JP2016080030A - Control device of vehicular automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of a vehicular automatic transmission capable of reducing slip-down of a vehicle, in down-shift after the vehicle is stopped on an uphill road.SOLUTION: In execution of down-shift during stop of a vehicle on an uphill road, compared to a case where the vehicle does not stop on the uphill road, by performing control to perform delivery of torque between engagement devices to be gripped alternately on a tie-up side, since force in a lock direction acts on a rotation member in an automatic transmission, slip-down of the vehicle can be suppressed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a control device for an automatic transmission for a vehicle, and more particularly to control at the time of starting from stopping on an uphill road.

  In a vehicular automatic transmission, in a control device for a vehicular automatic transmission that maintains a gear other than the lowest gear when the vehicle is stopped and performs a downshift when the throttle is opened, a change in throttle opening or throttle opening A device having means for reducing engine torque when at least one of the rates is equal to or less than a predetermined value is disclosed. This is the control apparatus for an automatic transmission for a vehicle disclosed in Patent Document 1. In Patent Document 1, the downshift is executed by opening the throttle valve. At this time, when the throttle valve opening or its rate of change is small, the engine torque is reduced, and the vehicle starts from a stop state. The shift shock felt when performing is reduced.

JP-A-5-263923

  By the way, the case where it decelerates while drive | working an uphill road, and stops a vehicle after that can be considered. And when a downshift is performed at the timing when the driver's intention to start is detected by depressing the accelerator pedal after the vehicle stops, especially in vehicles that do not have a hill hold function to prevent the vehicle from falling There is a possibility that the torque will be lost when the gripping of the engaging device during downshifting is carried out, and the vehicle will slide down.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide an automatic transmission for a vehicle that can reduce the sliding of the vehicle during a downshift after the vehicle is stopped on an uphill road. It is to provide a control device.

  In order to achieve the above object, the gist of the first invention is that: (a) In a vehicle equipped with a stepped vehicle automatic transmission capable of shifting in multiple stages by changing the engagement device, An automatic transmission for a vehicle that stops the vehicle at a speed other than the lowest speed of the automatic transmission, and performs a downshift by grasping the engagement device when a driver's intention to start is detected while the vehicle is stopped. (B) When the downshift is performed while the vehicle is stopped on the uphill road, the engagement device between the engagement devices to be replaced is compared with the case where the vehicle is not stopped on the uphill road. It is characterized in that the torque transfer of the tie-up is controlled to the tie-up side.

  In this way, on the uphill road, the torque transfer between the engagement devices is controlled to the tie-up side, so that the force in the locking direction acts on the rotating member in the automatic transmission, thereby suppressing the vehicle from sliding down. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram illustrating an example of a vehicle including a drive device to which the present invention is applied, and a diagram illustrating a main part of a control system provided in the vehicle. FIG. 2 is a flowchart for explaining a main part of a control operation of the electronic control device of FIG. 1, that is, a control operation for preventing a vehicle from sliding down when starting from a vehicle stop on an uphill road. It is a time chart which shows the oil pressure command value of the friction engagement device on the release side and the friction engagement device on the engagement side during the downshift.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a schematic configuration diagram for explaining an example of a vehicle 10 having a drive device 12 to which the present invention is applied, and a diagram for explaining a main part of a control system provided in the vehicle 10. The drive device 12 includes an engine (ENG) 14, a torque converter (T / C) 16 having a lock-up clutch 26, an automatic transmission (AT) 18, a differential gear device 20, and the like. The power output from 14 is transmitted to the drive wheels 24 via the torque converter 16, the automatic transmission 18, the differential gear device 20, and the left and right axles 22. This drive device 12 is suitably used for an FF vehicle mounted in the left-right direction (horizontal placement) of the vehicle. The engine 14 that is a driving force source is an internal combustion engine such as a gasoline engine or a diesel engine that generates power by combustion of fuel, and the torque converter 16 corresponds to a fluid transmission device.

