Vehicle control device

Abstract

Control device (80; 102; 222) for a vehicle (10; 100; 200) equipped with a motor (12; 202) and an electric motor (MG1; MG) which adjusts a torque to be transmitted to the drive wheels (40; 216), wherein the control device comprises: a control section (84; 106) configured to control the electric motor (MG1; MG) to generate a limiting torque (Tcon) for a drive wheel torque to limit a torque to be applied to the drive wheels (40; 216) at the initial explosion of the motor (12; 202) as a result of cranking the motor to start the motor, when a predetermined length of delay time (tset1; tset2; tset) has elapsed after a predetermined time before a moment of the initial explosion of the motor, and a time setting section (86; 108) configured to set the predetermined length of the delay time based on an operating speed (Ne) of the engine during engine cranking and one of the elements, pre-start crank angle (Acr) of the engine at rest and rate of rise (ΔNe) of the operating speed of the engine during cranking, characterized by the fact that the predetermined time is a moment (t2) of the generation of a control instruction to initiate a fuel injection into the engine (12; 202) or a time (ta) at which a predetermined time (tf) has elapsed after the moment of the generation of the control instruction, and the time setting section (108) sets the length of the delay time (tset2) based on the operating speed (Nex) of the motor at the moment the control instruction is generated and the rate of increase (ΔNex) of the operating speed of the motor during a time period in the process of cranking the motor, where the time period begins at the moment the control instruction is generated and has a length of the predetermined time (tf).

Description

FIELD OF INVENTION

[0001] The present invention relates to a control system for a vehicle to reduce vibration following a first or initial explosion of its engine. BACKGROUND OF THE INVENTION

[0002] In the field of a vehicle equipped with an internal combustion engine and an electric motor, it has been proposed to control the electric motor to generate a limiting torque for a drive wheel torque. This limiting torque is intended to be transmitted to the vehicle's drive wheels after an initial combustion of the internal combustion engine, resulting from cranking the engine, in order to start the internal combustion engine. Patent document 1, identified below, discloses an example of a method for this control of the electric motor.This publication describes the generation of the limiting torque of the drive wheel torque by the electric motor at a time when a predetermined length of delay time has elapsed after a predetermined time before the moment of the initial explosion of the internal combustion engine, namely after the moment of generating an instruction to start the internal combustion engine (a moment of initiating a fuel injection and combustion control of the internal combustion engine), and also describes an adjustment of the length of the delay time based on a difference between a crank angle of the internal combustion engine at rest and a target value of the crank angle in order to synchronize the moment of the initial explosion with the moment of generation of the limiting torque of the drive wheel torque by the electric motor. State-of-the-art documentation Patent document 1: JP 2009- 161 142 A Patent document 2: JP 2008- 155 741 A Patent document 3: JP 2009- 184 367 A Patent document 4: US 2009 / 0 256 513 A1 SUMMARY OF THE INVENTION

[0003] Furthermore, the rate of increase of the operating speed or velocity of the internal combustion engine during cranking varies depending on the crank angle of the internal combustion engine at rest, and this variation in the rate of increase of the internal combustion engine speed results in a variation in the moment of the engine's initial explosion. According to the methods for controlling the electric motor disclosed in Patent Document 1 and Patent Document 4, the aforementioned delay time is set without taking into account the variation in the rate of increase of the internal combustion engine speed. Therefore, the moment when the electric motor generates the limiting torque of the drive wheel torque cannot be precisely timed with the moment of the engine's initial explosion, and the generated limiting torque of the drive wheel torque cannot sufficiently achieve the desired effect.

[0004] The present invention was made with reference to the prior art described above. Consequently, it is an object of the present invention to provide a control device for a vehicle that allows an effective reduction of vibration resulting from the application of torque to the vehicle's drive wheels after the initial explosion of an internal combustion engine as a result of cranking the engine.

[0005] The above-mentioned problem is achieved according to the following modes of the present invention: According to a first mode of the invention, a control device for a vehicle is provided with an internal combustion engine as a drive power source and an electric motor that adjusts a torque transmitted to drive wheels, wherein the control device comprises: a control section configured to control the electric motor to generate a limiting torque of a drive wheel torque to limit a torque to be applied to drive wheels after an initial explosion of the internal combustion engine as a result of cranking the internal combustion engine to start the internal combustion engine, when a predetermined length of delay time has elapsed after a predetermined time before the moment of the initial explosion of the internal combustion engine, and a time setting section configuredto set the predetermined length of the delay time based on the operating speed of the internal combustion engine during cranking and one of the elements: the pre-start crank angle of the internal combustion engine at rest and the rate of increase of the operating speed of the internal combustion engine during cranking. According to an unclaimed second mode of the invention, the control device is configured according to the first mode of the invention such that the predetermined time shown above is a moment of generating a control instruction to initiate a fuel injection into the internal combustion engine, and the time setting section sets the length of the delay time based on the operating speed of the internal combustion engine at the moment of generating the control instruction described above and a pre-start crank angle of the internal combustion engine at rest. According to a third mode of the invention, the control device is configured according to the first mode of the invention such that the predetermined time indicated above is a moment of generating a control instruction to initiate fuel injection into the internal combustion engine, or a time at which a predetermined time has elapsed after the moment of generating the control instruction indicated above, and the time setting section determines the length of the delay time based on the operating speed of the internal combustion engine at the moment of generating the control instruction and the rate of increase of the operating speed of the internal combustion engine during a time period in the process of cranking the internal combustion engine, wherein the time period starts at the moment of generating the control instruction and has a length of the predetermined time.

[0006] According to the first mode of the invention, the length of the delay time is set based on the pre-start crankshaft angle of the internal combustion engine at rest or the rate of increase of the operating speed of the internal combustion engine during its cranking. In this context, it should be noted that the rate of increase of the operating speed of the internal combustion engine varies depending on the pre-start crankshaft angle of the internal combustion engine at rest, so that the length of the delay time, which is set based on the pre-start crankshaft angle, is determined taking into account the rate of increase of the internal combustion engine speed. Accordingly, it is possible to reduce the time difference between the moment of the initial combustion of the internal combustion engine and the moment of generation of the limiting torque of the drive wheel torque by the electric motor, a time difference caused by the variation in the rate of increase of the internal combustion engine speed.Consequently, it is possible to reduce the torque applied to the drive wheels after the initial explosion of the internal combustion engine, and it is correspondingly possible to effectively reduce any shock imparted to the vehicle during the internal combustion engine start control.

[0007] According to the second mode of the invention, the pre-start crankshaft angle of the internal combustion engine at rest is used to adjust the length of the delay time. In this context, it is noted that the rate of increase of the operating speed of the internal combustion engine varies depending on the pre-start crankshaft angle of the internal combustion engine at rest, so that it is possible to reduce the time difference between the moment of the initial explosion of the internal combustion engine and the moment of generation of the limiting torque of the drive wheel torque by the electric motor, without the need to calculate the rate of increase of the operating speed of the internal combustion engine.

