JP5092363B2 - Vehicle start control device - Google Patents

Description

  The present invention relates to a vehicle start control device including a vehicle start friction element.

Conventionally, in a vehicle equipped with an automatic transmission that is not equipped with a torque converter, when starting the vehicle, instead of the torque converter, a friction element (hereinafter referred to as a clutch) dedicated to starting or a clutch in the automatic transmission slips to make the vehicle smooth Starting off. For example, Patent Document 1 includes a starting clutch that is not equipped with a torque converter and that can connect and disconnect between a power source and an output shaft, and a clutch control unit that controls the degree of engagement of the starting clutch. A vehicle start control device is disclosed.
Japanese Patent Application Laid-Open No. 2004-169782.

  However, in the configuration described in Patent Document 1, since the starting clutch is slipped when the vehicle starts, the load on the starting clutch is heavy when the load applied to the vehicle is large, such as during steep climbing or trailer towing. That is, the amount of heat generated by the slip increases, and for example, the clutch plate may be seized and a fastening failure may occur, or the durability of the starting clutch may be reduced.

  As described above, when the vehicle load due to the road surface gradient, the vehicle weight, or the like is large, the amount of heat generated by the starting clutch increases, resulting in the following problems. First, it is difficult to apply to high power vehicles. Second, if the amount of heat generated per unit area of the clutch is reduced to improve the durability of the clutch, a clutch having a large diameter or a large number of plates is required. As a result, the clutch becomes larger and the vehicle mountability deteriorates. Third, a device for cooling the heat generation is required, and the cost of the clutch system increases.

  The present invention has been made paying attention to the above problems, and in a vehicle that starts smoothly by slipping the starting clutch, the durability of the starting clutch is improved and the size of the clutch system can be reduced. It is an object to provide a start control device.

In order to achieve the above object, in the vehicle start control device of the present invention, a power source, a friction element interposed between the power source and the drive wheel and connecting / disconnecting the power source and the drive wheel, and the vehicle And a fastening torque control means for setting a target value of a fastening torque of the friction element based on an accelerator opening, and controlling the fastening torque. and determining the vehicle load determiner, a fastening torque correcting means for increasing corrects the target value to be determined that the vehicle load is large, Ru reduces the output speed of the power source and it is determined that the vehicle load is large a slip amount control means Ru reduce the slip amount of the friction element, the provided by.

  Therefore, in the vehicle start control device of the present invention, when the vehicle starts, the amount of heat generated by the start clutch is controlled by controlling the slip amount of the start clutch based on the determination result of the vehicle load. The durability of the clutch can be improved and the clutch system can be downsized.

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

[Configuration of Example 1]
FIG. 1 is an overall system diagram showing a hybrid vehicle by rear wheel drive to which the start control device of Embodiment 1 is applied. First, the drive system configuration of this hybrid vehicle will be described. 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, a propeller shaft PS, and a differential DF. And 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 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 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. The hydraulic pressure controls the fastening and opening 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. This motor generator MG can also operate as an electric motor that is driven to rotate by receiving power supplied from the battery 4 (this state is called “powering”), and when the rotor is rotated by an external force, The battery 4 can also be charged by functioning as a generator that generates electromotive force at both ends of the stator coil (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 tightening / release including slip fastening and slip opening is controlled by the control hydraulic pressure.

  The automatic transmission AT is a transmission that automatically switches stepped gear ratios such as forward 5 speed, reverse 1 speed, etc. according to the vehicle speed VSP, accelerator opening APO, and the like. The second clutch CL2 is not newly added as a dedicated clutch, and uses some friction elements among a plurality of friction elements that are engaged at each gear stage of the automatic transmission AT.

  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. The first clutch CL1 and the second clutch CL2 are, for example, wet multi-plate clutches that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid.

  This hybrid drive system has three travel modes according to the engaged / released state of the first clutch CL1. The first travel mode is abbreviated as an “electric vehicle travel mode” (hereinafter referred to as “EV travel mode”) as a motor use travel mode in which the first clutch CL1 is disengaged and travels using only the power of the motor generator MG as a power source. ). 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) 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. Abbreviated as “travel mode”). This mode achieves creep running especially when the battery SOC is low or the engine water temperature is low. Furthermore, in this mode, the driving force can be output while starting the engine when starting from the engine stopped state.

  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-assisted travel mode”, the drive wheels are moved using the engine E and the motor generator MG as power sources. In the “traveling power generation mode”, the motor generator MG is caused to function as a power generator while 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, braking energy is regenerated and electric power is 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. , An AT controller 7, a second clutch hydraulic unit 8, a brake controller 9, and an integrated controller 10.

  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 receives input of engine speed information from the engine speed sensor 12 and calculates a command for controlling the engine operating point (Ne, Te) according to a target engine torque command or the like from the integrated controller 10. For example, output to a throttle valve actuator not shown. 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 receives input of information from the resolver 13 that detects the rotor rotational position of the motor generator MG, and according to the target motor generator torque command and the target motor generator rotational speed command from the integrated controller 10, A command for controlling the motor operating point (Nm, Tm) is calculated and 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. To do.

