JP3407664B2 - 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 a shift control device for a continuously variable transmission, and more particularly to a shift control device provided with a mechanical feedback system for feeding back an actual gear ratio.

[0002]

2. Description of the Related Art As a continuously variable transmission used in a vehicle,
BACKGROUND ART V-belt type and toroidal type continuously variable transmissions have been conventionally known, and are disclosed in JP-A-58-54262 and JP-A-3.
A toroidal type continuously variable transmission as disclosed in Japanese Patent No. 288062 is known.

As shown in FIG. 11, this is composed of an input / output cone disk arranged coaxially and a pair of power rollers 3, 3 for transferring power by frictional engagement between the input / output cone disks. It is composed of a so-called single-cavity type toroidal transmission unit and a shift control device having an electronic feedback system by PI control in addition to a mechanical feedback system.

In this toroidal type continuously variable transmission 10, the power rollers 3 and 3 are sandwiched and pressed between the input / output cone disks, and the power roller 3 is sheared by an oil film between the power rollers 3 and the input / output cone disks to cause the input / output cone disks to be compressed. Power is transmitted between the disks.

The gear ratio of the toroidal type continuously variable transmission 10 is determined in accordance with the radius of contact between the power roller 3 and the input cone disc and the output cone disc. 11 and is driven by driving trunnions 41, 41 which are displaceable in the O ₃ axial direction and the axial direction of FIG. 11, and the power roller 3 rotates around the axis of the trunnion 41 in accordance with the axial displacement of the trunnion 41. The contact radius with the input / output cone disk is continuously changed by the tilting motion rotating in the direction. The trunnion 41 pivotally supports the power roller 3 via the eccentric shaft 9.

The shift control device will now be described. As shown in FIG. 11, the hydraulic cylinder 6 is provided at the lower end of the trunnion 41 with a piston 6a responsive to the hydraulic pressure supplied to the upper and lower oil chambers 6H and 6L. And these oil chambers 6H,
The shift control valve 5 for supplying hydraulic pressure to the 6L, and the controller 5
The step motor 4 that drives the sleeve 5b of the speed change control valve 5 in accordance with the command from 2 and the displacement of the trunnion 41 in the O ₃ axis direction (vertical direction in FIG. 11) and around the axis are transferred to the spool 5a of the speed change control valve 5. A mechanical feedback system is mainly composed of the recess cam 7 and the feedback link 8 for feedback.

The step motor 4 is rotated by being given a gear shift command value (step number) corresponding to the target gear ratio from the controller, and the sleeve 5b of the gear shift control valve 5 and the sleeve 5b of the spool 5a are rack-and-pinion. It is driven via a mechanism and is displaced from a predetermined neutral position relative to the spool 5a.

The shift control valve 5 has an input port 5d connected to a hydraulic power source 55 such as an oil pump, one communication port 5e being connected to the oil chamber 6L of the hydraulic cylinders 6, 6 and the other communication port 5f being operated hydraulically. The cylinders 6 and 6 are communicated with the oil chambers 6H, respectively. While the spool 5a is connected to the precess cam 7 via the feedback link 8, the sleeve 5b slidable in the axial direction between the outer circumference of the spool 5a and the inner circumference of the valve body 5c is stepped via the rack and pinion. It is driven by the motor 4.

A spool 5 driven by a step motor 4
Due to the displacement of a, both power rollers 3 and 3 move to the piston 6
The oil is displaced in the O ₃ axis direction according to the oil pressure applied to a. At this time, the oil pressure to each piston 6a is supplied so that the opposing power rollers 3 and 3 are displaced in opposite directions. If the power roller 3 of FIG. 3 moves up, the power roller 3 on the right side of the drawing moves down.

The opposing power rollers 3, 3 are
From the neutral position as shown where the axis of rotation O ₁ intersects the axis of rotation O ₂ of the input / output cone disc, the trunnions 41, 4
They are synchronously offset in response to the mutually opposite displacements of 1.

Based on this offset amount in the O ₃ axis direction, both power rollers 3, 3 are the component force from the input / output cone disk, and the swing axis O which is orthogonal to its own rotation axis O _1.
3 (= rotational axis of the trunnion 41) performs a tilting motion to continuously change the frictional contact radii of the power rollers 3 and 3 with respect to the input / output cone disk, thereby achieving continuously variable transmission. it can.

When the shift command value from the controller is achieved by such a continuously variable shift, the offset amount of the power roller 3 in the O ₃ axis direction and the tilt angle (= actual gear ratio, hereinafter tilt angle and gear ratio are Synonyms) for trunnion 4
1, feedback to the spool 5a of the shift control valve 5 via the precess cam 7 and the feedback link 8, the spool 5a returns to the initial neutral position relative to the sleeve 5b, and the hydraulic oil to the oil chambers 6H and 6L is returned. Since the intake and exhaust are blocked, the trunnions 41, 41 are
The rotation axis O _{1 of No.} 3 returns to the neutral position where it intersects the rotation axis O ₂ of the input / output cone disk, thereby maintaining the achievement of the shift command value.

