Hybrid vehicle control device

Abstract

To suppress a torsion angle of a torsion element from varying.SOLUTION: A control device of a hybrid vehicle is used in the hybrid vehicle equipped with an engine and a motor connected to an output shaft of the engine through a torsion element, and controls the motor so that the motor outputs first torque as cranking torque and then the motor outputs second torque lower than the first torque, in making the motor crank the engine to start the vehicle, which controls the motor so that a timing difference between a raising timing for raising the cranking torque toward the first torque and a lowering timing for lowering the cranking torque from the first torque toward the second torque is in a predetermined range including integral multiples of a torsional resonance period of the torsion element.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] Conventionally, as a control device for this type of hybrid vehicle, a device has been proposed that is used in a hybrid vehicle that includes an engine and a motor connected to the output shaft of the engine via a torsion element, and that controls the engine and the motor (see, for example, Patent Document 1). In this hybrid vehicle, when starting the engine, the engine is cranked by the motor to start it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-119405 Summary of the Invention [Problem to be solved by the invention]

[0004] In the hybrid vehicle control device described above, when engine cranking by the motor begins, rate processing is used to increase the cranking torque to rapidly increase the engine speed. From time 1, when the engine speed passes through the resonant speed band or the time required for passing through the resonant speed band has elapsed, rate processing is used to reduce the cranking torque to a torque that allows the engine 22 to stably motor at a predetermined speed or higher. Such changes in cranking torque further increase the fluctuations in the torsion angle of the torsion elements, which in turn increases the rotational fluctuations of the engine's output shaft, potentially increasing vibrations in the drivetrain, including the engine and motor. One possible method for suppressing such vibrations is to perform complex calculations, such as simultaneously solving multiple equations of motion, to calculate a suppression torque to suppress fluctuations in the torsion angle of the torsion elements, and then output the calculated suppression torque from the motor. This method may increase the computational load or may contain errors in the calculated suppression torque, making it impossible to suppress vibrations.

[0005] The main object of the control device for a hybrid vehicle of the present invention is to suppress fluctuations in the torsion angle of the torsion element. [Means for solving the problem]

[0006] The control device for a hybrid vehicle of the present invention employs the following means to achieve the above-mentioned main object.

[0007] The control device for a hybrid vehicle of the present invention comprises: A control device for a hybrid vehicle that is used in a hybrid vehicle including an engine and a motor connected to an output shaft of the engine via a torsion element, and that controls the motor so that, when cranking and starting the engine by the motor, a first torque is output from the motor as a cranking torque and then a second torque lower than the first torque is output from the motor, The motor is controlled so that a timing difference between a rise timing at which the cranking torque is raised toward the first torque and a fall timing at which the cranking torque is lowered from the first torque toward the second torque falls within a predetermined range including an integer multiple of a torsional resonance period of the torsion element. The gist of this is as follows.

[0008] The hybrid vehicle control device of the present invention controls the motor so that the timing difference between the rise timing of the cranking torque toward the first torque and the fall timing of the cranking torque from the first torque to the second torque falls within a predetermined range including an integer multiple of the torsional resonance period of the torsion element. When the cranking torque rises toward the first torque, a fluctuation component with a waveform whose period is the torsional resonance period and whose peak occurs at the rise timing is generated in the torsional angle of the torsion element. When the cranking torque falls from the first torque to the second torque, a fluctuation component with a waveform whose period is the torsional resonance period and whose peak occurs at the fall timing is generated. Therefore, by setting the timing difference between the rise timing and the fall timing within a predetermined range including an integer multiple of the torsional resonance period of the torsion element, the fluctuation component generated at the rise timing can be reduced by the fluctuation component generated at the fall timing. As a result, fluctuations in the torsion angle of the torsion element can be suppressed. Here, the "predetermined range" can be, for example, a time range equivalent to 120° (±60°) in phase, centered on the timing at which the timing difference is an integer multiple.

[0009] In the hybrid vehicle control device of the present invention, the timing of the torque decrease may be corrected based on the rate of increase of the cranking torque toward the first torque. When the cranking torque increases toward the first torque, the torsion angle undergoes a waveform fluctuation whose period is the torsional resonance period and whose amplitude and phase correspond to the rate of increase of the cranking torque toward the first torque. Therefore, by correcting the timing of the torque decrease based on the rate of increase of the cranking torque, fluctuations in the torsion angle of the torsion element can be more appropriately suppressed.

