JPH11257480A - Gear shift control device for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure precision of gear shift control and responsiveness while preventing the drive speed of an actuator from being over a limit value. SOLUTION: A continuously variable transmission 10 to continuously vary a change gear ratio by a step motor 61 and a control means to drive an actuator through feedback control in a way that the number of revolutions of an input shaft of the continuously variable transmission 10 or the change gear ratio forms a target value calculates back a target value from a control amount of the step motor and drives the step motor by the target value when the drive speed of the step motor reaches a limit value.

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 Continuously variable transmissions used in vehicles include:
Conventionally, there are a belt type, a toroidal type, and the like. In these continuously variable transmission shift control devices, a target speed ratio or a target input shaft speed is set according to a vehicle speed VSP and a throttle opening TVO (or an accelerator pedal depression amount). The transmission is determined and feedback is performed by PI control (proportional integration control) or the like so that the actual gear ratio matches the target gear ratio. No. 9-79369 is known.

[0003] In this method, the drive speed of an actuator (eg, a step motor) for driving a shift control valve, that is, a control amount per unit time is changed by feedback control based on a deviation between a target gear ratio and an actual gear ratio. , To change the gear ratio.

[0004]

However, in the above-described conventional example, even if the speed of the continuously variable transmission is a value that can be followed, the drive speed of the actuator that drives the speed change control valve remains at a predetermined value. If a command that exceeds the limit value is issued, if feedback control is performed by PI control, the P component (proportional component) of the deviation cannot be realized, and the i component (integral component) is also incorrectly accumulated. And especially,
Hunting or the like may occur during a shift with a large change in the number of revolutions, and accurate shift control may not be performed.

In order to suppress the hunting, the feedback gain can be reduced. However, in this case, there is a problem that the followability of the feedback is reduced and the responsiveness and control accuracy of the shift control are reduced. there were.

The present invention has been made in view of the above problems, and has as its object to secure the accuracy and responsiveness of shift control while preventing the drive speed of an actuator from exceeding a limit value.

[0007]

According to a first aspect of the present invention, there is provided a continuously variable transmission in which a gear ratio can be continuously changed by an actuator, and a feedback of the input shaft speed or the gear ratio of the continuously variable transmission as a target value. And a control means for driving the actuator by control, wherein the control means, when the driving speed of the actuator reaches a limit value, a target value calculated back from the control amount of the actuator when the driving speed of the actuator reaches a limit value. Drives the actuator.

In a second aspect based on the first aspect, the control means includes feedback control means and feedforward control means, and the feedback control means performs back calculation of the target value.

In a third aspect based on the first aspect, the control means includes means for setting a response characteristic of a target value based on a time constant, and the relationship between the limit value of the drive speed of the actuator and the time constant. , The target value is selectively back calculated from the control amount.

In a fourth aspect based on the first aspect, the control means is configured to determine a drive limit speed of the actuator based on a magnitude relationship between a target control amount of the actuator and a control amount in consideration of the control speed of the actuator. Is determined.

In a fifth aspect based on the first aspect, the control means comprises a feedback control means and a feedforward control means, and performs the reverse calculation of the target value in consideration of an output of the feedforward control means. Do.

[0012]

According to the first aspect of the present invention, gear shifting is performed via the actuator by feedback control using the input shaft speed or the gear ratio of the continuously variable transmission as the target value, and the driving speed of the actuator is set to the limit value. In the case of, since the control is performed by the target value calculated backward from the control amount of the actuator, the actuator does not exceed the limit value of the driving speed. As in the example, it is possible to prevent the proportional component of the deviation from becoming unrealizable and prevent the accumulation of the integral component from being incorrectly performed, thereby reliably preventing the occurrence of hunting and the like. Since there is no need to lower the speed, it is possible to ensure the responsiveness and control accuracy of the shift control.

According to a second aspect of the present invention, when a target value is obtained by feedback control and feedforward control, the feedforward control amount is determined by the feedback control means by performing back calculation of the target value from the control amount. It can be set regardless of the drive speed limit value.

According to a third aspect of the present invention, when the response characteristic of the target value is changed by the time constant, the target value is selectively back calculated from the control amount according to the relationship between the limit value of the driving speed of the actuator and the time constant. By doing so, the calculation load can be reduced while preventing hunting and the like.

