JP3161326B2 - Control device for continuously variable automatic 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 control device for an automatic transmission having a continuously variable transmission.

[0002]

2. Description of the Related Art An output of an engine is transmitted to a drive shaft of a vehicle or the like through a fluid transmission device such as a torque converter or a fluid coupling and a continuously variable transmission that continuously changes the output. 2. Description of the Related Art A two-stage automatic transmission is known.

A continuously variable transmission generally applied to this type of automatic transmission includes a pair of variable pulleys on a driving side and a driven side in which a width of a contact pulley with a V-belt is variably controlled based on hydraulic pressure. The gear ratio is changed by controlling the pulley width of each pulley reciprocally by hydraulic pressure. The opening ratio of the shift control valve to each pulley is detected while detecting the operating conditions so that the gear ratio changes according to a predetermined pattern that is predetermined according to operating conditions such as vehicle speed, engine speed, and load. Is controlled by adjusting

[0004]

An automatic transmission having a continuously variable transmission using such a variable hydraulic pulley is conceived for the purpose of improving the acceleration performance, fuel efficiency and comfort of a vehicle. The control system is designed so as to exhibit an appropriate shift response characteristic according to the operating conditions (see JP-A-3-121358, JP-A-59-217047, etc.).

However, in the conventional continuously variable automatic transmission, even if the control system outputs an appropriate gear ratio command value as a target value, the continuously variable transmission does not always show the gear change response as designed, and A problem arises that the control effect cannot be obtained.

[0006] According to the knowledge of the present applicant, the relationship between the hydraulic pressure applied to each variable pulley and the speed ratio is not always proportional, and in addition, the speed ratio changes from a certain speed ratio to a different speed ratio. This is because the dynamic characteristics of the speed ratio at the time of shifting are not uniform because the hydraulic oil flow rate varies depending on the hydraulic pressure applied to the pulley, that is, the speed ratio. Also, in the case where a shift control valve having different characteristics in the upshift (increase) direction and the downshift (deceleration) direction to enable a shift operation at the time of failure or the like is applied, the direction in which the gear ratio increases or decreases. Also results in a different shift response, resulting in deviation from the target shift control characteristic.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a control device for a continuously variable automatic transmission in which a desired shift response is reliably exhibited.

[0008]

According to a first aspect of the present invention, as shown in FIG. 15, a pair of variable pulleys on a driving side and a driven side, in which a width of a contact pulley with a V-belt is variably controlled based on hydraulic pressure, is provided. A continuously variable transmission 1, a shift control valve 2 for controlling the oil pressure based on a speed ratio command value, and a detecting means 3 for detecting an operating state of the vehicle and an actual speed ratio of the continuously variable transmission. A target gear ratio setting unit 4 for setting a target gear ratio from the detected operating state; a dynamic characteristic estimating unit 5 for setting a constant relating to a dynamic characteristic of the continuously variable transmission for each gear ratio; Control means 7 having a shift command section 6 for outputting a shift ratio command value to control the shift ratio of the continuously variable transmission 1 based on the speed ratio and a constant for each speed ratio is provided.

[0009] The second invention is the above-mentioned first invention, wherein:
The dynamic characteristic estimating unit 5 is provided with means for determining a gear direction based on a change in the detected gear ratio, and sets a constant for each gear ratio in accordance with the gear direction.

In a third aspect, in the first aspect,
The dynamic characteristic estimating unit 5 is provided with means for determining a gear shift direction based on the pressure increasing / decreasing state of the gear shift control valve, and a constant for each gear ratio is set according to the gear shift direction.

In a fourth aspect, the control means of the first and second aspects includes a conversion means for converting the speed ratio command value so that the speed ratio command value and the actual speed ratio have a proportional relationship. It was taken.

[0012] The fifth invention, the conversion means of the fourth invention, the relationship between the moving amount D _s of the driving pulley interval obtained from the following equation (a) ~ (c) and the gear ratio ip Based on this, the conversion amount of the speed ratio command value is determined so that the proportional relationship between the speed ratio command value and the speed ratio ip is established.

[0013] _{r i = {D s / 2tan} (β)} + r io ... (a) r o = [2r i -πD c + {(2r i -πD c) 2 -4 (r i 2 + D c r _{i + D c (2D c -L} B))} 1/2] / 2 ... (b) ip = r o / r i ... (c) However, r _i: radius r _io belt contact part of drive pulley : Minimum radius of drive side pulley r _o : Radius of belt contact part of driven side pulley D _c : Center distance between drive side pulley and driven side pulley L _B : Belt circumference β: Pulley sheave angle.

