JP5724291B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device that performs slip control on a fastening element between a power source and drive wheels.

  As a vehicle control device, a technique described in Patent Document 1 is disclosed. This gazette discloses a technique for performing an engine use slip mode in which the driving force of both the engine and the motor is used to start while slipping the clutch between the motor and the drive wheels. And when it is determined that the vehicle is stopped by adjusting the accelerator opening on the gradient road, so-called accelerator hill hold state, while releasing the clutch and avoiding the rollback by applying the brake fluid pressure, The clutch is protected.

JP 2009-162291 A

  However, since the method of raising the braking torque is not taken into account, for example, if the braking torque is raised at a stretch with a gentle gradient, there is a risk that the vehicle will be shocked. On the other hand, the braking torque is gradually raised at a steep gradient. If it is raised, there is a risk of rollback.

  The present invention has been made paying attention to the above problems, and an object thereof is to provide a vehicle control device capable of improving drivability.

When the accelerator hill hold state is determined, mechanical braking torque is applied to the wheels, and when the mechanical braking torque exceeds a predetermined value set according to the detected road gradient, the driving source Engagement element protection control for reducing the output of the engagement torque of the clutch between the drive wheels is executed. At this time, the increase gradient of the mechanical braking torque is set to a larger increase gradient as the road surface gradient is larger.

  Therefore, when the road surface gradient is large, the braking torque rises with a large increase gradient, so that the clutch slip state can be suppressed while avoiding rollback. Further, when the road surface gradient is small, the braking torque rises with a small increasing gradient, so that the shock accompanying the generation of the braking torque can be suppressed.

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 showing the relationship between a mode map and an estimated gradient in the mode selection 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 a figure which shows the MWSC corresponding | compatible mode map used for selection of the target mode in the mode selection 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 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. It is a time chart showing the change of the engine speed when raising a vehicle speed in a predetermined state. 6 is a flowchart illustrating a second clutch protection control process according to the first embodiment. 6 is a flowchart illustrating a second clutch protection control intervention control process according to the first embodiment. 3 is a torque change gradient setting map according to the first embodiment. It is a time chart when carrying out an accelerator hill hold on a slope.

  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 gear 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.

  The brake unit 900 includes a hydraulic pressure pump and a plurality of electromagnetic valves, so-called brakes that secure the hydraulic pressure corresponding to the required braking torque by increasing the pump pressure, and control the wheel cylinder pressure by controlling the opening and closing of the electromagnetic valves of each wheel. By-wire control is possible. Each wheel FR, FL, RR, RL is provided with a brake rotor 901 and a caliper 902, and generates a friction braking torque by the brake fluid pressure supplied from the brake unit 900. In addition, the type provided with the accumulator etc. may be sufficient as a hydraulic pressure source, and the structure provided with the electric caliper instead of the hydraulic brake may be sufficient.

  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). More detailed engine control contents will be described later. 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 the wheel speed sensor 19 and the brake stroke sensor 20 that detect the respective wheel speeds of the four wheels. For example, when braking the brake, the driver requested braking torque obtained from the brake stroke BS is applied. When the regenerative braking torque 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 torque (braking torque by the friction brake). Needless to say, the brake fluid pressure can be arbitrarily generated not only by the brake fluid pressure corresponding to the driver requested braking torque but also by other control requirements.

  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.

  Further, the integrated controller 10 includes a gradient load torque equivalent value calculation unit 600 that calculates an equivalent value of a gradient load torque acting on the wheel based on an estimated road gradient described later, and a driver brake when a predetermined condition is satisfied. A second clutch protection control unit 700 that generates brake fluid pressure regardless of the pedal operation amount is provided.

  The value corresponding to the gradient load torque is a value corresponding to the load torque acting on the wheels when the gravity acting on the vehicle due to the road surface gradient tries to move the vehicle backward. A brake that generates mechanical braking torque on a wheel generates braking torque by pressing a brake pad against a brake rotor 901 by a caliper 902. Therefore, when the vehicle is about to move backward due to gravity, the direction of the braking torque is the vehicle forward direction. The braking torque that coincides with the vehicle forward direction is defined as the gradient load torque. Since this gradient load torque can be determined by the road surface gradient and the inertia of the vehicle, a gradient load torque equivalent value is calculated based on the vehicle weight or the like preset in the integrated controller 10. Note that the gradient load torque may be set as an equivalent value as it is, or may be set as an equivalent value by adding or subtracting a predetermined value or the like.

