JP2008014362A - Controller of continuously variable transmission for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel consumption in the condition that an increase of belt clamping force is suppressed to be a necessary minimum value at the time of vehicle start toward ascent direction. <P>SOLUTION: Fuel consumption can be improved in the condition that the increase of the belt clamping force is suppressed to be the necessary minimum value in such a way that at the time of vehicle restart in an ascent direction, road surface gradient on which vehicle runs is judged to be steeper than a predetermined gradient by a steep slope judging means 164, that in the condition that hydraulic pressure inside drive side hydraulic cylinder 42c is judged to have been released by a start time drive side hydraulic pressure release judging means 166, a belt clamping force Pd at this time is raised higher than a normal belt clamping force Pd<SP>*</SP>set by a belt clamping force setting means 154 by a predetermined value by a belt clamping force controlling means 156, with the belt clamping force Pd raised only when belt slip easily happens at the time of vehicle start toward ascent direction in such a manner that the hydraulic pressure inside the drive side hydraulic cylinder 42c is released. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a continuously variable transmission for a vehicle having a pair of pulleys whose effective diameter is changed by a hydraulic actuator and a transmission belt wound around the pair of pulleys. The present invention relates to belt clamping pressure control when starting.

  Drive-side hydraulic actuator and driven-side pulley for changing the groove width of the drive-side pulley in a control device for a continuously variable transmission for a vehicle having a drive-side pulley, a driven-side pulley, and a belt wound around both pulleys A driven side hydraulic actuator for changing the groove width of the belt, and the belt clamping pressure is controlled by the driven side hydraulic actuator so that no slip occurs between the belt and both pulleys. When traveling over a predetermined vehicle speed where the rotational speed can be detected, the groove width of the driving pulley is changed by controlling the supply and discharge of hydraulic fluid to the driving hydraulic actuator based on the deviation between the target value and the actual value of the rotational speed. While the speed of the continuously variable transmission is changed, the predetermined speed is applied to the drive side hydraulic actuator when the vehicle is traveling below a predetermined vehicle speed whose rotation speed is difficult to detect. To the gear ratio of the continuously variable transmission to a predetermined gear ratio in a state where confined hydraulic oil in the drive side hydraulic actuator while the action of hydraulic pressure is well known.

  For example, when the vehicle travels above a predetermined vehicle speed, the hydraulic oil is supplied to the drive-side hydraulic actuator, thereby narrowing the groove width of the drive-side pulley and upshifting the continuously variable transmission. As the hydraulic oil is discharged, the groove width of the driving pulley is widened and the continuously variable transmission is downshifted. Further, when the vehicle is stopped, so-called closing control is performed in which the hydraulic oil is confined in the drive side hydraulic actuator, so that the speed ratio of the continuously variable transmission is set to the minimum speed side speed ratio. That is, the belt is returned to the maximum deceleration state.

  By the way, if the brake is released and the vehicle slips in the direction opposite to the starting direction when the vehicle restarts in the ascending direction after stopping on a steep uphill road, the driving direction and the rotating direction are different and the same belt Since the transmission torque capacity of the belt is different even under pressure, the belt transmission torque capacity is lower during reverse rotation forward drive than during forward rotation forward drive. When the clamping pressure is controlled, there is a possibility that the transmission torque capacity is insufficient and the belt slips.

  In order to avoid the occurrence of such belt slip, for example, in Patent Document 1, when the road surface gradient is a steep climbing road having a predetermined gradient or more, the belt clamping pressure at this time is stored in advance. A control device for a belt type continuously variable transmission for a vehicle has been proposed in which the belt clamping pressure is set to be higher than the normal belt clamping pressure set from the above relationship.

JP 2003-343707 A JP 2002-340158 A

  However, when the hydraulic pressure is applied to the drive side hydraulic actuator, for example, during the above-described closing control, the vehicle may not slide down even if the belt clamping pressure is not higher than usual when the vehicle starts to reappear suddenly. Yes, as shown in the above-mentioned Patent Document 1, if the belt clamping pressure is increased uniformly even in such a case as a steep climbing road, the transmission efficiency is deteriorated and energy loss is increased, resulting in poor fuel consumption. There was a possibility of becoming.

  The present invention has been made in the background of the above circumstances, and the object of the present invention is to provide a continuously variable vehicle for improving fuel efficiency by increasing the belt clamping pressure to a minimum when starting a vehicle in an ascending direction. An object of the present invention is to provide a transmission control device.

  To achieve this object, the gist of the invention according to claim 1 is that (a) a driving pulley, a driven pulley, and both pulleys are provided in a power transmission path between a driving power source and driving wheels. In a vehicle equipped with a continuously variable transmission having a wound belt, a driven hydraulic actuator for changing the groove width of the driving pulley and a driven for changing the groove width of the driven pulley A side hydraulic actuator, and performs shifting by supplying and discharging hydraulic oil to and from the driving side hydraulic actuator, and belt driven pressure is applied by the driven side hydraulic actuator so that slippage does not occur between the belt and both pulleys. (B) a steep slope determining means for determining whether or not a road surface gradient on which the vehicle travels is a slope that exceeds a predetermined gradient; ) When starting the vehicle, determine whether the hydraulic pressure in the drive-side hydraulic actuator has been released or not, (d) When starting the vehicle in the ascending direction, the steep slope determination means The belt clamping pressure at this time is determined on the condition that it is determined that the road exceeds the gradient and that the hydraulic pressure in the drive side hydraulic actuator has been released by the drive side hydraulic pressure drop judging means at the time of starting. And an uphill road starting belt clamping pressure control means for making it higher than a normal belt clamping pressure set from a previously stored relationship.

  In this way, when starting the vehicle in the ascending direction, the steep slope determining means determines that the road surface gradient on which the vehicle travels exceeds a predetermined slope, and the driving side hydraulic pressure drop-off determining means determines the drive side hydraulic pressure. On the condition that the hydraulic pressure in the actuator is judged to have dropped, the belt clamping pressure at this time is determined by the belt clamping pressure control means at the time of starting uphill road from the normal belt clamping pressure set from the relationship stored in advance. Therefore, the belt clamping pressure is increased only when the hydraulic pressure in the drive side hydraulic actuator is released and the belt slips easily when starting the vehicle in the climbing direction. Fuel consumption can be improved.

  Here, according to a second aspect of the present invention, in the control device for a continuously variable transmission for a vehicle according to the first aspect, the control device applies a predetermined hydraulic pressure to the drive side hydraulic actuator in a vehicle state of a predetermined vehicle speed or less. The gear ratio of the continuously variable transmission is set to a predetermined gear ratio in a state in which hydraulic oil is confined in the drive side hydraulic actuator while acting, and the gear ratio of the continuously variable transmission is the lowest when the vehicle is stopped. Under the condition that the most deceleration determining means for determining whether or not the speed side gear ratio is present and that the speed ratio of the continuously variable transmission is determined to be the lowest speed side gear ratio by the most deceleration determining means, When starting the vehicle, a start shift control means for temporarily executing a down shift operation for discharging hydraulic oil from the drive side hydraulic actuator so that the transmission gear ratio of the continuously variable transmission becomes the lowest speed shift ratio. More The starting drive side hydraulic pressure drop determining means determines whether or not the hydraulic pressure in the drive side hydraulic actuator is released based on whether or not the downshift operation is being executed by the start shift speed control means. Is. In this way, when the hydraulic oil is confined in the drive side hydraulic actuator in a vehicle state below a predetermined vehicle speed, an upshift occurs due to the hydraulic pressure applied to the drive side hydraulic actuator at the start. In order to prevent this, the belt clamping pressure is increased only when the downshift operation is temporarily executed by the starting shift control means so that the transmission gear ratio of the continuously variable transmission is set to the lowest speed gear ratio. Thus, the occurrence of belt slip can be avoided and the fuel consumption can be improved by increasing the belt clamping pressure to the minimum necessary.