According to a sixth aspect based on the third aspect,
The transmission control valve is connected to a driving unit that drives the transmission control valve based on a transmission ratio command value via a link that compensates for a deviation between the displacement of the driving unit and the driving pulley displacement of the continuously variable transmission. On the other hand, the pressure increase / decrease state of the shift control valve is calculated based on a deviation between the shift control valve displacement estimated from the command value to the driving means and the driving pulley displacement estimated from the actual gear ratio. It was taken.

According to a seventh aspect, in the third aspect,
A dynamic characteristic compensation output calculation unit for calculating a dynamic characteristic compensation output of the continuously variable transmission based on the target speed ratio, the actual speed ratio, and a constant relating to dynamic characteristics for each speed ratio; A disturbance compensation constant calculator for calculating a cut-off frequency of a low-pass filter of a disturbance compensation output unit described later based on a constant relating to the dynamic characteristic of the motor; and a low-pass filter for setting a cut-off frequency based on the cut-off frequency. A first disturbance compensation output calculator for inputting a command value to calculate a first disturbance compensation output; and a low-pass filter having characteristics similar to those of the low-pass filter of the first disturbance compensation output calculator. A second disturbance compensation output operation unit configured to constitute a filter obtained by multiplying an inverse system of a low-pass filter using a constant related to and calculate a second disturbance compensation output using the actual gear ratio as an input; A disturbance compensation output section for calculating the disturbance compensation output by subtracting the first disturbance compensation output from the second disturbance compensation output, and the shift command section subtracts the disturbance compensation output from the dynamic characteristic compensation output to the drive means. And a first displacement estimator for estimating a first driving means displacement from a command value to the driving means, and calculating a correction amount of the driving means displacement from the disturbance compensation output. A displacement correction amount calculating unit, a second displacement estimating unit for estimating a second drive unit displacement from the first drive unit displacement and the displacement correction amount, a drive-side pulley displacement and the second drive unit displacement And a pressure increasing / decreasing state estimating section for estimating the pressure increasing / decreasing state of the shift control valve based on the deviation from the above.

According to an eighth invention, in the seventh invention,
The displacement correction amount calculation unit includes a disturbance compensation output steady value calculation unit that calculates a steady value of the disturbance compensation output from the disturbance compensation output using a low-pass filter, and calculates a displacement correction amount of the driving unit from the disturbance compensation output steady value. It is configured to be operated.

[0017]

According to the first aspect of the invention, a constant is set according to a dynamic characteristic (gain or time constant) determined for each speed ratio of the continuously variable transmission, and a speed ratio command value is calculated using the control constant. Therefore, it is possible to control the speed ratio of the continuously variable automatic transmission with a speed change response as previously targeted when shifting from an arbitrary speed ratio.

In the second invention, since the constant of the first invention is determined for each speed ratio in accordance with the speed change direction, even when the dynamic characteristics of the continuously variable transmission differ depending on the speed change direction, this is not necessary. Appropriate shift control can be performed accordingly.

In the third aspect, the shift direction is determined based on the increase or decrease state of the shift control valve, so that more accurate shift control can be performed.

According to the fourth aspect of the invention, the transmission ratio command value to be applied to the transmission control valve is converted so that the transmission ratio command value and the actual transmission ratio are in a proportional relationship. Appropriate shift control is performed even if the structure has different flow characteristics or if the transmission has a characteristic in which the gear ratio changes nonlinearly with the operation of the control system. Can be.

In the fifth invention, when the variable pulley of the continuously variable transmission is hydraulically controlled via the transmission control valve in the third invention, the change in the gear ratio with respect to the movement amount of the variable pulley is compensated in a proportional relationship. Therefore, more appropriate control can be performed.

According to a sixth aspect of the present invention, in the configuration wherein the shift of the shift control valve is mechanically connected to each other via a link such that the shift of the shift control valve is corrected by a deviation between the displacement of the drive means and the displacement of the drive pulley. The increase / decrease state of the shift control valve is calculated based on the deviation between the shift control valve displacement estimated from the command value to the drive means and the drive-side pulley displacement estimated from the actual gear ratio. The pressure state can be accurately detected, and the constant relating to the dynamic characteristic can be set appropriately.