  The automatic transmission 18 selectively connects a plurality of planetary gear devices (not shown) and rotating members constituting the plurality of planetary gear devices in a transmission case 30 as a non-rotating member attached to the vehicle body. Including a clutch (C1) for turning on and off, and a brake (B1, B2) for selectively connecting and shutting off a predetermined rotating member constituting the planetary gear device to a transmission case 30 which is a non-rotating member. By changing the connection state of these clutches and brakes, for example, the first gear (first gear) “1st” to the sixth gear (sixth gear) “ The speed is changed to a plurality of 6th speed stages. The clutch and the brake are both constituted by a hydraulic friction engagement device, and a so-called clutch-to-clutch shift is performed in which the clutch and the brake are changed in the transition period.

  Such a driving device 12 includes an electronic control device 50 (corresponding to the control device of the present invention) as shown in FIG. The electronic control unit 50 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM, and signals according to a program stored in the ROM in advance. By performing the processing, output control of the engine 14, shift control of the automatic transmission 18, ON / OFF control of the lockup clutch 26, and the like are executed. The electronic control unit 50 is configured separately for engine control, shift control, and the like as necessary.

  The electronic control unit 50 includes an accelerator operation amount signal indicating the accelerator opening amount Acc, which is the operation amount of the accelerator pedal 31 detected by the accelerator opening sensor 32, and the rotation speed of the engine 14 detected by the engine rotation speed sensor 34. A signal representing the engine rotational speed Ne, a throttle valve opening signal representing the opening θth of the electronic throttle valve detected by the throttle valve opening sensor 36, and a turbine shaft (automatic transmission) detected by the turbine rotational speed sensor 38 A vehicle speed corresponding to a rotation speed Nout of the output shaft of the automatic transmission 18 detected by the vehicle speed sensor 40, that is, a vehicle speed V, which is a signal representing a turbine rotation speed Nt (input shaft rotation speed Nin) that is a rotation speed of 18 input shafts). Signal, the operation amount B of the brake pedal 41 corresponding to the brake depression force detected by the brake switch 42 r etc. are supplied respectively.

  Further, the electronic control device 50 supplies fuel to a drive signal to a throttle actuator for operating the opening degree θth of the electronic throttle valve, an ignition signal for instructing the ignition timing of the engine 14, and an intake pipe or a cylinder of the engine 14. Alternatively, an engine control signal Se such as a fuel supply amount signal for controlling the fuel supply amount to the engine 14 by the fuel injection device to be stopped is output. Further, a shift control signal Sc for controlling a linear solenoid valve (not shown) in the hydraulic control circuit 46 for switching the gear position of the automatic transmission 18, and a lockup for driving a solenoid valve (not shown) for controlling the lockup clutch 26. A control signal Sp or the like is output.

  The electronic control device 50 is configured to functionally include an engine output control unit 52, a shift control unit 54, a vehicle stop determination unit 56, a road gradient determination unit 58, a brake pedal force determination unit 60, and a start intention determination unit 62. ing. The engine output control unit 52 controls opening and closing of the electronic throttle valve according to the accelerator opening Acc by a throttle actuator so that the engine output increases as the accelerator opening Acc increases, and also performs fuel injection for fuel injection control. The output control of the engine 14 is executed by controlling the fuel injection amount by the device and controlling the ignition timing by an ignition device such as an igniter for controlling the ignition timing.

  The shift control unit 54 performs shift control, neutral control, and the like of the automatic transmission 18. For example, an actual vehicle speed V and accelerator opening Acc are determined from a preset shift map including the vehicle speed V and accelerator opening Acc. , The shift speed to be shifted is determined, and shift control to that shift speed is executed. The shift control unit 54 releases the frictional engagement device to be released and shifts the torque by engaging the frictional engagement device to be engaged (re-holding the frictional engagement device). A so-called clutch-to-clutch shift is performed.

  In addition, the shift control unit 54 performs downshift control accompanying a decrease in the vehicle speed V during vehicle deceleration by turning off the accelerator pedal 31 or depressing the brake pedal 41. Here, the shift control unit 54 avoids excessive deceleration and shift shock during deceleration, so that the first speed gear stage that is the lowest speed stage (the lowest speed stage) before the vehicle stops (stops). For example, a gear stage other than the first speed gear stage such as the second speed gear stage is established without downshifting. Further, when the shift control unit 54 detects the driver's intention to start based on depression of the accelerator pedal after the vehicle stops (stops), the shift control unit 54 shifts down to the first gear (clutch-to-clutch downshift). By executing the above, the responsiveness and driving force when starting the vehicle are ensured.