  Also provided is a motor torque estimation unit 2a that estimates a motor generator torque (hereinafter referred to as a motor torque Tm) based on the value of the current flowing through the motor generator MG (the driving torque and the regenerative torque are distinguished from each other depending on the sign of the current value). It has been. Information on the estimated motor torque Tm is supplied to the integrated controller 10 via the CAN communication line 11.

  The first clutch controller 5 receives input of sensor information from the first clutch hydraulic pressure sensor 14 and the first clutch stroke sensor 15, and engages / releases the first clutch CL1 in response to a first clutch control command from the integrated controller 10. Is calculated and 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 receives input of sensor information from the accelerator opening sensor 16, the vehicle speed sensor 17, and the second clutch hydraulic pressure sensor 18, and engages the second clutch CL <b> 2 according to the second clutch control command from the integrated controller 10.・ A command for controlling opening is calculated and output to the second clutch hydraulic unit 8 in the AT hydraulic control valve. Information about the accelerator opening AP and the vehicle speed VSP is supplied to the integrated controller 10 via the CAN communication line 11.

  The brake controller 9 receives input of sensor information from the wheel speed sensor 19 that detects the wheel speeds of the four wheels and the brake stroke sensor 20, and for example, with respect to the required braking force required from the brake stroke BS during brake depression braking. When the regenerative braking force alone is insufficient, the regenerative cooperative brake control is performed based on the regenerative cooperative control command from the integrated controller 10 so that the shortage is supplemented by the mechanical braking force (hydraulic braking force or motor braking force).

  The integrated controller 10 manages the energy consumption of the entire vehicle and assumes the function of running the vehicle with the highest efficiency. The motor controller 21 detects the motor generator rotation speed (hereinafter referred to as the motor rotation speed Nm), A second clutch output rotational speed sensor 22 that detects the second clutch output rotational speed N2out, a second clutch engagement torque sensor 23 that detects an engagement torque TCL2 of the second clutch, a brake hydraulic pressure sensor 24, and a vehicle acceleration. The information from the acceleration sensor 25 and the information obtained via the CAN communication line 11 are received. The second clutch output rotation speed N2out refers to the rotation speed of the output shaft on the drive wheel side of the second clutch CL2.

  The acceleration sensor 25 can detect whether or not the vehicle is located on a slope having a slope, and for example, a sensor equipped in a brake-by-wire system can be used. Here, the brake-by-wire is not mechanically linked between the brake pedal and the master cylinder, and electrically detects an operation on the brake pedal (brake stroke BS) and generates a braking force based on the detected value. Electronically controlled brake.

  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 determines the vehicle load at the time of starting the vehicle, and if it is determined that the vehicle load is large, the second clutch input is performed to prevent the second clutch CL2 from being overheated more than necessary. Start control is performed to reduce the rotational speed N2in (motor rotational speed Nm). The second clutch input rotational speed N2in refers to the rotational speed of the input shaft on the motor generator MG side of the second clutch CL2.

  Below, the control calculated by the integrated controller 10 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. In the EV-HEV selection map, the WSC mode is set in order to output a large driving force when the accelerator pedal opening APO is large in the low vehicle speed range. The HEV → WSC switching line or the 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 speed. In FIG. 4, the shaded area is the WSC drive mode area, and the shaded area is the hysteresis area between the WSC drive mode and the EV drive mode.

  The target charge / discharge calculation unit 300 calculates the target charge / discharge power tP from the battery SOC using a target charge / discharge amount map (not shown).

  The operating point command unit 400 uses the accelerator pedal opening APO, the target driving force tFoO, the target mode, the vehicle speed VSP, and the target charging / discharging power tP as a target for reaching the operating point, as a transient target engine torque. Te *, target motor torque Tm *, second clutch target engagement torque TCL2 *, target automatic shift shift, and first clutch solenoid current command are calculated. In addition, the operating point command unit 400 is provided with an engine start control unit (not shown) that performs start control of the engine E in the WSC drive mode or when the EV drive mode is changed to the HEV drive mode.

  Here, engine start control will be described. As will be described later, when an engine start request is made, the second clutch CL2 is slip-controlled, and at the same time, the rotational speed control of the motor generator MG is executed. When the engine start request is made, the target engagement torque TCL1 * of the first clutch CL1 is increased to a predetermined value. When the target engagement torque TCL1 * of the first clutch CL1 rises to a predetermined value, the load acting on the motor generator MG increases, but the motor torque Tm that is higher by the increase in load is automatically reset by the motor speed control. Is done. When the engagement torque TCL1 of the first clutch CL1 increases to an engagement torque that is about the torque required for starting the engine, cranking of the engine E is performed. The engine start is completed when the engine E starts to rotate independently.

  The target engagement torque calculation unit 401 calculates the target engagement torque TCL2 * of the second clutch CL2 based on the target driving force tFoO, and outputs the calculation result to the engagement torque control unit 402 and the switching unit 406. The target engagement torque calculator 401 has a map 1 shown in FIG. 5, and sets the target engagement torque TCL2 * based on this map 1 (solid line portion) when the vehicle starts with a vehicle speed VSP of zero or very small.

