JP2012172761A - Control device of lock-up clutch for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device of lock-up clutch for vehicle performing learning control high in accuracy with respect to pressure difference defining engaging condition.SOLUTION: Since, in a steady traveling state, the pressure difference ΔP is gradually decreased from a point where the lock-up clutch 26 is engaged, and a learning control with respect to a pressure difference ΔP at a point at which the lock-up clutch 26 begins to slide is performed, the pressure difference ΔP in a transition period from a static friction condition of the lock-up clutch 26 to dynamic friction condition can be learned accurately, and the limit lock-up clutch capacity in the static friction condition can be defined suitably. Therefore, an electronic control unit 50 of the lock-up clutch for vehicle performing the learning control accurately with respect to the pressure difference ΔP defining the engaging condition can be provided.

Description

  The present invention relates to a control device for a lockup clutch for a vehicle, and more particularly to an improvement for improving the learning control accuracy of a differential pressure that determines the engagement state.

  2. Description of the Related Art A vehicle including a torque converter provided between an engine and a transmission and a lockup clutch that directly connects an input rotating member and an output rotating member in the torque converter by engagement is known. In addition, regarding such a lock-up clutch, a control device for a lock-up clutch for a vehicle that controls the hydraulic pressure (lock-up clutch differential pressure) that determines the engagement state has been proposed. For example, this is the lockup clutch control device for an automatic transmission described in Patent Document 1. According to this technique, it is determined whether the traveling road surface of the vehicle is a bad road based on the wheel speed detected by the wheel speed sensor, and the engagement state of the lockup clutch is controlled based on the determination result. Thus, it is possible to reduce vibration generated in the vehicle body as the vehicle travels on a rough road by controlling the lockup clutch.

JP 2008-298145 A

  Incidentally, as an embodiment of the conventional technique, there is a torque fuse control in a vehicle including a belt type continuously variable transmission, for example. That is, by controlling the engagement pressure so that the lock-up clutch slides against a sudden input torque such as overstepping on a rough road or the like, the lock-up clutch (torque converter) is controlled by the external input torque. Control that functions as a limiter (fuse) is known. In such control, it is required to slide the lock-up clutch sufficiently and sufficiently against the external input torque while suppressing the belt clamping pressure in the belt-type continuously variable transmission as much as possible. It is necessary to perform highly accurate learning control regarding the clutch differential pressure. However, the conventional learning control has a limit in improving accuracy. For this reason, development of a control device for a lockup clutch for a vehicle that performs highly accurate learning control regarding the differential pressure that determines the engagement state has been demanded.

  The present invention has been made against the background of the above circumstances, and an object of the present invention is to provide a control device for a lockup clutch for a vehicle that performs highly accurate learning control regarding a differential pressure that determines an engagement state. There is.

  In order to achieve such an object, the gist of the first invention is that a torque converter provided between an engine and a transmission, and an input rotating member and an output rotating member in the torque converter by engagement, In a vehicle equipped with a lockup clutch that is directly connected to the vehicle, a vehicle lockup clutch control device that learns a differential pressure that determines the engagement state of the lockup clutch. The differential pressure is gradually reduced from the state in which the clutch is engaged, and learning control is performed on the differential pressure when the lock-up clutch starts to slip.

  In this way, during steady running, the differential pressure is gradually reduced from the state in which the lock-up clutch is engaged, and learning control relating to the differential pressure at the time when the lock-up clutch starts to slide is performed. Therefore, the differential pressure at the time of transition of the lock-up clutch from the static friction state to the dynamic friction state can be learned with high accuracy, and the limit lock-up clutch capacity in the static friction state can be suitably determined. That is, it is possible to provide a vehicle lock-up clutch control device that performs highly accurate learning control on the differential pressure that determines the engagement state.

  Here, the gist of the second invention subordinate to the first invention is that, with respect to the learning control, the differential pressure is gradually reduced from the state in which the lockup clutch is engaged, and the lockup clutch is slipped. The first differential pressure at the beginning is compared with the second differential pressure at the time when the lockup clutch is engaged and the differential pressure is gradually increased from the released state. is there. In this way, more accurate learning control can be performed with respect to the differential pressure that determines the engagement state of the lockup clutch.

  Further, the gist of the third invention subordinate to the second invention is that, as a result of the comparison, it is determined that the first differential pressure is higher than the second differential pressure. Performs the learning control using the second differential pressure as a learning value. In this way, more accurate learning control can be performed with respect to the differential pressure that determines the engagement state of the lockup clutch.

It is a figure which shows roughly the structure of the power transmission path | route from the engine to a drive wheel in the vehicle with which this invention is applied suitably. FIG. 2 is a block diagram illustrating a main part of a control system provided for controlling a lockup clutch and the like in the vehicle of FIG. 1. FIG. 2 is a hydraulic circuit diagram showing a main part relating to belt clamping pressure control and speed ratio control of a continuously variable transmission, among hydraulic control circuits provided in the vehicle of FIG. 1. FIG. 2 is a hydraulic circuit diagram showing a main part related to operation control of a lockup clutch, etc., among hydraulic control circuits provided in the vehicle of FIG. FIG. 2 is a diagram showing an example of a shift map used when obtaining a target input rotation speed in shift control of a continuously variable transmission provided in the vehicle of FIG. 1. FIG. 2 is a diagram illustrating an example of a required hydraulic pressure map for determining a required hydraulic pressure according to a gear ratio or the like in the clamping pressure control of the continuously variable transmission provided in the vehicle of FIG. 1. FIG. 2 is a diagram illustrating an example of a map that is experimentally obtained and stored in advance for engine rotation speed and engine torque with the throttle valve opening in the vehicle of FIG. 1 as a parameter; It is a figure which shows an example of the map previously calculated | required experimentally as a predetermined operating characteristic of the torque converter with which the vehicle of FIG. 1 was equipped, and memorize | stored. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus with which the vehicle of FIG. 1 was equipped. It is the schematic explaining the torque fuse control performed by the electronic control apparatus with which the vehicle of FIG. 1 was equipped. FIG. 2 is a time chart for explaining changes in relation values when the engagement state of the lockup clutch is changed in the torque converter provided in the vehicle of FIG. 1. FIG. It is a flowchart explaining the principal part of the lockup clutch differential pressure learning control by the electronic control apparatus with which the vehicle of FIG. 1 was equipped.

  In the present invention, preferably, the transmission includes a driving pulley (input variable pulley) and a driven pulley (output variable pulley) whose effective diameter is variable, and between the driving pulley and the driven pulley. A belt type continuously variable transmission having a transmission belt wound around the belt. In such an aspect, when performing torque limiter control that causes the lockup clutch to function as an external input torque limiter, by determining the fastening force of the lockup clutch based on the differential pressure that is the result of the learning control, The lockup clutch can be slid as necessary and sufficiently with respect to the external input torque while suppressing the belt clamping pressure in the belt type continuously variable transmission as much as possible.

  Preferably, the learning control is performed every time the vehicle travels normally. Specifically, when the vehicle speed and the accelerator opening are substantially constant, the learning control is performed corresponding to the vehicle speed and the accelerator opening. Further, when the actual output torque (actual engine torque) or the target engine torque of the engine is substantially constant, the learning control is performed corresponding to the actual output torque or the target engine torque. Preferably, the result of the learning control is stored in a storage device for each steady running. That is, it is stored in the storage device in association with the corresponding vehicle speed and accelerator opening, actual output torque, target engine torque, or the like, and is updated each time new learning control is performed.

  Preferably, the result of the learning control is used for torque fuse control for controlling the engagement pressure so that the lockup clutch is slid with respect to a sudden input torque such as overstepping on a rough road or the like. . For example, the differential pressure as a result of the learning control is used as the differential pressure for suppressing the fastening force as much as possible while maintaining the engagement (lock-up state) of the lock-up clutch for the torque fuse control. . Specifically, a differential pressure command value for realizing a differential pressure as a result of the learning control is output to a hydraulic control circuit (an electromagnetic control valve that controls the lockup clutch differential pressure) in the torque fuse control.