  Here, preferably, in the continuously variable transmission, the normal shift control of the continuously variable transmission performed in a vehicle state in which the vehicle speed exceeds a predetermined vehicle speed, for example, a rotation speed of a rotating member that can be detected by a rotation speed sensor. For example, the target gear ratio is obtained according to a predetermined gear ratio, and the drive side hydraulic cylinder is actuated as a drive side hydraulic actuator provided integrally with the drive side pulley so that the actual gear ratio becomes the target gear ratio. The gear ratio of the drive pulley is changed by changing the groove width of the drive pulley by supplying and discharging oil, and the target rotation speed on the input side (drive source side) according to the vehicle speed and output rotation speed (drive wheel rotation speed) Feedback control of the gear ratio by changing the groove width of the drive pulley by supplying and discharging hydraulic oil to the drive hydraulic cylinder so that the actual input rotation speed becomes the target rotation speed Etc. or it can employ various aspects.

  The above-mentioned predetermined speed change conditions are set by a map or an arithmetic expression using, for example, driving conditions such as a driver output request amount (acceleration request amount) such as an accelerator operation amount and a vehicle speed (corresponding to an output rotation speed) as parameters. Is done.

  Further, the gear ratio of the continuously variable transmission is set to a predetermined value as a state in which hydraulic oil is confined in a drive-side hydraulic actuator that is executed in a vehicle state when the feedback control is difficult such as when traveling at a low vehicle speed below a predetermined vehicle speed. In the hydraulic control for changing the gear ratio, the hydraulic pressure of the driving hydraulic cylinder and the hydraulic pressure of the driven hydraulic cylinder are controlled independently, and a predetermined thrust ratio τ (= the hydraulic pressure of the driven hydraulic cylinder × the pressure receiving area of the driven hydraulic cylinder / The hydraulic pressure of the drive side hydraulic cylinder may be controlled so that the hydraulic pressure of the drive side hydraulic cylinder x the pressure receiving area of the drive side hydraulic cylinder). For example, the thrust ratio control in which the hydraulic pressure of the driven hydraulic cylinder is introduced as a pilot pressure The hydraulic pressure of the drive side hydraulic cylinder is controlled based on the control pressure output from the thrust ratio control valve. By Rukoto, it is desirable to configure such that a predetermined thrust ratio tau.

  Preferably, an engine that is an internal combustion engine such as a gasoline engine or a diesel engine is widely used as the driving power source. Furthermore, an electric motor or the like may be used in addition to the engine as an auxiliary driving power source. Alternatively, only an electric motor may be used as a driving power source.

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

  FIG. 1 is a skeleton diagram illustrating the configuration of a vehicle drive device 10 to which the present invention is applied. This vehicle drive device 10 is a horizontal automatic transmission, which is suitably employed in an FF (front engine / front drive) type vehicle, and includes an engine 12 as a driving power source. The output of the engine 12 composed of an internal combustion engine is the crankshaft of the engine 12, the torque converter 14 as a fluid transmission device, the forward / reverse switching device 16, the belt type continuously variable transmission (CVT) 18, the reduction gear. It is transmitted to the differential gear device 22 via the device 20 and distributed to the left and right drive wheels 24L, 24R.

  The torque converter 14 includes a pump impeller 14p connected to the crankshaft of the engine 12 and a turbine impeller 14t connected to the forward / reverse switching device 16 via a turbine shaft 34 corresponding to an output side member of the torque converter 14. And power transmission is performed via a fluid. A lock-up clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t, and a lock-up control valve (L not shown) in the hydraulic control circuit 100 (see FIGS. 2 and 3) is provided. The hydraulic pressure supply to the engagement side oil chamber and the release side oil chamber is switched by the (C / C control valve) or the like, thereby being engaged or released. The turbine impeller 14t is rotated integrally. The pump impeller 14p has a hydraulic pressure for controlling the transmission of the continuously variable transmission 18, generating a belt clamping pressure, controlling the engagement release of the lockup clutch 26, or supplying lubricating oil to each part. Is coupled to a mechanical oil pump 28 that is generated by being driven to rotate by the engine 12.

  The forward / reverse switching device 16 is composed mainly of a forward clutch C1, a reverse brake B1, and a double pinion type planetary gear device 16p, and the turbine shaft 34 of the torque converter 14 is integrally connected to the sun gear 16s. The input shaft 36 of the continuously variable transmission 18 is integrally connected to the carrier 16c, while the carrier 16c and the sun gear 16s are selectively connected via the forward clutch C1, and the ring gear 16r is connected to the reverse brake B1. And is fixed to the housing selectively. The forward clutch C1 and the reverse brake B1 correspond to an intermittent device, both of which 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 integral rotation state, whereby the turbine shaft 34 is directly connected to the input shaft 36, and the forward power The 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) the reverse power transmission path, and the input shaft 36 is connected to the turbine shaft 34. On the other hand, it is rotated in the opposite 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 continuously variable transmission 18 is an input side member provided on the input shaft 36, a drive side pulley (primary pulley, primary sheave) 42 having a variable effective diameter, and an output side member provided on the output shaft 44. A driven pulley (secondary pulley, secondary sheave) 46 having a variable diameter and a transmission belt 48 wound around these variable pulleys 42, 46, and the variable pulleys 42, 46 and the transmission belt 48 are provided. Power is transmitted via the frictional force between them.

The variable pulleys 42 and 46 are fixed rotation bodies 42 a and 46 a fixed to the input shaft 36 and the output shaft 44, respectively, and are not rotatable relative to the input shaft 36 and the output shaft 44 and are movable in the axial direction. Driven hydraulic cylinder (primary pulley side hydraulic cylinder) 42c and driven side hydraulic cylinder (secondary pulley side) as hydraulic actuators for applying thrust to change the V-groove width between the movable rotating bodies 42b and 46b provided Hydraulic cylinder) 46c, and the hydraulic fluid supply / discharge flow rate to the drive side hydraulic cylinder 42c is controlled by the hydraulic control circuit 100, so that the V groove widths of both variable pulleys 42, 46 change. As a result, the engagement diameter (effective diameter) of the transmission belt 48 is changed, and the gear ratio γ (= input shaft rotational speed N _IN / output shaft) The rotational speed N _OUT ) is continuously changed. The secondary pressure (hereinafter referred to as belt clamping pressure) Pd, which is the hydraulic pressure of the driven hydraulic cylinder 46c, is regulated by the hydraulic control circuit 100, so that the belt clamping pressure is reduced so that the transmission belt 48 does not slip. Be controlled. As a result of such control, a primary pressure (hereinafter referred to as shift 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 for controlling the vehicle drive device 10 of FIG. 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. By performing signal processing, output control of the engine 12, shift control of the continuously variable transmission 18, belt clamping pressure control, torque capacity control of the lockup clutch 26, and the like are executed. This is divided into control and hydraulic control for the continuously variable transmission 18 and the lockup clutch 26.

