Control system for hybrid vehicles

Abstract

To provide a control device for a hybrid vehicle, capable of suppressing vehicle vibration from increasing when starting the engine by cranking with an electric motor.SOLUTION: A hybrid vehicle 10 includes: an engine 12; a first electric motor MG1 connected to the engine 12 so as to be able to transmit power; and a damper 22 that absorbs vibrations during power transmission between the engine 12 and the first electric motor MG1. When starting the engine 12 by cranking using the first electric motor MG1, an electronic control device 90 sets an output waveform of first electric motor torque Tmg1 on the basis of an initial crank angle φinit so that an absolute value of damper differential rotation ΔNd is equal to or less than a predetermined differential rotation determination value ΔNd_jdg.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle including an engine, an electric motor connected to the engine so as to be able to transmit power thereto, and a damper that absorbs vibrations of power transmission between the engine and the electric motor.

Background Art

[0002] A control device for a hybrid vehicle including an engine, an electric motor connected to the engine so as to be able to transmit power thereto, and a damper that absorbs vibrations of power transmission between the engine and the electric motor is known. For example, the one described in Patent Document 1 is such a device. In the control device for a hybrid vehicle described in Patent Document 1, when starting the engine by cranking with the electric motor, the electric motor torque increases or decreases by a predetermined amount that can suppress the excitation of torsional vibration targeted by the electric motor torque for a predetermined period that coincides with the period of torsional vibration generated anywhere on the power transmission path from the damper to a pair of drive wheels.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the control device for a hybrid vehicle described in Patent Document 1, the pulsation of the engine generated by cranking is transmitted to the damper. For example, when the timing of the return swing of the damper twisted by the electric motor torque overlaps with the timing of this engine pulsation, the differential rotation in the damper may instantaneously increase. In this case, there is a risk that the vehicle vibration generated when the torsion accumulated in the damper is released deteriorates.

[0005] The present invention was made against the above circumstances, and its objective is to provide a control device for a hybrid vehicle that can suppress the deterioration of vehicle vibration when the engine is started by cranking with an electric motor. [Means for solving the problem]

[0006] The gist of this invention is (a) A control device for a hybrid vehicle comprising an engine, an electric motor connected to the engine so as to transmit power, and a damper for absorbing vibrations of power transmission between the engine and the electric motor, (b) When the motor is cranked to start the engine, the output waveform of the motor torque output from the motor is set based on the crank angle at the start of engine startup, so that the absolute value of the difference in rotation at the damper is less than or equal to a predetermined difference in rotation determination value. (c) The differential rotation in the damper includes a first differential rotation component in the damper caused by the pulsation of the engine due to the cranking, and a second differential rotation component in the damper caused by the rebound of the damper twisted by the electric motor torque, and (d) when starting the engine, a first timing in which the absolute value of the first differential rotation component is first maximized and a second timing in which the second differential rotation component is maximized with the same polarity as the first differential rotation component at the first timing, which is closest to the first timing, are separated by a predetermined period of time or longer. It is the matter. [Effects of the Invention]

