JP6065693B2 - Control device for hybrid vehicle - Google Patents

Description

  The present invention relates to a control device for a hybrid vehicle, and more particularly to control during engine braking.

  A differential mechanism including a first rotating element coupled to the electric motor, a second rotating element coupled to the engine, and a third rotating element coupled to the drive wheel, and the power between the engine and the electric motor A hybrid vehicle including a damper device that is inserted on a transmission path is well known. The vehicle described in Patent Document 1 is an example. In Patent Document 1, a sun gear of a planetary gear device that functions as a differential mechanism is connected to an electric motor, a carrier is connected to an engine via a damper device, and a ring gear is connected to drive wheels so that power can be transmitted. A hybrid vehicle is disclosed. Further, in Patent Document 1, when the engine rotational speed is reduced, the engine rotational speed is reduced by performing a fuel cut of the engine and applying a torque opposite to the rotational direction of the engine from the electric motor toward the engine. A technique for quickly pulling down is disclosed.

Japanese Patent Laid-Open No. 10-306739

  By the way, in the hybrid vehicle described in Patent Document 1, when the engine rotation speed is reduced by the electric motor, it may be difficult to quickly decrease the engine rotation speed depending on the traveling state. For example, in the vehicle described in Patent Document 1, when the engine rotation speed of the engine connected to the carrier and the rotation speed of the drive wheel connected to the ring gear increase, the planetary gear when the engine rotation speed is reduced by the electric motor. The rotation speed of the pinion gear of the device increases. Therefore, an upper limit is set on the rotational speed of the pinion gear for the purpose of ensuring the durability of the pinion gear. In connection with the limitation of the rotation speed of the pinion gear, it is difficult to quickly reduce the engine rotation speed. For example, when the charge capacity of the power storage device exceeds an allowable value, the torque of the electric motor is limited, so that it is difficult to quickly reduce the engine rotation speed of the electric motor. In such a case, since the time during which the engine rotation speed stays in the rotation speed region where the NV characteristics deteriorate becomes longer, there is a possibility that the NV characteristics deteriorate.

  The present invention has been made in the background of the above circumstances, and its object is to connect a first rotating element connected to an electric motor, a second rotating element connected to an engine, and a drive wheel. In a hybrid vehicle comprising a differential mechanism including a third rotating element and a damper device interposed on a power transmission path between the engine and the electric motor, the engine rotational speed is increased. It is an object of the present invention to provide a control device capable of preventing the deterioration of NV characteristics when reducing.

To achieve the above object, the gist of the first invention is that: (a) a first rotating element connected to an electric motor; a second rotating element connected to an engine; and a third rotating element connected to a drive wheel. A differential mechanism including a rotating element; and a damper device interposed on a power transmission path between the engine and the electric motor, and the engine rotational speed of the engine can be controlled by the electric motor. (B) the engine includes a variable valve mechanism capable of changing at least one of a valve timing of the engine and a valve lift amount of the engine, and (c) an engine brake. If the controlling the engine rotational speed to a lower rotational speed than the resonance rotational speed range during travel, at least one of the valve timing and the valve lift And your, by reducing the pressure within the cylinder of the engine, after the resonance rotation speed region changed to lower the rotational speed side, maintaining the engine rotational speed to high rotational speed than the resonance rotational speed region, The engine speed is reduced.

In this way, when the engine speed is controlled to be lower than the resonance speed range during engine braking, the engine speed is maintained at a speed higher than the resonance speed range, thereby resonating the engine. Avoid staying in the rotational speed range. Further, since the vehicle speed decreases while maintaining the engine rotation speed at a higher rotation speed than the resonance rotation speed region, the rotation speed of each rotation element of the differential mechanism also decreases. When the rotational speed of the rotating element of the differential mechanism decreases until the engine rotational speed can be quickly decreased, the engine rotational speed can be quickly decreased by the electric motor, and the deterioration of the NV characteristics can be avoided. For example, when the charge capacity of the power storage device exceeds an allowable value, discharge by the electric motor is promoted by maintaining the engine rotational speed at a high rotational speed by the electric motor. When the charging capacity becomes a normal value, the torque limit of the electric motor is also eliminated, and the engine rotational speed can be quickly reduced by the electric motor, and the deterioration of the NV characteristic can be avoided. Further, by reducing the pressure in the engine cylinder in the resonance rotational speed region, the rotational resistance of the engine is reduced, so that the resonant rotational speed region becomes narrow. Therefore, the engine rotation speed maintained by the electric motor is also reduced and the engine braking force is reduced. Therefore, the deterioration of fuel consumption is suppressed by increasing the regeneration amount of the electric motor by the reduced engine braking force.

  Preferably, the differential mechanism is constituted by a planetary gear device, and the rotation of the pinion gear of the planetary gear device is performed when the engine rotation speed is reduced to a rotation speed lower than the resonance rotation speed region. The higher the speed, the longer it takes to maintain the rotational speed higher than the resonance rotational area as compared with the case where the speed is low. By doing so, the higher the rotational speed of the pinion gear, the longer the time for maintaining the rotational speed higher than the resonance rotational speed region as compared with the case where the rotational speed is lower, so the rotational speed of the pinion gear decreases as the vehicle speed decreases. Therefore, even when the rotation speed of the pinion gear is high, since the reduction of the engine rotation speed by the electric motor is started when the rotation speed of the pinion gear decreases, the residence time in the resonance rotation speed region is shortened, and the NV characteristic Deterioration is avoided. On the other hand, when the rotational speed of the pinion gear is low, the time for maintaining the engine rotational speed at a rotational speed higher than the resonance rotational speed region is shortened, so that the engine rotational speed is rapidly decreased. Thus, the time for maintaining the engine speed at a higher speed than the resonance speed range is optimally adjusted according to the speed of the pinion gear, and the engine speed is rapidly reduced while avoiding the deterioration of NV characteristics. can do.

