JP2007139155A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain reduction in the execution probability of neutral control. <P>SOLUTION: An ECU executes programs including steps of: (S100) calculating an average value cmc (1) of a brake master cylinder pressure upon vehicle complete stop; (S112) executing neutral control when the detected brake master cylinder pressure is smaller than a threshold cmc (0) (S102: NO), and is equal to or more than the average value cmc (1) (S108: YES), and neutral control execution conditions other than the condition about the brake master cylinder pressure are established (S110: YES); (S114) setting a hill-hold control instruction pressure in accordance with the average value cmc (1); and (S116) executing hill-hold control. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an automatic transmission control device, and more particularly, to an automatic transmission control device that performs neutral control.

  An automatic transmission mounted on a vehicle is configured to include a transmission mechanism that is connected to an engine via a torque converter or the like and has a plurality of power transmission paths. For example, an automatic transmission is automatically set based on an accelerator opening and a vehicle speed. The power transmission path is automatically switched, that is, the gear ratio (travel speed stage) is automatically switched. Generally, a vehicle having an automatic transmission is provided with a shift lever operated by a driver, and a shift position (for example, a reverse travel position, a neutral position, a forward travel position) is set based on the shift lever operation. The automatic shift control is performed within the thus set shift position (usually in the forward travel position).

  In a vehicle having such an automatic transmission, in a state where the forward traveling position is set and the vehicle is stopped, the driving force from the idling engine is transmitted to the transmission via the torque converter, which is the wheel. Therefore, a so-called creep phenomenon occurs. Creep phenomenon is very useful under certain conditions, such as smooth starting from a stop on an uphill road, but it is an unnecessary phenomenon when you want to keep the vehicle stopped, and it activates the vehicle brake To suppress the creep force. That is, the creep force from the engine is suppressed by the brake, and there is a problem that the fuel consumption of the engine is reduced accordingly.

  For this reason, in the forward travel position, when the brake pedal is depressed and the brake is activated, and the accelerator is almost fully closed and the vehicle is stopped, the transmission remains in the forward travel position to neutral. It has been proposed to improve fuel efficiency in a near neutral state.

  Japanese Patent Laying-Open No. 2005-42743 (Patent Document 1) discloses a vehicle start control device that determines the end of return from neutral control in accordance with the brake state of the vehicle. This start control device is a start control device for a vehicle equipped with an automatic transmission having an engagement element that is engaged when the vehicle starts. When the vehicle stops at a forward traveling position that satisfies a predetermined condition, neutral control is performed to release the engagement element. When a separately defined condition is satisfied, return control from the neutral control is executed. The start control device includes detection means for detecting the brake state of the vehicle, and determination means for determining completion of return from neutral control based on the brake state detected by the detection means.

According to the start control device disclosed in the above publication, when returning from neutral control, based on the brake state of the vehicle, for example, the stronger the braking force of the brake, the slower the return from neutral control is determined, and the brake The weaker the braking force, the faster the return from neutral control is determined. That is, when the return control from the neutral control is performed while the vehicle brake is on, the vehicle sensitivity and the torque ratio when the starting clutch is engaged differ depending on when the vehicle brake is off. For this reason, it is possible to vary the return determination from the neutral control based on the brake state of the vehicle, thereby avoiding the occurrence of a shock at the time of return. As a result, it is possible to provide a vehicle start control device that can accurately determine the return from the neutral control according to the brake state of the vehicle when returning from the neutral control.
JP 2005-42743 A

  However, for example, when the neutral control is executed on the condition of the brake master cylinder pressure, the operating force of the braking device (that is, the pedaling force of the brake pedal) has individual differences depending on the driver. There is a problem that there are individual differences depending on the driver. In particular, for a driver who tends to have a relatively low operating force of the braking device, there is a possibility that the frequency of satisfying the neutral control execution condition may be reduced if conditions for the brake master cylinder pressure are uniformly determined. is there. Therefore, the execution probability of neutral control may decrease.

  Since the start control device disclosed in the above-mentioned publication relates to the return control from the neutral control, the above-described problem cannot be solved.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an automatic transmission that suppresses a decrease in the execution probability of neutral control.

  A control device for an automatic transmission according to a first invention is a control device for an automatic transmission having a friction engagement element that is engaged when the vehicle travels forward. In the vehicle, neutral control for reducing the engagement hydraulic pressure of the friction engagement element is executed when a condition regarding the state of the vehicle when the forward travel position is selected is satisfied. The control device includes a detecting means for detecting an operating state of the braking device, and a value indicating a tendency of the operating state of the braking device when the forward traveling position is selected and the vehicle is stopped. And a setting means for setting a condition relating to the operating state of the braking device based on the calculated value if the calculated value does not satisfy the condition relating to the operating state of the braking device. .

