JP5181612B2 - Control device for automatic transmission - Google Patents

Description

  The present invention relates to a control device for an automatic transmission mounted on a vehicle.

  In a vehicle equipped with an engine (internal combustion period), the gear ratio between the engine and the drive wheels is automatically used as a transmission that appropriately transmits the torque and rotation speed generated by the engine to the drive wheels according to the running state of the vehicle. Automatic transmissions that are optimally set are known.

  As an automatic transmission mounted on a vehicle, for example, a planetary gear type transmission that sets a gear stage using a clutch and brake and a planetary gear device, or a belt type that adjusts a gear ratio steplessly. There is a continuously variable transmission (CVT).

  In a vehicle equipped with a planetary gear type automatic transmission, a shift map having a shift line (shift stage switching line) for obtaining an optimum shift stage according to the vehicle speed and the accelerator opening (or throttle opening). Is stored in an ECU (Electronic Control Unit) or the like, a target shift speed is calculated with reference to a shift map based on the vehicle speed and the accelerator opening, and a clutch that is a friction engagement element is calculated based on the target shift speed. The gear position is automatically set by engaging or releasing the brake and the one-way clutch in a predetermined state.

  A vehicle equipped with such an automatic transmission is provided with a shift lever operated by a driver, and by operating the shift lever, the shift position of the automatic transmission is set to, for example, a P position (parking). Range), R position (reverse travel range), N position (neutral range), D position (forward travel range), and the like.

  Further, in a vehicle equipped with an automatic transmission, a road surface friction coefficient (hereinafter referred to as a road surface μ) is detected based on a speed difference between front and rear wheels, a slip ratio of a driving wheel, and the detected road surface μ is less than a predetermined value. In some cases, in order to reduce the driving force, control is performed such that the gear position at the time of starting and stopping is set to the second speed (see, for example, Patent Document 1).

Further, in a vehicle in which the snow mode is set, when the snow mode switch is operated (ON) by the driver, the shift stage at the time of starting is set not to the first speed but to the second speed or more (for example, patent Reference 2).
JP-A-9-249050 Japanese Patent No. 2000-104816 (paragraph [0007]) Japanese Patent No. 2005-76772

  By the way, in an automatic transmission, for example, when a one-way clutch is provided in a first-speed engagement element, reverse rotation of an output shaft (drive wheel) of the automatic transmission is prevented when a gear stage of second speed or higher is formed ( Some are configured to be hill hold).

  In a vehicle equipped with an automatic transmission having such a configuration, as described above, when the road surface μ is low or the snow mode is set, the automatic transmission reversely rotates when stopped at the second gear or higher. Since it becomes impossible, when the vehicle moves backward, a large load (inertia of the vehicle) is applied to the one-way clutch, and the one-way clutch may be damaged.

  The present invention has been made in consideration of such a situation, and in an automatic transmission having a gear stage (second gear stage or higher) in which rotation in the vehicle reverse direction can be prevented by a one-way clutch, gear shifting of two speeds or higher is performed. The purpose is to realize a control capable of protecting the one-way clutch while ensuring the stopping / starting performance at the stage.

The present invention relates to a stepped automatic transmission mounted on a vehicle, and a control device for an automatic transmission having a specific shift stage in which rotation in the vehicle reverse direction can be blocked by a one-way clutch on a low shift stage side. It is assumed. In such a control device for an automatic transmission, when it is determined that there is a possibility of a vehicle retreating, vehicle retraction determining means for determining whether or not there is a possibility of a vehicle retreating, and the vehicle retreat determining means. And a shift speed formation control means for prohibiting the formation of the specific shift speed, and when the vehicle reverse determination means determines that there is a possibility of vehicle reverse, the rotation in the vehicle reverse direction is the first speed. The second speed that can be blocked by the one-way clutch is prohibited and the first speed is formed. After the second speed is prohibited, the second speed is permitted if it is determined that there is no possibility of the vehicle moving backward. It is characterized by that.

Specific examples of the present invention include the following. First, the vehicle reverse determination unit determines that “there is a possibility of vehicle reverse” when the condition “the slope of the road surface is an uphill road” is satisfied.

In addition, the speed change formation control means prohibits the formation of the second speed, and then when the condition of “the brake is ON” or “the road surface has a non-climbing slope” is satisfied (possible to reverse the vehicle) The second speed is permitted when there is no property.

  According to the present invention, it is determined whether or not there is a possibility of the vehicle retreating, and when the vehicle is in a situation of retreating, the formation of the second speed as a hill hold is prohibited. It is possible to prevent the one-way clutch from being damaged. In addition, when the vehicle is not likely to move backward, the second speed formation is permitted, so that the stopping / starting performance of the vehicle in a situation where the road surface μ is low can be ensured.

In this case, when the 1-> 2 shift is performed by allowing the 2-speed formation from the state where the 2-speed formation is prohibited and the 1-speed is formed, if the vehicle speed is 0, the 1-> 2 shift is performed. It controls based on the elapsed time from 2nd speed formation permission . Specifically, using a counter that measures the elapsed time from the 2nd speed formation permission (1 → 2 shift start), when the vehicle speed when performing the 1 → 2 shift is 0 (vehicle stop), When the time measured by the counter reaches a predetermined determination value (specifically, a value considering the time required for 1 → 2 shift when the vehicle is stopped), the 1 → 2 shift is ended. Execute control.