In such a continuously variable transmission 10, since the displacement of the trunnion 41 and the power roller 3 in the O ₃ axis direction is very small (for example, several mm), the trunnion which constitutes the feedback mechanism by the torque transmitted. Four
When part of 1 is deformed, there is a problem that an error occurs with respect to the target gear ratio.

That is, when the torque transmitted by the toroidal type continuously variable transmission rapidly increases, the power roller 3 receives a force in the O ₃ axis direction at the contact point with the input / output cone disk and applies this to the piston 6a. although supported by a hydraulic, the trunnion 41 that has received the stress causes elastic deformation, not completely support the power rollers 3, power roller 3 to move to O ₃ axially, according to the offset amount of the O ₃ axially As a result, tilting motion is caused, and the actual gear ratio changes with respect to the target gear ratio.

Further, in order to control this to a predetermined target gear ratio, the feedback mechanism by the recess cam 7 and the feedback link 8 works, but when the trunnion 41 is deformed as described above, the rotation center of the power roller 3 (axis O). _Since the distance between ₁ ) and the recess cam 7 changes, the gear ratio constantly shifts by this difference.

Such a shift of the gear ratio is called a so-called torque shift, and in order to cancel this torque shift, the mechanical feedback system is canceled by the electronic feedback system based on the deviation between the target gear ratio and the actual gear ratio. The applicant of the present application has proposed Japanese Patent Application Laid-Open No. 8-296722 which provides a cam canceling feedback section for performing accurate control according to a change in the state of a continuously variable transmission.

Further, the applicant of the present application performs feedforward control in anticipation of delay in proportional-plus-integral control (hereinafter referred to as PI control) and deformation of the mechanical feedback system,
Japanese Patent Application Laid-Open No. 8-
It has been proposed as Japanese Patent No. 326887.

Further, even if the torque shift occurs, the maximum Lo (maximum gear ratio) and the maximum Hi (minimum gear ratio) of the cam surfaces of the precess cam 7 are set so that the tilt angle of the power roller 3 does not exceed a predetermined value. The applicant of the present application has proposed a cam profile of the precess cam 7 in which the inclination in the vicinity of the gear ratio is increased as Japanese Patent Application No. 9-193702.

This is as shown in FIG. 12 and FIG.
The cam surface of the precess cam 7 is provided on both sides of the gently inclined portion 17S formed with a predetermined inclination (= gain), and the inclination increases L
The steeply inclined portions 17L and 17H on the o side and the Hi side are formed outside the change points 17a and 17b corresponding to a predetermined tilt angle, and the cam profile changes near the maximum Lo or the maximum Hi.

As shown in FIG. 13, the maximum Lo and the maximum Hi gear ratios are set in the steep slopes 17L and 17H, and when the actual transmission ratio approaches from the gentle slope 17S to the maximum Lo or the maximum Hi, the mechanical ratio is increased. Since the feedback gain of the feedback system sharply increases, the power roller 3 is prevented from exceeding the predetermined tilt range.

As in Japanese Patent Application Laid-Open No. 8-326887, which has an electronic feedback system utilizing integral control, in which the gain of the precess cam 7 is changed, as in Japanese Patent Application No. 9-193702. It was found that the following problems occur when the above are combined.

That is, in order to make the tilt angle of the power roller 3 within a predetermined range, the inclination near the maximum Lo and maximum Hi gear ratio of the precess cam 7 is made into the steep slope portions 17L and 17H to increase the feedback gain. , PI control, etc., an electronic feedback system including an integrator is used, and when the target gear ratio is maximum Hi, the tilt angle enters the steep slope portion 17H from the gentle slope portion 17S beyond the change point 17b. Then, the drive amount of the step motor 4 with respect to the change amount of the tilt angle is increased, and according to the gain of the steep slope portion 17H
The amount of displacement of the sleeve 5b must be increased.

After that, when the target gear ratio changes from the maximum Hi gear ratio to the tilt angle (= gear ratio) corresponding to the change point 17b, the drive amount of the step motor 4 is increased in accordance with the gain of the steep slope portion 17H. Although it has to be set, if the electronic feedback system including an integrator such as PI control does not have a feedback gain capable of following the steep slope portion 17H, or if the driving speed of the step motor 4 reaches the limit, it becomes sharp. When the inclined portion 17H cannot be followed, as shown in FIG. 14, there is a deviation between the target speed ratio (target value) and the actual speed ratio even at time t1 due to the step motor 4 not being able to follow. The integrated value of the deviation during this period is illegally accumulated, and after time t1, overshoot or
There is a problem that hunting occurs and the drivability is deteriorated.

