JP5765188B2 - Control device for continuously variable transmission for vehicle - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission for a vehicle in which shift control is executed such that an actual gear ratio becomes a target gear ratio.

  A continuously variable transmission such as a belt type continuously variable transmission or a toroidal type continuously variable transmission is well known. For example, it is a continuously variable transmission described in Patent Documents 1-3. In such a continuously variable transmission, shift control is executed so that a target speed ratio of the continuously variable transmission set based on the vehicle state such as the vehicle speed and the accelerator opening is realized. At this time, feedback control (FB control) based on the deviation between the actual transmission ratio (actual transmission ratio) of the continuously variable transmission calculated from the input rotational speed and the output rotational speed of the continuously variable transmission and the target transmission ratio. The accuracy of the shift control is improved. Here, for example, in order to reduce the cost, it has been proposed to reduce the rotational speed sensor for detecting the rotational speed. In Patent Document 1, the input rotational speed sensor that detects the input rotational speed of the continuously variable transmission is reduced, and the rotational speed of the turbine shaft of the torque converter that is mechanically connected to the input shaft of the continuously variable transmission is detected. It is disclosed that the actual gear ratio at the time of the FB control is calculated by using the detected value of the turbine rotational speed sensor for the purpose as the input rotational speed.

JP 2005-164002 A JP 2007-255633 A JP 2004-211838 A

  By the way, when the input rotational speed sensor is reduced as described above and the turbine rotational speed sensor has the function of the input rotational speed sensor, if the turbine rotational speed sensor fails, the input rotational speed of the continuously variable transmission is reduced. It cannot be detected. Therefore, when the turbine rotational speed sensor fails, the actual speed ratio cannot be calculated, and the speed change control of the continuously variable transmission by the FB control cannot be executed. In such a case, it can be considered that the shift control of the continuously variable transmission is executed only by feedforward control (FF control) as fail-safe. For example, it is conceivable to perform shift control by FF control that outputs a hydraulic command value fixed at a constant value. However, in the case of such shift control by FF control, the speed ratio of the continuously variable transmission is determined according to a certain value, and there is a possibility that traveling performance in a wide vehicle speed range cannot be ensured. The above-mentioned problems are not known, and it is still not possible to achieve both ensuring acceleration performance when starting the vehicle and ensuring traveling performance at a relatively high vehicle speed when the actual gear ratio cannot be calculated. Not proposed.

  The present invention has been made against the background of the above circumstances, and its purpose is to travel in a wide vehicle speed range even when the actual transmission ratio of the continuously variable transmission cannot be detected. An object of the present invention is to provide a control device for a continuously variable transmission for a vehicle capable of ensuring performance.

The gist of the first invention for achieving the above object is that: (a) in a continuously variable transmission for a vehicle to which power of a driving force source is transmitted via a torque converter, an actual gear ratio is a target gear shift. A control device for a continuously variable transmission for a vehicle in which a shift control is executed so as to achieve a ratio, and (b) a value based on a detected value of a turbine rotational speed of the torque converter is set to a value of the continuously variable transmission for the vehicle (C) When the turbine rotational speed cannot be detected, a plurality of types of targets that change in a step set in advance in association with the vehicle speed are used. The step-shifting control is executed by switching the gear ratio based on the vehicle speed.

In this way, when the turbine rotational speed cannot be detected, stepped speed change control is performed by switching a plurality of types of target speed ratios that change stepwise in advance in association with the vehicle speed based on the vehicle speed. As a result, the acceleration performance by the gear ratio suitable for starting the vehicle and the traveling performance by the gear ratio suitable for a relatively high vehicle speed can both be achieved. In other words, when the turbine rotation speed sensor fails, the limp home performance (for example, provisional travel performance, emergency travel performance, evacuation travel performance) is appropriately achieved by balancing the acceleration performance at the start of the vehicle with the travel performance at a relatively high vehicle speed. Can be secured. Therefore, even when the actual transmission ratio of the continuously variable transmission cannot be detected, it is possible to ensure traveling performance in a wide vehicle speed range.
The gist of the second invention for achieving the above object is that: (a) In a continuously variable transmission for a vehicle in which the power of a driving force source is transmitted via a torque converter, the actual gear ratio is a target gear shift. A control device for a continuously variable transmission for a vehicle in which a shift control is executed so as to achieve a ratio, and (b) a value based on a detected value of a turbine rotational speed of the torque converter is set to a value of the continuously variable transmission for the vehicle (C) When the output shaft rotational speed of the continuously variable transmission for the vehicle cannot be detected, the value based on the detected value of the wheel rotational speed is used. Is used as the vehicle speed, and stepwise shift control is executed by switching a plurality of types of target speed ratios that change stepwise in advance in association with the vehicle speed based on the vehicle speed.
In this way, when the output shaft rotation speed cannot be detected, stepwise shift control is performed by switching a plurality of types of target gear ratios that change stepwise in advance in association with the vehicle speed based on the vehicle speed. Therefore, it is possible to achieve both of ensuring acceleration performance with a gear ratio suitable for starting the vehicle and ensuring traveling performance with a gear ratio suitable for a relatively high vehicle speed. In other words, when the output shaft rotation speed sensor fails, the acceleration performance at the time of starting the vehicle and the running performance at a relatively high vehicle speed can be made compatible to ensure the limp home performance appropriately. Therefore, even when the actual transmission ratio of the continuously variable transmission cannot be detected, it is possible to ensure traveling performance in a wide vehicle speed range.
Thus, the first invention and the second invention can eliminate the input shaft rotation speed sensor, and can reduce the cost. Further, the turbine rotational speed sensor malfunctions for a vehicle that eliminates the input rotational speed sensor and executes shift control of the continuously variable transmission for the vehicle with a value based on the detected value of the turbine rotational speed different from the input shaft rotational speed. Sometimes this is a particularly useful invention for the lack of an alternative rotational speed sensor.

Here, a third invention is the control device for a continuously variable transmission for a vehicle according to the first invention or the second invention , wherein the plurality of types of target gear ratios are set in a preset low vehicle speed range. A target gear ratio on the minimum vehicle speed side for controlling the actual gear ratio to a gear ratio on the minimum vehicle speed side or a gear ratio in the vicinity of the minimum vehicle speed side, and a preset high speed on the higher vehicle speed side than the low vehicle speed range. In the vehicle speed range, the actual gear ratio includes the target gear ratio on the highest vehicle speed side for controlling the actual gear ratio to the gear ratio on the highest vehicle speed side or the gear ratio in the vicinity of the highest vehicle speed side. In this way, when the actual transmission ratio of the continuously variable transmission cannot be detected, the target transmission ratio is switched to the target transmission ratio on the lowest vehicle speed side suitable for starting the vehicle at least in the low vehicle speed range, and the high vehicle speed is set. The target gear ratio on the maximum vehicle speed side suitable for a relatively high vehicle speed in the region is switched. Accordingly, it is possible to appropriately achieve both ensuring acceleration performance when starting the vehicle and ensuring traveling performance at a relatively high vehicle speed.

