JP2014226975A - Start control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress rapid rising of acceleration when starting a vehicle.SOLUTION: An electronic control device 1 includes: a drive control portion that, when a vehicle cannot be started by a drive torque imparted to a drive wheel even though a braking torque of a braking device 4 is not imparted to a wheel, increases the drive torque; and a braking control portion that imparts the braking torque of the braking device 4 to the wheel when the vehicle starts accompanying the increase in the drive torque, where the braking control portion performs a prefill control of reducing a distance between a frictioning material and a frictioned material in the braking device 4 after a parking brake is released and until the vehicle starts.

Description

  The present invention relates to a start control device that drives a vehicle from a stopped state.

  Conventionally, this kind of start control device is known. For example, in Patent Document 1 below, when a vehicle is in a stopped state even when driving torque is generated when climbing a step, the vehicle is started by increasing the driving torque, and the driving torque is suppressed after climbing the step. Alternatively, a technique is disclosed in which braking torque is applied to suppress a sudden increase in vehicle speed when descending a step. The following Patent Document 2 discloses a technique that, when releasing the parking brake, increases the pressing force of the brake shoe to the drum so as to eliminate these sticking. Further, in Patent Document 3 below, when a driver's braking operation is detected, a technique for performing a fill-up control that causes the brake pad to approach the disc rotor and reducing an idle stroke between them is provided. It is disclosed.

JP 2007-077871 A JP 2010-241271 A JP 2010-247793 A

  By the way, the parking brake device is fixed between the friction material and the friction target material due to rust or icing during the engagement operation when the vehicle is stopped, and performs a release operation between the friction material and the friction material. Even if torque is generated, the fixed state may not be resolved. For this reason, by applying the technique of Patent Document 1 to a vehicle in which the parking brake device is in a fixed state, the vehicle can start with the fixed state of the parking brake device canceled by an increase in driving torque. it can. However, the technique of Patent Document 1 suppresses driving torque or applies braking torque based on detection of climbing of a step from a stopped state (that is, starting of a vehicle). Therefore, even if the parking brake device is fixed and the vehicle can be started, if the control response of the driving torque or braking torque is low, it may not be possible to suppress a sudden rise in acceleration.

  Therefore, an object of the present invention is to provide a start control device that can improve the disadvantages of the conventional example and can suppress a sudden rise in acceleration when the vehicle starts.

  In order to achieve the above object, the present invention provides a driving torque which is applied when the vehicle cannot be started with the driving torque applied to the driving wheel even though the braking torque of the braking device is not applied to the wheel. And a braking control unit that applies braking torque of the braking device to the wheels when the vehicle starts with an increase in the driving torque, and the braking control unit includes: Pre-fill control is performed to reduce the distance between the friction material and the friction material in the braking device before the vehicle starts after the parking brake release operation.

  Here, the prefill control starts the vehicle with the driving torque applied to the driving wheels after the parking brake releasing operation and the braking torque of the braking device is not applied to the wheels. It is desirable to implement when this is not possible.

  Further, it is desirable that the braking torque of the braking device applied as the vehicle starts corresponds to an increase in the driving torque immediately before starting the vehicle.

  In addition, after the braking torque of the braking device is applied, the drive control unit decreases the increase in the driving torque so that the jerk becomes 0, and the braking control unit decreases the applied amount of the braking torque. It is desirable to make it.

  In the start control device according to the present invention, after the parking brake is released, the vehicle starts by keeping the distance between the friction material and the friction material in the braking device in advance before the vehicle starts. It is possible to improve the output response of the braking torque that is sometimes applied. Therefore, this start control device can suppress the response delay of the deceleration rising due to the application of the braking torque with respect to the acceleration rising due to the increased driving torque, thereby suppressing the sudden acceleration rising at the start of the vehicle. Can do.

FIG. 1 is a diagram showing a configuration of a start control device according to the present invention. FIG. 2 is a flowchart for explaining a control operation at the time of vehicle start of the start control device according to the present invention.

  Embodiments of a start control device according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the embodiments.

[Example]
An embodiment of a start control device according to the present invention will be described with reference to FIGS.

  The start control device of the present embodiment performs vehicle control (mainly braking / driving force control) at the time of vehicle start, and includes an electronic control unit (ECU) 1 that performs arithmetic processing related to the vehicle control.