  If such a configuration is adopted, 1 → 2 shift control when the vehicle is stopped (2nd speed prohibition → control when permitted) without performing complicated processing such as newly setting the hydraulic pressure instruction value of the automatic transmission. ) Can be realized with a simple configuration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A power train of a vehicle including the control device of the present invention will be described with reference to FIGS.

  The power train of the vehicle in this example includes an engine 1, an automatic transmission 2, an engine ECU 3, and an ECT_ECU (Electronic Controlled Automatic Transmission_ECU) 5, and the automatic transmission 2 according to a program executed by the ECT_ECU 5. The control device is realized.

  Next, each part of the engine 1, the automatic transmission 2, the engine ECU 3, and the ECT_ECU 5 will be described below.

-Engine-
The engine 1 generates rotational power by burning an air-fuel mixture in which air sucked from outside and fuel injected from an injector (fuel injection valve) 11 are mixed at an appropriate ratio. The injector 11 is controlled by the engine ECU 3. A crankshaft 8 that is an output shaft of the engine 1 is connected to an input shaft of the torque converter 20. The rotation speed (engine rotation speed) of the crankshaft 8 is detected by an engine rotation speed sensor 91.

  The amount of air taken into the engine 1 is adjusted by an electronically controlled throttle valve 12. The throttle valve 12 can electronically control the throttle opening independently of the driver's accelerator pedal operation, and the opening (throttle opening) is detected by a throttle opening sensor 96.

  The throttle opening of the throttle valve 12 is driven and controlled by the engine ECU 3. Specifically, the optimum intake air amount (target intake air amount) according to the operating state of the engine 1, such as the engine speed detected by the engine speed sensor 91, the accelerator pedal depression amount (accelerator opening) of the driver, and the like. Is controlled so that the throttle opening of the throttle valve 12 is obtained. More specifically, the actual throttle opening of the throttle valve 12 is detected using the throttle opening sensor 96, and the actual throttle opening coincides with the throttle opening (target throttle opening) at which the target intake air amount can be obtained. Thus, the throttle motor 13 of the throttle valve 12 is feedback-controlled.

-Automatic transmission-
The automatic transmission 2 includes a torque converter 20, a transmission mechanism 30, a hydraulic control circuit 40, an oil pump 60, and the like. In this example, the automatic transmission 2 is capable of shifting eight forward speeds and one reverse speed.

  The torque converter 20 is rotationally connected to the crankshaft 8 of the engine 1. As shown in FIG. 2, the torque converter 20 includes a pump impeller 21, a turbine runner 22, a stator 23, a one-way clutch 24, a stator shaft 25, a lock-up clutch 26, and the like.

  The one-way clutch 24 is supported by allowing the stator 23 to rotate only in one direction on the case 2 a of the automatic transmission 2. The stator shaft 25 fixes the inner race of the one-way clutch 24 to the case 2a of the automatic transmission 2. The lock-up clutch 26 enables the pump impeller 21 of the torque converter 20 and the turbine runner 22 to be directly connected. If necessary, the lock-up clutch 26 directly engages the pump impeller 21 and the turbine runner 22, and the pump impeller. 21 is switched to a disengaged state in which the turbine runner 22 and the turbine runner 22 are separated, and a half-engaged state intermediate between the engaged state and the disengaged state.

  The speed change mechanism 30 changes the rotational power input to the input shaft 9 from the torque converter 20 and outputs it to the output shaft 10, and as shown in FIGS. 2 and 3, the front planetary 31 and the rear planetary 32, an intermediate drum 33, a first clutch (input clutch) C1, a second clutch C2, a third clutch C3, a fourth clutch C4, a first brake B1, a second brake B2, and a one-way clutch F1. .

  The front planetary 31 is a double pinion type gear planetary mechanism, and includes a first sun gear S1, a first ring gear R1, a plurality of inner pinion gears P1, a plurality of outer pinion gears P2, and a first carrier CA1. It has.

  The first sun gear S1 is fixed to the case 2a of the automatic transmission 2 and cannot be rotated, and the first ring gear R1 can be rotated integrally with the intermediate drum 33 via the third clutch C3 or can be relatively rotated. The first sun gear S1 is concentrically inserted on the inner diameter side of the first ring gear R1.

  The plurality of inner pinion gears P1 and the plurality of outer pinion gears P2 are interposed at a plurality of circumferential locations in the opposed annular space between the first sun gear S1 and the first ring gear R1, and the plurality of inner pinion gears P1 is the first inner gear P1. The plurality of outer pinion gears P2 mesh with the sun gear S1, and the plurality of outer pinion gears P2 mesh with the inner pinion gear P1 and the first ring gear R1.

