JP3419301B2 - 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 of a shift control device for a continuously variable transmission adopted in a vehicle or the like.

[0002]

2. Description of the Related Art As a continuously variable transmission used in a vehicle,
Conventionally, there are belt type, toroidal type and the like. In these shift control devices for continuously variable transmissions, a target gear 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 determined gear ratio 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. As such a gear change control device, for example, Japanese Patent Application Laid-Open No. No. 9-79369 is known.

This is done by changing the drive speed of an actuator (eg, step motor) that drives the shift control valve, that is, the control amount per unit time, by feedback control based on the deviation between the target gear ratio and the actual gear ratio. , The gear ratio is changed.

[0004]

However, in the above-mentioned conventional example, even if the shift speed of the continuously variable transmission is a value that can be followed, the drive speed of the actuator for driving the shift control valve is set to a predetermined value. When a command that exceeds the limit value is generated, 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 illegally accumulated. And especially,
Accurate gear shift control may not be performed due to hunting or the like occurring during gear shift with a large change in rotation speed.

Further, in order to suppress the above hunting, the feedback gain can be reduced, but in this case, the feedback followability is lowered, and the response of the gear shift control and the control accuracy are lowered. there were.

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

[0007]

A first aspect of the present invention is a continuously variable transmission in which a gear ratio can be continuously changed by an actuator, and feedback is performed with an input shaft speed or a gear ratio of the continuously variable transmission as a target value. In a shift control device for a continuously variable transmission, which comprises a control means for driving an actuator by control, the control means is a target control amount of the actuator.
And the control amount considering the control speed of the actuator.
Determine the drive speed limit value based on the relationship
And, when the driving speed of the actuator becomes the limit value, to drive the actuators by a target value calculated back from the control amount of the actuator.

In a second aspect based on the first aspect, the control means includes a feedback control means and a 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 by a time constant, and the relationship between the limit value of the drive speed of the actuator and the time constant. In accordance with, the target value is selectively calculated back from the control amount.

[0010]

According to a fourth aspect of the present invention, in the first aspect, the control means includes a feedback control means and a feedforward control means, and the output of the feedforward control means is taken into consideration to calculate the target value backwardly. To do.

[0012]

Therefore, according to the first aspect of the present invention, the gear shift is performed through the actuator by the feedback control with the input shaft speed or the gear ratio of the continuously variable transmission as the target value, and the drive speed of the actuator reaches the limit value. In such a case, since the control is performed by the target value that is calculated back from the control amount of the actuator, the actuator does not exceed the limit value of the driving speed. For example, in the case of performing feedback by PI control, As shown in the example, it is possible to prevent the proportional component of the deviation from becoming unrealizable, and to prevent the incorrect accumulation of the integral component, so that hunting can be reliably prevented. Since it is not necessary to reduce the speed, it is possible to ensure the responsiveness and control accuracy of the shift control. That
The target control amount of the actuator and the actuator
Considering the control speed, the drive speed limit is
By determining the boundary value, the target controlled variable is the limit value of the control speed.
When the value exceeds the
You can drive the eater and prevent hunting etc.
The calculation load can be reduced.

According to the second aspect of the invention, when the target value is obtained by the feedback control and the feedforward control, the feedback control means performs the back-calculation of the target value from the control amount so that the feedforward control amount of the actuator is controlled. 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 calculated backward from the control amount according to the relationship between the limit value of the drive speed of the actuator and the time constant. By doing so, the calculation load can be reduced while preventing hunting and the like.

[0015]

According to a fourth 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 backward calculation of the target value in consideration of the output of the feedforward control means. The responsiveness and control accuracy of the shift control can be ensured while preventing the speed limit value from being exceeded.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An 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 which employs a toroidal type continuously variable transmission 10 as the continuously variable transmission.

The driving force of the engine is input to the continuously variable transmission 10 through a torque converter, and a step motor 61 as an actuator that responds to a command value of the gear shift control controller 2 is continuously variable through a hydraulic control device. Machine 10
Is continuously controlled.

The continuously variable transmission 10 is of a half toroidal type, and changes the tilt angle θ of the power roller 18c sandwiched between the input / output discs by a hydraulic control device to continuously change gears. 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 for axially driving a trunnion shaft 50a which supports the power roller 18c of the continuously variable transmission 10, as shown in FIG. The step motor 61 is mainly composed of a control valve 60 which supplies pressure oil to the hydraulic cylinder 50 while feeding back an actual gear ratio according to 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 2, and hydraulic pressure is supplied to and discharged from the upper and lower oil chambers 50H and 50L defined by the piston 50P of the hydraulic cylinder 50.

The axial displacement of the trunnion shaft 50a and the displacement around the shaft (= the tilt angle of the power roller 18c, that is, the actual gear ratio RRTO) according to the hydraulic pressure are passed through a tracing mechanism 67 including a link. Is fed back to the sleeve 64 that moves relative to the spool 63, and the hydraulic pressure to the hydraulic cylinder 50 is the driving amount (step number) of the step motor 61 according to the target speed ratio RTO and the tilt angle of the power roller 18c. That is, the gear ratio is adjusted according to the actual gear ratio RRTO, and this gear ratio is uniquely determined according to the drive amount of the step motor 61.

