JP5867219B2 - Hybrid vehicle - Google Patents

Description

  The present invention relates to a hybrid vehicle that travels while controlling an internal combustion engine and an electric motor.

  A hybrid vehicle is equipped with an internal combustion engine and an electric motor as a driving source that generates a driving force for driving the vehicle. That is, the hybrid vehicle travels by transmitting torque generated by at least one of the engine and the electric motor to the drive shaft connected to the drive wheels of the vehicle. Hereinafter, the internal combustion engine is also simply referred to as “engine”.

  In such a hybrid vehicle, a torque required for the drive shaft of the hybrid vehicle (that is, user request torque) is determined according to the amount of accelerator operation by the user, and the user request torque and the rotation speed of the drive shaft (that is, vehicle speed). The user request output is determined based on a value corresponding to the product of the equivalent value). Next, the hybrid vehicle calculates an engine request output based on the user request output, and outputs the engine request output from the engine. At this time, the engine output torque Te and the engine rotational speed Ne are determined so that the engine can be operated most efficiently. That is, the hybrid vehicle outputs an output equal to the engine required output from the engine while adjusting the operation state of the engine (the engine output torque Te and the engine rotational speed Ne) so that the engine can be operated most efficiently. . Then, the motor is driven so that the torque that is insufficient relative to the user request torque when the torque based on the engine output torque Te acts on the drive shaft is compensated by the torque output by the motor.

  Further, the hybrid vehicle performs intermittent operation for intermittently stopping the operation of the engine. For example, the hybrid vehicle stops the operation of the engine when the engine required output is smaller than the engine stop threshold value and therefore the engine cannot be operated efficiently. Further, the hybrid vehicle starts the operation of the engine when the engine required output becomes larger than the engine start threshold value while the engine is stopped, and therefore the engine can be operated efficiently.

  However, in a hybrid vehicle that performs such intermittent operation, when the user frequently changes the accelerator operation amount when the engine is stopped (for example, when an operation that increases the accelerator operation amount and then immediately decreases it). The engine is started once but then stopped immediately. In this case, the amount of work performed by the engine during the period of operation of the engine is extremely small. On the other hand, fuel and electric power are consumed for starting the engine. As a result, the fuel efficiency of the hybrid vehicle may deteriorate due to intermittent operation.

  Therefore, in the conventional hybrid vehicle, when the accelerator operation amount is increased when the vehicle speed is decreasing or when the accelerator operation amount is decreased when the vehicle speed is constant or increasing (that is, the opening change condition) If the engine is in operation until the fixed time has elapsed from that point in time, the engine is maintained in a self-sustained operation state and is continuously operated. (For example, refer to Patent Document 1).

JP 2010-234872 A

  According to the above-described conventional hybrid vehicle, for example, if the opening change condition is satisfied when the engine is stopped, the engine is not started until a certain time has elapsed from that point. Therefore, if the user increases the accelerator operation amount to a large value while the engine is stopped, or if the user desires continuous acceleration, the accelerator operation amount is maintained at a relatively large value. Even if the engine is running, the engine is not started until a certain period of time has elapsed, so the hybrid vehicle may not be able to accelerate sufficiently.

  Further, according to the conventional hybrid vehicle, for example, when the opening change condition is satisfied while the engine is in operation, the engine is not stopped until a certain time has elapsed from that point. Therefore, even when the user returns the accelerator operation amount to “0” during engine operation, the engine operation is continued unnecessarily, and as a result, fuel consumption may deteriorate.

  The present invention has been made to address the above-described problems. That is, one of the objects of the present invention is that the user truly requests acceleration while avoiding starting the engine when the user performs an operation that slightly increases the accelerator operation amount for a short time. In such a case, it is an object of the present invention to provide a hybrid vehicle capable of starting the engine and satisfying the user's acceleration request by the output of the engine.

  A hybrid vehicle according to the present invention includes an internal combustion engine, an electric motor, a drive shaft of the vehicle, and a power transmission mechanism that couples the engine to the torque transmission and also connects the drive shaft and the electric motor to allow torque transmission, and a control. An apparatus.

The controller is
When the engine demand output determined according to the amount of accelerator operation by the user becomes larger than the engine start threshold value while the engine is stopped, the engine operation is started, and the engine demand output is stopped while the engine is running. A torque equal to a user request torque, which is a torque required for the drive shaft determined according to the user's accelerator operation amount, is executed while performing an intermittent operation to stop the operation of the engine when it becomes smaller than a threshold value. The output shaft and the output torque of the electric motor are controlled to act on the drive shaft.

Furthermore, the control device comprises:
When the engine is stopped, the engine start threshold value is set so that the engine start threshold value decreases as the duration of the state in which the accelerator operation amount is not zero is longer.

  According to this, when the engine is stopped, immediately after the user slightly increases the accelerator operation amount from zero, the duration of the state in which the accelerator operation amount is not zero is short. Set to a large value. Therefore, when the user immediately returns the accelerator operation amount to zero, the engine request output determined according to the user's accelerator operation amount does not become larger than the engine start threshold value. As a result, the engine is not started and remains in a stopped state, so that fuel and electric power are not consumed for starting the engine. Therefore, the fuel consumption does not deteriorate.

