JP2010007834A - Control device and control method for continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve both suppression of belt slip during gear shift and suppression of reduction in shifting speed without complicating the structure of a continuously variable transmission in a belt-type continuously variable transmission. <P>SOLUTION: An ECU determines whether or not the hydraulic fluid temperature T (C) of the belt-type continuously variable transmission is lower than a threshold (S106) when a vehicle is braked (YES in S102) and is in sudden braking (YES in S104), estimates that there is possibility of an air suction condition when the hydraulic fluid temperature T (C) is lower than the threshold (YES in S106), and sets a target gear ratio to a constant value γ(1) until a predetermined time T elapses from start of gear shift (NO in S108, S110). After lapse of the predetermined time T, the target gear ratio is set to a gear ratio γmax on the most speed reduced side (S112). The constant value γ(1) is set to γ(0)<γ(1)<γmax where γ(0) presents the gear ratio when starting downshifting. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to control of a continuously variable transmission, and more particularly to shift control of a belt type continuously variable transmission.

  A belt type continuously variable transmission for a vehicle has two rotating members arranged in parallel, and a primary pulley and a secondary pulley separately attached to each rotating member. Both the primary pulley and the secondary pulley are configured by combining a fixed sheave and a movable sheave, and a V-shaped groove is formed between the fixed sheave and the movable sheave. Furthermore, a belt is wound around the groove of the primary pulley and the groove of the secondary pulley, and hydraulic cylinders that adjust the groove width of the pulley by moving the movable sheave of the primary pulley are separately provided on the primary pulley side and the secondary pulley side. Is provided.

  The primary pulley side hydraulic cylinder (hereinafter also referred to as “primary hydraulic chamber”) is controlled to change the gear ratio by controlling the groove width of the primary pulley, while the secondary pulley side hydraulic cylinder (hereinafter referred to as “primary hydraulic chamber”). The clamping pressure of the belt is controlled by controlling the hydraulic pressure in the “secondary hydraulic chamber”.

  For example, when downshifting (that is, when increasing the gear ratio), the hydraulic oil in the primary hydraulic chamber is discharged and the movable sheave on the primary side is moved in the direction of widening the groove width of the primary pulley. At this time, in order to maintain a sufficient belt clamping pressure, hydraulic oil is supplied to the secondary hydraulic chamber in accordance with the movement of the primary movable sheave to narrow the groove width of the secondary pulley in the secondary movable sheave. Need to move in the direction. Therefore, at the time of a sudden downshift, it is necessary to supply a large amount of hydraulic oil to the secondary hydraulic chamber in a short time and to quickly move the movable sheave on the secondary side. Japanese Patent Laying-Open No. 2005-299803 (Patent Document 1) discloses a technique capable of quickly moving a primary movable sheave and a secondary movable sheave during a sudden downshift.

  A hydraulic control device disclosed in Japanese Patent Laying-Open No. 2005-299803 includes at least one shift control hydraulic chamber for changing a groove width of a primary pulley and a tension control belt acting on a secondary movable sheave. The hydraulic pressure of a belt-type continuously variable transmission including two hydraulic chambers that generate a clamping pressure is controlled. The control device discharges hydraulic oil from an outer diameter side hydraulic chamber of two secondary hydraulic chambers (an outer diameter side hydraulic chamber and an inner diameter side hydraulic chamber) under a predetermined operating condition, During a sudden downshift under operating conditions, hydraulic fluid is supplied from the primary-side shift control hydraulic chamber to the secondary-side outer-diameter hydraulic chamber.

According to the hydraulic control device disclosed in Japanese Patent Application Laid-Open No. 2005-299803, a large amount of hydraulic oil is transferred from the primary-side shift control hydraulic chamber to the secondary-side outer-diameter hydraulic chamber during a sudden downshift under predetermined operating conditions. Promptly supplied. Therefore, the movable sheave on the primary side and the secondary side can be quickly moved, and the centrifugal hydraulic pressure is generated in the outer diameter side hydraulic chamber on the secondary side and the force to move the movable sheave increases. Can be moved quickly.
JP 2005-299803 A Japanese Patent Laid-Open No. 5-118424

  However, in order to apply the hydraulic control device disclosed in Japanese Patent Laid-Open No. 2005-299803, it is necessary to provide two hydraulic chambers (an outer diameter side hydraulic chamber and an inner diameter side hydraulic chamber) on the secondary side of the continuously variable transmission. Therefore, the structure of the continuously variable transmission becomes complicated.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a belt-type continuously variable transmission that is capable of slipping a belt during shifting without complicating the structure of the continuously variable transmission. It is an object of the present invention to provide a control device and a control method capable of satisfying both the suppression of the shift and the decrease of the shift speed.

  A control device according to a first aspect of the present invention controls a belt-type continuously variable transmission that is provided between a drive source and drive wheels and continuously changes a gear ratio using oil output from an oil pump. . This control device includes a predicting unit for predicting whether or not the oil flow rate output from the oil pump is less than an oil amount necessary for shift control of the continuously variable transmission, and the oil flow rate by the predicting unit. If it is predicted that there will be a shortage, the shift control is delayed in the first period from the start of the shift until the predetermined time elapses, compared to the case where the oil flow rate is not predicted to be insufficient, and the shift is completed after the first period has elapsed. Control means for controlling the continuously variable transmission so that the shift control proceeds more rapidly than in the first period in the second period until.

  In the control device according to the second invention, in addition to the configuration of the first invention, the control means changes the speed ratio of the continuously variable transmission from the value at the start of the shift to the value at the completion of the shift. In the first period, the transmission ratio is maintained at a constant value between the value at the start of the shift and the value at the completion of the shift, and in the second period, the transmission ratio is changed from a constant value to a value at the completion of the shift.

In the control device according to the third aspect of the invention, in addition to the configuration of the first aspect of the invention, when the control means changes the speed ratio of the continuously variable transmission, the control means changes the speed ratio to the first change speed during the first period. And changing the gear ratio at a second change speed larger than the first change speed in the second period from the elapse of the first period to the completion of the shift,
In the control device according to the fourth invention, in addition to the configuration of the first invention, the continuously variable transmission includes a pair of pulleys around which a belt is wound and a groove width of one pulley is changed. Using the first hydraulic cylinder that changes the transmission ratio of the step transmission, the second hydraulic cylinder that changes the belt clamping pressure by changing the groove width of the other pulley, and the oil output from the oil pump A first pressure regulating valve that adjusts the amount of oil in the first hydraulic cylinder and a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder using oil output from the oil pump are provided. The predicting means predicts whether or not the flow rate of the oil is less than the amount of oil necessary for suppressing belt slip when the continuously variable transmission is downshifted. When the control means predicts that the flow rate of the oil is insufficient by the predicting means when performing the downshift of the continuously variable transmission by widening the groove width of the first pulley, the first hydraulic cylinder in the first period The oil amount of the first hydraulic cylinder is reduced to a constant value between the value at the start of downshift and the value at the completion of downshift, and the oil amount of the first hydraulic cylinder is changed from the constant value to the value at the time of completion of shifting in the second period. The first pressure regulating valve is controlled to decrease to a value.