  Preferably, as the engine, for example, a gasoline engine such as an internal combustion engine that generates power by combustion of fuel or a diesel engine or the like is preferably used, but another prime mover such as an electric motor is used in combination with the engine. You can also.

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

  FIG. 1 is a diagram schematically showing a configuration of a power transmission path from an engine 12 to drive wheels 24 in a vehicle 10 to which the present invention is preferably applied. In the vehicle 10 shown in FIG. 1, the power generated by the engine 12 is changed from a torque converter 14 as a fluid transmission device to a forward / reverse switching device 16 and a continuously variable transmission (CVT) 18 as a vehicle automatic transmission. The transmission gear 24 is transmitted to the left and right drive wheels 24 through the reduction gear device 20, the differential gear device 22, and the like.

  The torque converter 14 includes a pump impeller 14p connected to the crankshaft 13 of the engine 12 and a turbine connected to the forward / reverse switching device 16 via a turbine shaft 30 corresponding to an output side member of the torque converter 14. An impeller 14t and a stator impeller 14s that is prevented from rotating in one direction by a one-way clutch, and transmit power through the fluid between the pump impeller 14p and the turbine impeller 14t. It is like that. That is, in the torque converter 14 of the present embodiment, the pump impeller 14p corresponds to the input rotating member, and the turbine impeller 14t corresponds to the output rotating member, and the power of the engine 12 is continuously variable through the fluid. It is transmitted to the transmission 18 side. A lock-up clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t so as to directly connect between the pump impeller 14p and the turbine impeller 14t. Further, the pump impeller 14p is controlled to shift the continuously variable transmission 18, to generate a belt clamping pressure of the continuously variable transmission 18, to control the operation of the lockup clutch 26, or A mechanical oil pump 28 that is generated when the engine 12 is rotationally driven by a working hydraulic pressure serving as a source pressure for supplying lubricating oil to each portion is connected.

As is well known, the lockup clutch 26 has a differential pressure ΔP () between a hydraulic pressure P _ON in the engagement side oil chamber 14on and a hydraulic pressure P _OFF in the release side oil chamber 14off by a hydraulic control circuit 100 described later. = P _ON -P _OFF ) is a hydraulic friction clutch that is frictionally engaged with the front cover 14c (see FIG. 4). The operating state of the torque converter 14 is, for example, a so-called lockup release state (torque control state, lockup off) in which the differential pressure ΔP is negative and the lockup clutch 26 is released, and the differential pressure ΔP is zero or more. The lock-up clutch 26 is half-engaged with slip, so-called lock-up slip state (half-engaged state, slip state), and the differential pressure ΔP is set to the maximum value so that the lock-up clutch 26 is completely engaged. The so-called lock-up state (engaged state, lock-up on) is roughly divided into three states.

In the lock-up state, the lock-up clutch 26 is completely engaged, whereby the pump impeller 14p and the turbine impeller 14t are integrally rotated, and the power of the engine 12 is transmitted to the continuously variable transmission 18 side. Directly communicated to Further, in the lock-up slip state, the differential pressure ΔP is controlled so as to be engaged in a predetermined slip state, for example, an input / output rotational speed difference (that is, slip rotational speed (slip amount) = engine rotational speed N). _E —Turbine rotation speed N _T ) N _S is feedback-controlled so that when the vehicle 10 is driven (powered on), the turbine shaft 30 is rotated following the crankshaft 13 with a predetermined slip amount, while the vehicle When the engine is not driven (power off), the crankshaft 13 is rotated following the turbine shaft 30 with a predetermined slip amount.

  The lockup clutch 26 is preferably provided with a damper spring 27 for absorbing torque impact. By providing the damper spring 27, the rotational fluctuation of the rotating member on the engine 12 side and the rotational fluctuation of the rotating member on the continuously variable transmission 18 side as viewed from the lock-up clutch 26 are the above-described damper springs. There is a possibility that the phase is shifted by 27 strokes.

  The forward / reverse switching device 16 is mainly composed of a forward clutch C1 and a reverse brake B1 as a starting clutch and a double pinion type planetary gear device 16p. Here, the turbine shaft 30 of the torque converter 14 is integrally connected to the sun gear 16s of the planetary gear unit 16p. The input shaft 32 of the continuously variable transmission 18 is integrally connected to the carrier 16c of the planetary gear device 16p. Further, the carrier 16c and the sun gear 16s of the planetary gear device 16p are selectively connected via the forward clutch C1, and the ring gear 16r is selectively connected to the housing 34 as a non-rotating member via the reverse brake B1. It is supposed to be fixed to. The forward clutch C1 and the reverse brake B1 correspond to an intermittent device as a predetermined friction engagement device that transmits the power of the engine 12 to the drive wheel 24 side by engagement. These are hydraulic friction engagement devices that are frictionally engaged by a hydraulic cylinder.

  When the forward clutch C1 is engaged and the reverse brake B1 is released, the forward / reverse switching device 16 is brought into an integrally rotating state, whereby the turbine shaft 30 is directly connected to the input shaft 32, and the forward travel is performed. The power transmission path is established (achieved), and the driving force in the forward direction is transmitted to the continuously variable transmission 18 side. When the reverse brake B1 is engaged and the forward clutch C1 is released, the forward / reverse switching device 16 establishes (achieves) a reverse power transmission path, and the input shaft 32 The turbine shaft 30 is rotated in the reverse direction, and the driving force in the reverse direction is transmitted to the continuously variable transmission 18 side. When both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 16 enters a neutral state (power transmission cut-off state) in which power transmission is cut off.

The intake pipe 36 of the engine 12 is provided with an electronic throttle valve 40 for electrically controlling the intake air amount Q _AIR of the engine 12 using a throttle actuator 38. The throttle actuator 38 controls the output of the engine 12, that is, the engine output torque, by controlling the opening θ _TH of the electronic throttle valve 40 in accordance with a command from the electronic control unit 50 described later.

  The continuously variable transmission 18 is provided on a drive side pulley (input side variable pulley, primary pulley, primary sheave) 42 having a variable effective diameter, which is an input side member provided on the input shaft 32, and an output shaft 44. A driven pulley (output-side variable pulley, secondary pulley, secondary sheave) 46 having a variable effective diameter, which is an output side member, and a transmission belt 48 wound between these variable pulleys 42, 46. This is a belt type continuously variable transmission in which power is transmitted through frictional force between the variable pulleys 42 and 46 and the transmission belt 48.

The variable pulleys 42 and 46 are fixed rotating bodies 42 a and 46 a fixed to the input shaft 32 and the output shaft 44, respectively, and are not rotatable relative to the input shaft 32 and the output shaft 44. Movably movable bodies 42b and 46b, and a drive side hydraulic cylinder (primary pulley side hydraulic cylinder) 42c and a driven side hydraulic cylinder as hydraulic actuators that apply thrust to change the V groove width between them. (Secondary pulley side hydraulic cylinder) 46c. Then, the supply and discharge flow rate of the hydraulic oil to the drive side hydraulic cylinder 42c is controlled by a hydraulic control circuit 100, which will be described later, so that the V groove widths of the variable pulleys 42 and 46 change, and the transmission belt 48 The engagement diameter (effective diameter) is changed, and the gear ratio γ (= transmission input rotational speed N _IN / transmission output rotational speed N _OUT ) is continuously changed. Also, the secondary pulley pressure (hereinafter referred to as belt clamping pressure) Pd, which is the hydraulic pressure of the driven hydraulic cylinder 46c, is pressure-controlled by a hydraulic control circuit 100 described later, so that the transmission belt 48 does not slip. The belt clamping pressure is controlled. As a result of such control, a primary pulley pressure (hereinafter referred to as shift control pressure) Pin, which is the hydraulic pressure of the drive side hydraulic cylinder 42c, is generated.

