JP4436286B2 - Belt type continuously variable transmission - Google Patents

Description

  The present invention relates to a belt-type continuously variable transmission that enables a stepless speed change by changing the groove width of each pulley based on the thrust of a driving pulley and a driven pulley that span the belt.

In the belt type continuously variable transmission, since power is transmitted by a belt stretched between a driving pulley and a driven pulley, it is important to prevent the belt from slipping. Therefore, in the conventional belt type continuously variable transmission, the target driven pulley pressure is obtained from the target gear ratio and the input torque, the target driven pulley pressure is calculated from the target driven pulley pressure and the speed change speed, and the target drive pulley is calculated. When the pressure is equal to or lower than the belt slip lower limit pressure, the target driven pulley pressure is calculated backward from the drive pulley side belt slip lower limit pressure. In this way, the target drive pulley pressure and the target driven pulley pressure are calculated to prevent the belt from slipping (see, for example, Patent Document 1).
JP 2000-18347 A

  However, in the prior art, when shifting is performed by reducing the drive pulley pressure during downshifting, the drive pulley pressure may reach the belt slip lower limit pressure, which may cause belt slip.

  The present invention has been made in view of these facts, and provides a belt-type continuously variable transmission that can improve the fuel efficiency by reducing the pulley pressure while ensuring the pulley pressure that does not cause the belt to slip. The purpose is to provide.

  The present invention provides a drive pulley thrust generating means for generating a target drive pulley thrust for realizing a target speed ratio by spanning a belt between the drive pulley and the driven pulley and sandwiching the belt with the drive pulley. In a belt-type continuously variable transmission comprising driven pulley thrust generating means for generating a target driven pulley thrust for realizing a target gear ratio by sandwiching the belt with the driven pulley, the drive pulley causes the belt to slide Driving torque capacity securing pulley thrust means for calculating the driving torque capacity securing pulley thrust to be pinched and driving speed ratio retaining pulley thrust calculation for calculating the driving speed ratio retaining pulley thrust required to maintain the current actual speed ratio And a driven torque capacity securing pulley for calculating a driven gear ratio holding pulley thrust that the driven pulley holds without sliding the belt. Thrust calculation means, driven gear ratio holding pulley thrust calculation means for calculating driven gear ratio holding pulley thrust required to maintain the current actual gear ratio, and driving required to achieve the target gear speed Gear speed pulley thrust difference calculation means for calculating a pulley speed difference for a target speed between the pulley thrust and the driven pulley thrust, and a speed ratio feedback in the drive pulley or the driven pulley based on the difference between the target speed ratio and the actual speed ratio A gear ratio feedback pulley thrust difference calculating means for calculating a pulley thrust difference for the gear, and adding the target gear speed pulley thrust difference and the gear ratio feedback pulley thrust difference to obtain a gear shift thrust; If the shift thrust in the shift direction in which the shift is small is positive, and the shift thrust becomes a positive value, the drive torque capacity securing pulley thrust and the variable thrust The target drive pulley thrust is set according to the absolute value of thrust and the absolute value of the drive gear ratio holding pulley thrust, and the driven torque capacity securing pulley thrust is set as the target driven pulley thrust, and the shift thrust is a negative value. The driving torque capacity securing pulley thrust is set as the target driving pulley thrust, and the driven torque capacity securing pulley thrust, the absolute value of the speed change thrust, and the absolute value of the driven speed ratio holding pulley thrust are And a target pulley thrust calculating means for setting the target driven pulley thrust.

  The present invention calculates the driving / driven torque capacity securing pulley thrust for clamping the belt without slipping, and controls the hydraulic pressure acting on each pulley to be equal to or greater than the driving / driven torque capacity securing pulley thrust even during gear shifting. As a result, it is possible to reliably avoid poor shifting and to improve fuel efficiency by using the hydraulic pressure acting on the driven pulley during shifting as the driven torque capacity securing pulley thrust.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 schematically shows a V-belt continuously variable transmission according to the present invention. This V-belt continuously variable transmission 1 has a primary pulley 2 and a secondary pulley 3 arranged so that their V-grooves are aligned, The V belt 4 is wound around the V grooves of the pulleys 2 and 3. The primary pulley (drive pulley) 2 has an engine 5 disposed coaxially, and a lockup torque converter 6 and a forward / reverse switching mechanism 7 are sequentially disposed between the engine 5 and the primary pulley 2 from the engine 5 side.