The electronic control unit 50, representing the crankshaft rotation speed corresponding to the engine rotational speed crankshaft detected by the sensor 52 rotation angle (position) A _{CR (°)} and the rotational speed of the engine 12 (engine rotational speed) N _E Signal, a signal representing the rotational speed (turbine rotational speed) _NT of the turbine shaft 34 detected by the turbine rotational speed sensor 54, and an input that is the input rotational speed of the continuously variable transmission 18 detected by the input shaft rotational speed sensor 56. rotational speed (input shaft rotational speed) signal representing the N _iN of the shaft 36, a vehicle speed sensor (output shaft rotation speed sensor) 58 by the rotational speed (output of the output shaft 44 is the output rotational speed of the continuously variable transmission 18 detected axis rotation speed) N _OUT ie vehicle speed signal representing a vehicle speed V corresponding to the output shaft speed N _OUT, en detected by the throttle sensor 60 Intake pipe 32 throttle valve opening signal representing the throttle valve opening theta _TH of the electronic throttle valve 30 provided in (see FIG. 1) of the emission 12, the cooling water temperature T _W of the engine 12 detected by a coolant temperature sensor 62 signals representative signal representative of the oil temperature T _CVT of a hydraulic circuit of the continuously variable such as transmission 18 detected by the CVT oil temperature sensor 64, the accelerator opening is an operation amount of the accelerator pedal 68 detected by the accelerator opening sensor 66 an accelerator opening signal representative of the acc, brake operation signal indicating whether B _ON operation of the foot brake is a service brake, which is detected by a foot brake switch 70, a lever position (operation of the shift lever 74 detected by a lever position sensor 72 position) operation position signal representative of the P _SH, the front-rear direction of the vehicle detected by the acceleration sensor 76 Such as a signal representing the acceleration G is supplied.

Further, the electronic control unit 50 receives an engine output control command signal S _E for controlling the output of the engine 12, for example, a throttle signal for driving a throttle actuator 78 for controlling opening and closing of the electronic throttle valve 30, and a fuel injection device 80. An injection signal for controlling the amount of fuel injected from the engine, an ignition timing signal for controlling the ignition timing of the engine 12 by the ignition device 82, and the like are output. Further, a command for driving the solenoid valve DS1 and the solenoid valve DS2 for controlling the flow of hydraulic fluid to the shift control command signal S _T for example drive side hydraulic cylinder 42c for changing the speed ratio γ of the continuously variable transmission 18 signal, clamping pressure for causing adjusting clamping pressure of the transmission belt 48 control command signal S _B for example a command signal for driving a linear solenoid valve SLS for pressurizing the belt clamping pressure Pd adjusted, the linear solenoid valve for controlling the line pressure P _L A command signal or the like for driving the SLT is output to the hydraulic control circuit 100.

  The shift lever 74 is arranged, for example, in the vicinity of the driver's seat and is sequentially positioned in five lever positions “P”, “R”, “N”, “D”, and “L” (see FIG. 3). Any one of them is manually operated.

  The “P” position (range) releases the power transmission path of the vehicle drive device 10, that is, a neutral state (neutral state) where the power transmission of the vehicle drive device 10 is interrupted, and is mechanically output by the mechanical parking mechanism. The parking position (position) for preventing (locking) the rotation of 44, the “R” position is the reverse traveling position (position) for reversely rotating the output shaft 44, and the “N” position. Is a neutral position (position) for setting the neutral state in which the power transmission of the vehicle drive device 10 is interrupted, and the “D” position establishes an automatic transmission mode within a transmission range that allows the transmission of the continuously variable transmission 18. This is a forward travel position (position) that allows automatic shift control to be executed, and the “L” position is operated by a strong engine brake. An engine brake position (position). Thus, the “P” position and the “N” position are non-traveling positions that are selected when the vehicle is not traveling, and the “R” position, the “D” position, and the “L” position are when the vehicle is traveling. This is the selected driving position.

  FIG. 3 shows the main part of the hydraulic control circuit 100 relating to the belt clamping pressure control, the transmission gear ratio control of the continuously variable transmission 18, and the engagement hydraulic pressure control of the forward clutch C1 or the reverse brake B1 accompanying the operation of the shift lever 74. FIG. In FIG. 3, the hydraulic control circuit 100 continuously changes the clamping pressure control valve 110 that regulates the belt clamping pressure Pd that is the hydraulic pressure of the driven hydraulic cylinder 46 c so that the transmission belt 48 does not slip, and the speed ratio γ continuously changes. The transmission ratio control valve UP114 and the transmission ratio control valve DN116 that control the flow rate of the hydraulic oil to the drive side hydraulic cylinder 42c so that the ratio between the transmission pressure Pin and the belt clamping pressure Pd is a predetermined relationship. A ratio control valve 118, a forward clutch C1, and a reverse brake B1 are provided with a manual valve 120 that mechanically switches the oil path according to the operation of the shift lever 74 so as to be engaged or released.

The line pressure P _L as source pressure working oil pressure output (generated) from the mechanical oil pump 28 which is rotated by the engine 12, for example, by the primary regulator valve (line pressure regulating valve) 122 of the relief type The pressure is adjusted to a value according 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. Modulator pressure P _M, as well is used as the basic pressure of the control oil pressure P _SLS is the output hydraulic pressure of the control pressure P _SLT and the linear solenoid valve SLS, by the electronic control unit 50 by the output hydraulic pressure of the solenoid valve DS1 that is duty-controlled a used as the basic pressure of a certain control oil pressure P _DS1 and the control pressure P _DS2 is the output hydraulic pressure of the solenoid valve DS2, the modulator valve 124 to line pressure P _L as source pressure adapted to be pressure regulated to a constant pressure ing. Output hydraulic pressure _{P LM2} is adapted to line pressure _{P L} to be pressure regulated on the basis of the control hydraulic pressure _{P SLT} by the line pressure modulator NO.2 valve 126 as an original pressure.

In the manual valve 120, the output oil pressure _PLM2 is supplied to the input port 120a. When the shift lever 74 is operated to the “D” position or the “L” position, the output hydraulic pressure _PLM2 is supplied to the forward clutch C1 via the forward output port 120f as the forward travel output pressure and the reverse brake. The oil passage of the manual valve 120 is switched so that the hydraulic oil in B1 is drained (discharged) to the atmospheric pressure, for example, from the reverse output port 120r through the discharge port EX, and the forward clutch C1 is engaged and reversely moved. The brake B1 is released.

Further, when the shift lever 74 is operated to the "R" position, output pressure P _LM2 is the hydraulic fluid in the fed and the forward clutch C1 to the reverse brake B1 via the reverse output port 120r as reverse running output pressure Is switched from the forward output port 120f through the discharge port EX to the atmospheric pressure, for example, so that the oil passage of the manual valve 120 is switched, the reverse brake B1 is engaged, and the forward clutch C1 is released. Be made.