Further, according to the seventh and eighth aspects of the present invention, the influence of errors and disturbances on driving means such as a step motor for driving the shift control valve is eliminated, so that deterioration of control accuracy caused by such disturbances is avoided. As a result, a more reliable and accurate shift control can be performed.

[0024]

Embodiments of the present invention will be described below.

FIG. 1 shows a longitudinal sectional structure of a continuously variable automatic transmission to which the present invention can be applied. To explain this, a torque converter 1 as a hydraulic power transmission is provided on an engine output shaft 10.
2 are connected. In some cases, a fluid coupling, an electromagnetic clutch, or the like is used instead of the torque converter 12 as the hydraulic power transmission device.

The torque converter 12 is provided with a lock-up clutch 11, and reciprocally controls the oil pressure in the converter chamber 12c and the lock-up oil chamber 12d, so that the input side pump impeller 12a and the output side turbine runner 12b are connected to each other. Can be mechanically connected or disconnected.

The output side of the torque converter 12 is the rotary shaft 1
3 and the rotating shaft 13 is connected to a forward / reverse switching mechanism 15. The forward / reverse switching mechanism 15 includes the planetary gear mechanism 1
9, a forward clutch 40, a reverse brake 50 and the like. The output side of the planetary gear mechanism 19 is the rotating shaft 13
The drive shaft 14 is coaxially fitted to the outside of the drive shaft 14. The drive shaft 14 has a drive-side pulley 16 of a continuously variable transmission 17.
Is provided.

The continuously variable transmission 17 includes the driving pulley 16
, A driven pulley 26, and a V-belt 24 that transmits the rotational force of the driving pulley 16 to the driven pulley 26.

The drive-side pulley 16 is arranged opposite to the fixed conical plate 18 to rotate integrally with the drive shaft 14, and is arranged opposite to the fixed-cone plate 18 to form a V-shaped pulley groove and acts on the drive-side pulley cylinder chamber 20. The movable conical plate 22 is movable in the axial direction of the drive shaft 14 by hydraulic pressure. In this case, the driving pulley cylinder chamber 20 is composed of two chambers, a chamber 20a and a chamber 20b, and has a larger pressure receiving area than a driven pulley cylinder chamber 32 described later.

The driven pulley 26 is provided on a driven shaft 28. The driven pulley 26 is driven by a fixed conical plate 30 that rotates integrally with the driven shaft 28, and is disposed to face the fixed conical plate 30 to form a V-shaped pulley groove and hydraulic pressure acting on the driven pulley cylinder chamber 32. The movable conical plate 34 is movable in the axial direction of the shaft 28.

A drive gear 46 is fixed to the driven shaft 28, and the drive gear 46 meshes with an idler gear 48 on an idler shaft 52. A pinion gear 54 provided on the idler shaft 52 is engaged with the final gear 44. The final gear 44 drives a propeller shaft or a drive shaft to wheels (not shown) via a differential device 56.

The torque input from the engine output shaft 10 to the continuously variable automatic transmission as described above is applied to the torque converter 1
When the forward clutch 40 is engaged and the reverse brake 50 is released, the planetary gear mechanism 19 that is integrally rotated is transmitted to the forward / reverse switching mechanism 15 via the rotation shaft 2 and the rotary shaft 13. The rotational force of the rotary shaft 13 is transmitted to the drive shaft 14 of the continuously variable transmission 17 while maintaining the same rotational direction, while the planetary gear is engaged when the forward clutch 40 is released and the reverse brake 50 is engaged. Due to the action of the gear mechanism 19, the rotational force of the rotary shaft 13 is transmitted to the drive shaft 14 in a state where the rotational direction is reversed.

The rotational force of the drive shaft 14 is
The power is transmitted to the differential 56 through the V-belt 24, the driven pulley 26, the driven shaft 28, the drive gear 46, the idler gear 48, the idler shaft 52, the pinion gear 54, and the final gear 44. When both the forward clutch 40 and the reverse brake 50 are released, the power transmission mechanism is in a neutral state.

At the time of power transmission as described above, the movable conical plate 22 of the driving pulley 16 and the movable conical plate 34 of the driven pulley 26 are moved in the axial direction to change the contact position radius with the V-belt 24. Thus, the rotation ratio between the driving pulley 16 and the driven pulley 26, that is, the gear ratio (reduction ratio) can be changed. For example, the driving pulley 16
Of the V-shaped pulley groove of the driven pulley 2
If the width of the V-shaped pulley groove 6 is reduced, the driving pulley 1
Since the contact position radius of the V-belt 24 on the 6 side becomes smaller and the contact position radius of the V-belt of the V-belt 24 on the driven pulley 26 side becomes larger, a large gear ratio can be obtained. If the movable conical plates 22 and 34 are moved in the opposite directions, the gear ratio becomes smaller, contrary to the above.