  On the other hand, when the engine is stopped, when the user greatly increases the accelerator operation amount from zero, the engine request output determined according to the user's accelerator operation amount becomes larger than the engine start threshold value. As a result, the engine is immediately started and the engine output is used to accelerate the vehicle. As a result, the user's acceleration request can be satisfied.

  On the other hand, when the engine is stopped, if the user maintains the state where the accelerator operation amount is slightly increased from zero, the duration time in which the accelerator operation amount is not zero becomes longer. Accordingly, since the engine start threshold value gradually decreases, the engine is started when this state continues to some extent. As a result, if the user wants continuous acceleration, the engine output can be used to meet that acceleration requirement.

In the hybrid vehicle of the present invention,
The controller is
If the engine is operated, it is preferable to be configured to the duration of a state where the engine is operated to set the aircraft function stop threshold value so that the engine stop threshold longer increases .

  According to this, immediately after the engine is started, the engine operation threshold is short, and therefore the engine stop threshold is small. Therefore, the engine operation is not stopped unless the user greatly decreases the accelerator operation amount. As a result, frequent stopping and starting of the engine can be avoided. That is, it is possible to prevent deterioration in fuel consumption due to the engine being operated only for a short time.

  Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of each embodiment of the present invention described with reference to the following drawings.

FIG. 1 is a schematic view of a hybrid vehicle according to an embodiment of the present invention. FIG. 2 is a flowchart showing a routine executed by the CPU of the power management ECU shown in FIG. FIG. 3 is a graph showing the relationship between the accelerator operation amount and the vehicle speed, and the user request torque. FIG. 4 is an engine start threshold value lookup table (map) referred to by the CPU of the power management ECU shown in FIG. FIG. 5 is a graph showing the relationship between the engine speed and the engine output torque and the optimum engine operation line. FIG. 6 is a collinear diagram of the planetary gear device during travel of the hybrid vehicle. FIG. 7 is a look-up table (map) of the engine start threshold value referred to by the CPU of the power management ECU shown in FIG.

  Hereinafter, a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings.

<First Embodiment>
(Constitution)
As shown in FIG. 1, the hybrid vehicle 10 according to the first embodiment of the present invention includes a first generator motor MG1, a second generator motor MG2, an internal combustion engine 20, a power distribution mechanism 30, a drive force transmission mechanism 50, a first 1 inverter 61, second inverter 62, boost converter 63, battery 64 as a power storage device, power management ECU 70, battery ECU 71, motor ECU 72, engine ECU 73, and the like.

  The ECU is an abbreviation for an electric control unit, and is an electronic control circuit having a microcomputer including a CPU, a ROM, a RAM, a backup RAM (or nonvolatile memory), an interface, and the like as main components. The backup RAM can hold data regardless of whether an ignition key switch (not shown) of the vehicle 10 is on or off.

  The first generator motor (motor generator) MG1 is a synchronous generator motor that can function as both a generator and a motor. The first generator motor MG1 mainly functions as a generator in this example. The first generator motor MG1 includes a first shaft 41 as an output shaft.

  Similarly to the first generator motor MG1, the second generator motor (motor generator) MG2 is a synchronous generator motor that can function as either a generator or an electric motor. In this example, the second generator motor MG2 mainly functions as a motor. The second generator motor MG2 includes a second shaft 42 as an output shaft.

  The engine 20 is a four-cycle, spark ignition type, multi-cylinder, internal combustion engine. The engine 20 includes an intake passage 21 including an intake pipe and an intake manifold, a throttle valve 22, a throttle valve actuator 22a, a plurality of fuel injection valves 23, a plurality of ignition devices 24 including an ignition plug, and a crank that is an output shaft of the engine 20 A shaft 25, an exhaust manifold 26, an exhaust pipe 27, an upstream three-way catalyst 28, and a downstream three-way catalyst 29 are included. The engine 20 may include a variable intake valve control device (VVT) (not shown).

The throttle valve 22 is rotatably supported by the intake passage portion 21.
The throttle valve actuator 22a rotates the throttle valve 22 in response to an instruction signal from the engine ECU 73, so that the passage sectional area of the intake passage portion 21 can be changed.
Each of the fuel injection valves 23 is disposed in the intake port of each cylinder so as to correspond to each cylinder, and can change the fuel injection amount in response to an instruction signal from the engine ECU 73.

  Each of the ignition devices 24 including the ignition plug is configured to generate an ignition spark at a predetermined timing in the combustion chamber of each cylinder in response to an instruction signal from the engine ECU 73.

  The three-way catalyst 28 on the upstream side is an exhaust purification catalyst, and is disposed in the exhaust collecting portion of the exhaust manifold 26. That is, the catalyst 28 is provided in the exhaust passage of the engine 20. The three-way catalyst simultaneously purifies unburned substances (HC, CO, etc.) and NOx discharged from the engine 20.

  The downstream side three-way catalyst 29 is an exhaust purification catalyst, and is provided in an exhaust pipe 27 connected to an exhaust manifold portion of the exhaust manifold 26.

  The engine 20 changes the fuel injection amount, changes the intake air amount by changing the opening degree of the throttle valve 22 by the throttle valve actuator 22a, etc., and the torque generated by the engine 20 and the engine rotational speed. (Thus, the engine output) can be changed.

