JP2008120361A - Control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for a vehicle, controlling a fastening element equipped between a driving force source and driving wheels under very low temperature without giving an uncomfortable feeling to a driver. <P>SOLUTION: This control device for the vehicle has: the driving force source; the fastening element interposed between the driving force source and the driving wheels; and an electronic control brake automatically imparting braking force to the wheels. The control device also has: a fastening torque control means controlling fastening torque of the fastening element; and a super-low-temperature control means outputting an instruction to the electronic control brake to impart prescribed braking force to the wheels when controlling the fastening torque of the fastening element at very low temperature. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control device including a fastening element between a driving force source and driving wheels.

The technique of Patent Document 1 is disclosed as a vehicle control device including a fastening element between a driving force source and a driving wheel. This vehicle is a hybrid vehicle including an engine and a motor as a driving force source, and includes a first fastening element (Ci clutch) that connects and disconnects the engine and the motor, and a second fastening element that connects and disconnects the motor and the drive wheels. (Input clutch).
Japanese Patent Laid-Open No. 11-82261

  In the hybrid vehicle described in Patent Document 1, since the wet clutch is used as the input clutch, the viscosity resistance of the oil filled between the friction plates increases in a cryogenic environment, and the drag torque of the input clutch increases. It will increase. For this reason, the controllability of the input clutch that transmits torque from the driving force source (motor) to the driving wheels is lowered, and the output torque to the driving wheels may fluctuate, which may cause the driver to feel uncomfortable.

  The present invention has been made paying attention to the above-described problem, and even when the fastening element provided between the driving force source and the driving wheel is controlled at an extremely low temperature, the driver feels uncomfortable. An object of the present invention is to provide a control device for a vehicle that can be controlled without any problems.

  To achieve the above object, in the vehicle control apparatus of the present invention, a driving force source, a fastening element interposed between the driving force source and the driving wheel, and a braking force are automatically applied to the wheel. An electronic control brake comprising: a fastening torque control means for controlling a fastening torque of the fastening element; and a command to the electronic control brake when controlling the fastening torque of the fastening element at an extremely low temperature. And a control means at cryogenic temperature for applying a predetermined braking force to the wheel.

  Therefore, in the vehicle control apparatus of the present invention, it is possible to prevent the output torque to the drive wheels from fluctuating due to the drag torque of the fastening element, and to prevent the driver from feeling uncomfortable.

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

  First, the drive system configuration of the vehicle according to the first embodiment will be described. FIG. 1 is an overall system diagram showing a rear-wheel drive hybrid vehicle to which a control device of the present invention is applied. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a flywheel FW, a first clutch CL1, a motor generator MG, a second clutch CL2, an automatic transmission AT, It has a propeller shaft PS, 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). Note that FL is the left front wheel and FR is the right front wheel.

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

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

  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”). 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 (corresponding to the engagement element described in the claims) is an engagement element interposed between the motor generator MG and the left and right rear wheels RL, RR, and is controlled by the AT controller 7 described later. Based on the command, the engagement / release including slip engagement and slip release is controlled by the control oil pressure generated by the second clutch hydraulic unit 8. The first clutch CL1 and the second clutch CL2 are clutches that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid. Specifically, the second clutch CL2 is a wet multi-plate clutch that includes a plurality of friction plates immersed in AT hydraulic fluid and generates a fastening capacity by the frictional force between the plurality of friction plates. If lubricating oil is supplied between the friction plates, it is assumed that the above is “immersed in AT hydraulic fluid”.

  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 of the fastening elements that are fastened at each speed of the automatic transmission AT are used.

  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.

  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 engine-use slip travel mode (hereinafter referred to as “WSC (Wet Start Clutch) 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. For short). The WSC traveling mode is selected when the battery SOC is insufficient and it is necessary to start with only the power of the engine E.

  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 to each other via a CAN communication line 11 that can exchange information. ing.

  The engine controller 1 inputs the engine speed information from the engine speed sensor 12, and in response to a target engine torque command or the like from the integrated controller 10, a command for controlling the engine operating point (Ne, Te), for example, Output to the outside throttle valve actuator. The engine controller 1 is provided with an engine torque estimation unit 1a that estimates the engine torque Te based on the fuel injection amount of the engine E, the throttle opening, and the like. Information on the engine speed Ne and the estimated engine torque Te 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 rotation position of the motor generator MG, and the motor operating point (Nm, Tm) of the motor generator MG in accordance with a target motor generator torque command or the like from the integrated controller 10. 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 for control information of the motor generator MG and is supplied to the integrated controller 10 via the CAN communication line 11. To do.

