JP4148796B2 - Control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a control device for a V-belt type continuously variable transmission.
[0002]
[Prior art]
In a V-belt type continuously variable transmission mounted for a vehicle, a V-belt is held between a primary pulley and a secondary pulley that variably control the groove width based on hydraulic pressure, and power is transmitted by the contact friction force. Yes.
[0003]
In such a continuously variable transmission, there is a technique described in Patent Document 1 as a technique for setting the pressure supplied to the primary pulley and the pressure supplied to the secondary pulley at the time of shifting.
[0004]
In this method, first, the target secondary pulley pressure is calculated from the target gear ratio and the input torque, and the target primary pulley pressure is obtained from the target secondary pulley pressure and the target speed. At this time, if the target primary pulley pressure is equal to or lower than a predetermined V belt slip limit pressure, the target secondary pulley pressure is calculated backward from the primary pulley side V belt slip limit pressure. By performing such control, the target gear ratio is achieved without causing slippage of the V-belt.
[0005]
[Patent Document 1]
JP 2000-18347 A
[Problems to be solved by the invention]
However, in the control device for a continuously variable transmission described in Patent Document 1, the target primary pulley pressure and the target secondary pulley pressure are determined based on the determination result of whether the primary pulley or the secondary pulley has the belt slip limit pressure. Therefore, the target primary pulley pressure or the target secondary pulley pressure may change discontinuously. As a result, the change in the gear ratio becomes discontinuous, the smoothness is impaired, and the driver may feel uncomfortable.
[0007]
Therefore, the present invention has been made in view of the above problems, and in a V-belt continuously variable transmission, the target hydraulic pressure of the primary pulley and the secondary pulley is set from the steady hydraulic pressure and the hydraulic pressure for shifting, and the primary pressure is changed during shifting. The object is to prevent the V-belt from slipping by preventing the lower limit torque capacity, which is the slip limit pressure, from being reached.
[0008]
[Means for Solving the Problems]
A first invention includes a primary pulley and a secondary pulley that sandwich a V belt, a primary pulley pressure control valve that controls a hydraulic pressure supplied to the primary pulley, and a secondary pulley pressure control valve that controls a hydraulic pressure supplied to the secondary pulley. A steady hydraulic pressure calculating means for calculating a steady hydraulic pressure capable of achieving the belt torque capacity and the current gear ratio, a target shift speed determining means for determining a target shift speed based on an operating state, and a target shift speed. Shift hydraulic pressure calculating means for calculating possible shift hydraulic pressure, primary pulley pressure setting means for setting the steady hydraulic pressure as a target hydraulic pressure supplied to the primary pulley at the time of downshift, and the steady hydraulic pressure and the shift at the time of downshift. Secondary pulley pressure that sets the oil pressure that is added to the oil pressure as the target oil pressure for the secondary pulley Comprising a constant section, the actual gear ratio calculating means for calculating the actual speed ratio, a target speed ratio setting means for setting a target speed change ratio according to the operating state, wherein the secondary pulley pressure setting means, target during downshifting A hydraulic pressure higher than the minimum hydraulic pressure required to achieve the shift speed is added as the shift hydraulic pressure to the steady hydraulic pressure and set as the target hydraulic pressure of the secondary pulley. The primary pulley pressure setting means Feedback control means for correcting the target hydraulic pressure of the primary pulley so that the actual gear ratio becomes the target gear ratio, and the secondary pulley pressure setting means sets a hydraulic pressure higher than the lowest hydraulic pressure on the secondary pulley side Thus, the feedback control means is configured so that the primary pulley does not easily act in a lower hydraulic pressure direction in which the belt slips. It corrects the target hydraulic pressure.
[0009]
In a second aspect based on the first aspect, the secondary pulley pressure setting means sets a hydraulic pressure higher than the lowest hydraulic pressure as the shift hydraulic pressure only on the downshift side.