As for overshooting or hunting due to the incorrect integral value, the target gear ratio is set inside the vicinity of the maximum Lo and the maximum Hi, as disclosed in Japanese Patent Laid-Open No. 3-249464, and Japanese Patent Laid-Open No. 3-249464. As described in the publication, by stopping the integration when the vicinity of the upper and lower speed change ratio limits peculiar to the continuously variable transmission is reached, the integration can be stopped before reaching the change points 17a and 17b of the profile of the recess cam 7. Since it is possible, it is possible to suppress the overshoot and the like as described above.

However, as described above, when the torque shift occurs, the relationship between the precess cam 7 and the tilt angle (gear ratio) is, for example, as shown in FIG. Since the cam profile shifts to the position, a predetermined margin is required in anticipation of this shift. However, when the integration is stopped, the region where the steady deviation is left is enlarged due to the PI control not being established, and the effective shift range becomes unclear. It will be narrowed down as necessary. Of course, the target gear ratio is the maximum L
Set to the inside of the vicinity of o and the highest Hi.
Also in the case of Japanese Patent No. 63, the effective shift range is reduced.

Further, as in the above-mentioned Japanese Patent Laid-Open No. 8-296722, in the case of canceling the mechanical feedback system by the cam canceling feedback section, it is premised that the cam profile does not change from that set in advance. As described above, when the torque shift occurs, the relationship between the profile of the recess cam 7 and the gear ratio is deviated, so that there is a problem that the cam canceling feedback does not operate smoothly. Further, the profile of the recess cam 7 and the gear ratio change. The deviation of the ratio relationship also occurs due to an assembly error or the like, and there is a problem that the cam cancellation feedback does not work smoothly depending on the individual difference of the continuously variable transmission.

Therefore, the applicant of the present application filed Japanese Patent Application No. 10-36.
As No. 045, gain of cam offset feedback,
We have proposed a method that follows the error in the gain of the mechanical feedback system due to the profile of the recess cam 7. This allows the integral to be illegally accumulated even if the relationship between the gain of the mechanical feedback system and the gear ratio is deviated. The above-mentioned overshoot and hunting can be prevented without reducing the effective shift range.

[0028]

However, in the above-mentioned Japanese Patent Application No. 10-36045, the gain of the cam canceling feedback also sharply increases from the vicinity of the maximum Lo or the maximum Hi where the feedback gain of the mechanical feedback system rapidly increases. Since the canceling feedback is positive feedback, the gain also increases with the change to the maximum Lo or the maximum Hi. Therefore, when the gain of the cam canceling feedback becomes excessive with respect to the steep inclination of the precess cam 7, the maximum Lo or the maximum Lo or There was a problem that the divergence occurred to the highest Hi side and the control became unstable.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to prevent the divergence of control when a precess cam whose profile changes and to perform smooth shift control.

[0030]

A first aspect of the present invention is a continuously variable transmission for continuously changing a gear ratio via a transmission mechanism driven by an actuator, and a continuously variable transmission according to an operating state. An electronic feedback control means for calculating the target speed ratio and driving the actuator so that the actual speed ratio matches the target speed ratio; a mechanical feedback means for feeding back the actual speed ratio to the speed change mechanism; In a transmission control device for a continuously variable transmission, which comprises a mechanical feedback gain changing means for changing the gain of the mechanical feedback when the ratio is near the maximum gear ratio or the minimum gear ratio, the electronic feedback means is a gain of the mechanical feedback means. The mechanical feedback canceling means to cancel the Maximum back cancellation means is configured to offset the mechanical feedback gain only to the extent that does not exceed the maximum speed ratio or the minimum speed ratio, the actual gear ratio
If the gear ratio or near the minimum gear ratio is exceeded, the actual gear change
Correct the ratio so that it falls within the range of the maximum gear ratio and the minimum gear ratio.
It

[0031]

In a second aspect based on the first aspect, the electronic feedback control means is provided with a control switching means for selectively switching between feedforward control and feedback control according to an operating state. Even when the forward control is selected, the mechanical feedback canceling means cancels the mechanical feedback gain.

In a third aspect based on the second aspect , the electronic feedback control means includes a sensor failure detection means for detecting an operating state, and when a failure of this sensor is detected, The control switching unit selects the feedforward control, and the correction switching unit outputs the actual gear ratio or the actual gear ratio equivalent value in place of the output of the mechanical feedback canceling unit.

In a fourth aspect based on the third aspect , the correction switching means is provided with a filter that absorbs a step difference when switching the output.

[0035]

Therefore, according to the first aspect of the invention, the mechanical feedback means is set so as to change the feedback gain in the vicinity of the maximum gear ratio or the minimum gear ratio, while the mechanical feedback canceling means of the electronic feedback means is Since the mechanical feedback gain is canceled only in the range where the actual gear ratio does not exceed the maximum gear ratio or the minimum gear ratio, the value of the mechanical feedback canceling means does not exceed the value corresponding to the maximum gear ratio or the minimum gear ratio. Thus, when the mechanical feedback gain increases as in the conventional example, it is possible to reliably prevent the cam canceling feedback from becoming excessive and prevent the divergence of control.