  The rotation to the primary pulley 2 is transmitted to the secondary pulley (driven pulley) 3 via the V-belt 4, and the rotation of the secondary pulley 3 is then applied to a wheel (not shown) via the output shaft 8, the gear set 9 and the differential gear device 10. It reaches.

  Among the flanges forming the V-grooves of the primary pulley 2 and the secondary pulley 3 in order to change the rotational transmission ratio (hereinafter referred to as “speed ratio”) between the primary pulley 2 and the secondary pulley 3 during the power transmission. One is a fixed flange 2a, 3a, and the other flange 2b, 3b is a movable flange displaceable in the axial direction. These movable flanges 2b and 3b are respectively supplied with a primary pulley pressure Ppri and a secondary pulley pressure Psec, which are produced using a line pressure controlled as described later as a source pressure, to the primary pulley chamber 2c and the secondary pulley chamber 3c, respectively. The thrust toward the fixed flanges 2a and 3a is generated, and the V-belt 4 is sandwiched between the pulley flanges to enable the power transmission between the primary pulley 2 and the secondary pulley 3.

  However, when shifting, the V grooves of both pulleys 2 and 3 are changed by the differential pressure between the primary pulley pressure Ppri and the secondary pulley pressure Psec generated corresponding to the target gear ratio, as will be described later. The target gear ratio is realized by continuously changing the winding arc diameter of the V belt 4 with respect to the pulleys 2 and 3.

  Outputs of the primary pulley pressure Ppri and the secondary pulley pressure Psec are controlled by a shift control hydraulic circuit 11, and the shift control hydraulic circuit 11 is controlled in response to a signal from the transmission controller 12. Therefore, the transmission controller 12 has a signal from the primary pulley rotation sensor 13 that detects the primary pulley rotation speed Npri, a signal from the secondary pulley rotation sensor 14 that detects the secondary pulley rotation speed Nsec, and the depression of the accelerator pedal. A selection mode from a manual shift switch 17 that detects a signal from an accelerator pedal stroke sensor 16 that detects a stroke and a manual shift mode that prioritizes a shift by a driving operation or an automatic shift mode according to a shift command from the transmission controller 12 A fuel consumption request signal from an economy mode switch 19 for requesting driving with a focus on fuel consumption, a signal, a selection range signal from the inhibitor switch 17, a brake switch 18 for detecting depression of the brake pedal When, and a signal that relates to the transmission input torque Ti from an engine controller 20 for controlling the engine 5 (such as engine speed and fuel injection time).

  FIG. 2 is a system diagram showing the transmission control hydraulic circuit 11 and the transmission controller 12. First, the transmission control hydraulic circuit 11 will be described. The circuit 11 includes an oil pump 21 that is driven by an engine. The hydraulic oil from the pump 21 to the oil passage 22 is used as a medium, and the pressure is adjusted to a predetermined line pressure PL by a pressure regulator valve 23.

  One of the line pressures PL of the oil passage 22 is adjusted by the pressure reducing valve 24 as the primary pulley pressure Ppri and supplied to the primary pulley chamber 2C, and the other is adjusted by the pressure reducing valve 25 as the secondary pulley pressure Psec, and the secondary pulley chamber 3C. To be supplied. However, the pressure regulator valve 23 controls the line pressure PL by the driving duty to the solenoid 23a, and the pressure reducing valves 24 and 25 control the primary pulley pressure Ppri and the secondary pulley pressure Psec by the driving duty to the solenoids 24a and 25a, respectively. To do.

  Further, the solenoid drive duty of the pressure regulator valve 23 and the solenoid drive duty of the pressure reducing valves 24 and 25 are determined by the transmission controller 12. That is, the transmission control hydraulic circuit 11 and the transmission controller 12 correspond to the drive pulley thrust generation means and the driven pulley thrust generation means.

  As will be described later, the transmission controller 12 determines the target gear ratio I from a map (not shown) from the accelerator pedal depression stroke and the vehicle speed VSP (here, the secondary pulley Nsec is multiplied by a predetermined constant). Ask. Then, an actual transmission ratio i is obtained from the primary pulley rotation speed Npri and the secondary pulley rotation speed Nsec, and a target transmission speed V (() using a map set in advance from the deviation between the target transmission ratio I and the actual transmission ratio i is used. I) is calculated. Further, the transmission controller 12 calculates a feedback control amount using a known PI feedback control or the like so as to eliminate the deviation between the target speed ratio I and the actual speed ratio i.