[0008] According to the third mode of the invention, the rate of change of the operating speed of the internal combustion engine during the cranking of the internal combustion engine is used to adjust the length of the delay time, so that it is possible to precisely synchronize the moment of generation of the limiting torque of the drive wheel torque from the electric motor with the moment of the initial explosion of the internal combustion engine. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic view showing an arrangement of a hybrid vehicle to be controlled by a control device in the form of an electronic control unit according to a first embodiment of the present invention, and is also a block diagram showing main control sections of the control device for controlling several sections of the hybrid vehicle. Fig. Figure 2 is a functional block diagram showing the main control sections of the electronic control device of Fig. 1 shows. Fig. Figure 3 is a table showing an example of a time setting table used by the electronic control device to set the length of a delay time based on the operating speed of an internal combustion engine and the pre-start crank angle of the internal combustion engine. Fig. Figure 4 is a flowchart showing a main control operation of the electronic control device of Fig. 1 represents a compensation control routine for an initial internal combustion engine explosion, which is executed to reduce a shock due to an initial explosion of the internal combustion engine during an internal combustion engine start control. Fig. Figure 5 is a time graph showing changes in several parameters during the execution of the compensation control routine of the initial combustion engine explosion in the flowchart of Fig. 4 represents. Fig. Figure 6 is a functional block diagram showing main control sections of an electronic control device according to a second embodiment of the invention for a hybrid vehicle. Fig. 7 is a table that is an example of a time setting table used by the electronic control device of Fig. 6 is used to set a delay time length based on the operating speed of the internal combustion engine and a rate of increase of the internal combustion engine operating speed. Fig. Figure 8 is a flowchart showing a main control operation from the electronic control unit of Fig. 6 represents a compensation control routine for an initial internal combustion engine explosion, which is executed to reduce a shock due to the initial explosion of the internal combustion engine during an internal combustion engine start control. Fig. Figure 9 is a time graph showing changes in several parameters during the execution of the compensation control routine of an initial internal combustion engine explosion, as shown in the flowchart of Fig. 8 is shown, indicates. Fig. Figure 10 is a schematic view showing an arrangement of a power transmission system of a hybrid vehicle, which is based on the design in Fig. 1 is different, which is controlled by a control device according to the present invention. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0009] Preferred embodiments of this invention are described in detail by reference to the drawings. It should be understood that the drawings showing the embodiments have been simplified or modified as necessary and do not accurately represent the dimensions and shapes of several elements. FIRST VERSION

[0010] Reference is first made to Fig. Figure 1, which is a schematic view showing an arrangement of a hybrid vehicle 10 (hereinafter referred to as "vehicle 10") controlled by a control device according to the present invention, and which is also the block diagram showing the main control sections of the control device for controlling several sections of the vehicle 10. As shown in Fig. As shown in Figure 1, the vehicle 10 is equipped with an internal combustion engine 12, which serves as a drive power source, and an intermediate axle (T / A) in the form of a power transmission system 14. The power transmission system 14 includes a damper 18, an input shaft 20, a transmission section 22, a mating gear pair 24, a final gear pair 26, a differential gear assembly (reducing gear for a final speed) 28, and a pair of axles (drive shafts), right and left axles, 29, which are attached within a stationary element in the form of a housing 16 to a body of the vehicle 10, in the order of description viewed from the side of the internal combustion engine 12.The transmission section 22 has: a first electric motor MG1, a power distribution mechanism 32 configured to distribute a driving force from the internal combustion engine 12 to the first electric motor MG1 and an output gear 30, a gear mechanism 34 connected to the output gear 30, and a second electric motor MG2 connected to the output gear 30 by the gear mechanism 34 in a power-transmitting manner. The output gear 30 is an output rotating element of the transmission section 22 (power distribution mechanism 32). The mating gear pair 24 consists of the output gear 30 and a counter-driven gear 36. The input shaft 20 is connected at one end to the internal combustion engine 12 by the damper 18, so that the input shaft 20 is rotated by the engine 12.An oil pump 38 is connected to the other end of the input shaft 20 and is driven by the rotating motion of the input shaft 20, so that lubricant is supplied from the oil pump 38 to several parts of the power transmission system 14, such as the power distribution mechanism 32, the gear mechanism 34, and ball guides (not shown). In the power transmission system 14, which is constructed as described above, a driving force from the internal combustion engine 12 is obtained through the damper 18 and the input shaft 20, and a driving force from the second electric motor MG2 is transmitted to the output gear 30 and from the output gear 30 to a pair of drive gears 40 through the mating gear pair 24, the final gear pair 26, the differential gear assembly 28, and the pair of axles (drive shafts) 29, in the order described.The first electric motor MG1 corresponds to an electric motor of the vehicle 10, which is to be controlled by the control device according to the invention.

[0011] The power distribution mechanism 32 is a known single-pinion planetary gear system with rotating components (rotating elements) consisting of a first sun gear S1, a first carrier CA1, and a first ring gear R1. The first carrier CA1 supports a first compensating pinion P1, allowing the first compensating pinion P1 to rotate about its axis and about an axis of the planetary gear system. The first ring gear R1 meshes with the first sun gear S1 via the first compensating pinion P1. The power distribution mechanism 32 functions like a differential mechanism, capable of performing differential operation.In this power distribution mechanism 32, the first carrier CA1, which serves as a first rotating component RE1, is connected to the input shaft 20, namely to the internal combustion engine 12, and the first sun gear S1, which serves as a second rotating component RE2, is connected to the first electric motor MG1, while the first ring gear R1, which serves as a third rotating element RE3, is connected to the output gear 30. In the transmission section 22, where the first sun gear S1, the first carrier CA1, and the first ring gear R1 are rotatable relative to each other, an output from the internal combustion engine 12 is distributed to the electric motor MG1 to generate electrical power. The electrical power generated by the first electric motor MG1 is stored in an electrical power storage device 52 by a reverser 50.The inverter stores the power, and the second electric motor MG2 is operated with the electrical power generated by the first electric motor MG1. Accordingly, the transmission section 22 is placed, for example, in a continuously variable displacement state (electric CVT state), in which a transmission section 22 functions as an electrically controlled, continuously variable transmission of a speed ratio γ0, which is continuously variable. The speed ratio γ0 is equal to a ratio of an operating speed Ne of the internal combustion engine 12 (hereinafter referred to as "internal combustion engine speed Ne") with respect to an output speed Nout of the transmission section 22 (rotational speed Nout of the output gear 30).Specifically, the transmission section 22 functions as an electrically controlled differential section (electrically controlled, continuously variable transmission), in which a differential state of the power distribution mechanism 32 can be controlled by controlling an operating state of the first electric motor MG1 as an electric motor with differential state control. Accordingly, the transmission section 22 allows the internal combustion engine 12 to operate at an operating point where its fuel efficiency is highest, i.e., at a maximum fuel efficiency point. For example, the operating point of the internal combustion engine 12 ("internal combustion engine operating point") is represented by the internal combustion engine speed Ne and a torque Te of the internal combustion engine 12 (hereinafter referred to as "internal combustion engine torque Te"). This type of hybrid drive system is called a mechanical distribution type or split-type.