  In the control device according to the fifth invention, in addition to the configuration of the first invention, the continuously variable transmission includes a first pulley connected to the drive source and a second pulley connected to the drive wheel. A belt wound around the first pulley and the second pulley, a first hydraulic cylinder that changes a gear ratio of the continuously variable transmission by changing a groove width of the first pulley, and a second hydraulic cylinder A second hydraulic cylinder for changing the belt clamping pressure by changing the pulley groove width, and a first pressure regulating valve for adjusting the amount of oil in the first hydraulic cylinder using oil output from the oil pump; And a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder using oil output from the oil pump. The predicting means predicts whether or not the oil output amount is less than the oil amount necessary for suppressing belt slip when the continuously variable transmission is downshifted. When the predicting means predicts that the oil output amount is insufficient when the continuously variable transmission is downshifted by widening the groove width of the first pulley, the control means is configured to output the first hydraulic cylinder in the first period. Of the first hydraulic cylinder is discharged at a first discharge speed, and in the second period, the oil amount of the first hydraulic cylinder is discharged at a second discharge speed larger than the first discharge speed. Control the pressure valve.

  In the control device according to the sixth invention, in addition to the configuration of any one of the first to fifth inventions, the first period is longer than the second period.

  The control device according to a seventh aspect of the invention further includes a deceleration rate calculation means for calculating the deceleration rate of the vehicle in addition to the configuration of any one of the first to sixth aspects of the invention. The predicting unit predicts that the oil flow rate is insufficient when the deceleration rate calculated by the deceleration rate calculating unit is larger than the threshold value.

  The control device according to the eighth aspect of the invention further includes an oil temperature detecting means for detecting the temperature of the oil in addition to the configuration of any one of the first to sixth aspects of the invention. The predicting means predicts that the oil flow rate is insufficient when the temperature detected by the oil temperature detecting means exceeds the threshold value.

  In the control device according to the ninth invention, in addition to the configuration of any one of the first to sixth inventions, the predicting means estimates whether or not the oil pump is in an air sucking state in which air is sucked, When it is estimated that the air is sucked, the oil flow rate is predicted to be insufficient.

  A control device according to a tenth aspect of the invention further includes a flow rate detecting means for detecting the flow rate of oil in addition to the configuration of the ninth aspect of the invention. The predicting means estimates that the air is sucked when the flow rate of the oil detected by the flow rate detecting means is smaller than the threshold value.

  The control methods according to the 11th to 20th inventions have the same requirements as the control devices according to the 1st to 10th inventions, respectively.

  According to the present invention, when shifting the continuously variable transmission, if it is predicted that the flow rate of the oil output from the oil pump will be less than the amount of oil required for the shift control, a predetermined time has elapsed since the start of the shift. Since the progress of the shift control is delayed in the first period until the start, oil shortage due to the sudden shift is eliminated, and belt slip can be suppressed. Further, since the shift control proceeds more rapidly in the second period after the first period than in the first period, a decrease in the overall shift speed is suppressed. Therefore, it is possible to achieve both suppression of belt slip at the time of shifting and suppression of decrease in the shifting speed without complicating the structure of the continuously variable transmission.

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

  A vehicle equipped with a control device according to the present embodiment will be described with reference to FIG. The output of the engine 200 of the drive device 100 mounted on the vehicle is input to the belt-type continuously variable transmission 500 via the torque converter 300 and the forward / reverse switching device 400. The output of the continuously variable transmission 500 is transmitted to the reduction gear 600 and the differential gear device 700, and is distributed to the left and right drive wheels 800. The driving device 100 is controlled by an ECU (Electronic Control Unit) 8000 described later. The control device according to the present embodiment is realized by a program executed by ECU 8000, for example.

  The torque converter 300 includes a pump impeller 302 connected to the crankshaft of the engine 200 and a turbine impeller 306 connected to the forward / reverse switching device 400 via the turbine shaft 304. A lockup clutch 308 is provided between the pump impeller 302 and the turbine impeller 306. The lockup clutch 308 is engaged or released when the hydraulic pressure supply to the engagement side oil chamber and the release side oil chamber is switched. When the lockup clutch 308 is completely engaged, the pump impeller 302 and the turbine impeller 306 are integrally rotated.

  The pump impeller 302 is provided with a mechanical oil pump 310 that generates hydraulic pressure for controlling the transmission of the continuously variable transmission 500, generating a belt clamping pressure, and supplying lubricating oil to each part. ing.

  The oil pump 310 is driven by the rotation of the crankshaft of the engine 200 and sucks oil stored in the oil pan 314 (see FIG. 3) from the suction port of the strainer 312 (see FIG. 3). Output. The oil output from the oil pump 310 is supplied to the hydraulic control circuit 2000 (see FIG. 2) as hydraulic oil for the forward / reverse switching device 400 and the continuously variable transmission 500.

  The forward / reverse switching device 400 is composed of a double pinion type planetary gear device. Turbine shaft 304 of torque converter 300 is connected to sun gear 402. The input shaft 502 of the continuously variable transmission 500 is connected to the carrier 404. Carrier 404 and sun gear 402 are connected via forward clutch 406. The ring gear 408 is fixed to the housing via the reverse brake 410. The forward clutch 406 and the reverse brake 410 are frictionally engaged by a hydraulic cylinder.

  When the forward clutch 406 is engaged and the reverse brake 410 is released, the forward / reverse switching device 400 enters the forward engagement state. In this state, the driving force in the forward direction is transmitted to the continuously variable transmission 500. When the reverse brake 410 is engaged and the forward clutch 406 is released, the forward / reverse switching device 400 enters the reverse engagement state. In this state, the input shaft 502 is rotated in the reverse direction with respect to the turbine shaft 304. As a result, the driving force in the reverse direction is transmitted to the continuously variable transmission 500. When both forward clutch 406 and reverse brake 410 are released, forward / reverse switching device 400 enters a neutral state in which power transmission is interrupted.

  The continuously variable transmission 500 includes a primary pulley 510 provided on the input shaft 502, a secondary pulley 520 provided on the output shaft 506, and a transmission belt 530 wound around these pulleys. Power transmission is performed using frictional forces between the pulleys 510 and 520 and the transmission belt 530.