[0010] In this case, the fall timing may be corrected to a timing obtained by adding a first time that is the integral multiple of the torsional resonance period and a second time that is the ratio of the phase delay amount due to the increase rate to 360 degrees multiplied by the torsional resonance period to the rise timing, thereby further suppressing fluctuations in the torsion angle of the torsion element.

[0011] In the hybrid vehicle control device of the present invention, the motor may be controlled to output a torque that is the sum of the cranking torque and a damping torque for suppressing vibrations caused by torque pulsation of the engine, thereby suppressing not only fluctuations in the torsion angle of the torsion element but also fluctuations in the rotation of the output shaft caused by torque pulsation of the engine. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 in which a control device according to an embodiment of the present invention is used. [Figure 2] 10 is an explanatory diagram showing an example of changes over time in cranking torque Tcr, damping torque Tc, and torque command Tm1* of motor MG1. FIG. [Figure 3] 2 is an explanatory diagram for explaining an example of torsion elements of a drive train including an engine 22, motors MG1 and MG2, and a planetary gear 30 of a hybrid vehicle 20. FIG. [Figure 4]10 is an explanatory diagram for explaining AC components and DC components of fluctuations in torsion angle θ. FIG. [Figure 5] FIG. 4 is an explanatory diagram for explaining an example of the relationship between the rate of increase of cranking torque Tcr and torsion angle θ. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, a mode for carrying out the present invention will be described using examples. [Example]

[0014] 1 is a diagram showing an outline of the configuration of a hybrid vehicle 20 in which a control device according to one embodiment of the present invention is used. As shown in the figure, the hybrid vehicle 20 of the embodiment includes an engine 22, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, a boost converter 46, and a hybrid electronic control unit (hereinafter referred to as "HVECU") 70.

[0015] The engine 22 is configured as an internal combustion engine that outputs power using gasoline, diesel, etc. The operation of the engine 22 is controlled by an engine electronic control unit (hereinafter referred to as "engine ECU") 24.

[0016] Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, input / output ports, and communication ports. Signals from various sensors required for controlling the operation of the engine 22, such as a crank angle θcr from a crank position sensor 23 that detects the rotational position of a crankshaft (output shaft) 26 of the engine 22, are input to the engine ECU 24 via an input port. Various control signals for controlling the operation of the engine 22 are output from the engine ECU 24 via an output port. The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotational position and rotation speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor 23.

[0017] The planetary gear 30 is configured as a single-pinion planetary gear mechanism. A rotor of a motor MG1 is connected to a sun gear 31 of the planetary gear 30. A ring gear 32 of the planetary gear 30 is connected to a drive shaft 36 via a gear mechanism 35. The drive shaft 36 is connected to drive wheels 39a, 39b via a differential gear 37 and a drive shaft 38. A crankshaft 26 of the engine 22 is connected to an input shaft 30a via a damper 28, which is connected to a carrier 34 that connects the pinion gears 33 of the planetary gear 30. The gear mechanism 35 has a counter gear 35a that transmits the rotation of the ring gear 32 of the planetary gear 30, a final gear 35b that transmits the rotation of the counter gear 35a to the drive shaft 36, and a reduction gear 35c that reduces the rotation of the rotor of the motor MG2 and transmits it to the final gear 35b.

[0018] The motor MG1 is configured as, for example, a synchronous generator motor, and as described above, its rotor is connected to the sun gear 31 of the planetary gear 30. The inverter 41 is connected to the battery 50 via a boost converter 46. The motor MG2 is configured as, for example, a synchronous generator motor, and its rotor is connected to the drive shaft 36 via the reduction gear 35c and final gear 35b of the gear mechanism 35. The inverter 42 is connected to the battery 50 via the boost converter 46. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as "motor ECU") 40, which controls the switching of multiple switching elements (not shown) of the inverters 41 and 42.

[0019] Although not shown, boost converter 46 is configured as a well-known DC / DC converter including two transistors, two diodes, and a reactor. By motor ECU 40 controlling the switching of two transistors (not shown), boost converter 46 boosts the power on the battery voltage system power line on the battery 50 side and supplies it to the drive voltage system power line on the inverters 41, 42 side, or reduces the power on the drive voltage system power line and supplies it to the battery voltage system power line.