[0007] According to the control device for a hybrid vehicle of the present invention, when the electric motor cranks and the engine is started, the output waveform of the electric motor torque output from the electric motor is set based on the crank angle at the start of engine startup so that the absolute value of the differential rotation at the damper is less than or equal to a predetermined differential rotation determination value. The timing of the fluctuation of the differential rotation at the damper changes according to the crank angle at the start of engine startup. Therefore, by setting the output waveform of the electric motor torque based on the crank angle at the start of engine startup, it is possible to control the absolute value of the differential rotation at the damper so that it is less than or equal to a predetermined differential rotation determination value. The amount of torsion of the damper changes according to the time integral value of the differential rotation at the damper, so the amount of torsion of the damper is also suppressed when the differential rotation at the damper is suppressed. This suppresses the deterioration of vehicle vibration that occurs when the torsion accumulated in the damper is released. Furthermore, the differential rotation at the damper includes a first differential rotation component at the damper caused by engine pulsation due to cranking, and a second differential rotation component at the damper caused by the rebound of the damper twisted by the electric motor torque. When the engine is started, the first timing, in which the absolute value of the first differential rotation component is initially at its maximum, and the second timing, which is the closest to the first timing among the timings in which the second differential rotation component is at its maximum with the same negative polarity as the first differential rotation component at the first timing, are separated by a predetermined period of time or more. The amount of fluctuation in the second differential rotation component is larger in the period immediately after the start of the fluctuation compared to the period afterward. By separating the first and second timings by a predetermined period of time or more, the instantaneous increase in differential rotation at the damper during the period when the amount of fluctuation is relatively large immediately after the start of the fluctuation of the second differential rotation component is suppressed. This suppresses the deterioration of vehicle vibration that occurs when the torsion accumulated in the damper is released. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram shows a schematic configuration of a hybrid vehicle equipped with an electronic control device according to an embodiment of the present invention, as well as a functional block diagram representing the main parts of the control functions for various controls in the vehicle. [Figure 2] This is an example of a time chart illustrating the changes in the crank angle and engine pulsation torque waveforms after engine startup, caused by differences in the crank angle at the start of engine startup, as per the reference example. [Figure 3] This is an example of a time chart that provides an overview of the differential rotation component in the damper caused by the rebound of the damper twisted by the torque of the first electric motor, the differential rotation component in the damper caused by the engine pulsation torque, and the damper differential rotation, which is the overall differential rotation in the damper, as per the reference example. [Figure 4] This is an example of a time chart illustrating the changes in the waveforms of the crank angle and engine pulsation torque after engine startup, according to this embodiment. [Figure 5] This is an example of a time chart illustrating the general characteristics of the differential rotation component in the damper caused by the rebound of the damper twisted by the torque of the first electric motor, the differential rotation component in the damper caused by the engine pulsation torque, and the damper differential rotation, which is the overall differential rotation in the damper, in this embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0010] Figure 1 is a schematic diagram of a hybrid vehicle 10 (hereinafter simply referred to as "vehicle 10") equipped with an electronic control device 90 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of the control functions for various controls in vehicle 10. Vehicle 10 is a hybrid vehicle equipped with, for example, an engine 12 and a second electric motor MG2 as a power source for driving. In the power transmission path PT between the engine 12 and a pair of drive wheels 14, vehicle 10 is equipped with, in order from the engine 12 side, a crankshaft 20, a damper 22, an input shaft 24, a power split mechanism 26, an output shaft 28, a differential 30, and a pair of axles 32, which are well known configurations. In addition, vehicle 10 is equipped with an inverter 50, a battery 52, and an electronic control device 90.

[0011] The engine 12 is a well-known internal combustion engine, and its output torque, engine torque Te [Nm], is controlled by the electronic control unit 90. In this specification, unless otherwise specified, driving force, power, force (=power), and torque are synonymous. The first motor MG1 and the second motor MG2 are so-called motor generators, for example, three-phase synchronous motor generators. The output torque of the first motor MG1, first motor torque Tmg1 [Nm], and the output torque of the second motor MG2, second motor torque Tmg2 [Nm], are controlled by the inverter 50 controlled by the electronic control unit 90, respectively.

[0012] The power split mechanism 26 is composed of, for example, a known single-pinion type planetary gear system. The sun gear S0, carrier CA0, and ring gear R0 of the planetary gear system constituting the power split mechanism 26 are connected to the engine 12 and the output shaft 28, respectively, via the first electric motor MG1, the input shaft 24, and the damper 22. The power split mechanism 26 is a well-known power split mechanism that mechanically divides the power output from the engine 12 to the first electric motor MG1 and the output shaft 28. The first electric motor MG1 is connected to the engine 12 in a power-transmitting manner. The second electric motor MG2 is connected to the power transmission path PT between the engine 12 and a pair of drive wheels 14 in a power-transmitting manner. The first electric motor MG1 corresponds to the "electric motor" in this invention.

[0013] The inverter 50 converts DC to AC and AC to DC. The inverter 50 performs power conversion between the first motor MG1 and the battery 52, and between the second motor MG2 and the battery 52.

[0014] Battery 52 is a secondary battery that supplies power to and from the first motor MG1 and the second motor MG2, and is a battery for driving the first motor MG1 and the second motor MG2.

[0015] The electronic control unit 90 includes, for example, a so-called microcomputer, and performs signal processing according to a program pre-stored in ROM to control various parts of the vehicle 10. The electronic control unit 90 corresponds to the "control device" in this invention.