  Primary pulley 510 includes a fixed sheave 512, a movable sheave 514, and a primary hydraulic chamber (primary hydraulic cylinder) 516. The primary hydraulic chamber 516 moves the movable sheave 514 in a direction along the axial direction of the input shaft 502 in accordance with a change in internal hydraulic pressure (oil amount). As a result, the groove width of the primary pulley 510 changes, and the groove width of the secondary pulley 520 also changes due to the action of a return spring (not shown) provided in the secondary pulley 520. Therefore, the engagement diameter of the transmission belt 530 is changed, and the actual gear ratio (= primary pulley rotation speed NIN / secondary pulley rotation speed NOUT) γ is continuously changed.

  Secondary pulley 520 includes a fixed sheave 522, a movable sheave 524, and a secondary hydraulic chamber (secondary hydraulic cylinder) 526. The secondary hydraulic chamber 526 moves the movable sheave 524 in a direction along the axial direction of the output shaft 506 in accordance with a change in internal hydraulic pressure (oil amount). Thereby, the belt clamping pressure is controlled.

  As shown in FIG. 2, the ECU 8000 includes an engine speed sensor 902, a turbine speed sensor 904, a vehicle speed sensor 906, a throttle opening sensor 908, a cooling water temperature sensor 910, an oil temperature sensor 912, an accelerator opening sensor 914, a pedal effort. A sensor 916, a position sensor 918, a primary pulley rotation speed sensor 922, a secondary pulley rotation speed sensor 924, a G sensor 926, and a flow rate sensor 928 are connected.

  The engine speed sensor 902 detects the engine speed (engine speed) NE of the engine 200. The turbine rotation speed sensor 904 detects the rotation speed (turbine rotation speed) NT of the turbine shaft 304. The vehicle speed sensor 906 detects the vehicle speed V. The throttle opening sensor 908 detects the opening degree θ (TH) of the electronic throttle valve. Cooling water temperature sensor 910 detects cooling water temperature T (W) of engine 200. The oil temperature sensor 912 detects the oil temperature T (C) of the continuously variable transmission 500 or the like. The accelerator opening sensor 914 detects an accelerator pedal opening (accelerator opening) A (CC). The pedaling force sensor 916 detects the pedaling force of the brake pedal (force that the driver steps on the brake pedal) SF. The position sensor 918 detects the position P (SH) of the shift lever 920 by determining whether the contact provided at the position corresponding to the shift position is ON or OFF. Primary pulley rotation speed sensor 922 detects rotation speed NIN of primary pulley 510. Secondary pulley rotation speed sensor 924 detects rotation speed NOUT of secondary pulley 520. The G sensor 926 detects the acceleration α in the vehicle longitudinal direction. The flow sensor 928 detects the flow rate of oil output from the oil pump 310 (that is, the flow rate of oil sucked from the suction port of the strainer 312) FL. A signal representing the detection result of each sensor is transmitted to ECU 8000.

  ECU 8000 executes output control of engine 200, shift control of continuously variable transmission 500, belt clamping pressure control, forward clutch 406 engagement / release control, reverse brake 410 engagement / release control, and the like.

  Output control of the engine 200 is performed by an electronic throttle valve 1000, a fuel injection device 1100, an ignition device 1200, and the like. The hydraulic control circuit 2000 performs the shift control of the continuously variable transmission 500, the belt clamping pressure control, the engagement / release control of the forward clutch 406, and the engagement / release control of the reverse brake 410.

  The hydraulic control circuit 2000 will be described with reference to FIGS. The hydraulic control circuit 2000 described below is an example, and the present invention is not limited to this.

  As shown in FIG. 3, the oil output from the oil pump 310 (hydraulic pressure generated by the oil pump 310) passes through the line pressure oil path 2002 to the primary regulator valve 2100, the modulator valve (1) 2310, and the modulator valve ( 3) supplied to 2330

  The primary regulator valve 2100 is selectively supplied with control pressure from one of an SLT linear solenoid valve (hereinafter referred to as “SLT”) 2200 and an SLS linear solenoid valve (hereinafter referred to as “SLS”) 2210. .

  SLT2200 and SLS2210 are normally open (the hydraulic pressure output when no power is supplied) type solenoid valves.

  The spool of the primary regulator valve 2100 slides up and down according to the supplied control pressure. As a result, the hydraulic pressure generated by the oil pump 310 is regulated (adjusted) by the primary regulator valve 2100. The hydraulic pressure adjusted by primary regulator valve 2100 is used as line pressure PL. In the present embodiment, the higher the control pressure supplied to primary regulator valve 2100, the higher the line pressure PL. Note that the higher the control pressure supplied to the primary regulator valve 2100, the lower the line pressure PL may be.

  The SLT 2200 and the SLS 2210 are supplied with hydraulic pressure regulated by the modulator valve (3) 2330 using the line pressure PL as a source pressure.

  SLT 2200 and SLS 2210 output a hydraulic pressure (control pressure) corresponding to a current value determined by a duty signal (duty ratio) transmitted from ECU 8000.

  Of the control pressure (output hydraulic pressure) of SLT 2200 and the control pressure (output hydraulic pressure) of SLS 2210, the control pressure supplied to primary regulator valve 2100 is selected by control valve 2400.

  When the spool of the control valve 2400 is in the state (A) in FIG. 3 (left side state), the control pressure is supplied from the SLT 2200 to the primary regulator valve 2100. That is, the line pressure PL is controlled according to the control pressure of the SLT 2200.

  When the spool of the control valve 2400 is in the state (B) in FIG. 3 (right state), the control pressure is supplied from the SLS 2210 to the primary regulator valve 2100. That is, the line pressure PL is controlled according to the control pressure of the SLS 2210.

  When the spool of the control valve 2400 is in the state of (B) in FIG. 3, the control pressure of the SLT 2200 is supplied to a manual valve 2600 described later.

  The spool of the control valve 2400 is urged in one direction by a spring. The shift control duty solenoid (1) (hereinafter referred to as “DS (1)”) 2510 and the shift control duty solenoid (2) (hereinafter referred to as “DS (2)”) are arranged so as to oppose the urging force of the spring. The hydraulic pressure is supplied from 2520 (described below).

  DS (1) 2510 and DS (2) 2520 are normally closed solenoid valves. DS (1) 2510 and DS (2) 2520 output hydraulic pressure (control pressure) corresponding to a current value determined by duty signals S1 (duty ratio D1) and S2 (duty ratio D2) transmitted from ECU 8000.

  When hydraulic pressure is supplied to the control valve 2400 from both DS (1) 2510 and DS (2) 2520, the spool of the control valve 2400 is in the state of (B) in FIG.

  When the hydraulic pressure is not supplied from at least one of DS (1) 2510 and DS (2) 2520 to the control valve 2400, the spool of the control valve 2400 is brought into the state of (A) in FIG. 3 by the biasing force of the spring. Become.

  DS (1) 2510 and DS (2) 2520 are supplied with hydraulic pressure regulated by the modulator valve (4) 2340. The modulator valve (4) 2340 regulates the hydraulic pressure supplied from the modulator valve (3) 2330 to a constant pressure.

