JP2009209978A - Vehicle starting control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control device capable of avoiding a fastening shock of a second fastening element regardless of an inertia change on the driving wheel side. <P>SOLUTION: When transferring to complete fastening from slip fastening by a starting control means, when inertia of a driving wheel is smaller than a predetermined value, predetermined fastening torque capacity is reduced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a start control device for a vehicle that starts by slip fastening of a fastening element.

The technique of patent document 1 is disclosed as a vehicle start control device. This publication includes a first fastening element that connects and disconnects the engine and the motor, and a second fastening element that connects and disconnects the motor and the drive wheel, and has an engine use travel mode in which the engine travels while being included in the power source. Even when the minimum gear ratio (for example, 1st speed) is selected, including when starting, the second fastening element is slipped at an extremely low speed that is lower than the minimum speed at which the engine can stand by itself. One that travels while ensuring rotation is known. Further, in this publication, when starting, the torque of the engine and the motor is determined based on the accelerator request, and the transmission torque of the second fastening element is controlled so that the input rotational speed to the second fastening element becomes substantially constant is doing.
JP 2001-263383 A

  However, the apparent inertia (hereinafter referred to as inertia) required to rotate the drive wheels in any case due to a decrease in the load for driving the vehicle forward on a downhill or a decrease in the road surface μ, for example. May decrease. Then, the rotational speed increase speed on the drive wheel side increases rapidly, and the fastening through an appropriate slip state cannot be maintained (hereinafter, the above state is collectively referred to as “the state where the inertia of the drive wheel is reduced”). ). Therefore, there is a problem that a fastening shock occurs. This problem occurs not only in hybrid vehicles but also in vehicles that are not equipped with a motor and that start by slip fastening of fastening elements.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle control device capable of avoiding the fastening shock of the second fastening element regardless of the inertia change on the drive wheel side.

  In order to achieve the above object, in the present invention, when the inertia of the drive wheel is smaller than a predetermined value at the time of transition from slip fastening to complete fastening by the start control means, the predetermined fastening torque capacity is reduced. .

  Therefore, in the vehicle start control device of the present invention, even if the inertia of the drive wheel is reduced, it is possible to suppress a sudden increase in the number of rotations on the drive wheel side of the fastening element, thereby suppressing the fastening shock. be able to. Moreover, heat generation of the fastening element can be suppressed by reducing the fastening torque capacity.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for realizing a vehicle start control device of the present invention will be described below based on an embodiment shown in the drawings.

  First, the drive system configuration of the hybrid vehicle will be described. FIG. 1 is an overall system diagram showing a hybrid vehicle by rear wheel drive to which the engine start control device of the first embodiment is applied. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a first clutch CL1, a motor generator MG, a second clutch CL2, an automatic transmission AT, a propeller shaft PS, It has a differential DF, a left drive shaft DSL, a right drive shaft DSR, a left rear wheel RL (drive wheel), and a right rear wheel RR (drive wheel). FL is the front left wheel and FR is the front right wheel.

  The engine E is, for example, a gasoline engine, and the valve opening degree of the throttle valve and the like are controlled based on a control command from the engine controller 1 described later. The engine output shaft is provided with a flywheel FW.

  The first clutch CL1 is a clutch interposed between the engine E and the motor generator MG, and the control created by the first clutch hydraulic unit 6 based on a control command from the first clutch controller 5 described later. Fastening / release including slip fastening is controlled by hydraulic pressure.

  The motor generator MG is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator, and the three-phase AC generated by the inverter 3 is generated based on a control command from a motor controller 2 described later. It is controlled by applying. The motor generator MG can operate as an electric motor that is driven to rotate by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “power running”), or when the rotor is rotated by an external force. Can function as a generator that generates electromotive force at both ends of the stator coil to charge the battery 4 (hereinafter, this operation state is referred to as “regeneration”). Note that the rotor of the motor generator MG is connected to the input shaft of the automatic transmission AT via a damper (not shown).

  The second clutch CL2 is a clutch interposed between the motor generator MG and the left and right rear wheels RL and RR, and is generated by the second clutch hydraulic unit 8 based on a control command from the AT controller 7 described later. The fastening / release including slip fastening is controlled by the control hydraulic pressure.

  The automatic transmission AT is a transmission that automatically switches the stepped gear ratio such as 5 forward speeds, 1 reverse speed, etc. according to the vehicle speed, accelerator opening, etc., and the second clutch CL2 is newly added as a dedicated clutch However, some frictional engagement elements are used among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT. Details will be described later.