  According to the first invention, the detecting means detects the operating state (for example, brake master cylinder pressure) of the braking device. The calculating means calculates a value (for example, an average value of the brake master cylinder pressure) indicating a tendency of the operating state of the braking device when the forward traveling position is selected and the vehicle is in a stopped state. . If the calculated value does not satisfy a condition relating to the operating state of the braking device (for example, a condition that the brake master cylinder pressure is equal to or greater than a threshold value), the operating state of the braking device is determined based on the calculated value. Set the conditions for. When the calculated value does not satisfy the condition related to the operating state of the braking device when the neutral control is executed, it can be determined that the driver's operating force of the braking device tends to be low. Therefore, the frequency with which the conditions regarding the operating state of the braking device are satisfied is low, and the execution probability of the neutral control is low. Therefore, if a condition related to the operating state of the braking device is set based on the calculated value (for example, instead of the condition that the value is equal to or greater than the threshold value, the condition that the value is equal to or greater than the calculated value is set) ), The frequency of satisfying the condition relating to the operating state of the braking device increases, and it is possible to suppress a decrease in the execution probability of the neutral control. Therefore, it is possible to provide a control device for an automatic transmission that suppresses a decrease in the execution probability of neutral control.

  In the automatic transmission control device according to the second invention, in addition to the configuration of the first invention, the condition relating to the operating state of the braking device is that a physical quantity corresponding to the operating amount of the braking device is equal to or greater than a threshold value. This is the condition. The detection means includes means for detecting a physical quantity corresponding to the operation amount of the braking device. The calculating means includes means for calculating an average value of physical quantities when the forward traveling position is selected and the vehicle is in a stopped state. The setting means sets a condition that the physical quantity corresponding to the operation amount of the braking device is equal to or greater than the average value instead of the condition that the calculated average value is smaller than the threshold value when the calculated average value is smaller than the threshold value. Means for.

  According to the second invention, the detection means detects a physical quantity (for example, brake master cylinder pressure) corresponding to the operation amount of the braking device. The calculation means calculates an average value of physical quantities when the forward travel position is selected and the vehicle is in a stopped state. The setting means sets a condition that the physical quantity corresponding to the operation amount of the braking device is equal to or greater than the average value instead of the condition that the calculated average value is smaller than the threshold value when the calculated average value is smaller than the threshold value. . When the average value is smaller than the threshold value, the probability that the physical quantity becomes equal to or higher than the threshold value is low, and thus the neutral control execution probability decreases. Therefore, by setting a condition that the physical quantity corresponding to the operation amount of the braking device is not less than the average value instead of the condition that the braking device is more than the threshold value, the driver's operating force of the braking device tends to be low. Even so, it is possible to increase the frequency at which the physical quantity satisfies the condition for executing the neutral control. Therefore, it is possible to suppress a decrease in the execution probability of the neutral control.

  In the automatic transmission control apparatus according to the third aspect of the invention, in addition to the configuration of the second aspect of the invention, the physical quantity is the brake master cylinder pressure.

  According to the third invention, when the average value of the brake master cylinder pressure is smaller than the threshold value, it can be said that the frequency at which the brake master cylinder pressure becomes equal to or higher than the threshold value by the operation of the driver is low. Therefore, the execution probability of neutral control becomes low. Therefore, when the average value is smaller than the threshold value, the condition that the brake master cylinder pressure is executed in the neutral control is set by setting the condition that the average value is equal to or higher than the threshold value. The frequency of satisfying can be increased. Therefore, it is possible to suppress a decrease in the execution probability of the neutral control.

  In the control apparatus for an automatic transmission according to the fourth invention, in addition to the configuration of any one of the first to third inventions, the automatic transmission may be configured so that the output shaft of the automatic transmission after the neutral control is executed. And a movement preventing frictional engagement element engaged to limit the rotation of the frictional engagement element. When a condition determined separately regarding the state of the vehicle is satisfied, the return control from the neutral control is executed and the movement preventing frictional engagement element is released. The control device further includes a changing means for changing the engagement hydraulic pressure of the frictional engagement element for movement prevention according to the calculated average value when the calculated average value is smaller than the threshold value.

  According to the fourth invention, when the calculated average value is smaller than the threshold value, the changing means changes the engagement hydraulic pressure of the movement preventing frictional engagement element in accordance with the calculated average value. When the calculated average value becomes smaller than the threshold value, the brake master cylinder pressure tends to be low during the neutral control execution or during the neutral control return. Therefore, when a road surface having a gradient such as an uphill road is stopped, there is a possibility that the vehicle will move (slid down) due to insufficient braking force to stop the vehicle during stopping or at the time of starting. Therefore, if the engagement hydraulic pressure in the frictional engagement element for movement prevention is changed to increase, for example, according to the calculated average value, the braking force for stopping the vehicle can be increased. Accordingly, the vehicle can be prevented from moving backward.

  In the automatic transmission control apparatus according to the fifth aspect of the invention, in addition to the configuration of the fourth aspect of the invention, the changing means changes the engagement hydraulic pressure of the frictional engagement element for movement prevention during the neutral control return transition. Including means.

  According to the fifth invention, the changing means changes the engagement hydraulic pressure of the movement preventing frictional engagement element during the neutral control return transition. At the time of transition from neutral control, control is performed such that the engagement hydraulic pressure of the frictional engagement element for power transmission increases and the engagement hydraulic pressure of the frictional engagement element for movement prevention decreases. At this time, if the average value of the brake master cylinder pressure is smaller than the threshold value, the braking force for stopping the vehicle may be insufficient. Therefore, the vehicle may move backward before the vehicle starts after returning from the neutral control. Therefore, at the neutral control return transition time, when the engagement hydraulic pressure of the movement preventing frictional engagement element is changed to increase, for example, compared with the case where the average value is larger than the threshold value, the vehicle is stopped. Power can be increased. Therefore, it is possible to prevent the vehicle from moving backward when the vehicle starts after returning.