  In addition, a motor generator torque estimation unit 2a that estimates the motor generator torque Tm based on the value of the current flowing through the motor generator MG (the driving torque and the regenerative torque are distinguished based on whether the current value is positive or negative) is provided. Information on the estimated motor generator torque Tm is supplied to the integrated controller 10 via the CAN communication line 11.

  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 the AT oil temperature sensor 7 a, and in response to the second clutch control command from the integrated controller 10, A command for controlling engagement / disengagement of the two clutch CL2 is output to the second clutch hydraulic unit 8 in the AT hydraulic control valve. Information on the accelerator pedal opening APO, the vehicle speed VSP, and the AT oil temperature 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 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 (hydraulic braking force or motor braking force).

  In the first embodiment, the brake control is executed by BBB (brake by wire). Here, BBW is an electronic control that does not have any mechanical linkage between the brake pedal and the master cylinder, electrically detects an operation (brake stroke) on the brake pedal, and generates a braking force based on the detected value. It is a brake. Each wheel RL, RR, FL, FR is provided with a brake unit BURL, BURR, BUFL, BUFR. The brake units BURL, BURR, BUFL, and BUFR generate desired hydraulic braking forces on the wheels RL, RR, FL, and FR based on control commands from the brake controller 9, respectively.

  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. Information from the second clutch output rotational speed sensor 22 for detecting the second clutch torque sensor 23 for detecting the second clutch torque TCL2 and the brake hydraulic pressure sensor 24 and information obtained via the CAN communication line 11 Enter.

  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 calculates a target mode from the accelerator pedal opening APO and the vehicle speed VSP using the EV-HEV selection map shown in FIG. However, if the battery SOC is equal to or less than the predetermined value, the “HEV travel mode” is forcibly set as the target mode. The HEV → WSC switching line or EV → WSC switching line is set in a region lower than the vehicle speed VSP1 at which the rotational speed is smaller than the idle rotational speed of the engine E when the automatic transmission AT is in the first gear. A hatched area in FIG. 4 is an area where the HEV traveling mode is switched to the WSC traveling mode, and a shaded area in FIG. 4 is an area where the WSC traveling mode is switched to the EV traveling mode.

  Target charge / discharge calculation section 300 calculates target charge / discharge power tP from battery SOC using a predetermined target charge / discharge amount map.

  As shown in FIG. 2, the operating point command unit 400 includes a target fastening torque calculation unit 401, a fastening torque control unit 402, a motor rotation speed control unit 403, a motor torque control unit 404, a fastening torque estimation unit 405, , And a switching unit 406.

  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 charge / discharge power tP as target operating point reaching torques as the target second clutch engagement torque. And a target automatic shift shift, a first clutch solenoid current command, and a transient target engine torque Te * are calculated. The target engine torque Te * is output to the engine controller 1 to control the operation of the engine E. Further, the target motor rotational speed Nm * and the target motor torque Tm * are calculated based on the target driving force tFoO and the like, and these are output to the motor controller 2 to control the operation of the motor generator MG. That is, motor speed control and motor torque control are performed.

  Specifically, the motor rotation speed control unit 403 controls the target motor rotation speed Nm * so that the input rotation speed on the motor generator MG side is higher than the output rotation speed on the drive wheel side of the second clutch CL2. Further, the motor torque control unit 404 controls the target motor torque Tm * based on the target driving force tFoO.

  Further, the switching unit 406 performs control by the motor rotational speed control unit 403 and control by the motor torque control unit 404 based on a second clutch engagement torque target value TCL2 * described later and an estimated second clutch engagement torque TCL2. Switch.

  In addition, the operating point command unit 400 is provided with an engine start control unit 410 that starts the engine E based on an engine start request at the time of transition from the EV travel mode to the HEV travel mode.

  Here, engine start control will be described. When the engine start request is made, the engagement capacity of the second clutch CL2 is set to the engagement capacity that becomes the output torque before the engine start (the output shaft torque on the driving wheels RR, RL side of the second clutch CL2), Increase driving force of motor generator MG. Then, since the load acting on motor generator MG is only the engagement capacity of second clutch CL2, motor generator MG may over-rotate due to excessive driving force. Therefore, the rotational speed control of motor generator MG is executed as will be described later. Since the output torque is determined by the engagement capacity of the second clutch CL2, the output torque does not vary as long as the second clutch CL2 slips.

  After the engine start request, the engagement capacity of the first clutch CL1 is increased to a predetermined value so that the engine can be started as quickly as possible at the timing when the driving force of the motor generator MG is expected to have sufficiently increased.