  The solid line portion of the map 1 indicates the target engagement torque TCL2 * with respect to the accelerator opening APO at a predetermined vehicle load (for example, a vehicle load when the vehicle is a flat road and a standard vehicle weight, hereinafter referred to as a standard vehicle load). The change characteristic is shown. At a predetermined vehicle load, the target engagement torque TCL2 * increases at a substantially constant rate according to the accelerator opening APO. Note that the accelerator opening APO in FIG. 5 corresponds to the target driving force tFoO when the vehicle speed VSP is zero or very small in FIG.

The engagement torque control unit 402 outputs the target engagement torque TCL2 * to the shift control unit 500, and controls the actual engagement torque TCL2 of the second clutch CL2 to be the target value TCL2 *.
The engagement torque estimation unit 405 estimates the actual engagement torque TCL2 of the second clutch CL2 based on the estimated motor torque Tm, the motor rotation speed Nm, etc., and outputs it to the switching unit 406.

  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 in the automatic transmission AT 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.

(Slip control and switching control of the second clutch)
At the time of a start request or an engine start request, the second clutch CL2 is slip-controlled, and the control unit 406 switches the control of the motor generator from torque control to rotation speed control. Thereafter, when a predetermined condition is satisfied, the rotational speed control is switched to the torque control, and the second clutch CL2 is completely engaged.

  That is, in the scene where the engine torque is generated in addition to the drive torque as the motor torque Tm as in the engine start, the engagement torque TCL2 of the second clutch CL2 is controlled. As a result, a value corresponding to the engagement torque of the second clutch CL2 is reliably output to the drive wheels, and the target drive force is achieved. At the same time, a torque greater than or equal to the second clutch engagement torque TCL2 is prevented from being output to the drive wheel side to achieve stable running or smooth start. Further, during the slip control, the control of the motor generator MG is switched from the torque control to the rotation speed control, thereby preventing excessive slip of the second clutch CL2. This will be specifically described below.

  When a start request or an engine start request is made, the target engagement torque TCL2 * of the second clutch is calculated based on the accelerator opening APO or the target driving force tFoO so that the actual engagement torque TCL2 becomes the target engagement torque TCL2 * Second clutch engagement torque control is executed. The second clutch actual engagement torque TCL2 used for the engagement torque control is estimated based on the motor rotation speed Nm and the detected engagement state of the first clutch CL1.

  At the same time, the motor rotation speed control is executed so that the input rotation speed N2in is slightly higher than the output rotation speed N2out of the second clutch CL2. Specifically, the output rotational speed N2out is read, and a value obtained by adding a predetermined slip amount to the rotational speed N2out is set as a target value for the input rotational speed N2in. Then, in order to achieve this target rotational speed N2in, 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 target motor rotational speed Nm *. Hereinafter, the predetermined slip amount is approximated by a difference rotational speed of the motor rotational speed Nm with respect to the vehicle speed VSP (output rotational speed N2out) and expressed as α or the like.

  As described above, when the motor generator MG is set to rotation speed control and the second clutch CL2 is set to engagement torque control, in order to maintain the motor rotation speed Nm higher than the output rotation speed N2out, the target driving force tFoO and the second clutch A motor torque Tm larger than the fastening torque TCL2 (including the torque necessary for engine cranking in the engine start control) is automatically set. Therefore, the engagement torque equivalent value of the second clutch CL2 is reliably output to the drive wheels RR and RL.

  When the engine is running (when EV → HEV running mode is switched), when engine start is completed, the motor speed control is switched to the motor torque control, and the second clutch CL2 is completely engaged. When the vehicle starts (in the WSC travel mode), the vehicle speed VSP is equal to or higher than the predetermined vehicle speed VSP1, and when a command for switching from the WSC travel mode to the HEV travel mode is output, the motor speed control is switched to the motor torque control, Fully engage second clutch CL2.

(Start control)
Next, the start control process of the present invention will be described. As described above, when the vehicle starts (in the WSC travel mode), the engagement torque TCL2 of the second clutch CL2 is controlled, and the target engagement torque TCL2 * is set according to the accelerator opening APO. At the same time, the target rotational speed Nm * of the motor generator MG is set to a value obtained by adding a predetermined slip amount α to the output rotational speed N2out.

  The vehicle load determination unit 407 determines the magnitude of the load applied to the vehicle when the vehicle starts and the presence or absence of a road surface gradient. Whether or not the vehicle is starting, that is, whether or not the vehicle is switched from the stop state to the start state is detected by determining whether or not the accelerator opening APO is greater than zero. In the present specification, the term “vehicle load” includes a weight load applied to the vehicle due to a road surface gradient. The vehicle load depends on the vehicle weight and the road surface gradient, and increases during uphill roads and trailer towing.