  In the control device for an automatic transmission according to the sixth invention, in addition to the configuration of the fourth or fifth invention, the changing means may be configured to prevent the movement-preventing friction coefficient when the calculated average value is smaller than the threshold value. Means for increasing the engagement hydraulic pressure of the coupling element.

  According to the sixth invention, the changing means increases the engagement hydraulic pressure of the movement preventing frictional engagement element when the calculated average value becomes smaller than the threshold value. As a result, it is possible to prevent the vehicle from moving backward due to the tendency that the brake master cylinder pressure tends to be low during the execution of the neutral control or the return of the neutral control.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  A vehicle equipped with a control device for an automatic transmission according to an embodiment of the present invention will be described with reference to FIG. This vehicle is an FF (Front engine Front drive) vehicle. The vehicle equipped with the automatic transmission control device according to the present embodiment may be a vehicle other than FF.

  The vehicle includes an engine 102, an automatic transmission 104, drive shafts 120 and 122, front wheels 124 and 126, a brake booster 136, a master cylinder 106, a brake actuator 108, a hydraulic circuit 110, and a brake mechanism 112. And an ECU (Electronic Control Unit) 100.

  The engine 102 is an internal combustion engine that burns a mixture of fuel and air injected from an injector (not shown) in a combustion chamber of a cylinder. The piston in the cylinder is pushed down by the combustion, and the crankshaft is rotated. An external combustion engine may be used instead of the internal combustion engine. Further, a rotating electrical machine or the like may be used instead of the engine 102.

  Automatic transmission 104 includes a torque converter (not shown), a planetary gear unit 3000, and a hydraulic circuit 4000. The planetary gear unit 3000 is provided with a plurality of friction engagement elements such as a clutch and a brake that will be described in detail later. The engagement force in each element is controlled by the hydraulic circuit 4000 based on a control signal from the ECU 100. By changing the engagement force in each element, a desired gear stage is formed, and the rotation speed of the crankshaft is changed to a desired rotation speed. The output gear of the automatic transmission 104 is in mesh with the differential gear.

  Drive shafts 120 and 122 are connected to the differential gear by spline fitting or the like. Power is transmitted to the left and right front wheels 124 and 126 via the drive shafts 120 and 122.

  A brake disc 138 is provided at one end of the drive shaft 122 on the front wheel 126 side. The brake disc 138 is provided with a brake mechanism 112. The brake mechanism 112 includes a wheel cylinder, and the wheel cylinder is provided so as to sandwich the brake disc 128 via a brake pad. The brake mechanism 112 is connected to one end of the brake hydraulic circuit 110. When the hydraulic pressure in the brake hydraulic circuit 110 increases, the hydraulic pressure applied to the wheel cylinder increases. As the hydraulic pressure increases, the force with which the wheel cylinder pinches the brake disc via a brake pad (not shown) increases. When the frictional force generated between the brake pad and the brake disk increases, the rotation of the front wheel 126 is limited. Therefore, when the hydraulic pressure in the brake mechanism 112 increases, a braking force corresponding to the increased hydraulic pressure is generated in the vehicle. The brake mechanism 112 is provided on each vehicle wheel. In the present embodiment, the brake mechanism 112 has been described as a disc brake, but may be a drum brake, for example.

  Master cylinder 106 is connected to the other end of brake hydraulic circuit 110. The master cylinder 106 is provided with a piston (not shown) inside. Then, when the piston moves in response to an input from the brake booster 136, the hydraulic pressure in the master cylinder 106 increases, and accordingly, the hydraulic pressure in the brake hydraulic circuit 110 increases.

  The brake booster 136 uses the negative pressure on the intake side during operation of the engine 102 to boost the pedaling force input to the brake pedal 132 and transmits it to the master cylinder 106. Note that the structure and operation of the brake booster 136 are well-known techniques and will not be described in detail here.

  The master cylinder 106 and the brake hydraulic circuit 110 are connected via a brake actuator 108. The brake actuator 108 includes a solenoid valve and an electric pump. The brake actuator 108 receives a control signal from the ECU 100, operates the electromagnetic valve and the electric pump, and raises or lowers the hydraulic pressure in the brake hydraulic circuit 110. The brake hydraulic circuit 110 is a liquid passage (pipe) that is connected from the brake actuator 108 to the brake mechanism 112 and is filled with brake fluid.

  In the present embodiment, the brake pedal 132, the brake booster 136, the master cylinder 106, the brake actuator 108, the brake hydraulic circuit 110, and the brake mechanism 112 constitute a “braking device”.

  In the ECU 100, a vehicle speed sensor 118, a position switch 116 of the shift lever 114, a stop lamp switch 130 provided on the brake pedal 132, and a hydraulic pressure sensor 128 of the master cylinder 106 are electrically connected via a harness or the like. It is connected.

  The vehicle speed sensor 118 detects the vehicle speed from the rotational speed of the drive shaft 120 and transmits a signal representing the vehicle speed to the ECU 100. The vehicle speed sensor 118 is provided on each wheel of the vehicle.