  The second clutch protection control unit 700 calculates a braking torque minimum value (braking torque equal to or greater than the above-described gradient load torque) that can avoid a so-called rollback in which the vehicle moves backward when the vehicle stops on a gradient road. When the condition (the road surface gradient is equal to or greater than a predetermined value and the vehicle is stopped) is satisfied, the braking torque minimum value is output to the brake controller 9 as the control lower limit value.

  In the first embodiment, the brake fluid pressure is applied only to the rear wheels that are drive wheels. However, the brake fluid pressure may be supplied to the four wheels in consideration of the front and rear wheel distribution, or the brake fluid pressure may be supplied only to the front wheels.

  On the other hand, when the predetermined condition is not satisfied, a command for gradually decreasing the braking torque is output. Further, the second clutch protection control unit 700 outputs a request for prohibiting the output torque capacity control output to the second clutch CL2 to the AT controller 7 when a predetermined condition is satisfied.

  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 (driver required torque) 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.

  Furthermore, the mode selection unit 200 includes a mode map selection unit 202 that selects one of two mode maps described later based on the estimated road surface gradient. FIG. 4 is a schematic diagram illustrating the selection logic of the mode map selection unit 202. The mode map selection unit 202 switches to the gradient road corresponding mode map when the estimated gradient becomes a predetermined value g2 or more from the state in which the normal mode map is selected. On the other hand, when the estimated gradient becomes less than the predetermined value g1 (<g2) from the state where the gradient road corresponding mode map is selected, the mode is switched to the normal mode map. That is, a hysteresis is provided for the estimated gradient to prevent control hunting during map switching.

  Next, the mode map will be described. The mode map includes a normal mode map that is selected when the estimated gradient is less than a predetermined value, and a gradient path corresponding mode map that is selected when the estimated gradient is greater than or equal to a predetermined value. FIG. 5 shows a normal mode map, and FIG. 6 shows a gradient road corresponding 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 and the motor generator torque corresponding to the engine speed near the idle speed. 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 gradient road mode map differs from the normal mode map in that the EV drive mode area is not set. Further, the WSC travel mode area is different from the normal mode map in that the area is not changed according to the accelerator pedal opening APO and the area is defined only by the lower limit vehicle speed VSP1.

  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. In the target charge / discharge amount map, the EVON line (MWSCON line) for enabling or disabling the EV driving mode is set to SOC = 50%, and the EVOFF line (MWSCOFF line) is set to SOC = 35%. Yes.

  When SOC ≧ 50%, the EV driving mode area appears in the normal mode map of FIG. Once the EV area appears in the mode map, it 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 (driver required torque), the target mode, the vehicle speed VSP, and the target charging / discharging power tP as transient targets for these operating points. The target engine torque, the target motor generator torque, the target second clutch transmission torque capacity TCL2 *, the target gear position of the automatic transmission AT, and the 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.

  Shift control unit 500 drives and controls a solenoid valve in automatic transmission AT so as to achieve the target second clutch transmission torque capacity TCL2 * 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 changes in driver request torque. Specifically, the first clutch CL1 is completely engaged, the second clutch CL2 is slip-controlled as the transmission torque capacity TCL2 corresponding to the driver request torque, and the vehicle travels using the driving force of the engine E and / or the 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. Further, when the driver required torque 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 the restriction based on the battery SOC, or in a region where the driver required torque cannot be achieved only by the motor generator MG, there is no means other than generating stable torque by the engine E.

  Therefore, in a vehicle speed range lower than the vehicle speed corresponding to the lower limit value, and when it is difficult to travel in the EV travel mode, or in a region where the driver required torque cannot be achieved only by the motor generator MG, the engine speed is set to a predetermined value. While maintaining the lower limit rotational speed, the second clutch CL2 is slip-controlled, and the WSC traveling mode for traveling using the engine torque is selected.

  FIG. 8 is a schematic diagram showing the engine operating point setting process in the WSC running mode, and FIG. 9 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, the target engine speed characteristic corresponding to the accelerator pedal opening is selected based on FIG. 9, and the target engine speed corresponding to the vehicle speed is set along this characteristic. Is done. 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. 8, it is desirable that the engine operating point be 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 (driver required torque). 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, 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 automatically feedback-controlled. It becomes.