  When the engagement capacity of first clutch CL1 increases to a predetermined value, the load acting on motor generator MG increases, and torque Tm of motor generator MG also increases as the engagement capacity of first clutch CL1 increases. At this time, since the engagement capacity of the first clutch CL1 is increased to an engagement capacity of about the torque required for starting the engine E, the cranking of the engine E is performed and the engine E starts to rotate independently. Startup is complete.

  As described above, during the engine start control, the second clutch CL2 is continuously put into the slip state, and the fluctuation of the output torque is suppressed as much as possible.

  The shift control unit 500 drives and controls the solenoid valve in the automatic transmission AT so as to achieve the target shift speed and the target engagement torque of each clutch according to a preset shift schedule. In this shift schedule, a target gear stage is set in advance based on the vehicle speed VSP and the accelerator pedal opening APO, and an upshift line, a downshift line, and the like are set.

  The engagement torque target value calculation unit 401 calculates the second clutch engagement torque target value TCL2 * based on the target driving force tFoO and outputs it to the engagement torque control unit 402 and the switching unit 406. The engagement torque control unit 402 outputs the second clutch engagement torque target value TCL2 * to the shift control unit 500, and performs control so that the engagement torque of the second clutch CL2 becomes the target value TCL2 *. The engagement torque estimation unit 405 estimates the engagement torque TCL2 of the second clutch CL2 based on the estimated motor torque Tm, the motor rotation speed Nm, and the like, and outputs it to the switching unit 406.

(Slip control of the second clutch CL2)
When traveling at a certain vehicle speed, it is most efficient to fully engage the second clutch CL2, control the torque of the motor generator MG and the engine E, and control the torque of the drive wheels.

  On the other hand, when the vehicle starts, the motor generator rotational speed gradually increases from the state where the drive wheels are stopped. At this time, if the engine E is stopped and the first clutch CL1 is released, it is possible to start only by the driving force of the motor generator MG with the second clutch CL2 fully engaged.

  However, when the vehicle starts as described above, the motor generator MG becomes less efficient because it outputs extremely low rotation and high torque, which is not preferable. In addition, considering the case where a request for starting engine E is made and torque is required for engine cranking, it is necessary to allow some margin for the upper limit value of motor generator torque Tm. There are times when sufficient starting performance cannot be ensured. Further, when the engine E is being driven, it is necessary to ensure the idling speed of the engine E, and if the second clutch CL2 is completely engaged, there is a possibility of causing an engine stall.

  Furthermore, when starting with only the motor generator MG, a greater driving force may be required during the start and an engine start request may be made. In order to meet this request, the first clutch CL1 is engaged and the engine clutch is engaged. Ranking will be executed. At this time, a large load is suddenly applied to the motor generator MG, and the motor generator rotational speed may be reduced at a stretch, which may cause fluctuations in driving wheel speed and driving torque.

  Therefore, at the time of starting or starting the engine, the second clutch CL2 controls the fastening torque so as to achieve the target driving force, and maintains the slip state (slip control). At this time, the motor generator MG can cope with various scenes by independently controlling control such as engine start while achieving the target driving force.

(Second clutch control flowchart)
As described above, the second clutch CL2 is slip-controlled when starting or when starting the engine. When a predetermined condition is satisfied, the slip control is shifted to complete fastening, and the motor rotation speed control is switched to the motor torque control.

  FIG. 5 is a flowchart showing the engagement torque control process of the second clutch CL2.

  In step S1, it is determined whether a start request or an engine start request is made on the assumption that the second clutch CL2 is completely engaged. When this condition is satisfied, the process proceeds to step S2, and otherwise, the present control flow ends.

  In step S2, the second clutch engagement torque target value TCL2 * is calculated based on the target driving force tFoO, and the second clutch engagement torque control is executed so that the second clutch engagement torque TCL2 becomes the target value TCL2 *. The second clutch actual engagement torque TCL2 used for the second clutch engagement torque control uses the engagement torque TCL2 estimated in step S4 described later.

  The reason for executing the second clutch engagement torque control in this way is that if the engagement torque TCL2 of the second clutch CL2 is controlled, no matter how the torque on the input side (engine E or motor generator MG) fluctuates. This is because a torque higher than the second clutch engagement torque CL2 is not output to the drive wheel side, and stable traveling can be achieved.

  In step S3, motor rotation speed control is executed so that the rotation speed on the motor generator MG side is slightly higher than the rotation speed N2out on the drive wheel side of the second clutch CL2. Thereby, motor generator MG does not rotate excessively, and a decrease in durability of second clutch CL2 can be suppressed.