  Preferably, when charging of the battery that exchanges electric power with the electric motor is restricted, the engine rotation speed is maintained at a higher rotation speed than the resonance rotation area. By doing so, it is possible to avoid the deterioration of the NV characteristics by maintaining the engine rotation speed at a higher rotation speed than the resonance rotation speed region. Further, by maintaining the engine rotation speed at a higher rotation speed than the resonance rotation speed region, it is possible to promote battery discharge and return the battery charge amount to a normal value.

It is a schematic block diagram explaining the vehicle drive device of the hybrid vehicle to which this invention was applied. It is a figure which shows the twist characteristic of the damper apparatus of FIG. It is a time chart which shows the operation state during motoring travel. It is a time chart which shows the operation state in other modes of motoring traveling. 2 is a flowchart for explaining a main part of a control operation of the electronic control device of FIG. 1, that is, a control operation that can prevent deterioration of NV characteristics during motoring traveling. It is a flowchart explaining the principal part of the control action of the electronic control apparatus corresponding to the other Example of this invention, ie, the control action which can prevent the deterioration of the NV characteristic during motoring driving | running | working. It is a flowchart explaining the principal part of the control action of the electronic control apparatus corresponding to the further another Example of this invention, ie, the control action which can prevent the deterioration of the NV characteristic during motoring driving | running | working.

  Here, preferably, in this specification, the motoring control is to control the engine rotational speed to a predetermined rotational speed by controlling an electric motor in order to generate a predetermined engine braking force during engine braking. It is.

  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 vehicle drive device 10 of a hybrid vehicle 8 (vehicle 8) to which the present invention is applied. The vehicle drive device 10 includes an engine 24, a power transmission device 12, and a damper device 38, which will be described later, provided between the engine 24 and the power transmission device 12. In FIG. 1, in the vehicle drive device 10, in the vehicle 8, the torque of the engine 24 that is a main drive source is transmitted to the wheel-side output shaft 14 via a damper device 38 and a planetary gear device 26 which will be described later. Torque is transmitted from the side output shaft 14 to the pair of left and right drive wheels 18 via the differential gear device 16. Further, the vehicle drive device 10 is provided with 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 two electric motor MG2 is connected to the wheel side output shaft via the automatic transmission 22. Accordingly, the output torque transmitted from the second electric motor MG2 to the wheel side output shaft is the speed ratio γs set by the automatic transmission 22 (= the rotational speed Nmg2 of the second electric motor MG2 / the rotational speed Nout of the wheel side output shaft). It is designed to increase or decrease depending on.

  The automatic transmission 22 interposed in the power transmission path between the second electric motor MG2 and the drive wheels 18 is configured to be able to establish a plurality of stages with a gear ratio γs larger than “1”. Since the torque can be increased and transmitted to the wheel-side output shaft during powering to output torque from the second electric motor MG2, the second electric motor MG2 is configured to have a lower capacity or a smaller size. Thereby, for example, when the rotational speed Nout of the wheel side output shaft increases with the high vehicle speed, the second gear ratio γs is reduced to maintain the second motor MG2 in a good state. When the rotational speed Nmg2 of the motor MG2 (hereinafter referred to as the second motor rotational speed) Nmg2 is decreased, or when the rotational speed Nout of the wheel side output shaft is decreased, the gear ratio γs is increased to increase the second motor rotational speed Nmg2. Increase.

  The power transmission device 12 includes a first electric motor MG1 and a second electric motor MG2, and transmits the torque of the engine 24 to the drive wheels 18. 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 is an electronic control device 100 (E-ECU) for engine control (not shown) mainly composed of a microcomputer. Thus, the operation state such as the throttle valve opening, the intake air amount, the fuel supply amount, and the ignition timing is electrically controlled. Further, the engine 24 includes a variable valve mechanism 25, and the valve timing and valve lift amount of the engine 24 can be adjusted as appropriate.

  The electronic control device 100 (control device) includes a signal indicating an accelerator opening Acc that is an operation amount of the accelerator pedal from the accelerator operation amount sensor AS, a signal indicating presence / absence Bon of the brake pedal from the brake sensor BS, and a crank angle. A signal representing the engine rotational speed Ne corresponding to the crank angle of the crankshaft 36 from the sensor 43, a signal representing the first motor rotational speed Nmg1 of the first motor MG1 from the first resolver 44, and a second from the second resolver 46. A signal representing the second motor rotational speed Nmg2 of the motor MG2, a signal representing the rotational speed Nout of the wheel side output shaft 14 corresponding to the vehicle speed V from the output shaft rotational speed sensor 48, and an engine water temperature Tw from the engine water temperature sensor 49. A signal, a signal representing the charge capacity SOC of the power storage device 32 (battery) from the battery sensor 50, and the like are supplied.

  The first electric motor MG1 (electric motor) is, for example, a synchronous motor, and is configured to selectively generate a function as a motor for generating a driving torque Tm1 and a function as a generator, and a battery via an inverter 30. Are connected to a power storage device 32 such as a capacitor. The inverter 30 is controlled by an electronic control device 100 (MG-ECU) (not shown) for controlling the motor generator, which is mainly composed of a microcomputer, so that the output torque Tm1 or the regenerative torque Tm1 of the first electric motor MG1 is adjusted or adjusted. It is set up. By controlling the first electric motor MG1, the differential state of the planetary gear unit 26 can be controlled to control the engine rotational speed Ne. The first electric motor MG1 corresponds to the electric motor of the present invention.