  The first carrier CA1 rotatably supports both pinion gears P1, P2, and the central shaft portion of the first carrier CA1 is integrally connected to the input shaft 9, and both pinion gears P1, P1 are connected to the first carrier CA1. Each support shaft portion that supports P2 is supported by the intermediate drum 33 via the fourth clutch C4 so as to be integrally rotatable or relatively rotatable. The intermediate drum 33 is rotatably arranged on the outer diameter side of the first ring gear R1, and is supported by the case 2a of the automatic transmission 2 in a non-rotatable state or a relatively rotatable state via the first brake B1. Has been.

  The rear planetary 32 is a Ravigneaux type geared planetary mechanism, and includes a large-diameter second sun gear S2, a small-diameter third sun gear S3, a second ring gear R2, a plurality of short pinion gears P3, and a plurality of long pins. The pinion gear P4 and the second carrier CA2 are included. The second sun gear S2 is connected to the intermediate drum 33, and the third sun gear S3 is connected to the first ring gear R1 of the front planetary 31 via the first clutch C1 so as to be integrally rotatable or relatively rotatable, and the second ring gear R2 Is integrally connected to the output shaft 10.

  The plurality of short pinion gears P3 mesh with the third sun gear S3, and the plurality of long pinion gears P4 mesh with the second sun gear S2 and the second ring gear R2, and the third sun gear S3 via the short pinion gear P3. Are engaged. The second carrier CA2 rotatably supports both pinion gears P3 and P4. The central shaft portion of the second carrier CA2 is coupled to the input shaft 9 via the second clutch C2, and the second carrier CA2 Support shaft portions that support both pinion gears P3 and P4 are supported by case 2a of automatic transmission 2 via second brake B2 and one-way clutch F1.

  The first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, and the second brake B2 are wet multi-plate friction engagement devices that use the viscosity of oil. ing.

  The 1st clutch C1 makes the 3rd sun gear S3 of the rear planetary 32 the engagement state which can be rotated integrally with respect to the 1st ring gear R1 of the front planetary 31, or the releasing state which can be rotated relatively. The second clutch C <b> 2 sets the second carrier CA <b> 2 of the rear planetary 32 in an engaged state in which the second carrier CA <b> 2 can rotate integrally with the input shaft 9 or a released state in which relative rotation is possible.

  The third clutch C3 is configured to bring the first ring gear R1 of the front planetary 31 into an engaged state in which the first ring gear R1 can rotate integrally with the intermediate drum 33 or a released state in which relative rotation is possible. The fourth clutch C <b> 4 sets the first carrier CA <b> 1 of the front planetary 31 to an engaged state where the first carrier CA <b> 1 can rotate integrally with the intermediate drum 33 or a released state which allows relative rotation.

  The first brake B1 integrates the intermediate drum 33 with the case 2a of the automatic transmission 2 so as to be in a non-rotatable engaged state or a relatively rotatable disengaged state. The second brake B2 integrates the second carrier CA2 of the rear planetary 32 with respect to the case 2a of the automatic transmission 2 so as to be in a non-rotatable engaged state or a relatively rotatable disengaged state.

  Further, the one-way clutch F1 allows rotation of the rear planetary 32 in only one direction of the second carrier CA2.

  Here, conditions for establishing the respective shift speeds (first speed to eighth speed, reverse speed) in the automatic transmission 2 will be described with reference to FIGS. 4 and 5.

  FIG. 4 shows the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, the second brake B2, and the one-way clutch F1 in the engaged state or the released state and the respective shift stages. It is an engagement table | surface (operation table | surface) which shows the relationship. In FIG. 4, “◯” indicates “engaged state”, “×” indicates “released state”, “◎” indicates “engaged state during engine braking”, and Δ indicates “engaged state only during driving”.

  FIG. 5 shows a shift speed (first gear) established by engagement of the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, the second brake B2, and the one-way clutch F1. It is a speed diagram which shows the relationship between the rotation speed ratio of each component in two planetary 31 and 32 before and behind at that time (1st speed-8th speed, reverse speed).

  In FIG. 5, each vertical axis direction is the speed ratio of each component in the two planetaries 31 and 32, and the interval between the vertical axes is set according to the gear ratio of each element. Further, the points where the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, the second brake B2, and the one-way clutch F1 are engaged are respectively C1, C2 , C3, C4, B1, B2, and F1 are entered. Further, the input 1 to the input 4 shown in FIG. 5 indicate the input position of the rotational power from the input shaft 9, and the output shown in FIG. The output position of power is shown.

  4 and 5, in the automatic transmission 2 of this example, when the first clutch C1 is engaged, the first forward speed (1st) is established, and at this first speed, the one-way clutch F1 is engaged. Engage. When the first clutch C1 and the first brake B1 are engaged, the second forward speed (2nd) is established. When the first clutch C1 and the third clutch C3 are engaged, the third forward speed (3rd) is established. When the first clutch C1 and the fourth clutch C4 are engaged, the fourth forward speed (4th) is established.

  Further, when the first clutch C1 and the second clutch C2 are engaged, the fifth forward speed (5th) is established. When the second clutch C2 and the fourth clutch C4 are engaged, a forward gear 6 (6th) is established. When the second clutch C2 and the third clutch C3 are engaged, a forward gear 7 (7th) is established. When the second clutch C2 and the first brake B1 are engaged, the forward gear 8 (8th) is established. On the other hand, when the fourth clutch C4 and the second brake B2 are engaged, the reverse speed (R) is established.