  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 driver request torque. 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 driver required torque 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, by collecting the energy corresponding to the increased output by the motor generator MG, the torque itself input to the second clutch CL2 becomes the driver request torque, 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. 8A 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. 8B 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. 8C is a schematic diagram when the engine operating point is higher than the α line. When the operating point corresponding to the driver required torque 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 driver required torque can be achieved while improving the fuel efficiency.

  Next, the point that the WSC traveling mode area is changed according to the estimated gradient will be described. FIG. 10 is an engine speed map when the vehicle speed is increased in a predetermined state. When the accelerator pedal opening is larger than APO1 on a flat road, the WSC drive mode region is executed up to a vehicle speed region higher than the lower limit vehicle speed VSP1. At this time, as the vehicle speed increases, the target engine speed gradually increases as shown in the map of FIG. Then, when the vehicle speed corresponding to VSP1 ′ is reached, the slip state of the second clutch CL2 is canceled and the state transits to the HEV travel mode.

  If an attempt is made to maintain the same vehicle speed increase state as described above on a gradient road where the estimated gradient is larger than the predetermined gradient (g1 or g2), the accelerator pedal opening is increased accordingly. At this time, the transmission torque capacity TCL2 of the second clutch CL2 is larger than that on a flat road. In this state, if the WSC travel mode area is enlarged as shown in the map shown in FIG. 9, the second clutch CL2 will continue to slip with a strong engagement force, and the amount of heat generated may be excessive. is there. Therefore, in the gradient road corresponding mode map of FIG. 6 selected when the estimated gradient is a large gradient road, the WSC travel mode region is not unnecessarily widened, but the region corresponding to the vehicle speed VSP1. This avoids excessive heat generation in the WSC travel mode.

  In such a WSC traveling mode, a case where a so-called accelerator hill hold is performed in which the vehicle is stopped only by operating the accelerator pedal without reaching the slope road and the driver operating the brake pedal will be examined. In this case, since the brake pedal is not operated, the brake unit 900 that generates the mechanical braking force is not operated, and the slip control of the second clutch CL2 is continued, so that the vehicle stop state is maintained. Then, there existed a problem that durability of the 2nd clutch CL2 fell.

  Therefore, in the first embodiment, when it is determined that the accelerator hill hold is performed when the gradient road corresponding mode map is selected, the braking unit 900 generates a braking force based on the brake hydraulic pressure, and stops the vehicle. The second clutch protection control for reducing the engagement capacity of the second clutch CL2 is executed.

  Here, when the second clutch protection control is performed at the time of accelerator hill hold, even if it is determined that the vehicle is stopped because the driver has not depressed the brake pedal, the vehicle still moves slightly. In such a case, if the brake fluid pressure is increased at once, there is a risk of generating a shock. On the other hand, on a steep road surface, if the brake fluid pressure is not supplied as soon as possible, there is a possibility that the durability of the second clutch CL2 may be deteriorated due to a slip state or rollback may occur.

  Therefore, in the first embodiment, when the second clutch protection control is performed, the brake fluid pressure is increased according to the road surface gradient so as to avoid the shock and the rollback. Details will be described below.

[Second clutch protection control process when the gradient road mode map is selected]
Next, the second clutch protection control process when the gradient road corresponding mode map is selected will be described based on the flowchart of FIG. FIG. 11 is a flowchart showing the second clutch protection control process of the first embodiment.

  In step S1, it is determined whether or not the road gradient estimated by the road gradient estimation calculation unit 201 is equal to or greater than a predetermined value (g1 or g2). If it is equal to or greater than the predetermined value, the process proceeds to step S2, and otherwise, step S8 is performed. Proceed to

  In step S2, it is determined whether or not the vehicle speed is substantially zero. If it is determined that the vehicle speed is substantially zero, the process proceeds to step S3. Otherwise, the process proceeds to step S8. Here, “substantially 0” means, for example, whether or not the vehicle speed is in an extremely low vehicle speed region of about 1 km / h to 2 km / h.