[0016] The electronic control unit 90 receives various signals based on detection values ​​from various sensors installed in the vehicle 10 (engine rotation speed sensor 70, first motor rotation speed sensor 72, second motor rotation speed sensor 74, vehicle speed sensor 76, accelerator pedal position sensor 78, battery sensor 80, pressure sensor 82, etc.), such as engine rotation speed Ne [rpm], crank angle φcrk [deg], which represents the rotational position of the crankshaft 20, first motor rotation speed Nmg1 [rpm], which represents the rotation speed of the first motor MG1, second motor rotation speed Nmg2 [rpm], which represents the rotation speed of the second motor MG2, vehicle speed V [km / h], accelerator pedal position θacc [%], which represents the magnitude of acceleration operation by the driver, battery charge state value SOC [%], and internal pressure Pe [Pa] in the cylinder of the engine 12. The engine rotation speed sensor 70 is a resolver that can detect, for example, the engine rotation speed Ne and the crank angle φcrk. The charge state value (SOC) is the ratio of the actual amount of charge stored to the fully charged capacity of the battery 52, which is predetermined.

[0017] From the electronic control device 90, various command signals (engine control signal Se, first motor control signal Smg1 for rotationally controlling the first motor MG1 and the second motor MG2 via the inverter 50, second motor control signal Smg2, etc.) are output to each device (engine 12, inverter 50, etc.) of the vehicle 10, respectively.

[0018] In the vehicle 10, for example, a BEV (Battery Electric Vehicle) driving mode in which only the second motor MG2 among the driving power sources outputs power and the vehicle travels, and an engine driving mode in which at least the engine 12 among the driving power sources outputs power and the vehicle travels are selectable. The switching from the BEV driving mode to the engine driving mode is performed, for example, when the first motor torque (= cranking torque) Tmg1 output from the first motor MG1 during BEV driving is transmitted to the engine 12 via the damper 22, and thereby the engine 12 is started and switched from the stopped state to the operating state.

[0019] The damper 22 is a device that absorbs torque fluctuations generated between the engine 12 and the power split mechanism 26 (for example, the first motor MG1). The damper 22 has, for example, a well-known configuration in which a first rotating member connected to the crankshaft 20 on the engine 12 side, a second rotating member connected to the input shaft 24 on the power split mechanism 26 side, and a spring are provided between the circumferential directions of the first rotating member and the second rotating member. When the first rotating member and the second rotating member rotate relative to each other, the spring contracts to absorb the torque fluctuation.

[0020] Hereinafter, the case where the engine 12 is started by being cranked by the first motor MG1 will be described.

[0021] Figure 2 is an example of a time chart illustrating the changes in the waveforms of the crank angle φcrk and engine pulsating torque Tpls [Nm] after engine startup, due to differences in the crank angle φcrk at the start of engine startup ts, in a reference example. The horizontal axis of Figure 2 represents time t [s]. Here, the direction of rotation in which the engine 12 rotates after starting is referred to as the "engine rotation direction".

[0022] The engine start start time ts is synonymous with the start time of cranking by the first electric motor MG1, and corresponds to the "engine start start time" in this invention. The engine pulsating torque Tpls is the pulsating component of the torque that rotates the damper 22 when the engine 12 is being rotated by cranking before engine ignition, and the pulsating component of the torque that rotates the damper 22 when the engine 12 is running after engine ignition. When the engine 12 is rotated, the internal pressure Pe inside the cylinder of the engine 12 is changed as the air inside the cylinder is compressed or expanded. As a result of the change in the internal pressure Pe inside the cylinder of the engine 12, the moment of inertia around the crankshaft 20 changes according to the crank angle φcrk. That is, the moment of inertia around the crankshaft 20 differs according to the crank angle φcrk. Therefore, fluctuations (=pulsation) occur in the torque that the engine 12 rotates the damper 22 according to the crank angle φcrk.

[0023] In the example, the output waveform of the first motor torque Tmg1 for cranking is set as shown by the solid line. In Figure 2 (and similarly in Figure 4 described later), the first motor torque Tmg1, engine rotational speed Ne, and engine pulsation torque Tpls are positive values ​​on the side moving in the direction of engine rotation.