  As described above, in the automatic transmission 2 of this example, the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, the second brake B2, which are friction engagement elements, Further, the gear (gear) is set by engaging or releasing the one-way clutch F1 or the like in a predetermined state. Engagement / release of the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, and the second brake B2 is controlled by the hydraulic control circuit 40 and the ECT_ECU5.

  The hydraulic control circuit 40 controls the speed change operation of the speed change mechanism unit 30 and includes a linear solenoid valve, an ON-OFF solenoid valve, an accumulator, and the like. The linear solenoid valve and the ON-OFF solenoid valve By switching the hydraulic circuit by controlling excitation / non-excitation, the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, and the second brake of the speed change mechanism 30. The engagement / release of B2 is controlled. Excitation / non-excitation of the linear solenoid valve and the ON-OFF solenoid valve of the hydraulic control circuit 40 is controlled by a solenoid control signal (instructed hydraulic signal) from the ECT_ECU 5.

  On the other hand, a shift device 7 as shown in FIG. 6 is arranged near the driver's seat of the vehicle. The shift device 71 is provided with a shift lever 71 so that it can be displaced. The shift device 7 is set with an R position (reverse range), an N position (neutral range), a D position (drive range), and an S position (sequential range). The shift lever 71 can be displaced. Each shift position (range) of these R position, N position, D position, and S position (including the following “+” position and “−” position) is detected by a shift position sensor 94.

  Then, regarding the situation where the shift position of the shift lever 71 is selected and the operation state of the automatic transmission 2 at that time, the respective shift positions (“N position”, “R position”, “D position”, “S position”). ).

  The “N position” is a position selected when the connection between the input shaft 9 and the output shaft 10 of the automatic transmission 2 is disconnected. When the shift lever 71 is operated to this “N position”, the automatic transmission All of the first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, and the second brake B2 of the machine 2 are released (see FIG. 4).

  The “R position” is a position selected when the vehicle is moved backward. When the shift lever 71 is operated to the R position, the automatic transmission 2 is switched to the reverse gear.

  The “D position” is a position selected when the vehicle moves forward. When the shift lever 71 is operated to the D position, a plurality of forward shifts of the automatic transmission 2 are performed according to the driving state of the vehicle. The speed of the stage (eight speed forward) is automatically controlled.

  The “S position” is a position that is selected when traveling in the sequential mode (manual mode), that is, when the driver manually performs a shift operation of a plurality of forward shift speeds (forward 8 speeds), A “−” position and a “+” position are provided before and after the S position. The “+” position is a position where the shift lever 71 is operated during an upshift in the sequential mode, and the “−” position is a position where the shift lever 71 is operated during a downshift in the sequential mode.

  When the shift lever 71 is in the S position and the shift lever 71 is operated to the “+” position or the “−” position with the S position as a neutral position, the forward shift speed of the automatic transmission 2 is increased or decreased. Is done. Specifically, the gear position is increased by one step for each operation to the “+” position (for example, 1st → 2nd →... → 8th). On the other hand, each time the operation to the “−” position is performed, the gear position is decreased by one step (for example, 8th → 7th →... → 1st).

-Engine ECU / ECT_ECU-
The engine ECU 3 and the ECT_ECU 5 are electronic control units mainly composed of a microcomputer, and both have almost the same hardware configuration. Here, a specific configuration of the ECT_ECU 5 is shown in FIG.

  The ECT_ECU 5 establishes an appropriate shift stage, that is, a power transmission path in the transmission mechanism unit 30 by controlling the hydraulic control circuit 40. That is, as shown in FIG. 7, the ECT_ECU 5 includes a CPU (Central Processing Unit) 51, a ROM (Read Only Memory) 52, a RAM (Random Access Memory) 53, a backup RAM 54, an input interface 55, and an output interface. 56 are connected to each other by a bidirectional bus 57.

  The CPU 51 executes arithmetic processing based on various control programs and control maps stored in the ROM 52. The ROM 52 stores various control programs for controlling the speed change operation of the speed change mechanism 30. The RAM 53 is a memory that temporarily stores calculation results in the CPU 51, data input from each sensor, and the like. The backup RAM 54 is a non-volatile memory that stores various data to be saved.

  The input interface 55 includes an engine speed sensor 91, a turbine speed sensor 92, an output shaft speed sensor 93, a shift position sensor 94, an accelerator opening sensor 95, a throttle opening sensor 96, a vehicle speed sensor 97, a G sensor (pendulum). Equation) 98, a brake pedal sensor 99, a brake pressure sensor 101, and the like are connected, and signals from these sensors are input to the ECT_ECU 5. The output interface 56 is connected to a hydraulic control circuit 40 that controls the automatic transmission 2.

  The turbine speed sensor 92 detects the turbine speed Nt of the torque converter 20 (the speed of the input shaft 9). The output shaft rotational speed sensor 93 detects the rotational speed of the output shaft 10 (output shaft rotational speed Nout).