According to a fourth aspect of the invention, a drive speed limit value is determined from a magnitude relationship between a target control amount of the actuator and a control amount in consideration of the control speed of the actuator.
When the target control amount exceeds the control speed limit value, the actuator can be driven with the target value calculated backward from the control amount, and the calculation load can be reduced while preventing hunting and the like.

According to a fifth aspect of the present invention, when the target value is obtained by the feedback control means and the feedforward control, the control value of the actuator is driven by performing the reverse calculation of the target value in consideration of the output of the feedforward control means. Responsiveness and control accuracy of the shift control can be ensured while preventing the speed from exceeding the limit value.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example in which the present invention is applied to a continuously variable transmission 10 employing a toroidal type continuously variable transmission 10 as a continuously variable transmission.

The driving force of the engine is input to the continuously variable transmission 10 via a torque converter, and a step motor 61 as an actuator responsive to a command value of the transmission control controller 2 is provided with a continuously variable transmission via a hydraulic control device. Machine 10
Is continuously controlled.

The continuously variable transmission 10 is of a half-toroidal type, and performs a continuous shift by changing the tilt angle θ of the power roller 18c held between the input and output disks by a hydraulic control device. be able to.

As shown in FIG. 2, the transmission mechanism and the hydraulic control device of the continuously variable transmission 10 include a hydraulic cylinder 50 that axially drives a trunnion shaft 50a that supports a power roller 18c of the continuously variable transmission 10. And a control valve 60 for supplying pressure oil to the hydraulic cylinder 50 while feeding back the actual gear ratio in accordance with the drive of the step motor 61 and the displacement of the trunnion shaft 50a. The spool 63 is driven in response to a command from the controller 2 to supply and discharge hydraulic pressure to upper and lower oil chambers 50H and 50L defined by a piston 50P of the hydraulic cylinder 50.

The displacement of the trunnion shaft 50a in the axial direction and the displacement around the shaft (= the tilt angle of the power roller 18c, ie, the actual gear ratio RRTO) according to the hydraulic pressure are transmitted via a follower mechanism 67 including a link. Then, the feedback to the sleeve 64 which moves relatively to the spool 63, the hydraulic pressure to the hydraulic cylinder 50 changes the driving amount (the number of steps) of the step motor 61 according to the target speed ratio RTO, and the tilt angle of the power roller 18c. That is, it is adjusted according to the actual speed ratio RRTO, and this speed ratio is uniquely determined according to the drive amount of the step motor 61.

Here, a step motor 61 and a control valve 60 are connected to a rack formed on a spool 63,
The pinion provided on the step motor 61 is meshed and connected, and the position where the end of the spool 63 abuts on the stopper 65 is set as the origin position of the step motor 61.

The shift control controller 2 reads the throttle opening TVO (or accelerator pedal depression amount ACS) and the engine speed Ne from the engine speed sensor 8 in response to the driver's operation of an accelerator pedal (not shown). The input shaft rotation speed Nt detected by the input shaft rotation sensor 6 of the continuously variable transmission 10 and the output shaft rotation speed No detected by the output shaft rotation sensor 7 are read, respectively, and are read from a predetermined shift map in accordance with the operation state. The target input shaft rotation speed RREV is obtained, and a command amount ASTP (step number) corresponding to the target speed ratio RTO, a feedback control amount by PI control or the like, and a feedforward control amount is commanded to the step motor 61 as an actuator. is there.

Next, an example of the shift control performed by the shift control controller 2 will be described in detail below with reference to the flowcharts of FIGS.

FIGS. 3 to 5 show a subroutine executed at predetermined time intervals. FIG. 3 shows a signal measuring section for detecting an operation state, and FIG. 4 shows a calculation of an actual target speed change ratio RTO0 with a primary delay. FIG. 5 shows an outline of a signal output unit for outputting a control amount of the step motor 61 in accordance with the gear ratio, and a control amount calculating unit for determining a gear ratio according to the detected operating state. 6 shows the details of a shift determining unit constituting the shift control unit, FIG. 7 shows details of the control amount calculating unit, and FIG. 8 shows a detailed flowchart of the FB control amount calculating unit constituting the control amount calculating unit. Are respectively shown.

First, in the signal measuring section of FIG.
In step 1, the engine control state is set to the throttle opening TVO and the engine speed Ne by the engine controller 3 as the operating state of the engine.
From the continuously variable transmission 10, the input shaft speed N
The detection signals such as t and the output shaft rotation speed No are read.