When the actual speed ratio exceeds the maximum speed ratio or the vicinity of the minimum speed ratio, the mechanical feedback canceling means corrects the actual speed ratio so that it falls within the range between the maximum speed ratio and the minimum speed ratio. While preventing the divergence of
The actual gear ratio can be converged to a predetermined gear range.

In the second aspect of the invention, the mechanical feedback gain is canceled by the mechanical feedback canceling means even when the feedback control is switched to the feedforward control according to the operating condition.
It becomes possible to use the maximum gear ratio in which the gain of the mechanical feedback is changed, and the starting performance can be secured.

Further, in the third aspect of the invention, when a failure of the sensor for detecting the operating condition is detected, the gear ratio is controlled by the feedforward control and the mechanical feedback canceling means does not cancel the gear ratio. As a result, the operation can be continued according to the feedforward target value, and failsafe can be secured.

According to the fourth aspect of the invention, when the output from the mechanical feedback canceling means is switched to the actual gear ratio or the value corresponding to the actual gear ratio when the sensor fails, a step is absorbed by the filter. Can be suppressed.

[0040]

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 a single cavity toroidal type similar to the above-mentioned conventional example is adopted as the continuously variable transmission 10, and the present invention is applied to a shift control controller 61 of 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 cone disc 2 side) is shown. Not connected to the drive wheel,
The transmission mechanism and the mechanical feedback mechanism of the toroidal type continuously variable transmission 10 are the same as those shown in the above-mentioned conventional example, and FIG.
The same configuration as that of the conventional example, in which the step motor 4 (actuator) drives the shift control valve 5 in accordance with a command from the shift control controller 61 to shift gears. Will be attached and redundant description will be omitted.

The shift control controller 61 is mainly composed of a microcomputer, and includes a throttle opening TVO detected by the throttle opening sensor 62 and a vehicle speed sensor 63 arranged on the output shaft side of the continuously variable transmission 10. Continuously variable transmission 1 detected by the vehicle speed VSP and the input shaft rotation sensor 64
A target gear ratio corresponding to the operating state of the vehicle is calculated based on the rotational speed Ni of the input shaft 20 of 0, the oil temperature Temp of the continuously variable transmission 10 detected by the oil temperature sensor 65, and the oil pressure PL detected by the oil pressure sensor 66. In addition, the control amount STP such that the actual gear ratio of the continuously variable transmission 10 matches the target gear ratio.
To the step motor 4.

The vehicle speed sensor 63 is obtained by multiplying the output shaft speed No. of the continuously variable transmission 10 by a predetermined constant.
It is output as P.

The outline of the shift control of the shift control controller 61 is, as shown in FIG. 2, the actual speed ratio calculation for obtaining the actual speed ratio i from the vehicle speed VSP (∝output shaft speed No) and the input shaft speed Ni. Based on the deviation of the target gear ratio i * calculated by the target tilt angle calculation unit (not shown) according to the unit 71, the throttle opening TVO and the vehicle speed VSP, and the actual gear ratio i, PID (proportional, integral , Differential) control to perform electronic feedback control to the step motor 4
P is sent out, and the Y displacement estimation unit 72 for estimating the y displacement of the power roller 3, the integrator 74, and the step conversion unit 75.
In addition, the precess cam 7 shown in the above-mentioned conventional example is provided in the inverse function calculating unit 77 and the cam canceling feedback unit 70 that compensate the non-linear relationship between the actual speed ratio i and the power roller 3 to obtain a linear transfer function. The steep slope correction unit 76 that corrects the cam offset feedback gain in the steep slope units 17L and 17H is mainly used to perform multiplication of various gains and addition / subtraction of various signals.

First, the actual gear ratio calculating section 71 calculates the input shaft rotation speed Ni from the input shaft rotation sensor 64 and the vehicle speed sensor 63.
Output shaft speed N obtained by dividing the vehicle speed VSP from
The actual speed ratio i is calculated from the ratio with
Of the steep slope correction unit 7 provided in the cam canceling feedback 70
6 and the deviation calculation and gain calculation unit 73
Etc.

The Y displacement estimator 72, for example, similarly to Japanese Patent Application No. 7-71495 proposed by the present applicant, based on the actual speed ratio i and the control output v, the offset amount y (of the power roller 3). After estimating the axial displacement of the trunnion 41), the estimated value is multiplied by the differential gain c ₂ to obtain the output P
ImOut is obtained, and the output P from the target controlled variable represented by the sum of the output from the integrator 74 and the value obtained by multiplying the proportional gain c _1.
The control amount v is obtained by subtracting imOut. The offset amount y may be obtained from the differential value of the tilt angle φ of the power roller 3.

In the gain calculating section 73, the gains of the PID control, that is, the integral gain c ₀ and the proportional gain c ₁ , are calculated based on the operating conditions such as the vehicle speed VSP, the actual gear ratio i, the oil temperature Temp, and the line pressure PL. The differential gain c ₂ is obtained in the same manner as in the conventional example.