  The output shaft of the automatic transmission AT is connected to the left and right rear wheels RL and RR via a propeller shaft PS, a differential DF, a left drive shaft DSL, and a right drive shaft DSR as vehicle drive shafts. The first clutch CL1 and the second clutch CL2 are, for example, wet multi-plate clutches that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid.

  This hybrid drive system has three travel modes according to the engaged / released state of the first clutch CL1. The first travel mode is an electric vehicle travel mode (hereinafter abbreviated as “EV travel mode”) as a motor use travel mode that travels using only the power of the motor generator MG as a power source with the first clutch CL1 opened. It is. The second travel mode is an engine use travel mode (hereinafter abbreviated as “HEV travel mode”) in which the first clutch CL1 is engaged and the engine E is included in the power source. The third travel mode is an abbreviated engine use slip travel mode (hereinafter referred to as “WSC travel mode”) in which the second clutch CL2 is slip-controlled while the first clutch CL1 is engaged and the engine E is included in the power source. ). This mode is a mode in which creep running can be achieved particularly when the battery SOC is low or the engine water temperature is low. When transitioning from the EV travel mode to the HEV travel mode, the first clutch CL1 is engaged and the engine is started using the torque of the motor generator MG.

  The “HEV travel mode” has three travel modes of “engine travel mode”, “motor assist travel mode”, and “travel power generation mode”.

  In the “engine running mode”, the drive wheels are moved using only the engine E as a power source. In the “motor assist travel mode”, the drive wheels are moved by using the engine E and the motor generator MG as power sources. The “running power generation mode” causes the motor generator MG to function as a generator at the same time as the drive wheels RR and RL are moved using the engine E as a power source.

  During constant speed operation or acceleration operation, motor generator MG is operated as a generator using the power of engine E. Further, during deceleration operation, the braking energy is regenerated and generated by the motor generator MG and used for charging the battery 4.

  Further, as a further mode, there is a power generation mode in which the motor generator MG is operated as a generator using the power of the engine E when the vehicle is stopped.

  Next, the control system of the hybrid vehicle will be described. As shown in FIG. 1, the hybrid vehicle control system according to the first embodiment includes an engine controller 1, a motor controller 2, an inverter 3, a battery 4, a first clutch controller 5, and a first clutch hydraulic unit 6. The AT controller 7, the second clutch hydraulic unit 8, the brake controller 9, and the integrated controller 10 are configured. The engine controller 1, the motor controller 2, the first clutch controller 5, the AT controller 7, the brake controller 9, and the integrated controller 10 are connected via a CAN communication line 11 that can exchange information with each other. Has been.

  The engine controller 1 inputs the engine speed information from the engine speed sensor 12, and controls the engine operating point (Ne: engine speed, Te: engine torque) according to the target engine torque command from the integrated controller 10, etc. For example, to a throttle valve actuator (not shown). Information such as the engine speed Ne is supplied to the integrated controller 10 via the CAN communication line 11.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor generator MG, and according to a target motor generator torque command from the integrated controller 10 or the like, the motor operating point (Nm: motor generator) of the motor generator MG. A command for controlling the rotation speed (Tm: motor generator torque) is output to the inverter 3. The motor controller 2 monitors the battery SOC indicating the state of charge of the battery 4. The battery SOC information is used as control information for the motor generator MG and is supplied to the integrated controller 10 via the CAN communication line 11. Is done.

  The first clutch controller 5 inputs sensor information from the first clutch hydraulic pressure sensor 14 and the first clutch stroke sensor 15, and according to the first clutch control command from the integrated controller 10, the first clutch CL1 is engaged / released. A command to control is output to the first clutch hydraulic unit 6. Information on the first clutch stroke C1S is supplied to the integrated controller 10 via the CAN communication line 11.

  The AT controller 7 inputs sensor information from the accelerator opening sensor 16, the vehicle speed sensor 17, the second clutch hydraulic pressure sensor 18, and an inhibitor switch that outputs a signal corresponding to the position of the shift lever operated by the driver. 10 is output to the second clutch hydraulic unit 8 in the AT hydraulic control valve in response to the second clutch control command from 10. Information on the accelerator pedal opening APO, the vehicle speed VSP, and the inhibitor switch is supplied to the integrated controller 10 via the CAN communication line 11.

  The brake controller 9 inputs sensor information from a wheel speed sensor 19 and a brake stroke sensor 20 that detect the wheel speeds of the four wheels. For example, when the brake is depressed, braking is performed with respect to the required braking force obtained from the brake stroke BS. When the braking force alone is insufficient, the regenerative cooperative brake control is performed based on the regenerative cooperative control command from the integrated controller 10 so that the shortage is supplemented by the mechanical braking force (braking force by the friction brake).