  FIG. 3 is a flowchart showing an example of hydraulic control executed by the transmission controller 12. This flowchart is repeatedly executed every predetermined time, for example, several tens of msec after the engine start is detected by turning on the ignition key or the like. The

  First, in step S1, the primary torque capacity securing pulley thrust Fpri (f1) that the primary pulley 2 grips without sliding the V belt 4 and the secondary torque capacity securing pulley thrust Fsec that the secondary pulley 3 grips without sliding the V belt 4 (F1) is calculated from the transmission input torque Ti, the actual transmission ratio i, and the friction coefficient of the oil used.

  In the subsequent step S2, gear ratio holding pulley thrusts Fpri (f2) and Fsec (f2) of each pulley necessary for maintaining the current actual gear ratio are calculated. The transmission ratio maintaining pulley thrusts Fpri (f2) and Fsec (f2) are balanced hydraulic pressures that are actual transmission ratios based on the torque capacity securing pulley thrust F (f1) calculated in step S1, the current actual transmission ratio i, and the pulley ratio. Is calculated by subtracting the torque capacity securing pulley thrust F (f1) from the balance hydraulic pressure.

  Next, in step S3, a shift speed pulley thrust difference F (v) required to achieve the target shift speed V (I) determined based on the driving state is calculated. That is, step S3 corresponds to a shift speed pulley thrust difference calculation means. Note that the shift speed pulley thrust difference F (v) may be calculated using, for example, a subroutine shown in FIG.

  In step S4, a gear ratio feedback pulley thrust difference F (fb) in the primary pulley 2 or the secondary pulley 3 is calculated based on the difference between the target gear ratio I and the actual gear ratio i. That is, step S4 corresponds to gear ratio feedback pulley thrust difference calculation means. The gear ratio feedback pulley thrust difference F (fb) is calculated using, for example, a subroutine shown in FIG.

  In step S5, the transmission speed pulley thrust difference F (v) calculated in step S3 and the transmission ratio feedback pulley thrust difference F (fb) calculated in step S4 are added to obtain a transmission thrust F (th). Is calculated.

  Here, the shift thrust in the direction in which the gear ratio decreases the pulley ratio (upshift) is set to positive (+), and the shift thrust in the direction to increase the pulley ratio (downshift) is set to negative (-).

  In subsequent step S6, the shift thrust F (th) and the predetermined value F are compared. Specifically, the predetermined value F = 0 is set, and it is determined whether or not the shift thrust F (th) exceeds the predetermined value F = 0.

  Therefore, if it is determined in step S6 that the shift thrust F (th)> 0 and the upshift is being performed, in step S7, the primary torque capacity securing pulley thrust Fpri (f1) calculated in step S1 is set. The target drive pulley thrust Fpri (o) is calculated by adding the transmission thrust F (th) calculated in step S5 and the primary transmission ratio maintaining pulley thrust Fpri (f2) calculated in step S2. In step S8, the secondary torque capacity securing pulley thrust Fsec (f1) calculated in step S1 is directly used as the target driven pulley thrust Fsec (o) (= Fsec (f1)).

  If it is determined in step S6 that the shift thrust F (th) ≦ 0 and the downshift is being performed, in step S9, the primary torque capacity securing pulley thrust Fpri (f1) calculated in step S1 is used as the target drive. The pulley thrust is Fpri (= Fpri (f1)). In step S10, the secondary torque capacity securing pulley thrust Fsec (f1) calculated in step S1, the absolute value | F (th) | of the transmission thrust calculated in step S5, and the secondary transmission ratio holding pulley thrust calculated in step S2. The absolute value | Fsec (f2) | is added to calculate the target driven pulley thrust Fsec (o).

  In step S11, the target drive pulley pressure Ppri (o) to be regulated by the pressure reducing valve 24 is calculated based on the target drive pulley thrust Fpri (o) calculated in step S6 or 8. Specifically, the target drive pulley pressure Ppri (o) is calculated by dividing the target drive pulley thrust Fpri (o) by the pressure receiving area Spri of the primary pulley chamber 2C. In step S12, the target driven pulley pressure Psec (o) to be regulated by the pressure reducing valve 25 is calculated based on the target driven pulley thrust Fsec (o) calculated in step S8 or 9. Specifically, the target drive pulley pressure Psec is calculated by dividing the target drive pulley thrust Fsec by the pressure receiving area Ssec of the secondary pulley chamber 3C.