  By the way, when the vehicle is decelerated and stopped while traveling on an uphill road, the braking force is smaller than when the vehicle is stopped on a flat road. Further, if the slope of the uphill road becomes tight, the vehicle may be stopped due to the balance with the creep force of the vehicle or the balance by the accelerator operation. A vehicle that does not have a hill hold function to prevent the vehicle from falling down, although a downshift is executed after detecting the driver's intention to start due to depression of the accelerator pedal after stopping the vehicle under such circumstances In this case, torque loss may occur during the downshift, and the vehicle may slip down. Therefore, the electronic control unit 50 prevents slipping during the downshift in the downshift executed at the time of starting on the uphill road by executing the control described later.

  Returning to FIG. 1, the vehicle stop determination unit 56 determines whether or not the vehicle has stopped during vehicle deceleration. The vehicle stop determination unit 56 determines the stop of the vehicle 10 when, for example, the vehicle speed V detected by the vehicle speed sensor 40 decreases to a predetermined value V1 or less. The predetermined value V1 is a value obtained experimentally in advance, and is set to a minute value that can be determined that the vehicle is stopped.

  The road gradient determination unit 58 detects the road gradient δ and determines whether the road gradient δ is an uphill road based on whether the road gradient δ is equal to or greater than a predetermined value δ1. The road gradient δ is detected from, for example, road information from the navigation system or a change in the vehicle speed V immediately before the vehicle stops. The predetermined value Δ1 is experimentally obtained in advance and is set to a threshold value at which the vehicle slips when starting.

  The brake operation determination unit 60 determines whether or not the brake pedal 41 is depressed by the driver when the vehicle is stopped on the uphill road. Depression of the brake pedal 41 is determined based on the operation amount Br of the brake pedal 41 corresponding to the brake depression force detected by the brake switch 42. Further, when it is determined that the brake pedal 41 is depressed, the start intention determination unit 62 determines whether or not the brake depression force is smaller than a predetermined value ε set in advance. The brake pedal force is obtained from the operation amount Br of the brake pedal 41 that has a one-to-one relationship with the brake pedal force.

  When the brake pedal force is smaller than the predetermined value ε, the start intention determination unit 62 determines that the brake pedal force is smaller than a predetermined value γ smaller than the predetermined value ε, for example, and the rate of change of the brake pedal force toward the decrease side is increased. When the predetermined value σ or more set in advance is detected, or when an off operation for releasing the depression of the brake pedal 41 is detected, the driver's intention to start is determined. In other words, the start intention determination unit 62 assumes that the driver intends to start when an operation for releasing the depression of the brake pedal 41 is performed when the brake pedal force is stopped in a state of being smaller than the predetermined value ε. judge. The predetermined values ε and σ are values obtained experimentally in advance, and both are set to threshold values that can determine the driver's intention to start.

  Further, when it is determined that the brake pedal 41 is not depressed based on the brake operation determination unit 60 even when the vehicle is stopped, the start intention determination unit 62 has a predetermined accelerator opening Acc. If it is detected that the value is greater than or equal to α, or the accelerator pedal operation speed (the rate of change of the accelerator opening Acc) is greater than or equal to a preset value β, the driver intends to start Is determined. The predetermined values α and β are values that are experimentally obtained in advance, and both are set to threshold values that can determine the driver's intention to start.

  When the driver's intention to start is determined based on the start intention determination unit 62, the shift control unit 54 determines whether the automatic transmission 18 is downshifted, and is a friction engagement device that is released during the downshift. And the clutch torque capacity of the friction engagement device to be engaged is calculated. Here, the shift control unit 54 changes the torque capacity of the friction engagement device to be released and the friction engagement device to be engaged in accordance with the road gradient δ in order to prevent the downshift during the downshift. Specifically, the clutch torque capacity of the disengagement side friction engagement device and the clutch torque capacity of the engagement side friction engagement device are corrected to the increase side compared to the flat road, and the clutch torque capacity is Correction is made in proportion to the road gradient δ. For example, the shift control unit 54 stores hydraulic command values corresponding to the clutch torque capacities of the disengagement side frictional engagement device and the engagement side frictional engagement device on a flat road, and further according to the road gradient δ. A relationship map for obtaining the pressure increase correction value, and correcting the oil pressure correction value to the pressure increase side by the pressure increase correction value obtained from the relationship map.