  The planetary gear device 26 includes three types of a sun gear S0, a ring gear R0 arranged concentrically with the sun gear S0, and a carrier CA0 that supports the sun gear S0 and the pinion gear P0 meshing with the ring gear R0 so as to rotate and revolve freely. It is a single pinion type planetary gear mechanism that is provided as a rotating element and 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 device 38 and a power transmission shaft 39. On the other hand, the first motor MG1 is connected to the sun gear S0, and the drive wheels 18 are connected to the ring gear R0 via the wheel side output shaft 14 and the differential gear device 16. 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 planetary gear device 26 corresponds to the differential mechanism of the present invention, the sun gear S0 corresponds to the first rotating element of the present invention, the carrier CA0 corresponds to the second rotating element of the present invention, and the ring gear R0 corresponds to the present invention. Corresponds to the third rotation element.

  In the planetary gear unit 26, when the reaction torque Tm1 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 (output shaft rotational speed) Nout of the wheel side output shaft 14 is constant, the rotational speed Nmg1 of the first electric motor MG1 is changed up and down to thereby increase the rotational speed of the engine 24. (Engine speed) Ne can be changed continuously (steplessly).

  The automatic transmission 22 of the present embodiment is constituted by 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 small diameter portion of the stepped pinion P1. Meshes with the pinion P2, and the pinion P2 meshes with the 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 (electric motor) is controlled via the inverter 40 by the electronic control device 100 (MG-ECU) for controlling the motor generator, thereby functioning as an electric motor or a generator, and assist output torque. Alternatively, the regenerative torque is adjusted or set. The second sun gear S2 is connected to the second electric motor MG2, and the carrier CA1 is connected to the wheel side output shaft. The first sun gear S1 and the ring gear R1 constitute a mechanism corresponding to a tuple 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 H with the ratio γsh is established and the second brake B2 is engaged instead of the first brake B1, the low speed stage L with the speed ratio γsl larger than the speed ratio γsh of the high speed stage H 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.

  The damper device 38 of this embodiment is provided on a power transmission path between the engine 24 and the first electric motor MG1, and includes a positive / negative variable hysteresis mechanism (not shown) that generates different hysteresis torques depending on whether the torsion angle is positive or negative. ing. FIG. 2 shows the torsional characteristics of the damper device 38 of the present embodiment. In FIG. 2, the horizontal axis indicates the twist angle θ (rad) of the damper device 38, and the vertical axis indicates the torque (Nm). As shown in FIG. 2, a small hysteresis torque H1 is generated in a torsion angle region where the torsion angle θ is in the positive direction (positive side), that is, a region in which torque (driving force) is transmitted from the engine side. On the other hand, a large hysteresis torque H2 is generated in a torsion angle region where the torsion angle θ is negative, that is, a region where torque is transmitted from the first motor side to the engine side. Thus, the large hysteresis generated by the negative twist of the damper device 38 twisted by the first electric motor MG1 is larger than the small hysteresis torque H1 generated by the positive twist (positive side) of the damper device 38 twisted by the engine 24. The hysteresis torque H2 is set to be larger. Since the variable hysteresis mechanism that generates different hysteresis torques depending on whether the torsion angle θ is positive or negative is a known technique, a detailed description of the structure and the like is omitted.

  In the damper device 38 configured as described above, for example, when the engine is started, the engine rotational speed Ne is increased by the first electric motor MG1, so that the damper device 38 has a negative twist angle. Accordingly, the large hysteresis torque H2 is generated, and the torsional resonance when the engine speed Ne passes through the resonance frequency region is attenuated. Further, since the small hysteresis torque H1 is generated while the engine is being driven, the humming noise and rattling noise generated in the power transmission device 12 are suppressed. Here, during engine braking (motoring), the engine speed Ne is controlled by the first electric motor MG1. It is preferable to generate a small hysteresis torque in order to suppress the humming noise and the rattling noise even during the engine braking. However, since the damper device 38 during engine braking is in a state of being twisted by the first electric motor MG1, the damper device 38 has a negative twist angle and generates a large hysteresis torque H2. Therefore, there is a problem that the booming noise and the rattling noise cannot be effectively suppressed, and the NV characteristic is deteriorated.

  On the other hand, there is a method for preventing the deterioration of the NV characteristics by causing the first electric motor MG1 to quickly pass through the engine rotation speed region in the rotation speed region where the NV characteristics are deteriorated (hereinafter referred to as the NV deterioration rotation speed region). However, for example, if the reduction of the engine rotation speed Ne by the first electric motor MG1 is started with the engine rotation speed Ne and the vehicle speed V being high, the rotation speed of the pinion gear P0 may be increased and the durability of the pinion gear may be reduced. Arise. In order to prevent this, the upper limit rotation speed Npin_max of the pinion gear P0 is preset in advance so that the durability of the pinion gear P0 does not deteriorate. When the upper limit rotation speed Npin_max is set for the pinion gear P0, it is difficult to quickly decrease the engine rotation speed Ne in the NV deterioration rotation speed region, so that a booming noise and a rattling sound are generated and the NV characteristics are deteriorated. There was a possibility. Therefore, when the electronic control unit 100 reduces the engine rotation speed Ne to a rotation speed lower than the NV deterioration rotation speed region during engine braking (motoring driving), the electronic control device 100 decreases the engine rotation speed Ne from the NV deterioration rotation speed region. After maintaining for a predetermined waiting time at a high rotational speed, the engine rotational speed Ne is decreased. Hereinafter, the control operation of the electronic control device 100 according to the present invention will be described in detail.

  Returning to FIG. 1, the electronic control unit 100 functionally includes a motoring determination unit 102, a target engine rotation determination unit 104, a valve control unit 106, and a motoring control unit 108. The motoring determination unit 102 determines whether or not the engine 24 is in a motoring state, that is, a traveling state in which the engine rotation speed Ne is controlled by the first electric motor MG1 while the engine is in a brake traveling state. The motoring determination unit 102 determines that the engine 24 is in a motoring state based on, for example, the state where the accelerator pedal is released or the vehicle speed V is released.