  It should be noted that the relationship between the shift direction and the shift thrust set in step S5 may be set in reverse. That is, the shift thrust in the direction in which the gear shift direction decreases the pulley ratio (upshift) is set to negative (−), and the shift thrust in the direction to increase the pulley ratio (downshift) is set to positive (+). In this case, the determination in step S6 is control in which the shift thrust F (th) is less than 0 and the process proceeds to step S7, and when it is 0 or more, the process proceeds to step S9.

  Hereinafter, the calculation method used in step S3 and step S4 will be exemplified.

  FIG. 4 is a subroutine illustrating a method for calculating the shift speed pulley thrust difference F (v) executed in step S3.

  Referring to FIG. 4, first, in step S21, the target shift speed V (I) is determined based on the driving state such as the vehicle speed VSP, the selection range signal, the selection mode signal, and the accelerator pedal stroke amount obtained from the secondary pulley rotation speed Nsec. calculate. Next, in step S22, using the conversion magnification calculation map shown in FIG. 6, the conversion magnification mg (= Vp / V (I)) corresponding to the actual pulley ratio ip is obtained based on this map, and this conversion magnification mg. Is multiplied by the target shift speed V (I) in step S23 to calculate the pulley axial change speed Vp (= mg × V (I)).

  Then, in step S24, the transmission speed pulley thrust difference F (v) is obtained based on the pulley change speed Vp calculated in step S23 using the transmission speed pulley thrust difference calculation map shown in FIG. In the map of this embodiment, when the target pulley ratio Ip is large (in the negative (−) direction at the time of downshift), the shift pulley pulley thrust difference F (v) is equal to the secondary pulley thrust Fsec. When the target pulley ratio Ip is set to be large (the direction is positive (+) at the time of upshift), the shift speed pulley thrust difference F (v) is the primary pulley thrust Fpri. Is set to be large. In the map of FIG. 7, the side on which the target pulley ratio Ip becomes larger, that is, the secondary pulley thrust Fsec, among the gear shift speed thrust thrust difference F (v), achieves the target gear shift speed V (I) calculated in step S21. It is set to a value obtained by adding a predetermined margin or margin ratio to the shift speed pulley thrust difference necessary for this.

  FIG. 5 is a subroutine illustrating the method for calculating the transmission ratio feedback pulley thrust difference F (fb) executed in step S4.

  Referring to FIG. 5, first, in step S31, the actual speed ratio i is subtracted from the target speed ratio I to calculate a deviation between the target speed ratio I and the actual speed ratio i, and this deviation is used in step S32. The previous value of the integral deviation of the transmission system is added and updated to a new integral deviation. In step S33, a proportional compensation amount is calculated by multiplying the deviation calculated in step S31 by the proportional gain of the transmission system. Similarly, in step S34, an integral compensation amount is calculated by multiplying the integral deviation calculated in step S32 by the integral gain of the transmission system. In step S35, the gear ratio feedback pulley thrust difference F (fb) is added to the primary pulley 2 or the secondary pulley 3 by adding the proportional compensation amount calculated in step S33 and the integral compensation amount calculated in step S34. Is calculated. In this embodiment, the PI control has been described. However, any control method itself such as PID control may be used as long as it controls feedback control.

  Next, a specific operation of this embodiment will be described with reference to a time chart shown in FIG.

  First, until the time T1 when the accelerator is closed, the hydraulic pressure obtained by adding the torque capacity ensuring hydraulic pressure and the transmission ratio maintaining hydraulic pressure is applied to the primary pulley 3, and only the torque capacity ensuring hydraulic pressure is applied to the secondary pulley 4.

  When the driver depresses the accelerator pedal greatly at time T1 to request a so-called step-down downshift, the primary pulley pressure Ppri remains a steady hydraulic pressure based on the primary torque capacity securing pulley thrust Fpri (f1), but the secondary pulley The pressure Psec is controlled to a hydraulic pressure based on the target driven pulley thrust Fsec (o) obtained by adding the secondary torque capacity securing pulley thrust Fsec (f1) and the absolute value | F (th) | of the shift thrust. That is, the shift control by the secondary pulley pressure Psec is executed during the time T1 to T2 when the step-down downshift is executed.