  The position switch 116 detects the position of the shift lever 114. The position switch 116 transmits a signal indicating the position of the shift lever 114 to the ECU 100. Corresponding to the position of the shift lever 114, the gear stage of the automatic transmission 104 is automatically formed.

  The stop lamp switch 130 detects the on / off state of the brake pedal 132 and transmits a signal representing the detection result to the ECU 100. Instead of the stop lamp switch 130, a stroke sensor that detects the stroke amount of the brake pedal 132 may be provided. The hydraulic pressure sensor 128 detects the hydraulic pressure (brake master cylinder pressure) inside the master cylinder 106 and transmits a signal representing the hydraulic pressure to the ECU 100.

  The ECU 100 determines whether the vehicle is in a desired state based on signals and signals sent from the vehicle speed sensor 118, the position switch 116, the stop lamp switch 130, the hydraulic pressure sensor 128, a map and a program stored in a ROM (Read Only Memory). The equipment is controlled so that The control device for the automatic transmission according to the present embodiment is realized by ECU 100.

  The planetary gear unit 3000 will be described with reference to FIG. Planetary gear unit 3000 is connected to a torque converter 3200 having an input shaft 3100 coupled to a crankshaft. The planetary gear unit 3000 includes a first set 3300 of planetary gear mechanisms, a second set 3400 of planetary gear mechanisms, an output gear 3500, a B1 brake 3610, a B2 brake 3620, and a B3 brake 3630 fixed to the gear case 3600. , C1 clutch 3640, C2 clutch 3650, and one-way clutch F3660.

  The first set 3300 is a single pinion type planetary gear mechanism. First set 3300 includes sun gear S (UD) 3310, pinion gear 3320, ring gear R (UD) 3330, and carrier C (UD) 3340.

  Sun gear S (UD) 3310 is fixed to output shaft 3210 of torque converter 3200. Pinion gear 3320 is rotatably supported by carrier C (UD) 3340. Pinion gear 3320 is engaged with sun gear S (UD) 3310 and ring gear R (UD) 3330.

  Ring gear R (UD) 3330 is fixed to gear case 3600 by B3 brake 3630. Carrier C (UD) 3340 is fixed to gear case 3600 by B1 brake 3610.

  The second set 3400 is a Ravigneaux type planetary gear mechanism. The second set 3400 includes a sun gear S (D) 3410, a short pinion gear 3420, a carrier C (1) 3422, a long pinion gear 3430, a carrier C (2) 3432, a sun gear S (S) 3440, and a ring gear R. (1) (R (2)) 3450.

  Sun gear S (D) 3410 is coupled to carrier C (UD) 3340. Short pinion gear 3420 is rotatably supported by carrier C (1) 3422. Short pinion gear 3420 is engaged with sun gear S (D) 3410 and long pinion gear 3430. Carrier C (1) 3422 is coupled to output gear 3500.

  Long pinion gear 3430 is rotatably supported by carrier C (2) 3432. Long pinion gear 3430 is engaged with short pinion gear 3420, sun gear S (S) 3440, and ring gear R (1) (R (2)) 3450. Carrier C (2) 3432 is coupled to output gear 3500.

  Sun gear S (S) 3440 is coupled to output shaft 3210 of torque converter 3200 by C1 clutch 3640. Ring gear R (1) (R (2)) 3450 is fixed to gear case 3600 by B2 brake 3620 and connected to output shaft 3210 of torque converter 3200 by C2 clutch 3650. The ring gear R (1) (R (2)) 3450 is connected to the one-way clutch F3660, and cannot rotate when the first gear is driven.

  FIG. 3 shows an operation table showing the relationship between each gear position and the operation state of each clutch and each brake. “◯” represents engagement. “X” represents release. “◎” represents engagement only during engine braking. “Δ” represents engagement only during driving. By operating each brake and each clutch with the combination shown in this operation table, a forward gear stage of 1st to 6th speed and a reverse gear stage are formed.

  Since the one-way clutch F3660 is provided in parallel with the B2 brake 3620, as indicated by “エ ン ジ ン” in the operation table, the driving state from the engine side when the first gear (1ST) is formed (during acceleration) There is no need to engage the B2 brake 3620. In the present embodiment, one-way clutch F3660 prevents rotation of ring gear R (1) (R (2)) 3450 when the first gear is driven. When the engine brake is applied, the one-way clutch F3660 does not prevent the ring gear R (1) (R (2)) 3450 from rotating.

  In the vehicle power train as described above, the ECU 100 shifts from the neutral control non-execution mode (shift mode corresponding to the forward travel position) to the neutral control start mode when the condition regarding the vehicle state is satisfied. Specifically, the ECU 100 determines that the shift position is the forward travel position, the vehicle state is a predetermined condition (for example, accelerator off and brake on and the brake master cylinder pressure is equal to or greater than a predetermined value and the vehicle speed is If it is determined that (substantially zero or the like) is established, neutral control for controlling the C1 clutch 3640 to a predetermined slip state (half-engaged state) or released state is executed. Since the C1 clutch 3640 is released (including the slip state) by the neutral control, the load on the engine 102 due to the torque converter 3200 is reduced.

  When the ECU 100 determines that the condition of the vehicle is determined separately (for example, the brake master cylinder pressure is equal to or less than a predetermined value) when the neutral control is being executed, the neutral control return mode Then, the control is performed so that the C1 clutch 3640 is engaged so as to return from the neutral control.