Here, the step motor 61 and the control valve 60 include a rack formed on the spool 63,
The pinion provided on the step motor 61 is meshed and connected, and the position where the end of the spool 63 contacts the stopper 65 is set to be 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 read from a preset shift map according to the operating state. The target input shaft rotation speed RREV is obtained, and the control amount ASTP (the number of steps) according to the target gear ratio RTO and the feedback control amount by the PI control and the 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 flow charts of FIGS.

3 to 5 are subroutines that are executed at predetermined time intervals. FIG. 3 is a signal measuring section for detecting the operating state, and FIG. 4 is a calculation of the actual target gear ratio RTO0 with a primary delay. FIG. 5 shows an outline of a gear change determination unit to perform and a control amount calculation unit that determines a gear ratio according to the detected operating state, and a signal output unit that outputs a control amount of the step motor 61 according to the gear ratio. 6 shows the details of the shift determining unit that constitutes the shift control unit, FIG. 7 shows the details of the control amount calculating unit, and FIG. 8 shows the detailed flow chart of the FB control amount calculating unit that constitutes the control amount calculating unit. Are shown respectively.

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

Then, in step S2, the output shaft speed No is multiplied by the conversion constant A to obtain the vehicle speed VSP, and
The actual gear ratio RRTO is calculated from the ratio between the input shaft speed Nt and the output shaft speed No.

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

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

In step S3, the gear shift determination unit calculates the target input shaft rotation speed map value RREV00 according to the driving state of the vehicle, and then calculates the actual target gear ratio RTO0 from the target input shaft rotation speed RREV with the first delay. .

Then, the gear shift control unit in step S4 performs the feedforward torque shift compensation of the toroidal type continuously variable transmission 10 on the actual target gear ratio RTO0 obtained in step S3, and at the same time, the target gear ratio and the actual gear ratio. After performing feedback compensation based on the deviation of, the control amount ASTP of the step motor 61 is calculated.

The control amount ASTP thus obtained is shown in FIG.
Is output 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 change gears.

Here, the gear shift judging portion constituting the gear shift control portion is constructed as shown in FIG. 6, and first, in step S10.
Then, based on a shift map (not shown), the target input shaft rotation speed map value RR corresponding to the vehicle speed VSP is set using the throttle opening TVO obtained in step S1 as a parameter.
Calculate EV0.

In step S11, the current actual target input shaft rotation speed RREV at the time of the previous control is stored in the previous value RREVold, and in step S12, the predetermined value K1 is substituted for the first-order lag time constant Kr. In step S13, the above 1
Next delay time constant Kr, target input shaft speed map value RREV
0, the actual target input shaft speed RRVold from the previous actual control, which is a first-order lag based on the following formula
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 that the actual target input shaft rotation speed RREV maps. The value gradually increases toward the value RREV0, and the step motor 61 is moved to the target input shaft rotation speed map value RREV0.
Gradually follow to.

Then, in step S14, the actual target input shaft rotational speed RREV is divided by the output shaft rotational speed No to obtain the actual target gear ratio RTO0, and the processing of FIG. 6 is terminated.

Next, the control amount calculator 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, the torque shift compensation gear ratio RTO is obtained based on a preset map or function as shown in FIG.
1 is calculated, and the fluctuation due to the torque shift is added to the actual target gear ratio RTO0. The torque shift compensation is the same as in Japanese Patent Application No. 9-43497 proposed by the applicant of the present application.

Next, at step S22, the feedforward control amount FFSTP corresponding to the torque shift is calculated from the torque shift compensation gear ratio RTO1 by a preset map or function as shown in FIG.

Then, in step S23, the feedback control amount FBSTP is obtained from the deviation between the actual gear ratio RRTO and the actual target gear ratio RTO1 by PI control or the like, and 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), and the target is reached. When the number of steps DSRSTP is smaller than the current control amount ASTP (step S28), the target number of steps DSR is set for each of the control amounts DSTP set in advance.
While decreasing to STP, the target number of steps DSRSTP
Is larger than the current control amount ASTP (step S
26) is a target step number D by increasing the control amount DSTP by a preset control amount DSTP per unit time.
Match SRSTP.

In step S27, if the control amount ASTP to which the preset control amount DSTP is added is larger than the target step number DSRSTP, the process proceeds to step S30 and the target step number DSRSTP is set as the control amount ASTP without change. Similarly, in step S29, the control amount ASTP obtained by subtracting the preset control amount DSTP is subtracted.
However, if it is larger than the target step number DSRSTP, the process proceeds to step S30 and the target step number DSRST.
Let P be the control amount ASTP as it is.

Next, the calculation process of 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 into the target step number DSRSTP, and step S32 is executed.
Current control amount ASTP and target step number DSRSTP
Make a comparison.