  More specifically, the area indicated by the dots represents the hydraulic pressure corresponding to the transmission ratio maintaining pulley thrust F (f2), the area indicated by the oblique lines represents the hydraulic pressure corresponding to the pulley thrust difference for transmission speed F (v), and the bold solid line The final command oil pressure is obtained by adding the gear ratio feedback pulley thrust difference F (fb) to the two oil pressures.

  For example, when the actual gear ratio follows the target gear ratio with a delay with respect to the target gear ratio, as shown in FIG. 8, at the time of a sudden gear change, the command hydraulic pressure rises rapidly first, and then the actual gear ratio exceeds the target gear ratio. The command hydraulic pressure is reduced until the hydraulic pressure corresponding to the gear ratio holding pulley thrust F (f2) or the hydraulic pressure corresponding to the gear speed pulley thrust difference F (v) is interrupted and becomes the supporting hydraulic pressure that matches the secondary torque capacity securing hydraulic pressure. To do. In this way, torque capacity can be ensured and the hydraulic pressure required for shifting can be minimized.

  An upshift is performed from time T4 to T5. At this time, the gear shift is performed by controlling the primary pulley pressure Ppri. For example, when the difference between the target gear ratio and the actual gear ratio changes as shown in FIG. The hydraulic pressure corresponds to the hydraulic pressure corresponding to the transmission ratio maintaining pulley thrust F (f2), the hydraulic pressure corresponding to the transmission speed pulley thrust difference F (v), and the torque capacity securing hydraulic pressure.

  The flowchart shown in FIG. 9 is a subroutine illustrating another method for calculating the gear ratio feedback pulley thrust difference F (fb) executed in step S4. This calculation method is characterized in that a torque is used for correction when calculating the gear ratio feedback pulley thrust difference.

  First, in step S51, the actual speed ratio i and the target speed ratio I are input, and the deviation is calculated. In step S52, a feedback control amount is calculated based on the calculated deviation. In step S53, the gear ratio feedback pulley thrust difference F (fb) is calculated based on the feedback control amount in the same manner as in step S4.

  In step S54, the primary torque capacity securing pulley thrust Fpri (f1) and the hydraulic pressure corresponding to this thrust are calculated in the same manner as in step S1, and the correction coefficient k1 is set based on the hydraulic pressure calculated in step S55. Here, the correction coefficient k1 is set so that the correction coefficient increases as the calculated hydraulic pressure increases.

  In step S56, the gear ratio feedback pulley thrust difference F (fb) is multiplied by the correction coefficient k1 set in step S55 to obtain the final gear ratio feedback pulley thrust difference F (fb).

  Thus, by correcting the gear ratio feedback pulley thrust difference F (fb) using torque, the stability of the control system is increased. For example, even when the input torque, the rotational speed, or the gear ratio changes greatly, The correction by the gear ratio feedback can be optimally reflected.

  FIG. 10 is a time chart for explaining the operation when the above-described method for calculating the gear ratio feedback pulley thrust difference is used. It is assumed that the actual speed ratio between times T2 and T3 is larger than the actual speed ratio between times T6 and T7.

  Assume that the difference α between the target speed ratio and the actual speed ratio from time T2 to T3 is equal to the difference α between the target speed ratio and the actual speed ratio from time T6 to T7. Therefore, the feedback control amount β calculated by multiplying the difference α by the gain is also equal. In order to correct this difference, the primary hydraulic pressure corresponding to the primary gear ratio feedback pulley thrust difference Fpri (fb) based on the feedback control amount β rises, but the speed difference between times T2 and T3 increases. And the primary hydraulic pressure increase corresponding to the primary gear ratio feedback pulley thrust difference Fpri (fb) that corrects the speed difference between times T6 and T7 becomes equal.

  However, since the torque capacity securing pulley thrust F (f1) is different between the times T2 and T3 and between the times T6 and T7, the responsiveness within each time is different.

  Therefore, in the above calculation method, the correction coefficient k1 is set based on the torque capacity securing pulley thrust F (f1), and the primary gear ratio feedback pulley thrust difference Fpri (fb) is corrected by this correction coefficient k1 to obtain the final value. In order to determine a pulley speed difference feedback pulley Fpri (fb) for primary speed ratio feedback, a speed ratio feedback thrust difference between times T2 and T3 and a speed ratio feedback thrust difference between times T6 and T7 Can be optimized.