[0024] For example, the first motor torque Tmg1 for cranking is output with the output waveform shown in Figure 2. This increases the engine rotational speed Ne. Here, the crank angle φcrk at the start of engine startup ts is referred to as the "initial crank angle φinit". For example, if the initial crank angle φinit is an angle value of φ1, the crank angle φcrk and engine pulsation torque Tpls change as shown by the solid line, and if the initial crank angle φinit is an angle value of φ2, the crank angle φcrk and engine pulsation torque Tpls change as shown by the dashed line. In other words, the waveforms of the crank angle φcrk and engine pulsation torque Tpls after engine startup change depending on the initial crank angle φinit, and in particular, the points in time when the amount of change is maximum and minimum change. The first motor torque Tmg1 corresponds to the "motor torque" in this invention. The engine pulsation torque Tpls can be detected, for example, based on the internal pressure Pe in the cylinder of the engine 12.

[0025] Figure 3 is an example of a time chart illustrating the general characteristics of the differential rotation component ΔNd_mg1 in the damper 22 caused by the rebound of the damper 22 twisted by the first motor torque Tmg1, the differential rotation component ΔNd_eng in the damper 22 caused by the engine pulsation torque Tpls, i.e., the pulsation of the engine 12, and the damper differential rotation ΔNd, which is the overall differential rotation in the damper 22, in a reference example. The horizontal axis of Figure 3 is time t [s].

[0026] The damper differential rotation ΔNd is the differential rotation at damper 22 (= "rotational speed of the first rotating member" - "rotational speed of the second rotating member"). The damper differential rotation ΔNd includes the differential rotation component ΔNd_eng and the differential rotation component ΔNd_mg1 as its components. The "differential rotation component ΔNd_mg1" and the "differential rotation component ΔNd_eng" can also be said to be the components that generate the "damper differential rotation ΔNd". As shown in Figure 3 (and similarly in Figure 5 described later), the differential rotation component ΔNd_eng[rpm], differential rotation component ΔNd_mg1[rpm], and damper differential rotation ΔNd[rpm] are positive values ​​when the rotational speed of the first rotating member connected to the crankshaft 20 at damper 22 is greater than the rotational speed of the second rotating member connected to the input shaft 24.

[0027] Incidentally, the time integral of the damper difference rotation ΔNd represents the amount of torsion of the damper 22. Since the damper difference rotation ΔNd changes periodically between positive and negative values, suppressing the fluctuation amount of the damper difference rotation ΔNd is equivalent to suppressing the amount of torsion of the damper 22.

[0028] In the following, to facilitate understanding of the invention, the damper differential rotation ΔNd will be simplified and explained as a superposition of the differential rotation component ΔNd_eng and the differential rotation component ΔNd_mg1.

[0029] For example, at the start of engine startup ts, the output of the first motor torque Tmg1 for cranking begins. This causes a torsion in the damper 22 due to the first motor torque Tmg1, and a rebound oscillation occurs in the damper 22 due to the spring of the damper 22 in response to this torsion. For example, the differential rotation component ΔNd_mg1 has a waveform as shown in Figure 3. The differential rotation component ΔNd_mg1 has a large amount of fluctuation (= the difference between the maximum and minimum values) immediately after the start of its fluctuation, but it gradually attenuates due to the absorption of the fluctuation by the spring of the damper 22.

[0030] When the first motor torque Tmg1 is transmitted to the engine 12 via the damper 22, the engine 12 begins to rotate while pulsating. This causes torsion in the damper 22 due to the engine pulsation torque Tpls. For example, the differential rotation component ΔNd_eng has a waveform as shown in Figure 3. The differential rotation component ΔNd_eng's fluctuation period gradually shortens as the engine rotation speed Ne increases from immediately after the start of its fluctuation, but the amount of fluctuation does not change substantially. The damper differential rotation ΔNd is formed by the superposition of the differential rotation component ΔNd_mg1 and the differential rotation component ΔNd_eng, resulting in a waveform as shown in Figure 3. Note that the differential rotation component ΔNd_eng and the differential rotation component ΔNd_mg1 correspond to the "first differential rotation component" and the "second differential rotation component" in this invention, respectively.