A third invention includes a primary pulley and a secondary pulley that hold a V belt, a primary pulley pressure control valve that controls a hydraulic pressure supplied to the primary pulley, and a secondary pulley pressure control valve that controls a hydraulic pressure supplied to the secondary pulley. A steady hydraulic pressure calculating means for calculating a steady hydraulic pressure capable of achieving the belt torque capacity and the current gear ratio, a target shift speed determining means for determining a target shift speed based on an operating state, and a target shift speed. Shift hydraulic pressure calculating means for calculating possible shift hydraulic pressure, primary pulley pressure setting means for adding the steady hydraulic pressure and the shift hydraulic pressure at the time of upshifting to set as a target hydraulic pressure of the primary pulley, and steady hydraulic pressure at the time of upshifting Secondary pulley pressure setting means for setting the secondary pulley target hydraulic pressure, and the actual gear ratio An actual speed ratio calculating means for outputting and a target speed ratio setting means for setting a target speed ratio according to the driving state, and the primary pulley pressure setting means is necessary for achieving the target speed at the time of upshifting. A hydraulic pressure higher than the lowest hydraulic pressure is added as the transmission hydraulic pressure to the steady hydraulic pressure and set as the target hydraulic pressure of the primary pulley, and the secondary pulley pressure setting means sets the actual transmission ratio to the target transmission ratio during upshifting. Feedback control means for correcting the target hydraulic pressure of the secondary pulley as described above, and by setting the hydraulic pressure higher than the lowest hydraulic pressure on the primary pulley side by the secondary pulley pressure setting means, the feedback control means, The target hydraulic pressure of the secondary pulley is corrected so that it does not easily act in the lower hydraulic pressure direction where the belt slips .
According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, the pulley pressure setting means includes a lower limit torque capacity of the belt in which the target hydraulic pressure is calculated from an input torque and an actual speed ratio. It is forbidden to become lower hydraulic pressure.
[0010]
【The invention's effect】
According to the first aspect of the present invention, in the case of a downshift in which the transmission oil pressure is added to the secondary pulley, the target oil pressure of the primary pulley is the oil pressure corrected to the steady oil pressure by the correction amount calculated by the feedback control means . However , the target hydraulic pressure to the secondary pulley is set as a shift hydraulic pressure that is higher than the minimum hydraulic pressure necessary to achieve the target shift speed, and is a hydraulic pressure obtained by adding this shift hydraulic pressure to the steady hydraulic pressure. The actual gear ratio is more likely to be downshifted more than the target gear ratio. Therefore, the correction amount by the feedback control means of the target hydraulic pressure of the primary pulley, to reduce that of the primary pulley oil pressure too much to lower torque capacity direction of the belt, the target hydraulic pressure of the primary pulley of the belt lower torque capacity or it The following is reduced.
[0011]
In the second aspect of the invention , the secondary pulley pressure setting means sets the hydraulic pressure higher than the lowest hydraulic pressure as the shift hydraulic pressure only on the downshift side , so there is no need to keep the line pressure excessively high , resulting in a deterioration in fuel consumption. Can be prevented .
In the third aspect of the invention, in the case of an upshift in which the shift oil pressure is added to the primary pulley, the target oil pressure of the secondary pulley is the oil pressure corrected to the steady oil pressure by the correction amount calculated by the feedback control means. However, the target hydraulic pressure to the primary pulley is set as a shift hydraulic pressure that is higher than the minimum hydraulic pressure necessary to achieve the target shift speed, and is the hydraulic pressure obtained by adding this shift hydraulic pressure to the steady hydraulic pressure. The actual gear ratio is more likely to be upshifted than the target gear ratio. Therefore, the amount of correction by the feedback control means of the target hydraulic pressure of the secondary pulley reduces the hydraulic pressure of the secondary pulley from being excessively applied in the direction of the lower limit torque capacity of the belt, and the target hydraulic pressure of the secondary pulley becomes equal to or lower than the lower limit torque capacity of the belt. The following is reduced.
In the fourth aspect of the invention, since the target hydraulic pressure of the pulley is prohibited from being lower than the lower limit torque capacity of the belt calculated from the input torque and the actual gear ratio, it is possible to reliably prevent the belt from slipping. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1 is a schematic configuration diagram of a V-belt continuously variable transmission, and FIG. 2 is a conceptual diagram of a hydraulic control unit and a CVT control unit.