According to a fourth aspect of the present invention, in the control device for a continuously variable transmission for a vehicle according to any one of the first to third aspects of the present invention , an adjacent target among the plurality of types of target speed ratios. Between the gear ratios, a predetermined hysteresis is provided between the downshift switching vehicle speed to the target gear ratio on the low vehicle speed side and the upshift switching vehicle speed to the target gear ratio on the high vehicle speed side. In this way, the switching of the target gear ratio between the adjacent target gear ratios is prevented from being repeated in a short period of time, thereby avoiding shift hunting when stepped shift control is executed. The

According to a fifth aspect , in the control device for a continuously variable transmission for a vehicle according to the fourth aspect, the actual speed ratio is controlled to a speed ratio on the minimum vehicle speed side or a speed ratio in the vicinity of the minimum vehicle speed side. The vehicle speed for downshifting to the target speed ratio on the minimum vehicle speed side is set in advance so that the actual speed ratio becomes the speed ratio on the minimum vehicle speed side or the speed ratio in the vicinity of the minimum vehicle speed before the vehicle stops. The upshift switching vehicle speed to the target speed ratio on the lower vehicle speed side and the target speed ratio on the higher vehicle speed side adjacent to the target speed ratio on the lowest vehicle speed side is within the vehicle speed range in which the vehicle can travel at the target speed ratio on the lowest vehicle speed side. This is a threshold preset as the upper limit vehicle speed. In this way, the acceleration performance when the vehicle restarts is ensured appropriately. Moreover, the acceleration performance after the vehicle starts is maintained appropriately. In addition, traveling performance at a relatively high vehicle speed is appropriately ensured.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the schematic structure of the vehicle to which this invention is applied, and is a block diagram explaining the principal part of the control system provided in the vehicle. It is a hydraulic circuit diagram which shows the principal part regarding the shift control etc. of a continuously variable transmission among hydraulic control circuits. It is a functional block diagram explaining the principal part of the control function of an electronic controller. It is a figure which shows an example of the shift map used when calculating | requiring a target input shaft rotational speed in the transmission control of a continuously variable transmission. It is a figure which shows an example of the belt clamping pressure map used when calculating | requiring a target secondary pressure in the transmission control of a continuously variable transmission. FIG. 5 is a diagram showing an example of a failure time shift map corresponding to a failure time target gear ratio, and corresponds to the normal time shift map of FIG. 4. FIG. 5 is a flowchart for explaining a control operation for ensuring a traveling performance in a wide vehicle speed range even when a main part of the control operation of the electronic control unit, that is, when the actual transmission ratio of the continuously variable transmission cannot be detected. FIG. FIG. 7 is a diagram illustrating an example of a failure shift map corresponding to a three-stage failure target transmission gear ratio, which is an embodiment different from FIG. 6.

  In the present invention, preferably, the power of the driving force source is transmitted to the driving wheels via the vehicle continuously variable transmission. As the driving power source, 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 other prime movers such as an electric motor may be used alone or in combination with the engine. You can also.

  Preferably, in the continuously variable transmission for a vehicle, for example, a transmission belt is wound around a pair of variable pulleys (an input-side variable pulley and an output-side variable pulley), and a gear ratio is continuously changed steplessly. A so-called belt-type continuously variable transmission, a pair of cone members that rotate around a common axis and a plurality of rollers that can rotate around the axis are sandwiched between the pair of cone members. It is constituted by a so-called toroidal continuously variable transmission or the like in which the gear ratio is continuously changed by changing the intersection angle between the rotation center of the roller and the shaft center.

  Preferably, a hydraulic pressure control circuit is configured so that the hydraulic pressure applied to the input-side variable pulley and the output-side variable pulley is controlled independently of each other. By such an oil pressure control circuit, the input-side thrust in the input-side variable pulley and the output-side thrust in the output-side variable pulley are respectively controlled, thereby realizing a target shift while preventing the transmission belt from slipping. Thus, the shift control is executed. Alternatively, the hydraulic pressure applied to the input side variable pulley does not directly control the hydraulic pressure, but by controlling the flow rate of the hydraulic oil to the hydraulic cylinder of the input side variable pulley, as a result, The hydraulic control circuit may be configured to generate a hydraulic pressure that acts on the variable pulley.

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

  FIG. 1 is a diagram illustrating a schematic configuration of a vehicle 10 to which the present invention is applied, and is a block diagram illustrating a main part of a control system provided for controlling each part of the vehicle 10. In FIG. 1, in a vehicle 10, power output from an engine 12 as a driving power source for traveling is a torque converter 14 as a fluid transmission device, a forward / reverse switching device 16, and a belt as a continuously variable transmission for a vehicle. It is transmitted to the left and right drive wheels 24 via a stepless continuously variable transmission (hereinafter referred to as continuously variable transmission (CVT)) 18, a reduction gear device 20, a 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 impeller 14t connected to the forward / reverse switching device 16 via a turbine shaft 30 corresponding to an output side member of the torque converter 14. The power is transmitted through the fluid. A lockup clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t. The pump impeller 14p controls transmission of the continuously variable transmission 18, generates belt clamping pressure in the continuously variable transmission 18, switches the power transmission path in the forward / reverse switching device 16, and transmits power to the vehicle 10. A mechanical oil pump 28 is connected which is generated by rotationally driving hydraulic pressure for supplying lubricating oil to each part of the path by the engine 12.

  The forward / reverse switching device 16 is mainly configured by a forward clutch C1, a reverse brake B1, and a double pinion planetary gear device 16p. The turbine shaft 30 is integrally connected to the sun gear 16s of the planetary gear device 16p, and the input shaft 32 of the continuously variable transmission 18 is integrally connected to the carrier 16c of the planetary gear device 16p. The carrier 16c and the sun gear 16s are selectively connected via the forward clutch C1, and the ring gear 16r of the planetary gear unit 16p is selectively fixed to the housing 34 as a non-rotating member via the reverse brake B1. The The forward clutch C1 and the reverse brake B1 are hydraulic friction engagement devices.

  In the forward / reverse switching device 16 configured as described above, when the forward clutch C1 is engaged and the reverse brake B1 is released, the forward / reverse switching device 16 is brought into an integral rotation state, thereby causing the turbine shaft 30 to rotate. Is directly connected to the input shaft 32, and a forward power transmission path is established (achieved) (that is, a power transmission enabling state for enabling forward power transmission is established). 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 (that is, allows reverse power transmission). The input shaft 32 is rotated in the opposite direction with respect to the turbine shaft 30. When both the forward clutch C1 and the reverse brake B1 are released, the forward / reverse switching device 16 is in a neutral state (power transmission cut-off state) in which power transmission is cut off.

  The continuously variable transmission 18 is an input-side variable pulley (primary pulley, primary sheave) 40 having a variable effective diameter that is an input-side member provided on the input shaft 32 and an output-side member that is provided on the output shaft 42. A pair of variable pulleys 40, 44 having an output-side variable pulley (secondary pulley, secondary sheave) 44 having a variable diameter, and a transmission belt 46 wound between the pair of variable pulleys 40, 44 are provided. The power is transmitted through a frictional force between the pair of variable pulleys 40 and 44 and the transmission belt 46.

  The primary pulley 40 is provided with a fixed rotating body (fixed sheave) 40 a as an input side fixed rotating body fixed to the input shaft 32, and is not rotatable relative to the input shaft 32 and is movable in the axial direction. A movable rotating body (movable sheave) 40b as the input side movable rotating body and an input side thrust (primary thrust) Win (= primary pressure Pin × pressure receiving area) in the primary pulley 40 for changing the V groove width between them. ) Is provided as an input side hydraulic cylinder (primary side hydraulic cylinder) 40c. The secondary pulley 44 is fixed to the output shaft 42 and is a fixed rotating body (fixed sheave) 44a as an output-side fixed rotating body. The secondary pulley 44 is not rotatable relative to the output shaft 42 and is movable in the axial direction. A movable rotating body (movable sheave) 44b as an output-side movable rotating body provided, and an output-side thrust (secondary thrust) Wout (= secondary pressure Pout ×) in the secondary pulley 44 for changing the V groove width between them. And an output side hydraulic cylinder (secondary side hydraulic cylinder) 44c as a hydraulic actuator for providing a pressure receiving area).

