JP3446613B2 - Transmission control device for toroidal type 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 speed change control device for a toroidal type continuously variable transmission, and more particularly to a method for switching between feedback control and feedforward control according to operating conditions.

[0002]

2. Description of the Related Art As a continuously variable transmission used in a vehicle,
A continuously variable transmission such as a toroidal type has been conventionally known,
As a shift control of such a continuously variable transmission, for example, there is JP-A-7-137885 proposed by the applicant of the present application.

In order to suppress the torque shift generated in the toroidal type continuously variable transmission, the torque shift is corrected by feedforward in addition to the feedback system by PI (proportional / integral) control.

Further, as disclosed in Japanese Patent Laid-Open No. 9-53716, there is also known one which selectively switches between feedback control and feedforward control.

This is because the detection signal of the vehicle speed or the output shaft rotation speed or the input shaft rotation speed used for the shift control of the continuously variable transmission is detected by detecting the pulse by the gear provided on the shaft and the hall element. However, the detected value is incomplete at a low vehicle speed such as after starting when the rotational speed is extremely low, and the accuracy of the gear ratio detection is reduced, so that accurate feedback control cannot be performed.

Therefore, until the reliability of the detection accuracy of the gear ratio can be ensured, the gear shift control is performed by the feedforward, and when the feedforward control is switched to the feedback control, a step is generated in the target value and the gear shift shock is generated. In order to suppress the occurrence, the target value in feedforward control is learned and controlled from the value in feedback control.

[0007]

However, in the case where the torque shift compensation amount is fed forward while the feedback control and the feed forward control are switched as in the conventional example, the feed forward control is switched to the feedback control. In this case, the torque shift compensation by feedforward may become a new disturbance. For example, as shown in FIG.
When the feedforward is switched to the feedback at 0, as shown by the line in the figure, a step occurs in the control amount of the actuator (for example, a step motor) due to a sudden change in the torque shift compensation amount, and as a result, There has been a problem that the gear ratio i suddenly fluctuates, a gear shift shock occurs, and the drivability deteriorates.

The present invention has been made in view of the above problems, and an object thereof is to suppress torque shift during feedforward while suppressing shift shock at the time of control switching between feedforward and feedback. .

[0009]

A first aspect of the present invention is a continuously variable transmission that includes a transmission mechanism that is driven via a hydraulic control mechanism that is connected to an actuator, and that continuously changes the transmission gear ratio. Based on the target value calculation means for calculating the target gear ratio of the continuously variable transmission according to the state, and the deviation between the actual gear ratio and the target gear ratio, the actual gear ratio matches the target gear ratio, Feedback control means for calculating a command value including at least an integral element, torque shift calculating means for calculating a torque shift compensation amount according to an operating state, and a command by feedforward based on the target gear ratio and the torque shift compensation amount An actuator by selectively switching between the feedforward control means for calculating a value and the feedback control means and the feedforward control means based on the operating state In a speed change control device for a toroidal type continuously variable transmission including a control switching means for driving, a torque shift compensation amount value is initially set to the integral value when the feedforward control is switched to the feedback control.
While setting it as the period value,
When switching to the forward mode, the torque shift
The integral value is set as the initial value for the value of the compensation amount .

In a second aspect based on the first aspect, the control switching means selects the feedback control at least when the vehicle speed exceeds a predetermined low vehicle speed, and otherwise feedforward. Select.

[0011]

According to the first aspect of the present invention, when the control is switched from feedforward to feedback, the torque shift compensation amount is set as an initial value in the integral value, so that the step of the compensation amount at the time of control switching is smoothly absorbed. Therefore, it becomes possible to smoothly shift from the feedforward control that performs torque shift compensation to the feedback control that does not perform torque shift compensation.In addition, when the control is switched from feedback to feedforward, the integrated value for the torque shift compensation amount is Since it is set as the initial value, it becomes possible to smoothly absorb the level difference of the compensation amount at the time of switching the control as described above, and to smoothly switch the control.
The drivability of the vehicle equipped with the toroidal type continuously variable transmission can be improved.

The second aspect of the present invention is such that the control is switched at a predetermined value at which the vehicle speed detection accuracy decreases, for example, at a preset low vehicle speed. Therefore, while the control is performed by feedforward, the shift control is switched from feedforward to feedback control in an operating state in which the vehicle speed exceeds a predetermined low vehicle speed, and the step of the compensation amount is smoothly absorbed when switching these controls. Therefore, it becomes possible to smoothly switch the control according to the vehicle speed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments 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 case where a toroidal type is adopted as the continuously variable transmission 10.