  The integrated controller 10 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The integrated controller 10 detects the motor rotational speed Nm, and the second clutch output rotational speed N2out. A second clutch output speed sensor 22 for detecting the second clutch, a second clutch torque sensor 23 for detecting the second clutch transmission torque capacity TCL2, a brake hydraulic pressure sensor 24, and a temperature sensor 10a for detecting the temperature of the second clutch CL2. The information from the G sensor 10b for detecting the longitudinal acceleration and the information obtained through the CAN communication line 11 are input.

  The integrated controller 10 also controls the operation of the engine E according to the control command to the engine controller 1, the operation control of the motor generator MG based on the control command to the motor controller 2, and the first control command to the first clutch controller 5. Engagement / release control of the clutch CL1 and engagement / release control of the second clutch CL2 by a control command to the AT controller 7 are performed.

  Below, the control calculated by the integrated controller 10 of Example 1 is demonstrated using the block diagram shown in FIG. For example, this calculation is performed by the integrated controller 10 every control cycle of 10 msec. The integrated controller 10 includes a target driving force calculation unit 100, a mode selection unit 200, a target charge / discharge calculation unit 300, an operating point command unit 400, and a shift control unit 500.

  The target driving force calculation unit 100 calculates a target driving force tFoO from the accelerator pedal opening APO and the vehicle speed VSP using the target driving force map shown in FIG.

  The mode selection unit 200 includes a road surface gradient estimation calculation unit 201 that estimates a road surface gradient based on the detection value of the G sensor 10b. The road surface gradient estimation calculation unit 201 calculates the actual acceleration from the wheel speed acceleration average value of the wheel speed sensor 19 and the like, and estimates the road surface gradient from the deviation between the calculation result and the G sensor detection value.

  In addition, the mode selection unit 200 includes a downhill determination unit 202 that determines whether or not the estimated road surface gradient is a downhill of a predetermined value or less. Further, a target second clutch engagement torque capacity correction unit 203 that corrects a target second clutch engagement torque capacity calculated in an operating point command unit 400 described later when a downhill is determined is provided. A specific correction amount will be described later.

  Next, the mode map will be described. FIG. 5 shows a normal mode map. The normal mode map has an EV travel mode, a WSC travel mode, and an HEV travel mode, and calculates the target mode from the accelerator pedal opening APO and the vehicle speed VSP. However, even if the EV travel mode is selected, if the battery SOC is equal to or lower than the predetermined value, the “HEV travel mode” or the “WSC travel mode” is forcibly set as the target mode.

  In the normal mode map of FIG. 5, the HEV → WSC switching line has a rotational speed smaller than the idle rotational speed of the engine E when the automatic transmission AT is in the first speed in the region below the predetermined accelerator opening APO1. It is set in a region lower than the lower limit vehicle speed VSP1. Further, since a large driving force is required in a region where the accelerator opening APO1 is equal to or greater than the predetermined accelerator opening APO1, the WSC travel mode is set up to a vehicle speed VSP1 ′ region that is higher than the lower limit vehicle speed VSP1. When the battery SOC is low and the EV travel mode cannot be achieved, the WSC travel mode is selected even when starting.

  When the accelerator pedal opening APO is large, it may be difficult to achieve the request with the engine torque corresponding to the engine speed near the idle speed and the torque of the motor generator MG. Here, more engine torque can be output if the engine speed increases. From this, if the engine speed is increased and a larger torque is output, even if the WSC drive mode is executed up to a vehicle speed higher than the lower limit vehicle speed VSP1, the WSC drive mode is changed to the HEV drive mode in a short time. be able to. This case corresponds to the WSC region extended to the lower limit vehicle speed VSP1 ′ shown in FIG.

  The target charge / discharge calculation unit 300 calculates the target charge / discharge power tP from the battery SOC using the target charge / discharge amount map shown in FIG.

  When SOC ≧ 50%, the EV driving mode area appears in the normal mode map of FIG. Once the EV driving mode area appears in the mode map, this area continues to appear until the SOC drops below 35%.

  When SOC <35%, the EV drive mode area disappears in the normal mode map of FIG. When the EV drive mode area disappears from within the mode map, this area continues to disappear until the SOC reaches 50%.