[0020] The motor ECU 40 is configured as a microprocessor centered around a CPU (not shown). In addition to the CPU, it also includes a ROM for storing processing programs, a RAM for temporarily storing data, input / output ports, and communication ports. The MG1 ECU 40 receives signals from various sensors required for driving and controlling the motors MG1 and MG2 via input ports, such as rotational positions θm1 and θm2 from rotational position detection sensors (not shown) that detect the rotational positions of the rotors of the motors MG1 and MG2, and phase currents Iu1, Iv1, Iu2, and Iv2 applied to the motors MG1 and MG2 from current sensors (not shown). The input ports also receive a drive voltage system voltage VH from a voltmeter (not shown) attached to the drive voltage system power line, and a battery voltage system voltage VL from a voltmeter (not shown) attached to the battery voltage system power line. The motor ECU 40 outputs switching control signals to multiple switching elements (not shown) of the inverters 41 and 42, a switching control signal to the boost converter 46, and other signals via output ports. The motor ECU 40 is connected via a communication port to the HVECU 70. The motor ECU 40 calculates the rotation speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotation positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from rotation position detection sensors (not shown).

[0021] The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery. As described above, the battery 50 is connected to the boost converter 46 and the inverters 41, 42 via the system main relay 56. The battery 50 is managed by a battery electronic control unit (hereinafter referred to as "battery ECU") 52.

[0022] Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors required for managing the battery 50 are input to the battery ECU 52 via the input port, such as a battery voltage Vb from a voltage sensor (not shown) installed between the terminals of the battery 50 and a battery current Ib from a current sensor (not shown) attached to the output terminal of the battery 50. The battery ECU 52 is connected to the HVECU 70 via the communication port. The battery ECU 52 calculates a power storage percentage SOC based on an integrated value of the battery current Ib from the current sensor (not shown). The power storage percentage SOC is the ratio of the amount of power that can be discharged from the battery 50 to the total capacity of the battery 50.

[0023] Although not shown, the HVECU 70 is configured as a microprocessor centered around a CPU. In addition to the CPU, the HVECU 70 includes a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory, input / output ports, and communication ports. Signals from various sensors are input to the HVECU 70 via the input ports. Examples of signals input to the HVECU 70 include an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82, an accelerator opening Acc from an accelerator pedal position sensor 84, a brake pedal position BP from a brake pedal position sensor 86, and a vehicle speed V from a vehicle speed sensor 88. Various control signals, such as a drive control signal to the system main relay 56, are output from the HVECU 70 via the output ports. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication ports.

[0024] The hybrid vehicle 20 of the embodiment configured as described above performs hybrid running (HV running) in which the vehicle runs with the engine 22 running, and electric running (EV running) in which the vehicle runs with the engine 22 stopped running.

[0025] Next, the operation of the hybrid vehicle 20 using the control device of the embodiment will be described, particularly the operation of suppressing vibrations during start-up of the engine 22. The engine 22 starts when the required torque Td* and required driving power P* set for the drive shaft 36 based on the accelerator pedal position Acc and the vehicle speed V during EV driving exceed threshold values. Specifically, the engine ECU 24, motor ECU 40, and HVECU 70 cooperate to control the motor MG1 to output a torque equal to the sum of the cranking torque Tcr and the vibration damping torque Tc, thereby cranking the engine 22 and initiating intake air amount control, fuel injection control, and ignition control. At this time, the motor MG2 outputs a torque equal to the sum of the required torque Td* and a cancel torque that cancels the torque output from the motor MG1 to the drive shaft 36.

[0026] 2 is an explanatory diagram showing an example of time variations in cranking torque Tcr, damping torque Tc, and torque command Tm1* of motor MG1. As shown in the figure, immediately after timing (start-up timing) tr when a start command for engine 22 is issued, cranking torque Tcr is set to a relatively large first torque T1 (torque in a direction that increases engine speed Ne) that rapidly increases engine speed Ne of 22 using rate processing. Then, from timing (fall-down timing) tf1 when engine speed Ne of 22 passes through a resonance speed band (e.g., 400 rpm to 600 rpm) or the time required to pass through the resonance speed band has elapsed, cranking torque Tcr is set to a second torque T2 that enables stable motoring of engine 22 at or above a predetermined rotation speed Nstart (e.g., 1000 rpm or 1200 rpm). Furthermore, from timing (fall-down timing) tf2 after engine speed Ne of 22 reaches the predetermined rotation speed Nstart, cranking torque Tcr is set to a value of 0 using rate processing. Thereafter, when it is determined that the engine 22 has completely exploded, the torque is set to a torque for power generation, although this is not shown in the figures. Here, the predetermined rotation speed Nstart is the rotation speed at which fuel injection control and ignition control of the engine 22 are started. The rise timing tr and the fall timings tf1 and tf2 are predetermined timings, and will be described in detail later. The damping torque Tc is set as a torque that cancels out the pulsating torque Tepu, i.e., a torque with the same amplitude and the same period as the pulsating torque Tepu but in the opposite phase.

