JP2010281347A - Control device for automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an automatic transmission capable of quickly and stably determining whether an engagement state of a lock up clutch should be released or not. <P>SOLUTION: When fuel cut of an engine 1 is executed by a fuel cut control means 41 and a lock up clutch 35 is in the engagement state or a semi-engagement state, an engagement releasing means 54 releases the engagement state or the semi-engagement state of the lock up clutch 35 because a slip rate calculated by the slip rate calculation means 52 becomes a predetermined slip rate or higher if a vehicle speed determination means 53 determines that vehicle speed Nv becomes prescribed vehicle speed or lower. The engagement releasing means 54 releases the engagement state or the semi-engagement state of the lock up clutch 35 because rotation speed Ni of a main shaft becomes prescribed rotation speed or lower if the vehicle speed determination means 53 determines that the vehicle speed Nv is higher than the prescribed vehicle speed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for an automatic transmission having a torque converter including a lockup clutch, and more particularly, to a control device for an automatic transmission that releases the engagement state of the lockup clutch at a predetermined timing when the vehicle is decelerated. About.

  In general, when the vehicle is decelerated, the fuel economy (fuel consumption) of the vehicle is improved by performing a fuel cut that stops the supply of fuel to the engine (internal combustion engine). Here, in an automatic transmission having a torque converter equipped with a lock-up clutch, in order to suppress a decrease in engine crankshaft rotation speed (engine rotation speed) and to expand an engine rotation speed region in which fuel cut is performed When the vehicle is decelerated, the lockup clutch is in the engaged state.

  However, if the driver removes his / her foot from the accelerator pedal (accelerator pedal opening fully closed) and suddenly decelerates the vehicle by depressing the brake pedal (when sudden braking is applied), the lockup clutch is engaged. If the engine is in the fixed state, an engine stall (hereinafter referred to as “engine stall”) may occur. Therefore, conventionally, when the vehicle is suddenly decelerated, the lockup clutch is forcibly released.

  As a means for forcibly releasing the engagement state of the lockup clutch, for example, a deceleration (differential value of vehicle speed of vehicle: dV / dt) is calculated based on the current vehicle speed, and from this deceleration, A value corresponding to a rate of change in deceleration (a differential value of deceleration) is calculated, and when the value falls below a predetermined value, a method of releasing the lockup clutch (see, for example, Patent Document 1) or a brake There is known a method of releasing a lock-up clutch when the hydraulic pressure of the engine rises to an engagement release region of the lock-up mechanism (see, for example, Patent Document 2).

  Further, for example, a method for determining whether or not to release the lockup clutch using only the engine speed is also known. In this case, the map data for releasing the lockup clutch with respect to the engine speed is changed. Conventionally, the vehicle air conditioner is turned ON / OFF only by changing the map data for the current gear. The map data is not changed for the failure state of the anti-lock brake system (hereinafter referred to as “ABS”).

Japanese Patent No. 2565441 Japanese Patent No. 3258444

  By the way, when the driver suddenly decelerates the vehicle while traveling in a place where the road surface is in a low μ state due to snow accumulation or freezing, especially in a vehicle not equipped with ABS or a vehicle with a broken ABS, The wheel speed of each wheel becomes 0 in a very short time. In such a case, according to the method disclosed in Patent Document 1, depending on the calculation period of the deceleration change rate, the vehicle stall may occur before the deceleration reaches a predetermined value and the lockup clutch is released. There is a problem.

  In the method disclosed in Patent Document 2, a signal from an external device (for example, a brake sensor or a FI-ECU (Fuel Injection-Electronic Control Unit)) of an automatic transmission is used as an AT-ECU (Automatic Transmission-Electronic). Control Unit) will determine whether to release the lock-up clutch after receiving, so if there is a communication delay etc., there is a possibility that the engine stalls before the lock-up clutch is released There is.

  Further, even in the method using only the engine speed, since the AT-ECU usually acquires engine speed data through communication from the FI-ECU, there is a time lag until the lockup clutch is released due to a communication delay or the like. As a result, there is a problem that the engine toughness at the time of sudden braking is lowered.

  In particular, in the method using only the engine speed, in order to improve fuel economy, the threshold value of the engine speed for determining the release of the lockup clutch is set to the lowest engine speed at which the fuel cut can be continued. ing. Therefore, in a situation where ABS failure occurs and the wheel is likely to lock during sudden braking, the fuel consumption of the self-diagnosis system (OBD) prevents the engine stall even if the lockup clutch is released at the minimum engine speed. There is also a problem that it is difficult to further improve the fuel economy because the engine speed at which the fuel cut is terminated within a range that does not fall below the standard must be set to the high speed side.

  The present invention has been made in view of the above-mentioned points, and an object of the present invention is to quickly determine whether or not the engagement state of the lockup clutch should be released using a direct parameter for the lockup control of the torque converter. An object of the present invention is to provide a control device for an automatic transmission that can make a stable determination and thereby improve the vehicle's engine toughness against sudden deceleration.