In step S2, the vehicle speed VSP is obtained by multiplying the output shaft rotation speed No by the conversion constant A.
The actual speed ratio RRTO is calculated from the ratio between the input shaft speed Nt and the output shaft speed No.

Further, the output torque Te of the engine is obtained from the throttle opening TVO and the engine speed Ne based on a map set in advance, and the torque ratio t (Nt / N) of the torque converter is obtained based on the map set in advance.
The multiplied by e) is calculated as the estimated input shaft torque Tin of the continuously variable transmission 10.

Next, the flow chart of FIG. 4 shows the outline of the shift control performed based on the operating state obtained in steps S1 and S2.

The shift determining unit in step S3 calculates the target input shaft speed map value RREV00 in accordance with the driving state of the vehicle, and then calculates the actual target speed ratio RTO0 from the first-order target input shaft speed RREV. .

Then, the shift control unit in step S4 performs feedforward for the torque shift compensation of the toroidal type continuously variable transmission 10 to the actual target speed ratio RTO0 obtained in step S3, and executes the target speed ratio and the actual speed ratio. After the feedback compensation is performed based on the deviation of the step motor, the control amount ASTP of the step motor 61 is calculated.

The control amount ASTP obtained in this way is shown in FIG.
In step S5, the step motor 61 drives the hydraulic control device to change the tilt angle of the power roller 18c of the toroidal type continuously variable transmission 10 to perform gear shifting.

Here, the shift determining section constituting the shift control section is configured as shown in FIG.
Then, based on a shift map (not shown), using the throttle opening TVO obtained in step S1 as a parameter, a target input shaft rotation speed map value RR corresponding to the vehicle speed VSP.
Calculate EV0.

In step S11, the actual target input shaft rotation speed RREV at the time of the previous control is stored in the previous value RREVold. Then, in step S12, a predetermined value K1 is substituted for a first-order time constant Kr. In step S13, the above 1
Next delay time constant Kr, target input shaft rotation speed map value RREV
0, the actual target input shaft rotation speed RR with a first-order delay from the actual target input shaft rotation speed RREVold at the time of the previous control, based on the following equation:
Calculate EV.

RREV = (RREV0 + RREVold × Kr) / (Kr + 1) (1) Therefore, the relationship between the target input shaft rotation speed map value RREV0 and the actual target input shaft rotation speed RREV is represented by a map of the actual target input shaft rotation speed RREV. The value gradually increases toward the value RREV0, and the stepping motor 61 is moved to the target input shaft rotation speed map value RREV0.
Follow slowly toward.

In step S14, the actual target speed ratio RTO0 is obtained by dividing the actual target input shaft rotational speed RREV by the output shaft rotational speed No, and the processing in FIG. 6 ends.

Next, the control amount calculating section shown in FIG. 7 will be described in detail.

First, in step S21, in order to eliminate the influence of the torque shift generated in the toroidal type continuously variable transmission 10, the actual target gear ratio RTO0 obtained in step S14 and the estimation obtained in step S2 in FIG. From the input shaft torque Tin, as shown in FIG. 10, based on a map or a function set in advance, the torque shift compensation speed ratio RTO is set.
1 is obtained, and the fluctuation due to the torque shift is added to the actual target gear ratio RTO0. The compensation of the torque shift is similar to that of Japanese Patent Application No. 9-43497 proposed by the present applicant.

Next, in step S22, a feedforward control amount FFSTP corresponding to the torque shift is calculated from the torque shift compensation speed ratio RTO1 using a map or a function set in advance as shown in FIG.

Then, in step S23, the feedback control amount FBSTP is obtained from the difference between the actual speed ratio RRTO and the actual target speed ratio RTO1 by PI control or the like. In step S24, the sum of the feedforward control amount FFSTP and the feedback control amount FBSTP is calculated. Target number of steps D
Calculate as SRSTP.

Next, in steps S25 to S30, the control amount ASTP of the step motor 61 is increased or decreased by a predetermined unit time control amount DSTP from the target step number DSRSTP and the current control amount ASTP (step number). If the step number DSRSTP is smaller than the current control amount ASTP (step S28), the control step ASTP is increased by the preset control amount DSTP by the target step number DSR.
While decreasing to STP, target step number DSRSTP
Is larger than the current control amount ASTP (step S
26) is to increase the control amount DSTP by a preset control amount DSTP per unit time from the control amount ASTP and set the target step number D
Match with SRSTP.