  The operating point command unit 400 uses the accelerator pedal opening APO, the target driving force tFoO, the target mode, the vehicle speed VSP, and the target charging / discharging power tP as a target for reaching the operating point, as a transient target engine torque. And a target motor generator torque, a target second clutch engagement torque capacity, a target shift stage of the automatic transmission AT, and a first clutch solenoid current command are calculated. Further, the operating point command unit 400 is provided with an engine start control unit that starts the engine E when the EV travel mode is changed to the HEV travel mode.

  The shift control unit 500 drives and controls the solenoid valve in the automatic transmission AT so as to achieve the target second clutch engagement torque capacity and the target shift speed according to the shift schedule shown in the shift map. In the shift map, a target gear position is set in advance based on the vehicle speed VSP and the accelerator pedal opening APO.

[About WSC drive mode]
Next, details of the WSC travel mode will be described. The WSC travel mode is characterized in that the engine E is maintained in an operating state, and has high responsiveness to a required driving force change. Specifically, the first clutch CL1 is completely engaged, the second clutch CL2 is slip-controlled as a transmission torque capacity TCL2 corresponding to the required driving force, and travels using the driving force of the engine E and / or motor generator MG. .

  In the hybrid vehicle of the first embodiment, there is no element that absorbs the difference in rotational speed unlike the torque converter. Therefore, when the first clutch CL1 and the second clutch CL2 are completely engaged, the vehicle speed is determined according to the rotational speed of the engine E. End up. The engine E has a lower limit value based on the idling engine speed for maintaining the self-sustaining rotation, and the idling engine speed further increases when the engine is idling up due to warm-up operation of the engine. In addition, when the required driving force is high, there may be a case where the HEV traveling mode cannot be quickly changed.

  On the other hand, in the EV travel mode, since the first clutch CL1 is released, there is no limit associated with the lower limit value due to the engine speed. However, in the case where it is difficult to travel in the EV travel mode due to restrictions based on the battery SOC, or in a region where the required driving force cannot be achieved only by the motor generator MG, there is no means other than generating stable torque by the engine E.

  Therefore, when the vehicle speed range is lower than the vehicle speed corresponding to the lower limit value and it is difficult to travel in the EV travel mode, or when the required driving force cannot be achieved only by the motor generator MG, the engine speed is set to the predetermined rotational speed. The WSC traveling mode is selected in which the second clutch CL2 is slip controlled and the engine torque is used for traveling.

  FIG. 6 is a schematic diagram showing the engine operating point setting process in the WSC running mode, and FIG. 7 is a map showing the engine target speed in the WSC running mode.

  When the driver operates the accelerator pedal in the WSC travel mode, a target engine speed characteristic corresponding to the accelerator pedal opening APO is selected based on FIG. 7, and the target engine speed corresponding to the vehicle speed is determined along this characteristic. Is set. When the target engine speed characteristic corresponding to the accelerator pedal opening APO is selected, the target engagement rotational speed of the second clutch CL2 corresponding to each opening is also set. This target engagement rotational speed is a value corresponding to the boundary line between the WSC traveling mode region and the HEV traveling mode region shown in FIG. Then, the target engine torque corresponding to the target engine speed is calculated by the engine operating point setting process shown in FIG.

  Here, the operating point of the engine E is defined as a point defined by the engine speed and the engine torque. As shown in FIG. 6, it is desirable that the engine operating point is operated on a line (hereinafter referred to as “α line”) connecting operating points with high output efficiency of the engine E.

  However, when the engine speed is set as described above, an operating point away from the α line is selected depending on the driver's accelerator pedal operation amount (required driving force). Therefore, in order to bring the engine operating point closer to the α line, the target engine torque is feedforward controlled to a value that takes the α line into consideration.

  On the other hand, the motor generator MG executes the rotational speed feedback control using the set engine rotational speed as the target rotational speed. Since the engine E and the motor generator MG are now in a directly connected state by engaging the first clutch CL1, the motor generator MG is controlled so as to maintain the target rotational speed, so that the rotational speed of the engine E is also automatic. Feedback control is performed.

  At this time, the torque output from motor generator MG is automatically controlled so as to fill the deviation between the target engine torque determined in consideration of the α-ray and the required driving force. In the motor generator MG, a basic torque control amount (regeneration / power running) is given so as to fill the deviation, and further feedback control is performed so as to match the target engine speed.

  When the required driving force is smaller than the driving force on the α line at a certain engine speed, the engine output efficiency increases as the engine output torque is increased. At this time, the motor generator MG recovers the energy corresponding to the increased output, and the torque input to the second clutch CL2 becomes the torque required by the driver, and efficient power generation is possible.