  The flowchart shown in FIG. 11 is a subroutine illustrating another method for calculating the gear ratio feedback pulley thrust difference F (fb) executed in step S4. This calculation method is characterized in that, when calculating the gear ratio feedback pulley thrust difference, correction is performed using the actual transmission speed.

  First, in step S51, the actual speed ratio i and the target speed ratio I are input, and the deviation is calculated. In step S52, a feedback control amount is calculated based on the calculated deviation. In step S53, a gear ratio feedback pulley thrust difference F (fb) is calculated based on the feedback control amount.

  In step S64, an actual shift speed is calculated, and a correction coefficient k2 is set based on the actual shift speed calculated in step S65. Here, the correction coefficient k2 is set so that the correction coefficient increases as the calculated actual shift speed increases, and the correction coefficient decreases as the actual shift speed decreases.

  The reason for changing the control gain (correction coefficient) of the speed ratio feedback according to the speed change is as follows. Usually, as shown in FIG. 7, the thrust difference between the pulleys changes according to the shift speed. Assume that the actual gear ratio follows the target gear ratio with a feedback control amount calculated with a certain gear speed deviation when the gear speed is slow. When this feedback control amount is used even when the shift speed is high, the thrust difference is large, so the ratio of the thrust corresponding to the feedback control amount to the total thrust is reduced, and the feedback effect is reduced. Therefore, in order to change the feedback control amount according to the shift speed, a control gain (correction coefficient) according to the change speed is used.

  In step S66, the gear ratio feedback pulley thrust difference F (fb) is multiplied by the correction coefficient k2 set in step S65 to obtain the final gear ratio feedback pulley thrust difference F (fb).

  By correcting the gear ratio feedback pulley thrust difference F (fb) using the actual transmission speed in this way, the stability of the control system is improved. For example, even when the actual transmission speed changes greatly, the transmission ratio feedback The correction by can be reflected optimally.

  FIG. 12 is a time chart for explaining the operation when the above-described method for calculating the gear ratio feedback pulley thrust difference is used. In this time chart, for easy understanding, the difference between the actual gear ratio and the target gear ratio is always constant, and the hydraulic pressure corresponding to the shift feedback thrust difference F (fb) and the torque capacity securing pulley thrust F Description will be made using only the hydraulic pressure corresponding to (f1). Also, changes in the actual gear ratio due to feedback control are not taken into consideration.

  When the shift speed B from time T1 to T2 is smaller than the shift speed C from time T2 to T3, the correction coefficient k2 corresponding to the shift speed is greater than the correction coefficient B from time T1 to T2. It is set smaller than the correction coefficient C up to T3. For this reason, the hydraulic pressure corresponding to the corrected gear ratio feedback pulley thrust difference F (fb) considering the correction coefficient k2 set in FIG. 11 is also from time T1 to time T2 to time T2 to time T3. Becomes larger.

  The flowchart shown in FIG. 13 is a subroutine illustrating another method for calculating the gear ratio feedback pulley thrust difference F (fb) executed in step S4. This calculation method is characterized in that, when calculating the gear ratio feedback pulley thrust difference, correction is performed using the primary pulley rotational speed.

  First, in step S51, the actual gear ratio and the target gear ratio are input and the deviation is calculated. In step S52, a feedback control amount is calculated based on the calculated deviation. In step S53, a gear ratio feedback pulley thrust difference F (fb) is calculated based on the feedback control amount.

  In step S74, the primary pulley rotational speed is read, and the correction coefficient k3 is set based on the primary pulley rotational speed read in step S75. Here, the correction coefficient k3 is set so as to decrease as the read rotation speed increases, and the correction coefficient k3 increases as the rotation speed decreases.

  In step S76, the gear ratio feedback pulley thrust difference F (fb) is multiplied by the correction coefficient k3 set in step S75 to obtain the final speed ratio feedback pulley thrust difference F (fb).

  Thus, by correcting the transmission ratio feedback pulley thrust difference F (fb) using a different rotational speed, the stability of the control system is improved. For example, even when the primary pulley rotational speed changes greatly, The correction by the gear ratio feedback can be optimally reflected.

  The correction coefficients k1, k2, and k3 described so far may be used independently, but may be used in combination, and in that case, they may be used by multiplying each.

