JP3166672B2 - Transmission control device for continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a shift control device for a continuously variable transmission employed in a vehicle or the like.

[0002]

2. Description of the Related Art Conventionally, as a continuously variable transmission mounted on a vehicle, a belt type or toroidal type continuously variable transmission is known, and a shift control valve is driven by an actuator such as a step motor to reduce the hydraulic pressure. The gear ratio is continuously changed based on the gear ratio.

[0003] Such a shift control device is provided with a disturbance compensator so that a predetermined response characteristic is always obtained by suppressing the influence of disturbance or aging applied to the transmission mechanism and the response delay of the step motor. The applicant of the present application has proposed as Japanese Patent Application Nos. 8-144344, 9-89494 and 9-89496.

[0004]

However, in the above-described conventional shift control device for a continuously variable transmission, the drive speed of the step motor = pulse rate P in accordance with the oil temperature of the transmission.
The PS is variably controlled, and the drive speed is set low at low oil temperature when the viscosity of the hydraulic oil becomes large to secure the driving force of the shift control valve, etc., while at high oil temperature, the drive speed is set high to shift. Although the response is improved, the driving amount of the step motor cannot follow the command value at a low oil temperature because the driving speed is low. Then, since the deviation between the command value and the actual drive amount is input to the disturbance compensator as a disturbance, the magnitude of the disturbance becomes larger than the disturbance that actually occurs, and the stability of the control system is impaired. Oscillation may be caused.

Accordingly, the present invention has been made in view of the above-mentioned problems, and the disturbance becomes excessive at a low oil temperature at which the followability of the actuator is reduced while driving the actuator in accordance with the oil temperature of the transmission. And to perform stable control.

[0006]

According to a first aspect of the present invention, there is provided a continuously variable transmission in which a speed ratio is steplessly variably controlled based on a hydraulic pressure.
A speed change control valve driven by an actuator to variably control the oil pressure, target speed ratio setting means for setting a target speed ratio in accordance with an operation state of the vehicle, actual speed ratio detection means for detecting an actual speed ratio, A drive speed control means for controlling the drive speed of the actuator based on at least the oil temperature of the transmission; and a target gear ratio based on a control target time constant calculated from a preset control target model in accordance with the actual gear ratio. Disturbance compensation means for calculating a disturbance compensation amount as an input; drive amount calculation means for calculating a drive amount of the actuator according to the target gear ratio and the disturbance compensation amount; and driving the actuator by the drive amount and the drive speed. A shift control device for a continuously variable transmission, comprising:
An input switch for switching a disturbance compensation input from a target gear ratio to a value corresponding to the position of the actuator when the driving speed is less than a predetermined value; Means.

In a second aspect based on the first aspect, the input switching means includes a constant calculated according to a deviation between a target speed ratio and an actual speed ratio or a constant calculated according to a driving speed. Calculate the disturbance compensation input.

In a third aspect based on the first aspect, the input switching means switches the disturbance compensation input from a value corresponding to the position of the actuator to the target gear ratio, and sets the actual gear ratio to the target gear ratio. This switching is permitted only when the deviation of the gear ratio is less than a predetermined value.

[0009]

Accordingly, the first aspect of the present invention provides that during normal operation in which the drive speed of the actuator is equal to or higher than a predetermined value, disturbance compensation is performed using the target gear ratio as an input so that the actual gear ratio matches the target gear ratio. Next, the actuator drives the shift control valve. On the other hand, when the oil temperature of the continuously variable transmission is low and the load on the actuator is large, the drive speed is reduced to a value less than a predetermined value to secure the drive force. By changing to a value corresponding to the position of the actuator, the driving position of the actuator = actual gear ratio cannot follow the target gear ratio because the driving speed is low, but the disturbance compensation amount is set to a value corresponding to the current position of the actuator. Therefore, the state in which the actual gear ratio cannot follow the target gear ratio is no longer regarded as an increase in disturbance, and the oscillation of the control system due to the increase in the disturbance compensation amount as in the above-described conventional example is reliably performed. Thus, stable disturbance compensation control can be performed.