[0031] As shown in Figure 3, in the example, the time x1 at which the absolute value of the differential rotation component ΔNd_eng is first maximized and the time x2 closest to time x1 at which the differential rotation component ΔNd_mg1 is minimized are the same time. At time x1, the absolute value of the differential rotation component ΔNd_eng is first maximized, and the polarity of the differential rotation component ΔNd_eng is negative. Time x2 is the closest to time x1 at which the differential rotation component ΔNd_mg1 is maximized in the negative polarity (=minimum in the positive polarity). As mentioned above, the fluctuation period of the differential rotation component ΔNd_eng gradually shortens in accordance with the increase in engine rotational speed Ne from immediately after the start of its fluctuation, but the amount of fluctuation does not substantially change. When we say that the absolute value of the differential rotation component ΔNd_eng at time x1 is "first maximized", we mean that it is "first maximized" in the differential rotation component ΔNd_eng that is fluctuating without the amount of fluctuation substantially changing.

[0032] Thus, at time x1 (=x2), the trough in the change of the differential rotation component ΔNd_mg1 and the trough in the change of the differential rotation component ΔNd_eng overlap. Therefore, at time x1 (=x2), the absolute value of the fluctuation amount of damper differential rotation ΔNd, which is the superposition of differential rotation component ΔNd_mg1 and differential rotation component ΔNd_eng, is at its maximum. More precisely, when damper differential rotation ΔNd changes, the differential rotation component ΔNd_mg1 of the damper 22 generated by the twisting of the damper 22 due to the first motor torque Tmg1 and the rebound by the spring changes, and the cranking torque transmitted to the engine 12 via the damper 22 changes, so the differential rotation component ΔNd_eng of the damper 22 generated by the twisting due to the engine pulsation torque Tpls also changes. Therefore, in reality, the fluctuation of damper differential rotation ΔNd after the start of the fluctuation of differential rotation component ΔNd_eng is more complex than described above.

[0033] Returning to Figure 1, the electronic control unit 90 functionally includes a drive control unit 92, a start determination unit 94, an initial crank angle acquisition unit 96, and a target motor torque setting unit 98. The drive control unit 92 functionally includes an engine control unit 92a and a motor control unit 92b.

[0034] The start determination unit 94 determines whether or not it is necessary to start the engine 12. For example, in BEV driving mode, if the required drive torque Trdem increases beyond the range that can be covered by the second motor torque Tmg2 alone, if the engine 12 or the like needs to be warmed up, or if the charge state value (SOC) of the battery 52 falls below a predetermined engine start threshold, it is determined that the engine 12 needs to be started. The engine start threshold is a predetermined threshold used to determine whether the charge state value (SOC) is such that the engine 12 needs to be automatically started to charge the battery 52.

[0035] When the start determination unit 94 determines that the engine 12 needs to be started, the initial crank angle acquisition unit 96 acquires the initial crank angle φinit, which represents the rotational position of the crankshaft 20 at that time. The initial crank angle φinit is acquired based on the crank angle φcrk detected by the engine rotation speed sensor 70.

[0036] When the initial crank angle acquisition unit 96 acquires the initial crank angle φinit, the target motor torque setting unit 98 sets the output waveform of the first motor torque Tmg1 during cranking. For example, the output waveform of the first motor torque Tmg1 is set based on a predetermined map in which the relationship between the initial crank angle φinit and the output waveform of the first motor torque Tmg1 is experimentally or design-driven, so that the damper difference rotation ΔNd generated by cranking is within a predetermined allowable range.

[0037] Figure 4 is an example of a time chart illustrating the changes in the waveforms of the crank angle φcrk and engine pulsation torque Tpls after engine start-up in this embodiment. The horizontal axis of Figure 4 represents time t [s]. In this embodiment, the initial crank angle φinit is the same as in the reference example, with an angle value of φ1, and the output waveform of the first motor torque Tmg1 for cranking is set as shown by the dashed line. For comparison, the waveform in the aforementioned reference example is also shown as a solid line in Figure 4.