  The shift position sensor 94 detects the operation position (neutral range, travel range, etc.) of the shift lever 71 as described above. The accelerator opening sensor 95 detects the amount of depression of the accelerator pedal (accelerator opening) by the driver.

  The vehicle speed sensor 97 detects the traveling speed of the vehicle. The G sensor 98 detects accelerations in the front / rear and left / right directions of the vehicle. In this example, since the pendulum G sensor 98 is used, the gradient of the road surface on which the vehicle travels can be detected. The brake pedal sensor 99 outputs a brake ON signal when the brake pedal is turned on (braking operation) by the driver. The brake pressure sensor 101 detects the hydraulic pressure of the brake master cylinder.

  The ECT_ECU 5 is connected to the engine ECU 3 in a state where data communication is possible, and acquires various information related to engine control from the engine ECU 3 as necessary.

  Then, the ECT_ECU 5 outputs a solenoid control signal (hydraulic command signal) for setting the gear position of the automatic transmission 2 to the hydraulic control circuit 40. On the basis of this solenoid control signal, the excitation / non-excitation of the linear solenoid valve and the ON-OFF solenoid valve of the hydraulic control circuit 40 is controlled so as to constitute a predetermined shift speed (1st to 8th). The first clutch C1, the second clutch C2, the third clutch C3, the fourth clutch C4, the first brake B1, the second brake B2, and the one-way clutch F1 of the automatic transmission 2 are engaged in a predetermined state or To be released.

  Further, the ECT_ECU 5 outputs a lockup clutch control signal (hydraulic command signal) to the hydraulic control circuit 40. On the basis of this lockup clutch control signal, excitation / non-excitation of the lockup solenoid valve of the hydraulic control circuit 40 is controlled, and the lockup clutch 26 of the torque converter 20 is engaged or released.

  Next, “shift control” and “second-speed formation prohibition / permission control” executed by the ECT_ECU 5 will be described.

-Shift control-
First, a shift map used for shift control of the automatic transmission 2 will be described with reference to FIG.

  The shift map shown in FIG. 8 uses a vehicle speed and an accelerator opening as parameters, and a plurality of areas for determining an appropriate shift speed (a shift speed that provides optimum fuel consumption) is set according to the vehicle speed and the accelerator opening. Map. The shift map is stored in the ROM 52 of the ECT_ECU 5. Each region of the shift map is partitioned by a plurality of shift lines (shift stage switching lines). In FIG. 8, the upshift line (shift line) is indicated by a solid line, and the downshift line (shift line) is indicated by a broken line. In addition, each switching direction of upshifting and downshifting is indicated using numerals and arrows in the figure.

  Next, the basic operation of the shift control will be described.

  The ECT_ECU 5 calculates the vehicle speed from the output signal of the vehicle speed sensor 97 (or the output signal of the output shaft speed sensor 93), calculates the accelerator opening from the output signal of the accelerator opening sensor 95, and determines the vehicle speed and the accelerator opening. Based on this, the target shift speed is calculated with reference to the shift map of FIG. 8, and the target shift speed is compared with the current shift speed to determine whether or not a shift operation is necessary. As a result of the determination, when a shift operation is not necessary (when the target shift stage and the current shift stage are the same and the shift stage is set appropriately), a solenoid control signal (for maintaining the current shift stage) ( Command hydraulic signal) is output to the hydraulic control circuit 40 of the automatic transmission 2.

  On the other hand, when the target shift speed is different from the current shift speed, a shift operation is performed. For example, when the traveling state of the vehicle changes from the state where the automatic transmission 2 is traveling in the state of “5-speed”, for example, when the vehicle changes from point PA to point PB in FIG. The target shift speed calculated from the shift map is “4th speed”, and the solenoid control signal (instruction hydraulic pressure signal) for setting the 4th speed shift stage is automatically transmitted. 2 is output to the hydraulic control circuit 40 and shifts from the fifth gear to the fourth gear (5 → 4 downshift).

-Prohibition / permission control of speed formation-
First, in a vehicle equipped with an automatic transmission, as described above, the road surface μ is detected based on the speed difference between the front and rear wheels, the slip ratio of the drive wheels, and the detected road surface μ is lower than a predetermined determination value. In this case, in order to reduce the driving force, control is performed in which the gear position at the time of starting and stopping is set to the second speed. Further, in the vehicle in which the snow mode is set, when the snow mode switch is operated (ON) by the driver, the speed stage at the time of starting is set not to the first speed but to the second speed or more. However, if the control always stops at the second speed by the control (second speed formation mode), the automatic transmission cannot be rotated in the reverse direction, and the one-way clutch may be damaged.

  This point will be specifically described. As shown in FIGS. 4 and 5, when the second speed is formed in the automatic transmission 2 of this example, the first clutch C1 and the first brake B1 are engaged. When the vehicle moves backward (the output shaft 10 rotates in the reverse direction) from the second speed formation state, the reverse rotation of the automatic transmission 2 is prevented (hill-held) by the one-way clutch F1 engaged at the first speed. A large load (inertia of the vehicle) is applied, and the one-way clutch F1 may be damaged.