  FIG. 2 is a block diagram for explaining a main part of a control system provided in the vehicle 10 of this embodiment in order to control the operation of the engine 12, the forward / reverse switching device 16, the continuously variable transmission 18, and the like. is there. As shown in FIG. 2, the vehicle 10 includes, for example, a vehicle lockup clutch that controls the shift control and belt clamping pressure control of the continuously variable transmission 18 and the release or engagement state of the lockup clutch 26. The electronic control device 50 including the control device is provided. The electronic control unit 50 includes a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like, for example, and the CPU stores a program stored in the ROM in advance using a temporary storage function of the RAM. Various controls of the vehicle 10 are executed by performing signal processing according to the above. That is, output control of the engine 12, shift control of the continuously variable transmission 18, belt clamping pressure control, torque capacity control of the lock-up clutch 26, and the like are executed. The engine control device for control of 12, the hydraulic control device for shift control of the continuously variable transmission 18, the hydraulic control device for hydraulic control of the lock-up clutch 26, and the like.

The electronic control unit 50 includes an engine that is, for example, the rotation angle (position) A _CR of the crankshaft 13 detected by the crankshaft rotation speed sensor 52 and the rotation speed of the crankshaft 13 (that is, the rotation speed of the engine 12). signal representative of the rotational speed N _E, a signal representative of the turbine speed N _T is the rotational speed of the turbine shaft 30 detected by a turbine rotational speed sensor 54, rotation of the input shaft 32 detected by the input shaft rotational speed sensor 56 A signal representing the transmission input rotational speed N _IN which is the speed (that is, the input rotational speed of the continuously variable transmission 18), and the rotational speed of the output shaft 44 corresponding to the vehicle speed V detected by the output shaft rotational speed sensor 58 (that is, signal representing the transmission output speed N _OUT is the output rotational speed) of the continuously variable transmission 18, before being detected by a throttle sensor 60 Signal representing the throttle valve opening theta _TH is a degree of opening of the electronic throttle valve 40, a signal representing the cooling water temperature TH _W of the engine 12 detected by a coolant temperature sensor 62, the detected hydraulic pressure controlled by the CVT fluid temperature sensor 64 A signal representing the hydraulic oil temperature TH _CVT , which is the temperature of the hydraulic oil in the circuit 100, and the operation of the accelerator pedal 68 as a requested acceleration amount (driver required amount) for the vehicle 10 by the driver detected by the accelerator opening sensor 66. signal representing the accelerator opening a _CC is the amount, a signal indicative of the intake air quantity Q _aIR of the engine 12 detected by an intake air amount sensor 70, the operation of the foot brake is a service brake, which is detected by a foot brake switch 72 A signal indicating the brake on B _ON when the foot brake pedal is operated indicating that the pedal is in the middle (depressing operation), lever position Lever position (operating position, shift position) of a shift lever 76 detected by Nsensa 74 a signal representative of the P _SH, signals and the like representing the acceleration G of the vehicle 10 detected by the acceleration sensor 77 is adapted to be supplied Yes.

Further, the electronic control device 50 outputs a control command for controlling the operation of each part in the vehicle 10. For example, as an engine output control command signal S _E for controlling the output of the engine 12, a drive signal to the throttle actuator 38 for controlling the opening / closing of the electronic throttle valve 40, and the fuel injected from the fuel injection device 78 An injection signal for controlling the amount, an ignition timing signal for controlling the ignition timing of the engine 12 by the ignition device 80, and the like are output. Further, in order to drive the shift control command signal S _T for example a solenoid valve for controlling the flow of hydraulic fluid to said drive side hydraulic cylinder 42c DS1 and the solenoid valve DS2 for varying the speed ratio γ of the continuously variable transmission 18 , A clamping pressure control command signal S _B for adjusting the clamping pressure of the transmission belt 48, for example, a hydraulic pressure command signal for driving the linear solenoid valve SLS for regulating the belt clamping pressure Pd is output. Further, the engagement of the lock-up clutch 26, release, slip N _S as a lock-up control command signal S _L for controlling, for example, lock-up switching for switching the valve position of the relay valve 124 in the hydraulic control circuit 100 hydraulic pressure command signal and the like for driving the hydraulic pressure command signal and said lock torque capacity T slip control linear solenoid valve _C to adjust the SLU up clutch 26 for driving the solenoid valve SL is output. In addition, a hydraulic pressure command signal for driving a linear solenoid valve that regulates the line hydraulic pressure P _L is output to a hydraulic pressure control circuit 100 described later.

  The shift lever 76 is disposed, for example, in the vicinity of the driver's seat, and is one of five lever positions “P”, “R”, “N”, “D”, and “L” that are sequentially positioned. It is designed to be manually operated. The “P” position releases the power transmission path of the vehicle 10, that is, a neutral state (neutral state) in which the power transmission of the vehicle 10 is interrupted, and mechanically prevents the rotation of the output shaft 44 by a mechanical parking mechanism ( This is a parking position (position) for locking. The “R” position is a reverse travel position (position) for making the rotation direction of the output shaft 44 reverse. Further, the “N” position is a neutral position (position) for achieving a neutral state in which the power transmission of the vehicle 10 is interrupted. The “D” position is a forward travel position (position) for executing the automatic shift control by establishing the automatic shift mode within the shift range that allows the continuously variable transmission 18 to shift. The “L” position is an engine brake position (position) for applying a strong engine brake. As described above, the “P” position and the “N” position are non-traveling positions that are selected when the power transmission path is in the neutral state and the vehicle is not traveling, and are “R” position, “D” position, and “L”. The position is a travel position that is selected when the vehicle 10 travels with the power transmission path in a power transmission enabled state that enables power transmission through the power transmission path.

  FIG. 3 is a hydraulic circuit diagram showing a main part relating to belt clamping pressure control and speed ratio control of the continuously variable transmission 18 in the hydraulic control circuit 100 provided in the vehicle 10. FIG. 4 is a hydraulic circuit diagram showing a main part of the hydraulic control circuit 100 related to operation control of the lockup clutch 26 and the like. As shown in FIG. 3, the hydraulic control circuit 100 is a transmission ratio control that functions as a transmission control valve that controls the flow rate of hydraulic oil to the drive hydraulic cylinder 42c so that the transmission ratio γ is continuously changed. A valve UP 116, a transmission ratio control valve DN118, a clamping pressure control valve 120 that regulates a belt clamping pressure Pd that is the hydraulic pressure of the driven hydraulic cylinder 46c so that the transmission belt 48 does not slip, and the forward clutch C1; A manual valve 122 or the like that mechanically switches the oil path according to the operation of the shift lever 76 is provided so that the reverse brake B1 is engaged or released.

Here, the first line oil pressure P _L1 in the oil pressure control circuit 100 is, for example, relief using, for example, the working oil pressure output (generated) from the mechanical oil pump 28 rotated by the engine 12 as a source pressure. Type primary regulator valve (first line hydraulic pressure regulating valve) 110 is adjusted to a value corresponding to the input torque T _{IN and the} like to the continuously variable transmission 18 based on the control hydraulic pressure which is the output hydraulic pressure of the linear solenoid valve. It is like that. The second line oil pressure P _L2 in the oil pressure control circuit 100 is based on the oil pressure discharged from the primary regulator valve 110 for adjusting the first line oil pressure P _L1 by the primary regulator valve 110, for example. For example, the pressure is regulated by a relief type secondary regulator valve (second line hydraulic pressure regulating valve) 112 based on a control hydraulic pressure that is an output hydraulic pressure of the linear solenoid valve. Moreover, modulator pressure P _M of the hydraulic control circuit 100 is pressure regulated to a constant pressure based on the control oil pressure which is the output oil pressure of the linear solenoid valve by the modulator valve 114 as source pressure for example the first line pressure P _L1 It is like that.