The primary pressure Pin, which is the hydraulic pressure to the primary hydraulic cylinder 40c, and the secondary pressure Pout, which is the hydraulic pressure to the secondary hydraulic cylinder 44c, are independently regulated by the hydraulic control circuit 100 (see FIG. 2). The primary thrust Win and the secondary thrust Wout are directly or indirectly controlled. As a result, the V-groove width of the pair of variable pulleys 40 and 44 is changed to change the engagement diameter (effective diameter) of the transmission belt 46, and the transmission gear ratio (gear ratio) γ (= input shaft rotational speed N _IN / output shaft). The rotational speed N _OUT ) is continuously changed, and the frictional force (belt clamping pressure) between the pair of variable pulleys 40 and 44 and the transmission belt 46 is controlled so that the transmission belt 46 does not slip. . In this way, by controlling the primary thrust Win and the secondary thrust Wout, the actual transmission ratio (actual transmission ratio) γ is set to the target transmission ratio γ ^* while preventing the transmission belt 46 from slipping. The input shaft rotational speed N _IN is the rotational speed of the input shaft 32 and is the rotational speed on the input side of the continuously variable transmission 18. The output shaft rotational speed N _OUT is the rotational speed of the output shaft 42 and the rotational speed on the output side of the continuously variable transmission 18. In this embodiment, as can be seen from FIG. 1, the input shaft rotation speed N _IN is the same as the rotation speed of the primary pulley 40, and the output shaft rotation speed N _OUT is the same as the rotation speed of the secondary pulley 44.

In the continuously variable transmission 18, for example, when the primary pressure Pin is increased, the V groove width of the primary pulley 40 is narrowed to reduce the speed ratio γ, that is, the continuously variable transmission 18 is upshifted. Further, when the primary pressure Pin is lowered, the V groove width of the primary pulley 40 is widened to increase the gear ratio γ, that is, the continuously variable transmission 18 is downshifted. Therefore, when the V groove width of the primary pulley 40 is minimized, the minimum speed ratio γmin (the speed ratio on the highest vehicle speed side, the highest Hi) is formed as the speed ratio γ of the continuously variable transmission 18. Further, when the V-groove width of the primary pulley 40 is maximized, the maximum speed ratio γmax (the speed ratio on the lowest vehicle speed side, the lowest) is formed as the speed ratio γ of the continuously variable transmission 18. The primary pressure Pin (primary thrust Win also agrees) and the secondary pressure Pout (secondary thrust Wout agrees) are prevented from slipping (belt slipping) of the transmission belt 46, and the primary thrust Win and the secondary thrust Wout Therefore, the target speed ratio γ ^* is realized, and the target speed change is not realized only by one pulley pressure (the thrust is also agreed).

  Further, the vehicle 10 is provided with an electronic control unit 50 including, for example, a control unit for the continuously variable transmission 18. The electronic control unit 50 includes, for example, a so-called microcomputer having a CPU, a RAM, a ROM, an input / output interface, and the like. The CPU uses a temporary storage function of the RAM and follows a program stored in the ROM in advance. Various controls of the vehicle 10 are executed by performing signal processing. For example, the electronic control unit 50 is configured to execute output control of the engine 12, shift control of the continuously variable transmission 18, belt clamping pressure control, and the like, and for engine control, the continuously variable transmission 18 as necessary. It is configured separately for hydraulic control.

The electronic control unit 50 includes sensors provided in the vehicle 10 (for example, an engine speed sensor 52, a turbine speed sensor 54, an output shaft speed sensor 56, a wheel speed sensor 58, an accelerator opening sensor 60, a vehicle acceleration sensor). 62, the secondary pressure sensor 64, the battery sensor 66, etc.) are output as output rotational speeds of the continuously variable transmission 18 corresponding to various input signals (for example, engine rotational speed N _E , turbine rotational speed N _T , and vehicle speed V). The output shaft rotation speed N _OUT which is the rotation speed of the shaft 42, the wheel rotation speed N _W which is the rotation speed of the driving wheel 24 and the driven wheel, the accelerator opening Acc, and the vehicle acceleration (vehicle reduction) which is the acceleration in the longitudinal direction of the vehicle 10. Speed also agrees) G, secondary pressure Pout, battery temperature TH _BAT , battery charge / discharge current I _BAT and battery voltage V _BAT Etc.) are supplied. Further, the electronic control device 50 outputs various output signals (for example, an engine output control command signal S _{E for} controlling the output of the engine 12) to each device (for example, the engine 12, the hydraulic control circuit 100, etc.) provided in the vehicle 10. A hydraulic control command signal S _CVT for hydraulic control related to the shift of the continuously variable transmission 18 is supplied. Further, the electronic control unit 50 sequentially calculates the state of charge (charge capacity) SOC of the battery (power storage device) based on, for example, the battery temperature TH _BAT , the battery charge / discharge current I _BAT , and the battery voltage V _BAT . The hydraulic control command signal S _CVT includes, for example, a command signal for driving the linear solenoid valve SLP for controlling the primary pressure Pin, a command signal for driving the linear solenoid valve SLS for controlling the secondary pressure Pout, and a line command signal for driving a linear solenoid valve SLT for controlling the hydraulic pressure P _L, and the like.

FIG. 2 is a hydraulic circuit diagram showing a main part of the hydraulic control circuit 100 related to the shift control of the continuously variable transmission 18. 2, the hydraulic control circuit 100 includes, for example, an oil pump 28, a primary pressure control valve 110 that regulates the primary pressure Pin supplied to the primary hydraulic cylinder 40c in order to change the speed ratio γ of the continuously variable transmission 18. secondary pressure control valve 112 for pressurizing the secondary pressure Pout supplied to the secondary side hydraulic cylinder 44c in order to prevent belt slippage regulating the primary regulator valve 114 which applies the line pressure P _L tone modulator valve for pressurizing regulates the modulator pressure P _M 116, the linear solenoid valve SLP for controlling the primary pressure Pin, the linear solenoid valve SLS which controls the secondary pressure Pout, the linear solenoid valve SLT for controlling the line pressure P _L, Se as a hydraulic pressure sensor for detecting the secondary pressure Pout Secondary and a pressure sensor 64 and the like.

The line oil pressure P _L corresponds to the engine load or the like based on the control oil pressure P _SLT which is the output oil pressure of the linear solenoid valve SLT by the relief type primary regulator valve 114 with the working oil pressure output from the oil pump 28 as the original pressure. Regulated to the value. For example, the line pressure P _L is pressure regulated on the basis of the control hydraulic pressure P _SLT of hydraulic pressure by adding a predetermined margin to the hydraulic pressure of higher primary pressure Pin and the secondary pressure Pout (margin) is set so as to give The Therefore, the is avoided that the line pressure P _L as the original pressure in pressure regulating operation of the primary pressure control valve 110 and the secondary pressure control valve 112 is insufficient, the line pressure P _L from being unnecessarily high It is possible. Moreover, modulator pressure _{P M,} the control hydraulic pressure _{P SLT} is controlled by the electronic control unit 50, the linear solenoid valve SLP output hydraulic and is controlled oil pressure _{P SLP,} and the control oil pressure _{P SLS} is the output oil pressure of the linear solenoid valve SLS be comprised between each source pressure and pressure is adjusted to a constant pressure by a modulator valve 116 to line pressure P _L as source pressure.