[0038] Compared to the output waveform of the first motor torque Tmg1 in the reference example, the output waveform of the first motor torque Tmg1 in this embodiment has a lower rate of increase αmg1 [Nm / s] of the output waveform of the first motor torque Tmg1 immediately after the start of output, and the point at which the first motor torque Tmg1 reaches its maximum value is also delayed. That is, the rate of increase αmg1 of the output waveform of the first motor torque Tmg1 is lower during the period from the start of engine startup ts to time t1. The period from the start of engine startup ts to time t1 includes the period from the start of engine startup ts to the start of the change in the differential rotation component ΔNd_eng y0 (see Figure 5). As a result of this change in the output waveform of the first motor torque Tmg1, the rate of increase of the engine rotational speed Ne is slowed down, the start of the change in the crank angle φcrk is delayed, and the start of the change in the waveform of the engine pulsating torque Tpls is delayed.

[0039] Figure 5 is an example of a time chart illustrating the general characteristics of the differential rotation component ΔNd_mg1 in the damper 22 caused by the rebound of the damper 22 twisted by the first motor torque Tmg1, the differential rotation component ΔNd_eng in the damper 22 caused by the engine pulsation torque Tpls, and the damper differential rotation ΔNd, which is the overall differential rotation in the damper 22, according to this embodiment. The horizontal axis of Figure 5 is time t [s]. In Figure 5, as in Figure 4, the waveform of this embodiment is shown by a dashed line, and the waveform of the reference example is shown by a solid line.

[0040] The rate of increase αmg1 of the output waveform of the first motor torque Tmg1 immediately after the start of output of the first motor torque Tmg1 is lowered, which delays the start of change in the differential rotation component ΔNd_mg1. As a result, the timing at which the differential rotation component ΔNd_mg1 is at its maximum and minimum changes. The delay in the start of change in the waveform of the engine pulsation torque Tpls delays the start of change in the differential rotation component ΔNd_eng. As a result, the timing at which the differential rotation component ΔNd_eng is at its maximum and minimum changes.

[0041] As shown in Figure 5, in this embodiment, the time point y1 at which the absolute value of the differential rotation component ΔNd_eng is first maximized and the time point y2 closest to time point y1 at which the differential rotation component ΔNd_mg1 is minimized are different time points. At time point y1, the absolute value of the differential rotation component ΔNd_eng is first maximized, and the polarity of the differential rotation component ΔNd_eng is negative. Time point y2 is the closest to time point y1 at which the differential rotation component ΔNd_mg1 is maximized in the negative polarity (=minimum in the positive polarity). Note that time points y1 and y2 correspond to the "first timing" and "second timing" in the present invention, respectively. Time points y1 and y2 are separated by a time difference ΔT[s]. That is, at time point y1, the trough in the change of the differential rotation component ΔNd_mg1 and the trough in the change of the differential rotation component ΔNd_eng do not overlap, and their respective troughs are offset. If the period between the time points in the vicinity of time point y1 at which the differential rotation component ΔNd_mg1 is minimized is defined as period Ta[s], then ΔT / Ta is set to be within a predetermined ratio range including "0.5". In other words, the time difference ΔT is set to be separated from period Ta by a time difference determination value ΔT_jdg. The "time difference determination value ΔT_jdg" is a determination value that is experimentally or design-wise predetermined so that the discomfort felt by the driver due to the vibration generated by the torsion of the damper 22 is within a predetermined allowable range. The time difference determination value ΔT_jdg is a value that is greater than zero and less than or equal to half the period Ta (=Ta × 0.5). Note that the time difference determination value ΔT_jdg corresponds to the "predetermined period" in this invention.

[0042] As shown in Figure 5, in the reference example, the damper differential rotation ΔNd at time x1 is the differential rotation value ΔNd1, while in this embodiment, the damper differential rotation ΔNd at time y1 is the differential rotation value ΔNd2 (<ΔNd1). If time x1 and time x2 are the same time, as in the reference example, at time x1 (=x2), the damper differential rotation ΔNd exceeds the differential rotation judgment value ΔNd_jdg, and the discomfort felt by the driver falls outside the predetermined tolerance range. The "differential rotation judgment value ΔNd_jdg" is a predetermined judgment value that is experimentally or design-wise determined in advance, which is the value at which the discomfort felt by the driver falls within the predetermined tolerance range. As in this embodiment, when the time difference ΔT between time point y1 and time point y2 is greater than or equal to the time difference determination value ΔT_jdg, the damper differential rotation ΔNd at time point y1 becomes less than or equal to the differential rotation determination value ΔNd_jdg. Furthermore, even after time point y1, the differential rotation component ΔNd_mg1 gradually attenuates, so the damper differential rotation ΔNd remains less than or equal to the differential rotation determination value ΔNd_jdg. As a result, the discomfort felt by the driver due to vibrations generated by the torsion of the damper 22 falls within a predetermined allowable range.