  When the shift lever 74 is operated to the “P” position and the “N” position, the oil path from the input port 120a to the forward output port 120f and the oil path from the input port 120a to the reverse output port 120r are both And the oil passage of the manual valve 120 is switched so that the hydraulic oil in the forward clutch C1 and the reverse brake B1 is drained from the manual valve 120, and both the forward clutch C1 and the reverse brake B1 are connected. Be released.

The speed ratio control valve UP114 is up to close the suppliable and output port 114k from the input port 114i to the line pressure P _L by being movable in the axial direction to the drive pulley 42 through the output port 114j The spool valve element 114a is positioned at the shift position and the original position where the driving pulley 42 is communicated with the input / output port 114k via the input / output port 114j, and the spool valve element 114a is biased toward the original position side. A spring 114b as an urging means, an oil chamber 114c that accommodates the spring 114b and receives the control oil pressure _PDS2 to _apply a thrust toward the original position to the spool valve element 114a, and the spool valve element 114a the control oil pressure P _DS1 to apply a thrust force toward the shift position side And a only put the oil chamber 114d.

Further, the transmission ratio control valve DN116 is provided so as to be movable in the axial direction, whereby a downshift position where the input / output port 116j communicates with the discharge port EX and an original position where the input / output port 116j communicates with the input / output port 116k. A spool valve element 116a positioned at the first position, a spring 116b as an urging means for urging the spool valve element 116a toward the original position, and a spring 116b that accommodates the spool valve element 116a in the original position side. An oil chamber 116c that receives the control hydraulic pressure _PDS1 to apply a thrust toward the engine, and an oil chamber 116d that receives the control hydraulic pressure _PDS2 to apply a thrust toward the downshift position to the spool valve element 116a. .

In the transmission ratio control valve UP114 and the transmission ratio control valve DN116 thus configured, in the closed state in which the spool valve element 114a is held in the original position in accordance with the urging force of the spring 114b as shown in the left half of the center line, The input / output port 114j and the input / output port 114k are in communication with each other, and the hydraulic oil in the drive pulley 42 (drive hydraulic cylinder 42c) is allowed to flow to the input / output port 116j. In the closed state in which the spool valve element 116a is held in the original position according to the urging force of the spring 116b as shown in the right half of the center line, the input / output port 116j and the input / output port 116k are communicated with each other, and the thrust ratio it is allowed that the thrust ratio control oil pressure P _tau from control valve 118 to flow to the input-output port 114k.

Further, when the control oil pressure _PDS1 is supplied to the oil chamber 114d, the spool valve element 114a is increased against the urging force of the spring 114b by a thrust according to the control oil pressure _PDS1 as shown in the right half of the center line. is moved to the shift position side, the line pressure _{P L} is supplied to the control oil pressure _{P DS1} to the corresponding flow rate at the input port output from 114i port 114j menstrual driving side hydraulic cylinder 42c, input and output ports 114k is blocked Accordingly, the flow of the hydraulic oil to the speed ratio control valve DN116 side is prevented. As a result, the transmission pressure Pin is increased, the V groove width of the drive pulley 42 is reduced, and the transmission ratio γ is reduced, that is, the continuously variable transmission 18 is upshifted.

When the control oil pressure _PDS2 is supplied to the oil chamber 116d, the spool valve element 116a is lowered against the urging force of the spring 116b by the thrust according to the control oil pressure _PDS2 , as shown in the left half of the center line. The oil is moved to the shift position side, and the hydraulic oil in the drive side hydraulic cylinder 42c is discharged from the input / output port 114j through the input / output port 114k and further through the input / output port 116j from the discharge port EX at a flow rate corresponding to the control oil pressure _PDS2 . As a result, the transmission pressure Pin is reduced, the V groove width of the drive pulley 42 is increased, and the transmission ratio γ is increased, that is, the continuously variable transmission 18 is downshifted.

Thus, the line pressure P _L is the shift pressure Pin A used as the basic pressure of the control oil pressure P _DS1 is input to be output to the speed ratio control valve UP114 the line pressure P _L is the driving side hydraulic cylinder 42c When the shift pressure Pin is increased and continuously upshifted and the control hydraulic pressure _PS2 is output, the hydraulic oil in the drive side hydraulic cylinder 42c is discharged from the discharge port EX, and the shift pressure Pin is lowered. Downshifted continuously.

For example, as shown in FIG. 4, it is actually determined from a previously stored relationship (shift map) between the vehicle speed V and the target input shaft rotational speed N _IN ^* that is the target input rotational speed of the continuously variable transmission 18 using the accelerator opening Acc as a parameter. The target input shaft rotational speed N _IN ^* set based on the vehicle state indicated by the vehicle speed V and the accelerator opening Acc matches the actual input shaft rotational speed (hereinafter referred to as the actual input shaft rotational speed) N _IN. As described above, the speed change of the continuously variable transmission 18 is executed by feedback control in accordance with the difference (deviation) ΔN _IN (= N _IN ^* −N _IN ), that is, the hydraulic oil for the drive side hydraulic cylinder 42c. By supplying and discharging, the V-groove widths of both variable pulleys 42 and 46 are changed, and the speed ratio γ is continuously changed by feedback control.

The shift map in FIG. 4 corresponds to the shift conditions, and the target input shaft rotational speed N _IN ^* is set such that the larger the vehicle speed V is and the larger the accelerator opening Acc is, the larger the gear ratio γ is. Further, since the vehicle speed V corresponds to the output shaft rotation speed _{N OUT,} which is the target value of the input shaft rotational speed _{N IN} target input shaft rotational speed _{N IN} ^* is the target speed ratio ^{_{γ * (= N IN * /}} N OUT) And is determined within the range of the minimum speed ratio γmin and the maximum speed ratio γmax of the continuously variable transmission 18.

Further, the control hydraulic pressure _PDS1 is supplied to the oil chamber 116c of the transmission ratio control valve DN116, and regardless of the control hydraulic pressure _PDS2 , the transmission ratio control valve DN116 is closed to limit the downshift, while the control hydraulic pressure _{PDS2 changes} the speed. The oil ratio is supplied to the oil chamber 114c of the ratio control valve UP114, and regardless of the control oil pressure _PDS1 , the transmission ratio control valve UP114 is closed to prohibit the upshift. That is, the control when the hydraulic _{P DS1} and the control pressure _{P DS2} are not supplied together but of course, also, the speed change ratio control valve UP114 and speed ratio control valve when the control oil pressure _{P DS1} and the control pressure _{P DS2} is supplied together Each of the DNs 116 is in a closed state held in its original position. As a result, one of the solenoid valves DS1 and DS2 does not function due to a failure in the electrical system, and a sudden upshift occurs even when the control hydraulic pressure _PDS1 or the control hydraulic pressure _PDS2 continues to be output at the maximum pressure. It is possible to prevent a downshift or a belt slip due to the sudden shift.

The clamping force control valve 110, via an output port 110t by opening and closing an input port 110i to the line pressure P _L from the input port 110i by being movable in the axial direction to the driven side pulley 46 and the thrust ratio control valve 118 The spool valve element 110a that can supply the belt clamping pressure Pd, the spring 110b as an urging means that urges the spool valve element 110a in the valve opening direction, and the spring 110b is accommodated and opened to the spool valve element 110a. feedback oil accepting an oil chamber 110c that receives the control oil pressure P _SLS to apply a thrust force of the valve direction, the belt clamping pressure Pd output from the output port 110t to apply thrust in the valve closing direction to the spool valve element 110a Applying thrust in the valve closing direction to the chamber 110d and the spool valve element 110a And an oil chamber 110e that accepts modulator pressure P _M to.