According to a second aspect of the present invention, the switching of the disturbance compensation input is performed in accordance with the deviation between the target speed ratio and the actual speed ratio in addition to the driving speed, so that the value corresponding to the position of the actuator from the target speed ratio is obtained. And the switching from the value according to the position of the actuator to the target gear ratio can be smoothly performed in both directions.

In the third invention, when the disturbance compensation input is switched from a value corresponding to the position of the actuator to the target gear ratio, the disturbance compensation input is switched only when the deviation between the target gear ratio and the actual gear ratio is smaller than a predetermined value. By permitting the switching, the disturbance compensation input is switched to the target gear ratio only when the deviation of the gear ratio is small, that is, when the target position of the actuator and the actual drive position are almost the same. Since switching is allowed, it is possible to prevent the disturbance compensation input from suddenly switching during disturbance compensation control,
It is possible to improve the stability of the disturbance compensation control.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 7 show an embodiment of the present invention.
FIG. 1 is a schematic configuration diagram of a shift control device of a V-belt type continuously variable transmission, and FIG.
FIG. 3 shows the relationship between the transmission link 67, the step motor 64, and the transmission control valve 63, respectively.

In FIG. 1, a continuously variable transmission 17 includes a primary pulley 16 connected to an engine (not shown) as a pair of variable pulleys, and a secondary pulley 26 connected to a drive shaft. Belt 2
4 are connected.

The speed ratio of the continuously variable transmission 17 (hereinafter, referred to as the speed ratio)
The frictional force of the V-belt 24 is controlled by a hydraulic control valve 3. The hydraulic control valve 3 has a line pressure control means (not shown) for adjusting the line pressure, and a CVT control as shown in FIG. The shift control valve 63 according to the target pulley ratio from the unit 1
Motor 64 as an actuator for driving
Will be installed.

The CVT control unit 1 includes a primary pulley rotation speed sensor 6 for detecting the rotation speed Npri of the primary pulley 16 of the continuously variable transmission 17 and a secondary pulley rotation speed sensor 7 for detecting the rotation speed Nsec of the secondary pulley 26. The signal, the shift mode Mode and the select position from the inhibitor switch 8, and the throttle opening TVO (or the accelerator pedal depression amount) from the throttle opening sensor 5 according to the accelerator pedal depression amount operated by the driver. The oil temperature Tf and the vehicle speed VS of the continuously variable transmission 17 are read from a temperature sensor (not shown).
P is read, and a pulley ratio ip (hereinafter referred to as a reached pulley ratio, and a target value of a pulley ratio that finally shifts from the current pulley ratio = target gear ratio, according to the driving state of the vehicle or the driver's request is given. ) Is variably controlled. In this embodiment, a value obtained by multiplying the secondary rotation speed Nsec by a predetermined constant is read as the vehicle speed VSP.

The V-belt type continuously variable transmission 17 has a torque converter 12 having a lock-up clutch 11 interposed between it and an engine (not shown). The output of the torque converter 12 is a primary pulley 16 as an input shaft. Is transmitted to

The primary pulley 16 has a fixed conical plate 18 that rotates integrally, and is arranged opposite to the fixed conical plate 18 to form a V-shaped pulley groove. It is composed of a movable conical plate 22 that can be displaced in the axial direction by a primary pulley hydraulic pressure).

On the other hand, the secondary pulley 26 is connected to the axle side, and has a fixed conical plate 30 which rotates coaxially and integrally with the secondary pulley 26;
A movable conical plate 3 which is disposed opposite to and forms a V-shaped pulley groove, and which can be displaced in the axial direction according to the hydraulic pressure (line pressure) acting on the secondary pulley cylinder chamber 32.
4

The movable conical plate 22 of the primary pulley 16 and the movable conical plate 34 of the secondary pulley 26 are displaced in the axial direction to change the contact radius with the V-belt 24 so that the primary pulley 16 and the secondary pulley 26 The pulley ratio, ie, the pulley ratio ip, can be changed.