  A vehicle having this start control device is provided with at least one power source 2 and a transmission 3 as drive devices. The power source 2 is, for example, an engine (an engine such as an internal combustion engine) or a rotating machine (such as an electric motor). The illustrated transmission 3 is an automatic transmission. The operations of the power source 2 and the transmission 3 are controlled by the drive control unit of the electronic control unit 1.

  The vehicle further includes a braking device 4. The brake device 4 exemplified here is a so-called disc brake device, and can apply a braking torque according to the master cylinder pressure or the brake fluid pressure after pressure adjustment to the wheels. An example of the braking device 4 will be described below.

  The braking device 4 can individually generate braking torque for each wheel. The braking device 4 includes a hydraulic pressure generating device 20 that generates a brake hydraulic pressure (master cylinder pressure) according to an operation amount (hereinafter referred to as “brake operation amount”) of the brake pedal 10 of the driver, a brake Braking torque generators 30fr, 30rl, 30fl, 30rr for each wheel that generate a braking torque corresponding to the hydraulic pressure, and the brake hydraulic pressure of the hydraulic pressure generator 20 is adjusted as it is or for each wheel to generate each braking torque. A hydraulic pressure adjusting device 40 that supplies the devices 30fr, 30rl, 30fl, and 30rr is provided. The braking torque generators 30fr, 30rl, 30fl, and 30rr include wheel cylinders 31fr, 31rl, 31fl, and 31rr that are operated by supplied hydraulic pressure, and brakes that include friction materials that are pushed by the wheel cylinders 31fr, 31rl, 31fl, and 31rr. Pads 32fr, 32rl, 32fl, and 32rr, and disk rotors 33fr, 33rl, 33fl, and 33rr as friction materials against which the friction material of the brake pads 32fr, 32rl, 32fl, and 32rr is pressed are provided.

  Connected to the brake pedal 10 are a stop lamp switch 11 that detects the operation (braking operation) and an operation amount detector 12 that detects a brake operation amount (such as a pedal depression amount and a pedal depression force). Output signals from the stop lamp switch 11 and the operation amount detector 12 are sent to the electronic control unit 1.

  The hydraulic pressure generator 20 includes a braking booster (brake booster) 21, a master cylinder 22, and a reservoir tank 23. The braking booster 21 is for doubling the driver's pedal effort at a predetermined boost ratio. The master cylinder 22 generates the master cylinder pressure in the two internal hydraulic chambers according to the pedal depression force (the sum of the pedal depression force of the driver and the assist force of the braking booster portion 21) multiplied by the braking booster portion 21. It is something to be made. The reservoir tank 23 stores the brake fluid at the upper part of the master cylinder 22. The master cylinder 22 and the reservoir tank 23 are in communication with each other when the brake pedal 10 is not depressed, and become closed when the brake pedal 10 is depressed. For this reason, each hydraulic chamber of the master cylinder 22 can be pressurized as the brake pedal 10 is depressed.

  A first hydraulic pressure passage 24 and a second hydraulic pressure passage 25 are connected to each hydraulic chamber of the master cylinder 22, respectively. The first and second hydraulic pressure passages 24 and 25 are further connected to the hydraulic pressure adjusting device 40, and send the brake fluid of the master cylinder pressure to the hydraulic pressure adjusting device 40. A master cylinder pressure sensor 26 is connected to the first hydraulic pressure passage 24. The master cylinder pressure sensor 26 is disposed between the master cylinder 22 and a master cut valve 41 of a first hydraulic circuit described later. The output signal of the master cylinder pressure sensor 26 is sent to the electronic control unit 1. Note that the master cylinder pressure sensor 26 may be connected to the second hydraulic pressure passage 25.

  The operation of the hydraulic pressure adjusting device 40 is controlled by the braking control unit of the electronic control device 1. The hydraulic pressure adjusting device 40 includes a first hydraulic pressure circuit that transmits brake hydraulic pressure to the right front wheel and the left rear wheel, a second hydraulic pressure circuit that transmits brake hydraulic pressure to the left front wheel and the right rear wheel, It is exemplified as a so-called X-pipe having the above. In the hydraulic pressure adjusting device 40, the first hydraulic pressure passage 24 is connected to the first hydraulic pressure circuit, and the second hydraulic pressure passage 25 is connected to the second hydraulic pressure circuit.