  However, since the upper limit of torque that can be generated is determined according to the state of the battery SOC, the required power generation output (SOC required power generation power) from the battery SOC and the deviation between the torque at the current operating point and the torque on the α line (α It is necessary to consider the magnitude relationship with the (line generated power).

  FIG. 6A is a schematic diagram when the α-ray generated power is larger than the SOC required generated power. Since the engine output torque cannot be increased above the SOC required power generation, the operating point cannot be moved on the α line. However, fuel efficiency is improved by moving to a more efficient point.

  FIG. 6B is a schematic diagram when the α-ray generated power is smaller than the SOC required generated power. Since the engine operating point can be moved on the α line within the SOC required power generation range, in this case, it is possible to generate power while maintaining the operating point with the highest fuel efficiency.

  FIG. 6C is a schematic diagram when the engine operating point is higher than the α line. When the operating point corresponding to the required driving force is higher than the α line, the engine torque is reduced on the condition that the battery SOC has a margin, and the shortage is compensated by the power running of the motor generator MG. As a result, the required driving force can be achieved while improving the fuel efficiency.

[Control processing at start-up]
Next, the starting control process will be described. As described above, when the WSC traveling mode starts on a flat road, as shown in FIG. 7, the target engine speed for each vehicle speed corresponding to the accelerator pedal opening APO is set on the map. When the target engine speed is set, torque corresponding to the driver request torque is output from engine E and motor generator MG. The engagement torque capacity of the second clutch CL2 is set according to the accelerator pedal opening APO.

  With these preset relationships, a desired slip state in the second clutch CL2 is achieved. This slip state is set so that the input / output rotational speed of the second clutch CL2 matches when the engine rotational speed, which is the input rotational speed of the second clutch CL2, reaches the target engagement rotational speed.

  Here, the problem in the inertia fluctuation of the drive wheel will be described. FIG. 9 is a time chart during start control. In FIG. 9, the second clutch output speed Ncl2out when starting control on a flat road is indicated by a thick solid line, and the second starting point when performing the same starting control as that on a flat road on a downward slope road (hereinafter referred to as a comparative example). The clutch output speed Ncl2out is indicated by a dotted line. The engine speed is defined by the map shown in FIG. 7, and follows the same locus on both the flat road and the comparative example.

  When the driver depresses the accelerator pedal from when the vehicle is stopped, torque corresponding to the driver's request is output from the engine E and the motor generator MG, and the engine speed starts to rise along the target speed. Since the second clutch CL2 is set to the target second engagement torque capacity, the output rotation speed Ncl2out of the second clutch CL2 also starts to increase.

  Here, in the case of the comparative example, the vehicle inertia for rotating the drive wheels is small because it is a downhill road of the vehicle, and accordingly, the output side rotational speed Ncl2out of the second clutch CL2 increases rapidly, and the engine rotation When the number is lower than the target engine speed, the slip state is shifted to the complete engagement state. Therefore, there is a problem that the output side rotational speed Ncl2out change rate of the second clutch CL2 is too large compared with the engine rotational speed change rate, resulting in a fastening shock at the time of fastening.

  Therefore, it is conceivable that the engine speed is further increased to maintain the slip state until both the engine speed and the output speed Ncl2out reach the target engagement speed. In order to increase the engine speed, it is necessary to increase the engine torque or the motor generator torque.

  However, for example, when starting with the accelerator fully open, the engine torque and motor generator torque may be at their maximum values. If a larger torque cannot be output, the target engagement speed will still be reached. There is a problem that the slip state cannot be maintained until it reaches.

  Therefore, in the first embodiment, the above-described problem is solved by performing a correction that reduces the engagement torque capacity of the second clutch CL2. Hereinafter, the reason why the engagement torque capacity of the second clutch CL2 is reduced will be described.

The equation of motion at the time of slip control of the second clutch CL2 is expressed as follows.
(Formula 1)
Tin−Tcl2 ＝ Iin × dωin / dt
(Formula 2)
Tcl2-Tr = Iout × dωout / dt
Here, Tin is the input torque to the second clutch CL2, Tcl2 is the engagement torque capacity of the second clutch CL2, Iin is the inertia on the input side of the second clutch CL2, and dωin / dt is the rotation on the input side of the second clutch CL2. Angular acceleration, Tr is running resistance, Iout is vehicle inertia, and dωout / dt is rotational angular acceleration on the output side of the second clutch CL2.

  On a downhill road, this is synonymous with a decrease in Iout in the above equation. When Tcl2 is the same, dωout / dt increases in Equation 2 when Iout decreases, causing the above-described problem.