[0014]
In FIG. 1, a continuously variable transmission 5 is connected to an engine 1 via a torque converter 2 having a lock-up clutch and a forward / reverse switching mechanism 4, and as a pair of variable pulleys, a primary pulley 10 on an input shaft side, an output shaft 13 The pair of variable pulleys 10 and 11 are connected by a V belt 12. The output shaft 13 is connected to the differential 6 via an idler gear 14 and an idler shaft.
[0015]
The transmission ratio of the continuously variable transmission 5 and the contact friction force of the V belt are controlled by a hydraulic control unit 100 that responds to a command from the CVT control unit 20, and the CVT control unit 20 controls an engine 1. The transmission ratio and the contact friction force are determined and controlled based on the input torque information and the output from a sensor or the like which will be described later.
[0016]
A primary pulley 10 of the continuously variable transmission 5 includes a fixed conical plate 10b that rotates integrally with an input shaft, a V-shaped pulley groove that is disposed opposite to the fixed conical plate 10b, and a primary pulley cylinder chamber. The movable conical plate 10a can be displaced in the axial direction by a hydraulic pressure (primary pulley pressure) acting on 10c.
[0017]
The secondary pulley 11 is a fixed conical plate 11b that rotates integrally with the output shaft 13, and is disposed opposite to the fixed conical plate 11b to form a V-shaped pulley groove, and the hydraulic pressure acting on the secondary pulley cylinder chamber 11c. The movable conical plate 11a can be displaced in the axial direction according to (secondary pulley pressure).
[0018]
The driving torque input from the engine 1 is input to the continuously variable transmission 5 via the torque converter 2 and the forward / reverse switching mechanism 4 and transmitted from the primary pulley 10 to the secondary pulley 11 via the V belt 12. The movable conical plate 10a of the tenth and the movable conical plate 11a of the secondary pulley 11 are displaced in the axial direction to change the contact radius with the V-belt 12, thereby continuously changing the gear ratio between the primary pulley 10 and the secondary pulley 11. Can be changed.
[0019]
The transmission ratio of the continuously variable transmission 5 and the contact friction force of the V belt 12 are controlled by the hydraulic control unit 100.
[0020]
As shown in FIG. 2, the hydraulic control unit 100 includes a regulator valve 60 that controls the line pressure, a pressure reducing valve 30 that controls the hydraulic pressure in the primary pulley cylinder chamber 10c (hereinafter referred to as primary pulley pressure), and a secondary pulley cylinder chamber 11c. The pressure reducing valve 61 that controls the supply pressure (hereinafter referred to as secondary pulley pressure) is mainly configured.
[0021]
The line pressure control system is composed of a regulator valve 60 having a solenoid for regulating the pressure oil from the hydraulic pump 80, and is predetermined according to the operation state in accordance with a command (for example, a duty signal) from the CVT control unit 20. The line pressure PL is adjusted.
[0022]
The line pressure PL is supplied to a pressure reducing valve 30 having a solenoid 31 for controlling the primary pressure and a pressure reducing valve 61 having a solenoid 62 for controlling the secondary pressure.
[0023]
The pulley ratio between the primary pulley 10 and the secondary pulley 11 is controlled by the pressure reducing valves 30 and 61 driven in accordance with a shift command signal from the CVT control unit 20, and the line pressure PL supplied to the pressure reducing valves 30 and 61 is adjusted. Then, the primary pressure is supplied to the primary pulley 10 and the secondary pressure is supplied to the secondary pulley 11, and the groove width is variably controlled and set to a predetermined pulley ratio. The pulley ratio is calculated by the ratio of the rotation speed of the primary pulley 10 and the rotation speed of the secondary pulley, and the transmission ratio is a value in consideration of the gear ratio of the idler gear 14 to this pulley ratio.
[0024]
Here, the CVT control unit 20 in FIG. 1 has a primary pulley speed sensor 26 that detects the rotational speed of the primary pulley 10 of the continuously variable transmission 5 and a secondary pulley speed that detects the rotational speed (or vehicle speed) of the secondary pulley 11. The signal from the sensor 27, the shift position from the inhibitor switch 23, the stroke amount from the operation amount sensor 24 (or the opening degree of the accelerator pedal) according to the operation amount of the accelerator pedal operated by the driver, the oil temperature sensor 25, the oil temperature of the continuously variable transmission 5 is read and the gear ratio and the contact friction force of the V-belt 12 are variably controlled.