  Therefore, in this example, it is determined whether or not there is a possibility of the vehicle retreating, and when the vehicle is in a situation of retreating, the second speed formation that is a hill hold is prohibited, and the vehicle is not reversible. It is characterized in that second speed formation is permitted.

  An example of the specific control will be described with reference to the flowchart of FIG. The control routine of FIG. 9 is executed in the ECT_ECU 5.

  In step ST1, it is determined whether or not the current control is the second speed formation mode. If the determination result of step ST1 is affirmative, the process proceeds to step ST2. If the determination result in step ST1 is negative, the determination process in step ST1 is repeated until the second speed formation mode is established (until a positive determination is obtained).

  In this example, for example, when the road surface μ calculated based on the speed difference between the front and rear wheels, the slip ratio of the drive wheels, or the like is lower than a predetermined determination value, it is determined that the “second speed formation mode is set”. Further, when a snow mode switch (not shown) is provided, it is determined that “the 2-speed formation mode is in effect” when the snow mode switch is operated to be ON.

In step ST2, it is determined whether or not there is a possibility of vehicle reverse. Specifically, when the following condition J11 or J12 is satisfied, it is determined that “there is a possibility of vehicle reverse”.

J11 : When the slope of the road surface is an uphill road (determined based on the output signal of the G sensor 98 or navigation information from the navigation device)
J12 : The road gradient (determined based on the output signal of the G sensor 98 or navigation information from the navigation device) and the driving force (the torque determined by the engine 1 generated torque and the second gear ratio) are compared. If it is determined that the climbing performance is insufficient, and if the determination result in step ST2 is affirmative, the process proceeds to step ST3. If the determination result in step ST2 is negative, the determination process in step ST2 is repeated.

  In step ST3, the second speed formation of the automatic transmission 2 is prohibited, and the first speed is formed by engaging the first clutch C1 as shown in FIGS. At the first speed, the reverse rotation of the automatic transmission 2 is prevented by the one-way clutch F1.

Next, in step ST4, it is determined whether or not there is no reverse of the vehicle. Specifically, when any one of the following conditions J21 to J23 is satisfied, it is determined that there is no vehicle reverse.

J21: When the brake is ON (determined by the output signal of the brake pedal sensor 99 or the output signal of the brake pressure sensor 101)
J22 : When the slope of the road surface is a non-uphill road (determined based on the output signal of the G sensor 98 or navigation information from the navigation device)
J23 : The road gradient (determined based on the output signal of the G sensor 98 or the navigation information from the navigation device) and the driving force (the torque generated by the engine 1 and the force determined by the gear ratio of the second gear) are compared. If it is determined that the climbing performance is sufficient, and if the determination result in step ST4 is affirmative, the process proceeds to step ST5. If the determination result in step ST4 is negative, the determination process in step ST4 is repeated.

  In step ST5, 2nd speed formation is permitted and 1 → 2 shift is started. Subsequently, in step ST6, it is determined whether or not the vehicle speed = 0 (brake ON). If the determination result is negative (when the vehicle is traveling), the vehicle speed of the traveling vehicle, that is, the output shaft is determined. Based on the rotational speed (output shaft rotational speed Nout detected by the output shaft rotational speed sensor 93), normal 1 → 2 shift control is executed (step ST7).

  Specifically, when the 1 → 2 shift is started, the hydraulic pressure applied to the brake B1 is increased in a predetermined pattern while the first clutch C1 of the automatic transmission 2 is maintained in the engaged state. In the pressure increasing process of the brake B1, when the turbine rotational speed Nt detected by the turbine rotational speed sensor 92 becomes lower than the virtual turbine rotational speed (output shaft rotational speed Nout × 1st gear ratio), inertia is generated. Phase begins. When the turbine rotation speed Nt reaches the synchronous rotation speed based on the output shaft rotation speed Nout (vehicle speed) and the gear ratio of the second gear after the shift (when the brake B1 is completely engaged), the first to second gear The control of ending the shifting is executed.

  On the other hand, when the vehicle speed is 0 (the vehicle is stopped) (Yes in step ST6), the output shaft speed Nout cannot be detected, so that the shift control as in step ST7 cannot be performed.

  Therefore, in this example, the 1 → 2 shift control is executed based on the time measured by the timer (step ST8). Specifically, the elapsed time from the time point when the second speed formation in step ST5 is permitted (1 → 2 shift start) is measured by a timer, and when the measured time reaches a predetermined determination value, 1 → The second speed shift control is terminated. The determination value set for the measurement time in such shift control is, for example, the time required for normal 1 → 2 shift (engagement of the brake B1) when the vehicle speed = 0 (output shaft rotation speed Nout = 0). The time from the start to the complete engagement) is obtained in advance through experiments, calculations, etc., and the value obtained empirically based on the result is used as the judgment value.

  However, the judgment value (judgment value in the normal state) used for the 1 → 2 shift control in step ST8 is the fail-time shift time (engagement of the brake B1) set at the time of failure such as when the output shaft rotational speed sensor 93 is abnormal The time from the start to the complete engagement) is set to a shorter value so that the 1 → 2 shift at the time of stopping the vehicle can be completed at a timing earlier than that at the time of the failure.