Primary pressure control valve 110, the spool valve to allow the supply line pressure P _L by opening and closing an input port 110i by being movable in the axial direction from the input port 110i to the primary hydraulic cylinder 40c through the output port 110t 110b, a spring 110b as an urging means for urging the spool valve element 110a in the valve opening direction, and a control hydraulic pressure for accommodating the spring 110b and applying thrust in the valve opening direction to the spool valve element 110a an oil chamber 110c that accepts P _SLP, a feedback oil chamber 110d that accepts line pressure _{P L} which is output from the output port 110t to apply thrust in the valve closing direction to the spool valve element 110a, closing the spool valve element 110a accept the modulator pressure P _M in order to impart a thrust in the direction Oil chamber 110e. The primary pressure control valve 110 configured as described above, for example, supplies the control oil pressure P _SLP by the line pressure P _L as a pilot pressure regulating control to control the to the primary hydraulic cylinder 40c. Thus, the line pressure P _L is supplied to the primary hydraulic cylinder 40c as the primary pressure Pin. For example, when the control oil pressure P _SLP increases, the primary pressure Pin increases due to the spool valve element 110a moving upward in FIG. On the other hand, for example, when the control oil pressure P _SLP decreases, the primary pressure Pin decreases due to the spool valve element 110a moving downward in FIG.

Secondary pressure control valve 112, the spool valve to be supplied through the output port 112t to open and close an input port 112i to the line pressure P _L from the input port 112i by being movable in the axial direction to the secondary side hydraulic cylinder 44c A child 112a, a spring 112b as an urging means for urging the spool valve element 112a in the valve opening direction, and a control hydraulic pressure for accommodating the spring 112b and applying a thrust in the valve opening direction to the spool valve element 112a an oil chamber 112c that accepts P _SLS, and a feedback oil chamber 112d that accepts line pressure _{P L} which is output from the output port 112t to apply thrust in the valve closing direction to the spool valve element 112a, closing the spool valve element 112a accept the modulator pressure P _M in order to impart a thrust in the direction Oil chamber 112e. The secondary pressure control valve 112 configured as described above, for example, supplies the control oil pressure P _SLS and the line pressure P _L as a pilot pressure regulating control to control the to the secondary side hydraulic cylinder 44c. Thus, the line pressure P _L is supplied to the secondary-side hydraulic cylinder 44c as the secondary pressure Pout. For example, when the control oil pressure P _SLS increases, the secondary pressure Pout increases as the spool valve element 112a moves upward in FIG. On the other hand, for example, when the control oil pressure P _SLS decreases, the secondary pressure Pout decreases due to the spool valve element 112a moving downward in FIG.

FIG. 3 is a functional block diagram for explaining the main part of the control function by the electronic control unit 50. 3, the engine output control means or the engine output control unit 70, the throttle signal and the injection signal and an ignition timing signal, respectively the throttle actuator and the fuel injection system of the engine output control command signal S _E, such as for the output control of the engine 12 And output to the ignition device. For example, the engine output control unit 70 sets a target engine torque T _E ^* for obtaining a driving force (driving torque) corresponding to the accelerator opening Acc, and throttles the target engine torque T _E ^* so as to obtain the target engine torque T _E ^*. In addition to opening and closing the electronic throttle valve with an actuator, the fuel injection amount is controlled with a fuel injection device, and the ignition timing is controlled with an ignition device.

The continuously variable transmission control means, that is, the continuously variable transmission control unit 72, for example, performs primary pressure so as to achieve the target gear ratio γ ^* of the continuously variable transmission 18 while preventing belt slippage of the continuously variable transmission 18. A primary command oil pressure Pintgt as a command value (or target primary pressure Pin ^* ) of Pin and a secondary command oil pressure Pouttgt as a command value (or target secondary pressure Pout ^* ) of a secondary pressure Pout are determined, and the primary command oil pressure Pintgt and secondary and it outputs the command oil Pouttgt to the hydraulic control circuit 100 as the hydraulic pressure control command signal _{S CVT.}

Specifically, the continuously variable transmission control unit 72 uses the accelerator opening Acc as shown in FIG. 4 as a parameter, for example, the vehicle speed V (output shaft rotational speed N _OUT ) and the target input shaft rotational speed of the continuously variable transmission 18. setting a target input shaft rotational speed N _iN ^* based on previously obtained by the vehicle state indicated by the actual vehicle speed V and the accelerator opening Acc from the stored relationship (shift map) between N _iN ^*. The continuously variable transmission control unit 72 calculates a target speed ratio γ ^* (= N _IN ^* / N _OUT ) based on the target input shaft rotational speed N _IN ^* . The shift map in FIG. 4 corresponds to shift conditions for achieving both drivability (power performance) and fuel efficiency (fuel efficiency), for example, and the larger the vehicle speed V and the greater the accelerator opening Acc, the greater the gear ratio. A target input shaft rotational speed N _IN ^{* that} is γ is set. Further, the target speed ratio γ ^* (= N _IN ^* / N _OUT ) is determined within the range between the minimum speed ratio γmin and the maximum speed ratio γmax of the continuously variable transmission 18.

The continuously variable transmission control unit 72 uses the input torque T _IN (or the accelerator opening Acc or the like) of the continuously variable transmission 18 as shown in FIG. from Pout ^* previously obtained with the stored relationship between the (belt clamping pressure map), the actual gear ratio gamma (actual speed ratio gamma) and on the basis of the vehicle condition represented by the input torque T _iN target secondary pressure Pout ^* Set. The belt clamping pressure map in FIG. 5 corresponds to the control conditions for causing the pair of variable pulleys 40 and 44 to generate a belt clamping pressure that does not cause belt slip and does not increase unnecessarily, for example.

The continuously variable transmission control unit 72 uses, for example, a continuously variable transmission as a torque (= T _E × t) obtained by multiplying the engine torque T _E by the torque ratio t of the torque converter 14 (= turbine torque T _T / pump torque T _P ). It calculates an input torque _{T iN} of the machine 18. Further, the CVT control unit 72, for example, the amount of intake air (or the throttle valve opening, etc.) not shown which is stored in advance experimentally sought between the engine speed N _E and engine torque T _E as a parameter from relationship (engine torque map) to calculate the estimated value of the engine torque T _E on the basis of the actual intake air amount and the engine rotational speed N _E. Further, the continuously variable transmission control unit 72 determines, for example, the previously determined experimentally stored speed ratio e (= turbine rotational speed N _T / pump rotational speed N _P ) of the torque converter 14 and the torque ratio t. The torque ratio t is calculated based on the actual speed ratio e from the illustrated relationship (torque converter operating characteristic diagram).

The vehicle 10 of this embodiment does not include an input shaft rotation speed sensor for detecting the input shaft rotation speed N _IN of the continuously variable transmission 18. Therefore, the continuously variable transmission control unit 72 corresponds to the input shaft rotational speed N _IN when executing the shift control of the continuously variable transmission 18 and is different from the input shaft rotational speed N _IN. The actual speed ratio γ (= N _IN / N _OUT ) is calculated by using, for example, a value based on the detected value of the turbine rotational speed _NT as the input shaft rotational speed N _IN . For example, during forward travel in which the forward clutch C1 is engaged, the turbine rotational speed _NT is used as it is as the input shaft rotational speed N _IN .

The continuously variable transmission control unit 72 calculates a target secondary thrust Wout ^* (= pressure receiving area of Pout ^* × 44b) based on the target secondary pressure Pout ^* . CVT control unit 72, the thrust ratio for realizing the target speed ratio gamma ^* and the target speed ratio ^{γ * τ (= Wout / Win} ) previously obtained with stored relationship (not shown) of the (thrust ratio From the map), the thrust ratio τ is calculated based on the target gear ratio γ ^* . The continuously variable transmission control unit 72 calculates a target primary thrust Win ^* (= Wout ^* / τ) based on the calculated thrust ratio τ and the target secondary thrust Wout ^* . The continuously variable transmission control unit 72 calculates the target primary pressure Pin ^* (= the pressure receiving area of Win ^* / 40b) based on the target primary thrust Win ^* .