[0025]
In the CVT control unit 20, the primary pulley rotation speed, the secondary pulley rotation speed (vehicle speed), and the driver's driving intention, for example, the stroke of the accelerator pedal, the presence / absence of the operation of the brake pedal, the travel range, and the shift switch of the manual mode of the transmission A shift control unit 201 that determines a target gear ratio and a target gear speed according to switching, and controls the actual gear ratio toward the target gear ratio, an input torque, a gear ratio, a gear speed, a brake pedal operation state, an accelerator It comprises a pulley pressure (hydraulic pressure) control unit 202 that controls the thrust (contact friction force) of the primary pulley 10 and the secondary pulley 11 according to the stroke amount of the pedal, the shift range, and the like.
[0026]
The pulley pressure control unit 202 determines the target value of the line pressure from the input torque information, the pulley ratio based on the primary pulley rotation speed and the secondary pulley rotation speed, the operation state of the brake, the accelerator pedal stroke amount, and the shift range. The line pressure is controlled by driving the solenoid of 60, the target values of the primary pressure and the secondary pressure are determined, and the solenoids 31, 62 of the pressure reducing valves 30, 61 are driven according to the target values, Primary pulley pressure and secondary pulley pressure are controlled independently. Therefore, it is possible to reliably prevent slippage of the V-belt by controlling the oil pressure of the pulley, which decreases the oil pressure at the time of shifting.
[0027]
Next, an example of the hydraulic pressure control performed by the pulley pressure control unit 202 of the CVT control unit 20 will be described in detail with reference to the flowchart of FIG. The flowchart shown in FIG. 3 and the following is executed every predetermined cycle, for example, every several tens of milliseconds.
[0028]
First, in step S1, the steady pulley thrusts of the primary pulley 10 and the secondary pulley 11 are calculated according to the flowchart shown in FIG. Here, the steady pulley thrust is a torque capacity necessary for achieving the current pulley ratio and holding the V-belt so as not to slip, that is, a hydraulic pressure capable of generating this torque. Next, in step 2, the shift thrust difference between the primary pulley 10 and the secondary pulley 11 is calculated from the flowchart shown in FIG.
[0029]
In step 3, it is determined whether or not the next shift operation calculated by the shift control unit 201 is an upshift. In the case of an upshift, the process proceeds to step 4 to calculate the target thrust (target hydraulic pressure) of the primary pulley 10. In the case of downshift, the routine proceeds to step 6 where the target thrust of the secondary pulley 11 is calculated.
[0030]
The target thrust of the primary pulley 10 calculated in step 4 is calculated as the sum of the primary pulley steady thrust (steady hydraulic pressure) calculated in step 1 and the primary pulley 10 shift thrust (shift hydraulic pressure) calculated in step 2. Is done. In subsequent step 5, the steady thrust of the secondary pulley 11 calculated in step 1 is set as the target thrust of the secondary pulley 11.
[0031]
Similarly, the target thrust of the secondary pulley 11 calculated in step 6 is calculated as the sum of the steady thrust of the secondary pulley 11 calculated in step 1 and the shift thrust of the secondary pulley 11 calculated in step 2. In subsequent step 7, the steady thrust of the primary pulley 10 calculated in step 1 is set as the target thrust of the primary pulley 10.
[0032]
After calculating the target thrust in Steps 5 and 7, the process proceeds to Step 8, where the thrust of the primary pulley 10 is feedback-calculated from the flowchart shown in FIG. 6, and in the subsequent Step 9, the lower limit torque capacity calculated from the input torque and the actual gear ratio. The thrust of the primary pulley 10 (the lower limit torque at which the V-belt does not slip with respect to the pulley) is calculated.