The control for changing the widths of the V-shaped pulley grooves of the driving pulley 16 and the driven pulley 26 is performed by a driving pulley cylinder chamber 20 via a control system described below.
(20a, 20b) or driven pulley cylinder chamber 32
This is performed by controlling the hydraulic pressure.

FIG. 2 schematically shows a control system having a function of performing the basic gear ratio control of the above-described continuously variable automatic transmission, including the function of the control means of the present invention. In FIG. 2, the same reference numerals are given to the mechanical parts corresponding to those in FIG.

Hereinafter, this control system will be described.
In the figure, reference numeral 101 denotes an electronic control unit comprising a microcomputer or the like, and 102 denotes a hydraulic control unit comprising various hydraulic control valves or the like. In this control system, the control means of the continuously variable automatic transmission mainly includes these electronic control units 101 And a hydraulic control unit 102.

The electronic control unit 101 includes a central processing unit 101A that performs control arithmetic processing, an input unit 101B that converts various operating state signals from the engine and the vehicle into a processable format and supplies the central processing unit 101A with a processable format. Central processing unit 1
The output unit 101C outputs various signals for hydraulic control and the like based on a control signal from the control unit 01A.

The input unit 101B includes a water temperature signal S1, a throttle opening signal S2, an engine rotation signal S3, and an ABS used by a control module 103 for electronically controlling the fuel injection amount and ignition timing of the engine 100.
(Anti-lock brake system) An ABS operation signal S4 from the control device 104, a braking signal S5 generated when the vehicle's braking device is operated, a selector position signal S6 generated from the inhibitor switch as a signal indicating the operation position of the selector lever 105, a driving side. Pulley 16 rotation speed signal S
7 (turbine rotation speed signal), the rotation speed signal S8 (vehicle speed signal) of the driven pulley 26, and the like, and supply these signals to the central processing unit 101A as necessary.

The central processing unit 101A includes a transmission control unit 10
6. Line pressure control unit 107, lock-up control unit 108
A control signal is calculated using necessary predetermined signals from the various signals, and a step motor drive circuit 109, a line pressure solenoid drive circuit 110, and a lock-up solenoid drive circuit 11 constituting the output unit 101C are formed.
By driving the transmission 1, the transmission ratio, the line pressure, and the lock-up clutch 11 of the continuously variable transmission 17 are controlled.

More specifically, the shift control unit 106 controls the step motor drive circuit 109 so that the shift is performed according to a predetermined pattern according to the engine load represented by the throttle opening, the rotational speed, the vehicle speed, and the like. Output a signal. Based on this control signal, the step motor drive circuit 109 drives the step motor 113 connected to the shift control valve 112 of the hydraulic control unit 102.

That is, the step motor 113 drives the shift control valve 112 so as to have a speed ratio corresponding to a signal from the step motor drive circuit 109, and the drive side pulley cylinder chamber 20 and the driven pulley cylinder chamber 32 (see FIG. 1). )
The line pressure supplied to is increased or decreased reciprocally. The displacement of the driving pulley 16, that is, the gear ratio, is fed back to the gear change control valve 112 via a link 114. The hydraulic pressure distribution is made constant and stabilized at the target gear ratio.

On the other hand, when the speed ratio of the continuously variable transmission 17 is controlled in this manner, if the line pressure supplied to each of the pulleys 16 and 26 is too small, the pulleys 16 and 18 and the V belt 24 Slip occurs due to lack of friction between them,
Conversely, if the line pressure is excessive, the frictional force becomes unnecessarily large, and in any case, the fuel efficiency and power performance of the vehicle are adversely affected. Therefore, the line pressure control unit 107 controls the line pressure via the line pressure solenoid drive circuit 110 so that appropriate power transmission with no excess or deficiency can be performed according to the operation state.

That is, the line pressure solenoid drive circuit 1
10 is a line pressure solenoid 115 of the hydraulic control unit 102
Is controlled in accordance with a control signal from the drive circuit 110, and in response to this, the line pressure solenoid 115 changes the hydraulic pressure from a hydraulic pump (not shown) to a modifier (pressure control valve) 116 and a regulator (constant pressure valve). The pressure is adjusted to an appropriate target line pressure via 117 and supplied to the shift control valve 112 or the pulleys 16 and 26.