[0012] The gear mechanism 34 is a known single-pinion planetary gear system with rotating components consisting of a second sun gear S2, a second carrier CA2, and a second ring gear R2. The second carrier CA2 supports a second compensating pinion P2, allowing the second compensating pinion P2 to rotate about its axis and about an axis of the planetary gear system. The second ring gear R2 meshes with the second sun gear S2 via the second compensating pinion P2. In the gear mechanism 34, the second carrier CA2 is attached to the stationary element in the form of the housing 16 and is therefore held stationary. The second sun gear S2 is connected to the second electric motor MG2, while the second ring gear R2 is connected to the output gear 30.The planetary gear set of the gear mechanism has a gear ratio (number of teeth of the sun gear S2 / number of teeth of the ring gear R2) that is determined so that the gear mechanism 34 functions as a speed or rotational speed reduction device. When the second electric motor MG2 generates a vehicle drive torque, a rotary motion of the second electric motor MG2 is transmitted to the output gear 30, so that the rotational speed of the output gear 30 is reduced relative to the output speed of the second electric motor MG2, and consequently, the torque obtained through the output gear 30 is increased relative to the output torque of the second electric motor MG2.The output gear 30 is a composite gear that not only has functions of the ring gear R1 of the power distribution mechanism 32 and the ring gear R2 of the gear mechanism 34, but also a function of a counter-driven gear that meshes with and cooperates with the counter-driven gear 36 to constitute the counter-gear pair 24.

[0013] For example, each of the electric motors, first and second electric motors, MG1 and MG2, is a synchronous electric motor that has at least one function as an electric motor capable of converting electrical power into mechanical driving force and another function as an electric generator capable of converting mechanical driving force into electrical power. Preferably, each electric motor MG1, MG2 is a motor / generator that can be operated selectively as either an electric motor or an electric generator. For example, the first electric motor MG1 has the function of an electric generator capable of producing a regenerative torque that acts against the internal combustion engine torque Te and the function of an electric motor capable of starting the internal combustion engine 12, which has been at rest.On the other hand, the second electric motor MG2 has a function as a vehicle-propelling electric motor, serving as a vehicle propulsion power source that can be operated to generate a vehicle propulsion force, and a function as an electric generator that can be operated with a reverse propulsion force obtained from the drive wheels 40 to generate electrical power while generating regenerative torque.

[0014] The vehicle 10 is equipped with a control device in the form of an electronic control unit 80, which is configured to control several components of the vehicle. For example, the electronic control unit 80 contains a so-called microcomputer, which includes a CPU, a ROM, a RAM, and an input / output interface. The CPU performs control operations of the vehicle 10 by processing multiple signals according to control programs stored in the ROM, while utilizing a temporary data storage function of the RAM. For example, the control operations performed by the electronic control unit 80 include hybrid drive controls for the internal combustion engine 12, the first electric motor MG1, and the second electric motor MG2. The electronic control unit 80 can be constituted by two or more control units, which are exclusively assigned toto perform various control operations as well as output controls of the internal combustion engine 12 and output controls of the first and second electric motors MG1 and MG2. The electronic control device 80 receives several input signals, such as: an output signal from the speed sensor 60, indicating a crank angle Acr and the operating speed Ne of the internal combustion engine 12; an output signal from the speed sensor 62, indicating the rotational speed Nout of the output gear 30, corresponding to a running speed of the vehicle 10; an output signal from a speed sensor 64, indicating an operating speed Nmg1 of the first electric motor MG1 (hereinafter referred to as "MG1 speed Nmg1"); an output signal from a speed sensor 66, indicating an operating speed Nmg2 of the second electric motor MG2; and an output signal from a magnitude sensor 68 of an accelerator pedal operation.which indicates an operating amount Θacc of an accelerator pedal, an output signal from a battery sensor 70 indicating a temperature THbat, an electrical charging / discharging current Ibat, and a voltage Vbat of the electrical power storage device 52. These sensors 60 to 70 are provided in the vehicle 10. In addition, the electronic control device 80 generates several output signals for controlling several devices of the vehicle 10, as well as hybrid control instruction signals Shv, which include internal combustion engine control instruction signals applied to the internal combustion engine 12, and electric motor control instruction signals (alternating control instruction signals) applied to the reverser 50. The electronic control device 80 periodically calculates a state of charge (stored electrical power amount) SOC of the electrical power storage device 52 based on its temperature THbat.of the electrical charging / discharging current Ibat and the voltage Vbat.,

[0015] Fig. Figure 2 is the functional block diagram showing the main control sections of the electronic control device 80. As shown in Fig. As shown in Figure 2, the electronic control device 80 contains hybrid control means, that is, a hybrid control section 82.

[0016] For example, the hybrid control section 82 is configured to calculate a requested vehicle drive torque Touttgt as a requested drive force (an operator-requested drive force) of the vehicle 10 by a driver based on the operating amount Θacc of the accelerator pedal and the vehicle running speed V. Then, the hybrid control section 82 generates the hybrid control instruction signals Shv to control the drive power source (internal combustion engine 12 and second electric motor MG2) in order to obtain the calculated requested vehicle drive torque Touttgt, while taking into account a requested value of charging the electrical power storage device 52.

[0017] The hybrid control section 82 selectively sets one of predetermined vehicle drive modes according to the vehicle's operating state. The predetermined vehicle drive modes include: an engine drive mode (EV drive mode) in which only the second electric motor MG2 is operated as the drive power source while the internal combustion engine 12 is kept at rest; an internal combustion engine drive mode (reliable-state drive mode) in which at least the internal combustion engine 12 is operated as the drive power source, so that the engine torque Te is directly transmitted to the output gear 30 (drive gears 40), while the first electric internal combustion engine MG1 generates a regenerative torque that acts against the engine torque Te, and so that the second electric motor MG2 is operated as needed with electrical power generated by the first electric motor MG1.so that an output torque of the second electric motor MG2 is transmitted to the output gear 30, and a drive mode for internal combustion engine support (vehicle acceleration drive mode) in which the second electric motor MG2 is operated with the electrical power stored in the electrical power storage device 52 to generate a supporting drive torque to be added to the internal combustion engine torque Te. The required vehicle drive force shown above may be different from the required vehicle drive torque Touttgt [Nm] transmitted to the drive wheels 40, for example, a required drive force [N] to be transmitted to the drive wheels 40, a required drive power [W] to be transmitted to the drive wheels 40, a required output torque to be transmitted to the output gear 30,or a target output torque of the drive power source. Alternatively, the required vehicle drive force can be simply represented by the operating amount Θacc [%], an opening angle [%] of a throttle valve, or an input air quantity [g / sec] of the internal combustion engine 12.

[0018] Hybrid control section 82 establishes the engine drive mode when the vehicle's operating condition, represented by an actual value of the vehicle's running speed V and the required vehicle drive force (operating amount Θacc of the accelerator pedal or required vehicle drive torque Touttgt), falls within a predetermined engine drive range, which is obtained through experimentation or calculation and stored in memory. Conversely, hybrid control section 82 establishes the vehicle drive mode or the drive mode for internal combustion engine assistance when the vehicle's operating condition falls within a predetermined engine drive range. The engine drive range referred to above is a range in which the required vehicle drive force is lower than in the internal combustion engine drive range.The hybrid control section 82 is also configured to propel the vehicle 10 with operation of the internal combustion engine 12, even when the vehicle operating state falls within the engine drive range, in the following cases: when the vehicle 10 cannot be propelled in engine drive mode due to a limitation on the discharge of the electrical power storage device 52, wherein the limitation is determined on the basis of the amount of electrical power SOC stored in the electrical power storage device 52, and / or a maximum amount Wout of electrical power discharge from the electrical power storage device 52, which was determined according to the temperature THbat, wherein it is necessary for the electrical power storage device 52 to be charged, and wherein it is necessary for the internal combustion engine 12 or any device associated with the internal combustion engine 12 to be warmed up.