  The vehicle load determination unit 407 has a map 2 shown in FIG. 6, and determines a vehicle load including a road surface gradient state based on the map 2. The solid line part in Map 2 shows the target characteristic (expected vehicle speed VSP *) of the vehicle speed VSP for each accelerator opening APO at the standard vehicle load. At a predetermined accelerator opening APO, the predicted vehicle speed VSP * increases at a substantially constant rate with time t. Further, as the accelerator opening APO increases, the rate of change (inclination) of the predicted vehicle speed VSP * with time increases. This inclination indicates a target characteristic (expected acceleration G *) of the vehicle acceleration.

  If the accelerator opening APO is sufficiently large at the time of the start request, when the vehicle speed VSP is equal to or less than the predetermined value VSP1, the second clutch CL2 is slip-controlled in the WSC travel mode. Thereafter, when the vehicle speed VSP exceeds the predetermined value VSP1, the WSC travel mode is switched to the HEV travel mode (see FIG. 4), and the second clutch CL2 is completely engaged. Therefore, the time required for the vehicle speed VSP to increase from zero (at the time of start request) to the predetermined value VSP1 indicates the clutch engagement time Tc from when the second clutch CL2 starts slipping until it is fully engaged.

  The clutch engagement time Tc obtained from the solid line portion of the map 2 indicates a target characteristic of the clutch engagement time at a standard vehicle load, that is, an expected clutch engagement time Tc *. Since the slope of the predicted vehicle speed VSP * (predicted acceleration G *) changes according to the accelerator opening APO, the expected clutch engagement time Tc * also changes. Thus, when a predetermined accelerator opening APO is given, an expected clutch engagement time Tc * is also given.

  However, when the vehicle load is large, the starting torque is insufficient, and the actual acceleration G decreases with respect to the target characteristic (expected acceleration G *). The starting torque is calculated by subtracting the vehicle load torque (negative torque acting on the drive wheels RR and RL due to the vehicle load) from the target engagement torque TCL2 * (positive drive torque output to the drive wheels RR and RL). The driving torque that can be used for starting. Therefore, the actual vehicle speed VSP increases gradually with respect to the target characteristic (expected vehicle speed VSP *), and the actual clutch engagement time Tc becomes longer than the target characteristic (expected clutch engagement time Tc *).

  Thus, by comparing the actual acceleration G, the actual vehicle speed VSP, or the actual clutch engagement time Tc with these predicted values (target characteristics), it is possible to determine the vehicle load when the vehicle starts. The vehicle load determination unit 407 of the first embodiment determines the vehicle load based on the comparison result between the actual acceleration G and the expected acceleration G *.

  When it is determined that the vehicle load is large, the high load control unit 408 outputs a command to the target fastening torque calculation unit 401, and changes the characteristics of the map 1 (see FIG. 5) according to the vehicle load. The second clutch target engagement torque TCL2 * is corrected. Specifically, as the vehicle load increases, the change rate (slope) of the target engagement torque TCL2 * with respect to the accelerator opening APO is increased (dotted line portion in FIG. 5). In other words, the target engagement torque TCL2 * is increased and corrected as the vehicle load increases. As a result, the output torque of the second clutch CL2 is increased, and the starting torque is ensured.

  When the vehicle starts, the target engagement torque calculation unit 401 sets the target engagement torque TCL2 * based on the accelerator opening APO using the map 1 as described above. The target fastening torque calculation unit 401 is based on a standard vehicle load. That is, the target fastening torque TCL2 * is set using the solid line portion of the map 1. Here, the accelerator opening APO and the vehicle load are irrelevant. Therefore, the starting torque depends on the magnitude of the vehicle load. For example, when the vehicle load is large, since the large vehicle load torque is subtracted from the target fastening torque TCL2 * set on the assumption of the standard vehicle load, the starting torque may be insufficient. Therefore, in the start control of the present invention, when the vehicle load is large, control for increasing the target engagement torque TCL2 * (high load engagement torque control) is executed.

  When the high load control unit 408 determines that the vehicle load is large, in addition to the high load engagement torque control, the high load control unit 408 outputs a command to the motor rotation number control unit 403 to set the motor rotation number Nm to a predetermined amount. Just lower. As a result, the input rotational speed N2in of the second clutch CL2 decreases, the slip amount also decreases, and the frictional energy generated in the second clutch CL2 is suppressed. Since the motor torque Tm higher than the target engagement torque TCL2 * that has been increased and corrected as described above is automatically set by the motor rotation speed control, the minimum starting torque is ensured.

  If the slip amount in the motor rotation speed control is set to the same value α as before the execution of the high load engagement torque control, the clutch plates are pressed against each other with a higher frictional force by the increased engagement torque TCL2. In this state, the second clutch CL2 slips. Since the friction energy is given by the product of the friction force and the slip amount, the friction energy generated in the second clutch CL2 at this time increases, the heat generation amount increases, and the durability of the second clutch CL2 decreases. There is a fear. Therefore, in the start control of the present invention, when it is determined that the vehicle load is large, the slip amount is corrected to decrease. Specifically, the target rotational speed Nm * of motor generator MG is set low (motor rotational speed control at high load).