  The power distribution mechanism 30 includes a known planetary gear device 31. The planetary gear device 31 includes a sun gear 32, a plurality of planetary gears 33, and a ring gear 34.

  The sun gear 32 is connected to the first shaft 41 of the first generator motor MG1. Accordingly, the first generator motor MG1 can output torque to the sun gear 32. Further, the first generator motor MG1 can be driven to rotate by torque input from the sun gear 32 to the first generator motor MG1 (first shaft 41). The first generator motor MG1 can generate electric power by being rotationally driven by the torque input from the sun gear 32 to the first generator motor MG1.

  Each of the plurality of planetary gears 33 meshes with the sun gear 32 and meshes with the ring gear 34. The planetary gear 33 has a rotation shaft (spinning shaft) provided on the planetary carrier 35. The planetary carrier 35 is held so as to be rotatable coaxially with the sun gear 32. Therefore, the planetary gear 33 can revolve while rotating on the outer periphery of the sun gear 32. The planetary carrier 35 is connected to the crankshaft 25 of the engine 20. Therefore, the planetary gear 33 can be rotationally driven by the torque input from the crankshaft 25 to the planetary carrier 35.

  The ring gear 34 is held so as to be rotatable coaxially with the sun gear 32.

  As described above, the planetary gear 33 meshes with the sun gear 32 and the ring gear 34. Therefore, when torque is input from the planetary gear 33 to the sun gear 32, the sun gear 32 is rotationally driven by the torque. When torque is input from the planetary gear 33 to the ring gear 34, the ring gear 34 is rotationally driven by the torque. Conversely, when torque is input from the sun gear 32 to the planetary gear 33, the planetary gear 33 is rotationally driven by the torque. When torque is input from the ring gear 34 to the planetary gear 33, the planetary gear 33 is rotationally driven by the torque.

  The ring gear 34 is connected to the second shaft 42 of the second generator motor MG2 via the ring gear carrier 36. Therefore, the second generator motor MG <b> 2 can output torque to the ring gear 34. Further, the second generator motor MG2 can be driven to rotate by torque input from the ring gear 34 to the second generator motor MG2 (second shaft 42). The second generator motor MG2 can generate electric power by being rotationally driven by the torque input from the ring gear 34 to the second generator motor MG2.

  Further, the ring gear 34 is connected to an output gear 37 via a ring gear carrier 36. Accordingly, the output gear 37 can be rotationally driven by the torque input from the ring gear 34 to the output gear 37. The ring gear 34 can be rotationally driven by torque input from the output gear 37 to the ring gear 34.

  The drive force transmission mechanism 50 includes a gear train 51, a differential gear 52, and a drive shaft (drive shaft) 53.

  The gear train 51 connects the output gear 37 and the differential gear 52 by a gear mechanism so that power can be transmitted. The differential gear 52 is attached to the drive shaft 53. Drive wheels 54 are attached to both ends of the drive shaft 53. Accordingly, the torque from the output gear 37 is transmitted to the drive wheels 54 via the gear train 51, the differential gear 52, and the drive shaft 53. The hybrid vehicle 10 can travel by the torque transmitted to the drive wheels 54.

  The first inverter 61 is electrically connected to the first generator motor MG <b> 1 and the boost converter 63. Therefore, when the first generator motor MG1 is generating power, the electric power generated by the first generator motor MG1 is supplied to the battery 64 via the first inverter 61 and the boost converter 63. Conversely, the first generator motor MG1 is driven to rotate by the electric power supplied from the battery 64 via the boost converter 63 and the first inverter 61.

  The second inverter 62 is electrically connected to the second generator motor MG <b> 2 and the boost converter 63. Therefore, when the second generator motor MG2 is generating power, the electric power generated by the second generator motor MG2 is supplied to the battery 64 via the second inverter 62 and the boost converter 63. On the contrary, the second generator motor MG2 is driven to rotate by the electric power supplied from the battery 64 via the boost converter 63 and the second inverter 62.

  Furthermore, the electric power generated by the first generator motor MG1 can be directly supplied to the second generator motor MG2, and the electric power generated by the second generator motor MG2 can be directly supplied to the first generator motor MG1.

  The battery 64 is a lithium ion battery in this example. However, the battery 64 may be a power storage device that can be discharged and charged, and may be a nickel metal hydride battery or another secondary battery.

  The power management ECU 70 (hereinafter referred to as “PM ECU 70”) is connected to the battery ECU 71, the motor ECU 72, and the engine ECU 73 so as to exchange information by communication.

  The PM ECU 70 is connected to a power switch 81, a shift position sensor 82, an accelerator operation amount sensor 83, a brake switch 84, a vehicle speed sensor 85, and the like, and inputs output signals generated by these sensors.

  The power switch 81 is a system activation switch for the hybrid vehicle 10. The PM ECU 70 is configured to start the system (become Ready-On state) when the power switch 81 is operated when a vehicle key (not shown) is inserted into the key slot and the brake pedal is depressed. ing.

  The shift position sensor 82 generates a signal indicating a shift position selected by a shift lever (not shown) provided near the driver's seat of the hybrid vehicle 10 so as to be operable by the driver. The shift position includes P (parking position), R (reverse drive position), N (neutral position), and D (travel position).