  When the motoring determination unit 102 determines that the engine 12 is in the motoring state, the target engine rotation determination unit 104 is executed. The target engine rotation determination unit 104 determines a target rotation speed Ne * of the engine 12 to be maintained during motoring traveling (engine braking traveling). The target engine rotation determination unit 104 calculates a first engine rotation speed Ne1 at which the pinion rotation speed Npin of the pinion gear P0 is equal to or lower than the upper limit rotation speed Npin_max, based on the vehicle speed V and the preset upper limit rotation speed Npin_max of the pinion gear P0. . The rotational speed Ns of the sun gear S0 (first motor rotational speed Nmg1), the rotational speed Nr of the ring gear R0 (rotational speed Nout of the wheel output shaft 14), the rotational speed Nca of the carrier CA0 (engine rotational speed Ne), and the planetary gears. The first engine rotational speed Ne1 can be calculated based on a known arithmetic expression for calculating the pinion rotational speed Npin of the pinion gear P0, such as the gear ratio ρ of the device 26.

  Next, the target engine rotation determination unit 104 determines whether or not the calculated first engine rotation speed Ne1 is in the NV deterioration rotation speed region (N1_L to N1_U) in which the NV characteristics that are obtained and stored in advance are deteriorated. judge. When the first engine rotational speed Ne1 is in the NV deteriorated engine rotational speed region (N1_L <Ne1 <N1_U), the NV deteriorated upper limit rotational speed N1_U is set to the target rotational speed Ne * in order to avoid the deterioration of the NV characteristics. decide. If the first engine rotational speed Ne1 is not in the NV deterioration rotational speed region, the NV characteristic does not deteriorate even if the first engine rotational speed Ne1 is maintained at that rotational speed, so the first engine rotational speed Ne1 is determined as the target rotational speed Ne *. . The NV deterioration rotational speed region corresponds to the resonance rotational speed region of the present invention.

  This NV worsening rotational speed region (N1_L to N1_U) is determined based on the structure of the vehicle drive device 10, the engine water temperature Tw, and the like. For example, the NV worsening defined by the gear stage of the automatic transmission 22, the engine water temperature Tw, and the like. It is stored as an area map. The engine 24 includes a variable valve mechanism 25 that adjusts the valve opening / closing timing and the valve lift amount by controlling the hydraulic pressure, for example, and delays the valve closing timing, for example, during motoring travel. Decompression (decompression control, decompression control) for reducing the pressure in the 24 cylinders can be performed. Since the variable valve mechanism 25 is a known technique, the description thereof is omitted. When this decompression is executed, the NV deterioration rotation speed region becomes narrower in connection with the decrease in the running resistance (engine braking force) during engine braking. Therefore, the NV deteriorated rotation speed region map when the decompression control is performed and the NV deteriorated rotation speed region map when the decompression control is not performed are separately provided. In the following, the rotational speed (N1_L to N1_U) is defined as an NV worsening rotational speed region when the decompression control is performed, and the rotational speed region (N2_L to N2_U) is an NV worsening rotational speed region when the decompression control is not performed. It is defined as Further, the pressure in the cylinder can be reduced not only by adjusting the valve timing but also by adjusting the valve lift amount. Accordingly, the decompressor may be any one that can perform at least one of the valve timing and the valve lift amount.

  The valve control unit 106 optimally adjusts at least one of the valve timing and the valve lift amount of the variable valve mechanism 25 during engine braking. The valve control unit 106 controls the valve timing and the valve lift amount based on a preset timing map of valve timing or a valve lift amount map of the valve lift amount. The timing map and the valve lift amount map are maps using, for example, the engine rotational speed Ne and the engine torque Te as parameters. When decompression is executed, the engine 24 is adjusted by adjusting the valve timing and the valve lift amount. The pressure in the cylinder is reduced, and the NV deterioration rotational speed region is narrowed.

  The motoring control unit 108 controls the first electric motor MG1 so that the engine rotation speed Ne during engine braking is equal to the target rotation speed Ne * determined by the target engine rotation determination unit 104, and the engine rotation speed Ne. Is maintained at the target rotational speed Ne * for a predetermined waiting time T. When a predetermined waiting time T elapses, the motoring control unit 108 controls the first electric motor MG1 so that the engine rotation speed Ne passes quickly through the NV deterioration rotation speed region.

  Here, the predetermined standby time T is equal to the upper limit rotational speed Npin_max of the pinion rotational speed Npin even if the engine speed Ne is lowered to the lower limit speed N1_L of the NV worsening rotational speed region by the first electric motor MG1 after the standby time has elapsed. It is set to a non-reachable time. When the motoring control unit 108 reduces the engine speed Ne to the lower limit speed N1_L, the motoring control unit 108 calculates a vehicle speed V1 at which the pinion rotational speed Npin is equal to or lower than the upper limit rotational speed Npin_max, and when the vehicle speed V becomes lower than the vehicle speed V1. The engine rotation speed Ne by the first electric motor MG1 is started. Accordingly, the higher the pinion rotational speed Npin and the vehicle speed V at the start of motoring (start of emblem), the longer the waiting time T for maintaining the engine rotational speed Ne at the target rotational speed Ne * as compared to the lower case. If the waiting time T becomes longer, the vehicle speed V after the elapse of the waiting time also decreases, so the pinion rotation speed Npin also decreases. When the engine rotation speed Ne is decreased by the first electric motor MG1, the pinion rotation The speed Npin can be made equal to or lower than the upper limit rotational speed Npin_max.