In the clamping pressure control valve 110 thus configured, by the transmission belt 48 is line pressure P _L is continuously regulated pressure control control oil pressure P _SLS so as not slip as a pilot pressure, an output port 110t From this, the belt clamping pressure Pd is output. Thus, the line pressure P _L is used as the basic pressure of the belt clamping pressure Pd.

For example, as shown in FIG. 5, the accelerator opening degree Acc corresponding to the transmission torque is used as a parameter, and is experimentally obtained and stored in advance so as not to cause belt slip between the gear ratio γ and the required hydraulic pressure (belt clamping pressure) Pd ^*. From the relationship (belt clamping pressure map), the belt of the driven hydraulic cylinder 46c is obtained so that the belt clamping pressure Pd ^* determined (calculated) based on the vehicle state indicated by the actual gear ratio γ and the accelerator opening Acc is obtained. The clamping pressure Pd is controlled, and the belt clamping pressure Pd ^*, that is, the frictional force between the variable pulleys 42 and 46 and the transmission belt 48 is increased or decreased according to the belt clamping pressure Pd.

The thrust ratio control valve 118, a thrust ratio control oil pressure P the line pressure _{P L} by opening and closing an input port 118i by being movable in the axial direction from the input port 118i via an output port 118t to the speed ratio control valve DN116 a spool valve element 118a that can supply _τ , a spring 118b as an urging means that urges the spool valve element 118a in the valve opening direction, and the spring 118b is accommodated in the valve opening direction in the valve opening direction. an oil chamber 118c that receives the belt clamping pressure Pd to apply a thrust force, a feedback oil chamber for receiving the thrust ratio control oil pressure P _tau output from the output port 118t to apply a thrust force in the valve closing direction to the spool valve element 118a 118d.

In the thrust ratio control valve 118 configured as described above, the pressure receiving area of the belt clamping pressure Pd in the oil chamber 118c a, the pressure receiving area of the thrust ratio control oil pressure P _tau in the feedback oil chamber 118d b, the biasing force of the spring 118b When F _S, an equilibrium state in the following equation (1).
_Pτ × b = Pd × a + F _S (1)
Therefore, the thrust ratio control oil pressure _Pτ is expressed by the following equation (2) and is proportional to the belt clamping pressure Pd.
_Pτ = Pd × (a / b) + F _S / b (2)

Then, the control oil pressure _P or _DS1 and the control pressure _{P DS2} is not supplied together, or the predetermined pressure or more control pressure _{P DS1} and the predetermined pressure or more control pressure _{P DS2} is both supplied, the speed ratio control valve UP114 and the speed ratio control when the valve DN116 has both been a closed state is held in the original position, consistent since the thrust ratio control oil pressure P _tau is supplied to the drive side hydraulic cylinder 42c, and the transmission pressure Pin thrust ratio control oil pressure P _tau Be made. That is, the shift pressure Pin and the belt clamping pressure Pd kept in a predetermined relationship the ratio between the thrust ratio control oil pressure P _tau i.e. the shift pressure Pin is outputted by the thrust ratio control valve 118.

For example, because of the accuracy of the input shaft rotation speed sensor 56 and the vehicle speed sensor 58, the detection accuracy of the input shaft rotation speed _NIN and the vehicle speed V is inferior in a low vehicle speed state below a predetermined vehicle speed V ′. Instead of feedback control of the gear ratio γ for eliminating the rotational speed difference (deviation) ΔN _IN at the time of starting, for example, neither the control hydraulic pressure P _DS1 nor the control hydraulic pressure P _DS2 is supplied, and the gear ratio control valve UP114 and the gear ratio control valve A so-called closing control is performed in which all the DNs 116 are closed. As a result, the shift pressure Pin proportional to the belt clamping pressure Pd is supplied to the drive side hydraulic cylinder 42c so that the ratio between the transmission pressure Pin and the belt clamping pressure Pd is a predetermined relationship during low vehicle speed traveling or starting. Thus, the belt slip of the transmission belt 48 from the time when the vehicle is stopped to the extremely low vehicle speed is prevented, and at this time, for example, the thrust ratio τ corresponding to the maximum gear ratio γmax (= driven hydraulic cylinder thrust W _OUT / driving side hydraulic cylinder) Thrust W _IN ; W _OUT is the belt clamping pressure Pd × the pressure receiving area of the driven hydraulic cylinder 46c, and W _IN is the speed change pressure Pin × the pressure receiving area of the driving hydraulic cylinder 42c). When (a / b) and F _S / b in the first term on the right side of 2) are set, a good start is performed at the maximum gear ratio γmax or a gear ratio γmax ′ in the vicinity thereof. The predetermined vehicle speed V ′ is a lower limit vehicle speed at which a predetermined feedback control can be executed as a vehicle speed V at which the rotational speed of the predetermined rotating member, for example, the input shaft rotational speed _NIN cannot be detected. For example, it is set to about 2 km / h.

FIG. 6 shows the relationship obtained and stored in advance between the speed ratio γ and the thrust ratio τ using the vehicle speed V as a parameter, and the first term (a It is a figure which shows an example when / b) is set. The parameter of the vehicle speed V shown by the one-dot chain line in FIG. 6 is a thrust ratio τ calculated in consideration of the centrifugal hydraulic pressure in the drive side hydraulic cylinder 42c and the driven side hydraulic cylinder 46c, and the intersections with the solid lines (V ₀ , V ₂₀ , V ₅₀ ) obtains a gear ratio γ as a predetermined gear ratio that can be held during the closing control. For example, as shown in FIG. 6, in the continuously variable transmission 18 according to this embodiment, the maximum speed ratio γmax can be maintained as a predetermined speed ratio when the vehicle speed V is 0 km / h, that is, the closing control is performed while the vehicle is stopped. .

FIG. 7 is a functional block diagram for explaining the main part of the control function by the electronic control unit 50. In FIG. 7, the target input rotation setting means 150 is configured to change the input shaft rotation speed N _IN based on the vehicle state indicated by the actual vehicle speed V and the accelerator opening Acc from a shift map stored in advance as shown in FIG. Set the target input shaft rotational speed N _IN ^* sequentially.

The shift control means 152 makes the actual input shaft rotational speed N _IN coincide with the target input shaft rotational speed N _IN ^* set by the target input rotational setting means 150, that is, the rotational speed difference (deviation) ΔN _IN (= N _IN ^* −N _IN ), the shift of the continuously variable transmission 18 is executed by feedback control according to the rotational speed difference ΔN _IN . That is, the speed change outputs a shift control command signal (oil pressure command) S _T for changing the V groove widths of both variable pulleys 42 and 46 by controlling the flow rate of hydraulic fluid to the driving side hydraulic cylinder 42c to the hydraulic control circuit 100 The ratio γ is continuously changed.