The accelerator operation amount sensor 83 generates an output signal indicating an operation amount (accelerator operation amount AP) of an accelerator pedal (not shown) provided so as to be operable by the driver. The accelerator operation amount AP can also be expressed as an acceleration operation amount. When the accelerator pedal is not operated, the accelerator operation amount AP is zero (“0”).
The brake switch 84 generates an output signal indicating that the brake pedal is in an operated state when a brake pedal (not shown) that can be operated by the driver is operated.
The vehicle speed sensor 85 generates an output signal representing the vehicle speed SPD of the hybrid vehicle 10.

  The PM ECU 70 inputs a remaining capacity SOC (State Of Charge) of the battery 64 calculated by the battery ECU 71. Since the remaining capacity SOC is a parameter having a correlation with the remaining capacity of the battery 64, it is also referred to as a remaining capacity related parameter. The remaining capacity SOC is calculated by a known method based on the integrated value of the current flowing into and out of the battery 64 and the like.

  The PM ECU 70 further receives an instantaneous output Wout (unit: W) of the battery 64 calculated by the battery ECU 71. The instantaneous output Wout is also referred to as a battery instantaneous output Wout. The battery instantaneous output Wout is an upper limit value of power that the battery 64 can output per unit time. The battery instantaneous output Wout has a correlation with the remaining capacity SOC, and is substantially constant when the remaining capacity SOC is equal to or greater than a predetermined value (for example, 40%), and the remaining capacity SOC is small when the remaining capacity SOC is less than the predetermined value. It gets smaller.

  The PM ECU 70 receives a signal representing the rotational speed of the first generator motor MG1 (hereinafter referred to as “MG1 rotational speed Nm1”) and the rotational speed of the second generator motor MG2 (hereinafter referred to as “MG2 rotational speed”) via the motor ECU 72. Nm2 ”) is input.

  The MG1 rotation speed Nm1 is calculated by the motor ECU 72 based on “the output value of the resolver 96 that is provided in the first generator motor MG1 and outputs an output value corresponding to the rotation angle of the rotor of the first generator motor MG1”. ing. Similarly, the MG2 rotation speed Nm2 is calculated by the motor ECU 72 based on “the output value of the resolver 97 provided in the second generator motor MG2 and outputting the output value corresponding to the rotation angle of the rotor of the second generator motor MG2”. Has been.

  The PM ECU 70 inputs various output signals representing the engine state via the engine ECU 73. The output signal representing the engine state includes the engine speed Ne, the throttle valve opening degree TA, the engine coolant temperature THW, and the like.

  The motor ECU 72 is connected to the first inverter 61, the second inverter 62 and the boost converter 63. The motor EC 72 is configured to send an instruction signal to these based on commands from the PM ECU 80 (“MG1 command torque Tm1 * and MG2 command torque Tm2 *, which will be described later). The first generator motor MG1 is controlled using the inverter 61 and the boost converter 63, and the second generator motor MG2 is controlled using the second inverter 62 and the boost converter 63.

  The engine ECU 73 is connected to the “throttle valve actuator 22a, fuel injection valve 23, ignition device 24, etc.” which are engine actuators, and sends instruction signals to them. Further, the engine ECU 73 is connected to an air flow meter 91, a throttle valve opening sensor 92, a cooling water temperature sensor 93, an engine speed sensor 94, an air-fuel ratio sensor 95, and the like so as to acquire output signals generated by these. It has become.

The air flow meter 91 measures the amount of air per unit time taken into the engine 20 and outputs a signal representing the amount of air (intake air flow rate) Ga.
The throttle valve opening sensor 92 detects the opening (throttle valve opening) of the throttle valve 22 and outputs a signal representing the detected throttle valve opening TA.
The coolant temperature sensor 93 detects the coolant temperature of the engine 20 and outputs a signal representing the detected coolant temperature THW. The cooling water temperature THW is a parameter having a strong correlation with the temperature of the catalyst 28 and is also referred to as a catalyst temperature parameter.

  The engine rotation speed sensor 94 generates a pulse signal every time the crankshaft 25 of the engine 20 rotates by a predetermined angle. The engine ECU 73 acquires the engine rotational speed Ne based on this pulse signal.

  The air-fuel ratio sensor 95 is an exhaust collecting portion of the exhaust manifold 26 and is disposed upstream of the upstream side three-way catalyst 28. The air fuel ratio sensor 95 is a so-called “limit current type wide area air fuel ratio sensor”. The air-fuel ratio sensor 95 detects the air-fuel ratio of the exhaust gas, and outputs the detected air-fuel ratio (detected air-fuel ratio) abyfs of the exhaust gas. Note that the detected air-fuel ratio abyfs increases as the air-fuel ratio of the exhaust gas increases (becomes leaner).

  The engine ECU 73 instructs the “throttle valve actuator 22a, fuel injection valve 23, and ignition device 24 (and a variable intake valve control device not shown)” based on signals acquired from these sensors and the command from the PM ECU 70. The engine 20 is controlled by sending a signal. The engine 20 is provided with a cam position sensor (not shown). The engine ECU 73 obtains the crank angle (absolute crank angle) of the engine 20 with reference to the intake top dead center of a specific cylinder based on signals from the engine rotational speed sensor 94 and the cam position sensor. .