  FIG. 14 is a time chart for explaining the operation when the above-described method for calculating the gear ratio feedback pulley thrust difference is used. In this time chart, for easy understanding, the difference between the actual gear ratio and the target gear ratio is always constant, and the hydraulic pressure corresponding to the shift feedback thrust difference F (fb) and the torque capacity securing pulley thrust F Description will be made using only the hydraulic pressure corresponding to (f1). Also, changes in the actual gear ratio due to feedback control are not taken into consideration.

  When the accelerator pedal is depressed at time T1, the input rotational speed A gradually increases at the transmission speed B. As the rotational speed increases, the correction coefficient k3 is gradually set to a smaller value. Therefore, the final transmission ratio feedback pulley thrust difference F (fb) decreases as the input rotational speed increases.

It is the schematic of the V belt type continuously variable transmission which is one form of this invention. FIG. 2 is a system diagram showing a shift control hydraulic circuit and a transmission controller in the same form. 4 is a flowchart illustrating an example of hydraulic control executed by a transmission controller in the same form. 4 is a subroutine illustrating a method for calculating a pulley thrust difference for speed change executed in step S3 of FIG. 4 is a subroutine illustrating a method for calculating a gear ratio feedback pulley thrust difference executed in step S4 of FIG. 3. 5 is a conversion magnification calculation map used in step S22 of FIG. 6 is a shift speed pulley thrust difference calculation map used in step S24 of FIG. It is a time chart which illustrates operation | movement of this form. 4 is a subroutine illustrating another method for calculating a gear ratio feedback pulley thrust difference executed in step S4 of FIG. 3. It is a time chart which similarly illustrates the operation. 4 is a subroutine illustrating another method for calculating a gear ratio feedback pulley thrust difference executed in step S4 of FIG. 3. It is a time chart which similarly illustrates the operation. 4 is a subroutine illustrating another method for calculating a gear ratio feedback pulley thrust difference executed in step S4 of FIG. 3. It is a time chart which similarly illustrates the operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 V belt type continuously variable transmission 2 Primary pulley 2a Fixed flange 2b Movable flange 2c Primary pulley chamber 3 Secondary pulley 3a Fixed flange 3b Movable flange 3c Secondary pulley chamber 4 V belt 5 Engine 11 Transmission control hydraulic circuit 12 Transmission controller 13 Primary Pulley rotation sensor 14 Secondary pulley rotation sensor 16 Accelerator pedal stroke sensor 17 Manual shift switch 17a Inhibitor switch 18 Brake switch 19 Economy mode switch 20 Engine controller 23 Pressure regulator valve 24 Primary pulley side pressure reducing valve 25 Secondary pulley side pressure reducing valve

Claims (9)