  A line pressure PL controlled by the control pressure of the SLT 2200 or SLS 2210 is introduced into the modulator valve (1) 2310.

  The modulator valve (1) 2310 regulates the introduced line pressure PL using the output hydraulic pressure of the SLS 2210 as a pilot pressure, and supplies it to the secondary hydraulic chamber 526. The belt clamping pressure is increased or decreased according to the output hydraulic pressure from the modulator valve (1) 2310.

  The ECU 8000 uses the accelerator opening A (CC), the actual gear ratio γ, or the target gear ratio (target value of the actual gear ratio γ) as a parameter to set the duty ratio of the SLS 2210 so that the belt clamping pressure does not cause belt slip ( The output hydraulic pressure of the SLS 2210 is controlled.

  The hydraulic pressure supplied to the secondary hydraulic chamber 526 is detected by the pressure sensor 2312.

  The manual valve 2600 will be described with reference to FIG. Manual valve 2600 is mechanically switched according to the operation of shift lever 920. Thereby, the forward clutch 406 and the reverse brake 410 are engaged or released.

  Shift lever 920 is operated to a “P” position for parking, an “R” position for reverse travel, an “N” position for interrupting power transmission, a “D” position and “B” position for forward travel.

  In the “P” position and the “N” position, the hydraulic pressure in the forward clutch 406 and the reverse brake 410 is drained from the manual valve 2600. Thereby, the forward clutch 406 and the reverse brake 410 are released.

  In the “R” position, hydraulic pressure is supplied from the manual valve 2600 to the reverse brake 410. Thereby, the reverse brake 410 is engaged. On the other hand, the hydraulic pressure in forward clutch 406 is drained from manual valve 2600. As a result, the forward clutch 406 is released.

  When the control valve 2400 is in the state (A) in FIG. 4 (left side state), the modulator pressure PM supplied from the modulator valve (2) (not shown) is supplied to the manual valve 2600 via the control valve 2400. The The reverse brake 410 is held in the engaged state by the modulator pressure PM.

  When the control valve 2400 is in the state (B) in FIG. 4 (right side state), the hydraulic pressure regulated by the SLT 2200 is supplied to the manual valve 2600. By adjusting the hydraulic pressure by the SLT 2200, the reverse brake 410 is gently engaged, and a shock at the time of engagement is suppressed.

  Further, when the control valve 2400 is in the state (B) in FIG. 4 (right side state), if the duty ratio of the SLT 2200 is set to 100% and the energization amount is maximized, the hydraulic pressure is not output from the SLT 2200, and the reverse brake The hydraulic pressure supplied to 410 becomes “0”. That is, the hydraulic pressure is drained from the reverse brake 410 via the SLT 2200, and the reverse brake 410 is released.

  In the “D” position and the “B” position, hydraulic pressure is supplied from the manual valve 2600 to the forward clutch 406. As a result, the forward clutch 406 is engaged. On the other hand, the hydraulic pressure in the reverse brake 410 is drained from the manual valve 2600. Thereby, the reverse brake 410 is released.

  When the control valve 2400 is in the state (A) in FIG. 4 (left side state), the modulator pressure PM supplied from the modulator valve (2) (not shown) is supplied to the manual valve 2600 via the control valve 2400. The The forward clutch 406 is held in the engaged state by the modulator pressure PM.

  When the control valve 2400 is in the state (B) in FIG. 4 (right side state), the hydraulic pressure regulated by the SLT 2200 is supplied to the manual valve 2600. By adjusting the hydraulic pressure by the SLT 2200, the forward clutch 406 is gently engaged, and a shock at the time of engagement is suppressed.

  With reference to FIG. 5, a configuration for performing the shift control will be described. Shift control is performed by controlling the supply and discharge of hydraulic pressure to the primary hydraulic chamber 516. Supply and discharge of hydraulic oil to and from the primary hydraulic chamber 516 are performed using a ratio control valve (1) 2710 and a ratio control valve (2) 2720.

  The primary hydraulic chamber 516 is in communication with a ratio control valve (1) 2710 to which the line pressure PL is supplied and a ratio control valve (2) 2720 connected to the drain.

  The ratio control valve (1) 2710 is a valve for executing an upshift. The ratio control valve (1) 2710 is configured to open and close the flow path between the input port to which the line pressure PL is supplied and the output port connected to the primary hydraulic chamber 516 with a spool.

  A spring is disposed at one end of the spool of the ratio control valve (1) 2710. A port to which a control pressure from DS (1) 2510 is supplied is formed at the end opposite to the spring across the spool. In addition, a port to which a control pressure from DS (2) 2520 is supplied is formed at the end on the side where the spring is disposed.

  When DS (1) 2510 is turned on and DS (2) 2520 is turned off, the spool of the ratio control valve (1) 2710 is in the state (D) in FIG.

  In this state, the hydraulic pressure supplied to the primary hydraulic chamber 516 increases and the groove width of the primary pulley 510 becomes narrow. As a result, the actual gear ratio γ decreases. That is, an upshift is performed.

  The ratio control valve (2) 2720 is a valve for executing a downshift. A spring is disposed at one end of the spool of the ratio control valve (2) 2720. A port to which a control pressure from DS (1) 2510 is supplied is formed at the end on the side where the spring is disposed. A port to which a control pressure from DS (2) 2520 is supplied is formed at the end opposite to the spring across the spool.

  When DS (1) 2510 is turned off (DS (1) 2510 duty ratio D1 = 0%) and DS (2) 2520 is turned on (DS (2) 2520 duty ratio D2> 0%), the ratio control valve (2) The spool 2720 is in the state (C) (left side state) in FIG. At the same time, the spool of the ratio control valve (1) 2710 is in the state (C) (left side state) in FIG.

  In this state, hydraulic fluid is discharged from the primary hydraulic chamber 516 via the ratio control valve (1) 2710 and the ratio control valve (2) 2720. Therefore, the groove width of the primary pulley 510 is increased. As a result, the actual gear ratio γ increases. That is, downshift. Further, as the duty ratio D2 of the DS (2) 2520 is increased, the hydraulic oil discharge flow rate (discharge speed) from the primary hydraulic chamber 516 is increased, and the shift speed is increased.

  With reference to FIG. 6, a control structure of a program executed when ECU 8000 serving as the control device according to the present embodiment performs the shift control of continuously variable transmission 500 will be described. Note that this program is repeatedly executed at a predetermined cycle time.

  In step (hereinafter step is abbreviated as S) 100, ECU 8000 calculates a target gear ratio. At this time, when braking the vehicle, ECU 8000 calculates the target gear ratio so as to be the speed ratio γmax on the most deceleration side before the vehicle stops in order to ensure the start performance after the vehicle stops. Details of this process will be described later.