For example, if the width of the V-shaped pulley groove of the primary pulley 16 is reduced, the V
Since the contact radius of the belt 24 is reduced, the pulley ratio can be reduced (the gear ratio is Hi). If the movable conical plate 22 is displaced in the opposite direction, the pulley ratio becomes large (the gear ratio becomes low).

Such shift control for changing the widths of the V-shaped pulley grooves of the primary pulley 16 and the secondary pulley 26 is performed by hydraulic control of the primary pulley cylinder chamber 20, as shown in FIGS. The control is performed by controlling a step motor 64 that drives a shift control valve 63 of the hydraulic control valve 3.

The stepping motor 64 drives the transmission control valve 63 in response to a command from the CVT control unit 1 via the transmission link 67, and adjusts the hydraulic pressure supplied to the cylinder chamber 20 of the primary pulley 16 by adjusting the actual pressure. Control is performed so that the pulley ratio Aip (= actual gear ratio) matches the target pulley ratio ip.

The feedback means mainly composed of the hydraulic control valve 3 and the transmission link 67 is constructed in the same manner as in the conventional example, and the step motor 64 is connected to the pinion 6.
6 and the rack 65 meshes with each other.
Is connected to one end of a transmission link 67 having a predetermined lever ratio. A spool of the transmission control valve 63 is connected to the middle of the transmission link 67, and the movable cone plate 22 constituting the primary pulley 16 is connected to the other end of the link 67.
The feedback member 158 which responds to the axial displacement of.

One end of the feedback member 158 is axially engaged with the outer periphery of the movable conical plate 22, and the rod 60a of the line pressure control valve 60 is connected to a predetermined position. When the speed change link 67 swings according to the relative displacement of the back member 158, the speed change control valve 63 and the line pressure control valve 60 are driven.

The shift control valve 63 controls the hydraulic pressure supplied to the cylinder chamber 20 of the primary pulley 16 in accordance with the displacement of the shift link 67 based on the driving amount (rotational position) of the step motor 64. The line pressure from the line pressure control valve 60 is constantly supplied to the cylinder chamber 32 of the secondary pulley 26.

Therefore, when the actual pulley ratio Aip matches the attained pulley ratio ip based on the displacement of the step motor 64, the speed change link 67 connected to the movable conical plate 22.
Displaces the spool of the shift control valve 63 to maintain the hydraulic pressure in the cylinder chamber 20 and maintain a predetermined ultimate pulley ratio ip.

In FIG. 2, reference numeral 78 denotes a manual valve responsive to the shift lever, 76 denotes a negative pressure diaphragm, 7
7 is a throttle valve which responds to the negative pressure diaphragm 76,
95 is the lowest Low pulley ratio (the lowest Lo speed ratio)
This is a Lo switch that turns on when it is displaced to.

Next, the shift control performed by the CVT control unit 1 will be described with reference to the control conceptual diagrams of FIGS.

The arrival pulley ratio calculation unit 100 calculates the vehicle speed VSP
And the ultimate gear ratio ip is obtained from a map (not shown) on the basis of the operating state such as the throttle opening TVO and the like. On the other hand, the actual pulley ratio calculation unit 101 calculates the actual pulley ratio Aip from the rotation speed Npri of the primary pulley 16 and the rotation speed Nsec of the secondary pulley 26.

The attained speed ratio ip is smoothed by the filter 102 in accordance with the operating state such as the throttle opening TVO and the like, and then input to the following compensator 103.

In the tracking compensator 103, the actual pulley ratio Ai
The target pulley ratio ip that can follow the attained pulley ratio ip with the time constant Tt from the current actual pulley ratio Aip by the time constant Tt set by the target time constant calculation unit 104 based on p and the like.
Calculate _T.

Next, the feedback compensator 105 controls the stepping motor 64 and the control target model 106 of the transmission mechanism.
Is calculated based on the actual pulley ratio Aip,
Command pulley ratio ip in consideration of the dynamic characteristics of the controlled model based on the deviation between target pulley ratio ip _T and actual pulley ratio Aip
_R , and the command pulley ratio ip _R is set to the indicated value limiter 10.
7 is input.