  Therefore, when Tcl2 is decreased, in Equation 2, an increase in dωout / dt is suppressed by the amount of decrease in Iout. At the same time, in Equation 1, dωin / dt increases as Tcl2 decreases. That is, it is possible to suppress the increase in the output rotational speed Ncl2out while appropriately increasing the engine rotational speed, and it is possible to maintain the slip state.

FIG. 8 is a flowchart showing the start control process on the downhill road.
In step S1, it is determined whether or not the road gradient estimated by the downhill determination unit 202 is equal to or less than a first predetermined value. If the road gradient is equal to or less than the predetermined value, it is determined as a downward gradient road and the process proceeds to step S2. Advances to step S7.

  In step S2, the input side rotational speed change rate dωin / dt (for example, the engine rotational speed change rate) of the second clutch CL2 and the output side rotational speed change rate dωout / dt (for example, the automatic transmission AT to the vehicle speed). Value taking into account the gear ratio).

  In step S3, the estimated engagement rotational speed α is calculated. Here, the estimated engagement rotational speed α means a rotational speed at which both rotational speeds coincide with each other on the assumption that the current input-side rotational speed and the current output-side rotational speed are changed at respective change rates.

  In step S4, the target second clutch engagement torque capacity correction unit 203 determines whether or not the estimated engagement rotation speed α is smaller than the target engagement rotation speed. If it is smaller, the process proceeds to step S6 and the target second clutch engagement torque. Subtract a predetermined amount from the capacity. On the other hand, when the estimated engagement rotation speed α is equal to or higher than the target engagement rotation speed, the process proceeds to step S5, and a target second clutch engagement torque capacity is added by a predetermined amount.

  In step S7, it is determined whether or not the road surface gradient is greater than or equal to a second predetermined value greater than the first predetermined value. If the road surface gradient is greater than or equal to the predetermined value, it is determined that the road is an uphill road and the process proceeds to step S5. Is added by a predetermined amount.

  Next, the operation based on the flowchart will be described with reference to FIG. FIG. 9 is a time chart during start control. In FIG. 9, the second clutch output rotational speed Ncl2out when starting control on a downhill road is indicated by a thick dashed line, and the engine rotational speed at this time is indicated by a thin dashed line.

  When the driver depresses the accelerator pedal on a downhill slope at time t1, a target engine speed characteristic corresponding to the accelerator pedal opening APO is selected and a target second engagement torque capacity is set. When the target engine speed characteristic is determined, the target engagement speed is determined, and the engine E and the motor generator MG output the required torque based on the relationship shown in FIG. At this time, the estimated engagement rotation speed α is calculated at the same time, and the target second engagement torque capacity is not particularly corrected while the estimated engagement rotation speed α substantially matches the target engagement rotation speed.

  At time t2, since it is a downward slope road, the output side rotational speed change rate dωout / dt of the second clutch CL2 increases due to a decrease in inertia for rotating the driving wheel, and the estimated engagement rotational speed α is higher than the target engagement rotational speed. Is also reduced, the target second engagement torque capacity is corrected to be small. As a result, the engine E on the input side of the second clutch CL2 continues to output torque corresponding to the rotational speed set by the target rotational speed characteristic, so that the engine load decreases and the engine rotational speed increases.

  At the same time, since the torque transmitted to the drive wheel on the output side of the second clutch CL2 is reduced, an increase in the output side rotational speed of the second clutch CL2 is suppressed. Then, the subtraction correction of the target second engagement torque capacity is repeated until the estimated engagement rotation speed α substantially matches the target engagement rotation speed.

  At time t3, when the engine speed, which is the input side speed of the second clutch CL2, and the output side speed of the second clutch CL2 match, the slip state is shifted to the fully engaged state. That is, unlike the comparative example, the engine is not completely fastened at a low engine speed, so that the slip state can be reliably maintained and the fastening shock is avoided.

  Although not shown in the time chart, the inertia for rotating the driving wheel is increased on the uphill road, and the increase in the output side rotational speed Ncl2out of the second clutch CL2 is delayed. In this case, complete engagement is performed at a higher rotation speed than the target engagement rotation speed, and the slip amount of the second clutch CL2 becomes excessive, and there is a concern about heat generation. Therefore, at this time, the heat generation of the second clutch CL2 is suppressed by adding the target second clutch engagement torque capacity to achieve complete engagement at the target engagement rotation speed.