[0027] In this embodiment, the rise timing tr and the fall timings tf1 and tf2 are set so that the timing difference Δt1 between the rise timing tr and the fall timing tf1 and the timing difference Δt2 (>Δt1) between the rise timing tr and the fall timing tf2 are within a range of 120° (±60°) in phase, centered on the resonance period (torsional resonance period) Tdm of the torsional element of the drivetrain. FIG. 3 is an explanatory diagram illustrating an example of the torsional elements of the drivetrain including the engine 22, motors MG1 and MG2, and planetary gear 30 of a hybrid vehicle 20. As shown in the figure, the hybrid vehicle 20 is equipped with a damper 28, an engine mount, and a driveshaft 38 as torsional elements. When the motor MG1 cranks the crankshaft 26 of the engine 22, the damper 28 twists, causing a fluctuation in the torsional angle θ of the damper 28, and causing vibrations throughout the drivetrain including the engine 22 and motors MG1 and MG2.

[0028] The AC and DC components of the torsion angle θ change with time depending on the cranking torque Tcr. FIG. 4 is an explanatory diagram illustrating the AC and DC components of the torsion angle θ. When the cranking torque Tcr is increased toward the first torque T1, a waveform fluctuation occurs in the torsion angle θ, which has a period equal to the resonance period Tdmp and a valley at the rising timing tr, as shown by the AC component θrac and the DC component θrdc in the diagram. When the cranking torque Tcr is decreased from the first torque T1 toward the second torque T2, a new waveform fluctuation occurs, which has a period equal to the resonance period Tdmp and a peak at the falling timing tf1, as shown by the AC component θf1ac and the DC component θf1dc in the diagram. Since the fluctuation in the torsion angle θ is the sum of the fluctuation component occurring at the rise timing tr and the fluctuation component occurring at the fall timing tf1, if the timing difference Δt1 between the rise timing tr and the fall timing tf1 is set to an integer multiple of the resonance period Tdmp, the fluctuation component occurring at the rise timing tr can be reduced by the fluctuation component occurring at the fall timing tf1, thereby suppressing the fluctuation in the torsion angle θ. As with the timing difference Δt1, if the timing difference Δt2 between the rise timing tr and the fall timing tf2 is set to an integer multiple of the resonance period Tdmp, the fluctuation component occurring at the rise timing tr can be reduced by the fluctuation component occurring at the fall timing tf2 (AC component θf2ac, DC component θf2dc), thereby suppressing the fluctuation in the torsion angle θ.

[0029] Since it is difficult to make the timing differences Δt1 and Δt2 coincide with the resonance period Tdmp of the torsional element of the drivetrain, in this embodiment, the rise timing tr and the fall timings tf1 and tf2 are set so that the timing differences Δt1 and Δt2 are within a range of 120° (±60°) in phase, centered on the resonance period Tdmp of the torsional element of the drivetrain. This makes it possible to suppress fluctuations in the torsional angle θ of the damper 28 and vibrations of the hybrid vehicle 20.

[0030] According to the hybrid vehicle 20 using the control device of the embodiment described above, the motor MG1 is controlled so that the timing difference Δt1 between the rise timing tr and the fall timing tf1 is within a predetermined range including an integer multiple of the resonance period Tdmp of the damper 28, thereby suppressing fluctuations in the torsional angle θ of the damper 28.

[0031] Furthermore, since the motor MG1 is controlled so as to output the sum of the cranking torque Tcr and the damping torque Tc, torque pulsation of the engine 22 can be suppressed.

[0032] In the hybrid vehicle 20 using the control device of the embodiment, the motor MG1 is controlled so that the timing difference Δt1 between the rise timing tr and the fall timing tf1 is within a predetermined range including an integer multiple of the resonance period Tdmp of the damper 28. However, the motor MG1 may also be controlled so that the timing difference Δt1 between the rise timing tr and the fall timing tf1 is an integer multiple of the resonance period Tdmp of the damper 28.