The belt clamping pressure setting means 154, for example, from the belt clamping pressure map obtained and stored experimentally in advance as shown in FIG. 5, for example, the actual accelerator opening Acc and the actual input shaft rotational speed N by the electronic control unit 50. _The belt clamping pressure Pd ^* is set based on the vehicle state indicated by the actual speed ratio γ (= N _IN / N _OUT ) calculated based on _IN and the output shaft rotational speed N _OUT . That is, the belt clamping pressure setting means 154 sets the belt clamping pressure Pd of the output side hydraulic cylinder 46c for obtaining the belt clamping pressure Pd ^* .

Belt clamping pressure control means 156, the belt clamping pressure setting means 154 clamping pressure control command signal S _B for pressurizing regulates the belt clamping pressure Pd of the driven-side hydraulic cylinder 46c as set belt clamping pressure Pd ^* is obtained by Output to the hydraulic control circuit 100 to increase or decrease the belt clamping pressure Pd ^* .

The hydraulic control circuit 100, the supply of hydraulic fluid to the shift control command signal solenoid valve DS1 and operates the solenoid valve DS2 to the drive side hydraulic cylinder 42c so the shift of the continuously variable transmission 18 is executed in accordance with S _T · to control the emissions, by operating the linear solenoid valve SLS so that the belt clamping pressure Pd ^* is increased or decreased pressure of the belt clamping pressure Pd adjusted in accordance with the above clamping force control command signal S _B.

In addition to the above-described function, the shift control means 152 is provided with a gear ratio γ for eliminating the rotational speed difference ΔN _IN as a normal shift control on condition that the vehicle speed V is equal to or lower than the predetermined vehicle speed V ′. The feedback control is not performed, and the thrust ratio control valve 118 executes the closing control for maintaining the ratio between the transmission pressure Pin and the belt clamping pressure Pd in a predetermined relationship. That is, by closing the transmission ratio control valve UP114 and the transmission ratio control valve DN116, the operating oil is confined in the drive hydraulic cylinder 42c, and the transmission ratio γ of the continuously variable transmission 18 is set to a predetermined transmission ratio. A shift command (closed control command) signal S _T ′ for shifting control for low vehicle speed is output to the hydraulic control circuit 100 to establish a predetermined gear ratio.

The hydraulic control circuit 100 does not operate the solenoid valve DS1 and the solenoid valve DS2 so as to close the transmission ratio control valve UP114 and the transmission ratio control valve DN116 in accordance with the closing control command signal S _T ′, and controls the thrust ratio control. The valve 118 outputs a thrust ratio control hydraulic pressure _Pτ that maintains the ratio between the transmission pressure Pin and the belt clamping pressure Pd in a predetermined relationship.

In the continuously variable transmission 18 of the present embodiment, as described above, the gear ratio γ is set to the maximum gear ratio γmax during the closing control while the vehicle is stopped, that is, the transmission belt 48 is returned to the maximum deceleration position ( Hereinafter, it is referred to as a maximum deceleration state). Since the thrust ratio control oil pressure P _tau in the closed narrowing control is supplied to the drive side hydraulic cylinder 42c, it closed narrowing during vehicle launch after control with the rotation of the drive pulley 42 driving side hydraulic cylinder 42c in Upshifts may occur due to hydraulic oil that may remain in

Therefore, the shift control means 152 can execute normal shift control when the vehicle starts after the most deceleration determination means 158 determines (estimates) that the transmission belt 48 is in the lowest deceleration state and stops the vehicle. Prior to the normal shift control until the vehicle speed V exceeds the predetermined vehicle speed V ′, instead of the closing control, the transmission groove 48 is in the maximum deceleration state with the V groove width of the drive pulley 42 as the maximum width. Function as a start-time shift control means for outputting to the hydraulic control circuit 100 a duty down control command signal _ST "for duty down control that temporarily executes a downshift for discharging hydraulic oil from the drive side hydraulic cylinder 42c. Even when this duty-down control is executed and the hydraulic oil in the drive side hydraulic cylinder 42c is discharged, the transmission belt 48 is at its maximum when the vehicle is stopped. Never V groove width of the drive pulley 42 is increased when it is returned to the fast state.

The hydraulic control circuit 100 operates the solenoid valve DS1 and the solenoid valve DS2 in accordance with the duty down control command signal S _T ″ to discharge the hydraulic oil from the drive side hydraulic cylinder 42c. Thereby, the upshift of the continuously variable transmission 18 is performed. Is prevented and the gear ratio γ is maintained at the maximum gear ratio γmax.

  The most deceleration determination means 158 determines whether or not the speed ratio γ of the continuously variable transmission 18 is at the maximum speed ratio (minimum speed side speed ratio) γmax when the vehicle is controlled to be closed. For example, whether or not the vehicle has stopped in a state where the speed ratio γ is already at the maximum speed ratio γmax at the vehicle speed V exceeding the predetermined vehicle speed V ′ during vehicle deceleration traveling. Alternatively, the maximum speed ratio γmax that is estimated to be the maximum speed ratio γmax when the vehicle is stopped, although the speed ratio γ is not the maximum speed ratio γmax at the vehicle speed V that exceeds the predetermined vehicle speed V ′ during vehicle deceleration travel. Judgment is made based on whether or not there is a predetermined gear ratio γmax ′ in the vicinity and a downshift greater than or equal to a predetermined value.

  When it is determined by the most deceleration determination means 158 that the transmission belt 48 is in the most decelerated state, the belt return determination flag Fbelt is turned on by the electronic control unit 50, while the most deceleration determination means 158 causes the transmission belt 48 to be When it is determined that the vehicle is not in the deceleration state, the electronic control unit 50 turns off the belt return determination flag Fbelt.

The engine output control means 160 outputs an engine output control command signal S _E , for example, a throttle signal, an injection signal, an ignition timing signal, etc., to the throttle actuator 78, the fuel injection device 80, and the ignition device 82, respectively, for output control of the engine 12. To do. For example, the engine output control means 160 controls the engine torque T _E and outputs a throttle signal for opening and closing the electronic throttle valve 30 such that the throttle opening theta _TH corresponding to the accelerator opening Acc to the throttle actuator 78.

By the way, if the brakes are released and the vehicle slips in the direction opposite to the starting direction when the vehicle is re-started in the ascending direction after stopping on a steep uphill road (hereinafter referred to as a steep starting), Since the transmission torque capacity of the belt is lower at the time of positive rotation than that at the time of positive rotation, the belt clamping pressure Pd set by the belt clamping pressure setting means 154 is the same as in normal starting on a flat road. When ^* squeezing force control command signal S _B is output to the hydraulic control circuit 100 by the belt clamping pressure control means 156 so as to obtain, there is a possibility that the transmission torque capacity is caused to belt slip insufficient. At the time of re-start that is a steeply climbing slope where the road surface gradient exceeds a predetermined gradient, the belt clamping pressure Pd at this time may be set higher than the belt clamping pressure Pd ^* that is normally set to avoid the occurrence of belt slip. Conceivable.

However, when the hydraulic pressure is applied to the drive side hydraulic cylinder 42c as in the above-described closing control, the belt clamping pressure Pd is set higher than the normally set belt clamping pressure Pd ^* at the time of steep start. In some cases, the vehicle may not slide down, and if the belt clamping pressure Pd is increased uniformly, the transmission efficiency deteriorates, energy loss increases, and fuel consumption may deteriorate.