As described above, the effects listed below can be obtained in the first embodiment.
(1) The second clutch CL2, a road surface gradient estimation calculation unit 201 as an inertia detection means for detecting or estimating the inertia of the drive wheel, and slip by applying a target second clutch engagement torque capacity to the second clutch CL2 at the start When the estimated road surface gradient is smaller than a predetermined value at the time of the transition from the engagement to the complete engagement in the WSC drive mode and from the WSC drive mode to the HEV drive mode, the target to reduce the target second clutch engagement torque capacity And a second clutch engagement torque capacity correction unit 203.

  Therefore, even if the inertia of the drive wheel is reduced, it is possible to suppress a sudden increase in the number of rotations on the drive wheel side of the second clutch CL2, and it is possible to suppress a fastening shock. Further, the heat generation of the second clutch CL2 can be suppressed by reducing the target engagement torque capacity of the second clutch CL2.

  (2) When the engagement torque capacity is reduced by the target second clutch engagement torque capacity correction unit 203, the rotational speeds of the engine E and the motor generator MG are increased by the torque corresponding to the decrease. In other words, if the engagement torque capacity of the second clutch CL2 is reduced without changing the torque of the engine E and the motor generator MG, the rotational speed of the engine E and the motor generator MG is used to increase its own rotational speed accordingly. Will be.

  Therefore, it is possible to increase the rotational speeds of the engine E and the motor generator MG without increasing the torque of the engine E and the motor generator MG, and the slip state of the second clutch CL2 can be ensured. In addition, the rotational speed can be increased even when the torques of the engine E and the motor generator MG output maximum values due to the accelerator fully open operation.

  (3) The target second clutch engagement torque capacity correcting unit 203 increases the target second clutch engagement torque capacity when the road surface gradient is larger than a second predetermined value larger than the predetermined value.

  Therefore, complete engagement at the target engagement rotation speed can be achieved, and heat generation of the second clutch CL2 can be suppressed.

  (4) As an inertia detection means, a means for detecting or estimating a road gradient is adopted. Therefore, it is possible to accurately grasp the inertia acting on the vehicle.

  (5) The inertia detection means may be a means for detecting or estimating a predetermined slip or more of the wheel. For example, when the road surface μ decreases and the driving wheel slips, the load acting on the driving wheel is reduced by the low μ even on a flat road, in other words, the inertia is small. Therefore, in this case as well, by reducing the target second clutch engagement torque capacity, it is possible to suppress a rapid increase in the number of rotations on the drive wheel side of the second clutch CL2, and it is possible to suppress the engagement shock.

  (6) Further, in the first embodiment, as shown in FIG. 7, the target engagement rotational speed is set so that the engine rotational speed that is the input side rotational speed of the second clutch CL2 and the output side rotational speed Ncl2out coincide. Then, the target second clutch engagement torque capacity of the second clutch CL2 is controlled so that the engine rotation speed and the output side rotation speed Ncl2out coincide with each other at the target engagement rotation speed at the time of start.

  Thus, the engagement shock can be suppressed until the slip state of the second clutch CL2 is ensured until the target engagement rotational speed is reached. On the other hand, the second clutch CL2 can be prevented from generating heat without being completely engaged at a rotational speed greater than the target engagement rotational speed.

  (7) In the first embodiment, the rotational speeds ωin, ωout and rotational angular accelerations dωin / dt and dωout / dt, which are rotational speed change rates, are detected in step S2 on the input side and the output side of the second clutch CL2. In step S3, an estimated engagement rotational speed α at which the input side rotational speed ωin matches the output side rotational speed ωout is calculated based on this rotational information. When the estimated engagement rotational speed α is smaller than the target engagement rotational speed, the target second clutch engagement torque capacity is reduced.

  Therefore, in addition to the suppression of the fastening shock, the heat generation of the second clutch CL2 can be suppressed.

  (8) In the first embodiment, when the estimated engagement rotation speed α is larger than the target engagement rotation speed, the target second clutch engagement torque capacity is increased.

  Therefore, in addition to suppressing the heat generation of the second clutch CL2, a driving force corresponding to the road surface gradient can be obtained.

  (9) Further, the engine E and the motor generator MG are used as power sources.

  Therefore, even when a high driving torque is required at a low rotation, it is possible to ensure the torque of the power source and suppress engine stall or the like.

  As described above, the description has been given based on the first embodiment. However, the present invention is not limited to the above-described configuration, and other configurations can be taken without departing from the scope of the present invention.

  For example, in the first embodiment, the present invention is applied to a hybrid vehicle, but the vehicle does not include a motor generator or the like and does not include a torque converter, and the vehicle starts by engagement control such as a start clutch. If applicable, it is equally applicable.