  In S200, ECU 8000 controls the hydraulic pressure in primary hydraulic chamber 516 (hereinafter also referred to as “primary pressure”) based on the calculated target gear ratio. For example, when downshifting by increasing the target gear ratio, ECU 8000 sets the duty ratio D1 of DS (1) 2510 to 0% and increases the duty ratio D2 of DS (2) 2520 according to the target gear ratio. The hydraulic oil is discharged from the primary hydraulic chamber 516. As a result, the movable sheave 514 on the primary side moves in the direction of widening the groove width of the primary pulley 510, and the actual gear ratio γ is increased to the target gear ratio.

  In S300, ECU 8000 controls the hydraulic pressure in secondary hydraulic chamber 526 (hereinafter also referred to as “secondary pressure”) in accordance with the calculated target gear ratio. For example, when the ECU 8000 increases the target speed ratio and performs a downshift, the duty ratio of the SLS 2210 is increased in accordance with the increase of the target speed ratio (that is, movement of the movable sheave 514 on the primary side), and the secondary hydraulic chamber 526 is increased. Supply hydraulic oil to Thereby, the movable sheave 524 on the secondary side moves in the direction of narrowing the groove width of the secondary pulley 520, and a decrease in the clamping pressure of the belt is suppressed.

  As described above, ECU 8000 discharges the hydraulic oil in primary hydraulic chamber 516 when performing a downshift (S200). At this time, in order to suppress a decrease in belt clamping pressure, hydraulic oil is supplied to the secondary hydraulic chamber 526, and the secondary movable sheave 524 is moved in accordance with the movement of the primary movable sheave 514 (S300).

  At the time of braking of the vehicle, as described above, the ECU 8000 increases the target gear ratio to γmax before the vehicle stops in order to ensure the starting performance after the vehicle stops (S10). Therefore, at the time of sudden braking in which the time until the vehicle stops is shortened, it is necessary to increase the speed at which hydraulic oil is discharged from the primary hydraulic chamber 516 to accelerate the shift control.

  As described above, when the discharge speed of the hydraulic oil from the primary hydraulic chamber 516 is increased, it is necessary to supply a large amount of hydraulic oil to the secondary hydraulic chamber 526 in a short time in order to prevent belt slip.

  However, in general, the engine speed NE decreases during braking, and the flow rate of oil output from the oil pump 310 also decreases.

  In such a situation, the oil pump 310 sucks air when the oil level of the oil pan 314 decreases due to high oil viscosity and slow oil return at low temperatures or when the oil level due to sudden braking is inclined. It is possible that air is sucked. When the oil pump 310 is in the air sucking state, the flow rate of the oil output from the oil pump 310 further decreases. Therefore, there is a concern that the amount of oil supplied to the secondary hydraulic chamber 526 is insufficient and belt slippage occurs.

  Therefore, in the present embodiment, when the target speed ratio calculation process (the process of S100 in FIG. 6) is performed, the flow rate of the oil output from the oil pump 310 during belt braking causes the belt slip during downshifting. When it is predicted that the amount of oil will be less than the amount of oil necessary for the suppression, the downshift control is allowed to proceed slowly until a predetermined time has elapsed since the start of the downshift, and the downshift control is rapidly advanced after the predetermined time has elapsed. In the present embodiment, downshift control will be described, but the control device according to the invention can also be applied to upshift control.

  FIG. 7 shows a functional block diagram of ECU 8000 which is the control device according to the present embodiment. ECU 8000 includes an input interface 8100, a calculation processing unit 8200, a storage unit 8300, and an output interface 8400.

  The input interface 8100 includes a vehicle speed V from the vehicle speed sensor 906, a hydraulic oil temperature T (C) from the oil temperature sensor 912, an accelerator opening A (CC) from the accelerator opening sensor 914, and a brake pedal from the pedal force sensor 916. The pedaling force SF, the acceleration α from the G sensor 926, and the oil flow rate FL from the flow sensor 928 are received and transmitted to the arithmetic processing unit 8200.

  Various information, programs, threshold values, maps, and the like are stored in the storage unit 8300, and data is read from or stored in the arithmetic processing unit 8200 as necessary.

  Arithmetic processing unit 8200 includes a braking determination unit 8210, an oil shortage prediction unit 8220, and a shift progress control unit 8230.

  The brake determination unit 8210 determines whether or not the vehicle is being braked. When determining that the vehicle is being braked, the brake determination unit 8210 determines that the flow rate of the oil output from the oil pump 310 is decreased due to the decrease in the engine speed NE, and the determination result is sent to the oil shortage prediction unit 8220. Send.

  When the oil shortage prediction unit 8220 receives the determination result from the braking determination unit 8210, whether or not the oil flow rate output from the oil pump 310 is less than the amount of oil necessary for suppressing belt slip during downshifting. Predict. For example, the oil shortage prediction unit 8220 determines that the flow rate of oil output from the oil pump 310 is a belt when it is estimated that the vehicle is suddenly braking and the oil pump 310 may be in an air sucking state. It is predicted that the amount of oil will be less than the amount of oil necessary to suppress slippage.

  If the oil shortage predicting unit 8220 predicts that the flow rate of the oil output from the oil pump 310 is insufficient, the shift advancement control unit 8230 slowly advances the shift control until a predetermined time elapses from the start of the shift. Shift control is rapidly advanced after the passage of time. For example, the shift progress control unit 8230 controls the progress of the shift control by controlling the target gear ratio. That is, in the process of S200 of FIG. 6 described above, the duty signal S2 (duty ratio D2) corresponding to the target gear ratio is output to DS (2) 2520 via the output interface 8400.

  The braking determination unit 8210, the oil shortage prediction unit 8220, and the shift progress control unit 8230 are all realized as software that is realized when the CPU that is the arithmetic processing unit 8200 executes the program stored in the storage unit 8300. Although described as functioning, it may be realized by hardware. Such a program is recorded on a storage medium and mounted on the vehicle.

  Referring to FIG. 8, the control structure of the program executed when ECU 8000 performs the target gear ratio calculation process (the process of S100 in FIG. 6) will be described.

  In S102, ECU 8000 determines whether or not the vehicle is being braked. For example, ECU 8000 determines that the vehicle is being braked when the pedal effort SF of the brake pedal exceeds a threshold value. If the vehicle is being braked (YES in S102), the process proceeds to S104. Otherwise (NO in S102), the process proceeds to S114.

  In S104, ECU 8000 determines whether or not sudden braking is being performed. Note that this process determines whether or not it is necessary to rapidly increase the target gear ratio in a short time until the vehicle stops in order to ensure the start performance (in other words, a large amount of hydraulic oil can be quickly added to the secondary hydraulic chamber. 526 to determine whether it is necessary to supply to 526. The ECU 8000 calculates the vehicle deceleration rate based on any one of the acceleration α from the G sensor 926, the vehicle speed V from the vehicle speed sensor 906, and the brake pedal depression force SF from the pedal force sensor 916. When the threshold value is exceeded, it is determined that sudden braking is in progress. If sudden braking is in progress (YES in S104), the process proceeds to S106. Otherwise (NO in S104), the process proceeds to S114.