The transmission ratio control valve UP116 is provided so as to be movable in the axial direction, thereby opening and closing the input / output port 116t and the input / output port 116i, and the spool valve element 116a to and from the input / output port 116t. A spring 116b as an urging means for urging in a direction in which the port 116i communicates, and a thrust in a direction in which the spring 116b is accommodated and the input / output port 116t and the input / output port 116i communicate with the spool valve element 116a. The oil chamber 116c that receives the control hydraulic pressure _PS2 that is the output hydraulic pressure of the solenoid valve DS2 that is duty-controlled by the electronic control unit 50 to apply, and the thrust in the direction that closes the input / output port 116i to the spool valve element 116a By the electronic control unit 50 to give An oil chamber 116d that receives the control oil pressure P _S1 is output hydraulic pressure of the solenoid valve DS1 that is Yuti controlled includes. The transmission ratio control valve DN118 is provided so as to be movable in the axial direction, and serves as a spool valve element 118a that opens and closes the input / output port 118t, and an urging means that urges the spool valve element 118a in the valve closing direction. A spring 118b, an oil chamber 118c that receives the spring 118b and receives the control hydraulic pressure _PS1 to apply a thrust in the valve closing direction to the spool valve element 118a, and a thrust in the valve opening direction to the spool valve element 118a And an oil chamber 118d for receiving the control oil pressure P _S2 .

The solenoid valve DS1 supplies hydraulic fluid to the drive side hydraulic cylinder 42c to increase its hydraulic pressure and reduce the V groove width of the drive side pulley 42 to reduce the speed ratio γ, that is, control to the upshift side. Therefore, the control hydraulic pressure P _S1 is output. Further, the solenoid valve DS2 discharges the hydraulic oil in the drive side hydraulic cylinder 42c, lowers its hydraulic pressure, increases the V groove width of the drive side pulley 42, and increases the speed ratio γ, that is, downshift side. The control hydraulic pressure P _S2 is output for control. Specifically, when the control hydraulic pressure P _S1 is output, the first line hydraulic pressure P _L1 input to the supply port 116s of the transmission ratio control valve UP116 is supplied to the drive side hydraulic cylinder 42c via the input / output port 116t. As a result, the shift control pressure Pin is continuously controlled. When the control oil pressure P _S2 is output, the hydraulic oil in the drive side hydraulic cylinder 42c is discharged from the discharge port 118x via the input / output port 116t, the input / output port 116i, and the input / output port 118t, resulting in a shift. The control pressure Pin is continuously controlled. For example, as shown in FIG. 5, the relationship between the vehicle speed V and the target transmission input rotational speed N _IN ^* that are experimentally obtained and stored in advance using the accelerator operation amount A _CC corresponding to the driver's acceleration request amount as a parameter. The rotation deviation ΔN _IN (= N _IN ^* −N _IN ) is set so that the actual transmission input rotation speed N _IN matches the target transmission input rotation speed N _IN ^* calculated according to the (shift map). Accordingly, the continuously variable transmission 18 is shift-controlled, that is, the shift control pressure Pin is controlled by supplying and discharging hydraulic oil to and from the drive side hydraulic cylinder 42c, and the speed ratio γ is continuously changed. The shift map in FIG. 5 corresponds to the shift conditions, and the target transmission input rotational speed N _IN ^* is set such that the larger the vehicle speed V is and the larger the accelerator opening degree A _CC is, the larger the gear ratio γ is. . Further, the vehicle speed V corresponds to the transmission output speed N _OUT, the target transmission input rotation speed N _IN ^* is a target value of the transmission input rotational speed N _IN corresponds to the target speed ratio, the continuously variable transmission It is determined within the range of the minimum speed ratio γmin and the maximum speed ratio γmax of the machine 18.

The clamping pressure control valve 120 is, for example, a spool valve element 120a that opens and closes the output port 120t by being provided so as to be movable in the axial direction, and a spring as a biasing means that biases the spool valve element 120a in the valve opening direction. 120b and a control oil pressure P _SLS that is an output oil pressure of the linear solenoid valve SLS that is duty-controlled by the electronic control unit 50 in order to accommodate the spring 120b and apply a thrust in the valve opening direction to the spool valve element 120a. An oil chamber 120c for receiving and a feedback oil chamber 120d for receiving the belt clamping pressure Pd output for applying thrust in the valve closing direction to the spool valve element 120a are provided. Then, the clamping force control valve 120, the continuously variable transmission corresponding to the continuous tone pressure control to transmit the torque control hydraulic pressure P _SLS first line pressure P _L1 as a pilot pressure of the linear solenoid valve SLS 18 The belt clamping pressure Pd corresponding to the input torque T _IN or the like is output. For example, as shown in FIG. 6, the transmission ratio γ and the required hydraulic pressure (target belt clamping pressure), which are experimentally obtained and stored in advance so that belt slip does not occur, using the input torque T _IN of the continuously variable transmission 18 as a parameter. The belt clamping pressure Pd to the driven hydraulic cylinder 46c is regulated according to the relationship with Pd ^* (belt clamping pressure map), and the belt clamping pressure, that is, both the variable pulleys 42, according to the belt clamping pressure Pd, The frictional force between 46 and the transmission belt 48 is increased or decreased. The belt clamping pressure Pd in the driven hydraulic cylinder 46c, which is the output hydraulic pressure of the clamping pressure control valve 120, is detected by, for example, a hydraulic sensor 120s.

The input torque T _IN of the continuously variable transmission 18 used when adjusting the belt clamping pressure Pd is, for example, the engine torque _TE to the torque ratio t of the torque converter 14 (= the output torque of the torque converter 14 (hereinafter referred to as the turbine). It is calculated by the electronic control unit 50 as an input torque (hereinafter referred to as the pump torque T _P)) obtained by multiplying the torque (= T _E × t) of the torque T _T as) / torque converter 14. This engine torque T _E is obtained in advance between the engine rotational speed N _E and the engine torque T _{E using} , for example, the intake air amount Q _AIR (or the corresponding throttle valve opening θ _TH or the like) as a required load for the engine 12 as a parameter. The electronic control unit calculates the estimated engine torque T _E es based on the intake air amount Q _AIR and the engine rotation speed N _E from the relationship (map, engine torque characteristic diagram) shown in FIG. 50. Alternatively, as the engine torque T _E , for example, an actual output torque (actual engine torque) T _{E of the} engine 12 detected by a torque sensor or the like may be used. The torque ratio t of the torque converter 14 is the speed ratio e of the torque converter 14 (= output rotational speed of the torque converter 14 (hereinafter referred to as turbine rotational speed _NT ) / input rotational speed of the torque converter 14 (hereinafter referred to as pump rotation). FIG. 8 is a function of a speed N _P (referred to as engine speed N _E )), for example, a speed ratio e, a torque ratio t, an efficiency η, and a capacity coefficient C, which are obtained experimentally and stored in advance. Is calculated by the electronic control unit 50 on the basis of the actual speed ratio e from the relationship shown in FIG. (Map, predetermined operating characteristic diagram of the torque converter 14). The estimated engine torque T _E es is calculated so as to represent the actual engine torque T _E itself, and unless otherwise distinguished from the actual engine torque T _E , the estimated engine torque T _E es is converted to the actual engine torque T _E es. it is assumed that the handling of as a T _E. Therefore, the estimated engine torque T _E es includes the actual engine torque T _E.

Wherein the manual valve 122, modulator pressure P _M is pressure regulated to a constant pressure by the input port 122a for example the modulator valve 114 is supplied. Then, the shift lever 76 is operated to the "D" position or "L" position, modulator pressure P _M is supplied to the forward clutch C1 via a forward output port 122f as forward running output pressure and the The oil passage of the manual valve 122 is switched so that the hydraulic oil in the reverse brake B1 is drained (discharged) to the atmospheric pressure, for example, from the reverse output port 122r through the discharge port EX, and the forward clutch C1 is engaged. And the reverse brake B1 is released.

Further, the shift lever 76 is operated to the "R" position, modulator pressure P _M is supplied to the reverse brake B1 via the reverse output port 122r as reverse running output pressure and the forward clutch C1 The oil passage of the manual valve 122 is switched so that the hydraulic oil is drained (discharged) from the forward output port 122f to the atmospheric pressure, for example, via the discharge port EX, and the reverse brake B1 is engaged. At the same time, the forward clutch C1 is released.