  In order to solve the above problems, the control device (4, 5) of the automatic transmission (2) according to the present invention includes an output shaft (11) of the engine (1) and an input shaft (21) of the automatic transmission (2). In the control device (4, 5) of the automatic transmission (2) having a torque converter (3) having a lockup clutch (35) that can be coupled to the lockup clutch (35), the lockup clutch (35) ) For controlling the lockup clutch control means (51), the output shaft speed detecting means (101) for detecting the rotational speed (Ne) of the output shaft (11) of the engine (1), the automatic transmission ( 2) The input shaft rotational speed detecting means (102) for detecting the rotational speed (Ni) of the input shaft (21), the rotational speed (Ne) of the output shaft (11) of the engine (1) and the automatic transmission. Based on the rotational speed (Ni) of the input shaft (21) in (2) The slip ratio calculating means (52) for calculating the slip ratio (ETR) of the torque converter (3), the vehicle speed detecting means (104) for detecting the traveling speed (Nv) of the vehicle, and the vehicle speed (Nv) are predetermined. A vehicle speed determining means (53) for determining whether or not the vehicle speed is equal to or lower than the vehicle speed, and a fuel for controlling the engine (1) so as to execute a fuel cut for cutting off fuel supply to the engine (1) during deceleration of the vehicle When the fuel cut is executed by the cut control means (41) and the fuel cut control means (41) and the lockup clutch (35) is in one of the engaged state and the semi-engaged state, The determination result by the vehicle speed determination means (53), the slip ratio (ETR) of the torque converter (3) calculated by the slip ratio calculation means (52), and the input shaft speed Based on either the rotational speed (Ni) of the input shaft (21) of the automatic transmission (2) detected by the number detecting means (102), the lock-up clutch (35) is engaged or semi-engaged. It is characterized by comprising engagement release means (54) for releasing.

  By configuring in this way, lock-up control such as torque converter slip rate and automatic transmission input shaft speed is used instead of using indirect parameters such as deceleration and brake hydraulic pressure as in the past. It is possible to determine whether or not to release the lock-up clutch engagement state using a direct parameter, so that whether or not the lock-up clutch engagement state should be released can be quickly and stably determined. Can be detected. As a result, the vehicle's engine toughness against sudden deceleration can be improved.

  In the control device for an automatic transmission according to the present invention, the disengagement means (54) determines the slip ratio calculation means when the vehicle speed determination means (53) determines that the vehicle speed (Nv) is equal to or lower than a predetermined vehicle speed. Based on the fact that the slip ratio (ETR) calculated in (52) is equal to or less than the predetermined slip ratio, the lockup clutch (35) is released from the engaged state or the semi-engaged state, and the vehicle speed determining means (53 ) Based on the fact that the rotational speed (Ni) of the input shaft (21) of the automatic transmission (2) has become equal to or lower than the predetermined rotational speed. Thus, the engagement state or the semi-engagement state of the lockup clutch (35) may be released. As a result, the parameter for releasing the engagement state of the lockup clutch is switched depending on whether the vehicle speed is equal to or lower than the predetermined vehicle speed, so that the engine can be locked more accurately without causing an engine stall when the vehicle decelerates. The engagement state of the up clutch can be released.

  In the control device for an automatic transmission according to the present invention, at least one of a shift stage of the automatic transmission (2), an ON / OFF state of an air conditioner mounted on the vehicle, and a failure state of an antilock brake system (ABS). Based on the above, the set values of the predetermined vehicle speed, the predetermined rotation speed, and the predetermined slip ratio may be changed. As a result, the fuel cut can be continuously executed up to the input shaft speed of the automatic transmission where the engine stall does not occur with respect to the responsiveness of the lockup clutch OFF, thereby further improving the fuel economy of the vehicle. Can do.

  The reference numerals in the parentheses described above exemplify corresponding constituent elements in the embodiments described later for reference.

  According to the present invention, it is possible to quickly and stably determine whether or not the engagement state of the lockup clutch should be released by using a direct parameter for the lockup control of the torque converter. It is possible to provide a control device for an automatic transmission that can improve the vehicle's engine toughness against deceleration.

It is the schematic of the drive system of the vehicle in one Embodiment of this invention. It is a block diagram which shows the control system of the control apparatus of the automatic transmission of this embodiment. It is a block diagram which shows a part of hydraulic control apparatus of the torque converter of this embodiment. It is a timing chart which shows the operation | movement of cancellation | release of the lockup clutch of this embodiment. It is a graph which shows an example of each parameter of lockup clutch release judgment processing at the time of deceleration of this embodiment. It is a flowchart which shows the lockup determination process at the time of deceleration performed in this embodiment. It is a flowchart which shows the lockup clutch release determination process at the time of deceleration performed in this embodiment.