The continuously variable transmission 10 is connected to the engine 11 via a torque converter 12 having a lockup mechanism L / U on the input shaft 20 side, while the output shaft side (output disk side) is not shown in the drawing. The toroidal-type continuously variable transmission 10 connected to the wheels has a speed change mechanism and a mechanical feedback mechanism similar to those of the conventional example, and the step motor 4 (actuator) controls the speed change according to a command from the speed change controller 61. Gear shifting is performed by driving a valve (not shown).

The shift control controller 61 is mainly composed of a microcomputer, and has a throttle opening TVO (or an accelerator pedal depression amount) detected by a throttle opening sensor 62 and an output shaft side of the continuously variable transmission 10. The vehicle speed VSP from the provided vehicle speed sensor 63 and the input shaft 20 of the continuously variable transmission 10 detected by the input shaft rotation sensor 64.
The target speed change ratio imap corresponding to the operating state of the vehicle is calculated based on the output shaft speed No obtained by dividing the engine speed Ni and the vehicle speed VSP by a predetermined constant.

In addition to the above detected value, the operation is performed based on the oil temperature Temp of the continuously variable transmission 10 detected by the oil temperature sensor 65 and the line pressure PL of the continuously variable transmission 10 detected by the oil pressure sensor 66. PID control according to the state (proportional, integral,
The respective feedback gains c ₀ , c ₁ and c ₂ of the differential control) are obtained, and a shift command value u (that is, a shift control valve (not shown) is set so that the actual gear ratio of the continuously variable transmission 10 matches the target gear ratio. The number of steps STP for driving is calculated, and the step motor 4 is instructed.

When the vehicle speed sensor 63 has a low detection accuracy, or when the step motor 4 has a low response speed or a low oil temperature or a high oil temperature, the feedforward control drives the step motor to drive the vehicle speed VSP. And oil temperature T
When emp shifts to the feedback condition, the shift control is switched from feedforward to feedback.

The outline of the shift control of the shift control controller 61 is, as shown in FIG. 2, an arrival target gear ratio imap calculated from a throttle opening TVO and a vehicle speed VSP based on a preset map. Calculator 71
A feedback control unit 70 for performing feedback control based on the reached target gear ratio imap, and a feedforward control unit 80 for performing feedforward control, and a control switch 91 for selectively switching between the feedback control and the feedforward control, 92 is provided.

The feedback control unit 70, as shown in FIG. 2, realizes an arbitrary shift response, and a pre-compensator 72 provided before the closed loop of feedback and a pre-compensator 72 from this pre-compensator 72. In addition to the integrator 74 for obtaining the integrated value from the deviation e between the target gear ratio r2 and the actual gear ratio i, the multiplication gain by multiplying the integral gain c0, the proportional gain c1, and the differential gain 2, etc., the Japanese Patent Application proposed by the applicant of the present application. Flat 7-71495
Similarly to the signal No., the observer 73 for obtaining the differential value of the gear ratio or the amount corresponding thereto is mainly configured to output the command value u.

On the other hand, the feedforward control unit 80 is
A drivability determination filter 81 that corrects a target value according to the driving state of the vehicle (for example, the throttle opening TVO, etc.), and a torque shift that calculates a torque shift compensation amount Ts according to the driving state, similar to the conventional example. A compensator 90 and a control switcher 91 for selecting whether to add the torque shift compensation amount Ts to the output of the drivability determination filter 81 or send it to the integrator 74 of the feedback control unit 70 are provided, and the operating state is provided. Is equal to the feedforward condition, the sum of the torque shift compensation amount Ts and the output of the drivability determination filter 81 is sent as the command value u ′.

The command value u from the feedback control unit 70 and the command value u'from the feedforward control unit 80 are arranged before the step conversion unit 75 which converts the command value into the control amount for the step motor 4. Control switch 9
It is switched by 2. In addition, the control switching devices 91 and 9
2 operates synchronously according to the operating state, and when the operating state is feedforward, the control switch 91
Is switched to add the torque shift compensation amount Ts to the output of the drivability determination filter 81, and the control switch 92 selects the command value u ′ of the feedforward control unit 80 as the input of the step conversion unit 75.

On the other hand, when the operating state is feedback, the control switching unit 91 is switched to send the torque shift compensation amount Ts to the integrator 74, and the control switching unit 92 receives the feedback control unit as an input to the step conversion unit 75. The command value u of 70 is selected.