  In S106, ECU 8000 determines whether hydraulic oil temperature T (C) is lower than a threshold value. This process is a process for estimating whether or not the oil pump 310 may be in an air sucking state based on the hydraulic oil temperature T (C). When the hydraulic oil temperature T (C) is lower than the threshold value, the ECU 8000 indicates that there is a possibility that the oil returns to the oil pan 314 is slow and the oil level of the oil pan 314 is lowered to enter the air sucking state. presume. If hydraulic oil temperature T (C) is lower than the threshold value (YES in S106), the process proceeds to S108. Otherwise (NO in S106), the process proceeds to S112.

  In S108, ECU 8000 sets the target gear ratio to a constant value γ (1). This γ (1) is set to a value of γ (0) <γ (1) <γmax, where γ (0) is the gear ratio at the start of braking (ie, at the start of downshifting).

  In S110, ECU 8000 determines whether or not a predetermined time T has elapsed since the start of shifting. The predetermined time T is set to a time shorter by a predetermined time than at least the vehicle stop time obtained from the vehicle speed and deceleration. The predetermined time T is set to a value longer than the time from the elapse of the predetermined time T to the end of the shift. When predetermined time T has elapsed (YES in S110), the process proceeds to S112. Otherwise (NO in S110), the process returns to S108.

  In S112, ECU 8000 sets the target gear ratio to the speed ratio γmax on the most deceleration side. Thereby, the start performance after a vehicle stop is ensured.

  In S114, ECU 8000 sets the target gear ratio to a normal value obtained from vehicle speed V and accelerator opening A (CC).

  A target speed ratio and belt clamping pressure controlled by ECU 8000 serving as the control apparatus according to the present embodiment based on the above-described structure and flowchart will be described with reference to FIG.

  Assume a case where the driver greatly depresses the brake pedal to stop the vehicle at time t1 when the vehicle is traveling with the target gear ratio being γ (0).

  If the depression force SF of the brake pedal exceeds the threshold value, it is determined that the vehicle is being braked (YES in S102). That is, it is determined that the engine speed NE is decreased due to braking of the vehicle, and the flow rate of oil output from the oil pump 310 is decreased.

  Further, when the vehicle deceleration exceeds a threshold value, it is determined that sudden braking is being performed (YES in S104). That is, it is determined that it is necessary to rapidly increase the target gear ratio to γmax in a short time until the vehicle stops in order to ensure the start performance after the vehicle stops.

  Here, as shown by the one-dot chain line in FIG. 9, when the target gear ratio is rapidly increased to the final value γmax at time t1, in order to prevent belt slip, It is necessary to supply the hydraulic oil to the secondary hydraulic chamber 526 in a short time. However, when the viscosity of the oil is high, the return of the oil to the oil pan 314 may be slow and the oil level of the oil pan 314 may be lowered to enter the air sucking state. When in the air sucking state, a large amount of oil cannot be supplied to the secondary hydraulic chamber 526 in a short time. Therefore, as shown by the alternate long and short dash line in FIG. 9, the belt clamping pressure decreases and belt slippage occurs.

  Therefore, ECU 8000 determines whether or not hydraulic oil temperature T (C) is lower than a threshold value (S106). Then, when hydraulic oil temperature T (C) is lower than the threshold value (YES in S106), ECU 8000 estimates that there is a possibility that the oil viscosity is high and an air sucking state may occur, as shown in FIG. As indicated by the solid line, the target gear ratio is maintained at γ (1) (γ (0) <γ (1) <γmax) at time t1 from time t1 to time t2 when the predetermined time T elapses (S108). , NO at S110).

  Thus, in the period from time t1 to time t2, the target speed ratio is maintained at γ (1), and therefore, belt slip is suppressed compared to when the target speed ratio is increased to γmax at time t1. Therefore, the amount of oil that needs to be supplied to the secondary hydraulic chamber 526 is reduced. Therefore, even during the period from time t1 to time t2, even when the air suction state occurs and the flow rate of oil output from the oil pump 310 decreases, the belt clamping pressure does not decrease and belt slippage is prevented. Is done.

  Further, ECU 8000 sets the target gear ratio from γ (1) to γmax, which is the final value, at the time when predetermined time T has elapsed from time t1 (time t2) (S112). In this way, the reduction in the transmission speed is suppressed, and the actual transmission ratio γ is set to γmax at time t3 immediately after the target transmission ratio is set to γmax. That is, the shift is completed early. As a result, the actual gear ratio γ can be set to γmax before the time t4 when the vehicle stops, so that the starting performance after the vehicle stops can be ensured.

  In the period from the start of the shift to the completion of the shift (the period from time t1 to time t3), the period during which the target speed ratio is maintained at γ (1) (the period from time t1 to time t2) is the target speed ratio. Is set longer than a period (a period from time t2 to time t3) in which γmax is set. As a result, a large amount of oil can be supplied to the secondary hydraulic chamber 526 during the period in which the target gear ratio is maintained at γ (1), so that a decrease in belt clamping pressure can be appropriately suppressed.

  As described above, according to the control device according to the present embodiment, when the downshift of the belt-type continuously variable transmission is performed, the oil flow rate output from the oil pump is the oil necessary for suppressing belt slip. If it is predicted that the amount will be less than the amount, the target gear ratio is maintained at a constant value γ (1) until a predetermined time has elapsed from the start of the shift, and the progress of the downshift control is delayed. Therefore, the oil shortage due to the sudden downshift is solved, and the belt slip can be suppressed. Further, after a predetermined time has elapsed, the target gear ratio is set to γmax, which is the final value, and the downshift control proceeds rapidly. Thereby, the fall of the speed change as a whole is suppressed. For this reason, it is possible to achieve both suppression of belt slip at the time of downshift and suppression of decrease in transmission speed without complicating the structure of the continuously variable transmission.

  In the present embodiment, the case where the progress of the downshift control is delayed by maintaining the target speed ratio from the start of the downshift until the predetermined time T elapses in the flowchart of FIG. 8 has been described. The method of delaying the progress of the shift control is not limited to this.

  For example, the progress of the downshift control is delayed by controlling the increase speed of the target speed ratio from the start of the shift until the predetermined time T elapses to be larger than the increase speed of the target speed ratio after the predetermined time has elapsed. You may do it.

  Further, instead of the target gear ratio, the oil amount in the primary hydraulic chamber 516 is controlled by directly controlling the duty ratio D2 of DS (2) 2520 (that is, the discharge speed of hydraulic oil from the primary hydraulic chamber 516). It may be.