  However, since the depressing force of the brake pedal 132 has individual differences depending on the driver, there is a problem that if the conditions regarding the brake master cylinder pressure are uniformly defined, the probability of performing the neutral control also has individual differences depending on the driver. In particular, for a driver who tends to have a relatively low operating force of the braking device, there is a possibility that the frequency of satisfying the condition for the brake master cylinder pressure may be reduced. Therefore, the execution probability of neutral control may decrease.

  Therefore, the present invention, when the forward traveling position is selected, and the value indicating the tendency of the operating state of the braking device when the vehicle is in a stopped state does not satisfy the neutral control execution condition, ECU 100 is characterized in that the execution condition is set based on a value indicating the tendency of the operating state of the braking device.

  Specifically, the ECU 100 calculates an average value of the brake master cylinder pressure when the forward traveling position is selected and the vehicle is in a stopped state. When the calculated average value is smaller than the threshold value corresponding to the neutral control execution condition, the ECU 100 replaces the condition with respect to the brake master cylinder pressure, which is equal to or greater than the threshold value, with a condition that the calculated average value is equal to or greater than the average value. Set.

  At this time, if the brake master cylinder pressure detected by the hydraulic pressure sensor 128 is equal to or higher than the average value, the ECU 100 determines that the condition is established for the brake master pressure. The ECU 100 executes neutral control when other neutral control execution conditions are satisfied.

  In the present embodiment, the condition relating to the operating state of the braking device is described as a condition for the brake master cylinder pressure, but the physical amount corresponding to the operating amount of the braking device is particularly limited to this. It is not something. For example, instead of the condition for the brake master cylinder pressure, the condition for the depression force of the brake pedal 132 or the condition for the stroke amount of the brake pedal 132 may be used.

  Further, in the present embodiment, the past average of the brake master cylinder pressure when the forward traveling position is selected and the vehicle is in the stopped state as the value indicating the tendency of the operating state of the braking device. The history of values is used, but is not particularly limited to this. For example, when the forward travel position is selected and the vehicle is stopped, the minimum value of the brake master cylinder pressure + in advance A predetermined value may be used.

  In addition, the ECU 100 executes neutral control and hill hold control. When the automatic transmission 104 is brought into a state close to the neutral state by the neutral control, the vehicle may retreat on a road surface having a gradient such as an uphill road. While the neutral control is being executed, the driver is stepping on the brake pedal, so there is little risk of the vehicle going backward, but the neutral state continues when the brake pedal is operated to the release side and the neutral state continues, so the vehicle moves backward. There is a case. Therefore, the ECU 100 executes the neutral control and sets the engagement hydraulic pressure of the reverse engagement friction engagement element engaged so as to limit the reverse rotation (rotation on the vehicle reverse side) of the output shaft of the automatic transmission 104. The hill hold control to raise is executed. If the engagement hydraulic pressure of the frictional engagement element for preventing the reverse is increased, the reverse rotation of the output shaft of the automatic transmission 104 is restricted, so that the reverse of the vehicle is prevented. In addition, the ECU 100 reduces the engagement hydraulic pressure of the raised frictional engagement element for preventing reverse movement when returning from the neutral control. At this time, the ECU 100 decreases the engagement hydraulic pressure of the reverse engagement frictional engagement element by a predetermined amount of change from the initial value. The initial value is not particularly limited as long as the initial value is set to be equal to or lower than the engagement hydraulic pressure of the frictional engagement element for preventing reverse movement during the neutral control. Note that the reverse rotation of the output shaft of the automatic transmission 104 is restricted by engaging a frictional engagement element for preventing reverse movement as hill hold control to prevent the vehicle from moving backward. Friction engagement elements that limit rotation (both reverse rotation and forward rotation) are provided, and such friction engagement elements may be engaged during neutral control to prevent movement of the vehicle.

  In the present embodiment, the anti-retraction frictional engagement element is the B1 brake 3610. When the B1 brake 3610 is engaged, the rotation of the sun gear S (D) 3410 is limited. At this time, when reverse rotation force is applied to the output gear 3500 so that the vehicle moves backward, the one-way clutch F3660 fixes the rotation of the ring gear R (1) (R (2)), so that the vehicle is restricted from moving backward.

  Hereinafter, with reference to FIG. 4, a control structure of a program for executing neutral control executed by ECU 100 that is the automatic transmission according to the present embodiment will be described.

  In step (hereinafter, step is referred to as S) 100, ECU 100 calculates an average value cmc (1) of the brake master cylinder pressure when the vehicle is completely stopped. Specifically, the ECU 100 is the average value cmc (1) of the brake master cylinder pressure when the forward travel position is selected and the vehicle is completely stopped (that is, the vehicle speed is substantially zero). ) Is calculated.

  For example, the ECU 100 stores a change in the brake master cylinder pressure between when the forward running position is selected and when the vehicle is completely stopped and started each time the vehicle is stopped and started. To remember.

  For example, a table in which N average values P (1) to P (N) are written is stored in the memory. The ECU 100 calculates an average value of the brake master cylinder pressure from when the vehicle is completely stopped until it starts. Then, ECU 100 rewrites the average value written first among the average values P (1) to P (N) written in the table to the calculated average value. ECU 100 separately executes a program for performing such processing. N is a natural number and is a predetermined value. For example, N is 10 when the average value cmc (1) is calculated based on the history of the past 10 times.