  FIG. 3 is a time chart showing an operating state during execution of motoring control. In FIG. 3, the horizontal axis indicates the elapsed time, and the vertical axis indicates the vehicle speed V (m / s), the pinion rotational speed Npin (rpm), and the engine rotational speed Ne (rpm) in order from the top. When deceleration is started at time t1, the target engine speed determination unit 104 determines the target engine speed Ne * of the engine speed Ne and performs motoring control so that the engine speed Ne becomes the target engine speed Ne *. Controlled by the unit 108. At this time, the valve control unit 106 is also executed, so that the NV deterioration rotation speed region is appropriately adjusted. In FIG. 6, the NV deterioration upper limit rotational speed N1_U is set to the target rotational speed Ne *.

  Immediately after time t1, the engine speed Ne is rapidly reduced by the first electric motor MG1 until the pinion speed Npin reaches the upper limit speed Npin_max. The engine rotation speed Ne is controlled so that the pinion rotation speed Npin is maintained at the upper limit rotation speed Npin_max. When the engine rotation speed Ne reaches the NV deterioration upper limit rotation speed N1_U that is the upper limit value of the NV deterioration rotation speed region at time t2, the engine rotation speed Ne is maintained at the NV deterioration upper limit rotation speed N1_U for the waiting time T. As a result, the engine rotational speed Ne deviates from the NV worsening rotational speed region, so that the muffled noise and rattling noise are suppressed. Further, since the vehicle speed V decreases while the engine rotation speed Ne is maintained at the NV deterioration upper limit rotation speed N1_U (from time t2 to time t3), the pinion rotation speed Npin also decreases. At time t3 when the standby time T elapses, the first motor MG1 is controlled so that the pinion rotational speed Npin is equal to or lower than the upper limit rotational speed Npin_max even if the engine rotational speed Ne passes through the NV deterioration rotational speed region quickly. Become. Further, after the time point t3, the engine speed Ne falls below the NV deterioration speed range and is temporarily held at the preset minimum motoring speed Ne_min of the engine 24, and then the time point t4. The engine 24 is stopped.

  FIG. 4 shows another aspect of the motoring control unit 108. For example, when the engine 24 is stopped, if the engine rotational speed Ne is controlled to the target rotational speed Ne * (N2_U) at the time t2, the engine rotational speed Ne is maintained at the target rotational speed Ne * as indicated by a one-dot chain line. When the vehicle speed V is such that the engine rotation speed Ne can be reduced to zero rotation, the engine 24 is stopped at time t4. By controlling in this way, the fuel consumption is reduced by maintaining the engine rotational speed Ne at a high rotational speed for a long time by the first electric motor MG1, but the gradient change of the engine rotational speed Ne is reduced. Further improve. In particular, when the NV deteriorated rotation speed region and the minimum motoring rotation speed Ne_min are close to each other, the fuel efficiency deterioration does not become remarkable, so that it is preferably executed.

  A two-dot chain line is a mode when decompression by the valve control unit 106 is executed. When decompression is not executed, the NV deterioration rotational speed region is between N2_L and N2_U. On the other hand, when decompression is performed, the NV worsening rotational speed region becomes between N1_L (= N2_L) and N1_U, and the NV worsening rotational speed region is narrowed. As a result, the target rotational speed Ne * of the engine rotational speed Ne becomes a lower rotational speed than when the decompression is not performed, and the regeneration amount of the first electric motor MG1 can be increased by the decrease in the engine braking force resulting from this. Fuel consumption is improved. In addition, since the NV deterioration rotational speed region is narrowed, the waiting time T (frequency) for maintaining the engine rotational speed Ne at the target rotational speed Ne * by the first electric motor MG is also reduced.

  FIG. 5 is a flowchart for explaining a main part of the control operation of the electronic control unit 100, that is, a control operation that can prevent the deterioration of the NV characteristic during the motoring travel. This flowchart is repeatedly executed with an extremely short cycle time of, for example, about several milliseconds to several tens of milliseconds.

  First, in step S1 (hereinafter, step is omitted) corresponding to the motoring determination unit 102, it is determined whether or not the motoring traveling (engine braking traveling) is being performed. If S1 is negative, the routine is terminated. When S1 is affirmed, in S2 corresponding to the target engine rotation determination unit 104, the first engine rotation speed Ne1 at which the pinion rotation speed Npin is equal to or lower than the upper limit rotation speed Npin_max is calculated. In S3 corresponding to the target engine rotation speed 104, it is determined whether or not the first engine rotation speed Ne1 calculated in S2 is in the NV deterioration rotation speed region (N1_L <Ne1 <N1_U).

  When S3 is negative, since the first engine speed Ne1 is not in the NV deterioration speed range (N1_L to N1_U) in S5 corresponding to the target engine speed 104 and the valve control unit 106, the first engine speed Ne1 is determined as the target rotational speed Ne *. The motoring control unit 108 controls the engine rotational speed Ne to the target rotational speed Ne * (= Ne1), and after maintaining the rotational speed Ne1 for a predetermined waiting time T, the NV deterioration rotational speed region is quickly set. Let it pass. As a result, the time during which the engine rotation speed Ne stays in the NV deterioration rotation speed region is shortened, so that the NV characteristics are improved. At the same time, the pressure in the cylinder of the engine 24 is decompressed (decompressed) by appropriately adjusting the valve timing and valve lift amount of the engine 24. Therefore, the NV deterioration rotation region is narrowed from the rotation speed region (N2_L to N2_U) to the rotation speed region (N1_L to N1_U).