[0043] According to this embodiment, when the engine 12 is started by cranking with the first electric motor MG1, the output waveform of the first electric motor torque Tmg1 is set based on the initial crank angle φinit so that the absolute value of the damper differential rotation ΔNd is less than or equal to a predetermined differential rotation determination value ΔNd_jdg. The timing of the fluctuation of the damper differential rotation ΔNd changes according to the initial crank angle φinit. Therefore, by setting the output waveform of the first electric motor torque Tmg1 based on the initial crank angle φinit, the absolute value of the damper differential rotation ΔNd can be controlled to be less than or equal to a predetermined differential rotation determination value ΔNd_jdg. Since the amount of torsion of the damper 22 changes according to the time integral value of the damper differential rotation ΔNd, the amount of torsion of the damper 22 is also suppressed when the damper differential rotation ΔNd is suppressed. This suppresses the deterioration of vehicle vibration that occurs when the torsion accumulated in the damper 22 is released.

[0044] According to this embodiment, (a) the damper differential rotation ΔNd includes a differential rotation component ΔNd_eng and a differential rotation component ΔNd_mg1, and (b) when the engine 12 is started, the time y1 at which the absolute value of the differential rotation component ΔNd_eng is first maximized and the time y2 closest to time y1 among the times at which the differential rotation component ΔNd_mg1 is maximized in the same negative polarity as the differential rotation component ΔNd_eng at time y1 are separated by a time difference determination value ΔT_jdg or more. The amount of fluctuation of the differential rotation component ΔNd_mg1 is larger in the period immediately after the start of the fluctuation compared to the period afterward. By separating time y1 and time y2 by a time difference determination value ΔT_jdg or more, the instantaneous increase in the damper differential rotation ΔNd during the period when the amount of fluctuation of the differential rotation component ΔNd_mg1 is relatively large immediately after the start of the fluctuation is suppressed. As a result, the deterioration of vehicle vibration that occurs when the torsion accumulated in the damper 22 is released is suppressed.

[0045] According to this embodiment, the output waveform of the first motor torque Tmg1 is set to have a low rise rate αmg1 for the period from the start of engine startup ts to time t1 (= including the period from the start of engine startup ts to the start of the change in the differential rotation component ΔNd_eng y0), based on the initial crank angle φinit. By lowering the rise rate αmg1 for the period from the start of engine startup ts to the start of the change in the differential rotation component ΔNd_eng y0, the start of the change in the differential rotation component ΔNd_mg1 is delayed, and the start of the change in the waveform of the engine pulsation torque Tpls is also delayed. As a result, time y2 and time y1 are separated by a time difference determination value ΔT_jdg or more, which suppresses an increase in the damper differential rotation ΔNd and suppresses the deterioration of vehicle vibration.

[0046] According to this embodiment, the output waveform of the first motor torque Tmg1 is set to have a low rise rate αmg1 at the engine start time ts, based on the initial crank angle φinit. As a result, the time difference between time point y2 and time point y1 is set to be greater than or equal to the time difference determination value ΔT_jdg, which suppresses an increase in the damper difference rotation ΔNd and suppresses the deterioration of vehicle vibration.

[0047] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit.

[0048] In the embodiments described above, a configuration in which the initial crank angle φinit is an angle value φ1 was explained, but the present invention is not limited to this configuration. In configurations in which the initial crank angle φinit is an angle value other than φ1, the output waveform of the first motor torque Tmg1 should be set based on the initial crank angle φinit such that the absolute value of the damper differential rotation ΔNd is less than or equal to the differential rotation determination value ΔNd_jdg.