[Operation of Example 1]
FIG. 7 is a flowchart illustrating the flow of the start control process according to the first embodiment. This control is executed when there is a start operation by stepping on the accelerator while the vehicle is stopped (step S1). If it is detected that the accelerator opening APO is greater than zero, it is determined that a start request has been made, and the process proceeds to step S2.

  In step S2, the map 2 (see FIG. 6) is used to compare the expected acceleration G * corresponding to the accelerator opening APO and the actual acceleration G at a predetermined time t2 after the start request. When the predicted acceleration G * is the same as the actual acceleration G, or when the magnitude of the difference between the predicted acceleration G * and the actual acceleration G is less than the predetermined threshold ΔG, the process proceeds to step S3. Otherwise, the process proceeds to step S5. Proceed to

  In step S3, it is determined that the vehicle load is small (for example, it is a flat road, or a standard vehicle load that is lower than a threshold value that acts on the vehicle), and the process proceeds to step S4.

  In step S4, the second clutch CL2 is smoothly engaged while realizing the acceleration G corresponding to the driving force requested by the driver. Specifically, the target engagement torque TCL2 * corresponding to the accelerator opening APO is set using a standard vehicle load map (solid line portion of map 1). Thereby, the start without a fastening shock is realized.

  In step S5, the map 2 is used to compare the expected acceleration G * corresponding to the accelerator opening APO with the actual acceleration G. When the predicted acceleration G * is larger than the actual acceleration G and the magnitude of the difference between the predicted acceleration G * and the actual acceleration G is larger than a predetermined threshold ΔG (not shown), the process proceeds to step S6, and otherwise Advances to step S8.

  In step S6, it is determined that the vehicle load is large (for example, an uphill road or a load acting on the vehicle is higher than a certain threshold value), and the process proceeds to step S7.

  In step S7, the motor rotation speed Nm is reduced within a range in which the starting torque can be secured, and the second clutch CL2 is smoothly engaged. Specifically, the target engagement torque TCL2 * corresponding to the accelerator opening APO is set using a map whose characteristics are changed according to a large vehicle load (a dotted line portion of the map 1). As a result, the start without the fastening shock is realized while ensuring the durability of the second clutch.

  In step S8, since the actual acceleration G is larger than the expected acceleration G * corresponding to the accelerator opening APO, it is determined that the road is a downhill road, and the process proceeds to step S9. Even when the actual acceleration G is smaller than the predicted acceleration G *, the difference between the predicted acceleration G * and the actual acceleration G is smaller than the predetermined threshold ΔG, so the process proceeds to step S9.

  In step S9, as in step S4, the second clutch CL2 is smoothly engaged while realizing the acceleration G corresponding to the driving force requested by the driver. Thereby, the start without a fastening shock is realized.

(Time chart)
FIG. 8 is a time chart when the start control is executed when starting with a large vehicle load.
When the accelerator opening APO is switched from zero to a predetermined value APO1 at time t1, it is determined that there is a start operation (start request) due to depression of the accelerator (step S1). It is assumed that the accelerator opening APO1 is sufficiently large and the vehicle starts in the WSC traveling mode (shaded area in FIG. 4). Therefore, an engine start request is made at time t1.

  When the engine start request is made, the target engagement torque TCL1 * of the first clutch is increased from zero and set to the maximum value TCL1 * max (engine start control). Further, using map 1 (solid line portion) in FIG. 5, the second clutch target engagement torque TCL2 * 1 at a standard vehicle load corresponding to the accelerator opening APO1 is set (slip control). As a result, the target engagement torque TCL2 * decreases from the maximum value TCL2 * max to TCL2 * 1. Further, the control of the motor generator MG is switched from torque control to rotation speed control, and the target motor rotation speed Nm * is set to a value larger by a predetermined amount α than the second clutch output rotation speed N2out.

  Here, the torque obtained by subtracting the vehicle load torque Tf from the second clutch engagement torque TCL2 * is the starting torque T (G). Further, the rate of change (slope) of the vehicle speed VSP with time indicates the acceleration G, and the magnitude of the starting torque T (G) corresponds to the magnitude of the acceleration G. As shown in FIG. 8, the starting torque obtained by subtracting the large vehicle load torque Tf1 from the target engagement torque TCL2 * 1 before the time t2 when the high load engagement torque control is started is T (G1). Insufficient compared to the starting torque T (G *). Therefore, the acceleration G is also smaller than the expected acceleration G * corresponding to the accelerator opening APO.

  At time t2, the actually generated acceleration G1 is smaller than the expected acceleration G * and the difference | G * −G1 | is larger than a predetermined threshold ΔG (not shown). Hereinafter, it is determined that the load is high) (steps S2, S5, S6). Therefore, using map 1 in FIG. 5 (dotted line portion), the target engagement torque TCL2 * of the second clutch is corrected to increase from TCL2 * 1, and the target engagement torque TCL2 * at high load according to the accelerator opening APO is obtained. Set to 2 (step S7). The starting torque obtained by subtracting the large vehicle load torque Tf1 from the target fastening torque TCL2 * 2 at the time of high load is T (G2), which is substantially the same as the starting torque T (G *) at the time of standard load. Therefore, the acceleration G2 has substantially the same size as the expected acceleration G *, and a quick start is realized after time t2.