  Hereinafter, preferred embodiments of a control device for an automatic transmission according to the present invention will be described in detail with reference to the accompanying drawings. The control device for an automatic transmission according to the present invention is realized by an electronic control unit (ECU) that controls at least the entire automatic transmission. In the present embodiment, as will be described later, the automatic transmission control device of the present invention includes an FI-ECU that controls the engine and an AT-ECU that controls the automatic transmission. However, the control device for the automatic transmission may be configured by an electronic control unit (ECU) provided integrally.

  First, a configuration of a vehicle to which a control device for an automatic transmission according to the present invention is applied will be schematically described. FIG. 1 is a schematic diagram of a vehicle drive system according to an embodiment of the present invention. As shown in FIG. 1, the vehicle according to the present embodiment includes an engine 1, an automatic transmission 2 connected to the engine 1 via a torque converter 3, a FI-ECU 4 that controls the engine 1, and a torque converter 3. And an AT-ECU 5 for controlling the automatic transmission 2 including the automatic transmission 2.

  The rotational output of the engine 1 is output to a crankshaft (output shaft of the engine 1) 11. The rotation of the crankshaft 11 is transmitted to the main shaft 21 of the automatic transmission 2 via the torque converter 3.

  Here, the configuration of the torque converter 3 will be briefly described with reference to FIG. The torque converter 3 transmits torque via a fluid (hydraulic oil). As shown in FIG. 3, the torque converter 3 includes a front cover 31, a pump impeller (pump impeller) 32 formed integrally with the front cover 31, and a pump between the front cover 31 and the pump impeller 32. A turbine impeller (turbine runner) 33 disposed opposite to the impeller 32, is interposed between the pump impeller 32 and the turbine impeller 33, and is supported on a fixed shaft 37 via a one-way clutch 36. And a stator 34. As shown in FIG. 1, the crankshaft 11 is connected to the pump impeller 32 of the torque converter 3 via the front cover 31, and the turbine impeller 33 is connected to the main shaft (input shaft of the automatic transmission 2) 21. Is done.

  A lockup clutch 35 is provided between the turbine impeller 33 and the front cover 31. The lock-up clutch 35 is engaged with the front cover 31 by being pressed toward the inner surface of the front cover 31 under the control of the hydraulic control device 6 (see FIG. 3) based on the command of the AT-ECU 5, and the pressure is released. As a result, lock-up control for releasing the engagement with the front cover 31 is performed. Hydraulic oil (ATF: Automatic Transmission Fluid) is sealed in a container formed by the front cover 31 and the pump impeller 32.

  When the lockup control is not performed, relative rotation between the pump impeller 32 and the turbine impeller 33 is allowed. In this state, when the rotational torque of the crankshaft 11 is transmitted to the pump impeller 32 via the front cover 31, the hydraulic oil that fills the container of the torque converter 3 is pumped by the rotation of the pump impeller 32. Circulation from the car 32 to the turbine impeller 33 and then to the stator 34. Thereby, the rotational torque of the pump impeller 32 is transmitted to the turbine impeller 33 to drive the main shaft 21.

  On the other hand, during the lock-up control, the lock-up clutch 35 is engaged, and the front cover 31 and the turbine impeller are not rotated from the front cover 31 to the turbine impeller 33 via hydraulic oil. 33 rotates together with the rotation torque of the crankshaft 11 and is directly transmitted to the main shaft 21.

  Returning to FIG. 1, the rotational torque of the main shaft 21 is transmitted to the counter shaft 22 via a clutch and a gear (not shown). Further, the rotational torque of the countershaft 22 is transmitted to the drive wheels through a gear and a differential mechanism (not shown).

  In the vicinity of the crankshaft 11, a crankshaft rotation speed sensor 101 that detects the rotation speed Ne of the crankshaft 11 (engine 1) is provided. In the vicinity of the main shaft 21, a main shaft rotational speed sensor 102 that detects the rotational speed Ni of the main shaft 21 is provided. In the vicinity of the countershaft 22, a countershaft rotation speed sensor 103 that detects the rotation speed No of the countershaft 22 is provided. The rotation speed data detected by each of the rotation speed sensors 101 to 103 is output to the AT-ECU 5. Further, the rotational speed data detected by the crankshaft rotational speed sensor 101 is also output to the FI-ECU 4.

  A vehicle speed sensor 104 that detects the vehicle speed Nv of the vehicle is provided at a predetermined position of the vehicle. The vehicle speed Nv may be calculated from the rotational speed Ni of the main shaft 21 or the rotational speed No of the countershaft 22 without providing the vehicle speed sensor 104 that exclusively detects the vehicle speed Nv. For example, the vehicle speed Nv can be detected (calculated) based on a relational expression such as “Nv = Ni × speed ratio × tire circumference” or “Nv = No × tire circumference”.