The continuously variable transmission control unit 72 determines a primary command oil pressure Pintgt from which a target primary pressure Pin ^* can be obtained and a secondary command oil pressure Pouttgt from which a target secondary pressure Pout ^* can be obtained by, for example, feedforward control (FF control). and outputs to the hydraulic control circuit 100 the Pintgt and secondary command oil Pouttgt as hydraulic control command signal _{S CVT.} The hydraulic control circuit 100, the following hydraulic pressure control command signal S _CVT, with pressure regulating the primary pressure Pin by operating the linear solenoid valve SLP, actuates the linear solenoid valve SLS pressure regulating the secondary pressure Pout by.

The continuously variable transmission control unit 72, for example, compensates for the oil pressure variation (variation in hydraulic control) on the primary pulley 40 side so that the actual gear ratio γ matches the target gear ratio γ ^*. The primary command oil pressure Pintgt is corrected by feedback control (FB control) based on a gear ratio deviation Δγ (= γ ^* −γ) between the ratio γ ^* and the actual gear ratio γ. Further, the continuously variable transmission control unit 72 is configured so that the secondary pressure Pout detected by the secondary pressure sensor 64 matches the target secondary pressure Pout ^* so as to compensate for the hydraulic pressure variation on the secondary pulley 44 side, for example. The secondary command oil pressure Pouttgt is corrected by FB control based on the hydraulic pressure difference ΔPout (= Pout ^* −Pout detection value) between the detected value of the pressure Pout and the target secondary pressure Pout ^* .

Incidentally, when reducing the input shaft rotational speed sensor for detecting an input shaft rotational speed N _IN as in this embodiment, to constitute a function of the input shaft rotational speed sensor as combine the turbine rotational speed sensor 54, If the turbine rotational speed sensor 54 fails, the turbine rotational speed _NT cannot be detected, and as a result, the input shaft rotational speed N _IN cannot be detected. For this reason, when the turbine rotation speed sensor 54 fails, the actual speed ratio γ cannot be calculated (detected). Alternatively, since the output shaft rotational speed N _OUT cannot be detected if the output shaft rotational speed sensor 56 fails, the actual speed ratio γ can be calculated (detected) in the same manner as when the turbine rotational speed sensor 54 fails. Can not. Thus, if the actual gear ratio γ cannot be calculated, the shift control of the continuously variable transmission 18 by the FB control cannot be executed. The fact that the actual speed ratio γ cannot be calculated means that the actual speed ratio γ cannot be calculated, but the actual speed ratio γ can be calculated but the actual speed ratio γ can be calculated. This includes cases where it is determined that the calculation accuracy is not obtained (in other words, the calculation accuracy of the actual gear ratio γ cannot be used for the shift control).

In such a case, as a fail safe, it is conceivable to execute the shift control of the continuously variable transmission 18 only by the FF control instead of the shift control of the continuously variable transmission 18 by the FF control and the FB control. However, when the turbine rotational speed _NT cannot be detected, the speed ratio e of the torque converter 14 cannot be calculated, so that the input torque T _IN of the continuously variable transmission 18 cannot be calculated appropriately, or the input torque T The estimation error of _IN becomes large. Therefore, the controllability of the shift control executed by the continuously variable transmission control unit 72 to achieve the target gear ratio γ ^* of the continuously variable transmission 18 while preventing belt slippage of the continuously variable transmission 18 is greatly increased. May be reduced. On the other hand, as the fail-safe, the actual speed ratio determined in advance the primary instruction hydraulic Pintgt and secondary command oil Pouttgt fixed to the stored constant value output as a hydraulic control command signal S _CVT of when it is not possible to calculate the γ It is also conceivable to perform shift control by FF control. However, in the case of such speed change control by FF control, the actual speed ratio γ of the continuously variable transmission 18 is determined to a certain value according to, for example, the actual input torque T _{IN and the} like in a wide vehicle speed range. There is a possibility that driving performance cannot be secured. For example, there is a possibility that ensuring acceleration performance when the vehicle starts and ensuring traveling performance at a relatively high vehicle speed cannot be achieved at the same time.

In view of this, the electronic control unit 50 of the present embodiment, in the event of a failure in which the actual speed ratio γ of the continuously variable transmission 18 cannot be detected (calculated), is set in advance in association with the vehicle speed V (output shaft rotational speed N _OUT ). Step-by-step shift control is performed by switching a plurality of types of target gear ratios (hereinafter referred to as “failure target gear ratios”) γ ^* f based on the output shaft rotational speed N _OUT. Run. That is, the continuously variable transmission control unit 72 performs the stepless transmission of the continuously variable transmission 18 by the FF control and the FB control in the normal time (normal time) when the actual transmission ratio γ of the continuously variable transmission 18 can be detected. Control (that is, shift control during normal time in which the gear ratio γ is continuously (steplessly) changed) is executed. On the other hand, the continuously variable transmission control unit 72 does not execute the continuously variable transmission control of the continuously variable transmission 18 only by the FF control at the time of the failure, but the stepped transmission of the continuously variable transmission 18 only by the FF control. Shift control (that is, a shift control at the time of a failure in which the speed ratio γ (target speed ratio γ ^* ) is changed stepwise (stepwise)) is executed.

FIG. 6 is a diagram showing a shift line (fail-time shift map) used at the time of failure corresponding to the target gear ratio γ ^* f at the time of failure, and corresponds to the normal-time shift map of FIG. In FIG. 6, the fail-time shift map is indicated by an ON line (up line) for stepwise upshifting the target speed ratio γ ^* as the vehicle speed V increases at power-on as indicated by a solid line, and by a broken line. The vehicle has an OFF line (down line) for downshifting the target speed ratio γ ^* in a stepwise manner as the vehicle speed V decreases during power off. In such a failure time shift map, the failure target speed ratio γ ^* f (= fail time target N _IN ^* f / N _OUT ) is set in advance so that the output shaft rotation speed N _OUT is a relatively low rotation speed range. In the low vehicle speed range, the target maximum speed ratio γmax ^* , which is the target speed ratio γ ^* on the minimum vehicle speed side, for controlling the actual speed ratio γ from the maximum speed ratio γmax to the vicinity of the maximum speed ratio γmax, and the output shaft rotational speed N _OUT The maximum vehicle speed side for controlling the actual gear ratio γ from the minimum gear ratio γmin to the vicinity of the minimum gear ratio γmin in the high vehicle speed range preset in the higher vehicle speed side than the low vehicle speed region in which the rotational speed range is relatively high of includes a target minimum gear ratio gamma] min ^* is the target gear ratio gamma ^*, is switched between the target maximum speed ratio .gamma.max ^* and the target minimum speed ratio gamma] min ^* based on the output shaft rotation speed N _OUT .

Further, in the fail speed shift map of FIG. 6, the target maximum speed ratio γmax ^* and the target minimum speed ratio γmin ^* are the adjacent fail time target speed ratio γ ^* f, and this adjacent fail time target speed ratio γ ^* Between f, downshift switching vehicle speed V ′ _DN for determining a downshift to the target maximum speed ratio γmax ^* and upshift switching vehicle speed V ′ for determining an upshift to the target minimum speed ratio γmin ^* _A predetermined hysteresis is provided between _UP . In order to avoid shift hunting in the shift control at the time of failure, this predetermined hysteresis is short-term switching of the target shift ratio γ ^* between the target maximum shift ratio γmax ^* and the target minimum shift ratio γmin ^*. This is a vehicle speed difference obtained in advance to prevent repetition in between.