In step S27, if the control amount ASTP obtained by adding the preset control amount DSTP is larger than the target step number DSRSTP, the process proceeds to step S30, and the target step number DSRSTP is directly used as the control amount ASTP. Similarly, in step S29, the control amount ASTP obtained by subtracting the preset control amount DSTP
Is larger than the target step number DSRSTP, the process proceeds to step S30, where the target step number DSRST is set.
P is directly used as the control amount ASTP.

Next, the operation of calculating the feedback control amount FBSTP performed in step S23 of FIG. 7 will be described in detail with reference to the flowchart of FIG.

First, in step S31, the feedforward control amount FFSTP obtained in step S22 is substituted for the target step number DSRSTP, and in step S32
Is the current control amount ASTP and the target step number DSRSTP
Is compared.

That is, when the target step number DSRSTP is smaller than the current control amount, the process proceeds to step S37, in which the unit control amount DSTP is subtracted from the control amount ASTP, and the subtracted control amount ASTP is equal to the target step number D.
If it is less than SRSTP, the process proceeds from step S38 to step S35, and normal feedback control is performed.

On the other hand, if the target step number DSRSTP is larger than the current control amount, the routine proceeds to step S33, where the unit control amount DSTP is added to the control amount ASTP, and the added control amount ASTP is equal to the target step number DSRST.
If it is larger than P, the process proceeds to step S35, where the deviation N between the input shaft speed Nt and the actual target input shaft speed RREV is calculated.
After obtaining err, normal feedback control is performed in step S36.

In other cases, that is, when the control amount ASTP is determined at a drive speed at which the target step number DSRSTP and the control amount ASTP do not become the same value,
If the drive speed of the step motor 61 exceeds the limit value, the process proceeds to step S39, and the back calculation of the actual target input shaft rotation speed RREV is performed from the current control amount ASTP.

In this back calculation, first, with the control amount ASTP = the feedforward control amount FFSTP, the torque shift compensation speed ratio RTO1 is back calculated from the map of FIG. 11 as follows.

RTO1 = iRTO1 (ASTP) Then, the inversely calculated torque shift compensation speed ratio RTO1
From the estimated input shaft torque Tin obtained in step S2, the actual target gear ratio RTO0 is calculated backward in the direction shown by the arrow in the map of FIG.

RTO0 = iRTO0 (RTO1, Tin) The output shaft rotation speed N is added to the actual target gear ratio RTO0 thus obtained.
Then, the actual target input shaft rotation speed RREV is inversely calculated as follows by multiplying by o.

RREV = RTO0 × No In the PI control in steps S35 and S36, the actual target input shaft rotation speed RREV and the input shaft rotation speed when the current control amount ASTP (the value indicating the current driving speed) is maintained. N
After calculating the deviation Nerr of t in step S35, the process proceeds to step S36, where the actual speed ratio RRTO obtained in step S2 and the output shaft rotational speed No obtained in step S1.
Then, a proportional gain Gp and an integral gain Gi are obtained from the above, and the feedback control amount FBSTP is calculated as in the following equation.

FBSTPp = Nerr × Gp (RRTO, No) FBSTPi = ΣNerr × Gi (RRTO, No) FBSTP = FBSTPp + FBSTPi where FBSTPp is a proportional control amount (the number of steps).
, And FBSTPi indicates the integral control amount (the number of steps).

Therefore, the feedback loop of the shift control shown in FIGS. 3 to 8 is as shown in FIG.

That is, the stepping motor 6 that has shifted with the control amount ASTP corresponding to the target step number DSRSTP
1 indicates that, in addition to the feedback control being performed based on the input shaft rotation speed Nt, the input shaft rotation speed bNt = RREV achievable from the current control position is inversely calculated according to the drive limit speed of the step motor 61, and the feedback control is performed. The actual target input shaft rotation speed RREV is set so as not to exceed the limit value of the driving speed of the step motor 61.

As shown in FIG. 12, when the accelerator pedal is depressed at time ta to accelerate, the actual target input shaft rotation speed RR is increased as the throttle opening TVO increases.
EV is a map value RREV in accordance with a first-order delay constant K1.
Ascend towards zero.