  Further, since it is determined that the load is high at time t2, the motor rotation speed Nm is decreased (step S7). Specifically, the target motor rotation speed Nm * is set to a value larger by a predetermined amount β than the second clutch input rotation speed N2out. β is set smaller than α at the standard load (β <α). Therefore, the slip amount of the second clutch CL2 is decreased by (α−β) than before the time t2. After the time t2, until the time t3 when switching to torque control, the slip amount of the second clutch CL2 is maintained while being reduced to a predetermined amount β (<α).

  Further, during the period from time t2 to t3, cranking and complete explosion of the engine E are completed by engine start control, and the engine E is started. A description of the change in the motor rotation speed Nm due to engine start is omitted and not shown.

  When the vehicle speed VSP reaches a predetermined value VSP1 at time t3, the WSC drive mode is switched to the HEV drive mode according to the EV-HEV selection map of FIG. Therefore, the slip control is terminated and the second clutch CL2 is completely engaged. That is, the target engagement torque TCL2 * is increased from the predetermined value TCL2 * 2 and set to the maximum value TCL2 * max. At the same time, the control of the motor generator MG is switched from the rotational speed control to the torque control.

(Function and effect in comparison with conventional technology)
In FIG. 8, the alternate long and short dash line indicates the time change of each variable when the actual start control (high load engagement torque control and high load motor rotation speed control) is not executed at high load. First, if the high torque engagement torque control is not performed, the target engagement torque TCL2 * is fixed at the standard load TCL2 * 1 even at high loads, so the starting torque is fixed at T (G1). It is insufficient compared to the standard load. For this reason, the acceleration G also becomes an acceleration G1 smaller than the expected acceleration G *, and a quick start is prevented.

  Second, even if the high torque engaging torque control is executed to achieve a quick start, the motor speed Nm * is not reduced (the motor speed control at high load is not executed). The slip amount of the two clutch CL2 is fixed to the slip amount α at the standard load. Therefore, the frictional energy (engagement torque x slip amount) generated in the second clutch CL2 increases according to the increase in the engagement torque TCL2 * | TCL2 * 2-TCL2 * 1 |, and the durability of the second clutch CL2 increases. descend.

  On the other hand, when this start control (high load engagement torque control and high load motor rotation speed control) is executed, at high load, the engagement torque TCL2 * is corrected to the predetermined value TCL2 * 2 for high load, Further, the motor rotation speed Nm * is decreased to decrease the slip amount of the second clutch CL2. That is, the slip amount corresponding to the shaded portion in FIG. 8 is reduced from the time t2 at which the high load is determined to the time t3 when the slip control of the second clutch CL2 is finished, and the second clutch is reduced by this decrease. Suppresses frictional energy generated in CL2. Accordingly, it is possible to improve the durability of the second clutch CL2 while realizing a quick start.

  The vehicle start control device according to the first embodiment can obtain the following effects.

  (1) Motor generator MG, second clutch CL2 interposed between motor generator MG and drive wheels RR and RL, and connecting and disconnecting motor generator MG and drive wheels RR and RL, and an accelerator when a vehicle is requested to start A vehicle start control device comprising: a fastening torque control means (target fastening torque calculation unit 401) for setting the target value TCL2 * of the fastening torque TCL2 of the second clutch CL2 based on the opening degree APO and controlling the fastening torque TCL2 Vehicle load determination unit 407 for determining the load applied to the vehicle, fastening torque correction means (high load control unit 408, map 1) for correcting the target engagement torque TCL2 * based on the vehicle load determination result, vehicle load Slip amount control means for controlling the slip amount of the second clutch CL2 by controlling the output rotational speed Nm of the motor generator MG which is a power source based on the determination result (high load control unit 408, motor rotational speed control unit 40 And 3).

  That is, for example, when it is determined that the vehicle load is large, the target engagement torque TCL2 * of the second clutch CL2 is increased and corrected according to the vehicle load, and the slip amount of the second clutch CL2 is decreased according to the vehicle load. Therefore, it is possible to secure a starting torque and realize a quick start, and at the same time, it is possible to improve the durability of the second clutch CL2 by suppressing the friction energy (heat generation amount) generated in the second clutch CL2. Therefore, the starting clutch (second clutch CL2) can be applied to a high-power vehicle instead of the torque converter, and the clutch system can be miniaturized to improve the vehicle mountability and reduce the cost.

  (2) The slip amount control means (high load control unit 408, motor rotation speed control unit 403) controls the slip amount of the second clutch CL2 by controlling the output rotation speed Nm of the motor generator MG as a power source. It was decided to.

  As described later, the slip amount may be controlled by controlling the output torque Tm of the motor generator MG and the output torque Te of the engine E. However, in that case, the slip amount is indirectly controlled, and there is a possibility that accurate control cannot be performed. On the other hand, by controlling the slip amount directly by motor rotation speed control, accurate control can be realized, and the effect (1) can be obtained with certainty.