Further, the downshift switching vehicle speed V ′ _DN for determining the downshift to the target maximum speed ratio γmax ^* is set such that the actual speed ratio γ becomes the maximum speed ratio γmax to the maximum speed ratio γmax before the vehicle stops, for example, in preparation for the next vehicle start. It is also a threshold set in advance so as to be in the vicinity of the maximum gear ratio γmax. _UP 'upshift switch speed V for determining the upshift to the target minimum speed ratio gamma] min ^* adjacent to _DN' downshift switch vehicle speed V, for example, proper acceleration performance at a relatively low speed range after the vehicle is started or it is a and the engine rotational speed N overspeed is reliably prevented in _E maintained, for relatively driving performance in the high speed range (high speed running performance) is appropriately secured at the target maximum speed ratio .gamma.max ^* This is also a threshold set in advance as the upper limit vehicle speed of the vehicle speed V range in which the vehicle can travel.

  More specifically, referring back to FIG. 3, the actual gear ratio detection impossibility determination means, that is, the actual gear ratio detection impossibility determination unit 74 determines whether the actual gear ratio γ cannot be calculated (detected), for example. The determination is made based on whether or not at least one of the speed sensor 54 and the output shaft rotation speed sensor 56 has failed. The actual gear ratio detection impossibility determination unit 74 determines, for example, whether or not at least one of the turbine rotation speed sensor 54 and the output shaft rotation speed sensor 56 has failed based on various input signals detected by the sensors. To do. If the continuously variable transmission control unit 72 determines that the actual transmission ratio γ can be calculated by, for example, the actual transmission ratio non-detectable determination unit 74, the normal transmission of the continuously variable transmission 18 by the FF control and the FB control is determined. Shift control (that is, stepless shift control of the continuously variable transmission 18) is executed.

The vehicle speed information acquisition means, that is, the vehicle speed information acquisition unit 76 acquires information on the vehicle speed V based on various input signals detected by each sensor, for example. Specifically, the vehicle speed information acquisition unit 76 determines that the actual gear ratio γ cannot be calculated because the actual gear ratio detection impossibility determination unit 74 has failed the turbine rotation speed sensor 54. Then, the output shaft rotational speed N _OUT which is the detection value of the output shaft rotational speed sensor 56 is obtained as it is as the vehicle speed V information. Further, the vehicle speed information acquisition unit 76 determines that the actual gear ratio γ cannot be calculated because the actual gear ratio detection impossibility determination unit 74 has failed the output shaft rotation speed sensor 56. The output shaft rotation speed N _OUT calculated based on the wheel rotation speed N _W that is a detection value of the speed sensor 58 is acquired as information on the vehicle speed V.

The fail-time gear shift determining means, that is, the fail-time gear shift determining unit 78 is determined by the continuously variable transmission control unit 72 when, for example, the actual gear ratio detection impossible determining unit 74 determines that the actual gear ratio γ cannot be calculated. Based on the vehicle speed V information acquired by the vehicle speed information acquisition unit 76 from the failure speed shift map as shown in FIG. 6 used in the stepped speed change control at the time of failure, the target maximum speed ratio γmax ^* and the target minimum The target gear ratio γ ^* f for failure to be switched is determined based on the gear ratio γmin ^* .

The continuously variable transmission control unit 72 determines the actual transmission ratio γ by the failure-time transmission determination unit 78 when, for example, the actual transmission ratio detection impossible determination unit 74 determines that the actual transmission ratio γ cannot be calculated. The target primary pressure Pin ^* and the target secondary pressure Pout ^* for calculating the failed target gear ratio γ ^* f are calculated. Specifically, the step-variable shift control at the time of failure by the continuously variable transmission control unit 72 cannot execute the FB control, and is a shift control only by the FF control. And the influence of individual variations of the hydraulic control circuit 100 cannot be offset. Therefore, even if there is an influence of such individual variations, the target primary pressure Pin ^* f for failure and the target secondary pressure Pout ^* f for failure for setting the target gear ratio γ ^* f for failure are set. . For example, when the continuously variable transmission control unit 72 determines that the target maximum transmission gear ratio γmax ^* is determined as the failure target transmission gear ratio γ ^* f to be switched by the failure transmission gearshift determination unit 78, the influence of the individual variation and the like is affected. Even if there is, the maximum primary transmission ratio target primary pressure Pin ^* (γmax) and the maximum transmission ratio that are obtained and stored in advance as the hydraulic pressure value that reliably controls the actual transmission ratio γ between the maximum transmission ratio γmax and the vicinity of the maximum transmission ratio γmax. Target secondary pressure Pout ^* (γmax) is calculated (set). On the other hand, the continuously variable transmission control unit 72, when the target minimum speed ratio γmin ^* is determined as the fail target speed ratio γ ^* f to be switched by the fail time shift determining part 78, the influence of the individual variation and the like. Even if there is a minimum gear ratio target primary pressure Pin ^* (γmin) and a minimum gear ratio that are obtained and stored in advance as a hydraulic pressure value that reliably controls the actual gear ratio γ between the minimum gear ratio γmin and the vicinity of the minimum gear ratio γmin. The specific target secondary pressure Pout ^* (γmin) is calculated (set).

The continuously variable transmission control unit 72 performs, for example, FF control, a fail-time target primary pressure Pin ^* f (for example, a maximum primary gear ratio target primary pressure Pin ^* (γmax) or a minimum primary gear ratio target primary pressure Pin ^* (γmin)). Primary instruction oil pressure Pintgt from which the engine speed is obtained, and target secondary pressure Pout ^* f at the time of failure (for example, the maximum secondary gear ratio target secondary pressure Pout ^* (γmax) or the minimum transmission ratio target secondary pressure Pout ^* (γmin)). determining the hydraulic Pouttgt and (calculated), and outputs to the hydraulic control circuit 100 a primary instruction hydraulic Pintgt and secondary command oil Pouttgt as hydraulic control command signal S _CVT. As described above, the continuously variable transmission control unit 72 determines that the actual transmission ratio γ cannot be calculated by the actual transmission ratio detection impossibility determination unit 74. Shift control at the time of failure (that is, stepped shift control of the continuously variable transmission 18) is executed.

The continuously variable transmission control unit 72 switches the target gear ratio γ ^* f at the time of failure between the target maximum speed ratio γmax ^* and the target minimum speed ratio γmin ^* , for example, to suppress the shift shock, for example, While sweeping (gradually changing) the primary command oil pressure Pintgt so that the changeover between the gear ratio target primary pressure Pin ^* (γmax) and the minimum gear ratio target primary pressure Pin ^* (γmin) gradually changes, The secondary command hydraulic pressure Pouttgt may be swept so that the switching between the maximum gear ratio target secondary pressure Pout ^* (γmax) and the minimum gear ratio target secondary pressure Pout ^* (γmin) gradually changes.

  FIG. 7 shows a control operation for ensuring the driving performance in a wide vehicle speed V range even when the main control operation of the electronic control unit 50, that is, when the actual gear ratio γ of the continuously variable transmission 18 cannot be detected. It is a flowchart explaining the operation, and is repeatedly executed with a very short cycle time of, for example, about several milliseconds to several tens of milliseconds.