On the other hand, the disturbance compensation amount from the disturbance compensator 108 as shown in FIG. 5 is input to the instruction value limiter 107, and the command pulley ratio ip _R is corrected in accordance with the disturbance compensation amount. The command pulley ratio i is input to the step instruction unit 109 as shown in FIG.
target position DsrSTP of the step motor 64 according to p _R
Is converted to The target position DsrSTP corresponds to the target displacement of the rack 65 shown in FIG.

The target position DsrSTP is calculated as shown in FIG.
The drive speed (pulse rate) P according to the oil temperature Tf of the continuously variable transmission 17 is controlled by the step motor drive unit 110 shown in FIG.
PS and the number of steps STP are set and output to the step motor 64.

Therefore, the attained pulley ratio ip calculated according to the operating state is the target gear shift that can follow the current actual pulley ratio Aip according to the time constant Tt set from conditions such as the operating state. The ratio ip _T is obtained, and the number of steps and the drive speed PPS of the step motor 64 are calculated by a value obtained by adding disturbance compensation to the command pulley ratio ip _{R obtained} by performing feedback compensation on the target speed ratio ip _T.

As shown in FIG. 5, the disturbance compensator 108 mainly includes a model 200 and a filter 201 having inverse characteristics of a controlled object, and an input selector 202 for switching an input to the filter 201. , a constant computing section 203 when calculating the constant T _H time corresponding to the control target time constant Tp of the control object model 106, corrected by the time constant correction portion 204 in accordance with a shift direction (upshift or downshift) The calculation by the inverse characteristic model 200 and the filter 201 is performed according to the time constant T _H and the actual pulley ratio Aip.

The inverse characteristic model 200 and the filter 201 are described in Japanese Patent Application No. 9-894 proposed by the present applicant.
This is the same as the dynamic characteristic compensation control including disturbance compensation as disclosed in Japanese Patent Application No. 94 and Japanese Patent Application No. 9-89496.

On the other hand, an input selection unit 202 for selecting an input to the filter 201 includes a command pulley ratio ip _R from the feedback compensation unit 105 and a step number pulley ratio conversion unit 2.
One of the converted pulley ratios ipSTP obtained in step 05 is switched according to an input switching flag K described later. Note that the step number pulley ratio conversion unit 205 converts the actual step number STP output by the step motor drive unit 110 = the displacement amount of the rack 65 into a converted pulley ratio based on a preset map or the like.

The calculation of the input switching flag K is performed by the switching flag calculation unit 206 which sets the value of the input switching flag K in accordance with the attained pulley ratio ip and the deviation e of the actual pulley ratio Aip, and also drives the step motor. The output is selected by the flag switching switch 207 that switches K = 0 or the output of the switching flag calculation unit 206 according to the driving speed PPS output by the unit 110. The flag changeover switch 207 sends the output of the changeover flag calculation unit 206 to the input selection unit 202 when the driving speed PPS is equal to or higher than a predetermined value (for example, 200 PPS), and when the driving speed PPS is lower than the predetermined value. It is assumed that the input switching flag K = 0.

The switching flag calculation unit 206 sets K = 1 when the absolute value of the deviation e is close to 0, and sets K = 0 when the absolute value of the deviation e exceeds a predetermined value. It is.

Based on the input switch flag K selected by the flag switch 207, the input selector 202 sets the control input u1 to the command pulley ratio ip _R and the control input u2 to the reduced pulley ratio ipSTP. Is determined.

U = K · u1 + (1−K) · u2 (1) Therefore, the control input u is K = 0 when the driving speed PPS is lower than a predetermined value or when the deviation e is large. is in terms of the pulley ratio ipSTP is input to the filter 201, the input command pulley ratio ip _R becomes K = 1 when the drive speed PPS absolute value of a predetermined value or more and the deviation e is less than the predetermined value to filter 201 Is done.

The control input u processed by the filter 201 waits for a delay corresponding to the dead time of the controlled object in the delay circuit 208, and the feedback input to the output of the inverse characteristic model 200 is used as the disturbance compensation amount. It outputs to the indicated value limiter 107.