  That is, until a predetermined time T has elapsed from the start of the downshift, the oil amount in the primary hydraulic chamber 516 is reduced to a constant value between the oil amount at the start of the downshift and the oil amount at the completion of the downshift, The duty ratio D2 may be controlled so that the oil amount in the primary hydraulic chamber 516 is reduced to the oil amount at the completion of the downshift after the predetermined time T has elapsed.

  Further, until the predetermined time T has elapsed from the start of the downshift, the duty ratio D2 is set to a value (for example, 50%) lower than the maximum value (100%), and the oil amount in the primary hydraulic chamber 516 is gradually discharged. Alternatively, the duty ratio D2 may be set to the maximum value (100%) after the elapse of the predetermined time T, and the oil amount in the primary hydraulic chamber 516 may be discharged rapidly.

  Further, in the present embodiment, a case has been described in which it is estimated based on the hydraulic oil temperature T (C) whether or not there is a possibility of being in an air sucking state in the processing of S104 in FIG. A method for estimating whether or not there is a possibility of a sucking state is not limited to this.

  For example, when the flow rate FL of oil from the flow rate sensor 928 is smaller than a threshold value, it may be estimated that there is a possibility that an air sucking state may occur or an air sucking state. Further, the vehicle deceleration rate is calculated based on the acceleration α from the G sensor 926, the vehicle speed V from the vehicle speed sensor 906, or the depression force SF of the brake pedal from the pedal force sensor 916, and the calculated deceleration rate has a threshold value. When it exceeds, you may make it estimate that the inclination of the oil level of the oil pan 314 is large and may be in an air sucking state.

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

1 is a skeleton diagram of a vehicle equipped with an ECU that is a control device according to an embodiment of the present invention. It is a control block diagram of ECU. FIG. 2 is a first diagram illustrating a hydraulic control circuit. FIG. 3 is a second diagram illustrating a hydraulic control circuit. FIG. 6 is a third diagram illustrating the hydraulic control circuit. It is a flowchart (the 1) which shows the control structure of ECU. It is a functional block diagram of ECU. It is a flowchart (the 2) which shows the control structure of ECU. 3 is a timing chart of a target gear ratio and belt clamping pressure controlled by an ECU.

Explanation of symbols

  100 drive device, 200 engine, 300 torque converter, 310 oil pump, 312 strainer, 314 oil pan, 400 forward / reverse switching device, 402 sun gear, 404 carrier, 406 forward clutch, 408 ring gear, 410 reverse brake, 500 continuously variable transmission , 502 Input shaft, 506 Output shaft, 510 Primary pulley, 512, 522 Fixed sheave, 514, 524 Movable sheave, 516 Primary hydraulic chamber, 520 Secondary pulley, 526 Secondary hydraulic chamber, 530 Transmission belt, 600 Reduction gear, 700 Differential Gear device, 800 drive wheel, 902 engine speed sensor, 904 turbine speed sensor, 906 vehicle speed sensor, 908 throttle opening sensor, 910 cooling water temperature sensor, 912 Oil temperature sensor, 914 accelerator opening sensor, 916 foot brake switch, 918 position sensor, 920 shift lever, 922 primary pulley rotation speed sensor, 924 secondary pulley rotation speed sensor, 926 G sensor, 928 flow sensor, 1000 electronic throttle valve, DESCRIPTION OF SYMBOLS 1100 Fuel injection device, 1200 Ignition device, 2000 Hydraulic control circuit, 2002 Line pressure oil path, 2100 Primary regulator valve, 2102 Secondary regulator valve, 2200 SLT linear solenoid valve, 2210 SLS linear solenoid valve, 2310 Modulator valve (1), 2330 Modulator valve (3), 2340 Modulator valve (4), 2312 Pressure sensor, 2400 Control valve , 2510 shift control duty solenoid (1), 2520 shift control duty solenoid (2), 2600 manual valve, 2710 ratio control valve (1), 2720 ratio control valve (2), 8000 ECU, 8100 input interface, 8200 arithmetic Processing unit, 8210 braking determination unit, 8220 oil shortage prediction unit, 8230 shift progress control unit, 8300 storage unit, 8400 output interface.

Claims (20)