[0019] The hybrid control section 82 includes an internal combustion engine start control means or an internal combustion engine start control section 84, which is configured to start the internal combustion engine 12 when it is necessary for the internal combustion engine 12 to be started while the vehicle 10 is running in engine drive mode, as a result of, for example, an increase in the vehicle running speed V, an increase in the required vehicle drive force, a shortage of the electrical power amount SOC stored in the electrical power storage device 52, or a requirement to warm up the internal combustion engine 12.While the vehicle 10 is running in engine drive mode, the combustion engine start control section 84 determines, based on the increase in vehicle running speed V, the increase in required vehicle drive force, the scarcity of electrical power COD, or the need to warm up the combustion engine 12, whether it is necessary to start the combustion engine 12. If it is determined that it is necessary to start the combustion engine 12, the combustion engine start control section 84 implements a combustion engine start control in which the combustion engine 12 is cranked with a drive force from the first electric motor MG to increase its operating speed Ne, thus starting the combustion engine 12.Specifically, the control section for the internal combustion engine start 84 instructs the first electric motor MG1 to generate an output torque (hereinafter referred to as "MG1 torque Tmg1") as a cranking torque for the internal combustion engine to increase the internal combustion engine speed Ne with an increase in the MG1 speed Nmg1. When a predetermined time has elapsed after a moment of determination of the need to start the internal combustion engine 12, that is, when the internal combustion engine speed Ne has increased to a predetermined value above which the internal combustion engine 12 can operate independently, the control section for the internal combustion engine start 84 initiates a fuel injection into the internal combustion engine 12 and ignition of the internal combustion engine 12 in order to start the internal combustion engine 12.It is noted that the control section for the combustion engine start 84 corresponds to a control section of the control device according to the present invention.

[0020] Following an initial explosion of the internal combustion engine 12 during the combustion engine start control process, specifically during the cranking of the internal combustion engine 12, a torque is generated by the internal combustion engine 12 as a result of its initial explosion and applied to the drive wheels 40 via the damper 18, causing an undesirable jolt to the vehicle 10. Furthermore, the damper 18 is subjected to torsional stress and twisted due to the torque generated after the initial explosion of the internal combustion engine 12. This creates a risk of gears colliding with each other in the power transmission path between the internal combustion engine 12 and the drive wheels 40, and consequently, the generation of gear-collision noise when the twisted damper 18 returns to its original state. To reduce this risk,The combustion engine start control section 84 implements a compensation control for a combustion engine explosion to control the first electric motor MG1 in order to control a torque (hereinafter referred to as the limiting torque for the "drive wheel torque Tcon") to limit the torque to be applied to the drive wheels 40 (output gear 30) in synchronization with the initial explosion of the combustion engine 12. More specifically, the combustion engine start control section 84 controls the first electric motor MG1 to generate a sum Tsum (=Tmg1+Tcon) of the MG1 torque Tmg1 after the combustion engine start control and the limiting torque Tcon for a drive wheel torque (also called "compensation torque") shown above, which is determined to limit the torque.that is applied to the drive wheels 40 after the initial explosion of the internal combustion engine 12, when a predetermined length of delay time (waiting time) tset1 has elapsed after a predetermined time prior to the initial explosion of the internal combustion engine 12 during cranking, for example, after the moment of generating a control instruction to initiate fuel injection into the internal combustion engine 12 (hereinafter referred to as the "fuel injection instruction"), namely after the moment when a fuel reduction indicator is turned from an ON state to an OFF state. A direction and an order of magnitude of the limiting torque Tcon of the drive wheel torque are determined by experiment or calculation, such that the limiting torque Tcon of the drive wheel torque corresponds to the torque to be applied to the drive wheels 40 after the initial explosion of the internal combustion engine 12.This counteracts the effect. Furthermore, the length of the delay time tset1 is set so that the limiting torque Tcon of the drive wheel torque of the first electric motor MG1 occurs in synchronization with the initial explosion of the internal combustion engine 12. The method for setting the length of the delay time tset1 will also be described.

[0021] Following the compensation control for the initial combustion engine explosion, implemented by the combustion engine start control section 84, the torque to be applied to the drive wheels 40 after the initial explosion of the combustion engine 12 is restricted or reduced due to the generation of the sum Tsum of the MG1 torque Tmg1 and the limiting torque Tcon of the drive wheel torque from the first electric motor MG1, so that the generation of the vibration during the combustion engine start control is effectively reduced.Furthermore, the limiting torque Tcon of the drive wheel torque is a positive torque (driving torque) that acts to reduce the torsional stress imposed on the damper 18 after the initial explosion of the internal combustion engine 12. This means it increases the rotational speed of an output element of the damper 18 on the drive wheel 40 side, thus reducing the torsional stress imposed on the damper 18. Consequently, it is possible to reduce the risk of gears colliding in the power transmission path between the internal combustion engine 12 and the drive wheels 40, and the resulting gear-collision noise when the twisted damper 18 returns to its original state.

[0022] The hybrid control section 82 also includes a timing device or timing section 86, which is configured to set the length of the delay time tset1 from the moment the fuel injection instruction is generated to the internal combustion engine 12 until the moment the limiting torque Tcon of the drive wheel torque is generated. The length of the delay time tset1 is set by experiment or calculation such that the initial explosion of the internal combustion engine 12 occurs when the set length of the delay time tset1 has elapsed after the moment the fuel injection instruction is generated, namely, so that the limiting torque Tcon of the drive wheel torque is generated after the initial explosion. It should be noted that the timing section 86 corresponds to a timing section of the control device according to the present invention.

[0023] For example, the time from the moment the fuel injection instruction is generated to the moment of the initial explosion of the internal combustion engine 12 decreases with an increase in the internal combustion engine speed Ne at the moment the fuel injection instruction is generated, and with an increase in the rate of increase ΔNe of the internal combustion engine speed Ne during the process of internal combustion engine start control (during cranking the internal combustion engine 12). It is known that the rate of increase ΔNe of the internal combustion engine speed varies according to a crank angle Acr of the internal combustion engine 12 at rest (before its start), that is, a pre-start crank angle Acr of the internal combustion engine 12 at rest.In light of these facts, the timing section 86 sets the length of the delay time tset1 based on the internal combustion engine speed Ne at the moment the fuel injection instruction is generated during cranking of the internal combustion engine 12 and the pre-start crank angle Acr of the internal combustion engine 12 at rest. The timing section 86 stores a timing table (described in detail below) which is used to set the length of the delay time tset1 based on the internal combustion engine speed Ne at the moment the fuel injection instruction is generated and the pre-start crank angle Acr of the internal combustion engine 12 at rest.The timing section 86 is configured to read in an actual value Acrx of the pre-start crankshaft angle Acr of the internal combustion engine 12 at rest and an actual value Nex of the internal combustion engine speed Ne at the moment the fuel injection instruction is generated, and to set the length of the delay time tset1 according to the timing table. The internal combustion engine start control section 84 implements the internal combustion engine start control based on the set length of the delay time tset1 in order to reduce the time difference between the moment of the initial explosion of the internal combustion engine 12 and the moment the limiting torque Tcon of the drive wheel torque is generated.Namely, the control section for the combustion engine start 84 is configured to adjust the length of the delay time Tset1 taking into account not only the combustion engine speed Ne but also the pre-start crank angle Acr of the combustion engine 12 (that is, the rate of increase ΔNe of the combustion engine speed Ne), so that the generation of the limiting torque Tcon of the drive wheel torque from the first electric motor MG1 is exactly synchronized with the initial explosion of the combustion engine 12.