The command pulley ratio ip _R subjected to disturbance compensation by the command value limiter 107 is the same as the step command unit 1 shown in FIG.
At 09, the target position of the step motor 64 is converted to the target position DsrSTP.

That is, the step instructing unit 109 converts the command pulley ratio ip _R into the number of steps step based on a map or the like set in advance by the converting unit 120, and then performs the hysteresis in the hysteresis setting unit 121 according to the shift direction. Set and output the target position DsrSTP (number of steps).

Then, the step motor drive unit 110
Based on this target position DsrSTP, the number of command steps STP to the step motor 64 is changed to a drive speed PP corresponding to the oil temperature Tf.
Output with S.

The output command step number STP is calculated by subtracting the actual step number ASTP calculated by the counter 131 from the target position DsrSTP.

The drive speed PPS is determined by the drive speed selection section 132, and the drive speed PPS corresponding to the oil temperature Tf of the continuously variable transmission 17 is set based on a preset map or the like in the same manner as in the conventional example. I do. That is, when the oil temperature Tf is low, the driving speed PPS is set low to secure the driving force of the step motor 64, while when the oil temperature Tf is high, the driving speed PPS is set high to improve the responsiveness. Let it. The determined drive speed PPS is the limiter 13
In step 3, after being limited to within the maximum drive speed according to the drive characteristics of the step motor 64, the pulse generation unit 130 outputs the calculated command step number STP to the step motor 64 at the drive speed PPS.

Next, FIGS. 8 to 10 show flowcharts of the above control performed when the CVT control unit 1 is constituted by a microcomputer. 8 shows a main routine of the shift control, FIG. 9 shows a subroutine of the servo control process, and FIG. 10 shows a subroutine of the disturbance compensation input switching unit. These flowcharts are executed at predetermined time intervals, for example, every 10 msec.

In step S1 of FIG. 8, the continuously variable transmission 17
From the primary rotation speed Npri and the secondary rotation speed Ns
ec (= vehicle speed VSP), the throttle opening TVO according to the driver's operation, and the oil temperature Tf of the continuously variable transmission 17 are read. In addition, a signal from the inhibitor switch 8 (for example, a shift mode Mode) is read. Read.

In step S2, a target rotation speed Npri of the primary pulley 16, that is, a target pulley ratio ip is calculated based on a throttle opening TVO and a vehicle speed VSP based on a shift map (not shown). This step S2
Corresponds to the reached pulley ratio calculation unit 100 in the control block diagram of FIG.

In step S3, the time constant T of the step motor 64 according to the current operation state such as acceleration / deceleration is determined.
Calculation of t and Tp is performed. The calculation of the target time constant Tt is similar to that of the target time constant calculator 104, and the control target time constant Tp is calculated similarly to the control target model 106.

In step S4, servo control of the step motor 64 is performed based on the attained pulley ratio ip, the target time constant Tt, and the control target time constant Tp. The servo control processing in step S4 is performed by a subroutine in FIG. 9, and in the control conceptual diagram in FIG.
This is equivalent to a series of processes performed by the step motor drive unit 110.

Next, the servo control process in step S4 is configured as a subroutine in FIG. 9. First, in step S10, the reaching pulley ratio ip obtained in step S2 is smoothed to obtain an excessive gear ratio. Suppress fluctuations.

In step S11, the step motor 64
To compensate for the follow-up performance, the compensation by the target time constant Tt obtained in step S3, performed similarly by feedforward and the followability compensator 103 calculates the target pulley ratio ip _T from reaching pulley ratio ip .

[0057] Then, in step S12, it calculates the command pulley ratio ip _R performs feedback compensation in the same manner as the feedback compensator 105 based on a deviation of the actual pulley ratio Aip and the target pulley ratio ip.

Next, in step S13, similarly to the input selection unit 202 of the disturbance compensator 108, the disturbance compensation input is converted into the command pulley ratio ip _R or the converted pulley ratio ipSTP obtained by converting the actual step number STP into the pulley ratio. After selecting one, the control target time constant Tp and the actual pulley ratio A from the inverse characteristic model 200 and the filter 201 in step S14.
The disturbance compensation amount is calculated from ip. Step S13
The disturbance compensation input switching process is performed by a subroutine of FIG.