  When S3 is affirmed, in S4 corresponding to the target engine speed 104 and the valve control unit 106, the first engine speed Ne1 is in the NV deteriorated rotation speed region (N1_L <Ne1 <N1_U), so the NV deteriorated upper limit rotation. The speed N1_U is determined as the target rotational speed Ne *. Then, the motoring control unit 108 controls the engine rotational speed Ne to the target engine rotational speed Ne * (N1_U) and maintains it for a predetermined waiting time T, and then promptly passes the NV worsening rotational speed region. As a result, the time during which the engine rotation speed Ne stays in the NV deterioration rotation speed region is shortened, so that the NV characteristics are improved. At the same time, the pressure in the cylinder of the engine 24 is decompressed (decompressed) by appropriately adjusting the valve timing and valve lift amount of the engine 24. Therefore, the NV deterioration rotation region is narrowed from the rotation speed region (N2_L to N2_U) to the rotation speed region (N1_L to N1_U).

  As described above, according to this embodiment, when the engine rotation speed Ne is controlled to a lower rotation speed than the NV worsening rotation speed region during motoring running (engine braking running), the engine rotation speed Ne is worsened by NV. By maintaining at a higher rotational speed than the rotational speed region, stagnation of the engine 24 in the NV worsening rotational speed region is avoided. Further, since the vehicle speed V decreases while maintaining the engine rotational speed Ne at a rotational speed higher than the NV deterioration rotational speed region, the pinion rotational speed Npin of the planetary gear unit 26 also decreases. Then, when the pinion rotation speed Npin and the vehicle speed V of the planetary gear device 26 are decreased until the engine rotation speed Ne can be rapidly decreased, the first motor MG1 quickly decreases the engine rotation speed Ne, and the NV characteristics. Can be avoided.

  In addition, according to the present embodiment, when the engine speed Ne is decreased to a lower rotational speed than the NV worsening rotational speed region, the higher the pinion rotational speed Npin of the pinion gear P0, the lower the NV worsening rotational speed region. The waiting time T maintained at a higher rotational speed is longer. In this way, the higher the pinion rotational speed Npin of the pinion gear P0, the longer the waiting time T for maintaining the rotational speed higher than the NV worsening rotational speed region as compared with the case where the pinion rotational speed Npin is lower. The pinion rotation speed Npin decreases. Accordingly, even when the pinion rotation speed Npin of the pinion gear P0 is high, the decrease in the engine rotation speed Ne by the first electric motor MG1 starts when the pinion rotation speed Npin of the pinion gear P0 decreases, so the NV deterioration rotation speed. The residence time of the region is shortened, and the deterioration of NV characteristics is avoided. On the other hand, when the pinion rotational speed Npin is low, the time for maintaining the engine rotational speed Ne at a rotational speed higher than the NV deterioration rotational speed region is also shortened, so that the engine rotational speed Ne is rapidly decreased. As described above, the waiting time T for maintaining the engine rotation speed Ne at a higher rotation speed than the NV deterioration rotation speed region is optimally adjusted according to the pinion rotation speed Npin, and the engine rotation speed is avoided while avoiding the deterioration of the NV characteristics. Ne can be quickly reduced.

  Further, according to the present embodiment, the variable valve mechanism 25 capable of changing at least one of the valve timing and the valve lift amount of the engine 24 is provided, and at least one of the valve timing and the valve lift amount of the engine 24 is provided. By performing the control, decompression is performed to reduce the pressure in the cylinder of the engine 24 in the NV deterioration rotational speed region. In this way, the decompression in which the pressure in the cylinder is reduced in the NV worsening rotational speed region is performed, so that the rotational resistance of the engine 24 is reduced and the NV worsening rotational speed region becomes narrower. Therefore, the amount of regeneration of the first electric motor MG1 can be increased by the amount that the target rotational speed Ne * decreases and the engine braking force decreases, so that deterioration in fuel consumption is also suppressed.

  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.

  In the vehicle 8 of the present embodiment, for example, in order to suppress a change in driving force due to so-called intermittent engine operation in which the engine 24 is repeatedly started and stopped during low speed operation, control for prohibiting intermittent engine operation is executed. Hereinafter, the control during the motoring traveling when the control for prohibiting the intermittent engine operation is accompanied will be described.

  The target engine rotation determination unit 104 of the present embodiment calculates the second engine rotation speed Ne2 in consideration of prohibiting intermittent operation of the engine 24. The target engine rotation determination unit 104 calculates a second engine rotation speed Ne2 that avoids starting / stopping of the engine 24 based on the rated value of the engine 24, the charge capacity SOC of the power storage device 32, and the like. Then, the target engine rotation determination unit 104 determines whether or not the calculated second engine rotation speed Ne2 is in the NV worsening rotation speed region (N1_L to N1_U). When the second engine rotational speed Ne2 is in the rotational speed region where the NV characteristics deteriorate, in order to avoid the deterioration of the NV characteristics, the target engine rotation determining unit 104 sets the NV deterioration upper limit rotational speed N1_U to the target engine rotational speed Ne *. decide. When the second engine rotational speed Ne2 is not in the rotational speed region where the NV characteristics deteriorate, the target engine rotational speed determination unit 104 determines the second engine rotational speed Ne2 as the target engine rotational speed Ne *.

  FIG. 6 is a flowchart for explaining the main part of the control operation of the electronic control device 100 corresponding to the present embodiment, that is, the control operation that can prevent the deterioration of the NV characteristic during the motoring travel.

  First, in S1 corresponding to the motoring determination unit 102, it is determined whether or not the motoring traveling is in progress. If S1 is negative, the routine is terminated. When S1 is affirmed, in S11 corresponding to the target engine rotation determination unit 104, the second engine rotation speed Ne2 that avoids intermittent engine operation is calculated. Next, in S12 corresponding to the target engine rotation determination unit 104, it is determined whether or not the second engine rotation speed Ne2 is in the NV deterioration rotation speed region (N1_L <Ne2 <N1_U).