  Specifically, the hydraulic pressure adjusting device 40 includes two master cut valves 41 and 42. The master cut valve 41 functions as a brake fluid flow rate adjusting unit in the first hydraulic pressure circuit, and is connected to an end of the first hydraulic pressure passage 24. The master cut valve 42 functions as a brake fluid flow rate adjusting unit in the second hydraulic circuit, and is connected to an end of the second hydraulic pressure passage 25. The master cut valves 41 and 42 are so-called normally-open electromagnetic valves for flow rate adjustment, and execute control of the valve opening toward the closing side in accordance with energization by the braking control unit. Therefore, the master cut valves 41 and 42 adjust the pressure of the brake fluid discharged from the pressurizing pumps 79 and 80, which will be described later, by controlling the valve opening according to the energization amount, and move to the master cylinder 22 side. Open.

  In the hydraulic pressure adjusting device 40, the first hydraulic pressure passage 24 is connected to the connection passage 43 via the master cut valve 41, while the second hydraulic pressure passage 25 is connected to the connection passage 44 via the master cut valve 42. Connected. Two branch passages 45 and 46 are connected to the connection passage 43. Each of the branch passages 45 and 46 is connected to the wheel cylinder 31fr of the braking torque generator 30fr for the right front wheel and the wheel cylinder 31rl of the braking torque generator 30rl for the left rear wheel, respectively. On the other hand, two branch passages 47 and 48 are connected to the connection passage 44. The branch passages 47 and 48 are respectively connected to the wheel cylinder 31fl of the braking torque generator 30fl for the left front wheel and the wheel cylinder 31rr of the braking torque generator 30rr for the right rear wheel.

  On each of the branch passages 45, 46, 47, 48, a hydraulic pressure adjusting unit is provided for each wheel. Each of the hydraulic pressure adjusting sections is capable of adjusting the brake hydraulic pressure of each of the braking torque generators 30fr, 30rl, 30fl, and 30rr. Each of the hydraulic pressure adjusting units includes holding valves 50, 51, 52, and 53, hydraulic pressure discharge passages 54, 55, 56, and 57, and pressure reducing valves 58, 59, 60, and 61, respectively. The holding valves 50, 51, 52, 53 are arranged on the branch passages 45, 46, 47, 48, respectively. Each hydraulic pressure discharge passage 54, 55, 56, 57 is connected to the branch passage 45, 46, 47, 48 on the downstream side of the respective holding valve 50, 51, 52, 53. Each pressure reducing valve 58, 59, 60, 61 is disposed on its respective branch passage 45, 46, 47, 48. The term “downstream” as used herein refers to the downstream side in the flow direction of the brake fluid during the braking operation (that is, the direction toward the braking torque generators 30fr, 30rl, 30fl, and 30rr).

  The holding valves 50, 51, 52, and 53 are so-called normally-open electromagnetic valves, and execute control of the valve opening toward the closing side when energized by the braking control unit. On the other hand, the pressure reducing valves 58, 59, 60, 61 are so-called normally-closed electromagnetic valves, and execute control of the valve opening to the valve opening side when energized by the braking control unit.

  A check valve 62 is disposed between the first hydraulic pressure passage 24 and the connection passage 43 in parallel with the master cut valve 41. The check valve 62 allows only the flow of brake fluid from the first hydraulic pressure passage 24 side to the connection passage 43 side. In the same manner, a check valve 63 is disposed in parallel with the master cut valve 42 between the second hydraulic pressure passage 25 and the connection passage 44. The check valve 63 allows only the flow of brake fluid from the second hydraulic pressure passage 25 side to the connection passage 44 side. In the first hydraulic circuit, a check valve 64 is disposed in parallel with the holding valve 50 between the connection passage 43 and the branch passage 45, and the check valve 65 is provided between the connection passage 43 and the branch passage 46. Is arranged in parallel with the holding valve 51. In the second hydraulic circuit, a check valve 66 is disposed in parallel with the holding valve 52 between the connection passage 44 and the branch passage 47, and a check valve 67 is held between the connection passage 44 and the branch passage 48. It is arranged in parallel with the valve 53. The check valves 64, 65, 66, 67 allow only the flow of brake fluid from the wheel cylinders 31fr, 31rl, 31fl, 31rr side to the master cut valves 41, 42 side.