Here, the predistorter 72 is a closed loop transfer function W of feedback control (electronic + mechanical).
(S)

[0025]

[Equation 1]

The above is the case.

However, λ ₁ , λ ₂ , and λ ₃ are predetermined constants representing the poles of the transfer function W (s), and c ₀ and c ₁ are an integral gain and a proportional gain, respectively.

In such a feedback system, the predistorters A1 and A2 that cancel the poles and zeros of the transfer function W (s).
By arranging at the front stage of the closed loop, the shift characteristics can be matched with a so-called reference model, and an arbitrary shift speed can be obtained by changing the parameters of the reference model.

Here, the reference model is

[0030]

[Equation 2]

In this case, the predistorters A1 and A2 are arranged in front of the predistorter A2, which cancels the pole and zero of the transfer function W (s) of the closed loop, and which has a phase advanced from the target dynamic characteristic. The predistorter A is configured by connecting the compensators A1 and first cancels the poles and zeros of the transfer function W (s) of the closed loop.
2

[0032]

[Equation 3]

The characteristics from the target value are set as shown in the above, and the numerator does not have a zero point, and the precompensator output r2
(= Target gear ratio), overshoot of the actual gear ratio i is suppressed.

Then, the predistorter A1 for advancing the phase of the target dynamic characteristic is set by the following equation,

[0035]

[Equation 4]

It becomes possible to match the characteristic (transmission characteristic) of the transfer function W (s) of the closed loop with the reference model of the equation (2), and the actual transmission gear ratio i becomes the target transmission transmission gear ratio imap.
The target gear ratio r2 (transient target value) based on (the target gear ratio to be finally shifted) can be matched.

Here, since the torque shift compensation is not used during the feedback control, when the control is switched from the feedforward to the feedback in order to eliminate the step difference between the command values u and u'when the control is switched. The torque shift compensation amount Ts is input to the integrator 74 and set as the initial value of the integrated value.

Therefore, at the start of the feedback control, the torque shift amount Ts is set as the initial value of the integrated value. It is possible to surely prevent the occurrence of the shift shock as in the conventional example and realize the smooth control switching without generating the step at the time of the control switching as described above.

Next, an example of the control performed by the shift control controller 61 will be described in detail below with reference to the flowchart of FIG. The flowchart of FIG. 3 is executed every predetermined time, for example, every 10 msec.

First, in step S1, the vehicle speed VSP, the oil temperature Temp and the line pressure PL are read from various sensors, and the actual gear ratio i calculated as described above is read. Then, in step S2, the current operating state is Feedback (F / B in the figure) conditions and feedforward (F in the figure)
/ F) The condition is judged.

That is, when the vehicle speed VSP exceeds the predetermined value V1 and the oil temperature Temp exceeds the predetermined value T1, the process proceeds to step 3 and thereafter to execute the feedback control in order to select the feedback control, while the vehicle speed V
Low vehicle speed range where SP is equal to or lower than a predetermined value V1, or oil temperature Tem
When either one of the low temperature regions where p is equal to or less than the predetermined value T1 is satisfied, the process proceeds to step S10 and thereafter to select the feedforward control, and the feedforward control is executed.

In step S3 for performing feedback control, the state of the control switching flag Fch is checked to determine whether the previous control was feedforward. That is,
When the control switching flag Fch is 1, it indicates that the previous control was feedforward, and the control switching flag Fch
When ch is 0, it means that the previous control was feedback, so when Fch = 1, step S
4, the control switching process is performed, while if not, the process proceeds to step S7.

In step S4 for switching the control, the value of the integrator 74 shown in FIG. 2 is set to the torque shift amount Ts from the torque shift compensator 90 of the feedforward controller 80, and then the control is executed in step S5. Switch 9
Commands 1 and 92 to switch to feedback control.

Then, in step S6, based on the vehicle speed VSP, the oil temperature Temp, the actual gear ratio i, and the oil pressure PL read in step S1, the feedback gains c0, c1,
Of c2, a proportional gain c1 and a differential gain c2 excluding the integral gain c0 are calculated.

On the other hand, in step S7 in which the control is not switched, the vehicle speed VSP and the oil temperature T read in step S1 are read.
The feedback gains c0, c1, and c2 are calculated from emp, the actual gear ratio i, and the hydraulic pressure PL based on a preset gain table (not shown).

After obtaining the feedback gain in this way, the control switching flag Fch is set to 0 in step S8, the control command value u is calculated based on each feedback gain in step S9, and then step S10.
Then, the command value u is converted into the step number STP of the step motor 4 and then output.