  Then, in step S100, the ECU 100 is based on the history of the past average values P (1) to P (N) written in the table (specifically, the sum from P (1) to P (N)). Is divided by N), and an average value cmc (1) is calculated.

  The method for calculating the average value cmc (1) is not particularly limited to the above-described method, and the total average value of the calculated past average values may be calculated. The average values P (1) to P (N) are not particularly limited as long as they are average values from when the vehicle has completely stopped until the vehicle starts, for example, after the vehicle has completely stopped. It may be an average value of a predetermined period until the vehicle starts, or after a predetermined first period has elapsed after the complete stop until a predetermined second period of start The brake master cylinder pressure may be changed at a substantially constant value not more than a predetermined value during the period from when the vehicle has completely stopped until the vehicle starts. The average value of the period may be used.

  The average value cmc (1) may be calculated every calculation cycle, or may be calculated every time the above-described table is updated and stored in a memory or the like.

  In S102, ECU 100 determines whether or not the brake master cylinder pressure detected by hydraulic pressure sensor 128 is greater than or equal to threshold value cmc (0), which is a neutral control execution condition. The threshold value cmc (0) is a predetermined initial value corresponding to the condition relating to the operating state of the braking device when the neutral control is executed. If the detected brake master cylinder pressure is equal to or greater than threshold value cmc (0) (YES in S102), the process proceeds to S104. If not (NO in S102), the process proceeds to S108.

  In S104, ECU 100 determines whether or not a neutral control execution condition other than the condition for the brake master cylinder pressure is satisfied. The neutral control execution conditions other than the conditions for the brake master cylinder pressure are, for example, the condition that the shift position is the D position, the condition that the accelerator is off, and the brake on (that is, the brake lamp switch is on). A condition that the vehicle speed is equal to or lower than a predetermined vehicle speed, and a condition that the condition is satisfied continuously for a predetermined time. The neutral control execution conditions are not limited to the above-described conditions. If a neutral control execution condition other than the brake master cylinder pressure condition is satisfied (YES in S104), the process proceeds to S106. If not (NO in S104), the process returns to S100.

  In S106, ECU 100 executes neutral control. Specifically, hydraulic circuit 4000 is controlled so that C1 clutch 3640 is in a predetermined slip state (half-engaged state) or released state.

  In S108, ECU 100 determines whether or not the brake master cylinder pressure detected by hydraulic pressure sensor 128 is equal to or greater than the calculated average value cmc (1). If the detected brake master cylinder pressure is equal to or greater than average value cmc (1) (YES in S108), the process proceeds to S110. If not (NO in S108), the process returns to S100.

  In S110, ECU 100 determines whether or not a neutral control execution condition other than the condition for the brake master cylinder pressure is satisfied. If a neutral control execution condition other than the brake master cylinder pressure condition is satisfied (YES in S110), the process proceeds to S112. If not (NO in S110), the process returns to S100.

  In S112, ECU 100 executes neutral control. In S114, ECU 100 sets a hill hold control command pressure corresponding to the calculated average value cmc (1), that is, a control command pressure for B1 brake 3610. More specifically, ECU 100 predetermines the control command pressure during execution of neutral control to be greater than normal control command pressure Pb (0) (that is, when average value cmc (1) is greater than the threshold value). The control command pressure Pb (1) is increased by the specified amount. Further, the ECU 100 reduces the initial value Pb (2) of the control command pressure by a predetermined amount when the engagement hydraulic pressure of the reverse engagement frictional engagement element when returning to the neutral control is decreased by a predetermined change amount. The increased initial value Pb (3) is set. In the present embodiment, the control command pressure for the B1 brake 3610 during the neutral control execution and during the neutral control return is set. However, the present invention is not limited to this, and the control during the neutral control execution is not limited thereto. It is only necessary to set at least one of the command pressure and the initial value of the control command pressure when returning to neutral control. In the following description, the control command pressure of the B1 brake 3610 is also referred to as a hill hold control command pressure.

  In S116, ECU 100 executes hill hold control. That is, ECU 100 increases the hill hold control command pressure.

  The operation of ECU 100 that is the control device for the automatic transmission according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG.

  As shown in FIG. 5F, it is assumed that the vehicle is traveling at a vehicle speed V (0). When the brake pedal 132 is depressed by the driver, the stop lamp switch 130 is turned on at time T (0) when the stroke amount is a predetermined amount as shown in FIG. 5 (B).

  When the brake pedal 132 is further depressed by the driver, the brake master cylinder pressure starts to increase as shown by the solid line in FIG. When the brake master cylinder pressure increases, a braking force is developed in the front wheels 124 and 126 due to an increase in the hydraulic pressure in the brake hydraulic circuit 110. Therefore, the vehicle speed decreases, and the vehicle speed becomes substantially zero at time T (2).

<When the calculated average value cmc (1) is larger than the threshold value cmc (0)>
ECU 100 calculates an average value cmc (1) based on average values P (0) to P (N) written in the table (S100). When the brake master cylinder pressure detected by hydraulic pressure sensor 128 is smaller than cmc (0) (NO in S102), the detected brake master cylinder pressure is smaller than cmc (1) (NO in S108). Since the detected brake master cylinder pressure is smaller than the threshold value, the condition is not satisfied for the brake master cylinder pressure.