  (3) After the vehicle start request, the acceleration sensor 25 for detecting the actual vehicle acceleration G is provided, and the vehicle load determination unit 407 calculates the acceleration G at a predetermined vehicle load for each accelerator opening APO after the vehicle start request. The vehicle has a predicted acceleration prediction means (map 2) and determines the vehicle load based on the comparison result between the detected acceleration G and the predicted acceleration G.

  In this way, a map (map 2) of acceleration G * predicted for each accelerator opening APO in a standard vehicle load is provided, and by using this to determine the vehicle load, the presence or absence of the vehicle load and its magnitude Can be determined easily and quickly.

  (4) The engine E and the motor generator MG are provided as power sources, and a second friction element (first clutch CL1) that connects and disconnects the engine E and the motor generator MG is interposed between the engine E and the motor generator MG. The second clutch CL2 was interposed between the motor generator and the drive wheels RR and RL.

  That is, when the start control device of the present invention is applied to a hybrid vehicle having the above-described configuration, the above-described effects (1) to (3) can be obtained.

  The configuration of the start control device of the second embodiment is the same as that of the first embodiment. On the other hand, the vehicle load determination unit 407 of the second embodiment is different from the first embodiment in that the vehicle load is determined based on the comparison result of the vehicle speed VSP.

FIG. 9 is a flowchart illustrating the flow of the start control process according to the second embodiment.
In step S21, the predicted vehicle speed VSP * corresponding to the accelerator opening APO is compared with the actual vehicle speed VSP at a predetermined time t2 after the start request using the map 2 shown in FIG. When the predicted vehicle speed VSP * is the same as the actual vehicle speed VSP, or when the magnitude of the difference between the predicted vehicle speed VSP * and the actual vehicle speed VSP is less than the predetermined threshold value ΔVSP, the process proceeds to step S3. Otherwise, the process proceeds to step S51. Proceed to

  In step S51, the map 2 is used to compare the predicted vehicle speed VSP * corresponding to the accelerator opening APO with the actual vehicle speed VSP. If the predicted vehicle speed VSP * is greater than the actual vehicle speed VSP and the magnitude of the difference between the predicted vehicle speed VSP * and the actual vehicle speed VSP is greater than the predetermined threshold ΔVSP, the process proceeds to step S6. Otherwise, the process proceeds to step S8. .

  Other steps S1 and the like are the same as those in the first embodiment.

  The start control device of the second embodiment can obtain the following effects.

  (5) After the vehicle start request, the vehicle speed sensor 17 for detecting the actual vehicle speed VSP is provided, and the vehicle load determination unit 407 predicts the vehicle speed VSP at a predetermined vehicle load for each accelerator opening APO after the vehicle start request. Vehicle speed prediction means (map 2) for determining the vehicle load based on the comparison result between the detected vehicle speed VSP and the predicted vehicle speed VSP.

  As described above, a map (map 2) of the vehicle speed VSP * predicted for each accelerator opening APO in a standard vehicle load is provided, and by using this to determine the vehicle load, the presence or absence of the vehicle load and its magnitude Can be determined easily and quickly.

  The configuration of the start control device of the third embodiment is the same as that of the first embodiment. The vehicle load determination unit 407 of the third embodiment is different from the first and second embodiments in that the vehicle load is determined based on the comparison result of the clutch engagement time Tc.

FIG. 10 is a flowchart illustrating the flow of the start control process according to the third embodiment.
In step S22, the map 2 shown in FIG. 6 is used to compare the expected clutch engagement time Tc * corresponding to the accelerator opening APO with the actual clutch engagement time Tc. If the estimated clutch engagement time Tc * is the same as the actual clutch engagement time Tc, or the difference between the estimated clutch engagement time Tc * and the actual clutch engagement time Tc is less than the predetermined threshold value ΔTc, the process proceeds to step S3. In other cases, the process proceeds to step S52.

  In step S52, the map 2 is used to compare the expected clutch engagement time Tc * corresponding to the accelerator opening APO with the actual clutch engagement time Tc. Step when the estimated clutch engagement time Tc * is longer than the actual clutch engagement time Tc and the difference between the estimated clutch engagement time Tc * and the actual clutch engagement time Tc is greater than a predetermined threshold ΔTc (not shown) Proceed to S6, otherwise proceed to step S8.

  Other steps S1 and the like are the same as those in the first embodiment.

  The start control device of the third embodiment can obtain the following effects.

  (6) Engagement time detection means (accelerator opening sensor 16, vehicle speed sensor 17, etc.) for detecting clutch engagement time Tc until the second clutch CL2 is completely engaged after the vehicle start request is provided, and vehicle load determination The unit 407 has engagement time prediction means (map 2) for predicting the clutch engagement time Tc * at a predetermined vehicle load for each accelerator opening APO, and the detected clutch engagement time Tc and the estimated clutch engagement time Tc * The vehicle load is determined based on the comparison result.