[0033]
Next, at step 10, the larger one of the thrusts of the two primary pulleys 10 calculated at steps 8 and 9 is selected and set as the primary pulley thrust. Further, in step 11, the primary pulley target pressure is calculated by dividing the primary pulley thrust in step 9 by the belt contact area of the primary pulley 10.
[0034]
In step 12, the secondary pulley target pressure calculated by dividing the secondary target thrust calculated in step 5 or 6 by the belt contact area of the secondary pulley 10 is calculated.
[0035]
Next, the calculation of the steady pulley thrust will be described using the flowchart shown in FIG. This calculation is performed by the pulley pressure control unit 202.
[0036]
First, in step 21, the torque input to the primary pulley 10 is calculated. This input torque is the same as the output torque of the engine, but when torque transmission is performed via the torque converter, the torque ratio of the torque converter is considered.
[0037]
In step 22, the target pulley ratio is calculated. The target pulley ratio is calculated from the vehicle speed and the stroke amount of the accelerator pedal. The actual pulley ratio is obtained from the ratio between the rotation speed of the primary pulley 10 and the rotation speed of the secondary pulley.
[0038]
In the subsequent step 23, a thrust map as shown in FIG. 7 is prepared, and the thrust during steady running of each pulley is calculated from the target pulley ratio calculated in step 22. Here, the map for calculating the pulley thrust maps and stores in advance the pulley thrust that can achieve a desired torque capacity and gear ratio.
[0039]
The flowchart shown in FIG. 5 explains the calculation of the shift pulley thrust difference. This calculation is performed by the shift control unit 201 and the pulley pressure control unit 202.
[0040]
In step 31, the shift control unit 201 calculates a target shift speed based on the vehicle speed, shift range, accelerator pedal stroke amount, and the like. The target shift speed is output to the pulley pressure control unit 202. In step 32, the pulley pressure control unit 202 uses a map as shown in FIG. (Movement speed) magnification is calculated.
[0041]
Next, at step 33, the pulley speed is calculated by multiplying the target speed by the pulley speed magnification calculated at the previous step. Further, at step 34, a pulley thrust difference is calculated based on the pulley speed. The pulley thrust difference can be calculated from the map shown in FIG. In this map, the pulley thrust difference is set to be the shift thrust of the secondary pulley at the time of downshift, while it is set to be the shift thrust of the primary pulley at the time of upshift.
[0042]
Further, in this map, the downshift side of the pulley thrust difference, that is, the shift pulley thrust of the secondary pulley, is a predetermined margin or pulley than the pulley thrust difference required to achieve the target shift speed calculated in step 31. The margin rate is set to the added value.
[0043]
FIG. 6 is a flowchart for calculating the thrust of the primary pulley 10 in accordance with the transmission ratio feedback control. This is a feedback correction of the thrust of the primary pulley 10 and is controlled so as to match the target gear ratio, and may be performed by the secondary pulley 11. Therefore, since feedback control is performed so that the transmission gear ratio becomes the target transmission gear ratio, it is possible to shift to the target transmission gear ratio with accuracy. First, in step 41, the target thrust of the primary pulley 10 calculated in step 4 or step 7 is fed. The primary pulley thrust is calculated by forward control. In the subsequent step 42, the deviation between the target pulley ratio and the actual pulley ratio is calculated.
[0044]
In step 43, the previous value of the integral deviation of the transmission system is added to the calculated deviation and set as a new integral deviation. Next, in step 44, the proportional deviation is calculated by multiplying the calculated deviation by the proportional gain of the transmission system, and in step 45, the integral compensation amount is calculated by multiplying the integral deviation set in step 43 by the integral gain.
[0045]
In step 46, the primary pulley thrust calculated in step 41, the proportional compensation amount calculated in step 44, and the integral compensation amount calculated in step 45 are added to calculate the primary pulley thrust. The amount of operation of the pulley can be controlled by calculating the thrust.
[0046]
Steps 42 to 45 are the control contents based on the PI control, but other control laws may be used.