  Further, here, the collecting passage 68 that brings together the respective hydraulic pressure discharge passages 54 and 55 in the first hydraulic circuit, and the collecting passage that brings together the respective hydraulic pressure discharge passages 56 and 57 in the second hydraulic circuit. 69 are prepared. The collecting passages 68 and 69 are connected to the auxiliary reservoirs 70 and 71, respectively. A suction passage 72 branched from the first hydraulic pressure passage 24 is connected to the auxiliary reservoir 70, and a suction passage 73 branched from the second hydraulic pressure passage 25 is connected to the auxiliary reservoir 71. Reservoir cut check valves 74 and 75 are provided on the suction passages 72 and 73, respectively. The reservoir cut check valves 74 and 75 allow only the flow of brake fluid from the auxiliary reservoirs 70 and 71 side to the first and second hydraulic pressure passages 24 and 25 side.

  Further, the first hydraulic circuit is provided with a pump passage 76 that is branched from the connection passage 43 on the upstream side of the holding valves 50 and 51 and connected to the collecting passage 68. In the same manner, the second hydraulic circuit is provided with a pump passage 77 branched from the connection passage 44 on the upstream side of the holding valves 52 and 53 and connected to the collecting passage 69. On each of the pump passages 76 and 77, pressurizing pumps (pressurizing units) 79 and 80 driven by an electric motor 78, and on the master cut valves 41 and 42 side and the holding valve 50 from the pressurizing pumps 79 and 80. , 51, 52, and 53 are provided with check valves 81 and 82, respectively. The check valves 81 and 82 allow only the flow of brake fluid from the pressurizing pumps 79 and 80 side to the master cut valves 41 and 42 side and the holding valves 50, 51, 52 and 53 side.

  The operation of the braking device 4 configured as described above is controlled by the electronic control device 1 as described above.

  Specifically, the brake operation amount detected by the operation amount detector 12 and the master cylinder pressure detected by the master cylinder pressure sensor 26 are input to the electronic control unit 1. Based on the brake operation amount and the master cylinder pressure, the braking control unit of the electronic control unit 1 performs master cut valves 41, 42, holding valves 50, 51, 52, 53 and pressure reducing valves 58, 59, 60, 61. And the motor 78 (pressurizing pumps 79 and 80) are controlled to adjust the hydraulic pressure supplied to the wheel cylinders 31fr, 31rl, 31fl and 31rr, thereby controlling the braking torque of each wheel. At this time, the braking control unit calculates the driver's required braking force based on the brake operation amount. The braking control unit calculates the required braking torque in each of the braking torque generators 30fr, 30rl, 30fl, and 30rr according to the required braking force, and generates the required braking torque. Control.

  In the braking device 4, the master cut valves 41 and 42 and the holding valves 50, 51, 52, and 53 are open during normal times (in a non-excited state), and the pressure reducing valves 58, 59, 60, and 61 are open. Is closed. Therefore, when the driver depresses the brake pedal 10, a master cylinder pressure corresponding to the pedal depression force doubled by the braking booster 21 is generated.

  In the pressure increasing mode for increasing the brake fluid pressure of the wheel cylinders 31fr, 31rl, 31fl, 31rr, the master cut valves 41, 42, the holding valves 50, 51, 52, 53 and the pressure reducing valves 58, 59, 60 , 61 are driven and controlled with the pressure pumps 79, 80 in the normal state. As a result, the pressurizing pumps 79 and 80 pressurize and discharge the brake fluid in the auxiliary reservoirs 70 and 71, and the pressurizing pressure, together with the master cylinder pressure, passes through the holding valves 50, 51, 52, and 53. The cylinders 31fr, 31rl, 31fl, and 31rr are operated. Therefore, in the braking device 4, the braking torque of the braking torque generators 30fr, 30rl, 30fl, 30rr can be increased.

  On the other hand, in the pressure reducing mode for reducing the brake fluid pressure of the wheel cylinders 31fr, 31rl, 31fl, 31rr, the master cut valves 41, 42 and the holding valves 50, 51, 52, 53 are closed while the pressure reducing valve 58 is closed. , 59, 60, 61 are opened. As a result, the brake fluid is sent to the auxiliary reservoirs 70 and 71, and the surplus at that time is sent to the suction passages 72 and 73. Therefore, in this braking device 4, the braking torque of the braking torque generators 30fr, 30rl, 30fl, 30rr can be reduced.