(Operation: Drive control)
Next, the operation of the hybrid vehicle 10 will be described. The processing described below is executed by the “CPU of the PM ECU 70 and the CPU of the engine ECU 73”. However, in the following, in order to simplify the description, the CPU of the PM ECU 70 is denoted as “PM”, and the CPU of the engine ECU 73 is denoted as “EG”.

  PM and EG operate the hybrid vehicle 10 by controlling the operation of the first generator motor MG1, the second generator motor MG2, and the engine 20 in cooperation with each other. As will be described later, these controls are performed, for example, in Japanese Unexamined Patent Application Publication No. 2009-126450 (US Publication No. US2010 / 0241297) except that the start condition (operation start condition) and the operation stop condition of the engine 20 are variable. And JP-A-9-308812 (US Pat. No. 6,131,680 filed on Mar. 10, 1997) and the like. These are incorporated herein by reference.

  When the shift position is at the travel position, the PM executes the “drive control routine” shown by the flowchart in FIG. 2 every time a predetermined time elapses. Therefore, at a predetermined timing, the PM starts processing from step 200 in FIG. 2 and sequentially performs the processing from step 205 to step 220 described below.

  Step 205: The PM acquires the ring gear required torque Tr * based on the accelerator operation amount AP and the vehicle speed SPD. Furthermore, PM determines the user request output Pr * based on the ring gear request torque Tr *.

  More specifically, the torque acting on the drive shaft 53 (drive shaft torque) and the torque acting on the rotating shaft of the ring gear 34 are in a proportional relationship. Therefore, the user request torque Tu * requested by the user for traveling of the hybrid vehicle 10 and the ring gear request torque Tr * are in a proportional relationship.

  Therefore, PM refers to “the relationship between the accelerator operation amount AP and the vehicle speed SPD and the user request torque Tu *” shown in FIG. 3 as “the accelerator operation amount AP and the vehicle speed SPD, the ring gear request torque Tr *, The table converted into “relationship between” is stored in the ROM as a torque map MapTr * (AP, SPD). Then, the PM acquires the ring gear required torque Tr * by applying the current “accelerator operation amount AP and vehicle speed SPD” to the torque map MapTr * (AP, SPD). Thus, the user request torque Tu * is “torque required for the drive shaft 53 (vehicle request drive force)” determined according to the user's accelerator operation amount AP, and the ring gear request torque Tr * is also the user's accelerator operation. The required torque is determined according to the amount AP.

  On the other hand, the output (power) required for the drive shaft 53 is equal to the product (Tu * · SPD) of the user requested torque Tu * and the actual vehicle speed SPD. This product (Tu * · SPD) is equal to the product (Tr * · Nr) of the ring gear required torque Tr * and the rotational speed Nr of the ring gear 34. Therefore, hereinafter, the product (Tr * · Nr) is referred to as “user request output Pr *”. That is, the user request output Pr * is an output determined based on the user request torque Tu *.

  Step 210: The PM acquires a battery charge request output Pb * based on the remaining capacity SOC. The battery charge request output Pb * is a value corresponding to the power to charge the battery 63 or the power to be discharged from the battery 63 in order to maintain the remaining capacity SOC in the vicinity of the predetermined remaining capacity center value SOCcent.

  Step 215: The PM obtains a value (Pr * + Pb * + Ploss) obtained by adding the loss Ploss to the sum of the user request output Pr * and the battery charge request output Pb * as the engine request output Pe *. The engine required output Pe * is an output required for the engine 20.

  Step 220: The PM determines whether the operation of the engine 20 is stopped (whether the engine is stopped).

(Case 1: When the operation of the engine 20 is stopped)
Now, it is assumed that the operation of the engine 20 is stopped. In this case, PM determines “Yes” in step 220 and proceeds to step 225 to calculate the engine start threshold value Peonth. More specifically, the PM ECU 70 stores the “look-up table MapPeonth (SPD, Tacon) defining the relationship between the vehicle speed SPD and accelerator pedal ON time Tacon and the engine start threshold value Peonth” shown in FIG. I remember it. The accelerator pedal ON time Tacon is a duration time in a state where the accelerator pedal is depressed, that is, a state where the accelerator operation amount AP is not “0”. PM separately acquires the accelerator pedal ON time Tacon by a routine (not shown).

  PM acquires the engine start threshold value Peonth by applying the actual vehicle speed SPD and accelerator pedal ON time Tacon to the table MapPeonth (SPD, Tacon) shown in FIG. According to this table MapPeonth (SPD, Tacon), the engine start threshold value Peonth is determined so as to increase as the accelerator pedal ON time Tacon decreases. In other words, the engine start threshold value Peonth is determined so as to decrease as the accelerator pedal ON time Tacon increases.

  Furthermore, according to this table MapPeonth (SPD, Tacon), the engine start threshold value Peonth is determined so as to decrease as the vehicle speed SPD increases. However, the engine start threshold value Peonth may be increased or decreased as the vehicle speed SPD increases.

  Next, the PM proceeds to step 230 in FIG. 2 and determines whether or not the engine request output Pe * is larger than “the engine start threshold value Peonth determined in step 225”.