  In the motor rotation speed control, the rotation speed N2out is read, and a value obtained by adding a predetermined slip amount γ to the rotation speed N2out is set as a target rotation speed on the motor generator side of the second clutch CL2. Then, in order to achieve this target rotational speed, a target motor rotational speed Nm * taking into account a predetermined gear ratio and the like is set, and the motor generator MG is controlled so as to maintain this rotational speed Nm *. Therefore, a command value to motor generator MG is output based on a deviation between the target rotational speed and the actual rotational speed.

  At this time, how much torque is generated in motor generator MG is not a final control target. Therefore, the motor torque estimation unit 2b estimates the motor torque Tm based on the value of the current flowing through the motor generator MG, and transmits the estimated motor torque Tm to the integrated controller 10.

  In this way, by using the motor generator MG as the rotational speed control and the second clutch CL2 as the engagement torque control, a value corresponding to the engagement torque of the second clutch CL2 is reliably output to the drive wheels. This is because the motor torque Tm higher than the target drive force tFoO and the second clutch engagement torque TCL2 is automatically set in order to maintain the motor rotation speed Nm higher than the rotation speed N2out on the drive wheel side of the second clutch CL2. This is because that.

  In step S4, the actual engagement torque TCL2 of the second clutch CL2 is estimated based on the motor rotation speed Nm or the like and the detected engagement state of the first clutch CL1.

  In step S5, it is determined whether or not the estimated engagement torque TCL2 of the second clutch CL2 is within a predetermined range in consideration of the error a with respect to the target driving force tFoO. If it is within the predetermined range, the process proceeds to step S6. In other cases, Steps S2 to S5 are repeated until the fastening torque TCL2 falls within a predetermined range.

  In step S6, as the motor rotation speed control, the motor rotation speed Nm is controlled so that the predetermined slip amount γ becomes zero.

  The motor generator MG outputs a higher torque Tm in order to ensure the predetermined slip amount γ, and naturally the rotational speed on the input side of the second clutch CL2 is higher than the rotational speed N2out on the output side. If the second clutch CL2 is completely engaged in this state, the inertia torque on the input side of the second clutch CL2 is output to the drive wheel side, resulting in fluctuations in output torque, which may cause the driver to feel uncomfortable. is there. Further, if the engagement torque TCL2 of the second clutch CL2 is simply increased while the motor rotation speed control is being performed, the motor generator MG outputs a large drive torque Tm to ensure the slip amount γ.

  Therefore, the slip amount of the second clutch CL2 is gradually decreased by controlling the motor rotation speed control so that the slip amount becomes zero and gradually decreasing the motor torque Tm.

  In step S7, it is determined whether or not the slip amount of the second clutch CL2 is less than a predetermined value β representing an allowable range in which the torque fluctuation when fully engaged is considered to be small. When the slip amount is less than the predetermined value β, the process proceeds to step S8. In other cases, control returns to step S6 so that the slip amount becomes small.

  In step S8, the motor speed control is switched to the motor torque control.

  In step S9, the second clutch CL2 is completely engaged.

(Control processing at extremely low temperatures)
Next, the extremely low temperature control process of the present invention will be described.

  While the vehicle is running (including when starting), as described above, the engagement capacity of the second clutch CL2 may be set to a predetermined value and slip control may be executed. However, at a very low temperature, there is a case in which the drag torque of the second clutch CL2 is generated due to an increase in the viscous resistance of the oil filled between the friction plates. In this case, the second clutch CL2 is in a completely engaged state. There is a risk that the slip will not start and the clutch will not shift to the half-clutch state. In this case, since the increased driving force of the motor generator MG is output as it is to the output side of the second clutch CL2, that is, the driving wheels RR and RL, the vehicle acceleration that is larger than the target is caused and the driver feels uncomfortable. There is a fear.

  Therefore, when slip control of the second clutch CL2 is executed while the vehicle is running, trigger control is performed to shift the second clutch CL2 to the half-clutch state, and braking control is performed to prevent fluctuations in the output torque. Execute.

  On the other hand, when the vehicle is stopped, the engine may be started in preparation for starting (WSC traveling mode). At this time, the engine E is started with the second clutch released. However, when the temperature is extremely low, drag torque of the second clutch is generated, and the driving force of the engine E may be output to the output side of the second clutch, that is, the drive wheels RR and RL by the drag torque. This may cause unintended output torque fluctuations and give the driver a feeling of strangeness.