  When the brake fluid pressure reaches a predetermined brake fluid pressure in the pressure increasing mode or the pressure reducing mode, the brake control unit performs the master cut valves 41, 42, the holding valves 50, 51, 52, 53, and the pressure reducing valves 58, 59, 60 and 61 are closed. In this holding mode, the brake fluid pressure of the wheel cylinders 31fr, 31rl, 31fl, 31rr is held at the predetermined brake fluid pressure.

  The vehicle further includes a parking brake device 5. The parking brake device 5 illustrated here includes a brake shoe having a friction material (not shown) and a drum as a friction material, and applies braking torque to the wheel by pressing the friction material of the brake shoe against the drum. The parking brake device 5 includes the brake shoe and the drum, for example, on the rear wheel. In the parking brake device 5, when the friction material and the friction material are engaged, the parking brake switch 6 is turned on, and the on signal is transmitted to the electronic control device 1. In this vehicle, the braking device 4 may be used as a parking brake device instead of such a parking brake device 5. For example, the rear wheel side of the braking device 4 can be replaced with a so-called drum brake device. In this case, the drum brake device may be used as a parking brake device.

  Here, as described above, the parking brake device 5 is fixed between the friction material and the friction target material due to rust or freezing during the engaging operation at the time of stopping, and performs the releasing operation between the friction material and the vehicle. Even if the driving torque (creep torque) at the time of starting is generated, the fixed state may not be solved even though the braking device 4 does not generate the braking torque. For this reason, when the vehicle cannot be started with the driving torque (creep torque) applied to the driving wheels even though the braking torque of the braking device 4 is not applied to the wheels when the vehicle starts, the driving is performed. By increasing the torque, the fixed state is eliminated.

  By the way, when the fixed state is eliminated in this way, the drive torque is larger than the creep torque by the increase, so the acceleration rises more suddenly than the driver intended, and the starting vehicle speed is increased. There is a possibility that it will soar. Therefore, when the vehicle starts with an increase in the driving torque, the braking device 4 applies braking torque to the wheels, thereby suppressing a sudden rise in acceleration that is not intended by the driver. However, in the braking device 4, a predetermined gap is provided between the friction material of the brake pads 32fr, 32rl, 32fl, and 32rr and the disk rotors 33fr, 33rl, 33fl, and 33rr in order to suppress wear and drag loss during non-braking. Therefore, the generation of the braking torque is delayed by at least the gap. In a vehicle, when the braking torque is generated with a delay from the start of the vehicle, it is not possible to suppress a sudden rise in acceleration immediately after the start.

  Therefore, in this start control device, the brake applied when the vehicle starts is executed by performing prefill control for reducing the distance between the friction material and the friction material in the brake device 4 before the vehicle starts at the latest. Improve torque output response. For example, the start control device performs pre-fill control until the vehicle starts after the parking brake release operation. If the execution time of the prefill control is made clearer, the brake control unit performs the prefill control when the vehicle does not start after the release operation of the parking brake device 5.

  Hereinafter, the control operation at the time of vehicle start in this start control device will be described based on the flowchart of FIG. The start control unit of the electronic control device 1 starts this control together with, for example, unlocking the door of the vehicle or turning on the ignition.

  First, the start control unit determines whether or not a control start condition for this control is satisfied (step ST1). For example, when fixing due to rust is eliminated, it is determined in this step ST1 whether or not the parking brake device 5 has been operated. This determination may be performed based on the ON signal of the parking brake switch 6 at the present time (immediately after the door is unlocked), for example, when this control is started when the door is unlocked. May be performed based on the ON signal or the reception history of the ON signal that has been received until immediately before the ignition is turned off. The start control unit determines that the control start condition is satisfied when the parking brake device 5 is operating. On the other hand, when the parking brake device 5 is not operating, the start control unit determines that the control start condition is not satisfied because the parking brake device 5 is less likely to stick, and ends the present control. When fixing due to freezing is eliminated, in step ST1, a detection signal from the outside air temperature sensor 7 is used to determine whether or not the outside of the vehicle has a temperature that can freeze. The start control unit determines that the control start condition is satisfied when the temperature outside the vehicle is freezing. On the other hand, when the temperature outside the vehicle is higher than the temperature at which icing can occur, the start control unit determines that the control start condition is not satisfied because the possibility of fixing due to icing is low, and ends the present control.