  At time T (3), as shown in FIG. 5E, when the brake master cylinder pressure detected by hydraulic pressure sensor 128 becomes equal to or greater than cmc (0) (YES in S102), the brake master cylinder pressure is determined. The condition is met. Then, when other conditions are satisfied at time T (4) (YES in S104), as shown in FIG. 5A, the neutral control non-execution mode is shifted to the neutral control start mode (S106). While shifting to the neutral control start mode, as shown in FIG. 5C, the control command pressure of the C1 clutch 3640 decreases. When the engagement hydraulic pressure of the C1 clutch 3640 decreases, the C1 clutch 3640 enters a released state (including a slip state), and the automatic transmission 104 enters a state close to neutral.

  Then, at time T (5), as shown in FIG. 5D, hill hold control is executed, that is, the control command pressure of the B1 brake 3640 increases (S116). At this time, the engagement hydraulic pressure in the B1 brake 3610 increases, and the reverse rotation (rotation on the vehicle reverse side) of the output gear 3500 of the automatic transmission 104 is restricted. Thereafter, at time T (6), the neutral control start mode is shifted to the neutral control execution mode.

  As the driver operates the brake pedal 132 to the release side, the brake master cylinder pressure starts to decrease. At time T (7), when the brake master cylinder pressure becomes equal to or lower than a predetermined pressure that is a condition corresponding to the return from the neutral control, the neutral control execution mode shifts to the return mode.

  In the present embodiment, it has been described that the condition corresponding to the return is equal to or lower than a predetermined pressure. However, the present invention is not particularly limited to this, and is, for example, a neutral control execution condition. It is good also as conditions that it is smaller than a threshold value.

  While shifting to the return mode, as shown in FIG. 5C, the control command pressure of the C1 clutch 3640 increases. Furthermore, as shown by the solid line in FIG. 5D, the hill hold control command pressure starts to decrease. At this time, the hill hold control command pressure is controlled so as to decrease by a predetermined change amount from the initial value Pb (2). When the C1 clutch 3640 is engaged and the B1 brake 3610 is released, the mode is shifted from the return mode to the neutral control non-execution mode. That is, the shift mode corresponding to the forward travel position is entered. Therefore, at time T (8), the vehicle speed increases due to the driver operating the accelerator pedal, or the vehicle speed increases due to creep force. After the vehicle starts, the average value of the brake master cylinder pressure between T (2) and T (8) is calculated, and the table is updated.

<When average value cmc (1) is smaller than threshold value cmc (0)>
In this case, for convenience of explanation, the average value cmc (1) is larger than the threshold value cmc (0) as compared with the case where the average value cmc (1) is larger than the threshold value cmc (0). It is assumed that the change in the state of the vehicle other than that is small is the same.

  ECU 100 calculates an average value cmc (1) based on average values P (0) to P (N) written in the table (S100). If the brake master cylinder pressure detected by hydraulic pressure sensor 128 is smaller than cmc (0) (NO in S102) and smaller than cmc (1) (NO in S108), the condition for brake master cylinder pressure is Not satisfied.

  At time T (1), as shown in FIG. 5E, when the brake master cylinder pressure detected by the hydraulic pressure sensor 128 becomes equal to or higher than cmc (1) (NO in S102, YES in S108), The condition for the brake master cylinder pressure is established. Then, when other conditions are satisfied at time T (4) (YES in S104), as shown in FIG. 5A, the neutral control non-execution mode is shifted to the neutral control start mode (S106). While shifting to the neutral control start mode, as shown in FIG. 5C, the control command pressure of the C1 clutch 3640 decreases. Thereby, the automatic transmission 104 becomes a state close to neutral.

  Then, at time T (5), as shown in FIG. 5D, hill hold control is executed, that is, the control command pressure of the B1 brake 3610 is increased (S116). The control command pressure of the B1 brake 3610 at this time is Pb (1) that is increased by a predetermined amount from Pb (0). As a result, reverse rotation (rotation on the vehicle reverse side) of the output gear 3500 of the automatic transmission 104 is limited. Thereafter, at time T (6), the neutral control start mode is shifted to the neutral control execution mode.

  While the driver operates the brake pedal 132 to the release side, the brake master pressure starts to decrease. At time T (7), when the brake master cylinder pressure becomes equal to or lower than a predetermined pressure that is a condition corresponding to the return from the neutral control, the neutral control execution mode shifts to the return mode.

  While shifting to the return mode, as shown in FIG. 5C, the control command pressure of the C1 clutch 3640 increases. Furthermore, as shown by the solid line in FIG. 5D, the hill hold control command pressure starts to decrease. At this time, the hill hold control command pressure is determined in advance from an initial value Pb (3) increased by a predetermined amount from the initial value Pb (2) when cmc (1) is larger than cmc (0). It is controlled to decrease with the amount of change. When the C1 clutch 3640 is engaged and the B1 brake 3610 is released, the mode is shifted from the return mode to the neutral control non-execution mode. That is, the shift mode corresponding to the forward travel position is entered. Therefore, at time T (8), the vehicle speed increases due to the driver operating the accelerator pedal, or the vehicle speed increases due to creep force. After the vehicle starts, the average value of the brake master cylinder pressure between T (2) and T (8) is calculated, and the table is updated.