The lock-up control unit 108 controls the hydraulic pressure so that the lock-up clutch 11 is connected when the vehicle speed becomes equal to or higher than a predetermined value and released when the vehicle speed becomes equal to or lower than the predetermined value. .

That is, the lock-up control unit 108
The lock-up solenoid 11 of the hydraulic control unit 102 via the lock-up solenoid drive circuit 111 according to the vehicle speed
8 to control switching of the lock-up control valve 119. In this case, the lock-up control valve 119
A system for supplying hydraulic pressure from the hydraulic pump to the converter chamber 12c of the torque converter 12 as an apply pressure for connecting the lock-up clutch 11, and a system for supplying the hydraulic pressure from the hydraulic pump to the lock-up oil chamber 12d as a release pressure for releasing the same. And so on. That is, when the lock-up clutch 11 is connected, the apply pressure is supplied to the converter chamber 12c and the lock-up oil chamber 12d is released, so that the lock-up clutch 11
Is released, the release pressure is supplied to the lock-up oil chamber 12d and the converter chamber 12c is opened.

The above is an example of a continuously variable automatic transmission to which the present invention can be applied. In the present invention, such a continuously variable automatic transmission has a dynamic characteristic unique to the continuously variable transmission. The purpose of the present invention is to set a gear ratio command value so as to obtain an intended gear response.

FIG. 3 is a functional block diagram showing an example of the structure of the shift control section 106 for performing such control as the first embodiment, which is mainly based on the first, second, and second embodiments. 4. This corresponds to the fifth invention. In the figure, reference numeral 410 denotes a target speed ratio calculation unit for calculating a target speed ratio _ipT corresponding to the operation state based on the various operation state signals described above such as the throttle opening signal S2 and the engine rotation signal S3. A shift command section 430 that outputs a step motor drive signal Sθ as a final command value based on a comparison between the speed ratio i _pT and the actual speed ratio i _pR.
Is the actual speed ratio i of the continuously variable transmission from the rotation speed signal S7 of the driving pulley 16 and the rotation speed signal S8 of the driven pulley 26.
_This is an actual speed ratio calculation unit that calculates _pR . Shift command section 420
Is obtained by feeding back the actual speed ratio i _pR to the target speed ratio i _pT such that the speed ratio changes with a predetermined characteristic to the target speed ratio i _pT .
In addition to the speed change ratio command value calculating section 440 for calculating a i _p, it is provided with a step motor angular position adjusting unit 450 outputs a drive signal Sθ converts the result of the calculation in the angular position of the step motor 113.

The control contents of the shift control unit 106 will be described with reference to a flowchart shown in FIG. 4. In this control, a waiting time is set for performing a shift control at every predetermined control cycle, and the elapse is waited for. First, the actual speed ratio i _pR is calculated based on the input / output shaft speed signals S7 and S8 of the continuously variable transmission, and the speed ratio is increased or reduced based on a comparison between this _ipR and the previous calculated value. A shift direction value Sd is set, which indicates which direction of decrease is changing. (Steps 101 to 103) Next, the target gear ratio is calculated based on the operation state signal.
After calculating the i _pT, the dynamic characteristic of each speed ratio i _p and the transmission direction Sd which has been determined by experiment or the like for each model of the CVT
And G _P (s), shift response G _T (s) because of each gear ratio control constants C ₁ designer desires (i _p), calculates the C ₂ (i _p), the gear ratio on the basis of these calculating a command value Si _p. (Steps 104-1
06) Here, the G _P (s), represented by _{G T (s), C 1} (i p), C 2 (i p), Si p the following formula, respectively (1) to (5) .

G _P (s) = K _p (i _p ) · exp (−Ls) / {T _P (i _p s) +1} (1) G _T (s) = exp (−Ls) / ( T _T s + 1)… (2) C ₁ (i _p ) = T _P (i _p ) / {T _P (i _p )-T _T }… (3) C ₂ (i _p ) = {T _T / T _P (i _p )}-1… (4) S i _p = C ₂ (i _p ) × {C ₁ (i _p ) × i _pT (t)-i _pR (t)}… (5) where K _P (i _p): gain T _P of the continuously variable transmission (i _p): gear ratio and time constants of the continuously variable transmission that is determined for each transmission direction (see FIG. 5) T _T: time constant corresponding to the design goals L : Dead time s: Differential operator t: Time (current time of the control calculation cycle) _ipT (t): Target gear ratio at time t _ipR (t): Actual gear ratio at time t.

