine so that power can be transmitted and the differential state is electrically controlled; and an electric motor that is connected to an output shaft of the differential mechanism via a transmission so that power can be transmitted. When starting the engine, a control device for a hybrid vehicle power transmission device in which an engine starting process is performed to raise the rotational speed of the engine to a rotational speed at which the engine can be ignited in a state where reaction torque is generated by the electric motor. There,
When the shift determination of the transmission is made during the engine start process, the release side hydraulic pressure of the release side frictional engagement device that is released during the shift of the transmission is controlled to a hydraulic pressure corresponding to the output torque of the electric motor. A control apparatus for a power transmission device for a hybrid vehicle. A differential mechanism that is connected to the engine so that power can be transmitted and the differential state is electrically controlled; and an electric motor that is connected to an output shaft of the differential mechanism via a transmission so that power can be transmitted. When starting the engine, a control device for a hybrid vehicle power transmission device in which an engine starting process is performed to raise the rotational speed of the engine to a rotational speed at which the engine can be ignited in a state where reaction torque is generated by the electric motor. There,
When the shift determination of the transmission is made during the engine start process, the open side hydraulic pressure of the open side frictional engagement device that is released during the shift of the transmission is required for starting the engine. A control device for a power transmission device for a hybrid vehicle, wherein the control device is controlled to a hydraulic pressure corresponding to the maximum torque. The differential mechanism is composed of a single pinion type planetary gear device,
3. The hybrid vehicle power transmission device according to claim 1, wherein a sun gear is coupled to the differential motor, a carrier is coupled to the engine so as to transmit power, and a ring gear is coupled to the output shaft. Control device.   At the time of shifting the transmission, rotation synchronization control is performed to synchronize the rotation speed of the electric motor with a target rotation speed set after shifting with the open side frictional engagement device opened. The control device for a power transmission device for a hybrid vehicle according to claim 3, characterized in that:

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