  Next, a control system of the automatic transmission control device of the present invention will be described. FIG. 2 is a block diagram showing a control system of the automatic transmission control device of the present embodiment. The control device for an automatic transmission according to the present invention is constituted by an FI-ECU 4 and an AT-ECU 5.

  As shown in FIG. 2, the FI-ECU 4 controls the engine 1 so as to execute the fuel cut that cuts off the fuel supply to the engine 1 based on the establishment of a predetermined condition while the vehicle is decelerating. Means 41 are provided. The predetermined condition includes that the accelerator pedal opening degree APAT is fully closed by the accelerator pedal opening degree sensor 105.

  Further, as shown in FIG. 2, the AT-ECU 5 includes a lockup clutch control unit 51, a slip ratio calculation unit 52, a vehicle speed determination unit 53, and an engagement release unit 54.

  The lockup clutch control means 51 controls the lockup clutch 35 provided in the torque converter 3 according to the driving state of the vehicle. In the lockup clutch control means 51, for example, the vehicle speed Nv detected by the vehicle speed sensor 104 is equal to or higher than a predetermined vehicle speed, and the rotational speed Ne of the engine 1 (crankshaft 11) detected by the crankshaft rotational speed sensor 101 is predetermined. When the rotational speed is equal to or higher than the rotation speed, the lockup clutch 35 is controlled to be engaged.

  In the present embodiment, the lockup clutch control means 51 performs control so that the lockup clutch 35 is engaged even when the vehicle is decelerating under a predetermined condition. Specifically, when the vehicle speed Nv is equal to or higher than a predetermined vehicle speed and the rotational speed Ne of the engine 1 is equal to or higher than the predetermined rotational speed, the lockup clutch control means 51 determines the accelerator pedal opening APAT by the accelerator pedal opening sensor 105. Even when it is fully closed and the fuel cut control means 41 performs the fuel cut control, the lockup clutch 35 is engaged.

  The slip ratio calculating means 52 is based on the rotational speed Ne of the crankshaft (the output shaft of the engine 1) 11 and the rotational speed Ni of the main shaft (the input shaft of the automatic transmission 2) 21, and the slip ratio ETR of the torque converter 3. Is calculated. The slip ratio ETR of the torque converter 3 is represented by (the rotational speed Ni of the main shaft 21) / (the rotational speed Ne of the crankshaft 11) × 100 (%). The slip ratio calculation means 52 outputs the calculated slip ratio ETR of the torque converter 2 to the engagement release means 54.

  The vehicle speed determination means 53 determines whether or not the vehicle speed Nv calculated by using the rotation speed No of the countershaft 22 detected by the vehicle speed sensor 104 or detected by the countershaft rotation speed sensor 103 is equal to or lower than a predetermined vehicle speed. Judgment. The vehicle speed determination unit 53 outputs this determination result to the disengagement unit 54.

  The disengagement unit 54 performs fuel cut on the engine 1 by the fuel cut control unit 41, and the lockup clutch 35 is in either the engaged state or the half-engaged state. Based on the determination result by the vehicle speed determination means 53, the engagement state or the semi-engagement state of the lockup clutch 35 is released.

  Specifically, the engagement release means 54 is calculated by the slip ratio calculation means 52 when the vehicle speed determination means 53 determines that the vehicle speed Nv is equal to or lower than a predetermined vehicle speed in the above situation. Based on the fact that the slip ratio ETR is equal to or lower than the predetermined slip ratio, the engagement state or the semi-engagement state of the lockup clutch 35 is released. Further, in the above situation, when the vehicle speed determination unit 53 determines that the vehicle speed Nv is higher than the predetermined vehicle speed, the engagement release unit 54 determines that the rotation speed Ni of the main shaft 21 is the predetermined rotation speed. Based on the following, the engagement state or the semi-engagement state of the lockup clutch 35 is released.

  In this way, the disengagement means 54 performs the fuel cut on the engine 1 by the fuel cut control means 41, and the lockup clutch 35 is in any one of the engaged state and the semi-engaged state. (1) When the rotational speed Ni of the main shaft 21 that is the input shaft of the automatic transmission 2 is equal to or lower than a predetermined rotational speed, or (2) the slip ratio ETR of the torque converter 3 is a predetermined slip The engagement state of the lockup clutch 35 is released when the ratio becomes lower than the ratio. In the present invention, which of the conditions (1) and (2) is applied is switched (changed) according to the determination result of the vehicle speed determination means 53 as described above.

  For example, when the vehicle is traveling in the high vehicle speed region (the high rotation region of the main shaft 21), the lockup clutch 35 is engaged when the wheel speed detected by a wheel speed sensor (not shown) suddenly decreases. If it is, the slip ratio ETR of the torque converter 3 tends to be less than 100% by being dragged by the wheel via the differential mechanism. Therefore, in this embodiment, the engagement release means 54 determines whether or not to release the engagement state of the lockup clutch 35 based on the condition (2) in this region.