[0024] Fig. Table 3 shows an example of the timing table used by timing section 86 to set the length of the delay time (waiting time) tset1 based on the internal combustion engine speed Ne and the pre-start crankshaft angle Acr of the internal combustion engine 12 at rest. This timing table is obtained through experimentation or calculation. As shown in Fig. As shown in Figure 3, the timing table is defined in a two-dimensional coordinate system where the pre-start crankshaft angle Acr and the internal combustion engine speed Ne are taken on the corresponding axes. In the timing table, the internal combustion engine speed Ne is defined within a range between Ne1 and Nen, within which the internal combustion engine speed Ne is estimated to fall at the moment the fuel injection instruction is generated. The pre-start crankshaft angle Acr of the internal combustion engine 12 is defined within a range between -180° and +180°, within which the center crankshaft angle Acr is 0° when a piston of the internal combustion engine 12 is located at its top dead center. Specifically, in the timing table of Fig. 3 is the crank angle Acr1 - 180°, while the crank angle Acrm is +180°.

[0025] The time setting table of Fig. 3 is formulated such that the length of the delay time tset1 decreases with an increase in the internal combustion engine speed Ne, and such that the length of the delay time tset1 varies at a given value of the internal combustion engine speed Ne at the moment the fuel injection instruction is generated according to the pre-start crank angle Acr of the internal combustion engine 12. More specifically, the length of the delay time tset1 decreases when the pre-start crank angle Acr changes with an increase in the rate of increase ΔNe of the internal combustion engine speed Ne during the cranking of the internal combustion engine 12.In this regard, it is noted that the rate of increase ΔNe of the internal combustion engine speed Ne during the cranking of the internal combustion engine 12 after the pre-start crank angle Acr of the engine 12 varies depending on the type and number of cylinders of the internal combustion engine 12, so that the rate of increase ΔNe is obtained by experiment or calculation for the specific configuration of the internal combustion engine 12. It is noted that the length of the delay time tset1 is not determined according to the time setting table as shown in . Fig. 3 is shown, must be obtained, but can be obtained on the basis of an actual value Nex of the internal combustion engine speed Ne and an actual value Acrx of the pre-start crank angle Acr of the internal combustion engine 12 and according to a predetermined equation which contains the internal combustion engine speed Ne and the pre-start crank angle Acr as variables.

[0026] Fig. Figure 4 is the flowchart illustrating a main control operation of the electronic control device 80, namely a compensation control routine for an initial combustion engine explosion. This routine is executed to reduce the vibration transmitted to the vehicle and the gear-collision noises resulting from the initial explosion of the combustion engine 12 during the combustion engine start control (while cranking the combustion engine 12). The compensation control routine for the initial combustion engine explosion is executed simultaneously with the combustion engine start control, which is initiated after the determination of the need to start the combustion engine 12.

[0027] The control routine of Fig. Step 4 is initiated by step S1, corresponding to the function of timing section 86, to read the pre-start crankshaft angle Acrx of internal combustion engine 12. The control flow then proceeds to step S2, also corresponding to the function of timing section 86, to read the internal combustion engine speed Nex at the moment the fuel injection instruction is generated for internal combustion engine 12 (at the moment the fuel reduction indicator is switched off). The control flow then proceeds to step 3, also corresponding to the function of timing section 86, to set or determine the length of the delay time tset1 based on the actual crankshaft angle value Acrx and the actual internal combustion engine speed value Nex, which were read in the corresponding steps S1 and S2, and according to the timing table.The control flow then proceeds to step S4, which corresponds to the function of the combustion engine start control section 84, to delay the generation of the limiting torque Tcon of the drive wheel torque from the first electric motor MG1 for the length of the delay time tset1, which was set in step S3, after the moment the fuel injection instruction is generated (after the fuel saving indicator has been switched off). The control flow then proceeds to step S5, which also corresponds to the function of the combustion engine start control section 84, to implement the compensation control of the initial combustion engine explosion when the length of the delay time tset1 has elapsed after the moment the fuel injection instruction is generated.In the compensation control of the initial combustion engine explosion, the first electric motor MG1 is controlled to generate the sum Tsum of the MG1 torque Tmg1 to crank the combustion engine 12 (which changes according to a basic pattern of the cranking torque for the combustion engine) and the limiting torque of the drive wheel torque.

[0028] Fig. Figure 5 is a timing diagram showing changes in several parameters during the combustion engine start control (e.g., during the execution of the combustion engine cranking), when the compensation control routine of the initial combustion engine explosion, which is shown in the flowchart of Fig. Figure 4 is shown, and is implemented to reduce the risk of generating the shock imparted to the vehicle 10 and the gear-to-gear noises resulting from the initial explosion of the internal combustion engine 12. In the time diagram of Fig. 5. Time is taken along the horizontal axis, while the internal combustion engine speed Ne, the fuel reduction indicator, the MG1 torque Tmg1, the drive wheel torque limiting torque Tcon, and the internal combustion engine crank angle Acr are taken along the vertical axis.

[0029] Before time t1, the fuel reduction indicator is held in the ON state, so that the fuel supply to the internal combustion engine 12 is reduced and the internal combustion engine speed Ne is held at zero (the internal combustion engine is held at rest). At time t1, an instruction to start the internal combustion engine 12 is generated, and an increase in the torque Tmg1 of the first electric motor MG1 is initiated along the predetermined pattern of a basic cranking torque for the internal combustion engine, which is set in Fig. As shown in Figure 5, the process is initiated so that the internal combustion engine speed Ne is increased. The basic pattern of the internal combustion engine cranking value of the MG1 torque Tmg1 is predetermined to use it to crank the internal combustion engine 12 (to increase the internal combustion engine speed Ne). At this time t1, when the internal combustion engine start instruction is generated, the pre-start internal combustion engine crank angle Acrcx is read.

[0030] At time t2, the fuel injection instruction is generated; specifically, the fuel reduction indicator is switched from the ON state to the OFF state, and the combustion engine speed Nex is read at time t2. Additionally, the length of the delay time tset1 is set based on the pre-start combustion engine crank angle Acrx and the combustion engine speed Nex, so that the generation of the drive wheel torque limiting torque Tcon is delayed for the set delay time after time t2, when the fuel injection instruction is generated. At time t3, when the delay time tset1 has elapsed after time t2, the first electric motor MG1 is activated to generate the drive wheel torque limiting torque Tcon.More specifically, the first electric motor MG1 is controlled to generate the sum Tsum of the MG1 torque Tmg1 and the limiting torque Tcon of the drive wheel torque.Since the length of the delay time tset1 is set on the basis of the combustion engine speed Ne and the pre-start combustion engine crank angle Acr, according to which the rate of increase ΔNe of the combustion engine speed Ne varies, the limiting torque Tcon of the drive wheel torque is generated at the moment of the initial explosion of the combustion engine 12 taking into account the variation of the rate of increase ΔNe, so that the risk of generating a shock given to the vehicle 10 due to the torque applied to the drive wheels 40 after the initial explosion of the combustion engine 12 can be effectively reduced, and the risk of generating tooth-collision noise due to the torsional stress applied to the damper 18 after the initial combustion engine explosion can be effectively reduced.