  The start control unit starts the power source 2 when the control start condition is satisfied, and sets the shift range of the transmission 3 to a travel range (so-called D range, R range, range for each shift stage). ) (Step ST2), a command is sent to the drive control unit to generate a creep torque Tc (= Tc0) (step ST3).

  If the parking brake device 5 performs a release operation in response to a driver release operation or a vehicle-side release command and the foot is released from the brake pedal 10 (service brake off) (step ST4), the start control unit Is determined to be stopped (step ST5). This determination is performed based on a detection signal of the vehicle speed detection device 8 such as a vehicle speed sensor or a wheel speed sensor.

  When the vehicle starts, the start control unit determines that the parking brake device 5 is not in a fixed state, and ends this control.

  On the other hand, when the vehicle is stopped, the start control unit passes control to the braking control unit because the parking brake device 5 may be in a fixed state. The braking control unit controls the hydraulic pressure adjusting device 40 to the pressure increasing mode, and the friction material (friction material of the brake pads 32fr, 32rl, 32fl, 32rr) and the friction material (disk rotors 33fr, 33rl, 33fl) in the braking device 4 are controlled. , 33rr), the prefill control is performed to reduce the distance (step ST6). When the distance between them becomes a predetermined distance, the brake control unit switches the hydraulic pressure adjusting device 40 from the pressure increasing mode to the holding mode, and controls the distance to be maintained at the predetermined distance. The predetermined distance is such that when the distance between the friction material and the friction target material is maintained at a predetermined distance, drag loss (braking torque) does not occur between them, and the holding mode is switched to the pressure increasing mode again. The distance at which the braking torque is generated immediately after switching. For example, the braking control unit may reduce the distance between the friction material and the friction material so that the friction material and the friction material do not contact each other but generate a braking torque immediately when the pressure increasing mode is entered. Control to zero. Further, the brake control unit pushes the brake pads 32fr, 32rl, 32fl, and 32rr to a position where the friction material and the friction material are in contact with each other (until the distance between the friction material and the friction material becomes zero). However, the control is performed so that the braking torque (the drag loss) is not substantially generated only by the contact between the friction material and the friction material.

  After executing the prefill control, the start control unit sends a command to the drive control unit to increase the creep torque Tc (step ST7). The increase ΔTc reflects, for example, the results of experiments and simulations performed a plurality of times, and is an average value of drive torque Ts (hereinafter referred to as “fixing cancellation torque”) Ts that cancels the locked state of the parking brake device 5. You may decide based on. In this case, the minimum value of the increment ΔTc is obtained by subtracting the normal creep torque Tc0 from the average value of the sticking elimination torque Ts. However, since the fixed state is not always the same, the fixed release torque Ts is not always constant. For this reason, a predetermined value (for example, a value smaller than the average value of the sticking elimination torque Ts) is set in advance for the increment ΔTc used in step ST7. Then, the drive control unit repeatedly adds the increment ΔTc until the increased creep torque Tc (= Tc + ΔTc) exceeds the current sticking elimination torque Ts and the vehicle can start.

  The start control unit determines whether or not the vehicle is stopped after the creep torque Tc is increased (step ST8). When the vehicle is stopped, the start control unit sends a command to the drive control unit, and returns to step ST7 to increase the creep torque Tc again. Then, when the vehicle starts to move, the start control unit sends a command to the braking control unit to cause the braking device 4 to apply the braking torque Tb (step ST9). The braking torque Tb is the sum of the braking torques generated by the respective wheels, and is made to coincide with the increment ΔTc of the creep torque Tc increased immediately before the vehicle starts. In the braking device 4, since the prefill control described above is performed, the braking torque Tb acts with good responsiveness together with the generation command of the braking torque Tb. Accordingly, in the vehicle, a sudden acceleration rise when the vehicle starts is suppressed.

  The start control unit sends commands to the drive control unit and the braking control unit to control the creep torque Tc and the braking torque Tb so that the jerk ΔG becomes zero (step ST10). Here, the creep torque Tc is reduced to the magnitude of the normal creep torque Tc0, and the braking torque Tb is reduced to zero. Thereby, in the vehicle, fluctuations in acceleration / deceleration due to the increase ΔTc of the creep torque Tc and the braking torque Tb are suppressed, and the impact at the time of starting the vehicle can be mitigated.