  Therefore, when the engine is started at a very low temperature while the vehicle is stopped, the braking control for preventing the fluctuation of the output torque is executed. This will be specifically described below.

  The integrated controller 10 has a cryogenic temperature control unit 600. As shown in FIG. 6, the cryogenic temperature control unit 600 includes a cryogenic temperature determination unit 601, a vehicle speed detection unit 602, an engine start request detection unit 603, a start request detection unit 604, and a half clutch request detection unit 605. , A half-clutch trigger making control unit 606, a differential rotation detection unit 607, and a brake control command unit 608.

  FIG. 7 is a flowchart showing a cryogenic temperature control process executed by the cryogenic temperature controller 600.

In step S11, it is determined whether or not it is in an extremely low temperature state. When it is in an extremely low temperature state, the process proceeds to step S12, and otherwise, this control flow is terminated.
Specifically, whether or not the oil temperature in the automatic transmission AT is within a predetermined range (for example, −40 to −20 ° C.) based on the detection result of the AT oil temperature sensor 7a. Judging.

In step S12, it is determined whether or not the vehicle is stopped. If it is stopped, the process proceeds to step S3. Otherwise, the process proceeds to step S17.
Specifically, the vehicle speed detection unit 602 determines whether or not the vehicle speed VSP is zero based on the detection results of the vehicle speed sensor 17 and the second clutch output rotation speed sensor 22.

(While the vehicle is stopped)
In step S13, engine start request detecting section 603 determines whether engine start is requested. If so, the process proceeds to step S14, and otherwise, the control flow ends.

In step S14, the brakes of each wheel are completely engaged by the brake control by BWB based on the command from the brake control command unit 608 so that the wheel does not move. Thereafter, the process proceeds to step S15.
Thereby, even if drag torque of the second clutch CL2 is generated at an extremely low temperature, unintended output torque fluctuations are prevented.

In step S15, it is determined whether a start request has been made. If a start request is made, the process proceeds to step S16, and otherwise, the control flow ends.
Specifically, the start request detection unit 604 determines that a start request has been made when it detects the establishment of a predetermined condition such as the release of the brake pedal and the depression of the accelerator pedal.

In step S16, in the brake control by BBB based on the command from the brake control command unit 608, complete engagement of the brake is released. Thereafter, this control flow is terminated.
After the vehicle speed VSP becomes greater than zero, half-clutch trigger making control and braking control, which will be described later, are performed in steps S17 to S20 of the next control cycle.

(Vehicle traveling)
In step S17, it is detected whether there is a half-clutch request for the second clutch CL2, that is, whether a slip control command is output. If the slip control command has been output, the process proceeds to step S18, and otherwise, the control flow ends.
Specifically, the half-clutch request detection unit 605 detects the presence / absence of a half-clutch request based on the detection results of the engine start request detection unit 603 and the start request detection unit 604. For example, it is determined whether an engine start request is made during traveling and the engagement capacity (engagement torque target value TCL2 *) of the second clutch CL2 is set to an engagement capacity that is an output torque before the engine is started.

In step S18, the trigger making control for realizing the half clutch state by slipping the second clutch CL2 is executed. Thereafter, the process proceeds to step S19.
Specifically, a command is output from the half-clutch trigger making control unit 606 to the AT controller 7, and the engagement hydraulic pressure (the pressing force of the second clutch) supplied to the second clutch CL2 by the second clutch hydraulic unit 8 is a predetermined amount or more. This is triggered by a decrease.

  Note that a slightly larger predetermined torque may be temporarily input to the input side (motor generator MG side) or output side (drive wheel side) of the second clutch CL2 to trigger the transition to the half-clutch state. For example, the trigger may be generated by outputting a command to the motor controller 9, increasing the motor generator torque Tm, and increasing the input torque to the second clutch CL2 above a predetermined torque. Here, the input torque is the torque on the input side of the second clutch CL2, and is a value that takes into account the engine torque Te, the motor generator torque Tm, and the engaged state of the first clutch CL1. At this time, fluctuations in the output torque are suppressed by a braking force described later (step S20) provided by the electronic control brake.

  In step S19, it is determined whether or not a differential rotation has occurred between the input rotational speed Nm and the output rotational speed N2out of the second clutch CL2, that is, whether or not the second clutch CL2 has slipped into a half-clutch state. To do. If no differential rotation has occurred, the process proceeds to step S20. Otherwise, this control flow ends.