In step S15, the command pulley ratio ip _R is compensated for in accordance with the disturbance compensation amount, as in the case of the instruction value limiter 107, and then in step S16, the command pulley ratio ip _R is set in the same manner as in the step instruction unit 109. Convert to the step motor target position DsrSTP.

In step S17, similarly to the step motor drive section 110, the number of steps STP corresponding to the target position DsrSTP at the drive speed PPS corresponding to the transmission oil temperature Tf.
, And outputs a pulse to the step motor 64 to drive the transmission link 67 and the transmission control valve 63.

Next, the details of the disturbance compensation input performed in step S13 will be described in detail with reference to the subroutine of FIG.

First, in step S20, the actual pulley ratio Ai is calculated based on the primary rotation speed Npri and the secondary rotation speed Nsec.
p is calculated, and in step S21, a deviation e between the attained pulley ratio ip and the actual pulley ratio Aip for which feedback compensation has been performed in step S12 is calculated.

In step S22, the input switching flag K is calculated in accordance with the magnitude of the absolute value of the deviation e, similarly to the switching flag calculation unit 206.

On the other hand, in step S23, the counter 1
Actual step number ASTP from 31 to step motor 64
And the actual step number ASTP is read in step S24 in the same manner as in the step number pulley ratio conversion unit 205.
Calculates the reduced pulley ratio ipSTP corresponding to.

Next, in step S25, after reading the current drive speed PPS, it is determined in step S26 whether the drive speed PPS is equal to or higher than a predetermined value C1 (for example, 200 pps). Is Step S27
Then, the process proceeds to step S30 after setting the input switching flag K to 0, and if it is equal to or more than the predetermined value C1, the process proceeds to step S28 to determine whether the value of the input switching flag K calculated in step S22 is 1 or not. Determine whether or not.

If it is determined in step S28 that K = 1, the flow advances to step S29 to perform the disturbance compensation amount calculation in step S14 with the disturbance compensation input u as the command pulley ratio ipR, while if K = 0, The disturbance compensation amount calculation of step S14 is performed using the disturbance compensation input u as the converted pulley ratio ipSTP.

With the above control, when the oil temperature Tf of the transmission is equal to or higher than the predetermined value C1, the commanded pulley ratio ipR is set to the disturbance compensation input u and the inverse characteristic model 200 of the control object and When the drive speed PPS of the step motor 64 is lower than the predetermined value C1 because the transmission oil temperature Tf is low, the converted pulley ratio ipSTP is obtained by converting the disturbance compensation amount input u from the actual step number ASTP. Is the disturbance compensation input u, the driving speed PPS is low, so that the position of the step motor 64 = the actual pulley ratio Aip cannot follow the command pulley ratio ipR, but the disturbance compensation amount is the actual step number AST.
Since P, that is, the current position of the step motor 64 is calculated as a command value, a state in which the actual pulley ratio Aip cannot follow the command pulley ratio ipR is not regarded as an increase in disturbance, as in the conventional example. In addition, it is possible to reliably prevent oscillation of the control system due to an increase in the disturbance compensation amount, and to perform stable disturbance compensation control.

On the other hand, assuming that the disturbance compensation input u is always the converted pulley ratio ipSTP corresponding to the current position of the step motor 64, when the driving speed PPS becomes faster than the predetermined value C1, the response delay of the step motor 64 becomes longer. The shift responsiveness during normal operation in which the transmission oil temperature Tf is increased is added to the disturbance compensation amount, and the shift responsiveness is reduced.

Therefore, the disturbance compensation input u is set to the converted pulley ratio ipSTP at a low oil temperature according to the driving speed PPS corresponding to the oil temperature Tf, while being set to the commanded pulley ratio ipR at the high oil temperature in the same manner as in the prior art. Thus, control stability at low oil temperature can be ensured while preventing a decrease in shift response during normal operation.