  Further, when the shift lever 76 is operated to the “P” position or the “N” position, an oil passage from the input port 122a to the forward output port 122f and from the input port 122a to the reverse output port 122r. The oil passage of the manual valve 122 is switched so that the hydraulic oil in the forward clutch C1 and the reverse brake B1 are all drained from the manual valve 122, and the forward passage Both the clutch C1 and the reverse brake B1 are released.

As shown in FIG. 4, the hydraulic pressure control circuit 100 is turned on / off by an on / off signal corresponding to an SL instruction (SL command) signal S _SL supplied from the electronic control unit 50, for example, and is used as a switching signal pressure P _SL. A switching solenoid valve SL for generating a lockup, a lockup relay valve 124 for switching between the released state and the engaged or slipped state of the lockup clutch 26, and a lockup clutch pressure command supplied from the electronic control unit 50 A slip-up linear solenoid valve SLU that outputs a signal pressure P _SLU corresponding to a drive current I _SLU corresponding to a value (LU clutch pressure command value, SLU indicated pressure) S _SLU , and a lock-up clutch by the lock-up relay valve 124 The lock according to the signal pressure P _SLU when 26 is engaged or slipped Up clutch 26 slip N _S control or for engaging the lockup clutch 26 (i.e. for switching the operating state of the lockup clutch 26 in the range of the slip state to the lock-up on) the lock-up control valve 126 and an oil cooler 128 for cooling the hydraulic oil.

The lock-up relay valve 124 has a spool 130 for switching the connection state, the release side position for a released state of the lock-up clutch 26 in response to the switching signal pressure P _SL (off-side position) thereof The lockup clutch 26 is switched to an engaged position (on-side position) where the lockup clutch 26 is engaged or slipped. FIG. 4 shows a state in which the spool valve element 130 is located at an off-side position (OFF) where the lock-up clutch 26 is disengaged on the left side from the center line. The state where the spool valve element 130 is located at the on-side position (ON) in the slip state is shown. Specifically, the lockup relay valve 124 includes a release side port 132 that communicates with the release side oil chamber 14off, an engagement side port 134 that communicates with the engagement side oil chamber 14on, and a second line oil pressure P _L2. When the lock-up clutch 26 is released, the hydraulic oil in the engagement-side oil chamber 14on is drained and discharged from the secondary regulator valve 112 when the lock-up clutch 26 is engaged. A discharge port 138 through which the discharged hydraulic oil (P _REL ) is discharged, a bypass port 140 through which the hydraulic oil in the release-side oil chamber 14off is discharged when the lockup clutch 26 is engaged, and the secondary regulator valve 112 hydraulic fluid is allowed to flow out (P _REL) and a relief port 142 which is fed off-side position of the spool 130 A spring 144 for urging towards, an oil chamber 146 for receiving a switching signal pressure P _SL from the switching solenoid valve SL in the end face of the spool 130, and.

The lock-up control valve 126 includes a spool valve element 148, a spring 150 for biasing the spool valve element 148 toward the slip (SLIP) side position, and the spool valve element 148 toward the slip side. an oil chamber 152 for receiving the hydraulic pressure P _oN in the engagement side oil chamber 14on the torque converter 14 in order to urge, to bias toward the spool 148 to complete engagement (oN) side position An oil chamber 154 that receives the hydraulic pressure P _OFF in the release side oil chamber 14off of the torque converter 14, an oil chamber 156 that is supplied with the signal pressure P _SLU output from the slip control linear solenoid valve SLU, and a second line The hydraulic pressure output from the input port 158 to which the hydraulic pressure P _L2 is supplied and the bypass port 140 of the lockup relay valve 124 is A control port 160 to be supplied. FIG. 4 shows a state in which the spool valve element 148 is located at the slip (SLIP) side position on the left side from the center line, and the spool is located on the right side of the center line at the complete engagement (ON) side position. The state in which the valve element 148 is located is shown.

The slip control linear solenoid valve SLU outputs a signal pressure P _SLU for controlling the engagement pressure during engagement or slip engagement of the lockup clutch 26 in accordance with a command from the electronic control unit 50. is there. For example, the modulator pressure P _M and the original pressure, an electromagnetic control valve which outputs a signal pressure P _SLU under reduced pressure the modulator pressure P _M, the electronic control unit LU clutch pressure command value is supplied from the 50 S _SLU A signal pressure P _SLU proportional to the drive current (excitation current) I _SLU corresponding to is generated. Further, since the drain port 162 of the slip control linear solenoid valve SLU communicates with the check ball 164, the drain port 162 is always blocked by the check ball 164, and when a pressure exceeding a predetermined value is applied to the check ball 164. The hydraulic oil is discharged by opening the valve.

The switching solenoid valve SL outputs a predetermined switching signal pressure P _SL in accordance with an SL command signal (ON / OFF signal) S _SL from the electronic control unit 50. For example, it de-energized state (off state), the switching signal pressure P _SL is a drain pressure, to be applied to the oil chamber 146 to the energized state (ON state) switching signal pressure P _SL as a modulator pressure P _M Thus, the spool valve element 130 of the lockup relay valve 124 is moved to the ON position (ON) in the engaged state.

The operating state of the lockup clutch 26 is switched by switching the supply state of the operating oil pressure to the engagement side oil chamber 14on and the release side oil chamber 14off by the hydraulic control circuit 100 configured as described above. The First, the case where the lock-up clutch 26 is slipped or locked up will be described. In the lockup relay valve 124, when the switching signal pressure P _SL is supplied to the oil chamber 146 by the switching solenoid valve SL and the spool valve element 130 is biased to the on-side position, the input port 136. the second line pressure P _L2 supplied is supplied from the engagement-side port 134 to the engaging-side oil chamber 14on the. The second line oil pressure P _L2 supplied to the engagement side oil chamber 14on becomes the oil pressure P _ON . At the same time, the release-side oil chamber 14off is communicated from the release-side port 132 to the control port 160 of the lockup control valve 126 via the bypass port 140. Then, the hydraulic pressure P _OFF in the release side oil chamber 14off is adjusted by the lockup control valve 126 (that is, the differential pressure ΔP (= P _ON −P _OFF ), that is, the engagement pressure is adjusted by the lockup control valve 126. The operation state of the lock-up clutch 26 is switched in the range from the slip state to the lock-up on.

Specifically, when the spool valve element 130 of the lockup relay valve 124 is biased to the engaged (ON) position, that is, when the lockup clutch 26 is switched to the engaged or slipped state. Further, the signal pressure P _SLU for urging the spool valve element 148 to the fully engaged (ON) side position in the lockup control valve 126 is not supplied to the oil chamber 156, and the thrust of the spring 150 When the spool valve element 148 is set to the slip (SLIP) side position, the second line hydraulic pressure P _L2 supplied to the input port 158 is released from the release port 132 via the bypass port 140 from the control port 160. It is supplied to the side oil chamber 14off. The flow rate of hydraulic oil output from the control port 160 is controlled by the signal pressure P _SLU supplied to the oil chamber 156. That is, in the state where the spool valve element 148 is in the slip (SLIP) side position, the differential pressure ΔP is controlled by the signal pressure P _{SLU of the} slip control linear solenoid valve SLU, and the slip state of the lockup clutch 26 is reached. (Fastening force) is controlled.

Further, when the spool valve element 130 of the lockup relay valve 124 is urged to the ON position, the spool valve element 148 is urged to the fully engaged (ON) position in the lockup control valve 126. When the signal pressure P _SLU to be supplied is supplied to the oil chamber 156, the second line oil pressure P _L2 is not supplied from the input port 158 to the release-side oil chamber 14off, and from the release-side oil chamber 14off. The hydraulic oil is discharged from the drain port EX. As a result, the differential pressure ΔP is maximized and the lockup clutch 26 is fully engaged. Further, when the lockup clutch 26 is in a slip state or a completely engaged state, the lockup relay valve 124 is positioned at the on-side position, so that the relief port 142 and the discharge port 138 are communicated with each other. As a result, the hydraulic oil (P _REL ) discharged from the secondary regulator valve 112 is supplied from the discharge port 138 to the oil cooler 128.