  On the other hand, when the vehicle is traveling in a low vehicle speed region (low rotation region of the main shaft 21), the rotational speed Ne of the crankshaft 11 is equal to or lower than a predetermined rotational speed before the slip ratio ETR of the torque converter 3 becomes less than 100%. End up. Therefore, in this embodiment, the engagement release means 54 determines whether or not to release the engagement state of the lockup clutch 35 based on the condition (1) in this region.

  As shown in each table of FIG. 5, it is based on at least one of the shift stage (gear stage) of the automatic transmission 2, the ON / OFF state of the air conditioner mounted on the vehicle, and the failure state of the antilock brake system. Thus, the predetermined vehicle speed, the predetermined rotation speed, and the predetermined slip ratio set values used as conditions for releasing the engagement state of the lockup clutch 35 may be changed. Thereby, at the gear stage, the difference in the vehicle speed Nv and the rotational speed Ni of the main shaft 21 due to the difference in the ratio can be appropriately reflected. Further, in the slip ratio ETR, it is possible to consider the difference in input torque from the wheels depending on the vehicle speed Nv and the rotational speed Ni of the main shaft 21. Further, since the load on the engine 1 becomes large when the air conditioner is used, each threshold may be set to a high value. When the ABS fails, the wheels are likely to be locked due to sudden deceleration. Therefore, each threshold value may be set to a high value. .

  Next, with reference to FIG. 3, the structure of the hydraulic control apparatus that controls the hydraulic oil of the automatic transmission 2 and the torque converter 3 will be described. FIG. 3 is a block diagram showing a part of the hydraulic control device 6 of the torque converter 3 of the present embodiment.

  As shown in FIG. 3, the hydraulic control device 6 includes a hydraulic pump 60 for supplying hydraulic oil to the entire hydraulic control device 6. The hydraulic pump 60 is driven by the engine 1, pumps up hydraulic oil stored in an oil tank (not shown), and pumps the hydraulic oil to the main regulator valve 61 via the oil passage 71.

  The main regulator valve 61 adjusts the hydraulic oil pumped from the hydraulic pump 60 to generate the line pressure PL. The hydraulic oil of the line pressure PL adjusted by the main regulator valve 61 is supplied to a torque converter (TC) regulator valve 62, and a linear solenoid valve for the automatic transmission 2 and a linear solenoid for the lockup clutch 35 (not shown). It is supplied to the valve 65.

  Further, the hydraulic oil having the line pressure PL adjusted by the main regulator valve 61 is supplied to a CR valve (not shown). The CR valve reduces the line pressure PL of the hydraulic oil to generate a CR pressure (control pressure), and supplies the hydraulic oil with the CR pressure to each linear solenoid valve (electromagnetic valve) 65 or the like.

  The TC regulator valve 62 controls the supply of hydraulic oil to the torque converter 3, and locks up (LC) the hydraulic oil of the line pressure PL supplied from the main regulator valve 61 via an oil passage 73. Supply to valve 63. Further, the TC regulator valve 62 supplies hydraulic oil having a line pressure PL to the inside of the torque converter 3 from the back side through the oil passage 74.

  The LC control valve 63 supplies the hydraulic oil having the line pressure PL supplied via the oil passage 72 to the LC shift valve 64 via the oil passage 75. The hydraulic oil having the line pressure PL supplied in this way is used for lock-up control of the torque converter 3 via the LC shift valve 64.

  The LC shift valve 64 controls the engagement (on) / release (off) of the lockup clutch 35 by an unillustrated (electromagnetic) on / off solenoid. When the LC shift valve 64 is opened by turning on the on / off solenoid, hydraulic fluid is supplied from the front side of the lockup clutch 35 via the LC shift valve 64 and the oil passage 76, and this hydraulic fluid is locked up. The oil is discharged from the back side of the clutch 35 to the oil tank. Thereby, the lockup clutch 35 is engaged (fastened).

  On the other hand, when the on / off solenoid is turned off, the LC shift valve 64 is closed, and when the hydraulic oil is discharged from the front side to the oil tank, the lockup clutch 35 is released (not fastened). The slip amount of the lock-up clutch 35 (slip ratio ETR of the torque converter 3), that is, the engagement capacity when the torque converter 3 is slipped between engagement (at the time of lock-up) and release is the front side and the back side. Is determined by the pressure (hydraulic pressure) of the hydraulic oil supplied to the engine.

  The LC linear solenoid valve 65 generates an output pressure determined in accordance with excitation control of a solenoid (not shown), and acts on the LC control valve 63. As a result, the hydraulic oil having the line pressure PL supplied from the main regulator valve 61 is adjusted to a pressure necessary for lockup control in the LC control valve 63. Thereby, the engagement capacity (slip amount) of the lock-up clutch 35 is adjusted (controlled) by exciting / de-energizing the solenoid of the linear solenoid valve 65.