On the other hand, the target speed ratio i * from the target speed ratio calculating unit (not shown) and the actual speed ratio i from the actual speed ratio calculating unit 71 are shown.
The deviation is calculated from, and this deviation is input to the integrator 74. Then, the target value is obtained by adding the value obtained by multiplying the output of the integrator 74 by the predetermined gain C ₀ and the value obtained by multiplying the deviation by the predetermined gain C ₁ .

The Y displacement estimator 72 is based on the actual gear ratio i and the control output v, for example, in the same manner as in Japanese Patent Application No. 7-71495 proposed by the applicant of the present application, based on the offset amount y (of the power roller 3). After estimating the axial displacement of the trunnion 41), the estimated value is multiplied by the differential gain c ₂ to obtain the output P
ImOut is obtained, and the output P from the target controlled variable represented by the sum of the output from the integrator 74 and the value obtained by multiplying the proportional gain c _1.
The control amount v is obtained by subtracting imOut. The offset amount y may be obtained from the differential value of the tilt angle φ of the power roller 3.

Then, the cam offset feedback gain b from the cam offset feedback section 70 is added to the control amount v.
The value v ′ obtained by adding is input to the inverse function calculation unit 77 that corrects nonlinearity.

Since the relationship between the actual gear ratio i and the tilt angle φ of the power roller 3 is a non-linear relationship i = h (φ), this inverse function h ^-1 (i)
Thus, the tilt angle φ is obtained from the actual gear ratio i, and this is multiplied by the cam ratio a set in the gently inclined portion 17S of the precess cam 7 to obtain the command value u.

Then, in the step converter 75, the linearized command value u is converted into the step number STP of the step motor 4.
Convert to. That is, the displacement amount of the spool 5a of the shift control valve 5 (the opening amount of the input port 5a is adjusted so as to eliminate the deviation between the tilt angle φ corresponding to the target gear ratio i * and the tilt angle corresponding to the actual gear ratio i. ) Is obtained, and the step number STP corresponding to this spool displacement amount is set to the step motor 4
Command to.

Here, the steep inclination correcting section 76 provided in the cam canceling feedback section 70, as shown by the dotted line in FIG.
At the position corresponding to the change points 17a and 17b at which the inclination of the recess cam 7 bends, it is configured so as to follow the steeply inclined portions 17L and 17H and the gently inclined portion 17S of the recess cam 7. Similarly to the above, the smooth curves 17L and 17H and the gentle slope 17 are formed by smooth curves.
S is connected, and after the tilt angle of the power roller 3 enters the steep slope portion 17L or 17H, the cam offset feedback (command gear ratio) is increased or decreased to the preset maximum Lo or maximum Hi. Further, even if the actual speed ratio i increases or decreases to the maximum Lo or maximum Hi side, the command speed ratio is fixed to a predetermined maximum Lo or maximum Hi value.

Therefore, the feedback gain (command gear ratio) from the cam canceling feedback section 70, which is positive feedback, changes only between a predetermined maximum Lo and a maximum Hi, depending on the tilt of the power roller 3. The position of the precess cam 7 is a steep slope portion 17L, 17H.
Even if it goes into, since the value of the cam cancellation feedback exceeds the maximum Lo or the maximum Hi and the correction is not performed, the cam cancellation feedback gain becomes excessive in the steep slope portions 17L and 17H as in the conventional example. It is possible to prevent the divergence of control by reliably preventing

Since the cam canceling feedback is determined by a smooth curve as in the case of the conventional example, there is a case where the profile of the precess cam 7 and the cam canceling feedback amount do not match due to torque shift or assembly error. However, since the error in the cam canceling feedback amount becomes gentle, as in the conventional example,
It is possible to realize stable shift control while suppressing deterioration of control followability due to illegal accumulation of integrated values.

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.

First, in step S1, a value obtained by dividing the input shaft rotation speed Ni detected by the input shaft rotation sensor 64 and the vehicle speed VSP detected by the vehicle speed sensor 63 by a predetermined constant is calculated as an actual gear ratio i.

In step S2, the actual gear ratio i and the above-mentioned FIG.
From the control output v, the displacement of the power roller 3 in the Y-axis direction (see FIG. 11, drive amount of the trunnion 41) is estimated, and the estimated value is multiplied by the differential gain C ₂ to calculate the value PimOut.

In step S3, a value obtained by multiplying an integral value of the deviation e between the target speed ratio i * and the actual speed ratio i (output of the integrator 74 in FIG. 2) by an integral gain C ₀ , and the proportional gain C to the deviation e. _The value obtained by multiplying by ₁ and the value obtained in step S2 are added
The control output v is calculated by subtracting mOut.

On the other hand, in step S4, based on the cam cancellation feedback gain characteristic shown in FIG.
The cam canceling feedback b according to the actual gear ratio i obtained in 1 is calculated.