That is, it is necessary to increase the belt clamping pressure Pd in order to suppress the occurrence of belt slip at the time of steep start. The hydraulic oil in the drive side hydraulic cylinder 42c is discharged by the duty down control by the shift control means 152. as Rutoki, namely the thrust ratio control oil pressure P of the in closing control as predetermined hydraulic pressure acting on the driving side hydraulic cylinder 42c _tau is like when missing by the duty down control, to belt slippage This is only when the vehicle is in a severe vehicle condition, and it is possible that excessively increasing the belt clamping pressure Pd at the time of steep start will result in excessive oil pressure increase in an extra region.

Therefore, the belt clamping pressure control means 156 sets the belt clamping pressure Pd at this time as the normally set belt clamping pressure Pd ^* on the condition that the hydraulic pressure in the drive side hydraulic cylinder 42c is released at the time of steep start ^. It functions as a belt clamping pressure control means at the time of starting on an uphill road that is higher than that to avoid the occurrence of belt slip.

More specifically, the vehicle stop determination unit 162 determines whether or not the vehicle is in a stopped state, for example, whether or not the vehicle speed V (output shaft rotation speed N _OUT ) is equal to or less than a predetermined speed that is determined to be zero. Judgment based on.

  The steep slope determination means 164 determines whether or not the road surface slope on which the vehicle travels is an uphill road that exceeds a predetermined slope. For example, the steep slope determination means 164 is the absolute value of the longitudinal acceleration G detected by the acceleration sensor 76 that is one of road surface slope information when the vehicle stop determination means 162 determines that the vehicle is in a stopped state. Based on whether the value exceeds a predetermined value G ′, it is determined whether or not the road surface gradient is an uphill road exceeding the predetermined gradient. The predetermined value G ′ is experimental in advance for determining a steep slope that causes the vehicle to go backward when the foot brake, the parking brake, etc. are released for the operation of the accelerator pedal 68 when re-starting in the climbing direction. This is the determination value obtained.

The drive side hydraulic pressure drop determining means 166 at the start time determines whether or not the hydraulic pressure in the drive side hydraulic cylinder 42c is released when the vehicle starts. For example, the driving-time hydraulic pressure drop determining means 166 at the time of starting is based on whether or not duty down control is being executed by the speed change control means 152 when the vehicle starts, that is, the speed change control means 152 sets the duty down control command signal _ST. Based on whether or not “” is output to the hydraulic control circuit 100, it is determined whether or not the thrust ratio control hydraulic pressure P _τ in the drive side hydraulic cylinder 42c acting during the closing control is missing.

The belt clamping pressure control means 156 determines that the road slope is an uphill road with a road surface gradient exceeding a predetermined slope by the steep slope determination means 164 when the vehicle re-starts in the climbing direction, and the drive side hydraulic pressure drop determination means when starting. On the condition that the hydraulic pressure in the drive side hydraulic cylinder 42c is released by 166, the belt clamping pressure Pd at this time is changed to the normal belt clamping pressure Pd set by the belt clamping pressure setting means 154. ^{* A} higher value than ^* . This predetermined value corresponds to the correction hydraulic pressure value ΔP added to the belt clamping pressure Pd for obtaining the normal belt clamping pressure Pd ^* , and the temporary slip of the transmission belt 48 at the time of reverse rotation forward drive. In order to prevent this, it may be a constant value obtained experimentally in advance, or based on the actual road surface gradient from the relationship obtained experimentally in advance so that the predetermined value increases as the road surface gradient increases. It may be a calculated value.

  FIG. 8 is a flowchart for explaining a control operation of the electronic control device 50, that is, a control operation for improving the fuel consumption by increasing the belt clamping pressure Pd to a minimum, for example, about several msec to several tens msec. It is executed repeatedly with a very short cycle time.

First, in step S1 corresponding to the vehicle stop determination means 162 (hereinafter, step is omitted), it is determined whether the vehicle is in a stopped state, for example, the vehicle speed V (output shaft rotational speed N _OUT ) is zero. Judgment is made based on whether or not the predetermined speed is reached.

If the determination in S1 is affirmative, in S2 corresponding to the steep slope determination means 164, whether or not the road surface gradient on which the vehicle travels is an uphill road that exceeds a predetermined gradient is determined by, for example, an acceleration sensor when the vehicle is stopped. It is determined based on whether or not the absolute value of the longitudinal acceleration G detected by 76 exceeds a predetermined value G ′ (positive value). In other words, in S2, since the slope of the road surface on which the vehicle is stopped is determined when the vehicle re-starts in the ascending direction, the lever position P _SH is in the “D” position (range). If the longitudinal acceleration G, which is a positive value, exceeds a predetermined value G ′, which is a positive value, or if the lever position P _SH is in the “R” position (range), the longitudinal acceleration G, which is a negative value, is It is determined whether or not the negative value is smaller than a predetermined value G ′.

  If the determination in S2 is affirmative, in S3 corresponding to the most deceleration determination means 158, the speed ratio γ of the continuously variable transmission 18 is at the maximum speed ratio γmax when the vehicle is being controlled to be closed. Whether or not the transmission belt 48 is in the most decelerated state, for example, a state in which the speed ratio γ is already the maximum speed ratio γmax at a vehicle speed V that exceeds a predetermined vehicle speed V ′ during vehicle deceleration traveling. If the vehicle has stopped at the vehicle speed or the vehicle speed V exceeds the predetermined vehicle speed V ′ during vehicle deceleration, the gear ratio γ is not the maximum gear ratio γmax, but the vehicle is at a maximum gear ratio γmax when the vehicle is stopped. The determination is made based on whether or not the predetermined gear ratio γmax ′ is in the vicinity of the estimated maximum gear ratio γmax and the downshift is greater than or equal to a predetermined value.

If the determination in S3 is affirmative, the duty-down control command signal S _T ″ is temporarily set to the hydraulic control circuit 100 so that the transmission belt 48 is in the most decelerated state when the vehicle starts after the vehicle stops. is outputted to the in S4 that corresponds to the starting time of the drive side hydraulic leakage determination unit 166, when the vehicle is started, the thrust ratio control oil pressure P _tau escapes in the drive-side was acting in closing control hydraulic cylinder 42c Is determined based on whether or not the duty down control command signal S _T ″ is output to the hydraulic control circuit 100.

If the determination in S4 is affirmative, in S5 corresponding to the belt clamping pressure control means 156, when the vehicle restarts in the ascending direction, the belt clamping pressure Pd at this time is, for example, as shown in FIG. It is made higher by a predetermined value than the normal belt clamping pressure Pd ^* set based on the actual accelerator opening Acc and the actual gear ratio γ from the pressure map.

If the determination of any of S1, S2, S3, and S4 is negative, in S6 corresponding to the belt clamping pressure control means 156, the belt clamping pressure Pd at this time is the normal belt clamping pressure Pd. without being higher than ^*, its normal belt clamping pressure Pd ^* is squeezing force control command signal S _B so obtained is output to the hydraulic control circuit 100.