  When releasing the engagement state of the lockup clutch 35 (that is, when turning off the lockup control), the command value of the linear solenoid valve 65 is set to 0, the LC control valve 63 is closed, and the LC shift is performed. The on / off solenoid for switching between opening and closing of the valve is turned off.

  Next, the operation for releasing the engagement state of the lock-up clutch 35 will be described using the timing chart of FIG. FIG. 4 is a timing chart showing an operation of releasing the lockup clutch according to the present embodiment. FIG. 4 conceptually shows each flag and each number of revolutions when the vehicle is decelerated suddenly during an ABS failure.

  When the accelerator pedal opening APAT is fully closed at the timing of T1, the fuel cut is performed on the engine 1 by the fuel cut control means 41, and the FC execution flag is turned ON. Accordingly, in the hydraulic control device 6, the lockup control hydraulic pressure is set from P1 to P2 (<P1) by the LC control valve 63.

  Thereafter, when the driver depresses the brake pedal at the timing of T2, the brake flag F_BKSW is turned on, and the rotational speed Ne of the crankshaft 11 and the rotational speed Ni of the main shaft 21 are gradually reduced.

  Here, after the timing of T3, the difference between the rotational speed Ne of the crankshaft 11 and the rotational speed Ni of the main shaft 21 gradually increases, and the slip ratio ETR of the torque converter 3 decreases from 100%.

  In this example, since the vehicle is gradually decelerating, whether or not to release the engagement state of the lockup clutch 35 is determined based on the condition (1) when the vehicle speed Nv is equal to or lower than the predetermined vehicle speed. Determined. Under the above condition (1), when the rotational speed Ni of the main shaft 21 is equal to or lower than the predetermined rotational speed, that is, at the timing of T4, the lockup release determination flag (LCOFF determination flag) is turned ON. The LC control oil pressure is set from P2 to P3 (= 0). Thereby, the engagement state of the lockup clutch 35 is released, and the vehicle does not generate an engine stall.

  Next, the operation of the control device (AT-ECU 5) for the automatic transmission 2 according to the present embodiment will be described based on the flowcharts of FIGS. FIG. 6 is a flowchart showing a deceleration lockup (deceleration LC) determination process executed in the present embodiment. FIG. 7 is a flowchart showing a deceleration lock-up clutch release (deceleration LCOFF) determination process executed in the present embodiment.

  First, the deceleration LC determination process will be described. The AT-ECU 5 acquires the data of the accelerator pedal opening APAT detected by the accelerator pedal opening sensor 105 via the FI-ECU 4, and determines whether or not the accelerator pedal opening APAT is fully closed ( Step S101). If it is determined that the accelerator pedal opening APAT is not fully closed, the AT-ECU 5 does not perform lockup control during deceleration (step S107), and ends this deceleration LC determination process as it is.

  If it is determined that the accelerator pedal opening APAT is fully closed, whether the AT-ECU 5 is currently performing a fuel cut based on a signal from the fuel cut control means 41 of the FI-ECU 4 It is determined whether or not (step S102). If it is determined that the fuel cut is not performed, the AT-ECU 5 does not perform the lock-up control at the time of deceleration (step S107), and ends the deceleration LC determination process as it is.

  If it is determined that the fuel cut is in progress, the AT-ECU 5 subsequently determines whether or not the vehicle speed Nv of the vehicle is equal to or higher than a predetermined vehicle speed (first vehicle speed) (step S103). If it is determined that the vehicle speed Nv is slower (smaller) than the first vehicle speed, the AT-ECU 5 does not perform lockup control during deceleration (step S107), and ends the deceleration LC determination process as it is.

  When determining that the vehicle speed Nv is equal to or higher than the first vehicle speed, the AT-ECU 5 subsequently determines whether or not the rotational speed Ne of the engine 1 (crankshaft 11) is equal to or higher than a predetermined engine speed. (Step S104). When it is determined that the rotational speed Ne of the engine 1 is lower (smaller) than the predetermined engine rotational speed, the AT-ECU 5 does not perform lockup control during deceleration (step S107), and performs this deceleration LC determination process as it is. Exit.

  If it is determined that the rotational speed Ne of the engine 1 is equal to or higher than the predetermined engine rotational speed, the AT-ECU 5 performs lockup control during deceleration (step S105), and executes a deceleration LCOFF determination process described later. (Step S106), the deceleration LC determination process is terminated.

  In the deceleration LCOFF determination process, the AT-ECU 5 first determines which gear stage is set in the automatic transmission 2 under the control of the AT-ECU 5, which is the ON / OFF state of the air conditioner, and the ABS is in a failed state. Get information about whether or not. Then, the AT-ECU 5 determines the vehicle speed and the main shaft rotational speed from each table shown in FIG. 5 in order to determine whether or not to release the engagement state of the lockup clutch 35 at the subsequent stage based on these pieces of information. And the threshold values of the slip ratio of the torque converter 3 are searched (step S201).