  If the engine request output Pe * is larger than the engine start threshold value Peonth, the PM determines “Yes” in step 230 and proceeds to step 235 to transmit an instruction to start operation of the engine 20 (start instruction) to the engine ECU 73. To do. The engine ECU 73 starts the engine 20 based on this instruction. Accordingly, the condition that the engine required output Pe * is larger than the engine start threshold value Peonth is the engine start condition. Thereafter, the PM sequentially performs the processing from step 240 to step 265 described below, proceeds to step 295, and once ends this routine.

  Step 240: The PM operates the engine 20 so that an output equal to the engine required output Pe * is output from the engine 20 and the operating efficiency of the engine 20 is the best. That is, the PM determines the target engine output torque Te * and the target engine rotation speed Ne * based on the optimum engine operating point corresponding to the engine required output Pe *.

  More specifically, an engine operating point at which the operating efficiency (fuel consumption) of the engine 20 is optimal when a certain output is output from the crankshaft 25 is determined in advance as an optimal engine operating point for each output by experiments or the like. Yes. These optimum engine operating points are plotted on a graph defined by the engine output torque Te and the engine rotational speed Ne, and a line formed by connecting these plots is obtained as the optimum engine operating line. The optimum engine operating line thus obtained is indicated by a solid line Lopt in FIG. In FIG. 5, each of a plurality of lines C0 to C5 indicated by broken lines is a line (equal output line) connecting engine operating points at which the same output can be output from the crankshaft 25.

  The PM searches for an optimal engine operating point at which an output equal to the engine required output Pe * is obtained, and the “engine output torque Te and engine rotational speed Ne” corresponding to the searched optimal operating point is set to “target engine output torque Te * And target engine speed Ne * ". For example, when the engine required output Pe * is equal to the output corresponding to the line C2 in FIG. 5, the engine output torque Te1 for the intersection P1 between the line C2 and the solid line Lopt is determined as the target engine output torque Te *, and the engine for the intersection P1 The rotational speed Ne1 is determined as the target engine rotational speed Ne *.

Step 245: The PM substitutes “second MG rotation speed Nm2 equal to the rotation speed Nr” as the rotation speed Nr of the ring gear 34 in the following equation (1), and sets the target engine rotation speed Ne * as the engine rotation speed Ne. By substituting, “MG1 target rotational speed Nm1 * equal to the target rotational speed Ns * of the sun gear 32” is calculated.

Ns = Nr− (Nr−Ne) · (1 + ρ) / ρ (1)
(Nm1 * = Nm2- (Nm2-Ne *) · (1 + ρ) / ρ)

In the above equation (1), “ρ” is a value defined by the following equation (2). That is, “ρ” is the number of teeth of the sun gear 32 with respect to the number of teeth of the ring gear 34.

ρ = (number of teeth of sun gear 32 / number of teeth of ring gear 34) (2)

  Here, the basis of the equation (1) will be briefly described. The relationship between the rotational speeds of the respective gears in the planetary gear unit 31 is represented by a well-known collinear chart shown in FIG. The straight line shown in the nomograph is referred to as an operation collinear L. As can be understood from this nomograph, the difference (Ne) between the engine rotational speed Ne and the rotational speed Ns of the sun gear 32 with respect to the difference (Nr−Ns) between the rotational speed Nr of the ring gear 34 and the rotational speed Ns of the sun gear 32. -Ns) ratio (= (Ne-Ns) / (Nr-Ns)) is equal to the ratio of 1 to the value (1 + ρ) (= 1 / (1 + ρ)). Based on this proportional relationship, the above equation (1) is derived.

Further, PM calculates MG1 command torque Tm1 * which is torque to be output to first generator motor MG1 in accordance with the following equation (3) in step 245 of FIG. In the equation (3), the value PID (Nm1 * −Nm1) is a feedback amount corresponding to the difference between “MG1 target rotational speed Nm1 * and the actual rotational speed Nm1 of the first generator motor MG1”. That is, the value PID (Nm1 * −Nm1) is a feedback amount for making the actual rotational speed Nm1 coincide with the MG1 target rotational speed Nm1 *.

Tm1 * = Te *. (Ρ / (1 + ρ)) + PID (Nm1 * −Nm1) (3)

Here, the basis of the above equation (3) will be described. When a torque equal to the target engine output torque Te * is generated on the crankshaft 25 (that is, when the engine output torque is Te *), the engine output torque Te * is torque-converted by the planetary gear unit 31. . As a result, the engine output torque Te * acts on the rotating shaft of the sun gear 32 as torque Tes expressed by the following equation (4), and the torque expressed by the following equation (5) on the rotating shaft of the ring gear 34. Acts as Ter.

Tes = Te * · (ρ / (1 + ρ)) (4)

Ter = Te * · (1 / (1 + ρ)) (5)

In order for the operation collinearity to be stable, the force of the operation collinearity should be balanced. Therefore, as shown in FIG. 6, the torque Tm1 having the same magnitude and the opposite direction as the torque Tes obtained by the above equation (4) is applied to the rotation shaft of the sun gear 32, and the rotation of the ring gear 34 is performed. A torque Tm2 expressed by the following equation (6) may be applied to the shaft. That is, the torque Tm2 is equal to the shortage of the torque Ter with respect to the ring gear required torque Tr *. This torque Tm2 is adopted as MG2 command torque Tm2 * in step 250 of FIG.