In FIG. 7, first, in step (hereinafter, step is omitted) S10 corresponding to the actual gear ratio detection impossibility determination unit 74, for example, it is determined whether the actual gear ratio γ cannot be calculated (detected). . If the determination in S10 is negative, this routine is terminated. If the determination is positive, in S20 corresponding to the vehicle speed information acquisition unit 76, for example, based on various input signals detected by each sensor, the vehicle speed V (output Information on the shaft rotation speed N _OUT ) is acquired. Next, in S30 corresponding to the fail-time shift determination unit 78, for example, based on the vehicle speed V information obtained in S20 from the fail-speed shift map as shown in FIG. 6, the target maximum speed ratio γmax ^* and the target minimum The fail target speed ratio γ ^* f to be switched is determined based on the speed ratio γmin ^* . When the target maximum speed ratio γmax ^* is determined as the fail target speed ratio γ ^* f to be switched in S30, in S40 corresponding to the continuously variable transmission control unit 72, for example, the target maximum speed ratio only by FF control. A maximum gear ratio target primary pressure Pin ^* (γmax) and a maximum gear ratio target secondary pressure Pout ^* (γmax), which are predetermined hydraulic pressure values for realizing γmax ^* , are calculated. On the other hand, when the target minimum speed ratio γmin ^* is determined as the fail target speed ratio γ ^* f to be switched in S30, in S50 corresponding to the continuously variable transmission control unit 72, for example, the target is set only by FF control. A minimum gear ratio target primary pressure Pin ^* (γmin) and a minimum gear ratio target secondary pressure Pout ^* (γmin), which are predetermined hydraulic pressure values for realizing the minimum gear ratio γmin ^* , are calculated. Following S40 or S50, in S60 corresponding to the continuously variable transmission control unit 72, the maximum gear ratio target primary pressure Pin ^* (γmax) or the minimum gear ratio target primary pressure Pin ^* (γmin, for example, by FF control. )) And the secondary command hydraulic pressure Pouttgt from which the maximum gear ratio target secondary pressure Pout ^* (γmax) or the minimum gear ratio target secondary pressure Pout ^* (γmin)) can be obtained. command oil Pintgt and secondary command oil pressure Pouttgt is output to the hydraulic control circuit 100 as the hydraulic pressure control command signal S _CVT.

As described above, according to the present embodiment, when the actual speed ratio γ cannot be detected, the target speed ratio γ ^* f during failure (target maximum speed ratio γmax ^* , target minimum speed ratio γmin ^* ) is output shaft rotational speed N. _{Since stepwise} speed change control is performed by switching based on _OUT , ensuring acceleration performance with a gear ratio γ suitable for starting the vehicle and ensuring driving performance with a gear ratio γ suitable for a relatively high vehicle speed V Can be made compatible. Therefore, even when the actual speed ratio γ of the continuously variable transmission 18 cannot be detected, traveling performance in a wide vehicle speed V range can be ensured.

Further, according to the present embodiment, the failure target speed ratio γ ^* f is set so that the actual speed ratio γ is set to the maximum speed ratio in a preset low vehicle speed range where the output shaft rotational speed _NOUT is a relatively low rotational speed range. The target maximum speed ratio γmax ^* for controlling to γmax or the vicinity of the maximum speed ratio γmax and a preset high speed on the higher vehicle speed side than the low vehicle speed range where the output shaft rotational speed _NOUT is a relatively high rotational speed range. In the vehicle speed range, since the actual speed ratio γ includes the target minimum speed ratio γmin ^* for controlling the actual speed ratio γmin to the minimum speed ratio γmin vicinity, the actual speed ratio γ of the continuously variable transmission 18 cannot be detected. The target speed ratio γ ^* is switched to at least the target maximum speed ratio γmax ^* suitable for starting the vehicle in the low vehicle speed range, and the target minimum speed ratio γmin ^* suitable for the relatively high vehicle speed V in the high vehicle speed range. Can be switched. Therefore, ensuring acceleration performance at the start of the vehicle and ensuring traveling performance at a relatively high vehicle speed V can both be achieved appropriately.

Further, according to this embodiment, between the adjacent fail target speed ratios γ ^* f, the downshift switching vehicle speed V ′ _DN for determining a downshift and the upshift switching vehicle speed V for determining an upshift. 'since predetermined hysteresis between the _UP is provided, that the stepwise target speed ratio gamma ^* switching of between adjacent failure-time target speed ratio gamma ^{* f} are repeated in a short period of time it can be prevented Thus, shift hunting when the stepped shift control at the time of failure is executed is avoided.

Further, according to this embodiment, the downshift switching vehicle speed V ′ _DN for determining the downshift to the target maximum speed ratio γmax ^* is such that the actual speed ratio γ is the maximum speed ratio γmax or the maximum speed change before the vehicle stops. Since the threshold value is set in advance so as to be close to the ratio γmax, the vehicle can be prepared for the next vehicle start, and the acceleration performance at the time of the vehicle re-start is appropriately ensured. _UP 'upshift switch speed V for determining the upshift to the target minimum speed ratio gamma] min ^* adjacent to _DN' downshift switch vehicle speed V, the vehicle speed V range that can be run by the target maximum speed ratio .gamma.max ^* because it is a preset threshold value as an upper limit vehicle speed, the acceleration performance at a relatively low speed range after the vehicle is started is over-rotation of the appropriately sustained and the engine rotational speed N _E is reliably prevented. In addition, traveling performance (high-speed traveling performance) in a relatively high vehicle speed range is appropriately ensured.

Further, according to this embodiment, the actual gear ratio γ cannot be detected because it is at least one of when the input shaft rotational speed N _IN cannot be detected and when the output shaft rotational speed N _OUT cannot be detected. When the turbine rotation speed sensor 54 that substitutes the function of the input shaft rotation speed sensor for detecting the input shaft rotation speed N _IN or when the output shaft rotation speed sensor 56 fails, the acceleration performance at the start of the vehicle is relatively high. Limp home performance (for example, provisional travel performance, emergency travel performance, and retreat travel performance) can be appropriately ensured while achieving high travel performance at a vehicle speed V.

Further, according to this embodiment, since the value based on the detected value (turbine rotational speed _NT ) of the turbine rotational speed sensor 54 is used as the input shaft rotational speed _NIN , the shift control of the continuously variable transmission 18 is executed. , it is possible to eliminate an input rotation speed sensor for detecting an input shaft rotational speed N _iN, it is possible to reduce the cost. Further, when the input shaft rotational speed N _IN cannot be detected is when the turbine rotational speed _NT cannot be detected, the turbine rotational speed for detecting the turbine rotational speed _NT used as the input shaft rotational speed N _IN. When the sensor 54 fails, the limp home performance can be appropriately ensured by satisfying both the acceleration performance at the start of the vehicle and the traveling performance at the relatively high vehicle speed V. As described above, the present embodiment eliminates the input rotation speed sensor and performs the shift control of the continuously variable transmission 18 at a value based on the turbine rotation speed _NT , so that when the turbine rotation speed sensor 54 fails, This is a particularly useful invention for the absence of an alternative rotational speed sensor.

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

For example, in the above-described embodiment, the failure target speed ratio γ ^* f is set so as to switch the target speed ratio γ ^* between two shift speeds of the target maximum speed ratio γmax ^* and the target minimum speed ratio γmin ^*. However, the present invention is not limited to this, and the target speed ratio γ ^* may be set to be switched between three or more speed stages. For example, as shown in the failure shift map of FIG. 8, the target speed ratio γ ^* is switched between three shift speeds of the target maximum speed ratio γmax ^* , the target intermediate speed ratio γ1 ^*, and the target minimum speed ratio γmin ^*. It may be set to. In the failure shift map of FIG. 8, as in the failure shift map of FIG. 6, the downshift switching vehicle speed V ′ _DN and the upshift switching vehicle speed are between the adjacent failure target transmission gear ratios γ ^* f. A predetermined hysteresis is provided between V ′ _UP .