  Next, the AT-ECU 5 determines whether or not the vehicle speed Nv is equal to or less than a threshold value (second vehicle speed <first vehicle speed) (step S202). When it is determined that the vehicle speed Nv is equal to or lower than the second vehicle speed, the AT-ECU 5 subsequently determines whether or not the rotational speed Ni of the main shaft 21 is equal to or lower than a threshold value (step S203). When the rotational speed Ni of the main shaft 21 is larger than the threshold value, it is not necessary to release the engagement state of the lockup clutch 35 yet, so this deceleration LCOFF determination process is finished as it is.

  On the other hand, if it is determined that the rotational speed Ni of the main shaft 21 is equal to or less than the threshold value, the AT-ECU 5 outputs a disengagement command for the lockup clutch 35 to the hydraulic control device 6 of the automatic transmission 2 (step). S204), the deceleration LCOFF determination process is terminated.

  If it is determined in step S202 that the vehicle speed Nv is faster (larger) than the second vehicle speed, the AT-ECU 5 subsequently determines whether or not the slip ratio of the torque converter 3 is equal to or less than a threshold (step). S205). If it is determined that the slip ratio is larger than the threshold value, it is not necessary to release the engagement state of the lockup clutch 35 yet, so the deceleration LCOFF determination process is terminated as it is. On the other hand, if it is determined that the slip ratio is equal to or less than the threshold value, the AT-ECU 5 outputs an engagement disengagement command for the lockup clutch 35 to the hydraulic control device 6 of the automatic transmission 2 (step S204). The LCOFF determination process is terminated.

  The hydraulic control device 6 that has received the engagement release command of the lockup clutch 35 sets the command value of the linear solenoid valve 65 to 0 and closes the LC control valve 63 as described above. The on / off solenoid for switching between opening and closing is turned off to close the LC shift valve 64, whereby the engagement state of the lockup clutch 35 is released.

  As described above, the control device for an automatic transmission according to the present invention includes the lockup clutch 35 that can connect the crankshaft (output shaft) 11 of the engine 1 and the main shaft (input shaft) 21 of the automatic transmission 2. In the control device (AT-ECU 5 and FI-ECU 4) of the automatic transmission 2 having the torque converter 3 having the lock-up clutch control means 51 for controlling the lock-up clutch 35 according to the driving state of the vehicle, A crankshaft rotation speed sensor 101 for detecting the rotation speed Ne of the crankshaft 11, a main shaft rotation speed sensor 102 for detecting the rotation speed Ni of the main shaft 21 of the automatic transmission 2, and the rotation speed of the crankshaft 11 of the engine 1 Based on Ne and the rotational speed Ni of the main shaft 21 of the automatic transmission 2, Slip rate calculating means 52 for calculating the slip rate ETR of the barter 3, a vehicle speed sensor 104 for detecting the vehicle speed (traveling speed) Nv of the vehicle, and whether or not the vehicle speed Nv is equal to or lower than a predetermined vehicle speed (second vehicle speed). Vehicle speed determination means 53, fuel cut control means 41 for controlling the engine 1 so as to execute fuel cut (FC) for cutting off fuel supply to the engine 1 during deceleration of the vehicle, and fuel cut control means 41 Thus, when the fuel cut is executed and the lock-up clutch 35 is in one of the engaged state and the half-engaged state, the determination result by the vehicle speed determining means 53 and the slip ratio calculating means 52 are calculated. The slip ratio ETR and the rotational speed Ni of the main shaft 21 detected by the main shaft rotational speed sensor 102 Based on Rekato, it was decided and a disengaging means 54 for releasing the engaged state or half-engaged state of the lock-up clutch 35. Since the control device for the automatic transmission 2 according to the present invention is configured as described above, the slip ratio ETR of the torque converter 3 and the main shaft 21 are not the indirect parameters such as the deceleration and the brake hydraulic pressure as in the prior art. It is possible to quickly and stably determine whether or not the engagement state of the lockup clutch 35 should be released using direct parameters for the lockup control of the torque converter 3 such as the rotational speed Ni. The vehicle toughness against sudden deceleration can be improved. In the automatic transmission control apparatus according to the present embodiment, the parameter for releasing the engagement state of the lockup clutch 35 is switched depending on whether or not the vehicle speed Nv is equal to or lower than a predetermined vehicle speed (second vehicle speed). Therefore, the engagement state of the lockup clutch 35 can be released more accurately.