  As described above, when the average value cmc (1) is smaller than the threshold value cmc (0), for example, the brake master cylinder pressure is smaller than the threshold value cmc (0) as shown by the one-dot chain line in FIG. Even if the value changes, since the condition for the brake master cylinder pressure is satisfied at time T (1), a decrease in the execution probability of the neutral control is suppressed. Further, since the hill hold control command pressure increases compared to the case where the average value cmc (1) is larger than the threshold value cmc (0), the braking force against the reverse of the vehicle increases.

  As described above, according to the control device for an automatic transmission according to the present embodiment, when the calculated average value of the brake master cylinder pressure does not satisfy the condition for executing the neutral control, the driver operates the braking device. It can be judged that the power tends to be low. Therefore, if the calculated average value is smaller than the threshold value that is a condition for the brake master cylinder pressure, a condition that the calculated average value is equal to or greater than the threshold value is set instead of the condition that the calculated average value is equal to or greater than the threshold value. As a result, the frequency of satisfying the condition for the brake master cylinder pressure is increased, and a decrease in the execution probability of the neutral control can be suppressed. Therefore, it is possible to provide a control device for an automatic transmission that suppresses a decrease in the execution probability of neutral control.

  Further, when the calculated average value becomes smaller than the threshold value, the brake master cylinder pressure tends to be low during the neutral control execution or during the neutral control return. Therefore, if the engagement hydraulic pressure in the anti-reverse friction engagement element is changed in accordance with the calculated average value, the braking force for stopping the vehicle can be increased. Accordingly, the vehicle can be prevented from moving backward.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the structure of the vehicle carrying the control apparatus of the automatic transmission which concerns on this Embodiment. It is a skeleton figure which shows a planetary gear unit. It is a figure which shows the operation | movement table | surface showing the response | compatibility of each gear stage, each brake, and each clutch. It is a flowchart which shows the control structure of the program performed with ECU which is a control apparatus of the automatic transmission which concerns on this Embodiment. It is a timing chart which shows operation | movement of ECU which is a control apparatus of the automatic transmission which concerns on this Embodiment.

Explanation of symbols

  100 ECU, 102 Engine, 104 Automatic transmission, 106 Master cylinder, 108 Brake actuator, 110 Brake hydraulic circuit, 112 Brake mechanism, 114 Shift lever, 116 Position switch, 118 Wheel speed sensor, 120, 122 Drive shaft, 124, 126 Front wheel, 128 hydraulic pressure sensor, 130 stop lamp switch, 132 brake pedal, 136 brake booster, 3000 planetary gear unit, 3610 B1 brake, 3620 B2 brake, 3630 B3 brake, 3640 C1 clutch, 3650 C2 clutch, 3660 one-way clutch F 4000 Hydraulic circuit.

Claims (6)

A control device for an automatic transmission having a friction engagement element that is engaged when a vehicle is traveling forward, wherein the frictional engagement is established when a condition relating to a state of the vehicle when a forward traveling position is selected is satisfied in the vehicle. Neutral control is performed to reduce the engagement hydraulic pressure of the joint element,
The controller is
Detection means for detecting the operating state of the braking device;
A calculating means for calculating a value indicating a tendency of an operating state of the braking device when the forward traveling position is selected and the vehicle is in a stopped state;
A setting means for setting a condition relating to the operating state of the braking device based on the calculated value if the calculated value does not satisfy the condition relating to the operating state of the braking device. Control device. The condition relating to the operating state of the braking device is a condition that a physical quantity corresponding to the operating amount of the braking device is a threshold value or more,
The detection means includes means for detecting a physical quantity corresponding to the operation amount of the braking device,
The calculation means includes means for calculating an average value of the physical quantities when the forward traveling position is selected and the vehicle is in a stopped state,
When the calculated average value is smaller than the threshold value, the setting means replaces the condition that the calculated average value is equal to or greater than the threshold value, and the physical quantity corresponding to the operation amount of the braking device is equal to or greater than the average value. 2. The control device for an automatic transmission according to claim 1, further comprising means for setting a certain condition.   The control device for an automatic transmission according to claim 2, wherein the physical quantity is a brake master cylinder pressure. The automatic transmission further includes a movement-preventing friction engagement element that is engaged to limit the rotation of the output shaft of the automatic transmission after the neutral control is executed, When a separately defined condition is satisfied, a return control from the neutral control is executed, and the movement preventing frictional engagement element is released,
When the calculated average value is smaller than the threshold value, the control device includes a changing means for changing the engagement hydraulic pressure of the movement preventing frictional engagement element according to the calculated average value. Furthermore, the control apparatus of the automatic transmission in any one of Claims 1-3.   The control device for an automatic transmission according to claim 4, wherein the changing means includes means for changing an engagement hydraulic pressure of the frictional engagement element for movement prevention during the transitional transition to the neutral control.   6. The change means according to claim 4, wherein the changing means includes means for increasing an engagement hydraulic pressure of the movement preventing frictional engagement element when the calculated average value becomes smaller than the threshold value. Control device for automatic transmission.

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