  When the clutch torque capacity of each friction engagement device is corrected to increase, the torque is transferred from the release-side friction engagement device constituting the automatic transmission 18 to the engagement-side friction engagement device. It is controlled to a tie-up state that is not performed smoothly, and an internal lock state is applied, in which a force in a direction to stop (lock) rotation of the rotating member constituting the automatic transmission 18 is applied. Therefore, it is possible to start without the vehicle 10 sliding down during the downshift. Further, since the clutch torque capacity increases in proportion to the road gradient δ, the force that locks the rotating member of the automatic transmission 18 increases as the road gradient becomes steeper. 10 sliding down is prevented. Further, since the frictional engagement device on the engagement side is controlled to a tie-up state, engine speed increase due to torque loss during a downshift and a shift shock are also suppressed.

  If the road gradient determining unit 58 determines that the stopped road is not an uphill road, the shift control unit 54 performs a downshift after the vehicle stops. Further, even when the vehicle is stopped on an uphill road, if the brake pedal force is equal to or greater than the predetermined value ε, the shift control unit 54 performs a downshift after the vehicle stops.

  FIG. 2 is a flowchart for explaining a main part of the control operation of the electronic control unit 50, that is, a control operation for preventing the vehicle 10 from sliding down when starting from a vehicle stop on an uphill road. This flowchart is repeatedly executed with an extremely short cycle time of, for example, about several milliseconds to several tens of milliseconds.

  First, when the vehicle is decelerated at a high gear (for example, the second gear) in step S1 (hereinafter, step is omitted), the vehicle 10 is moved based on the vehicle speed V in S2 corresponding to the vehicle stop determination unit 56. It is determined whether or not the vehicle is stopped. When the vehicle speed V is higher than the predetermined value V1, S2 is denied, and the process returns to S1 and the vehicle is continuously decelerated. When the vehicle speed V becomes equal to or less than the predetermined value V1, it is determined that the vehicle has stopped, and the process proceeds to S3. In S3 corresponding to the road gradient determination unit 56, it is determined whether or not the road is an uphill road based on whether or not the road gradient δ is greater than or equal to a predetermined value δ1. If the road gradient δ is less than the predetermined value δ1, it is determined that the stopped road is not an uphill road, and the process proceeds to S8. If the road gradient δ is greater than or equal to the predetermined value δ1, it is determined that the stopped road is an uphill road, and the process proceeds to S4.

  In S4 corresponding to the brake operation determination unit 60, it is determined whether or not the driver has depressed the brake pedal 41 (brake-on operation). When the brake pedal 41 is depressed, the process proceeds to S5, and when the brake pedal 41 is not depressed, the process proceeds to S7. In S5 corresponding to the brake operation determination unit 60, it is determined whether or not the brake pedal force is smaller than a predetermined value ε. If the brake pedal force is smaller than the predetermined value ε, the process proceeds to S6, and if the brake pedal force is greater than the predetermined value ε, the process proceeds to S8.

  In S6 corresponding to the start intention determination unit 62, the brake pedal force has become smaller than the predetermined value γ, the speed of change of the brake pedal force to the decreasing side has become the predetermined value σ or more, or the brake pedal 41 has been depressed. When an off operation for releasing is detected, it is determined that the driver intends to start, and the process proceeds to S8.

  If it returns to S4 and it determines with the brake pedal 41 not being depressed, in S7 corresponding to the start intention determination part 62, the accelerator opening Acc is more than predetermined value (alpha), or the operating speed of an accelerator pedal is set. If it is determined that the value is equal to or greater than the predetermined value β, it is determined that the driver intends to start and the process proceeds to S8.