Tm2 = Tr * −Ter (6)

  On the other hand, if the sun gear 32 rotates at the target rotational speed Ns * (that is, if the actual rotational speed Nm1 of the first generator motor MG1 coincides with the MG1 target rotational speed Nm1 *), the engine rotational speed Ne becomes the target engine rotational speed. It corresponds to the speed Ne *. From the above, the MG1 command torque Tm1 * is obtained by the above equation (3).

Step 250: The PM calculates an MG2 command torque Tm2 *, which is a torque to be output to the second generator motor MG2, according to the above equations (5) and (6). PM may determine the MG2 command torque Tm2 * based on the following equation (7).

Tm2 * = Tr * −Tm1 * / ρ (7)

  Step 255: The PM sends a command signal to the EG so that the engine 20 is operated at the optimum engine operating point (in other words, the engine output torque becomes the target engine output torque Te *). As a result, the EG changes the opening of the throttle valve 22 by the throttle valve actuator 22a, changes the fuel injection amount accordingly, and changes the engine 20 so that the engine output torque Te becomes the target engine output torque Te *. Control.

Step 260: PM transmits MG1 command torque Tm1 * to motor ECU 72. The motor ECU 72 controls the first inverter 61 and the boost converter 63 so that the torque generated by the first generator motor MG1 coincides with the MG1 command torque Tm1 *.
Step 265: PM transmits MG2 command torque Tm2 * to motor ECU 72. The motor ECU 72 controls the second inverter 62 and the boost converter 63 so that the torque generated by the second generator motor MG2 matches the MG2 command torque Tm2 *.

  With the above processing, a torque equal to the ring gear required torque Tr * is applied to the ring gear 34 by the engine 20 and the second generator motor MG2. Furthermore, when the remaining capacity SOC is smaller than the predetermined value SOCLoth, the output generated by the engine 20 is increased by the battery charge request output Pb *. Accordingly, the torque Ter increases, so that the MG2 command torque Tm2 * decreases as can be understood from the equation (6). As a result, since the electric power consumed by the second generator motor MG2 is reduced among the electric power generated by the first generator motor MG1, surplus power generated by the first generator motor MG1 (not consumed by the second generator motor MG2). The battery 64 is charged by the power.

  On the other hand, if the engine request output Pe * is equal to or less than the engine start threshold value Peonth at the time when the PM executes the process of step 230, the PM determines “No” in step 230 and proceeds to step 270. The MG1 command torque Tm1 * is set to “0”. Next, the PM proceeds to step 275 and sets the ring gear required torque Tr * to the MG2 command torque TM2 *. Thereafter, the PM executes the processing of step 260 and step 265 described above. As a result, the engine 20 is not started (the operation stop state is maintained), and the user request torque Tu * is satisfied only by the torque generated by the second generator motor MG2.

(Case 2: When the operation of the engine 20 is not stopped)
Assume that the engine 20 is now operating. In this case, PM determines “No” in step 220 and proceeds to step 280 to calculate the engine stop threshold value Peoffth. More specifically, the PM ECU 70 performs the look-up table MapPeoffth (SPD, Tegon defining the relationship between the vehicle speed SPD and the engine operation time (engine operation continuation time) Tegon and the engine stop threshold value Peoffth shown in FIG. ) "Is stored in the ROM. The engine operation time Tegon is an operation continuation time of the engine 20 (a time during which the operation is continued after the engine 20 is started). PM separately acquires the engine operation time Tegon by a routine not shown.

  The PM acquires the engine stop threshold value Peoffth by applying the actual vehicle speed SPD and the engine operation time Tegon to the table MapPeoffth (SPD, Tegon) shown in FIG. According to this table MapPeoffth (SPD, Tegon), the engine stop threshold value Peoffth is determined so as to increase as the engine operation time Tegon increases. In other words, the engine stop threshold value Peoffth is determined so as to become smaller as the engine operation time Tegon is shorter.

  Further, according to this table MapPeoffth (SPD, Tegon), the engine stop threshold value Peoffth is determined so as to decrease as the vehicle speed SPD increases. However, the engine stop threshold value Peoffth may be increased or decreased as the vehicle speed SPD increases.

  Next, the PM proceeds to step 285 in FIG. 2 and determines whether or not the engine request output Pe * is smaller than the “engine stop threshold value Peoffth determined in step 280”.

  If the engine required output Pe * is smaller than the engine stop threshold value Peoffth, the PM determines “Yes” in step 285 and proceeds to step 290 to give an instruction to the engine ECU 73 to stop the operation of the engine 20 (operation stop instruction). Send. The engine ECU 73 stops the operation of the engine 20 based on this instruction. Therefore, the condition that the engine required output Pe * is smaller than the engine stop threshold value Peoffth is an engine stop condition. Thereafter, the PM performs the processing of step 270, step 275, step 260, and step 265, proceeds to step 295, and once ends this routine.

  As a result, the operation of the engine 20 is stopped, and the user request torque Tu * is satisfied only by the torque generated by the second generator motor MG2.