  In step S3, it is determined whether or not the brake pedal is OFF. When the brake pedal is depressed, the process proceeds to step S8, and when it is not depressed, the process proceeds to step S4. Whether or not the brake pedal is depressed is determined, for example, by turning the brake switch ON / OFF when the sensor value of the brake stroke sensor 20 is equal to or greater than a predetermined value indicating an invalid stroke or a separate brake switch is provided. do it.

  In step S31, it is determined whether or not the driver request torque corresponding to the driver's accelerator pedal operation amount is within a predetermined range. If it is within the predetermined range, the process proceeds to step S4, and if outside the predetermined range, the process proceeds to step S8. Here, the predetermined range refers to a range that is equal to or greater than the intervention determination lower limit torque obtained by subtracting a predetermined value from the gradient load torque and is equal to or less than the intervention determination upper limit torque obtained by adding a predetermined value to the gradient load torque. When the road surface gradient is large, the gradient load torque also increases, and therefore, an upper limit torque and a lower limit torque are set based on the gradient load torque. By setting a certain range in this way, the second clutch protection control can be executed stably even if there is a variation in the transmission torque capacity of the second clutch CL2 or a variation in the vehicle weight.

  In step S4, it is determined whether or not the second clutch protection control request flag is OFF. If it is ON, this control flow is terminated.

In step S5, the second clutch protection control request flag is set to ON. In the second clutch protection control, when the torque that the driver balances with the gradient load torque by the accelerator control is achieved by the second clutch slip control in the WSC travel mode, the torque is replaced by the gradient by the second clutch CL2. In this control, the brake fluid pressure is generated according to the braking torque equal to or greater than the load torque equivalent value. Specifically, the second clutch CL2 is released (that is, the second clutch transmission torque capacity is set to zero), and the brake fluid pressure corresponding to the braking torque equal to or greater than the gradient load torque equivalent value calculated in the brake controller 9 is set. generate. Thereby, even if the driver has stopped the gradient road surface by the accelerator control, the second clutch CL2 can be protected without continuing the slip state.
In step S6, the request flag is reset to OFF.

[Second clutch protection control intervention control process]
Next, the intervention control process of the second clutch protection control will be described. FIG. 12 is a flowchart showing the second clutch protection control intervention control process of the first embodiment.
In step S10, it is determined whether or not the request flag has been switched from OFF to ON. If the request flag has not been switched, the present control flow ends. If switched, the process proceeds to step S11.
In step S11, a braking torque increasing gradient corresponding to the detected gradient is set, and a driving torque decreasing gradient is set. Here, the braking torque increasing gradient represents the rising gradient of the brake fluid pressure, and the driving torque decreasing gradient represents the decreasing gradient of the transmission torque capacity of the second clutch CL2. FIG. 13 is a torque change gradient setting map of the first embodiment. As shown in FIG. 13, the greater the road gradient, the greater the braking torque increase gradient, and the greater the braking torque increase gradient (or road gradient), the greater the drive torque increase gradient. As a result, the braking torque gradually increases and the driving torque gradually decreases on the low gradient road, and the braking torque increases quickly and the driving torque decreases quickly on the high gradient road.

  In step S12, a brake fluid pressure increasing process is executed based on the braking torque increasing gradient set in step S11. As a result, the brake fluid pressure gradually increases with the set increase gradient, and finally increases until a braking torque equal to or greater than the gradient load torque equivalent value is generated.

  In step S13, it is determined whether or not the braking torque has reached the driving torque reduction permission braking torque. If it is determined that the braking torque has been reached, the process proceeds to step S14, and if not, this step is repeated. That is, if the driving torque is reduced in a state where the braking torque has not risen, rollback may be caused. The driving torque reduction permission braking torque is a value set in accordance with the road gradient, and is set to a large value on a high gradient road and set to a small value on a low gradient road.

  In step S14, a drive torque capacity reduction process is executed based on the drive torque increase gradient set in step S11. As a result, the transmission torque capacity of the second clutch CL2 gradually decreases with the set decreasing gradient, and is finally set to zero.

[Time chart when ramp stops]
FIG. 14 is a time chart when the accelerator hill hold is performed on the slope road. This time chart shows that the driver maintains the accelerator pedal at the value corresponding to the gradient load torque while the vehicle is stopped in the WSC drive mode with the estimated gradient greater than the predetermined value (g1 or g2) and the gradient road mode map selected. It represents the state that is. When the vehicle is stopped, the motor generator MG is in a power generation state while the engine E is being driven, as shown in FIG. In the drawing, the driving torque and the braking torque represent a state where the solid line is on a high gradient road and the dotted line is on a low gradient road.