[0033] In a hybrid vehicle 20 using the control device of the embodiment, the timing difference Δt1 between the rise timing tr and the fall timing tf1 is set so that it falls within a predetermined range including an integer multiple of the resonance period Tdmp of the damper 28. However, using the following equation (1), the fall timing tf1 may be set to the rise timing tr plus a time that is an integer multiple of the resonance period Tdmp (=n·Tdmp, where n is an integer equal to or greater than 2, a first time) and a time obtained by multiplying the ratio of the phase delay amount α due to the increase rate of the cranking torque Tcr to 360° by the resonance period Tdmp (=α / 360°·Tdmp, a second time). Figure 5 is an explanatory diagram illustrating an example of the relationship between the increase rate of the cranking torque Tcr and the torsion angle θ. As shown in the figure, when the cranking torque Tcr has a low rate of increase (torque Tcr2), the torsion angle θ fluctuates with a lower amplitude and a slower phase in the same cycle compared to when the cranking torque Tcr rises stepwise (torque Tcr1). Therefore, by determining this phase delay α in advance through experiments, analysis, machine learning, or the like, and setting the fall time taking into account the phase delay α using an equation similar to the following equation (1), fluctuations in the torsion angle θ can be more appropriately suppressed. Furthermore, because a phase delay also occurs when the cranking torque Tcr falls, the fall timing tf1 may be set taking into account this phase delay β using an equation similar to the following equation (2). Furthermore, the fall timing tf2 may also be set taking into account the phase delays α and β, similar to the fall timing tf1.

[0034] tf1=tr+(n+α / 360°)·Tdmp···(1) tf1=tr+(n+(α-β) / 360°)·Tdmp···(2)

[0035] In a hybrid vehicle 20 using the control device of the embodiment, the motor ECU 40 and the HVECU 70 cooperate to control the motor MG1 so that the motor MG1 outputs a torque that is the sum of the cranking torque Tcr and the damping torque Tc. However, the motor MG1 may be controlled by only one of the motor ECU 40 and the HVECU 70.

[0036] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described. In the embodiment, the motor ECU 40 and the HVECU 70 correspond to the "control device for a hybrid vehicle."

[0037] The correspondence between the main elements of the Examples and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the Examples are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the Examples are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0038] The above describes the form for carrying out the present invention using examples, but the present invention is not limited to these examples in any way, and it goes without saying that the present invention can be carried out in various forms within the scope that does not deviate from the gist of the present invention. [Industrial Applicability]

[0039] The present invention can be used in the manufacturing industry of control devices for hybrid vehicles. [Explanation of symbols]

[0040] 20 hybrid vehicle, 22 engine, 23 crank position sensor, 24 engine electronic control unit (engine ECU), 26 crankshaft, 28 damper, 30 planetary gear, 35 gear mechanism, 35a counter gear, 35b final gear, 35c, 37 reduction gear, 36 drive shaft, 38 drive shaft, 39a, 39b drive wheels, 40 motor electronic control unit (motor ECU), 42 inverter, 46 boost converter, 50 battery, 52 battery electronic control unit (battery ECU), 70 hybrid electronic control unit (HVECU), 80 ignition switch, 82 shift position sensor, 84 accelerator pedal position sensor, 86 brake pedal position sensor, 88 vehicle speed sensor, MG1, MG2 motor.

Claims

1. A control device for a hybrid vehicle that is used in a hybrid vehicle including an engine and a motor connected to an output shaft of the engine via a torsion element, the control device controlling the motor so that, when cranking and starting the engine by the motor, a first torque is output from the motor as a cranking torque and then a second torque lower than the first torque is output from the motor, The motor is controlled so that a timing difference between a rise timing at which the cranking torque is raised toward the first torque and a fall timing at which the cranking torque is lowered from the first torque toward the second torque falls within a predetermined range including an integer multiple of a torsional resonance period of the torsion element. Hybrid vehicle control device.

2. 2. The control device for a hybrid vehicle according to claim 1, The timing of the decrease is corrected based on an increase rate when the cranking torque is increased toward the first torque. Hybrid vehicle control device.

3. 3. The control device for a hybrid vehicle according to claim 2, The fall timing is corrected to a timing obtained by adding a first time that is the integral multiple of the torsional resonance period and a second time that is the ratio of the phase delay amount due to the rise rate to 360 degrees multiplied by the torsional resonance period to the rise timing. Hybrid vehicle control device.

4. 2. The control device for a hybrid vehicle according to claim 1, The motor is controlled so that a torque equal to the sum of the cranking torque and a vibration damping torque for suppressing vibrations due to torque pulsation of the engine is output. Hybrid vehicle control device.

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