On the other hand, if it is determined in step S2 that the operating state is feedforward, step S11
Then, it is determined from the state of the control switching flag Fch whether the previous control was feedback, and the control switching flag F
If ch = 0, it indicates that the previous control was feedback, so the process proceeds to step S12 to perform the control switching process.
Proceed to 14.

In step S12 of switching control, the control switching devices 91 and 92 are instructed to switch to feedforward control, and in step S13, the value of the integrator 74 of the feedback control unit 70 is set to the initial value of the torque shift compensation amount Ts. Set to.

On the other hand, step S14 in which control is not switched
Then, the torque shift amount Ts is calculated based on the operating state.

Then, in step S15, the control switching flag Fch is set to 1, and in step S16,
After obtaining the control command value u ′ by the feedforward, the control amount STP of the step motor 4 is calculated in step S10.

Therefore, when the control is switched from feedforward to feedback, the torque shift compensation amount Ts is set as the initial value in the integral value, so that the step difference at the time of control switching is smoothly absorbed as shown by the solid line in FIG. Then, it becomes possible to smoothly shift from the feedforward control that performs the torque shift to the feedback control that does not perform the torque shift, and it is possible to improve the drivability of the vehicle including the toroidal type continuously variable transmission. Of.

When the control is switched from feedback to feedforward, the torque shift compensation amount Ts
Since the integral value is set as the initial value in the above, the step difference at the time of control switching can be smoothly absorbed and the feedback control without torque shift can be smoothly transferred to the feed forward control with torque shift as in the above. Thus, the drivability of the vehicle equipped with the toroidal type continuously variable transmission can be improved.

Although not shown in the figure, the control switching performed in step S2 is provided with means for detecting a failure of a sensor such as the input shaft rotation sensor 64 or the vehicle speed sensor 63, and the failure of these sensors is detected. At times, feedback may be switched to feedforward.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a shift control device for a toroidal type continuously variable transmission according to an embodiment of the present invention.

FIG. 2 is a block diagram of a shift control controller.

FIG. 3 is a flowchart showing an example of control performed by a shift control controller.

FIG. 4 is a conceptual diagram showing an example of a predistorter.

FIG. 5 is a graph showing an example at the time of control switching from feedforward to feedback, showing a relationship between a gear ratio and a control amount and time, a solid line shows the present invention, and a broken line shows a conventional example.

[Explanation of symbols]

4 step motor 10 continuously variable transmission 61 Shift control controller 62 Throttle opening sensor 63 vehicle speed sensor 64 input shaft rotation sensor 65 Oil temperature sensor 66 Oil pressure sensor 70 Feedback control unit 71 Arrival target gear ratio calculation unit 72 Predistorter 73 Observer 74 integrator 75 step converter 80 Feedforward controller 81 Driving ability determination filter 90 Torque shift compensator 91, 92 Control switch

─────────────────────────────────────────────────── --- Continuation of front page (56) References JP-A-9-53716 (JP, A) JP-A-5-240331 (JP, A) JP-A-7-4508 (JP, A) JP-A-8- 326887 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/00-63/38 F16H 15/00 -15/56

Claims (2)

(57) [Claims] Claims: 1. A continuously variable transmission that includes a speed change mechanism that is driven via a hydraulic control mechanism that is connected to an actuator, and that continuously changes the speed ratio; and a continuously variable transmission according to operating conditions. Based on the target value calculation means for calculating the target speed ratio and the deviation between the actual speed ratio and the target speed ratio, the command value is calculated with at least an integral element so that the actual speed ratio matches the target speed ratio. Feedback control means, a torque shift calculation means for calculating a torque shift compensation amount according to an operating state, a feedforward control means for calculating a command value by feedforward based on the target gear ratio and the torque shift compensation amount, Control switching means for driving the actuator by selectively switching between the feedback control means and the feedforward control means based on the operating state. In shift control system for example was toroidal type continuously variable transmission, wherein the time control switching of the feedback from the feedforward, the torque shift compensation amount value to the integral value
While setting as the initial value,
When switching to feed forward, the torque
A shift control device for a toroidal type continuously variable transmission , comprising: a switching initialization means for setting the integral value as the initial value of the shift compensation amount . 2. The toroidal according to claim 1, wherein the control switching means selects the feedback control at least when the vehicle speed exceeds a predetermined value, and selects the feedforward otherwise. Type continuously variable transmission shift control device.