In step S5, the cam offset feedback b is added to the control amount v to obtain the control amount v ', and in steps S6 and S7, the tilt angle φ is obtained from the inverse function h ^-1 (v'). Then, the product of this and the gain a of the recess cam 7 is calculated as a command value u.

Then, in step S8, the target gear ratio i
The valve displacement amount (opening amount) of the shift control valve 5 is determined so as to eliminate the deviation between the tilt angle φ corresponding to * and the tilt angle φ corresponding to the actual gear ratio i, and the valve displacement amount is handled. The step motor 4 is commanded to specify the number of steps STP to be performed.

By the above control, the object to be followed by the cam canceling feedback section 70 is not the cam surface itself of the recess cam 7, but the canceling error between the mechanical feedback mechanism and the cam canceling feedback b. Therefore, as shown in FIG. By using a gentle curve, the change in the offsetting error can be moderated and the magnitude of the error can be reduced, so that the followability can be improved even with the feedback gain equivalent to that of the conventional example. In addition, the value of the cam offset feedback (command gear ratio in FIG. 4) does not exceed the value of the highest Hi or the highest Lo after entering the steeply inclined portions 17L and 17H of the recess cam 7 and increasing. As described above, it is possible to prevent the divergence of the control due to the excessive gain, and to perform the stable shift control.

FIG. 5 and FIG. 6 show the second embodiment, in which the characteristics of the steep inclination correcting section 76 of the first embodiment are changed, and the other points are the same as those of the first embodiment.

As shown in FIG. 5, the relationship between the commanded gear ratio which is the cam offset feedback and the actual gear ratio i is as follows.
Is between the maximum Lo and the maximum Hi, as in the case of the first embodiment, a straight line along 17S along the gentle slope of the precess cam 7 and a smooth curve corresponding to the steep slopes 17L and 17H. However, when the commanded speed ratio reaches the maximum Lo or the maximum Hi, the value is maintained, but when the actual speed ratio exceeds the maximum Lo, the commanded speed ratio is set to change to the Hi side at a predetermined inclination, Similarly, when the actual gear ratio exceeds the maximum Hi, the command gear ratio is set to change to the Lo side at a predetermined inclination.

That is, as shown by the dotted line in FIG. 5, the command gear ratio in which the actual gear ratio i exceeds the maximum Lo is corrected by the linear correction disclosed in Japanese Patent Laid-Open No. 8-296722. With respect to the characteristic (gain = 1 time), when the actual speed ratio exceeds the maximum Lo, the command speed ratio inclines toward the Hi side at a predetermined angle θ, and conversely, when the actual speed ratio exceeds the maximum Hi, Lo Inclining toward the side at a predetermined angle θ.

Therefore, feedback is added by the amount of the inclination angle θ at which the actual speed ratio i tends to exceed the maximum Lo or the maximum Hi, and the power roller 3 tilts beyond the steep slopes 17L and 17H. While restraining
Similar to the first embodiment, it is possible to prevent the divergence of control and perform smooth shift control.

That is, the correction amount (correction gear ratio) given to the control amount v in FIG. 2 is as shown in FIG. 6, and if the actual gear ratio i is between the highest Lo and the highest Hi, the precess cam 7 is obtained.
In addition to canceling the mechanical feedback gain due to, the actual gear ratio i exceeds the maximum Lo or the maximum Hi, the cam offset feedback suppresses excessive tilting of the power roller 3 and controls even if torque shift or the like occurs. It is possible to prevent the tilt angle φ of the power roller 3 from exceeding the steep slopes 17L and 17H while preventing the divergence of the power roller 3 and improve the stability of the shift control.

FIG. 7 and FIG. 8 show the third embodiment, which has the same structure as that of the first embodiment but has a control switching means 80 for switching between the feedback control and the ford forward control according to the driving condition, and the vehicle speed sensor failure detection. A means 67 and an input rotation sensor failure detecting means 68 are provided, and when either one of them detects a failure, a correction switching means 81 for switching the cam canceling feedback to the output of the steep inclination correcting section 76 to the actual gear ratio i is provided. It is a thing.

First, the control switching means 80 feeds forward when the vehicle speed VSP, the output shaft rotation speed No, or the input shaft rotation speed Ni is unstable when the vehicle speed is unstable, based on the operating state input to the gain calculating section 73. Choose a control and also
Even at low oil temperature when the response speed of the step motor 4 decreases,
In addition to selecting the feedforward control and selecting the feedback control in other cases, if the sensor that detects the rotation signal used for the gear shift control fails, the actual gear ratio i can be accurately calculated. Since this is not possible, feedback control is switched to feedforward control.

On the other hand, when the rotation sensors are normal, the correction switching means 81 selects the cam offset feedback by the steep slope correction section 76 even during the feedforward control,
Even during feedforward control, the steep slope 17L
It is possible to start from the maximum Lo gear ratio using.