On the other hand, in the lockup relay valve 124, when the switching signal pressure P _SL is not supplied to the oil chamber 146 and the spool valve element 130 is positioned to the off-side position by the urging force of the spring 144, the input The second line oil pressure P _L2 supplied to the port 136 is supplied from the release side port 132 to the release side oil chamber 14off. The hydraulic oil discharged to the engagement side port 134 through the engagement side oil chamber 14on is supplied from the discharge port 138 to the oil cooler 128 and cooled. That is, in a state where the spool valve element 130 of the lockup relay valve 124 is positioned to the off-side position, the lockup clutch 26 is released, and the slip control linear solenoid valve SLU or the lockup control is performed. Slip or engagement control through the valve 126 is not performed. In other words, even when the signal pressure P _SLU output from the slip control linear solenoid valve SLU is changed, the spool valve element 130 of the lock-up relay valve 124 is moved to the off-side position. The change is not reflected in the engagement state (differential pressure ΔP) of the lock-up clutch 26 as long as it is. Note that the differential pressure ΔP controlled by the signal pressure P _{SLU of the} slip control linear solenoid valve SLU is also a lockup clutch pressure _PLU as a hydraulic pressure value indicating an engaged or disengaged state of the lockup clutch 26. Further, the lock-up clutch pressure P _LU is also the oil pressure value corresponding to the torque capacity T _C of the slip amount N _S and the lock-up clutch 26. Further, the signal pressure P _SLU of LU clutch pressure command value S _SLU and the slip control linear solenoid valve SLU is a hydraulic command value of the lock-up clutch pressure P _LU.

FIG. 9 is a functional block diagram for explaining a main part of the control function by the electronic control unit 50. The engine output control means 82 shown in FIG. 9 uses, for example, a throttle signal, an injection signal, an ignition timing signal, etc. as the engine output control command signal S _E for controlling the output of the engine 12, for example, the throttle actuator 38, the fuel injection. It outputs to the apparatus 78, the ignition device 80, etc. For example, the target throttle valve opening θ _TH ^* is set to the throttle opening θ _TH for obtaining the target engine torque T _E ^* corresponding to the accelerator opening A _CC, and the throttle is set so that the target engine torque T _E ^* is obtained. In addition to controlling the opening and closing of the electronic throttle valve 40 by the actuator 38, the fuel injection amount is controlled by the fuel injection device 78, and the ignition timing is controlled by the ignition device 80.

The shift control means 84, for example, from the shift map as shown in FIG. 5, based on the vehicle state indicated by the actual vehicle speed V and the accelerator opening degree A _CC , the target transmission input rotation speed N _IN of the transmission input rotation speed N _IN. Set ^* . Then, the actual transmission input rotational speed N _IN is rotated deviation between the to coincide with the target transmission input rotation speed N _IN ^*, for example, the actual transmission input rotational speed N _IN and the target transmission input rotation speed N _IN ^* Based on ΔN _IN (= N _IN ^* −N _IN ), the continuously variable transmission 18 is shifted by, for example, feedback control. That is, the shift control means 84, shift control for changing the V groove widths of both variable pulleys 42 and 46 by controlling the flow of hydraulic fluid to said drive side hydraulic cylinder 42c based on the rotation deviation .DELTA.N _IN command signal determines the (hydraulic pressure command) S _T, continuously changing the speed ratio γ and outputs the shift control command signal S _T to the hydraulic control circuit 100. Wherein the hydraulic control circuit 100, so that the shift of the continuously variable transmission 18 according to the shift control command signal S _T from the shift control means 84 is executed, the solenoid valve DS1 and the solenoid valve DS2 is is actuated The shift control pressure Pin is adjusted by supplying and discharging the hydraulic oil to and from the drive side hydraulic cylinder 42c.

The belt clamping pressure control means 86, for example, from the belt clamping pressure map as shown in FIG. 6, the input torque T _IN (= engine torque T _E × torque ratio t: T _E of the continuously variable transmission 18 is estimated engine torque T, for example. _E es) and the actual gear ratio γ (= N _IN / N _OUT ), the target belt clamping pressure Pd ^* is set based on the vehicle state. Then, it outputs the target belt clamping pressure Pd ^* is squeezing force control command signal S _B for pressure regulates the belt clamping pressure Pd of the driven-side hydraulic cylinder 46c so as to obtain to the hydraulic control circuit 100. In the hydraulic control circuit 100, the clamping pressure control command signal S said linear solenoid valve SLS is actuated belt clamping pressure Pd as the belt clamping pressure Pd is increased or decreased in accordance with _B from the belt clamping pressure control unit 86 It is regulated. Thus, the belt clamping pressure control means 86 operates the linear solenoid valve SLS in accordance with the input torque T _IN of the continuously variable transmission 18 to control the belt clamping pressure Pd, thereby generating belt slip. The belt clamping pressure is controlled so that it is as low as possible in order to improve fuel efficiency.

The lock-up clutch control means 88 basically includes a lock-up release (lock-up off) region, a slip control region (lock-up slip control operation region), lock-up control using the throttle valve opening θ _TH and the vehicle speed V as variables. The lockup is based on the actual throttle valve opening θ _TH and the vehicle state indicated by the vehicle speed V from a previously stored relationship (not shown) (map, lockup region diagram) having an operation region (lockup on) region. The switching of the operating state of the clutch 26 is controlled. For example, it is determined from the lockup region diagram whether the lockup release region, the lockup slip control operation region, or the lockup control operation region of the lockup clutch 26 based on the actual vehicle state, the lockup control command signal S _L for switching to the switching or lock-up slip control operation to lock-up control operation of the lock-up release of the lockup clutch 26 outputs to the hydraulic control circuit 100. Further, the lock-up clutch control unit 88 determines that a lock-up slip control execution region, sequentially calculates an actual slip amount N _S of the lock-up clutch 26, the actual slip amount N _S is the target slip A lockup control command signal S _L for controlling the differential pressure ΔP so as to be the amount N _S ^* is output to the hydraulic pressure control circuit 100.

The hydraulic in the control circuit 100, the lock-up control instruction signal S _L in accordance with the lock-up the switching solenoid valve SL as release and the slipping state to the engagement are switched clutch 26 from the lock-up clutch control unit 88 Is operated to switch the valve position of the lock-up relay valve 124 between a release side (OFF) position and an engagement side (ON) position. Further, as the torque capacity T _C at the slip state to the engagement of the lock-up clutch 26 is increased or decreased through the lock-up control valve 126 according to the lock-up control command signal S _L from the lock-up clutch control unit 88 slip amount N _S of the slip control linear solenoid valve SLU said is actuated lock-up clutch 26 or engaged its lockup clutch 26 is controlled. For example, in a relatively high vehicle speed region, the lock-up clutch 26 is locked up (completely engaged), and the pump impeller 14p and the turbine impeller 14t are directly connected, so that the torque converter 14 slips. Loss (internal loss) is reduced and fuel efficiency is improved. Further, in a relatively low / medium speed region, slip control (lock-up slip control) is performed in which a predetermined minute slip is applied between the pump impeller 14p and the turbine impeller 14t. Thus, the lock-up operation region is expanded, the transmission efficiency of the torque converter 14 is improved, and the fuel consumption is improved.