  According to the above control, when the vehicle is moving backward, the formation of the second speed as a hill hold is prohibited, so that the one-way clutch F1 can be prevented from being damaged when the vehicle is stopped on the uphill road. . Further, when there is no possibility that the vehicle will move backward, the second speed formation is permitted, so that it is possible to ensure the stopping / starting performance of the vehicle when the road surface μ is low.

  In addition, when the 1st to 2nd gear shift is performed by allowing the 2nd gear formation when there is no possibility of the vehicle reversing, if the vehicle is stopped (vehicle speed = 0), the predetermined time (determination) Since the control of ending the 1 → 2 shift is performed at the time when the value) has elapsed, a complicated process such as newly setting the hydraulic pressure instruction value of the automatic transmission 2 is not performed and the vehicle is stopped. 1 → 2 shift control (2nd speed prohibition → permission control) can be realized with a simple configuration.

-Other embodiments-
In the above example, the example in which the present invention is applied to the control of the automatic transmission configured to be a hill hold when the second speed is formed is shown, but the present invention is not limited to this, and the third speed (or 3 It can also be applied to the control of an automatic transmission having a hill hold when the speed is higher.

  In the above example, an example in which the present invention is applied to control of an automatic transmission with eight forward shifts has been described. However, the present invention is not limited to this, and other arbitrary shift stages such as, for example, six forward shifts. It can also be applied to control of an automatic transmission.

  In the above example, an example in which the present invention is applied to control of an automatic transmission mounted on an FR (front engine / rear drive) type vehicle has been described. However, the present invention is not limited to this, and the FF (front engine) It can also be applied to control of an automatic transmission mounted on a front drive type vehicle and control of an automatic transmission mounted on a four-wheel drive vehicle.

  An example of the automatic transmission mounted on the FF type vehicle is shown in FIG. FIG. 11 shows an engagement table of the automatic transmission.

  An automatic transmission 500 shown in FIG. 10 includes a torque converter 600 and a transmission mechanism unit 700.

  The torque converter 600 includes a pump impeller 21, a turbine runner 22, a stator 23, a one-way clutch 24, a lock-up clutch 26, and the like, similar to the one shown in FIG.

  The transmission mechanism 700 includes a first transmission unit 701 mainly composed of a single pinion type first planetary gear unit 711, a single pinion type second planetary gear unit 712, and a double pinion type third planetary gear unit 713. Is a planetary gear type multi-stage transmission that has a second transmission unit 702 that is configured mainly on the same axis, shifts the rotation of the input shaft 703, transmits it to the output shaft 704, and outputs it from the output gear 705. The output gear 705 is connected to a differential gear device mounted on the vehicle directly or via a counter shaft.

  The first planetary gear device 711 constituting the first transmission unit 701 includes three rotating elements, a sun gear S11, a carrier CA11, and a ring gear R11, and the sun gear S11 is connected to the input shaft 703. Further, the sun gear S11 is decelerated and rotated with respect to the input shaft 703 using the carrier CA11 as an intermediate output member by fixing the ring gear R11 to the housing 706 via the third brake B3.

  In the second planetary gear device 712 and the third planetary gear device 713 constituting the second transmission unit 702, four rotating elements RM11 to RM14 are configured by being partially connected to each other.

  Specifically, the first rotating element RM11 is configured by the sun gear S13 of the third planetary gear unit 713, and the ring gear R12 of the second planetary gear unit 712 and the ring gear R13 of the third planetary gear unit 713 are connected to each other. A second rotation element RM12 is configured. Furthermore, the carrier CA12 of the second planetary gear device 712 and the carrier CA13 of the third planetary gear device 713 are connected to each other to constitute a third rotating element RM13. The fourth rotating element RM14 is configured by the sun gear S12 of the second planetary gear device 712.

  In the second planetary gear device 712 and the third planetary gear device 713, the carriers CA12 and CA13 are configured by a common member, and the ring gears R12 and R13 are configured by a common member. Further, the pinion gear of the second planetary gear device 712 is a Ravigneaux type planetary gear train that also serves as the second pinion gear of the third planetary gear device 713.

  The first rotating element RM11 (sun gear S13) is integrally connected to the carrier CA11 of the first planetary gear device 711 that is an intermediate output member, and is selectively connected to the housing 706 by the first brake B1 to stop rotation. Is done. The second rotating element RM12 (ring gears R12 and R13) is selectively connected to the input shaft 703 via the second clutch C2, and is selectively connected to the housing 706 via the one-way clutch F1 and the second brake B2. The rotation is stopped.

  The third rotation element RM13 (carriers CA12 and CA13) is integrally connected to the output shaft 704. The fourth rotation element RM14 (sun gear S12) is selectively coupled to the input shaft 703 via the first clutch C1.

  Note that. Each of the first clutch C1, the second clutch C2, the first brake B1, the second brake B2, and the third brake B3 is a multi-plate hydraulic friction engagement device that frictionally engages with a hydraulic cylinder.

  In the automatic transmission 2 described above, the first clutch C1, the second clutch C2, the first brake B1, the second brake B2, the third brake B3, and the one-way clutch F1, which are friction engagement elements, are in a predetermined state. The gear position is set by being engaged or released.