[0047]
Next, the operation of the present invention will be described by taking as an example a downshift that occurs when the accelerator pedal is depressed. When the accelerator pedal is depressed, the supply pressure to the secondary pulley 11 is the target oil pressure obtained by adding the shift thrust to the steady thrust as described above. At this time, the shift thrust is set in advance to a value having a margin for the thrust that can achieve the target shift speed. The supply pressure of the primary pulley 10 is the target oil pressure obtained by adding the feedback compensation amount (proportional compensation amount and integral compensation amount) calculated from the actual gear ratio to the steady thrust, but as described above, Since the supply pressure to the secondary pulley is set with a margin more than the hydraulic pressure that can achieve the target speed, the actual speed ratio tends to be slightly downshifted slightly from the target speed ratio. As a result, the feedback compensation of the primary pulley target hydraulic pressure reduces excessively the primary pulley 10 hydraulic pressure in the belt slip lower limit hydraulic pressure direction, and the primary pulley 10 hydraulic pressure is equal to or less than the belt slip lower limit hydraulic pressure. Is reduced.
[0048]
Next, effects of the embodiment of the present invention will be described.
(1) When downshifting is performed, the supply pressure of the primary pulley 10 is a target hydraulic pressure obtained by adding a feedback compensation amount (proportional compensation amount and integral compensation amount) calculated from the actual gear ratio to the steady thrust. Although the hydraulic pressure is set, the supply pressure to the secondary pulley is set with a margin more than the hydraulic pressure that can achieve the target speed, so the actual speed ratio is slightly downshifted from the target speed ratio. It has become easier. Therefore, the feedback compensation of the primary pulley target hydraulic pressure reduces the primary pulley hydraulic pressure from being excessively applied in the belt slip lower limit hydraulic pressure direction, and the primary pulley 10 hydraulic pressure becomes the belt slip lower limit hydraulic pressure or lower. Is reduced.
(2) The thrust of the primary pulley is the higher of the steady target thrust and the gear ratio feedback compensation amount or the primary target thrust calculated from the steady thrust, the gear shift thrust and the gear ratio feedback compensation amount and the torque capacity lower limit primary thrust. Since the value is set, slipping of the belt can be surely prevented.
(3) Since the margin for the shift thrust is set only on the town shift side, it is not necessary to keep the line pressure excessively high, and deterioration of fuel consumption can be prevented.
[0049]
Although the embodiment of the present invention has been described above, the configuration of the above embodiment shows an example of the configuration to which the present invention is applied, and the scope of the present invention is not limited to the above configuration.
[0050]
For example, in the embodiment of the present invention, among the shift thrusts that can achieve the target shift speed, the thrust map is set as a thrust with a margin in advance at the time of town shift. Alternatively, the target oil pressure of the secondary pulley may be calculated by setting a thrust correction value and adding the thrust correction value to the shift thrust during the downshift.
[0051]
In addition, since the amount of feedback compensation for the actual gear ratio is added to the target thrust of the primary pulley, the pulley required to achieve the target shift speed by using the shift thrust difference on the town shift side of the pulley thrust difference. It is set to a value obtained by adding a predetermined margin or margin ratio to the thrust difference, but is not limited to this. For example, when adding feedback compensation to the target thrust of the secondary pulley In this case, the shift thrust amount on the upshift side of the pulley thrust difference may be set to a value obtained by adding a predetermined margin or margin ratio to the pulley thrust difference necessary to achieve the target shift speed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a V-belt type continuously variable transmission showing an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a CVT control unit and a hydraulic control unit.
FIG. 3 is a flowchart for setting a pulley target pressure performed by a CVT control unit.
FIG. 4 is a flowchart for similarly calculating a steady pulley thrust.
FIG. 5 is a flowchart for calculating a shifting thrust in the same manner.
FIG. 6 is a flowchart illustrating gear ratio feedback control.
FIG. 7 is an example of a map for calculating pulley thrust from pulley ratio and input torque.
FIG. 8 is a map for calculating a magnification of a pulley speed with respect to a shift speed.
FIG. 9 is a map for calculating a pulley thrust difference from a pulley speed.