Here, while the vehicle 10 is traveling, there may be a case where the vehicle 10 passes a step on the road surface such as unevenness. When the driving wheel 24 hits such a step, the rotation of the driving wheel 24 is temporarily stopped, so that the rotation of the rotating member constituting the continuously variable transmission 18 is also temporarily stopped. That is, as a reverse input from the drive wheel 24 side to the continuously variable transmission 18 side, for example, a reverse input torque (impact torque) from the drive wheel 24 side is temporarily input. The lock-up clutch control means 88 preferably controls the lock-up clutch by controlling the engagement pressure (differential pressure ΔP) so that the lock-up clutch 26 slides with respect to the reverse input torque. Torque fuse control is performed to cause the 26 through the torque converter 14 to function as a reverse input torque limiter (fuse). FIG. 10 is a schematic diagram for explaining such torque fuse control. As shown in this figure, considering the state in which slip (slip) may occur in the lockup clutch 26, the engine side inertia moment I _e in the drive system from the engine 12 to the pump impeller 14p of the torque converter 14 is shown. (Corresponding to the rotational speed ω _e of the crankshaft 13) and the CVT first-axis inertia moment I ₁ (input shaft) in the drive system from the turbine impeller 14t of the torque converter 14 to the drive pulley 42 (input shaft 32). 32 corresponding to the rotational speed ω ₁ ). Here, as shown in FIG. 10, when reverse input torque is input from the output shaft 44 side, the reverse input torque may cause the transmission belt 48 of the torque converter 14 to slip. By sliding the lock-up clutch 26 before the 48 slips, the reverse input torque is eliminated, and the slippage of the transmission belt 48 is suppressed. Further, since the durability of the device is not affected by the slip of the lock-up clutch 26, there is an advantage that the durability of the device can be improved by the torque fuse control.

As the torque fuse control, the lockup clutch control means 88 performs the lockup with a torque capacity T _C (target torque capacity T _C ^* ) as low as possible within a limit where the lockup clutch 26 does not slip, for example. A lockup control command signal S _L for controlling the differential pressure ΔP that realizes the torque capacity T _C is output to the hydraulic control circuit 100 so that the clutch 26 is engaged. For the determination of this differential pressure ΔP, the result of learning control by differential pressure learning control means 92 described later stored in the storage device 94 is used. This learning control and its result will be described in detail below together with the explanation of the learning control by the differential pressure learning control means 92.

The steady running determination means 90 determines whether or not the vehicle 10 is running steady. For example, the vehicle speed V corresponding to the transmission output rotational speed N _OUT which is the rotational speed of the output shaft 44 detected by the output shaft rotational speed sensor 58 (that is, the output rotational speed of the continuously variable transmission 18) is substantially constant. There, when the accelerator opening a _CC is substantially constant is and the operation amount of the accelerator pedal 68 detected by the accelerator opening sensor 66, determines that said vehicle 10 is performing a steady running. Also, preferably, the actual output torque of said engine 12 is a function of the engine rotational speed N _E detected by the electronic throttle valve opening theta _TH and the crankshaft rotational speed sensor 52 which is detected by a throttle sensor 60 ( When the target engine torque T _E ^* corresponding to the actual engine torque T _E or the accelerator opening degree A _CC is substantially constant, it is determined that the vehicle 10 is in steady running. Here, the vehicle speed V to the accelerator opening degree A _CC or the like is substantially constant, for example, when a change within a specified time is within a predetermined numerical range, or with a time change rate dV / dt, dA _CC / dt. Etc. are within the prescribed range.

The differential pressure learning control unit 92 determines the engagement state of the lockup clutch 26 when the determination of the steady traveling determination unit 90 is affirmative, that is, when it is determined that the vehicle 10 is performing steady traveling. Learning control related to the determined differential pressure ΔP is performed. Specifically, the differential pressure ΔP is gradually decreased from the state in which the lockup clutch 26 is engaged (lockup state), and when the lockup clutch 26 starts to slide (the engine rotational speed _NE and the turbine rotational speed). Learning control related to the differential pressure ΔP at the time when a difference with N _T occurs. Preferably, a lockup control command signal S _L (for example, a signal pressure command of the linear solenoid valve SLU for slip control) corresponding to (defines the differential pressure ΔP) corresponding to the differential pressure ΔP when the lockup clutch 26 starts to slip. Value) as a learning value, and the learning control is performed. Further, in the configuration provided with a hydraulic sensor for detecting the hydraulic pressure supplied to each of the engagement side oil chamber 14on and the release side oil chamber 14off of the torque converter 14, the differential pressure when the lockup clutch 26 starts to slide. may be one that performs the learning control [Delta] P itself as the learned value, and performs the learning control the differential pressure [Delta] P is a value obtained by adding a constant K _a ΔP + K _a as the learned value, the differential pressure [Delta] P The learning control may be performed using ΔP × K _b which is a value obtained by multiplying the constant K _b by the learning value.

The differential pressure learning control unit 92 preferably performs the learning control corresponding to each steady travel every time the steady travel determination unit 90 determines the steady travel. In other words, preferably, each time the steady running in which the vehicle speed V and the accelerator opening degree A _CC are substantially constant is determined, the learning control is performed corresponding to each vehicle speed V and the accelerator opening degree A _CC . Also, preferably, the actual output torque of said engine 12 is a function of the engine rotational speed N _E detected by the electronic throttle valve opening theta _TH and the crankshaft rotational speed sensor 52 which is detected by a throttle sensor 60 ( Learning control is executed for each target engine torque T _E ^* corresponding to the actual engine torque T _E or the accelerator opening degree A _CC . Then, the result of the learning control by the differential pressure learning control means 92 is associated with the corresponding vehicle speed V and accelerator opening A _CC , actual output torque T _E or target engine torque T _E ^*, etc. 94 and updated whenever new learning control is performed.

FIG. 11 is a time chart for explaining the change of each relational value when the engagement state of the lockup clutch 26 is changed in the torque converter 14. In the example shown in FIG. 11, the differential pressure ΔP, that is, the lock-up differential pressure command value is gradually decreased from the state in which the lock-up clutch 26 is engaged, and the lock-up clutch 26 starts to slip at time t1 (ie, , difference occurs in the turbine speed N _T and the engine rotational speed N _E). Further, after the lockup differential pressure command value is gradually decreased from the time point t1 to the time point t2, the lockup differential pressure command value starts increasing from the time point t2 and is gradually increased to the time point t3. lockup clutch 26 is engaged (i.e., are gone difference between the turbine rotational speed N _T and the engine rotational speed N _E). That is, the lock-up clutch 26 is engaged (lock-up on) until time t1, and the lock-up clutch 26 is slipped (half-engaged) from time t1 to time t3. The lockup clutch 26 is engaged again after time t3.

  Here, in general, the static friction coefficient (static friction coefficient) related to the friction between the objects is larger than the dynamic friction coefficient. Also in FIG. 11, the dynamic friction coefficient between time t1 and time t3 is until time t1 or after time t3. It is smaller than the coefficient of static friction according to. That is, when it is considered to suppress the fastening force of the lockup clutch 26 as much as possible while maintaining the engaged state of the lockup clutch 26, the limit in the static friction state (static friction state) based on the static friction coefficient. The engagement control is preferably performed using the differential pressure ΔP as a value. In other words, by accurately learning the differential pressure ΔP when the lock-up clutch 26 transitions from the static friction state to the dynamic friction state, the engagement force of the lock-up clutch 26 can be increased as much as possible while the lock-up clutch 26 is in the engaged state. It is possible to know the pressure difference ΔP to be suppressed.

Preferably, the lock-up clutch control means 88 is engaged with a torque capacity T _C (target torque capacity T _C ^* ) as low as possible within the limit where the lock-up clutch 26 does not slip in the torque fuse control. When the lockup control command signal S _L for controlling the differential pressure ΔP that realizes the torque capacity T _C is output to the hydraulic control circuit 100, the learning control by the differential pressure learning control means 92 is performed. The result of is used. That is, the differential pressure ΔP is gradually reduced from the state in which the lockup clutch 26 is engaged, which is the result of the learning control by the differential pressure learning control means 92 stored in the storage device 94, and the lockup clutch 26 outputs a lockup control command signal S _L to the hydraulic control circuit 100 that realizes the differential pressure ΔP at the time of starting to slip. By doing in this way, when engaging the lockup clutch 26 in the torque fuse control, the fastening force can be suppressed as much as possible while maintaining the engaged state. In particular, in the vehicle 10 including the belt type continuously variable transmission 18 as in the present embodiment, the torque input to the external input torque while suppressing the belt clamping pressure in the continuously variable transmission 18 as much as possible in the torque fuse control. On the other hand, the lock-up clutch 26 can be slid sufficiently.