  Specifically, the differential rotation detection unit 607 detects the output rotation speed N2out from the second clutch output rotation speed sensor 22. Further, based on the input rotation speed Nm and the gear ratio, the output rotation speed Ncalc when the second clutch CL2 is completely engaged is calculated. If the difference | N2out−Ncalc | between these rotational speeds is equal to or larger than a predetermined threshold value, it is determined that a differential rotation has occurred.

In step S20, the following brake control is executed based on a command from the brake control command unit 608. Thereafter, this control flow is terminated.
That is, the pulsed ON / OFF control hydraulic pressure is input to the brake units BURL and BUR of the drive wheels RL and RR. For this control, a control oil pressure used in the ABS control may be used.

  When the drag torque of the second clutch CL2 is large, the second clutch CL2 may not be able to make a transition to the half-clutch state only by the half-clutch trigger making control described above. May cause fluctuations. Accordingly, in the first embodiment, the hydraulic braking force of the drive wheels RL and RR is controlled, and a predetermined braking force that cancels the increase in output torque is applied to the drive wheels RL and RR. Thereby, an excessive increase in output torque is suppressed, and unintended vehicle acceleration is prevented.

  Here, the cycle of the pulsed control hydraulic pressure given to the brake units BURL and BUR is set to a sufficiently small cycle that does not cause a change in the inertia of the vehicle. For this reason, there is little possibility of affecting the vehicle behavior by generating the braking force.

  At the same time, this braking force is also used as a trigger for shifting to the half-clutch state. That is, when the pulsed ON / OFF control oil pressure is input to the brake units BURL and BUR, a large braking torque is temporarily input to the output side of the second clutch CL2. This braking torque is in the opposite direction to the driving torque Tm on the input side of the second clutch CL2. When the magnitude of these torque differences exceeds the sum of the static friction torque and the drag torque acting between the input side plate and the output side plate of the second clutch CL2, the slip of the second clutch CL2 is realized. The

  The reason for the control oil pressure to be in the same pulse form as ABS control is that accurate oil pressure control is often difficult at extremely low temperatures, but it is sufficient to reliably prevent the occurrence of vehicle acceleration that is larger than the target. It is. Therefore, by using an easy-to-use pulsed braking hydraulic pressure, an excessive output torque caused by the second clutch CL2 not shifting to the half-clutch state is suppressed, and at the same time, a trigger for shifting to the half-clutch state is created.

  Then, by repeating this control flow until the above-mentioned differential rotation occurs, the transition of the second clutch CL2 to the half-clutch state is realized.

  As described above, in the configuration of the first embodiment, the following effects can be obtained.

  (1) The vehicle control apparatus according to the first embodiment includes a driving force source (engine E and motor generator MG), and a first interposed between the driving force source (motor generator MG) and driving wheels RR and RL. In a vehicle control device comprising a two-clutch CL2 and an electronically controlled brake (brake controller 9, brake unit BU, etc.) that automatically applies braking force to the wheels FR, FL, RR, RL, the second clutch CL2 The fastening torque control means for controlling the fastening torque TCL2 (the fastening torque control unit 402, etc.) and the electronically controlled brake (brake controller 9, brake unit BU) when controlling the fastening torque TCL2 of the second clutch CL2 at extremely low temperatures Etc.) and a control unit 600 at the time of cryogenic temperature (brake control command unit 608, steps S14 and S20 in FIG. 7) that outputs a command to the wheel to give a predetermined braking force.

  Therefore, when slip control of the engaging element (second clutch CL2) is executed at an extremely low temperature, the driving torque Tm of the driving force source (motor generator MG) may be output to the driving wheels RR and RL without being reduced by the drag torque. Even if there is a braking force, a braking force that cancels out this excess output torque is applied to the wheels FR, FL, RR, and RL. Therefore, it is possible to suppress fluctuations in output torque that are not intended by the driver and to prevent the driver from feeling uncomfortable.

  (2) The second clutch CL2 is a wet multi-plate clutch that includes a plurality of friction plates immersed in hydraulic oil and generates a fastening capacity by the frictional force between the plurality of friction plates.

  Therefore, the effect of the above (1) can be obtained in the vehicle using the wet multi-plate clutch that easily generates drag torque due to the viscous resistance of the hydraulic oil at low temperatures.

  (3) When the vehicle speed VSP is not zero, the cryogenic temperature control unit 600 outputs a command to the motor controller 2 or the AT controller 7 before outputting a command to the electronically controlled brake (brake controller 9, brake unit BU, etc.). Thus, the half-clutch trigger making control unit 606 (step S18 in FIG. 7) for executing the first trigger making control for creating the half-clutch state of the engaging element (second clutch CL2) is provided.