[Explanation of symbols]
1 Engine 5 Continuously Variable Transmission 10 Primary Pulley 11 Secondary Pulley 20 CVT Control Unit 21 Engine Control Unit 28 Hydraulic Sensor 30 Pressure Reducing Valve 60 Regulator Valve 61 Pressure Reducing Valve 100 Hydraulic Control Unit

Claims (4)

A primary pulley and a secondary pulley holding the V-belt;
A primary pulley pressure control valve for controlling the hydraulic pressure supplied to the primary pulley;
A secondary pulley pressure control valve for controlling the hydraulic pressure supplied to the secondary pulley;
A steady oil pressure calculating means for calculating a steady oil pressure capable of achieving the belt torque capacity and the current gear ratio;
Target shift speed determining means for determining a target shift speed based on the driving state;
Shift oil pressure calculating means for calculating a shift oil pressure capable of achieving the target shift speed;
During downshift, primary pulley pressure setting means for setting the steady hydraulic pressure as a target hydraulic pressure to be supplied to the primary pulley;
Secondary pulley pressure setting means for setting a hydraulic pressure obtained by adding the steady hydraulic pressure and the shift hydraulic pressure as a target hydraulic pressure of the secondary pulley at the time of downshift;
An actual transmission ratio calculating means for calculating an actual transmission ratio;
A target gear ratio setting means for setting a target gear ratio according to the driving state ,
The secondary pulley pressure setting means adds a hydraulic pressure higher than the minimum hydraulic pressure required to achieve the target shift speed during downshifting as the shift hydraulic pressure to the steady hydraulic pressure, and sets the secondary hydraulic pressure as the target hydraulic pressure of the secondary pulley. ,
The primary pulley pressure setting means has a feedback control means for correcting the target hydraulic pressure of the primary pulley so that the actual gear ratio becomes the target gear ratio during downshifting,
By setting a hydraulic pressure higher than the lowest hydraulic pressure on the secondary pulley side by the secondary pulley pressure setting means, the feedback control means makes the target hydraulic pressure of the primary pulley less likely to act in the lower limit hydraulic pressure direction in which the belt slips. control device for a continuously variable transmission, characterized in that corrected.   2. The continuously variable transmission control device according to claim 1, wherein the secondary pulley pressure setting means sets a hydraulic pressure higher than the lowest hydraulic pressure as the shift hydraulic pressure only on the downshift side. A primary pulley and a secondary pulley holding the V-belt;
A primary pulley pressure control valve for controlling the hydraulic pressure supplied to the primary pulley;
A secondary pulley pressure control valve for controlling the hydraulic pressure supplied to the secondary pulley;
A steady oil pressure calculating means for calculating a steady oil pressure capable of achieving the belt torque capacity and the current gear ratio;
Target shift speed determining means for determining a target shift speed based on the driving state;
Shift oil pressure calculating means for calculating a shift oil pressure capable of achieving the target shift speed;
At the time of upshift, primary pulley pressure setting means for adding the steady hydraulic pressure and the transmission hydraulic pressure and setting as a target hydraulic pressure of the primary pulley;
Secondary pulley pressure setting means for setting the steady hydraulic pressure as a target hydraulic pressure of the secondary pulley at the time of upshift;
An actual transmission ratio calculating means for calculating an actual transmission ratio;
Target gear ratio setting means for setting the target gear ratio according to the driving state;
With
The primary pulley pressure setting means adds a hydraulic pressure higher than a minimum hydraulic pressure necessary to achieve a target shift speed during upshifting to the steady hydraulic pressure as the shift hydraulic pressure, and sets the primary hydraulic pressure as the target hydraulic pressure ,
The secondary pulley pressure setting means has a feedback control means for correcting the target hydraulic pressure of the secondary pulley so that the actual gear ratio becomes the target gear ratio during upshifting,
It said secondary pulley pressure setting By setting the minimum higher than the hydraulic oil pressure to the primary pulley side by means, said feedback control means, said secondary pulley so hardly acts on the lower limit hydraulic Direction belt slips A control device for a continuously variable transmission, wherein the target hydraulic pressure is corrected .   4. The pulley pressure setting means for prohibiting the target hydraulic pressure from becoming lower than a lower limit torque capacity of a belt calculated from an input torque and an actual gear ratio. A control device for a continuously variable transmission according to one of the above.

Images