  In S8 corresponding to the shift control unit 54, it is determined to switch to a low gear (for example, the first gear). In S9 corresponding to the shift control unit 54, the clutch torque capacity (actually, the hydraulic pressure command value) of the disengagement friction engagement device and the clutch torque capacity of the engagement friction engagement device corresponding to the road gradient δ. Is calculated and a downshift is performed. At this time, the torque capacity of each friction engagement device is controlled in a tie-up state as compared with a flat road, and the rotating member of the automatic transmission 18 is in an internal lock state, thereby preventing the vehicle from sliding down during a downshift. The In S10 corresponding to the shift control unit 58, the vehicle is started at the gear stage (shift stage) after the downshift.

  FIG. 3 is a time chart showing hydraulic pressure command values of the disengagement side frictional engagement device C2 and the engagement side frictional engagement device C1 during the downshift. In the time chart of FIG. 3, the horizontal axis indicates the elapsed time, and the vertical axis indicates the hydraulic pressure command value to the disengagement side and engagement side friction engagement devices. Further, the solid line indicates the normal time (flat road), and the broken line indicates the uphill time.

  Explaining the normal time indicated by the solid line (when the flat road is stopped), when a downshift command is output at time t1, the hydraulic pressure of the clutch C2, which is the friction engagement device on the disengagement side, is suddenly reduced to a predetermined value. The pressure is gradually decreased at a predetermined gradient, and the decrease in hydraulic pressure is completed at time t3. Further, when a downshift command is output at the time t1, the clutch C1, which is a friction engagement device on the engagement side, is suddenly raised to a predetermined hydraulic pressure and held at that hydraulic pressure for a predetermined time, and then the hydraulic pressure is temporarily increased. Is pulled down and held (quick apply). When the time point t2 is reached, the hydraulic pressure of the clutch C1 is gradually increased, and at the time point t3, the increase in the hydraulic pressure is finished. In this normal downshift, torque is delivered optimally, and the internal lock of the automatic transmission 18 does not occur.

  Next, a downshift on an uphill road indicated by a broken line will be described. On the uphill road, the hydraulic pressure command values of the clutch C1 and the clutch C2 are corrected to the pressure increasing side according to the road gradient δ. For example, as shown in FIG. 3, the hydraulic pressure of the clutch C1 is increased by a predetermined value compared to the normal time indicated by the solid line. Further, the hydraulic pressure of the clutch C2 is increased by a predetermined value compared to the normal time indicated by the solid line. In this connection, since the automatic transmission 18 is in the internal lock state, the vehicle is prevented from slipping during the downshift.

  As described above, according to this embodiment, on the uphill road, the torque transfer between the engagement devices is controlled to the tie-up side, so that the force in the locking direction acts on the rotating member in the automatic transmission 18. Therefore, the vehicle can be prevented from sliding down.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the downshift is not limited to a shift to a specific gear stage. For example, a downshift from a third speed gear stage to a first speed gear stage is performed. If so, it is applicable.

  In the above-described embodiment, after step S5 of the flowchart of FIG. 2 is established (the brake pedal force is less than the predetermined value ε), the accelerator pedal is depressed with the brake pedal 41 being depressed (accelerator pedal and For the simultaneous depression of the brake pedal, the process can proceed to step S7 to execute the control after step S7.

  In the above-described embodiment, the connection configuration of the automatic transmission 18 is not particularly limited, and can be freely changed.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

10: Vehicle 18: Automatic transmission (automatic transmission for vehicle)
50: Electronic control device C1, C2: Clutch (friction engagement device)

Claims (1)

In a vehicle equipped with a stepped vehicle automatic transmission capable of shifting in multiple stages by changing the engagement device, the vehicle is stopped at a speed other than the lowest speed of the automatic transmission. A control device for an automatic transmission for a vehicle that performs downshift by re-engaging the engagement device when detecting the driver's intention to start,
When performing a downshift while the vehicle is stopped on an uphill road, compared to when the vehicle is not stopped on an uphill road, the torque transfer between the engaging devices to be gripped is controlled to the tie-up side. A control device for an automatic transmission for a vehicle.

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