In addition, the differential pressure learning control unit 92 preferably gradually decreases the differential pressure ΔP from the state in which the lockup clutch 26 is engaged, and the lockup clutch 26 starts to slip with respect to the learning control. The first differential pressure ΔP ₁ (at the time indicated by (1) in FIG. 11) and the differential pressure ΔP are gradually increased from the released state of the lock-up clutch 26, and the lock-up clutch 26 is engaged. The second differential pressure ΔP _{2 at} the time indicated by (2) in FIG. 11 is compared. Further, preferably, as a result of the comparison, when said second better of the first differential pressure [Delta] P ₁ than the pressure difference [Delta] P ₂ is determined to be high, the second differential pressure [Delta] P ₂ The learning control is performed using as a learning value. In other words, the learning control is basically performed using the first differential pressure ΔP ₁ as a learning value, but it is determined that the second differential pressure ΔP ₂ is lower than the first differential pressure ΔP _1. If so, the learning control is performed using the second differential pressure ΔP ₂ as a learning value. By such control, it is possible to perform learning control with higher accuracy with respect to the differential pressure ΔP that determines the engagement state of the lockup clutch 26. Such learning control is executed corresponding to each steady running, or the result of the learning control is stored in the storage device 94 in association with each relation value, and new learning control is performed. As described above, it is updated every time.

  FIG. 12 is a flowchart for explaining a main part of the lockup clutch differential pressure learning control by the electronic control unit 50, and is repeatedly executed at a predetermined cycle.

First, in step (hereinafter, step is omitted) S1, it is determined whether or not the traveling state of the vehicle 10 is steady traveling, that is, whether or not the vehicle speed V and the accelerator opening degree A _CC are substantially constant. . If the determination at S1 is negative, the routine is terminated accordingly. If the determination at S1 is affirmative, the difference from the engaged state of the lockup clutch 26 is determined at S2. A lockup control command signal S _L is output so as to gradually decrease the pressure ΔP. Next, in S3, the slip-out of the lockup clutch 26 is determined based on the difference between the engine rotational speed _NE and the turbine rotational speed _NT . For example, the difference between these engine rotational speed N _E and the turbine rotational speed N _T is the determination at S3 at the time of equal to or greater than a predetermined threshold is performed. Next, in S4, the lock-up control instruction signal (differential pressure command value) corresponding to the differential pressure ΔP at the time the transition time i.e. the lock-up clutch 26 is started to slip from static friction state to a dynamic friction state P _A ^* is obtained The

Next, in S5, a lockup control command signal _SL is outputted so as to gradually increase the differential pressure ΔP from the state in which the lockup clutch 26 is released. Next, in S6, the engagement of the lockup clutch 26 is determined based on the difference between the engine rotational speed _NE and the turbine rotational speed _NT . For example, the difference between these engine rotational speed N _E and the turbine rotational speed N _T is determined in S6 when it becomes less than the predetermined threshold value is performed. Next, in S7, a lockup control command signal (differential pressure command value) P _B ^* corresponding to the differential pressure ΔP at the time of transition from the dynamic friction state to the static friction state, that is, when the lockup clutch 26 is engaged is acquired. The Next, in S8, the lockup control command signal P _A ^* acquired in S4 and the lockup control command signal P _B ^* acquired in S7 are compared, and P _A ^* <P _B ^* . It is confirmed whether or not. Next, in S9, based on the comparison result in S8, when P _A ^* <P _B ^* , P _A ^* is used as a learning value, and when P _A ^* > P _B ^* , P _B ^* is set. The learning control of the differential pressure ΔP is performed as a learning value, and the result of the learning control is associated with each relation value and stored (updated) in the storage device 94, and then this routine is terminated. In the above control, S1 corresponds to the operation of the steady running determination means 90, and S2 to S9 correspond to the operation of the differential pressure learning control means 92, respectively.

  Thus, according to the present embodiment, during steady running, the differential pressure ΔP is gradually decreased from the state in which the lock-up clutch 26 is engaged, and the differential pressure ΔP at the time when the lock-up clutch 26 starts to slip. Therefore, the differential pressure ΔP at the time of transition from the static friction state to the dynamic friction state of the lockup clutch 26 can be learned with high accuracy, and the limit lockup clutch capacity in the static friction state is preferable. Can be determined. That is, it is possible to provide an electronic control device 50 for a vehicle lock-up clutch that performs highly accurate learning control regarding the differential pressure ΔP that defines the engaged state.

Further, regarding the learning control, the differential pressure ΔP is gradually decreased from the state in which the lock-up clutch 26 is engaged, and the first differential pressure ΔP ₁ when the lock-up clutch 26 starts to slip and the lock-up clutch 26 Since the differential pressure ΔP is gradually increased from the released state of the clutch 26 and compared with the second differential pressure ΔP ₂ when the lock-up clutch 26 is engaged, More accurate learning control can be performed with respect to the differential pressure ΔP that determines the engagement state.

Further, as a result of said comparison, when said second better of the first differential pressure [Delta] P ₁ than the pressure difference [Delta] P ₂ is determined to be high, the second differential pressure [Delta] P ₂ as the learned value Since the learning control is performed, more accurate learning control can be performed with respect to the differential pressure ΔP that determines the engagement state of the lockup clutch 26.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and may be implemented in other modes.

  For example, in the above-described embodiment, the result of the learning control of the differential pressure ΔP of the lockup clutch 26 by the differential pressure learning control unit 92 is that the lock is applied to the sudden input torque such as overstepping on a rough road. Although it is used for so-called torque fuse control in which the engagement pressure is controlled so that the up clutch 26 is slid, the present invention is not limited to this, and the engagement state of the lock up clutch (lock The results of the learning control can be widely used in connection with various controls that are required to suppress the fastening force as much as possible while maintaining the up state.

  In the above-described embodiment, the belt includes the driving pulley 42 and the driven pulley 46 whose effective diameters are variable, and the transmission belt 48 wound between the driving pulley 42 and the driven pulley 46. Although the example in which the present invention is applied to a vehicle having a continuously variable transmission 18 has been described, for example, a plurality of engagement devices are provided, and a plurality of shift steps are achieved by a combination of engagement and release of these engagement devices. The present invention is also suitably applied to a vehicle equipped with a multistage automatic transmission that is selectively established or a toroidal-type continuously variable transmission. That is, the present invention is widely applied to a vehicle including a torque converter provided between an engine and a transmission, and a lockup clutch that directly connects an input rotating member and an output rotating member in the torque converter by engagement. Applicable.

  In addition, although not illustrated one by one, the present invention is implemented with various modifications within a range not departing from the gist thereof.

  10: vehicle, 12: engine, 14: torque converter, 14p: pump impeller (input rotating member), 14s: stator impeller (output rotating member), 18: continuously variable transmission, 26: lockup clutch, 50: Electronic control unit

Claims (3)

In a vehicle provided with a torque converter provided between an engine and a transmission, and a lockup clutch that directly connects an input rotary member and an output rotary member of the torque converter by engagement, the engagement of the lockup clutch A control device for a vehicle lock-up clutch that learns a differential pressure that determines a combined state,
A vehicle characterized by gradually reducing the differential pressure from a state in which the lock-up clutch is engaged during steady running and performing learning control related to the differential pressure at the time when the lock-up clutch starts to slip. Lockup clutch control device. Regarding the learning control,
Gradually reducing the differential pressure from a state in which the lock-up clutch is engaged, and a first differential pressure at the time when the lock-up clutch starts to slide;
2. The vehicle lockup according to claim 1, wherein the differential pressure is gradually increased from a state in which the lockup clutch is released, and is compared with a second differential pressure at the time when the lockup clutch is engaged. Control device for clutch.   As a result of the comparison, when it is determined that the first differential pressure is higher than the second differential pressure, the learning control is performed using the second differential pressure as a learning value. The vehicle lockup clutch control device according to claim 2.

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