  The start control unit determines whether or not the braking torque Tb has decreased to 0 (step ST11). The start control unit repeats the control of step ST10 if the braking torque Tb is not yet zero, and ends this control if the braking torque Tb is reduced to zero.

  Here, the various controls after the prefill control in this control are interrupted regardless of whether the vehicle starts or not, respecting the driver's intention to stop when the driver's brake operation is performed. In this case, for example, if the parking brake device 5 is performing the releasing operation when the driver lifts his / her foot from the brake pedal 10 again, the process is restarted from step ST5. Further, various controls after the pre-fill control in this control are stopped regardless of before and after the vehicle start, respecting the driver's intention to start acceleration when the accelerator operation is performed. In this case, the fixed state of the parking brake device 5 is canceled by the driving torque corresponding to the accelerator operation.

  In this way, this start control device remains in the fixed state after the parking brake device 5 is released, and the normal creep torque is not applied to each wheel even though the braking torque of the braking device 4 is applied. If the vehicle cannot be started, the fixed state is eliminated by increasing the drive torque (creep torque). The start control device applies braking torque to each wheel by the braking device 4 when the fixed state is eliminated and the vehicle starts to start. At that time, the start control device performs the above-mentioned prefill control from when the parking brake device 5 is released to when the vehicle starts, and in advance between the friction material and the friction material of the brake device 4. Thus, the vehicle starts to start and the braking device 4 can generate braking torque with good responsiveness. Therefore, this start control device suppresses a sudden rise in acceleration when the vehicle starts because the response delay of the deceleration rise due to the application of braking torque is suppressed with respect to the acceleration rise due to the increased driving torque. This can eliminate the driver's uncomfortable feeling.

  Here, the prefill control is to start the vehicle with the driving torque applied to the driving wheels after the parking brake releasing operation and the braking torque of the braking device 4 is not applied to the wheels. We carry out when we cannot do. That is, this start control device avoids the prefill control when the parking brake device 5 is not fixed, and performs the prefill control when the parking brake device 5 is highly likely to be fixed. Therefore, since the start control device does not perform unnecessary control of the braking device 4 when it is not necessary to perform the prefill control, the power consumption required for the drive control of the motor 78 for the prefill control is suppressed. Can do.

  Further, this start control device performs the above-mentioned prefill control before increasing the drive torque (creep torque) in a stopped state. For this reason, for example, even when the vehicle starts with a slight increase in driving torque, this start control device applies braking torque with good responsiveness as the vehicle starts, and sudden acceleration when the vehicle starts Can be suppressed. Therefore, it is desirable that the start control device performs the prefill control regardless of whether or not the start control device detects an increase in driving torque (creep torque) in a stopped state.

  Further, the start control device decreases the increase of the drive torque (creep torque) and the braking torque so that the jerk becomes zero immediately after the braking torque is applied. Therefore, this start control device can alleviate the impact when the vehicle starts.

DESCRIPTION OF SYMBOLS 1 Electronic controller 2 Power source 3 Transmission 4 Braking device 5 Parking brake device 6 Parking brake switch 7 Outside air temperature sensor 8 Vehicle speed detection device 10 Brake pedal 20 Fluid pressure generating device 30fr, 30rl, 30fl, 30rr Braking torque generating device 40 Fluid Pressure regulator 78 Electric motor 79, 80 Pressurizing pump

Claims (4)

A drive control unit for increasing the drive torque when the vehicle cannot be started with the drive torque applied to the drive wheels despite the fact that the braking torque of the brake device is not applied to the wheels;
A braking control unit that applies a braking torque of the braking device to the wheels when the vehicle starts with an increase in the driving torque;
With
The brake control unit performs a start-up control for reducing the distance between the friction material and the friction material in the braking device after the parking brake is released and before the vehicle starts. apparatus.   The pre-fill control is performed after the parking brake releasing operation and when the vehicle cannot be started with the driving torque applied to the driving wheel even though the braking torque of the braking device is not applied to the wheel. The start control device according to claim 1, wherein the start control device is implemented as follows.   3. The start control device according to claim 1, wherein the braking torque of the braking device applied as the vehicle starts corresponds to an increase in the driving torque immediately before starting the vehicle.   After the braking torque of the braking device is applied, the drive control unit decreases the increase of the driving torque so that the jerk becomes 0, and the braking control unit decreases the applied amount of the braking torque. The start control device according to claim 1, 2 or 3.

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