  In the first embodiment, the target engagement rotational speed is set and controlled to smoothly shift to complete engagement at the rotational speed. However, the engagement capacity of the second clutch CL2 is simply added or subtracted according to the inertia of the road surface gradient or the like. It is good also as composition to do. In the first embodiment, the basic target second clutch engagement torque capacity calculation value is corrected. However, the present invention is not limited to the correction, and a value such as a road surface gradient may be introduced into the target value calculation logic. .

  Further, in the first embodiment, the road surface gradient is detected or estimated as the inertia, but the presence / absence of vehicle traction or the like may be detected, or the in-vehicle load may be detected.

  Further, although the temperature sensor 10a is provided as means for detecting the temperature of the second clutch CL2, the heat generation amount may be estimated based on the differential rotation of the second clutch CL2 and the transmission torque capacity TCL2.

  In the first embodiment, the FR type hybrid vehicle has been described. However, an FF type hybrid vehicle may be used.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall system diagram illustrating a rear-wheel drive hybrid vehicle according to a first embodiment. FIG. 3 is a control block diagram illustrating an arithmetic processing program in the integrated controller according to the first embodiment. It is a figure which shows an example of the target driving force map used for target driving force calculation in the target driving force calculating part of FIG. It is a figure which shows an example of the target charging / discharging amount map used for the calculation of target charging / discharging electric power in the target charging / discharging calculating part of FIG. It is a figure which shows the normal mode map used for selection of the target mode in the mode selection part of FIG. It is the schematic showing the engine operating point setting process in WSC driving mode. It is a map showing the engine target speed in WSC driving mode. 3 is a flowchart illustrating a start control process according to the first embodiment. 3 is a time chart during start control according to the first embodiment.

Explanation of symbols

E engine
CL1 1st clutch
MG motor generator
CL2 2nd clutch
AT automatic transmission 1 engine controller 2 motor controller 3 inverter 4 battery 5 first clutch controller 6 first clutch hydraulic unit 7 AT controller 8 second clutch hydraulic unit 9 brake controller 10 integrated controller 24 brake hydraulic sensor
100 Target driving force calculator
200 Mode selection section
300 Target charge / discharge calculator
400 Operating point command section

Claims (9)

A fastening element that is interposed between a power source and a drive wheel and connects and disconnects the power source and the drive wheel;
Inertia detection means for detecting or estimating the inertia of the drive wheel;
Start control means for applying a predetermined fastening torque capacity to the fastening element at the time of start and shifting from slip fastening to full fastening;
At the time of transition by the start control means, when the inertia is smaller than a predetermined value, correction means for reducing the predetermined fastening torque capacity;
A vehicle start control device comprising: In the vehicle start control device according to claim 1,
When the fastening torque capacity is reduced by the correcting means, the vehicle start control device increases the rotational speed of the power source by a torque corresponding to the reduced amount. In the vehicle start control device according to claim 1 or 2,
The correction means increases the predetermined fastening torque capacity when the inertia is larger than a second predetermined value larger than the predetermined value at the time of transition by the start control means. Start control device. In the vehicle start control device according to any one of claims 1 to 3,
The vehicle start control device, wherein the inertia detection means is means for detecting or estimating a road surface gradient. In the vehicle start control device according to any one of claims 1 to 4,
The vehicle start control device according to claim 1, wherein the inertia detection means is means for detecting or estimating a predetermined slip or more of a wheel. An input element interposed between the power source and the drive wheel and connected to the power source;
An output element connected to the drive wheel;
A fastening element for connecting and disconnecting the input element and the output element;
Target fastening rotational speed setting means for setting a target fastening rotational speed of the fastening element for matching the rotational speed of the input element and the rotational speed of the output element;
Start control means for controlling the fastening torque capacity of the fastening element so that the rotational speed of the input element and the rotational speed of the output element coincide with each other at the target fastening rotational speed at the time of start;
A vehicle start control device comprising: In the vehicle start control device according to claim 6,
Rotation information detection means for detecting rotation information which is the rotation speed and rotation speed change rate of the input element and the output element;
Estimated fastening rotational speed calculation means for calculating an estimated fastening rotational speed at which the rotational speeds of the input element and the output element match based on the rotational information is provided;
The vehicle start control device, wherein the start control means reduces the fastening torque capacity when the estimated fastening rotational speed is smaller than the target fastening rotational speed. The vehicle start control device according to claim 7,
The vehicle start control device, wherein the start control means increases the fastening torque capacity when the estimated fastening rotational speed is larger than the target fastening rotational speed. In the vehicle start control device according to any one of claims 1 to 6,
The start control apparatus for a vehicle, wherein the power source is an engine and a motor.

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