[0031] As described above, the present embodiment is configured to adjust the length of the delay time tset1 based on the combustion engine speed Ne and the pre-start crankshaft angle Acr of the combustion engine 12 at rest. The rate of increase ΔNe of the combustion engine speed Ne varies depending on the pre-start crankshaft angle Acr of the combustion engine 12 at rest, so the length of the delay time tset1, which is set based on the pre-start combustion engine crankshaft angle Acr, is determined taking into account the rate of increase ΔNe of the combustion engine speed Ne. Accordingly, it is possible to reduce the time difference between the moment of the initial explosion of the combustion engine 12 and the moment of generation of the limiting torque Tcon of the drive wheel torque of the first electric motor MG1, the time difference of which is caused by the variation in the rate of increase ΔNe of the combustion engine speed Ne.Consequently, it is possible to precisely limit the torque applied to the drive wheels 40 after the initial explosion of the internal combustion engine 12, and it is therefore possible to effectively reduce the vibration transmitted to the vehicle 10 during the internal combustion engine start control. Furthermore, the present embodiment does not require any operator to calculate the rate of increase ΔNe of the internal combustion engine speed Ne, since the rate of increase ΔNe is estimated based on the pre-start crank angle Acr of the internal combustion engine 12 at rest.

[0032] Another embodiment of this invention is described. It is noted that the same reference numerals used in the first embodiment are used to identify identical components in the second embodiment, which are not described redundantly. SECOND VERSION

[0033] In the preceding first embodiment, the length of the delay time tset1 is set based on the internal combustion engine speed Ne and the pre-start crankshaft angle Acr of the internal combustion engine, according to which the rate of increase ΔNe of the internal combustion engine speed Ne varies. In the present second embodiment, the rate of increase ΔNe of the internal combustion engine speed Ne is calculated directly, and the calculated rate of increase ΔNe is used to set the length of the delay time tset2.

[0034] Fig. Figure 6 is the functional block diagram showing the main control sections of an electronic control device 102 according to the second embodiment of this invention for a hybrid vehicle 100. The electronic control device 102 according to this embodiment includes a hybrid control section 104, which contains a control section 106 for an internal combustion engine start and a timing section 108. Since the control section 106 for the internal combustion engine start in this second embodiment is fundamentally identical to the control section 84 for the internal combustion engine start in the first embodiment, the description of the control section 106 for the internal combustion engine start is omitted. It should be noted that the control section 106 for the internal combustion engine start corresponds to a control section of the control device according to the present invention.

[0035] The timing section 108 is configured to set the length of the delay time tset2 based on the operating speed Nex of the internal combustion engine 12 at the moment the fuel injection instruction is generated, and the rate of increase ΔNe of the internal combustion engine speed Ne during a predetermined time period tf in the cranking process of the internal combustion engine 12, the time period tf of which starts at the moment the fuel injection instruction is generated (at the moment the fuel reduction indicator is switched off). The timing section 108 reads the internal combustion engine speed Nex at the moment the fuel injection instruction is generated.Furthermore, the timing section 108 reads the combustion engine speed Nea at a time ta, which is the predetermined time period tf after the moment the fuel injection instruction is generated, and then calculates the rate of increase ΔNe of the combustion engine speed Ne by dividing a difference between the combustion engine speeds Nea and Nex by the predetermined time period tf, that is, according to an equation (Nea-Nex) / tf. It should be noted that the timing section 108 corresponds to a timing section of the control device according to the present invention.

[0036] The predetermined time period tf is a period corresponding to a difference (ta-t2), namely a period between the time ta of an inflection point A (in Fig. 9 shown and described below) of the MG1 torque Tmg1 and a time t2 (in Fig. 9 shown), which is the moment of generation of the fuel injection instruction. The MG1 torque Tmg1 is used to crank the internal combustion engine 12 according to a predetermined basic pattern of an internal combustion engine cranking value, as shown in Fig. 9 is displayed, controlled. Specifically, the MG1 torque Tmg1 is initially increased to a first value T1, held at this first value T1 for a predetermined length of time, decreased to a second value T2, which is smaller than the first value T1, held at the second value T2 for a predetermined length of time, and finally decreased to zero. As shown in Fig. As shown in Figure 9, the basic pattern of the internal combustion engine cranking value of the MG1 torque Tmg1 has an inflection point A, which is a time ta at which the length of time for which the MG1 torque Tmg1 is held at the value T2 ends and at which the decrease of the MG1 torque Tmg1 towards 0 is initiated. The basic pattern of the internal combustion engine cranking value of the MG1 torque Tmg1 is formulated to prevent the first explosion of the internal combustion engine 12 before the moment of inflection point A. The timing section 108 is configured to calculate the rate of increase ΔNe of the internal combustion engine speed Ne based on the internal combustion engine speed Nex at the moment the fuel injection instruction is generated, the internal combustion engine speed Nea at the moment of inflection point A, and the predetermined time period tf (=ta-t2) shown above.

[0037] The timing section 108 stores a timing table (a two-dimensional table, described in detail below) used to set the length of the delay time tset2 based on the internal combustion engine speed Nex and the rate of increase ΔNex of the internal combustion engine speed Ne. The timing section 108 is configured to set the length of the delay time tset2 according to the timing table, and based on the internal combustion engine speed Nex, at the moment the fuel injection instruction is generated and the calculated rate of increase ΔNex of the internal combustion engine speed Nex is calculated. The control section 106 for an internal combustion engine start implements the internal combustion engine start control based on the set length of the delay time tset2.More specifically, the control section 106 for starting the internal combustion engine controls the first electric motor MG1 to generate the limiting torque Tcon of the drive wheel torque in addition to the MG1 torque Tmg1, in order to start the internal combustion engine 12, when the set length of the delay time tset2 has elapsed after time ta, which corresponds to the turning point A at which the predetermined time period tf has expired at the moment the fuel injection instruction is generated. Time ta corresponds to the predetermined time of the present invention.

[0038] Fig. Table 7 shows an example of the time setting table (ratio table, two-dimensional table) provided by the electronic control device 102. Fig. Section 6 is used to set the length of the delay time (waiting time) tset2 from the time ta of the inflection point A to the moment the limiting torque Tcon of the drive wheel torque is generated. This time setting table is obtained through experimentation or calculation. As described in Fig. As shown in Figure 7, the timing table is defined in a two-dimensional coordinate system in which the internal combustion engine speed Ne at the moment the fuel injection instruction is generated and the rate of increase ΔNe of the internal combustion engine speed Ne are taken on the corresponding of the two axes. More specifically, the timing table is formulated such that the internal combustion engine speed Ne is defined within a range between Ne1 and Nen, into which the internal combustion engine speed Ne is estimated to fall at the moment the fuel injection instruction is generated to the engine 12, while the rate of increase ΔNe of the internal combustion engine speed Ne is similarly defined within a range between ΔNe1 and ΔNem, into which the rate of increase ΔNe is estimated to fall during the cranking of the internal combustion engine 12.The timing section 108 sets the length of the delay time tset2 based on an actual value Nex of the internal combustion engine speed Ne and an actual value ΔNex of the rate of increase ΔNe of the internal combustion engine speed Ne, according to the timing table. It should be noted that the length of the delay time tset2 is not determined according to the timing table as shown in . Fig. 7 is shown, but can also be obtained on the basis of the actual value Nex of the combustion engine speed Ne and the actual value ΔNex of the rate of increase ΔNe and according to a predetermined equation which contains the combustion engine speed Ne and the rate of increase ΔNe as variables.