That is, when the target step number DSRSTP is smaller than the current control amount, the process proceeds to step S37, the unit control amount DSTP is subtracted from the control amount ASTP, and the subtracted control amount ASTP is 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, when the target step number DSRSTP is larger than the current control amount, the process proceeds to step S33, the unit control amount DSTP is added to the control amount ASTP, and the added control amount ASTP is the target step number DSRST.
If it is larger than P, the routine proceeds to step S35, where the deviation N between the input shaft rotational speed Nt and the actual target input shaft rotational speed RREV is N.
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 driving speed at which the target step number DSRSTP and the control amount ASTP do not become the same value, that is,
When the drive speed of the step motor 61 exceeds the limit value, the process proceeds to step S39, and the actual target input shaft rotation speed RREV is calculated back from the current control amount ASTP.

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

RTO1 = iRTO1 (ASTP) Then, the back-calculated torque shift compensation gear ratio RTO1
Then, based on the estimated input shaft torque Tin obtained in step S2, the actual target gear ratio RTO0 is calculated backward in the direction opposite to the arrow in the map of FIG.

RTO0 = iRTO0 (RTO1, Tin) The actual target gear ratio RTO0 thus obtained is set to the output shaft rotation speed N.
The actual target input shaft rotation speed RREV is calculated back by multiplying it by o.

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

FBSTPp = Nerr × Gp (RRTO, No) FBSTPi = ΣNerr × Gi (RRTO, No) FBSTP = FBSTPp + FBSTPi where FBSTPp is a proportional control amount (number of steps)
FBSTPi represents the integrated 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 stepper motor 6 that has changed gears with the control amount ASTP corresponding to the target number of steps DSRSTP
1, the feedback control is performed by the input shaft rotation speed Nt, and in addition, the input shaft rotation speed bNt = RREV that can be realized from the current control position is calculated back according to the drive limit speed of the step motor 61. 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.

Now, as shown in FIG. 12, when the accelerator pedal is depressed at time ta for acceleration, the actual target input shaft speed RR is increased as the throttle opening TVO increases.
EV is a map value RREV according to the first-order lag constant K1.
Rise towards zero.

At this time, as shown by the broken line in the figure, in the above-mentioned conventional example, the step motor 6 is operated in the section from time ta to time tb.
While the actual target input shaft rotational speed RREV is set so that the controlled variable ASTP of 1 exceeds the limit value of the driving speed, 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 speed RREV which is the target value
Is calculated back from the control amount ASTP, the step motor 6
Since it is regulated so as not to exceed the limit value of the drive speed of 1, the deviation P (proportion) is prevented from becoming unrealizable as in the conventional example, and the deviation i (integration) is incorrect. Since it is possible to prevent such accumulation, it is possible to reliably prevent the occurrence of hunting and the like, and since it is not necessary to reduce the feedback gain, it is possible to secure the responsiveness and control accuracy of the shift control. .

When 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, the above step S3 is performed regardless of the time constant Kr.
It is not necessary to perform the reverse calculation of 9 and the calculation load of the shift control controller 2 can be reduced.

Even when the drive speed limit value of the step motor 61 is low to some extent, the gear shift time constant Kr is set to a sufficiently large value and the actual target input shaft rotation speed RREV is set.
When it is possible to follow the change of the above, it is not necessary to perform the back calculation in the step S39, and the calculation load of the shift control controller 2 can be reduced.
The actual target input shaft rotation speed RREV may be back-calculated from the control amount ASTP according to the magnitude of

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

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

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a continuously variable transmission showing an 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 showing an example of control performed by a shift control controller, showing a signal measuring unit.

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

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

FIG. 6 is a flowchart showing details of a shift determination unit which also constitutes a shift control unit.

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

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

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

FIG. 10 is a map showing the relationship between the target gear ratio RTO0 and the torque shift compensation gear ratio RTO1 with the estimated input shaft torque as a parameter.

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

FIG. 12 is a graph showing a state of gear 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

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-9-250631 (JP, A) JP-A-9-79369 (JP, A) JP-A-8-114260 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (4)

(57) [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 provided with the control means, the control means controls the target control amount of the actuator and
Based on the magnitude relation of the controlled variable considering the control speed of the tuner.
Determining a driving speed limit value of the actuator Zui, when the driving speed of the actuator becomes the limit value,
A shift control device for a continuously variable transmission, characterized in that the actuator is driven by a target value that is calculated back from the control amount of the actuator. 2. The continuously variable transmission according to claim 1, wherein the control means includes a feedback control means and a feedforward control means, and the feedback control means performs the 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 the target value from the control amount according to the relationship between the limit value of the drive speed of the actuator and the time constant. The shift control device for a continuously variable transmission according to claim 1, wherein the shift calculation is performed backward. 4. The control means is a feedback control means.
And feed forward control means
The target value is back-calculated in consideration of the output of the mode control means.
The shift control of the continuously variable transmission according to claim 1, wherein
Your device.