  On the other hand, if the engine request output Pe * is equal to or greater than the engine stop threshold value Peoffth at the time when the PM executes the process of step 285, the PM is determined to be “No” in step 285, and steps 240 to 265 are performed. Process in order. As a result, the operation of the engine 20 is continued, and the user request output Pr * is satisfied by the torque generated by the engine 20 and the second generator motor MG2.

As described above, the hybrid vehicle 10 according to the embodiment of the present invention is
An internal combustion engine 20;
An electric motor (second generator motor MG2);
A power storage device (battery 64) capable of supplying electric power for driving the motor to the motor;
A generator (first generator motor MG1) capable of generating electric power for charging the power storage device using the output of the engine 20,
A power transmission mechanism (30, 50) for connecting the drive shaft 53 of the vehicle and the engine 20 so as to be able to transmit torque and for connecting the drive shaft 53 and the electric motor (second generator motor MG2) so as to be able to transmit torque;
A control device (PM ECU 70, motor ECU 72, engine ECU 73, etc.);
Is provided.

Furthermore, the control device is
When the engine request output Pe * (see step 205 to step 215 in FIG. 2) determined according to the accelerator operation amount AP of the user becomes larger than the engine start threshold value Peonth while the engine 20 is stopped. (See Step 230 and Step 235 in FIG. 2), and when the engine required output Pe * becomes smaller than the engine stop threshold value Peoffth during the operation of the engine 20, the operation of the engine 20 is stopped (see FIG. 2). (See steps 285 and 290). That is, the control device executes intermittent operation of the engine 20. Further, the control device sets the torque equal to the user request torque Tu * (torque required for the drive shaft 53) determined according to the accelerator operation amount AP to “the output torque of the engine 20 and the output of the motor (second generator motor MG2)”. “Torque” is controlled to act on the drive shaft 53 (see Step 240 to Step 265, Step 270, and Step 275 in FIG. 2).

In addition, the control device comprises:
When the engine 20 is stopped, the engine start threshold value Peonth is set so that the engine start threshold value Peonth becomes smaller as the duration time (accelerator pedal ON time Tacon) in which the accelerator operation amount AP is not zero becomes longer (FIG. 2). (See step 225 of FIG. 4 and the table of FIG. 4).

  Accordingly, when the user depresses the accelerator pedal lightly for a short period while the engine is stopped, the engine start threshold value Peonth is set to a large value, and the engine 20 is not started. Therefore, since fuel and electric power are not wasted for starting the engine 20, the fuel efficiency of the hybrid vehicle 10 can be improved. Further, when the user depresses the accelerator pedal greatly while the engine is stopped, and when the accelerator pedal is continuously depressed, the engine 20 is started. As a result, the acceleration performance of the hybrid vehicle 10 can be improved using the output of the engine 20.

Furthermore, the control device comprises:
When the engine 20 is in operation, the engine stop threshold value Peoffth is set so that the engine stop threshold value Peoffth increases as the duration time (engine operation time Tegon) in which the engine 20 is in operation increases (FIG. 2). (See step 280 and the table of FIG. 7).

  Therefore, once the engine 20 is started, the frequency at which the operation of the engine 20 is stopped within a short period of time is reduced, so that the number of times the engine 20 is started can be reduced. As a result, the fuel consumption of the hybrid vehicle 10 can be reduced. Can be improved.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, the power transmission configuration of the hybrid vehicle 10 is not limited to the above embodiment. That is, the present invention can be applied to any hybrid vehicle having a configuration in which the driving force of the hybrid vehicle is generated using an electric motor and an engine and the engine can be intermittently operated.

  DESCRIPTION OF SYMBOLS 10 ... Hybrid vehicle, 20 ... Internal combustion engine, 22 ... Throttle valve, 22a ... Throttle valve actuator, 23 ... Fuel injection valve, 25 ... Crankshaft, 30 ... Power distribution mechanism, 31 ... Planetary gear apparatus, 50 ... Driving force transmission mechanism 53 ... Drive shaft, 83 ... Accelerator operation amount sensor, 85 ... Vehicle speed sensor.

Claims (2)

An internal combustion engine;
An electric motor,
A power transmission mechanism that connects the drive shaft of the vehicle and the engine so as to transmit torque and connects the drive shaft and the electric motor so as to transmit torque;
When the engine demand output determined according to the amount of accelerator operation by the user becomes larger than the engine start threshold value while the engine is stopped, the engine operation is started, and the engine demand output is stopped while the engine is running. A torque equal to a user request torque, which is a torque required for the drive shaft determined according to the user's accelerator operation amount, is executed while performing an intermittent operation to stop the operation of the engine when it becomes smaller than a threshold value. A control device that acts on the drive shaft by controlling the output torque of the motor and the output torque of the motor;
In a hybrid vehicle including
The controller is
When the engine is stopped, the hybrid vehicle is configured to set the engine start threshold value such that the engine start threshold value decreases as the duration of the state in which the accelerator operation amount is not zero is longer. The hybrid vehicle according to claim 1,
The controller is
If the engine is operated, a hybrid vehicle in which the engine is constructed as the duration of the condition being operated to set the aircraft function stop threshold value so that the engine stop threshold longer increases.

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