  In the initial state, when the vehicle approaches the gradient road, gradient load torque is applied. As a result, the vehicle stops, but the driver maintains the accelerator pedal in the accelerator hill hold state while maintaining the accelerator pedal at a value corresponding to the gradient load torque while the brake pedal is OFF. Therefore, slip control is performed in a state where the clutch transmission torque capacity of the second clutch CL2 is set to a value higher than the value corresponding to the gradient load torque.

  At time t1, it is determined that the driver request torque is within the predetermined range, the request flag is turned ON, and the second clutch protection control process is executed. Specifically, first, the brake controller 9 starts generating the brake fluid pressure according to the braking torque equal to or greater than the gradient load torque equivalent value. At this time, a large increase gradient is set on the high gradient road, and a small increase gradient is set on the low gradient road.

  Then, at time t2 for the high gradient road, and at time t21 for the low gradient road, the braking torque reaches the driving torque reduction permission braking torque, and the reduction of the transmission torque capacity of the second clutch CL2 is started. Also in this case, a large decreasing gradient is set on the high gradient road, and a small decreasing gradient is set on the low gradient road. By this switching control, the vehicle shifts from the vehicle stop state due to the drive torque to the vehicle stop state due to the braking torque. Therefore, since the continuation of the slip state of the second clutch CL2 is avoided, the durability of the second clutch CL2 is improved and the driver feels uncomfortable because it is not different from the state where the vehicle is stopped by the driving torque. I will not give it. Furthermore, when the increase in the output of the engine E is prohibited, it is possible to suppress wasteful energy consumption while avoiding heat generation of the second clutch CL2 without rolling back the vehicle.

  Further, on a high gradient road, the braking torque rises quickly and the driving torque decreases quickly, so that the slip state in the second clutch CL2 can be suppressed. On the other hand, on a low slope road, the braking torque rises gently and the driving torque gradually decreases. Therefore, even if the second clutch protection control process is started while the vehicle is moving slightly, a shock can be avoided. it can. Further, since the driving torque is reduced after the braking torque has increased to the driving torque reduction permission braking torque, rollback can be avoided.

As described above, in the hybrid vehicle of the first embodiment, the following effects can be obtained.
(1) Based on the accelerator pedal opening and the second clutch CL2 (engagement element) that is interposed between the engine E and the motor generator MG (hereinafter referred to as a power source) and the drive wheels and connects and disconnects the power source and the drive wheels. A target driving force calculating unit 100 (requesting torque calculating means) for calculating the driver request torque, an AT controller 7 (engaging torque control means) for controlling the engagement torque of the second clutch CL2 based on the calculated request torque, A brake unit 900 (brake control means) capable of applying a mechanical braking torque to the wheels regardless of the operation of the brake pedal, a road surface gradient estimation calculation unit 201 (road surface gradient detection means) for detecting the road surface gradient, and the driver The step of determining whether or not the vehicle is in the accelerator hill hold state in which the vehicle is to be stopped by operating the accelerator pedal without operating the brake pedal. S1-31 (accel hill hold determination means) and when it is determined that the accelerator hill hold state, the brake unit 900 is used to apply mechanical braking torque to the wheel and the output of the fastening torque in the AT controller 7 is reduced. Second clutch protection control (engagement element protection control means) to be performed, and step S11 (torque change gradient setting means) for setting the increase gradient of the mechanical braking torque to a larger increase gradient as the detected road surface gradient is larger. Prepared.
Therefore, when the road surface gradient is large, the braking torque rises with a large increase gradient, so that the slip state of the second clutch CL2 can be suppressed. Further, when the road surface gradient is small, the braking torque rises with a small increasing gradient, so that the shock accompanying the generation of the braking torque can be suppressed.

  (2) Step S11 increases the decreasing gradient of the engagement torque of the second clutch as the increasing gradient of the mechanical braking torque increases. Therefore, when the increase gradient is large, the second clutch CL2 can be quickly released, and thus the slip state of the second clutch CL2 can be suppressed.