Further, when the correction switching means 81 detects an abnormality in each rotation sensor, that is, the output of one of the vehicle speed sensor failure detection means 67 and the input rotation sensor failure detection means 68 becomes 1. In this case, since the feedback control is not established, the use of the steep slope correction unit 76 of the cam canceling feedback unit is stopped, the output of the cam canceling feedback 70 is set as the actual speed ratio i, and the steep slope unit 17L,
The correction of 17H is stopped.

A flow chart of the above control is shown in FIG.
The details will be described below.

First, in step S10, the vehicle speed sensor 6
Vehicle speed VSP from 3 and oil temperature tem from oil temperature sensor 65
p, the hydraulic pressure PL from the hydraulic pressure sensor 66, and the actual gear ratio i calculated by the actual gear ratio calculation unit 71 are read.

Then, in step S11, vehicle speed sensor failure detection means 67 and input rotation sensor failure detection means 68.
The signal from is read and the sum of these signals is assigned to the variable Fail. The vehicle speed sensor failure detection means 67 and the input rotation sensor failure detection means 68 set the signal to 1 when the failure is detected, and reset the signal to 0 when the failure is normal. Therefore, when the value of the variable Fail is larger than 0, it can be detected that at least one of the sensors has an abnormality.

Next, in step S12, c ₁ = C1Table (VSP, Temp, i, P) is obtained from a table in which each feedback gain is preset based on the signal indicating the operating state read in step S10.
L) c ₀ = C ₀ Table (VSP, Temp, i, P
L) c ₂ = C2Tablel (VSP, Temp, i, P
L) is calculated.

In step S13, it is determined whether or not the value of the variable Fail obtained in step S11 is greater than 0,
It is determined whether or not the vehicle speed sensor 63 and the input shaft rotation sensor 64 have a failure.

If there is no failure, the process proceeds to step S14, while if a failure is determined, the process proceeds to step S17 to select the feedforward control.

In step S14 where the sensor is normal, whether the current operating state is under the predetermined feedback control condition,
That is, it is determined whether the vehicle speed is higher than a predetermined vehicle speed or higher than a predetermined oil temperature, and if the feedback control condition is satisfied, the feedback control is selected in step S15, while if not, the step S16 is performed. Go to and select feedforward control.

Then, the process proceeds to step S18, and the correction switching means 81 is instructed to select the output of the steep inclination correcting portion 76 in order to perform the correction by the cam offset feedback.

On the other hand, if a failure of the rotation sensor is detected in step S13, the feed-forward control is switched to in step S17, and the cam offset feedback by the steep inclination correcting section 76 is stopped, so that the correction switching means 81 is used. To select the actual gear ratio, and the control for one cycle is completed.

Therefore, when the rotation sensor related to the shift control fails, the feedforward control is switched to, the cam offset feedback by the steep inclination correcting section 76 is stopped, and the operation is continued at the feedforward target value. On the other hand, when the rotation sensor is normal, the feedback control and the feedforward control are switched according to the operating state, and even when the feedforward control is selected, the cam offset feedback from the steep slope correction unit 76 is used. , It is possible to start from the maximum Lo gear ratio located on the steeply inclined portion 17L of the precess cam 7, it is possible to ensure the starting performance during feedforward control, and it is possible to ensure failsafe while preventing the divergence of the control. .

A filter (for example, a low-pass filter) (not shown) is provided after the correction switching means 81,
By absorbing the output from the steep inclination correction unit 76 and the step difference at the time of switching the actual gear ratio i, it is possible to suppress an excessive change in the gear ratio when the control is switched when the rotation sensor fails. .

FIGS. 9 and 10 show the fourth embodiment, in which the control switching means 80 of the third embodiment is abolished and feedback control and feedforward control are switched by changing the feedback gain. Others are the same as those in the third embodiment.

The flowchart of FIG. 10 shows step S1.
Of the 0 to S14, except for moving S12, the third
Similar to the flowchart of FIG. 8 of the embodiment, step S
If the vehicle speed sensor 63 or the input shaft rotation sensor 64 is normal in 13, it is determined in step S14 whether the operating condition is in the feedback condition. If the feedback condition is satisfied, the process proceeds to step S12 '. The third
Similar to the embodiment, after calculating each feedback gain and performing the feedback control, step S1
In step 8, the correction switching unit 81 is instructed to select the steep slope correction unit 76.

On the other hand, if the feedback condition is not satisfied, the process proceeds to step S16 ', and only the proportional gain c ₁ is set to 1 and both the integral gain c ₀ and the differential gain c ₂ are set to 0, whereby the feedforward is performed. As control,
Go to step S18.

On the other hand, if the rotation sensor fails, the process proceeds to step S17 ', where only the proportional gain c ₁ is set to 1 and both the integral gain c ₀ and the differential gain c ₂ are set to 0, whereby the feedforward is performed. After the control, the process proceeds to step S19, and the correction switching means 81 is instructed to select the actual gear ratio i.