  When making an engine start request during driving, such as when shifting from EV driving mode to HEV driving mode, or when starting the vehicle after starting the engine, execute the half-clutch trigger control. (Step S18) When the differential rotation occurs between the input side and the output side of the second clutch CL2, this control is terminated (Step S19). Thus, if slip of the second clutch CL2 can be realized without executing brake control, controllability of the second clutch CL2 can be improved, unnecessary brake control can be avoided, and fuel consumption can be improved.

  (4) The cryogenic temperature control unit 600 uses the predetermined braking force applied to the drive wheels RR and RL by the electronically controlled brake (brake controller 9, brake unit BU, etc.) to perform the half-clutch state of the second clutch CL2. It was decided to execute the second trigger creation control for creating

  If differential rotation does not occur even by the half-clutch trigger making control, a predetermined braking force is input to the output side of the engaging element (second clutch CL2) (steps S19 and S20). As a result, unintended output torque fluctuations are suppressed, and at the same time, this is used as a trigger for slipping the engagement element (second clutch CL2) by this braking force. That is, two actions and effects of suppressing fluctuations in output torque and creating a half-clutch trigger can be obtained simultaneously by one brake control operation.

  (5) The command to the electronically controlled brake (brake controller 9, brake unit BU, etc.) is a command to generate a pulsed braking force on the wheels FR, FL, RR, RL.

  While accurate hydraulic control is often difficult at extremely low temperatures, it is sufficient to reliably prevent unintended output torque fluctuations. Therefore, it is possible to effectively suppress an excessive output torque and at the same time create a trigger for shifting to the half-clutch state by using a pulsed braking hydraulic pressure that is easy to use. Here, by using the control hydraulic pressure of the ABS control, the control of the present invention can be easily executed without adding special control.

  (6) When the vehicle speed VSP is zero, the extremely low temperature control unit 600 outputs a complete engagement command to the electronically controlled brake (brake controller 9, brake unit BU, etc.).

  While the vehicle is stopped, the engine E may be started in preparation for starting (WSC traveling mode). At this time, by setting the brake to the fully engaged state, the vehicle can be reliably maintained in the stopped state even when the engine torque may be transmitted to the drive wheels RR and RL by the drag torque. Therefore, it is possible to suppress fluctuations in output torque that are not intended by the driver and to prevent the driver from feeling uncomfortable.

  The vehicle control apparatus according to the second embodiment does not have a torque converter, and is a vehicle that starts by transmitting engine torque to driving wheels while slip-controlling a starting clutch interposed between the engine and driving wheels. Applied.

  FIG. 8 is an overall system diagram illustrating a vehicle driven by rear wheels of the second embodiment. As shown in FIG. 6, the drive system of the vehicle in the second embodiment includes an engine E, a flywheel FW, a starting clutch CL2, an automatic transmission AT, a propeller shaft PS, a differential DF, and a left drive shaft DSL. And a right drive shaft DSR, a left rear wheel RL (drive wheel), and a right rear wheel RR (drive wheel).

  The starting clutch CL2 (corresponding to the engaging element described in the claims) is an engaging element interposed between the engine E and the left and right rear wheels RL, RR. Based on a control command from the clutch controller, engagement / release including slip engagement and slip release is controlled by a control hydraulic pressure generated by a start clutch hydraulic unit (not shown). As the starting clutch CL2, a wet multi-plate clutch capable of continuously controlling the oil flow rate and hydraulic pressure with a proportional solenoid is used. Specifically, the starting clutch CL2 includes a plurality of friction plates immersed in the hydraulic oil, and generates a fastening capacity by the frictional force between the plurality of friction plates.

  Other configurations of the drive system of the second embodiment and the configuration of the control system are the same as those of the first embodiment.

  In this type of vehicle, when starting the vehicle, start the engine E with the start clutch CL2 open, and then execute slip control that gradually increases the engagement capacity of the start clutch CL2, thereby engaging at the start Smooth start while preventing shock. For example, in a vehicle that executes idle stop control that stops the engine E when the vehicle is stopped, the slip control of the start clutch CL2 is executed when the engine E is restarted to start the vehicle.

  However, at extremely low temperatures, there are cases where drag torque of the start clutch CL2 is generated as in the first embodiment. Alternatively, the generated engagement torque may be larger than the command value even though the half-clutch state is commanded. In this case, the driving torque of the engine E is not reduced and is output to the output side of the starting clutch CL2, that is, to the driving wheels RR and RL. For this reason, fluctuations in the output torque and vehicle acceleration larger than the target may be caused, and the driver may feel uncomfortable.