Further, the input switching flag K for switching the disturbance compensation input u is calculated in accordance with the absolute value of the deviation e of the actual pulley ratio Aip, as in the switching flag calculation section 206 and step S22, thereby obtaining the deviation e. Is larger than the predetermined value, the disturbance compensation input u is set as the converted pulley ratio ipSTP corresponding to the current position of the step motor 64, and the commanded pulley ratio is set even if the driving speed PPS is higher than the predetermined value C1. While restricting the switching to ipR, while permitting the switching from the converted pulley ratio ipSTP to the command pulley ratio ipR only when the deviation e is less than a predetermined value, the switching of the disturbance compensation input u reduces the deviation e of the pulley ratio. Only when the state, that is, when the actual step number ASTP substantially coincides with the target position DsrSTP, the conversion from the converted pulley ratio ipSTP to the commanded pulley ratio ipR is performed. Because you allow switching of the compensation input u, prevents the disturbance compensation input u that switches rapidly in disturbance compensation control, it is possible to improve the stability of the disturbance compensation control.

[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 diagram of a hydraulic control valve.

FIG. 3 is a schematic view of a main part of a V-belt type continuously variable transmission.

FIG. 4 is a control conceptual diagram of a CVT control unit.

FIG. 5 is a control conceptual diagram of a disturbance compensator.

FIG. 6 is a control conceptual diagram of a step instructing unit.

FIG. 7 is a conceptual diagram of the control of the step motor drive unit.

FIG. 8 is a flowchart illustrating an example of a gear ratio control performed by the CVT control unit.

FIG. 9 is a flowchart of the servo control unit.

FIG. 10 is a flowchart of a disturbance compensation input switching process.

[Explanation of symbols]

 Reference Signs List 1 CVT control unit 6 Primary rotation speed sensor 7 Secondary rotation speed sensor 16 Primary pulley 17 Continuously variable transmission 18 Fixed conical plate 20 Primary pulley cylinder chamber 22 Movable conical plate 24 V belt 26 Secondary pulley 30 Fixed conical plate 32 Secondary pulley cylinder chamber 34 Movable conical plate 63 Shift control valve 64 Step motor 67 Shift link 108 Disturbance compensator 110 Step motor driver 202 Input selector

Continuation of the front page (56) References JP-A-8-17842 (JP, A) JP-A-62-227825 (JP, A) JP-A 8-296708 (JP, A) JP-A 9-210158 (JP) , A) JP-A-9-144823 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40 -63/48

Claims (3)

(57) [Claims] 1. A continuously variable transmission in which a gear ratio is steplessly variably controlled based on a hydraulic pressure, a shift control valve that is driven by an actuator to variably control the hydraulic pressure, and a target shift in accordance with a driving state of the vehicle. Target speed ratio setting means for setting a ratio; actual speed ratio detecting means for detecting an actual speed ratio; driving speed control means for controlling the driving speed of the actuator based on at least the oil temperature of the transmission; Disturbance compensation means for calculating a disturbance compensation amount by inputting a target gear ratio based on a control target time constant calculated according to an actual gear ratio from the controlled object model, and according to the target gear ratio and the disturbance compensation amount. A shift control device for a continuously variable transmission, comprising: drive amount calculating means for calculating a drive amount of the actuator; and drive control means for driving the actuator based on the drive amount and the drive speed. In addition, the position detecting means for detecting the position of the actuator, and the disturbance compensating means, when the driving speed is less than a predetermined value, the disturbance compensation input, from the target gear ratio to a value corresponding to the position of the actuator A shift control device for a continuously variable transmission, comprising input switching means for switching. 2. The apparatus according to claim 1, wherein said input switching means calculates a disturbance compensation input using a constant calculated according to a deviation between a target gear ratio and an actual gear ratio or a constant calculated according to a driving speed. The shift control device for a continuously variable transmission according to claim 1. 3. The input switching means, when switching the disturbance compensation input from a value corresponding to the position of the actuator to a target speed ratio, only when the deviation between the target speed ratio and the actual speed ratio is less than a predetermined value. 3. The shift control device for a continuously variable transmission according to claim 2, wherein switching is permitted.