  As described above, a map (map 2) of the clutch engagement time Tc * expected for each accelerator opening APO in a standard vehicle load is provided, and by using this to determine the vehicle load, The size can be easily and quickly determined.

  As mentioned above, although the vehicle start control apparatus of the present invention has been described based on the first to third embodiments, the specific configuration is not limited to these embodiments, and each claim of the claims Design changes and additions are allowed without departing from the gist of the invention. In the first to third embodiments, an example in which a clutch built in the automatic transmission is used as the second clutch CL2 is shown. However, the second clutch CL2 is additionally provided between the motor generator MG and the transmission AT. Alternatively, a second clutch CL2 may be added between the transmission AT and the drive wheels RR and RL (for example, see Japanese Patent Application Laid-Open No. 2002-144922).

In the first to third embodiments, the slip amount of the second clutch CL2 is directly controlled by controlling the output rotation speed Nm of the motor generator MG as a power source. The slip amount may be indirectly controlled by controlling Tm (motor torque control).
Furthermore, the vehicle start control device of the present invention can be applied to a vehicle having only the start clutch (second clutch CL2), and also to a vehicle having only the engine E without the motor generator MG as a power source. it can. In this case, by controlling the engine torque Te, the engine speed Ne can be reduced, and thereby the slip amount of the starting clutch (second clutch CL2) can be reduced.

  Although the acceleration sensor 25 for detecting the vehicle acceleration is provided, the vehicle acceleration (acceleration G) may be calculated based on the input information from the vehicle speed sensor 17 without providing the acceleration sensor 25.

1 is an overall system diagram showing a hybrid vehicle to which a start control device of Embodiment 1 is applied. FIG. 3 is a control block diagram illustrating an arithmetic processing unit 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. It is a figure which shows the map 1 used for the setting of the 2nd clutch target fastening torque of Example 1. FIG. It is a figure which shows the map 2 used for the vehicle load determination of Example 1. FIG. 3 is a flowchart illustrating a start control process according to the first embodiment. 3 is a time chart illustrating a start control process according to the first embodiment. 6 is a flowchart illustrating a start control process according to the second embodiment. 10 is a flowchart illustrating a start control process according to the third embodiment.

Explanation of symbols

E engine
MG motor generator
CL2 2nd clutch
AT automatic transmission
RL Left rear wheel (drive wheel)
RR Right rear wheel (drive wheel)
DESCRIPTION OF SYMBOLS 1 Engine controller 2 Motor controller 7 AT controller 8 2nd clutch hydraulic unit 10 Integrated controller 16 Accelerator opening degree sensor 17 Vehicle speed sensor 21 Motor rotational speed sensor 22 Second clutch output rotational speed sensor 25 Acceleration sensor
100 Target driving force calculator
200 Mode selection section
400 Operating point command section
407 Vehicle load determination unit
408 High load control unit
500 Shift control

Claims (5)

Power source,
A friction element interposed between the power source and the drive wheel to connect and disconnect the power source and the drive wheel;
A fastening torque control means for setting a target value of a fastening torque of the friction element based on an accelerator opening and controlling the fastening torque at the time of a vehicle start request;
In a vehicle start control device comprising:
Vehicle load determination means for determining a load applied to the vehicle;
A fastening torque correction means for increasing the target value when it is determined that the vehicle load is large ;
Start control of the vehicle, characterized by comprising a slip amount control means Ru reduce the slip amount of the friction element by Rukoto to be determined that the vehicle load is large reduces the output speed of the power source, the apparatus. In the vehicle start control device according to claim 1,
After the vehicle start request, an acceleration detection means for detecting the actual vehicle acceleration is provided,
The vehicle load determination means is
After the vehicle start request, the vehicle has acceleration prediction means for predicting vehicle acceleration at a predetermined vehicle load for each accelerator opening,
A vehicle start control device that determines a vehicle load based on a comparison result between the detected acceleration and the predicted acceleration . In the vehicle start control device according to claim 1 or 2,
A vehicle speed detecting means for detecting the actual vehicle speed after the vehicle start request is provided,
The vehicle load determination means is
A vehicle speed prediction means for predicting the vehicle speed at a predetermined vehicle load for each accelerator opening after the vehicle start request;
A vehicle start control device, wherein a vehicle load is determined based on a comparison result between the detected vehicle speed and the predicted vehicle speed . In the vehicle start control device according to any one of claims 1 to 3,
A fastening time detecting means for detecting a fastening time until the friction element is completely fastened after a vehicle start request is provided,
The vehicle load determining means,
It has a fastening time expected means to predict the engagement time in a predetermined vehicle load per accelerator opening,
A vehicle start control device that determines a vehicle load based on a comparison result between the detected engagement time and the predicted engagement time . The vehicle start control device according to any one of claims 1 to 4,
An engine and a motor generator as the power source;
A second friction element for connecting and disconnecting the engine and the motor generator is interposed between the engine and the motor generator;
A vehicle start control device , wherein the friction element is interposed between the motor generator and the drive wheel .

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