  Therefore, in the second embodiment, when a vehicle start request is made at an extremely low temperature, braking control for preventing fluctuations in output torque is executed. Specifically, as in the first embodiment, the cryogenic temperature control process shown in the flowchart of FIG. 6 is executed.

  In the configuration of the second embodiment, a torque converter is not provided, and the engine torque is applied to the drive wheels RL and RR while slip control is performed on the start clutch CL2 interposed between the engine E and the drive wheels RL and RR. In the vehicle that transmits and starts, the same effects (1) to (6) as in the first embodiment can be obtained.

  As mentioned above, although Example 1 and 2 were demonstrated, this invention is not restricted to the said Example 1, 2, The other Example which can implement invention is also accept | permitted.

  In the first and second embodiments, the braking force used for suppressing the output torque fluctuation (and making a half-clutch trigger) is pulsed, but the input torque Tin to the automatic transmission AT and the output required torque TCL2 * of the second clutch CL2 The excess output torque may be suppressed by a ramp-like braking force with the difference | Tin−TCL2 * | as the upper limit. A plurality of braking forces may be combined. Further, when the ramp-like braking force is used, the torque on the input side of the second clutch CL2 is increased by the amount of the braking force applied to the output side of the second clutch CL2, and this is caused by the applied braking force. Torque pulling may be eliminated to improve drivability.

1 is an overall system diagram illustrating a hybrid vehicle to which a control device according to a first embodiment is applied. 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 the EV-HEV selection map used for selection of the target mode in the mode selection part of FIG. 3 is a flowchart showing a second clutch engagement control process at the time of an engine start request according to the first embodiment. It is a figure which shows the structure of the control part at the time of the cryogenic temperature of Example 1. FIG. 3 is a flowchart illustrating a cryogenic temperature control process executed in a cryogenic temperature control unit according to the first embodiment. It is a whole system figure which shows the vehicle to which the control apparatus of Example 2 was applied.

Explanation of symbols

E engine
CL1 1st clutch
MG motor generator
CL2 2nd clutch
AT automatic transmission
RL Left rear wheel (drive wheel)
RR Right rear wheel (drive wheel)
FL left front wheel
FR Right front wheel
BURL Left rear wheel brake unit
BURR Right rear wheel brake unit
BUFL Left front wheel brake unit
BUFR Right front wheel brake unit 1 Engine controller 2 Motor controller 7 AT controller 7a AT oil temperature sensor 8 Second clutch hydraulic unit 9 Brake controller 10 Integrated controller 401 Target engagement torque calculator 402 Engagement torque controller 410 Engine start controller 600 Cryogenic Time control unit 601 Cryogenic temperature determination unit 602 Vehicle speed detection unit 603 Engine start request detection unit 604 Start request detection unit 605 Half clutch request detection unit 606 Half clutch trigger making control unit 607 Differential rotation detection unit 608 Brake control command unit

Claims (7)

In a vehicle control device comprising: a driving force source; a fastening element interposed between the driving force source and the driving wheel; and an electronically controlled brake that automatically applies a braking force to the wheel.
Fastening torque control means for controlling the fastening torque of the fastening element;
Vehicle control means for controlling a fastening torque of the fastening element at a cryogenic temperature, and a control means for cryogenic temperature that outputs a command to the electronically controlled brake and applies a predetermined braking force to the wheel. Control device.   The said fastening element is a wet multi-plate clutch which comprises a plurality of friction plates immersed in hydraulic oil and generates a fastening capacity by the frictional force between the plurality of friction plates. The vehicle control device described.   The cryogenic temperature control means outputs a command to the driving force source or the actuator of the fastening element to output a half-clutch state of the fastening element before outputting a command to the electronically controlled brake when the vehicle speed is not zero. The vehicle control device according to claim 1, wherein the first trigger making control is executed.   4. The vehicle control device according to claim 3, wherein the cryogenic temperature control means executes second trigger making control for creating a half-clutch state of the engaging element using the predetermined braking force. 5.   5. The vehicle control device according to claim 1, wherein the command to the electronically controlled brake is a command to generate a pulse-like braking force on a wheel. 6.   6. The vehicle control device according to claim 1, wherein when the vehicle speed is zero, the cryogenic temperature control means outputs a complete engagement command to the electronic control brake. 7.   The vehicle includes an engine and a motor generator as the driving force source, the fastening element is interposed between the motor generator and the driving wheel, and a second fastening element is provided between the engine and the motor generator. The vehicle control device according to claim 1, wherein the vehicle control device is a hybrid vehicle interposed therebetween.

Images