[0039] Fig. Figure 8 is the flowchart that shows a main control operation of the electronic control device 102 of Fig. Figure 6 represents a compensation control routine for an initial combustion engine explosion, which is executed to reduce the vibration imparted to the vehicle 10 and the gear-collision noise due to the initial explosion of the combustion engine 12 during the combustion engine start control (during cranking of the combustion engine 12). The compensation control routine for the initial combustion engine explosion is executed simultaneously with the combustion engine start control, which is initiated after the need to start the combustion engine 12 has been determined.

[0040] The control routine of Fig. Step 8 is executed with a step S10, corresponding to the function of the timing section 108, to read the internal combustion engine speed Nex at the moment the fuel injection instruction is generated (i.e., when the fuel reduction indicator is switched off). The control flow then proceeds to a step S11, also corresponding to the function of the timing section 108, to calculate the rate of increase ΔNex of the internal combustion engine speed Ne during the time period tf from the moment the fuel injection instruction is generated to the moment of inflection point A of the MG1 torque Tmg1.The control flow then proceeds to step S12, which also corresponds to the function of the timing section 108, to set the length of the delay time tset2 based on the internal combustion engine speed Nex read in step S10, and the rate of increase ΔNex of the internal combustion engine speed value Ne calculated in step S11, and according to the timing table shown in . Fig. As shown in Figure 7, the control flow then proceeds to step S13, which corresponds to the function of the control section for the internal combustion engine start. This step delays the generation of the limiting torque Tcon of the drive wheel torque from the first electric motor MG1 in order to implement the compensation control for the initial internal combustion engine explosion when the length of the delay time tset2 has elapsed after time ta. During the compensation control of the initial internal combustion engine explosion, the first electric motor MG1 is controlled to generate the sum Tsum of the MG1 torque Tmg1 to crank the internal combustion engine 12 (which varies according to the basic pattern of the internal combustion engine crank torque) and the limiting torque Tcon of the drive wheel torque.

[0041] Fig. Figure 9 is the timing diagram showing changes in several parameters during the combustion engine start control (especially during the execution of the combustion engine cranking), while the compensation control routine for the initial combustion engine explosion, which is shown in the flowchart of Fig. 8 is shown, is carried out to reduce the risk of generating the shock that is given to the vehicle 10 and the generation of the gear-to-gear noises due to the initial explosion of the internal combustion engine 12.

[0042] Before time t1, the fuel reduction indicator is held in the ON state, thus reducing the fuel supply to the internal combustion engine and maintaining the internal combustion engine speed Ne at zero (the internal combustion engine 12 is held at rest). At this time t1, a command to start the internal combustion engine 12 is generated, and an increase in the torque tmg1 of the first electric motor MG1 is initiated along the predetermined pattern of the basic cranking torque for the internal combustion engine, thus increasing the internal combustion engine speed Ne.

[0043] At time t2, the fuel injection instruction is generated, specifically, the fuel reduction indicator is switched from the ON state to the OFF state. At time ta, corresponding to the turning point A, the rate of increase ΔNex of the combustion engine speed Nex during the predetermined time period tf between time t2 and time ta is calculated, and the length of the delay time tset2 is set based on the combustion engine speed Nex and the calculated rate of increase ΔNex of the combustion engine speed Nex. The generation of the limiting torque Tcon of the drive wheel torque is delayed for the set length of the delay time tset2 from time ta. At time t3, when the length of the delay time tset2 has elapsed after time ta, the electric motor MG1 is controlled to generate the limiting torque Tcon of the drive wheel torque.Since the length of the delay time tset2 is set based on the combustion engine speed Nex and the calculated rate of increase ΔNex of the combustion engine speed Nex, the limiting torque Tcon of the drive wheel torque is generated at the moment of the initial explosion of the combustion engine 12 without taking into account the variation of the rate of increase ΔNe, so that the risk of generating the vibration imparted to the hybrid vehicle 100 due to the torque applied to the drive wheels 40 after the initial explosion of the combustion engine 12 can be effectively reduced. Furthermore, the risk of generating gear-to-gear noise due to the torsional stress applied to the damper 18 can be effectively reduced.

[0044] As described above, the second embodiment is configured to adjust the length of the delay time tset2 based on the rate of increase ΔNe of the combustion engine speed Ne during the cranking of the combustion engine 12, so that it is possible to precisely synchronize the moment of generation of the limiting torque Tcon of the drive wheel torque of the first electric motor MG1 with the moment of the initial explosion of the combustion engine 12. Consequently, it is possible to reduce the torque to be applied to the drive wheels 40 after the initial explosion of the combustion engine 12, and it is also correspondingly possible to effectively reduce the shock to be imparted to the hybrid vehicle 100 during the combustion engine start control.

[0045] While the preferred embodiments of this invention have been explained in detail by reference to the drawings, it is to be understood that the invention can be implemented differently.

[0046] In the embodiments described above, the control device is provided to control the hybrid vehicle 10, 100, which is equipped with the first electric motor MG1, the power distribution mechanism 32 for distributing the drive power of the internal combustion engine 12 to the first electric motor MG1 and the drive wheels 40, and the second electric motor MG2, which is operationally connected to the power distribution mechanism 32 by the gear mechanism 34. Although the control device according to the invention is suitable for any other type of hybrid vehicle, for example, for a hybrid vehicle 200, which is in Fig. As shown in Figure 10, the hybrid vehicle 200 can be used. It is equipped with a drive power source in the form of an internal combustion engine 202 and an electric motor MG, and a power transmission system 204. As shown in Figure 10, the hybrid vehicle 200 is equipped with a drive power source in the form of an internal combustion engine 202 and an electric motor MG, and a power transmission system 204. Fig. As shown in Figure 10, the power transmission system 204 comprises a clutch K0, a torque converter 208, and a step-variable transmission section 210, which is housed within a stationary element in the form of a casing 206 attached to the body of the hybrid vehicle 200, in the order described from the side of the internal combustion engine 202. The power transmission system 204 includes a differential gear assembly 212 and axles 214. The torque converter 208 has a pump impeller 208a, which is connected to the internal combustion engine 202 via a clutch K0 and directly to the electric motor MG, and a turbine impeller 208b, which is directly connected to the step-variable transmission section 210.In the power transmission system 204, a drive force from the internal combustion engine 202 and / or a drive force from the electric motor MG is / are transmitted to the drive wheels 216 via the clutch K0 (in which the drive force of the internal combustion engine 202 is transmitted), the torque converter 208, the step-variable transmission section 210, the differential gear assembly 212, and the axles 214. The step-variable transmission section 210 is an automatic transmission that constitutes part of a power transmission path between the drive power sources (internal combustion engine 202 and electric motor MG) and the drive wheels 216, and which is switched by the engagement of at least one of a plurality of coupling devices.The vehicle 200 is equipped with a reverser 218, an electrical power storage device in the form of a battery 220 to which electrical power is supplied by the reverser 218 from the electric motor MG and from this to the electric motor MG, and a control device in the form of an electronic control device 222.