A control device for a belt-type continuously variable transmission that is provided between a drive source and a drive wheel and continuously changes a gear ratio using oil output from an oil pump,
Predicting means for predicting whether or not the flow rate of the oil output from the oil pump is less than the amount of oil required during the shift control of the continuously variable transmission;
When it is predicted by the prediction means that the oil flow rate is insufficient, the shift control is progressed in the first period from the start of the shift until a predetermined time elapses than when the oil flow rate is not predicted to be insufficient. Control means for controlling the continuously variable transmission so as to delay and advance the shift control more rapidly than the first period in the second period from the elapse of the first period to the completion of the shift. A control device for a continuously variable transmission.   When the speed ratio of the continuously variable transmission is changed from the value at the start of the shift to the value at the end of the shift, the control means sets the speed ratio to the value at the start of the shift and the shift completion in the first period. 2. The continuously variable transmission control device according to claim 1, wherein the transmission ratio is changed from the constant value to a value at the time of completion of the shift in the second period. .   The control means changes the speed ratio at the first change speed in the first period when changing the speed ratio of the continuously variable transmission, and changes the speed ratio from the elapse of the first period to the completion of the speed change. 2. The continuously variable transmission control device according to claim 1, wherein the speed ratio is changed at a second change speed larger than the first change speed in a period of 2. The continuously variable transmission includes a pair of pulleys around which a belt is wound, a first hydraulic cylinder that changes the gear ratio of the continuously variable transmission by changing the groove width of one pulley, and the other pulley. A second hydraulic cylinder that changes the belt clamping pressure by changing the groove width of the belt, and a first pressure regulating valve that adjusts the amount of oil in the first hydraulic cylinder using oil output from the oil pump And a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder using oil output from the oil pump,
The prediction means predicts whether or not the flow rate of the oil is less than the amount of oil necessary for suppressing belt slip at the time of downshift of the continuously variable transmission,
When the control means predicts that the oil flow rate is insufficient by the prediction means when the continuously variable transmission is downshifted with the groove width of the first pulley widened, the first period The amount of oil in the first hydraulic cylinder is decreased to a constant value between a value at the start of the downshift and a value at the completion of the downshift, and the first hydraulic cylinder is reduced in the second period. 2. The continuously variable transmission control device according to claim 1, wherein the first pressure regulating valve is controlled so as to reduce the amount of oil from the constant value to a value at the time of completion of the shift. The continuously variable transmission is wound around a first pulley connected to the drive source, a second pulley connected to the drive wheel, the first pulley, and the second pulley. A belt, a first hydraulic cylinder that changes the gear ratio of the continuously variable transmission by changing the groove width of the first pulley, and a groove width of the belt by changing the groove width of the second pulley. A second hydraulic cylinder that changes pressure, a first pressure regulating valve that adjusts the amount of oil in the first hydraulic cylinder using oil output from the oil pump, and oil that is output from the oil pump. And a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder by using,
The predicting means predicts whether or not the oil output amount is less than an oil amount necessary for suppressing belt slip at the time of downshift of the continuously variable transmission,
When the control means predicts that the oil output amount is insufficient when the downshift of the continuously variable transmission is performed by widening the groove width of the first pulley, the first period The first hydraulic cylinder is discharged at a first discharge speed at a first discharge speed, and the second discharge speed is greater than the first discharge speed during the second period. The control device for a continuously variable transmission according to claim 1, wherein the first pressure regulating valve is controlled so as to be discharged.   The control device for a continuously variable transmission according to any one of claims 1 to 5, wherein the first period is longer than the second period. The control device further includes a deceleration rate calculation means for calculating a deceleration rate of the vehicle,
The continuously variable transmission according to any one of claims 1 to 6, wherein the predicting unit predicts that the flow rate of the oil is insufficient when the deceleration rate calculated by the deceleration rate calculating unit is larger than a threshold value. Control device. The control device further includes oil temperature detection means for detecting the temperature of the oil,
The continuously variable transmission according to any one of claims 1 to 6, wherein the predicting means predicts that the flow rate of the oil is insufficient when the temperature detected by the oil temperature detecting means exceeds a threshold value. Control device.   The prediction means estimates whether or not the oil pump is in an air sucking state in which air is sucked, and predicts that the flow rate of the oil is insufficient when it is estimated that the oil pump is in the air sucking state. Item 7. The control device for the continuously variable transmission according to any one of Items 1 to 6. The control device further includes a flow rate detection means for detecting the flow rate of the oil,
The control device for a continuously variable transmission according to claim 9, wherein the predicting means estimates that the air sucking state is present when the flow rate of the oil detected by the flow rate detecting means is smaller than a threshold value. A control method performed by a control device that controls a belt-type continuously variable transmission that is provided between a drive source and a drive wheel and continuously changes a gear ratio using oil output from an oil pump,
A predicting step of predicting whether or not the flow rate of the oil output from the oil pump is less than the amount of oil required during the shift control of the continuously variable transmission;
When it is predicted that the oil flow rate is insufficient in the prediction step, the shift control is progressed in a first period from the start of the shift until a predetermined time elapses, compared to a case where the oil flow rate is not predicted to be insufficient. A control step of controlling the continuously variable transmission so that the shift control progresses more rapidly than the first period in the second period from the elapse of the first period until the completion of the shift. A method for controlling a continuously variable transmission.   In the control step, when changing the transmission ratio of the continuously variable transmission from a value at the start of shifting to a value at the completion of shifting, the speed ratio is changed from the value at the start of shifting to the value at the start of shifting. 12. The continuously variable transmission control method according to claim 11, wherein a constant value is maintained between the time value and the speed ratio is changed from the constant value to a value at the time of completion of the shift in the second period. .   In the control step, when changing the transmission ratio of the continuously variable transmission, the transmission ratio is changed at a first change speed in the first period, and after the first period elapses until the transmission is completed. The continuously variable transmission control method according to claim 11, wherein the speed ratio is changed at a second change speed larger than the first change speed in a period of 2. The continuously variable transmission includes a pair of pulleys around which a belt is wound, a first hydraulic cylinder that changes the gear ratio of the continuously variable transmission by changing the groove width of one pulley, and the other pulley. A second hydraulic cylinder that changes the belt clamping pressure by changing the groove width of the belt, and a first pressure regulating valve that adjusts the amount of oil in the first hydraulic cylinder using oil output from the oil pump And a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder using oil output from the oil pump,
The predicting step predicts whether or not the flow rate of the oil is less than an oil amount necessary for suppressing belt slip at the time of downshift of the continuously variable transmission,
In the control step, when the groove width of the first pulley is widened and the continuously variable transmission is downshifted, if the oil flow rate is predicted to be insufficient in the prediction step, the first period The amount of oil in the first hydraulic cylinder is decreased to a constant value between a value at the start of the downshift and a value at the completion of the downshift, and the first hydraulic cylinder is reduced in the second period. The control method of the continuously variable transmission according to claim 11, wherein the first pressure regulating valve is controlled so as to reduce the amount of oil from the constant value to a value at the time of completion of the shift. The continuously variable transmission is wound around a first pulley connected to the drive source, a second pulley connected to the drive wheel, the first pulley, and the second pulley. A belt, a first hydraulic cylinder that changes the gear ratio of the continuously variable transmission by changing the groove width of the first pulley, and a groove width of the belt by changing the groove width of the second pulley. A second hydraulic cylinder that changes pressure, a first pressure regulating valve that adjusts the amount of oil in the first hydraulic cylinder using oil output from the oil pump, and oil that is output from the oil pump. And a second pressure regulating valve that adjusts the amount of oil in the second hydraulic cylinder by using,
The predicting step predicts whether or not the oil output amount is less than an oil amount necessary for suppressing belt slip at the time of downshift of the continuously variable transmission,
In the control step, when it is predicted that the oil output amount is insufficient in the prediction step when the continuously variable transmission is downshifted by widening the groove width of the first pulley, the first period The first hydraulic cylinder is discharged at a first discharge speed at a first discharge speed, and the second discharge speed is greater than the first discharge speed during the second period. The control method of the continuously variable transmission according to claim 11, wherein the first pressure regulating valve is controlled so as to be discharged at a low pressure.   The control method for a continuously variable transmission according to any one of claims 11 to 15, wherein the first period is longer than the second period. The control method further includes a deceleration rate calculation step of calculating a deceleration rate of the vehicle,
The continuously variable transmission according to any one of claims 11 to 16, wherein the predicting step predicts that the flow rate of the oil is insufficient when the deceleration rate calculated in the deceleration rate calculation step is larger than a threshold value. Control method. The control method further includes an oil temperature detection step of detecting the temperature of the oil,
The continuously variable transmission according to any one of claims 11 to 16, wherein the predicting step predicts that the flow rate of the oil is insufficient when the temperature detected in the oil temperature detecting step exceeds a threshold value. Control method.   The predicting step estimates whether or not the oil pump is in an air sucking state in which air is sucked, and predicts that the flow rate of the oil is insufficient when the air pump is estimated to be in the air sucking state. Item 17. A control method for a continuously variable transmission according to any one of items 11 to 16. The control method further includes a flow rate detecting step of detecting the flow rate of the oil,
20. The continuously variable transmission control method according to claim 19, wherein the predicting step estimates that the air is sucked when the flow rate of the oil detected in the flow rate detecting step is smaller than a threshold value.

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