[0049] In the above-described embodiment, the time difference determination value ΔT_jdg or more was set to separate the time point y1, when the absolute value of the differential rotation component ΔNd_eng is first maximum, and the time point y2, when the differential rotation component ΔNd_mg1 is minimum. However, the present invention is not limited to this embodiment. For example, the time difference determination value ΔT_jdg or more may be set to separate the time point when the absolute value of the differential rotation component ΔNd_eng is maximum for the second time from the time point when the differential rotation component ΔNd_mg1 is maximum. Since the period Ta does not change substantially near time point y1, the same effect as in the above-described embodiment can be achieved even if the time point when the absolute value of the differential rotation component ΔNd_eng is maximum for the second time is targeted.

[0050] In the above-described embodiment, the rate of increase αmg1 of the output waveform of the first motor torque Tmg1 during the period from the start of engine startup ts to the start of fluctuation of the differential rotation component ΔNd_eng y0 was set to be low based on the initial crank angle φinit. However, the present invention is not limited to this embodiment. For example, the rate of increase αmg1 of the output waveform of the first motor torque Tmg1 at any point during the period from the start of engine startup ts to the start of fluctuation of the differential rotation component ΔNd_eng y0 may be low based on the initial crank angle φinit. In such an embodiment, the rate of increase of the engine rotation speed Ne is slowed down, which delays the start of the change in the crank angle φcrk or the start of the change in the waveform of the engine pulsating torque Tpls.

[0051] In the above-described embodiment, in order to suppress an increase in the damper differential rotation ΔNd, the rate of rise αmg1 of the output waveform of the first motor torque Tmg1 at the start of engine startup ts was set to be low. However, the present invention is not limited to this embodiment. For example, in order to suppress an increase in the damper differential rotation ΔNd, the rate of rise αmg1 of the output waveform of the first motor torque Tmg1 during the period from the start of engine startup ts to time t1 (= including the period from the start of engine startup ts to the start of fluctuation y0 of the differential rotation component ΔNd_eng) may be set to be high. Thus, the present invention may also be an embodiment in which the rate of rise αmg1 of the output waveform of the first motor torque Tmg1 at the start of engine startup ts is increased or decreased based on the initial crank angle φinit in order to suppress an increase in the damper differential rotation ΔNd. That is, in order to suppress an increase in the damper differential rotation ΔNd, the rate of rise αmg1 of the output waveform of the first motor torque Tmg1 at the start of engine startup ts may be set to different values ​​based on the initial crank angle φinit. [Explanation of Symbols]

[0052] 10: Hybrid vehicle, 12: Engine, 22: Damper, 90: Electronic control unit (control unit), MG1: First motor (motor), Tmg1: First motor torque (motor torque), ts: Engine start start time (engine start start time), y0: Fluctuation start time, y1: Time (first timing), y2: Time (second timing), αmg1: Increase rate, ΔNd: Damper differential rotation (difference rotation at the damper), ΔNd_eng: Differential rotation component (first differential rotation component), ΔNd_jdg: Differential rotation judgment value (predetermined differential rotation judgment value), ΔNd_mg1: Differential rotation component (second differential rotation component), ΔT_jdg: Time difference judgment value (predetermined period), φcrk: Crank angle

Claims

1. A control device for a hybrid vehicle comprising an engine, an electric motor connected to the engine so as to transmit power, and a damper for absorbing vibrations of power transmission between the engine and the electric motor, When the motor is cranked to start the engine, the output waveform of the motor torque output from the motor is set based on the crank angle at the start of engine startup so that the absolute value of the difference in rotation at the damper is less than or equal to a predetermined difference in rotation determination value. The differential rotation in the damper includes a first differential rotation component in the damper caused by the pulsation of the engine due to the cranking, and a second differential rotation component in the damper caused by the rebound of the damper twisted by the electric motor torque. When starting the engine, the first timing at which the absolute value of the first differential rotation component is initially at its maximum, and the second timing, which is the closest to the first timing among the timings at which the second differential rotation component is at its maximum with the same polarity as the first differential rotation component at the first timing, are separated by a predetermined period of time or more. A control device for a hybrid vehicle characterized by the following features.

2. The output waveform of the motor torque is set such that, based on the crank angle at the start of engine startup, the rate of increase of the output waveform of the motor torque at any point in the period from the start of engine startup to the start of fluctuation of the first differential rotation component is different. A control device for a hybrid vehicle according to feature 1.

3. The output waveform of the motor torque is set to have a different rate of increase at the time the engine starts, based on the crank angle at the start of engine startup. The control device for a hybrid vehicle according to feature 2.

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