Further, in the above-described embodiment, when executing the shift control at the time of failure where the actual transmission ratio γ of the continuously variable transmission 18 cannot be detected, the output shaft rotational speed N _OUT is changed from the failure shift map as shown in FIG. Based on this, the target gear ratio γ ^* is switched stepwise, but it is not always necessary to use the failure time shift map. For example, the failure time target speed ratio gamma ^{* f} is carved similar to downshift switch speed V _'DN upshift switch speed V' _UP (Segmented) as preset step-varying target gear It may be stored as the ratio γ ^* .

In the above-described embodiment, the present invention has been described by exemplifying the vehicle 10 that does not include the input rotation speed sensor for detecting the input shaft rotation speed N _IN of the continuously variable transmission 18. The present invention can be applied even to a vehicle including a sensor. In short, the present invention can be applied to any vehicle that may cause a failure in which the actual transmission ratio γ of the continuously variable transmission 18 cannot be detected (calculated).

In the above-described embodiment, the torque converter 14 having the lock-up clutch 26 is used as the fluid transmission device. However, the lock-up clutch 26 is not necessarily provided, and instead of the torque converter 14, Other fluid transmissions such as a fluid coupling (fluid coupling) without torque amplification may be used. Further, when the forward / reverse switching device 16 functions as the starting mechanism, a starting mechanism such as a starting clutch is provided, or an engaging device or the like capable of connecting / disconnecting a power transmission path is provided, fluid transmission The device may not be provided. Further, in case that the starting clutch and the like can be provided in place of the torque converter 14, for example, the rotational speed of the engine speed N _E corresponding to the input shaft rotational speed N _IN, the value based on the engine rotational speed N _E an input shaft is used as the rotational speed _{N IN.}

  Further, the hydraulic control circuit 100 of the above-described embodiment has a configuration in which the hydraulic pressure supplied to the primary hydraulic cylinder 40c is directly controlled to be the primary pressure Pin, but is not limited thereto. For example, the present invention can be applied even to a hydraulic control circuit configured to generate the primary pressure Pin as a result of controlling the flow rate of hydraulic oil to the primary hydraulic cylinder 40c.

Further, in the hydraulic control circuit 100 of the above-described embodiment, the secondary pressure sensor 64 is provided on the secondary pulley 44 side, the gear ratio γ of the continuously variable transmission 18 is controlled on the primary pulley 40 side, and the secondary pulley 44 side In the above, the belt clamping pressure of the continuously variable transmission 18 is controlled, but the present invention is not limited to this. For example, a hydraulic pressure sensor is provided on the primary pulley 40 side, the gear ratio γ of the continuously variable transmission 18 is controlled on the secondary pulley 44 side, and the belt clamping pressure of the continuously variable transmission 18 is controlled on the primary pulley 40 side. The present invention can be applied even to a hydraulic control circuit configured as described above. Further, the primary pressure Pin (primary thrust Win is also agreed) and the secondary pressure Pout (secondary thrust Wout is also agreed) prevent the transmission belt 46 from slipping, and the primary thrust Win and the secondary thrust Wout are set in a mutual relationship. The hydraulic control circuit is configured to realize the gear ratio γ ^* , but is not limited thereto. For example, it may be a hydraulic control circuit configured to realize a target shift on one pulley side and a target belt clamping pressure on the other pulley side.

Further, in the above-described embodiment, the speed change control of the continuously variable transmission 18 by the FB control is executed based on the speed ratio deviation Δγ (= γ ^* −γ), but it is tired to use the speed ratio deviation Δγ as the deviation. It is an example. In short, this deviation may be a deviation between the target value and the actual value in the parameter corresponding to the gear ratio γ and 1: 1. For example, instead of the gear ratio deviation Δγ, the rotational deviation ΔN _IN (= N _IN ^* −N _IN ) between the target input shaft rotational speed N _IN ^* and the actual input shaft rotational speed N _IN , the target pulley position X ^* and the actual pulley A deviation ΔX (= X ^* −X) from the position X, a deviation ΔR (= R ^* −R) between the target belt engagement diameter R ^* and the actual belt engagement diameter R can be used.

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

18: Belt type continuously variable transmission (vehicle continuously variable transmission)
50: Electronic control device (control device)

Claims (5)

The vehicle continuously variable transmission power of a drive power source via a torque converter is transmitted, the actual speed ratio shift control so that the target gear ratio is executed, the control device for a vehicle continuously variable transmission Because
The actual gear ratio is calculated by using a value based on the detected value of the turbine rotation speed of the torque converter as the input shaft rotation speed of the continuously variable transmission for the vehicle,
When the turbine rotation speed cannot be detected, stepwise speed change control is executed by switching a plurality of types of target speed ratios that change stepwise in advance in association with the vehicle speed based on the vehicle speed. A control device for a continuously variable transmission for a vehicle. In a continuously variable transmission for a vehicle to which power of a driving force source is transmitted via a torque converter, the control device for the continuously variable transmission for vehicle is executed so that the actual transmission ratio becomes a target transmission ratio. Because
The actual gear ratio is calculated by using a value based on the detected value of the turbine rotation speed of the torque converter as the input shaft rotation speed of the continuously variable transmission for the vehicle,
When the output shaft rotational speed of the continuously variable transmission for the vehicle cannot be detected, a value based on the detected value of the wheel rotational speed is used as the vehicle speed, and a plurality of types of target shifts that change stepwise in advance in association with the vehicle speed. A control device for a continuously variable transmission for a vehicle, wherein stepwise shift control is executed by switching a ratio based on the vehicle speed. The plurality of types of target speed ratios are the target speed ratios on the lowest vehicle speed side for controlling the actual speed ratio to a speed ratio on the lowest vehicle speed side or a gear ratio in the vicinity of the lowest vehicle speed in a preset low vehicle speed range. In the high vehicle speed range preset on the higher vehicle speed side than the low vehicle speed region, the actual speed ratio is set to the highest vehicle speed side to control the actual gear ratio to the maximum vehicle speed side gear ratio or the gear ratio in the vicinity of the highest vehicle speed side. The control device for a continuously variable transmission for a vehicle according to claim 1 or 2 , further comprising a target gear ratio. Between the adjacent target speed ratios among the plurality of types of target speed ratios, between the downshift switching vehicle speed to the target speed ratio on the low vehicle speed side and the upshift switching vehicle speed to the target speed ratio on the high vehicle speed side. The control device for a continuously variable transmission for a vehicle according to any one of claims 1 to 3, wherein a predetermined hysteresis is provided. The downshift switching vehicle speed to the target gear ratio on the lowest vehicle speed side for controlling the actual gear ratio to the gear ratio on the lowest vehicle speed side or the gear ratio in the vicinity of the lowest vehicle speed side is the actual speed change before the vehicle stops. A threshold that is set in advance so that the ratio is a speed ratio on the minimum vehicle speed side or a speed ratio in the vicinity of the minimum vehicle speed side;
The upshift switching vehicle speed to the target gear ratio on the high vehicle speed side adjacent to the target gear ratio on the minimum vehicle speed side is set in advance as the upper limit vehicle speed in the vehicle speed range in which the vehicle can travel at the target gear ratio on the minimum vehicle speed side. The control device for a continuously variable transmission for a vehicle according to claim 4 , wherein the threshold value is a threshold value.

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