[0047] When it is necessary to start the internal combustion engine 202, the electronic control device 222 implements an internal combustion engine start control in which the clutch K0 is placed in the engaged state, the electric motor MG is controlled to generate a cranking torque for the internal combustion engine Tmg in order to crank the internal combustion engine 202 to increase the internal combustion engine speed Ne, and the internal combustion engine 202 is started with a fuel injection darein and an ignition after a predetermined length of time has elapsed and the internal combustion engine speed Ne has been increased to a value at which the internal combustion engine 202 can operate independently.The electronic control device 22 instructs the electric motor MG to generate a limiting torque Tcon of a drive wheel torque to limit a torque to be applied to the drive wheels 216 after an initial explosion of the internal combustion engine 202, when a predetermined length of a delay time tset has elapsed after the moment of generating a fuel injection instruction.The electronic control device 222 for the vehicle 200 is also configured to adjust the length of the delay time tset based on the internal combustion engine speed Ne and the pre-start crank angle Acr of the internal combustion engine 202 at rest, or the rate of increase ΔNe of the internal combustion engine speed Ne during cranking of the internal combustion engine 202, so that the limiting torque Tcon of the drive wheel torque is generated at the moment of the initial explosion of the internal combustion engine 202, thereby effectively reducing the vibration imparted to the hybrid vehicle 200 due to the initial explosion of the internal combustion engine 202. Essentially, the principle of the present invention is applicable to any vehicle equipped with a motor serving as a drive power source and an electric motor whose output torque is transmitted to the drive wheels, and in which the output torque of the electric motor is adjustable.Although the vehicle 200 is equipped with a fluid-operated power transmission device in the form of the torque converter 208, the torque converter 208 can be replaced by any other type of fluid-operated power transmission device, such as a fluid coupling that does not have a torque amplification function. Furthermore, the torque converter 208 need not be provided or can be replaced by a simple clutch device.

[0048] In the first embodiment shown, the limiting torque Tcon of the drive wheel torque is generated by the electric motor MG1, which produces the MG1 torque Tmg1, to start the internal combustion engine 12. However, the second electric motor MG2 can generate a limiting torque Tcon' of the drive wheel torque to limit the torque applied to the drive wheels 40 after the initial explosion of the internal combustion engine 12. Specifically, the second electric motor can generate the limiting torque Tcon' of the drive wheel torque to limit the torque applied to the drive wheels 40 after the initial explosion of the internal combustion engine 12 once the predetermined delay time tset1 has elapsed after the moment the fuel injection instruction is generated.In this case, where the second electric motor MG2 generates the limiting torque Tcon', the vibration transmitted to the vehicle 10 after the initial explosion of the internal combustion engine 12 can be reduced. Essentially, the control device according to the present invention is applicable to any vehicle, with an adjustable output torque from its electric motor transmitted to the drive wheels. It should be noted that when the vehicle 10 is equipped with the second electric motor MG2 to generate the limiting torque Tcon' of the drive wheel torque, the torsional stress applied to the damper 18 is not reduced by the limiting torque of the drive wheel torque. Therefore, it is rather difficult to reduce the risk of gear-collision noises due to the torsional stress applied to the damper 18.

[0049] In the first embodiment, the time setting table is used to determine the length of the delay time tset1, which is specified in Fig. Figure 3 is formulated such that the pre-start crank angle Acr of the internal combustion engine 12 is within the range of -180° to +180°. Although the length of the delay time tset1 does not have to be within the entire range of the crank angle Acr, it can be within a limited range of the crank angle Acr, for example, within a range of -90° to +90°.

[0050] In the second embodiment shown, the time setting section 108 calculates the rate of increase ΔNex of the combustion engine speed Nex and sets the length of the delay time tset2 based on the combustion engine speed Nex and the calculated rate of increase ΔNex of the combustion engine speed Nex. Although the rate of increase ΔNe of the combustion engine speed Ne can be replaced by the difference (=Nea-Nex) between the combustion engine speed Nea at the moment of inflection point A and the combustion engine speed Nex at the moment the fuel injection instruction is generated, if the time period tf is constant.

[0051] In the second embodiment, the time setting section 108 calculates the rate of increase ΔNex of the combustion engine speed Nex during the time period tf from the moment the fuel injection instruction is generated to the combustion engine 12 until the moment of the inflection point A. Although the time period does not necessarily end at the moment of the inflection point A, it may end at a time before the moment of the initial explosion of the combustion engine 12.

[0052] In the second embodiment, the generation of the limiting torque Tcon of the drive wheel torque is delayed until the length of the delay time tset2 has elapsed after the predetermined time period tf from the moment the fuel injection instruction is generated to the internal combustion engine 12 until the moment of the turning point A. The limiting torque Tcon of the drive wheel torque can be generated even if the set length of the delay time tset2 has elapsed after the moment the fuel injection instruction is generated to the internal combustion engine 12. In this regard, it should be noted that the length of the delay time tset2 can be changed as needed, depending on the time at which the delay time tset2 begins.

[0053] It should be understood that the embodiments and modifications described above are given solely for illustrative purposes, and that the present invention can be carried out with several other changes and improvements that may occur to those skilled in the art. REFERENCE MARK LIST 10, 100, 200 hybrid vehicle (vehicle) 12, 202 Internal combustion engine 40, 216 drive wheels 80, 102, 222 Electronic control device (control unit) 84, 106 Control section for the internal combustion engine start (control section) 86, 108 Time setting section MG1 First electric motor (Electric Motor) MG Electric Motor

Claims

[1] Control device (80; 102; 222) for a vehicle (10; 100; 200) equipped with a motor (12; 202) and an electric motor (MG1; MG) which adjusts a torque to be transmitted to the drive wheels (40; 216), wherein the control device comprises: a control section (84; 106) configured to control the electric motor (MG1; MG) to generate a limiting torque (Tcon) for a drive wheel torque to limit a torque to be applied to the drive wheels (40; 216) at the initial explosion of the motor (12; 202) as a result of cranking the motor to start the motor, when a predetermined length of delay time (tset1; tset2; tset) has elapsed after a predetermined time before a moment of the initial explosion of the motor, and a time setting section (86; 108) configured to set the predetermined length of the delay time based on an operating speed (Ne) of the engine during engine cranking and one of the elements, pre-start crank angle (Acr) of the engine at rest and rate of rise (ΔNe) of the operating speed of the engine during cranking, characterized by , that the predetermined time is a moment (t2) of the generation of a control instruction to initiate a fuel injection into the engine (12; 202) or a time (ta) at which a predetermined time (tf) has elapsed after the moment of the generation of the control instruction, and the time setting section (108) sets the length of the delay time (tset2) based on the operating speed (Nex) of the motor at the moment the control instruction is generated and the rate of increase (ΔNex) of the operating speed of the motor during a time period in the process of cranking the motor, where the time period begins at the moment the control instruction is generated and has a length of the predetermined time (tf).

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