As described above, according to the present embodiment, when the vehicle restarts in the ascending direction, the steep slope determination means 164 determines that the road surface gradient on which the vehicle travels is an uphill road that exceeds a predetermined slope, and is driven at the time of start. On the condition that the hydraulic pressure in the drive side hydraulic cylinder 42c is determined to be released by the side hydraulic pressure release determining means 166, the belt clamping pressure control means 156 determines that the belt clamping pressure Pd at this time is the belt clamping pressure setting means 154. Is set to a predetermined value higher than the normal belt clamping pressure Pd ^* set by the belt, so that the belt is only in a state where the oil pressure in the drive side hydraulic cylinder 42c is released and the belt is likely to slip when the vehicle starts to climb. The pinching pressure Pd is increased, and an increase in the belt pinching pressure Pd is minimized, so that fuel efficiency can be improved.

Further, according to the present embodiment, when the vehicle starts, the thrust ratio in the drive side hydraulic cylinder 42c acting during the closing control is determined based on whether or not the duty reduction control is executed by the shift control means 152. Whether or not the control hydraulic pressure _Pτ is lost is determined by the driving-side hydraulic pressure drop determining means 166 at the start, so that the hydraulic oil is confined in the drive-side hydraulic cylinder 42c in the vehicle state below the predetermined vehicle speed V ′. In order to prevent an upshift from occurring due to the thrust ratio control hydraulic pressure P _{τ applied} to the drive side hydraulic cylinder 42c at the time of starting, the transmission ratio γ of the continuously variable transmission 18 is set by the transmission control means 152. The belt clamping pressure Pd is increased only when the downshift is temporarily executed so as to obtain the maximum gear ratio γmax, and belt slippage is avoided. The increase of the belt clamping pressure Pd it is possible to improve the fuel consumption as a minimum with.

  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 steep slope determining unit 164 determines whether or not the road surface gradient is an uphill road where the road surface gradient exceeds a predetermined gradient based on the longitudinal acceleration G detected by the acceleration sensor 76. The uphill road may be determined without being based on. For example, the road surface gradient may be determined by comparing the reference acceleration and the actual acceleration. If the road surface gradient is included in the road information stored in a well-known navigation device, the road surface gradient is determined. The current road surface gradient may be determined based on the travel position information from the information.

  Further, in the above-described embodiment, the hydraulic pressure in the drive side hydraulic cylinder 42c is reduced in order to avoid an upshift caused by the hydraulic oil remaining in the drive side hydraulic cylinder 42c due to the closing control at the time of steep start. Even when the belt clamping pressure Pd is increased when the pulling operation is executed, but the control device for the continuously variable transmission does not execute the closing control, the drive side is set so that the speed ratio γ becomes the maximum speed ratio γmax. The present invention can be applied to the case where the operation of releasing the hydraulic pressure in the hydraulic cylinder 42c is executed.

In the above-described embodiment, the input shaft rotational speed N _IN exemplified as the rotational speed of the predetermined rotating member and the target input shaft rotational speed N _IN ^* related thereto are replaced with the input shaft rotational speed N _{IN and the} like. The engine rotational speed _NE and the related target engine rotational speed _NE ^* may be used, or the turbine rotational speed _NT and the related target turbine rotational speed _NT ^* may be used. Accordingly, a rotational speed sensor such as the input shaft rotational speed sensor 56 may be appropriately provided in accordance with the rotational speed that needs to be controlled.

  In the above-described embodiment, the torque converter 14 provided with the lock-up clutch 26 is used as the fluid transmission device. However, the lock-up clutch 26 is not necessarily provided. In addition, other fluid type power transmission devices such as a fluid coupling (fluid coupling) having no torque amplification function may 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.

1 is a skeleton diagram illustrating a vehicle drive device to which the present invention is applied. It is a block diagram explaining the principal part of the control system provided in the vehicle in order to control the vehicle drive device etc. of FIG. FIG. 4 is a main part hydraulic circuit diagram showing a part related to belt clamping pressure control of a continuously variable transmission, gear ratio control, and engagement hydraulic control of a forward clutch or a reverse brake accompanying operation of a shift lever in the hydraulic control circuit. It is a figure which shows an example of the shift map used when calculating | requiring a target input rotational speed in the shift control of a continuously variable transmission. It is a figure which shows an example of the required hydraulic pressure map which calculates | requires required hydraulic pressure according to gear ratio etc. in the clamping pressure control of a continuously variable transmission. This is a relationship obtained and stored in advance between the gear ratio and the thrust ratio with the vehicle speed as a parameter. It is a functional block diagram explaining the principal part of the control function of the electronic control apparatus of FIG. 3 is a flowchart for explaining a control operation of the electronic control device of FIG. 2, that is, a control operation for improving fuel consumption by increasing the belt clamping pressure to a minimum.

Explanation of symbols

12: Engine (power source for running)
18: continuously variable transmission 24: driving wheel 42: driving pulley 42c: driving hydraulic cylinder (driving hydraulic actuator)
46: driven pulley 46c: driven hydraulic cylinder (driven hydraulic actuator)
48: Transmission belt (belt)
50: Electronic control device (control device)
152: Shift control means (startup shift control means)
156: Belt clamping pressure control means (belt clamping pressure control means when starting uphill road)
158: Maximum deceleration determination means 164: Steep slope determination means 166: Drive side hydraulic pressure dropout determination means at start

Claims (2)

In a vehicle in which a continuously variable transmission having a driving pulley and a driven pulley and a belt wound around both pulleys is disposed on a power transmission path between a driving power source and driving wheels, the driving side A drive-side hydraulic actuator for changing the groove width of the pulley and a driven-side hydraulic actuator for changing the groove width of the driven-side pulley, and performing a shift by supplying and discharging hydraulic oil to and from the drive-side hydraulic actuator; A control device for a continuously variable transmission for a vehicle that controls a belt clamping pressure by the driven hydraulic actuator so that no slip occurs between the belt and both pulleys,
Steep slope determination means for determining whether or not the road surface gradient on which the vehicle travels is a slope that exceeds a predetermined gradient;
When starting the vehicle, the driving-side hydraulic pressure drop-off determining means for determining whether or not the hydraulic pressure in the driving-side hydraulic actuator is low;
When starting the vehicle in the ascending direction, it is determined by the steep slope determination means that the road exceeds a predetermined slope, and it is determined that the hydraulic pressure in the drive side hydraulic actuator has been released by the drive side hydraulic pressure drop determination means when starting. And a belt clamping pressure control means at the time of starting uphill road that makes the belt clamping pressure at this time higher than a normal belt clamping pressure set from a relationship stored in advance. A control device for a continuously variable transmission for a vehicle. The control device sets a transmission gear ratio of the continuously variable transmission to a predetermined value in a state where a predetermined hydraulic pressure is applied to the driving hydraulic actuator and the working oil is confined in the driving hydraulic actuator in a vehicle state of a predetermined vehicle speed or less. A gear ratio,
A minimum deceleration determination means for determining whether or not the speed ratio of the continuously variable transmission is at the minimum speed side gear ratio when the vehicle is stopped;
On the condition that the speed ratio of the continuously variable transmission is determined to be the lowest speed side gear ratio by the most deceleration determination means, the speed ratio of the continuously variable transmission is the lowest speed side speed ratio when starting the vehicle. And a start shift control means for temporarily executing a down shift operation for discharging hydraulic oil from the drive side hydraulic actuator so that
The starting drive side hydraulic pressure drop determining means determines whether or not the hydraulic pressure in the driving side hydraulic actuator is released based on whether or not the downshift operation is being executed by the starting shift control means. The control device for a continuously variable transmission for a vehicle according to claim 1.

Images