Thus, even if the control switching means 80 is abolished, it is possible to switch between the feedback control and the feedforward control by changing the feedback gain, and even if the feedforward control is selected, the steep slope correction section 76 outputs The cam offset feedback allows the vehicle to start from the maximum Lo gear ratio located on the steeply inclined portion 17L of the precess cam 7, which enables smooth start during feedforward control and prevents control divergence and secures a failsafe. It can be carried out.

In step S19, the correction switching means 81 may output the actual gear ratio equivalent value (for example, the tilt angle).

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a shift control device for a 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 similarly showing an example of feedback control.

4A and 4B show a relationship between a cam offset feedback gain characteristic performed by a steep slope correction unit and an actual gear ratio, a dotted line indicates the present embodiment, a broken line indicates a conventional example, and a solid line indicates a conventional example in which a gain = 1. .

FIG. 5 shows the second embodiment, showing the relationship between the characteristics of the cam cancellation feedback gain performed in the steep slope correction unit and the actual gear ratio, where the dotted line indicates the present embodiment, the broken line indicates the conventional example, and the solid line indicates A conventional example with a gain of 1 is shown.

FIG. 6 shows the relationship between the actual gear ratio and the corrected gear ratio,
The dotted line indicates the present embodiment, the broken line indicates the conventional example, and the solid line indicates the gain =
1 shows a conventional example.

FIG. 7 is a block diagram of a shift control controller according to the third embodiment.

FIG. 8 is a flowchart similarly showing an example of control.

FIG. 9 is a block diagram of a shift control controller according to the fourth embodiment.

FIG. 10 is a flow chart showing an example of the same control.

FIG. 11 is a vertical sectional view of the toroidal continuously variable transmission.

FIG. 12 is a conceptual view of a precess cam having a steep slope portion, showing a conventional example.

FIG. 13 is a graph showing the relationship between the tilt angle and the height of the recess cam.

FIG. 14 is a graph showing the relationship between the actual gear ratio, the target value (target gear ratio), and the number of step motor steps by the conventional control.

FIG. 15 is a graph showing the relationship between the tilt angle and height when the precess cam is displaced.

[Explanation of symbols]

3 power rollers 4 step motor 5 shift control valve 6 hydraulic cylinder 7 Precessum 8 feedback links 10 continuously variable transmission 17S gentle slope 17H, 17L steep slope 17a, b change point 41 trunnion 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 67 Vehicle speed sensor failure detection means 68 Input rotation sensor failure detection means 70 Cam offset feedback section 71 Tilt angle calculation unit 75 step converter 76 Steep slope correction unit 77 Inverse function calculator 80 Control switching means 81 Correction switching means

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Takeda 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (56) Reference JP-A-11-230319 (JP, A) JP-A-8- 296722 (JP, A) JP 5-26317 (JP, A) JP 3-144161 (JP, A) JP 62-244724 (JP, A) JP 8-296723 (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 F16H 15/00-15/56

Claims (4)

(57) [Claims] 1. A continuously variable transmission for continuously changing a gear ratio via a gear mechanism driven by an actuator, and a target gear ratio of the continuously variable transmission calculated in accordance with an operating state, and an actual gear ratio. Electronic feedback control means for driving the actuator so that the gear ratio matches the target gear ratio, mechanical feedback means for feeding back the actual gear ratio to the speed change mechanism, and the actual gear ratio near the maximum gear ratio or the minimum gear ratio. In a shift control device for a continuously variable transmission, which comprises a mechanical feedback gain changing means for changing the gain of the mechanical feedback, the electronic feedback means has a mechanical feedback canceling means for canceling the gain of the mechanical feedback means. This mechanical feedback offsetting means is To offset the mechanical feedback gain only without exceeding the speed ratio or the minimum speed ratio
The actual gear ratio is close to the maximum gear ratio or the minimum gear ratio.
If it exceeds, the actual gear ratio is the maximum gear ratio and the minimum gear ratio.
A shift control device for a continuously variable transmission, characterized in that correction is performed so as to fall within a ratio range . 2. The electronic feedback control means is
Feed forward control and feed back control depending on the rotation state.
Control switching means for selectively switching between
Even if you select the feed forward control,
Mechanical feedback bar
2. The shift control device for a continuously variable transmission according to claim 1, wherein the shift gain is canceled . 3. The electronic feedback control means comprises
It is equipped with a sensor failure detection unit that detects the rotation state.
If a sensor failure is detected, the control switching means
In addition to selecting more feedforward control,
Instead of the output of the mechanical feedback cancellation means,
The correction switching means for outputting the gear ratio or the actual gear ratio equivalent value
The continuously variable transmission according to claim 2, wherein the continuously variable transmission is provided.
Shift control device. 4. The correction switching means is a stage for switching the output.
A filter for absorbing the difference is provided.
3. A shift control device for a continuously variable transmission according to item 3.