  If S12 is negative, the second engine rotational speed Ne2 is not in the rotational speed region in which the NV characteristic deteriorates in S14 corresponding to the target engine rotational determination unit 104 and the valve control unit 106, so the second engine rotational speed Ne2 is The target rotational speed Ne * is determined. Then, the engine speed Ne is controlled to the target engine speed Ne * (= Ne2) by the motoring control unit 108, and after maintaining at the speed Ne2 for a predetermined waiting time T, the NV deteriorated speed range is quickly set. To pass through. As a result, the time during which the engine rotation speed Ne stays in the NV deterioration rotation speed region is shortened, so that the NV characteristics are improved. In parallel with this, the pressure of the engine 24 is decompressed (decompressed) by appropriately adjusting the bubble timing and valve lift amount of the engine 24. Therefore, the NV deterioration rotation region is narrowed from the rotation speed region (N2_L to N2_U) to the rotation speed region (N1_L to N1_U). In particular, if decompression is performed only in the NV worsening rotation speed region, engine torque response during sudden acceleration is also improved.

  When S12 is affirmed, in S13 corresponding to the target engine rotation determination unit 104 and the valve control unit 106, the second engine rotation speed Ne2 is in a rotation speed region in which the NV characteristics deteriorate, so the target engine rotation speed Ne * is The NV deterioration upper limit rotational speed N1_U is determined. Then, the engine speed Ne is controlled to the target engine speed Ne * (= N1_U) by the motoring control unit 108 and maintained at that speed for a predetermined waiting time T, and then the NV worsening speed range is quickly set. Let it pass. As a result, the time during which the engine rotation speed Ne stays in the NV deterioration rotation speed region is shortened, so that the NV characteristics are improved. At the same time, the pressure in the cylinder of the engine 24 is decompressed (decompressed) by appropriately adjusting the valve timing and valve lift amount of the engine 24. Therefore, the NV deterioration rotation region is narrowed from the rotation speed region (N2_L to N2_U) to the rotation speed region (N1_L to N1_U).

  In the present embodiment, when the charging capacity SOC of the power storage device 32 exceeds a preset upper limit value and the charging control (regeneration control) of the first electric motor MG1 is limited, the motoring control is performed. The control operation will be described.

  The target engine rotation determination unit 104 according to the present embodiment calculates the third engine rotation speed Ne3 that is calculated based on the battery discharge request amount, the required braking force, and the like when the charging of the power storage device 32 is restricted. The third engine rotational speed Ne3 is a rotational speed at which electric power required by controlling the rotational speed Ne3 by the first electric motor MG1 is discharged and a required braking force (engine braking force) is obtained. . When the engine rotation speed Ne increases, the power consumed by the first electric motor MG1 to maintain the rotation speed also increases, and the engine braking force also increases. Therefore, the third engine rotation speed Ne3 is higher than the NV deterioration upper limit rotation speed N2_U, so that the discharge of the power storage device 32 and a high engine braking force are ensured. The required battery discharge amount is calculated based on, for example, the difference between the current charge capacity SOC and a preset allowable charge capacity, and the required braking force is calculated based on, for example, the amount of depression of the brake pedal. The

  Then, the target engine rotation determination unit 104 determines whether or not the calculated third engine rotation speed Ne3 is lower than the NV deterioration upper limit rotation speed N2_U in the NV deterioration rotation speed region (N2_L to N2_U). When the third engine rotation speed Ne3 is lower than the NV deterioration upper limit rotation speed N2_U, the target engine rotation determination unit 104 prevents the engine 24 from operating in the rotation speed region below the NV deterioration upper limit rotation speed N2_U where the NV characteristics deteriorate. The upper limit rotational speed N2_U is determined as the target engine rotational speed Ne *. When the third engine rotation speed Ne3 is equal to or higher than the upper limit rotation speed N2_U, the target engine rotation speed determination unit 104 determines the third engine rotation speed Ne3 as the target engine rotation speed Ne *.

  Here, in the present embodiment, basically, decompression is not performed, and the NV deterioration rotational speed region (N2_L to N2_U) becomes a rotational speed (N2_L to N2_U) on the premise that decompression control is not performed. When charging of the power storage device 32 is restricted as in the present embodiment, the braking force due to regeneration (power generation) of the first electric motor MG1 cannot be obtained, so that the required engine braking force increases accordingly. On the other hand, when decompression is performed, the engine braking force obtained by reducing the rotational resistance force of the engine 24 becomes small. Therefore, when the charging of the power storage device 32 is restricted, the decompression is basically not performed, and based on the NV deterioration rotation speed region (N2_L to N2_U) on the assumption that the decompression is not performed. It is determined whether or not the 3 engine rotation speed Ne3 is in the NV deterioration rotation speed region.

  FIG. 7 is a flowchart for explaining a main part of the control operation of the electronic control device 100 corresponding to the present embodiment, that is, a control operation that can prevent deterioration of the NV characteristic during motoring traveling.

  First, in S1 corresponding to the motoring determination unit 102, it is determined whether or not the motoring traveling is in progress. If S1 is negative, the routine is terminated. When S1 is affirmed, in S21 corresponding to the target engine rotation determination unit 104, the third engine rotation speed Ne3 is calculated based on the required battery discharge amount, the required braking force, and the like. Next, in S22 corresponding to the target engine rotation determination unit 104, it is determined whether or not the third engine rotation speed Ne3 is lower than the upper limit rotation speed N2_U.

  If S22 is negative, since the third engine speed Ne3 is not in the rotational speed region where the NV characteristic deteriorates in S24 corresponding to the target engine speed determination unit 104 and the valve control unit 106, the third engine speed Ne3 is The target rotational speed Ne * is determined. Then, the motoring control unit 108 controls the engine rotational speed Ne to the target rotational speed Ne * (= Ne3) and maintains the rotational speed for a predetermined waiting time T, and then quickly passes through the NV deterioration rotational speed region. Let As a result, the time during which the engine rotation speed Ne stays in the NV deterioration rotation speed region is shortened, so that the NV characteristics are improved. At the same time, the valve timing and valve lift amount of the engine 24 are adjusted as appropriate so that decompression is not performed.