  (3) Step S13 starts decreasing the engagement torque of the second clutch CL2 when the braking torque becomes equal to or greater than the driving torque decrease permission braking torque (predetermined value) set according to the detected road surface gradient. . Therefore, rollback can be avoided.

(4) Engine E that is a power source, motor generator MG that is a power source, first clutch CL1 (first engaging element) that connects and disconnects engine E and motor generator MG, motor generator MG and drive wheels A second clutch CL2 (second engagement element) that is interposed between the motor generator MG and the drive wheel, and the first clutch LC1 is engaged with the engine E operated, and the second clutch CL2 is slip-engaged. WSC travel mode (engine-use slip travel control means) is provided, and the second clutch protection control is to release the second clutch CL2.
The WSC travel mode is a travel mode that can always be achieved regardless of the battery SOC conditions, and although sufficient driving torque can be secured, if the accelerator hill hold is continued, the durability of the second clutch CL2 may be reduced. There is. However, the amount of heat generated by the second clutch CL2 can be suppressed by the second clutch protection control, and durability can be improved while ensuring stable start performance.

  Although the present invention has been described based on the first embodiment, the specific configuration may be other configurations. For example, in the first embodiment, the present invention is applied to a hybrid vehicle, but the present invention can be similarly applied to any vehicle including a start clutch and a hill hold mechanism.

  In the first embodiment, the brake unit 900 is a means capable of arbitrarily setting the magnitude of the mechanical braking torque. For example, the wheel cylinder pressure generated by the driver's operation of the brake pedal is controlled by closing the pressure increasing valve. You may use the type enclosed in a cylinder. However, in order to reliably avoid the rollback, the wheel cylinder pressure generated by the driver's brake pedal operation needs to be equal to or greater than the gradient load torque.

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

  Further, in the first embodiment, while the second clutch CL2 is released by the second clutch protection control unit 700, it is configured to avoid an increase in the output torque of the engine E or the motor generator MG, but the driver feels uncomfortable. In order to reduce this, the engine speed or the like may be slightly increased. Even in this case, since the second clutch CL2 is released, it is still possible to avoid a decrease in durability.

  In the first embodiment, the mode map is switched as the gradient road start control. However, the transmission torque capacity TCL2 of the second clutch CL2 is set based on a value obtained by adding a predetermined value corresponding to the gradient to the driver request torque. You may control to do.

  Further, when the battery SOC is sufficient, the first clutch CL1 is released, and the second clutch CL2 protection control is performed in the MWSC travel mode in which the second clutch CL2 is slip-controlled while the engine is operating. It is good.

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
500 Shift control

Claims (3)

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;
Request torque calculating means for calculating the required torque based on the accelerator pedal opening;
A fastening torque control means for controlling a fastening torque of the fastening element based on the calculated required torque;
Brake control means capable of applying mechanical braking torque to the wheels regardless of brake pedal operation;
Road surface gradient detecting means for detecting the road surface gradient;
An accelerator hill hold determination means for determining whether or not the driver is in an accelerator hill hold state in which the vehicle is to be stopped by operating the accelerator pedal without operating the brake pedal on a slope road;
When the accelerator hill hold determination means determines that the vehicle is in the accelerator hill hold state, the brake control means is used to apply a mechanical braking torque to the wheel, and the mechanical braking torque depends on the detected road gradient. Fastening element protection control means for executing fastening element protection control for reducing the output of the fastening torque in the fastening torque control means when the predetermined value is greater than or equal to the preset value ,
Torque change gradient setting means for setting the increase gradient of the mechanical braking torque to a larger increase gradient as the detected road surface gradient is larger;
A vehicle control device comprising: The vehicle control device according to claim 1,
The vehicle torque control apparatus according to claim 1, wherein the torque change gradient setting means increases the decrease gradient of the fastening torque as the increase gradient of the mechanical braking torque increases. The vehicle control device according to claim 1 or 2,
An engine as the power source;
A motor as the power source;
A first fastening element interposed between the engine and the motor to connect and disconnect the engine and the motor;
A second fastening element interposed between the motor and the drive wheel to connect and disconnect the motor and the drive wheel;
Engine-use slip running control means for fastening the first fastening element and slip-fastening the second fastening element in a state where the engine is operated;
With
The vehicle control apparatus , wherein the fastening element is the second fastening element .

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