  In the control device for an automatic transmission according to the present invention, the engagement release unit 54 determines the slip ratio calculation unit 52 when the vehicle speed determination unit 53 determines that the vehicle speed Nv is equal to or lower than a predetermined vehicle speed (second vehicle speed). Based on the fact that the slip ratio ETR calculated by the above becomes equal to or less than the predetermined slip ratio, the engagement state or the semi-engagement state of the lock-up clutch 35 is released, and the vehicle speed determination means 53 causes the vehicle speed Nv to be greater than the predetermined vehicle speed. When it is determined that the speed is high, the lockup clutch 35 is released from the engaged state or the semi-engaged state based on the fact that the rotational speed Ni of the main shaft 21 of the automatic transmission 2 is equal to or lower than a predetermined rotational speed. do it. Accordingly, since the parameter for releasing the engagement state of the lockup clutch 35 is switched depending on whether or not the vehicle speed Nv is equal to or lower than a predetermined vehicle speed (second vehicle speed), the vehicle is more accurately locked when the vehicle is decelerated. The engaged state of the up clutch 35 can be released.

  In the control device for an automatic transmission according to the present invention, a predetermined vehicle speed is determined based on at least one of a shift stage of the automatic transmission, an ON / OFF state of an air conditioner mounted on the vehicle, and a failure state of the antilock brake system, The predetermined rotational speed and the set value of the predetermined slip ratio may be changed. As a result, the fuel cut can be continued until the rotational speed Ni of the main shaft 21 of the automatic transmission 2 at which the engine stall does not occur with respect to the responsiveness of releasing the engaged state of the lockup clutch 35. The fuel economy can be further improved.

  As mentioned above, although embodiment of the control apparatus of the automatic transmission of this invention was described in detail based on the accompanying drawing, this invention is not limited to these structures, Claim, specification, and drawing Various modifications are possible within the scope of the technical idea described in the above. In addition, even if it has a shape, structure, or function that is not directly described in the specification and drawings, it is within the scope of the technical idea of the present invention as long as it has the effects and advantages of the present invention. That is, each part such as the AT-ECU 5, the automatic transmission 2, and the hydraulic control device 6 constituting the control device for the automatic transmission can be replaced with any configuration that can exhibit the same function. Moreover, arbitrary components may be added.

1 Engine 11 Crankshaft 2 Automatic transmission 21 Main shaft 22 Countershaft 3 Torque converter 35 Lock-up clutch 4 FI-ECU
41 Fuel cut control means 5 AT-ECU
51 Lock-up clutch control means 52 Slip rate calculation means 53 Vehicle speed determination means 54 Disengagement means 6 Hydraulic control device 61 Main regulator valve 62 TC regulator valve 63 LC control valve 101 Crankshaft speed sensor 102 Main shaft speed sensor 103 Counter Shaft speed sensor 104 Vehicle speed sensor 105 Accelerator pedal opening sensor

Claims (3)

In an automatic transmission control device including a torque converter having a lock-up clutch capable of connecting an output shaft of an engine and an input shaft of an automatic transmission,
Lock-up clutch control means for controlling the lock-up clutch according to the driving state of the vehicle;
Output shaft rotational speed detection means for detecting the rotational speed of the output shaft of the engine;
Input shaft rotational speed detection means for detecting the rotational speed of the input shaft of the automatic transmission;
Slip ratio calculating means for calculating a slip ratio of the torque converter based on the rotation speed of the output shaft of the engine and the rotation speed of the input shaft of the automatic transmission;
Vehicle speed detection means for detecting the traveling speed of the vehicle;
Vehicle speed determination means for determining whether or not the vehicle speed is equal to or lower than a predetermined vehicle speed;
Fuel cut control means for controlling the engine to perform fuel cut to cut off fuel supply to the engine during deceleration of the vehicle;
When the fuel cut is executed by the fuel cut control means and the lockup clutch is in one of an engaged state and a semi-engaged state, the determination result by the vehicle speed determining means and the slip Based on either the slip ratio of the torque converter calculated by the rate calculation means and the rotation speed of the input shaft of the automatic transmission detected by the input shaft rotation speed detection means, the engagement state or half of the lockup clutch is determined. An automatic transmission control device comprising: an engagement release unit that releases the engagement state. When the vehicle speed determining means determines that the vehicle speed has become equal to or less than the predetermined vehicle speed, the disengagement means has a slip ratio calculated by the slip ratio calculating means equal to or less than a predetermined slip ratio. Based on that, the engagement state or the semi-engagement state of the lock-up clutch is released,
When the vehicle speed determining means determines that the vehicle speed is faster than the predetermined vehicle speed, the lockup clutch is operated based on the fact that the rotational speed of the input shaft of the automatic transmission is equal to or lower than the predetermined rotational speed. The automatic transmission control device according to claim 1, wherein the engagement state or the semi-engagement state is released.   Based on at least one of a shift stage of the automatic transmission, an ON / OFF state of an air conditioner mounted on the vehicle, and a failure state of the antilock brake system, the predetermined vehicle speed, the predetermined rotation speed, and the 3. The automatic transmission control device according to claim 1, wherein a set value of the predetermined slip ratio is changed.

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