  If S22 is positive, in S23 corresponding to the target engine rotation determination unit 104 and the valve control unit 106, the third engine rotation speed Ne3 is at a rotation speed lower than the upper limit rotation speed N2_U. Therefore, the upper limit rotational speed N2_U is determined as the target rotational speed Ne *. Then, the motoring control unit 108 controls the engine rotational speed Ne to the upper limit rotational speed N2_U and maintains it at the rotational speed for a predetermined waiting time T, and then quickly passes the NV deterioration rotational speed region. At the same time, the valve timing and valve lift amount of the engine 24 are adjusted as appropriate so that decompression is not performed.

  As described above, this embodiment can provide the same effects as those of the above-described embodiment. When charging of power storage device 32 that exchanges power with first motor MG1 is restricted, engine rotation speed Ne is maintained at a rotation speed higher than the NV deterioration rotation speed region. By doing so, it is possible to avoid the deterioration of the NV characteristics by maintaining the engine rotation speed Ne at a higher rotation speed than the NV deterioration rotation speed region. Further, by maintaining the engine rotation speed Ne at a higher rotation speed than the NV deterioration rotation speed region, it is possible to promote the discharge of the power storage device 32 and return the storage capacity SOC to a normal value. Furthermore, since the engine rotation speed Ne increases, the engine braking force also increases, and a desired braking force can be ensured.

  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, each of the above-described embodiments has been described independently. However, the embodiments may be combined as appropriate within a range where no contradiction occurs.

  In the above-described embodiment, when the first engine rotational speed Ne1 is in the NV worsening rotational speed region, the target rotational speed Ne * is set to the NV worsening upper limit rotational speed N1_U, but the target rotational speed Ne * is the NV worsening upper limit rotational speed. Any rotational speed higher than the speed N1_U may be used. The same applies to the second engine speed Ne2 and the third engine speed Ne3.

  Further, in the above-described embodiment, the differential mechanism is constituted by the planetary gear device 26, the sun gear S0 (first rotating element) of the planetary gear device 26 is the first electric motor MG1, and the carrier CA0 (second rotating element) is the engine 24. The ring gear R0 (third rotating element) is connected to the drive wheel 18, but the differential mechanism is not limited to the planetary gear device, and the connection configuration is not limited to this embodiment and may be changed as appropriate. Absent.

  In the above-described embodiment, the variable valve mechanism 25 is configured to be able to adjust the valve timing and the valve lift amount of the valve, and is decompressed by adjusting the valve timing and the valve lift amount. The variable valve mechanism 25 only needs to be configured so that either one of the valve timing and the valve lift amount can be adjusted. The variable valve mechanism 25 may control and decompress (depressurize) one of these.

  In the above-described embodiment, the decompression for reducing the pressure in the cylinder of the engine 24 is performed to narrow the rotational speed region where NV deteriorates. However, the decompression is not necessarily performed, and the decompression is performed. You don't have to.

  In the above-described embodiment, the sun gear S0, which is the first rotating element, is directly connected to the first electric motor MG1, but may be connected so as to be able to transmit power via a gear, a belt wheel, or the like. Further, the carrier CA0 as the second rotating element is connected to the engine 24 via the damper device 38, but may be further connected so as to be able to transmit power via a gear, a belt wheel or the like. Further, the ring gear R0, which is the third rotating element, is connected to the drive wheel 18 via the differential gear device 16, but may be further connected to be able to transmit power via a gear, a belt wheel, or the like.

  In the above-described embodiment, the engine rotational speed Ne is maintained at a constant value at the target rotational speed Ne *, but is not necessarily limited to a constant value. In the present invention, if the engine rotational speed Ne during engine braking is maintained at a rotational speed higher than the NV worsening rotational speed region, even if a rotational speed change occurs, it is allowed. Also, when passing through the NV worsening rotation speed region, the command value drops rapidly, but this command value may have a predetermined gradient.

  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.

8: Hybrid vehicle 18: Drive wheel 24: Engine 25: Variable valve mechanism 26: Planetary gear unit (differential mechanism)
32: Power storage device (battery)
38: Damper device 100: Electronic control device (control device)
MG1: First motor (motor)
S0: Sun gear (first rotating element)
CA0: carrier (second rotating element)
R0: Ring gear (third rotating element)
P0: Pinion gear

Claims (3)

A differential mechanism comprising a first rotating element connected to the electric motor, a second rotating element connected to the engine, and a third rotating element connected to the drive wheel; and between the engine and the electric motor And a damper device interposed on the power transmission path of the hybrid vehicle, wherein the engine rotation speed of the engine can be controlled by the electric motor,
The engine includes a variable valve mechanism capable of changing at least one of a valve timing of the engine and a valve lift amount of the engine,

When the engine speed is controlled to be lower than the resonance speed range during engine braking , the pressure in the cylinder of the engine is reduced by controlling at least one of the valve timing and the valve lift amount. Then, after changing the resonance rotational speed region to a low rotational speed side and maintaining the engine rotational speed at a rotational speed higher than the resonant rotational speed region, the hybrid vehicle is characterized in that the engine rotational speed is decreased. Control device. The differential mechanism is composed of a planetary gear device,
When lowering the engine rotation speed to a lower rotation speed than the resonance rotation speed region, the higher the rotation speed of the pinion gear of the planetary gear device, the higher the rotation speed than the resonance rotation speed region compared to the lower case. 2. The control apparatus for a hybrid vehicle according to claim 1, wherein the time for maintaining is long.   The engine rotational speed is maintained at a higher rotational speed than the resonance rotational speed region when charging of a battery that exchanges electric power with the electric motor is restricted. Hybrid vehicle control device.

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