  FIG. 11 is an engagement table for explaining the engagement operation of the clutch and the brake for establishing the respective shift stages of the automatic transmission 500 described above, where “◯” indicates engagement and “×” indicates release. Represents.

  As shown in FIG. 11, in the automatic transmission 500 of this example, when the clutch C1 is engaged, the first forward speed (1st) is established, and at this first speed, the one-way clutch F1 is engaged. When the first clutch C1 and the brake B1 are engaged, the second forward speed (2nd) is established. When the first clutch C1 and the third brake B3 are engaged, the third forward speed (3rd) is established.

  Further, when the first clutch C1 and the second clutch C2 are engaged, the fourth forward speed (4th) is established. When the second clutch C2 and the third brake B3 are engaged, the fifth forward speed (5th) is established. When the second clutch C2 and the first brake B1 are engaged, a forward gear 6 (6th) is established. On the other hand, when the second brake B2 and the third brake B3 are engaged, the reverse speed (R) is established.

  The above-described automatic transmission 500 shown in FIG. 10 is also a transmission configured to prevent reverse rotation of the automatic transmission (hill hold) by the one-way clutch F1 engaged at the first speed when the second speed is formed. The one-way clutch F1 is subjected to a large load (inertia of the vehicle) during the hill hold, and the one-way clutch F1 may be damaged. Even in the automatic transmission 500 having such a configuration, the two-speed formation shown in FIG. 9 is prohibited. By executing the permission control, it is possible to prevent the one-way clutch F1 from being damaged when stopping on an uphill road while securing stop / start performance in a situation where the road surface μ is low.

  In the above example, the example in which the present invention is applied to the control of a vehicle equipped with a gasoline engine has been shown. Applicable.

It is a schematic block diagram of the vehicle carrying the automatic transmission to which this invention is applied. It is a skeleton figure which shows an example of an automatic transmission. It is a perspective view which shows typically the transmission mechanism part of an automatic transmission. It is a figure which shows the engagement state for every gear stage of each clutch and each brake in the transmission mechanism part of the automatic transmission of FIG. It is a speed diagram which shows the rotation speed ratio of each component in each planetary of the transmission mechanism part of an automatic transmission for every gear stage. It is a perspective view which shows the structure of the shift lever part of a shift apparatus. It is a block diagram which shows the structure of control systems, such as ECT_ECU. It is a figure which shows an example of the shift map used for the shift control of an automatic transmission. It is a flowchart which shows an example of the control routine of 2nd speed formation prohibition and permission control of an automatic transmission. It is a skeleton figure which shows the other example of an automatic transmission. It is a figure which shows the engagement state for every gear stage of each clutch and each brake in the transmission mechanism part of the automatic transmission of FIG.

Explanation of symbols

1 Engine 2 Automatic transmission 3 Engine ECU
5 ECT_ECU
30 transmission mechanism C1-C4 clutch B1, B2 brake F1 one-way clutch 40 hydraulic control circuit 94 shift position sensor 98 G sensor 99 brake pedal sensor

Claims (5)

In a stepped automatic transmission mounted on a vehicle, a control device for an automatic transmission having a specific shift stage in which rotation in the vehicle reverse direction can be blocked by a one-way clutch on a low shift stage side,
The vehicle reverse determination means for determining whether or not there is a possibility of vehicle reverse, and the formation of the specific shift stage is prohibited when the vehicle reverse determination means determines that there is a possibility of vehicle reverse. Shift stage formation control means ,
If it is determined by the vehicle reverse determination means that “the vehicle is likely to reverse”, the first speed is set by prohibiting the formation of the second speed in which the rotation in the vehicle reverse direction can be prevented by the first speed one-way clutch. formed, after prohibiting the formation of the second speed, the control device of the automatic transmission if it is determined that "there is no possibility of the vehicle back" characterized that you allow the formation of 2-speed. The control device for an automatic transmission according to claim 1,
When the 1st to 2nd shift is performed by permitting the 2nd speed formation from the state in which the 2nd speed formation is prohibited and the 1st speed is formed, if the vehicle speed is 0, the 1 → 2 shift is performed. A control device for an automatic transmission, wherein control is performed based on an elapsed time from the second-speed formation permission . The control device for an automatic transmission according to claim 2 ,
It has a counter that measures the elapsed time from the second speed formation permission, and when the vehicle speed when performing the 1 → 2 shift is 0, the time measured by the counter is set in advance A control device for an automatic transmission , wherein the 1 → 2 shift is terminated when the value is reached . In the control device for an automatic transmission according to any one of claims 1 to 3,
The control device for an automatic transmission, wherein the vehicle reverse determination means determines that “the vehicle is likely to reverse” when a condition that “the gradient of the road surface is an uphill road” is satisfied . In the control device for an automatic transmission according to any one of claims 1 to 4 ,
The shift speed formation control means prohibits the formation of the second speed, and then establishes the second speed when the condition of “the brake is ON” or “the road surface has a non-climbing slope” is satisfied. control device for an automatic transmission and permits the.

Images