A drive pulley thrust generating means for generating a target drive pulley thrust for realizing a target gear ratio by passing a belt between the drive pulley and the driven pulley and sandwiching the belt with the drive pulley;
Driven pulley thrust generating means for generating a target driven pulley thrust for realizing a target gear ratio by sandwiching the belt with the driven pulley;
In a belt type continuously variable transmission comprising a controller for setting the target speed ratio and controlling the driving pulley thrust generating means and the driven pulley thrust generating means,
The controller is
Driving torque capacity securing pulley thrusting means for calculating a driving torque capacity securing pulley thrust that the driving pulley pinches without sliding the belt;
Driving gear ratio holding pulley thrust calculating means for calculating the driving gear ratio holding pulley thrust required to maintain the current actual gear ratio;
Driven torque capacity ensuring pulley thrust calculating means for calculating a driven torque capacity securing pulley thrust that the driven pulley pinches without sliding the belt;
Driven gear ratio holding pulley thrust calculating means for calculating the driven gear ratio holding pulley thrust required to maintain the current actual gear ratio;
A speed change pulley thrust difference calculating means for calculating a target speed change pulley thrust difference required to achieve the target speed change;
Gear ratio feedback pulley thrust difference calculating means for calculating a gear ratio feedback pulley thrust difference in the drive pulley or the driven pulley based on the difference between the target gear ratio and the actual gear ratio;
The shift thrust is obtained by adding the pulley shift difference for the target shift speed and the pulley thrust difference for the gear ratio feedback,
When the shift thrust in the shift direction in which the gear ratio is small is positive,
When the speed change thrust is a positive value, the drive torque capacity securing pulley thrust, the absolute value of the speed change thrust, and the absolute value of the drive speed ratio holding pulley thrust are added to set the target drive pulley thrust. The driven torque capacity securing pulley thrust is the target driven pulley thrust,
When the shift thrust is a negative value, the drive torque capacity securing pulley thrust is set as the target drive pulley thrust, the driven torque capacity securing pulley thrust, the absolute value of the shift thrust, and the driven gear ratio maintaining pulley thrust A target pulley thrust calculating means for setting the target driven pulley thrust by adding an absolute value;
A belt type continuously variable transmission.   2. The belt-type none according to claim 1, wherein the gear ratio feedback pulley thrust difference calculating unit corrects the calculated gear ratio feedback pulley thrust difference based on the driving torque capacity securing pulley thrust. 3. Step transmission.   2. The belt-type continuously variable transmission according to claim 1, wherein the gear ratio feedback pulley thrust difference calculating means corrects the calculated gear ratio feedback pulley thrust difference based on a rotational speed of the drive pulley. transmission.   2. The belt-type continuously variable transmission according to claim 1, wherein the gear ratio feedback pulley thrust difference calculating means corrects the calculated gear ratio feedback pulley thrust difference based on an actual shift speed.   The drive torque capacity securing pulley thrust means calculates a drive torque capacity securing pulley thrust based on a continuously variable transmission input torque, a pulley ratio, and a friction coefficient of oil used in the continuously variable transmission. The belt-type continuously variable transmission according to 1.   6. The belt according to claim 1, wherein the drive speed ratio holding pulley thrust calculation unit calculates a drive speed ratio holding pulley thrust from the drive torque capacity securing pulley thrust, an actual speed ratio, and a pulley ratio. Type continuously variable transmission.   The driven torque capacity securing pulley thrust means calculates a driven torque capacity securing pulley thrust based on a continuously variable transmission input torque, a pulley ratio, and a friction coefficient of oil used in the continuously variable transmission. The belt-type continuously variable transmission according to 1.   8. The belt according to claim 1, wherein the driven gear ratio holding pulley thrust calculating unit calculates a driven gear ratio holding pulley thrust from the driven torque capacity securing pulley thrust, an actual gear ratio, and a pulley ratio. Type continuously variable transmission. A drive pulley thrust generating means for generating a target drive pulley thrust for realizing a target gear ratio by passing a belt between the drive pulley and the driven pulley and sandwiching the belt with the drive pulley;
Driven pulley thrust generating means for generating a target driven pulley thrust for realizing a target gear ratio by sandwiching the belt with the driven pulley;
In a belt type continuously variable transmission comprising a controller for setting the target speed ratio and controlling the driving pulley thrust generating means and the driven pulley thrust generating means,
The controller is
Driving torque capacity securing pulley thrusting means for calculating a driving torque capacity securing pulley thrust that the driving pulley pinches without sliding the belt;
Driving gear ratio holding pulley thrust calculating means for calculating the driving gear ratio holding pulley thrust required to maintain the current actual gear ratio;
A driven torque capacity ensuring pulley thrust calculating means for calculating a driven torque capacity securing pulley thrust that the driven pulley pinches without sliding the belt;
Driven gear ratio holding pulley thrust calculating means for calculating the driven gear ratio holding pulley thrust required to maintain the current actual gear ratio;
A speed change pulley thrust difference calculating means for calculating a target speed change pulley thrust difference required to achieve the target speed change;
Gear ratio feedback pulley thrust difference calculating means for calculating a gear ratio feedback pulley thrust difference in the drive pulley or the driven pulley based on the difference between the target gear ratio and the actual gear ratio;
The shift thrust is obtained by adding the pulley shift difference for the target shift speed and the pulley thrust difference for the gear ratio feedback,
When shifting thrust in the shifting direction that increases the gear ratio is positive,
When the shift thrust is a positive value, the drive torque capacity securing pulley thrust is set as the target drive pulley thrust, and the driven torque capacity securing pulley thrust, the absolute value of the shift thrust, and the driven gear ratio maintaining pulley thrust are Add the absolute value as the target driven pulley thrust,
When the shift thrust becomes a negative value, the target drive pulley thrust is set by adding the drive torque capacity securing pulley thrust, the absolute value of the shift thrust, and the absolute value of the drive speed ratio retaining pulley thrust. Target pulley thrust calculation means for setting the driven torque capacity securing pulley thrust as the target driven pulley thrust ;
A belt-type continuously variable transmission.

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