At this time, as shown by the dashed line in the drawing, in the conventional example, the stepping motor 6 is driven in the section from time ta to tb.
While the actual target input shaft rotation speed RREV is set such that the control amount ASTP of 1 exceeds the drive speed limit value, according to the present invention shown by the solid line in the figure, in the section from time ta to tb, Actual target input shaft rotation speed RREV as target value
Is calculated backward from the control amount ASTP, and the stepping motor 6
Since the drive speed is restricted so as not to exceed the limit value of 1, the P component (proportional component) of the deviation is prevented from becoming unrealizable as in the conventional example, and the i component (integral component) is illegal. Hunting and the like can be reliably prevented, and in addition, since there is no need to reduce the feedback gain, responsiveness and control accuracy of the shift control can be ensured. .

If the drive speed limit value of the step motor 61 is sufficiently faster than the change of the actual target input shaft rotation speed RREV, regardless of the time constant Kr, the above-described step S3 is performed.
9 does not need to be performed, and the calculation load on the shift control controller 2 can be reduced.

Even when the drive speed limit value of the step motor 61 is somewhat low, the shift time constant Kr is set to a sufficiently large value, and the actual target input shaft speed RREV is set.
When the change can be followed, it is not necessary to perform the back calculation in step S39, and the calculation load on the shift control controller 2 can be reduced. Although not shown, the time constant Kr
May be calculated from the control amount ASTP in accordance with the actual target input shaft speed RREV.

In the above-described embodiment, the case where the toroidal type is used as the continuously variable transmission 10 has been described. However, although not shown, even if the V-belt type is used, the same operation and effect as described above can be obtained. be able to.

Further, in the above embodiment, an example in which a step motor is used as an actuator for driving the control valve 60 has been described. However, the present invention is not limited to this, and a servo motor or a hydraulic actuator may be used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a continuously variable transmission showing one embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a relationship between a step motor and a shift control mechanism of a toroidal-type continuously variable transmission.

FIG. 3 is a flowchart illustrating an example of control performed by a shift control controller, illustrating a signal measurement unit.

FIG. 4 is a flowchart showing an example of control, and shows an outline of a shift control unit.

FIG. 5 is a flowchart illustrating an example of control, showing a signal output unit.

FIG. 6 is a flowchart illustrating details of a shift determining unit that also forms the shift control unit.

FIG. 7 is a flowchart showing details of a control amount calculation unit which also forms the shift control unit.

FIG. 8 is a flowchart illustrating details of a control amount calculation unit that also forms the shift control unit.

FIG. 9 is a control block diagram illustrating an outline of shift control.

FIG. 10 is a map showing a relationship between a target speed ratio RTO0 and a torque shift compensation speed ratio RTO1 using an estimated input shaft torque as a parameter.

FIG. 11 is a map showing a relationship between a torque shift compensation speed ratio RTO1 and a feedforward control amount FFSTP of a step motor.

FIG. 12 is a graph showing a state of shifting, showing a relationship between a target step number, a target input shaft rotation speed, a throttle opening TVO and time.

[Explanation of symbols]

 2 Shift control controller 10 Continuously variable transmission 60 Control valve 61 Step motor

Claims (5)

[Claims] 1. A continuously variable transmission capable of continuously changing a gear ratio by an actuator, and control means for driving the actuator by feedback control using an input shaft speed or a gear ratio of the continuously variable transmission as a target value. In the shift control device for a continuously variable transmission, the control means drives the actuator by a target value calculated backward from a control amount of the actuator when the driving speed of the actuator reaches a limit value. Transmission control device for continuously variable transmission. 2. The continuously variable transmission according to claim 1, wherein the control unit includes a feedback control unit and a feedforward control unit, and the feedback control unit performs back calculation of the target value. Control device. 3. The control means includes means for setting a response characteristic of a target value by a time constant, and selectively sets a target value from a control amount according to a relationship between a limit value of a drive speed of the actuator and a time constant. The shift control device for a continuously variable transmission according to claim 1, wherein the shift calculation is performed back. 4. The actuator according to claim 1, wherein the control means determines the drive speed limit value of the actuator based on a magnitude relationship between a target control amount of the actuator and a control amount in consideration of the control speed of the actuator. A shift control device for a continuously variable transmission according to any one of the preceding claims. 5. The apparatus according to claim 1, wherein said control means includes a feedback control means and a feedforward control means, and performs the reverse calculation of the target value in consideration of an output of the feedforward control means. Transmission control device for a step transmission.