The speed change ratio command value computed this way Si _p
Reflects the speed ratio of the continuously variable transmission and the dynamic characteristics of each speed direction, that is, represents a speed change response as originally intended for an arbitrary speed ratio and speed direction. However, in general, since the angular position of the step motor 113 and the speed ratio of the continuously variable transmission are not directly proportional, in this case, the step motor angular position, that is, the drive signal Sθ is set so that the gear ratio command value is set so that the proportional relationship is established. It converted to a value corresponding to the Si _p so that output. (Steps 107 to 109) The following equations (6) to (8) show relational equations for this conversion.
In this case, based on the relationship between speed ratio ip and the moving amount D _s of the drive side pulley interval corresponding to the step motor angular speed ratio command value and the like proportional relationship between the speed ratio ip is established gear ratio command value Is determined.

[0052] _{r i = {D s / 2tan} (β)} + r io ... (6) r o = [2r i -πD c + {(2r i -πD c) 2 -4 (r i 2 + D c r _i + D _c (2D _c −L _B ))} ^1/2 ] / 2… (7) ip = r _o / r _i … (8) where r _{i is} the radius r of the belt contact portion of the driving pulley. _io : Minimum radius of the driving pulley r _o : Radius of the belt contacting part of the driven pulley D _c : Distance between the shafts between the driving pulley and the driven pulley L _B : Belt circumference β: Sheave angle of the pulley .

Since the specifications of the continuously variable transmission are known, the conversion amount is not calculated based on the conversion formula every time control is performed, but the result calculated in advance is shown in FIG. It may be configured to read out the data mapped as described above or the data obtained by mapping the conversion amount obtained based on the actual measurement result. FIG. 7 is a block diagram showing a control concept when the conversion amount is determined by reading the map. Further, the conversion amount is set for the purpose of defining the relationship between the pulley position and the gear ratio of the continuously variable transmission having the variable pulley. If the flow rate characteristics differ depending on the characteristics, it is preferable to perform the same conversion in order to compensate for the non-linear relationship that occurs between the shift control valve position and the speed ratio due to the characteristic change.

FIG. 8 shows a simulation in which a control system is designed with the target shift response in the above embodiment as G _T (s) = exp (-0.09 s) / (0.3 s + 1). The results show that it is possible to obtain the target shift response as shown.

[0055] Incidentally, a technique for calculating the speed ratio command value Si _p is not limited to those described above, for example, the following formula
It may be determined by an arithmetic expression such as (9).
FIG. 9 is a block diagram of a control concept corresponding to the arithmetic expression.

[0056] _{Si p (t) = C 2} (i p) × [C 1 (i p) × {i pT (t) -i pR (t)} - G cs (s) × Si p (t)] … (9) where G _cs (s) = {1 / T _P (i _p ) s + 1}-{exp (-Ls) / T _P (i _p ) s + 1}
, And Si _p (t) on the right side is the previous value of the command value.

A desired shift response can be realized by a feedforward compensator represented by the following equation (10). FIG. 10 is a block diagram showing the control concept in this case.

[0058] _{Si p (t) = {T} P (i p) s + 1} i pT Note _{(t) / (T T s} + 1) ... (10), also in the PID control, etc., the respective control constants It is possible to obtain a desired shift response by calculating in the same manner as described above.

Next, a second embodiment of the present invention will be described. This mainly has contents corresponding to the third, sixth to eighth aspects of the invention. That is, when determining a control constant representing the dynamic characteristics of the continuously variable transmission for each shift direction, the control of the shift control valve is performed. It is characterized in that the shift state is determined based on the pressure increasing / decreasing state.

In the first embodiment, it is desirable to provide hysteresis in order to prevent hunting of the speed ratio due to a minute change in the target speed ratio. In this case, however, it is necessary to gradually increase or decrease the speed ratio. Response delay may occur. On the other hand, according to the second embodiment, since the dynamic characteristic is estimated from the pressure increasing / decreasing state of the shift control valve, it is possible to more accurately determine the shift state and realize an accurate shift response. is there.

FIG. 11 is a block diagram showing the function of the speed change control unit 106 according to this embodiment, and basically comprises a target speed ratio calculation unit 410, a speed change command unit 420, and an actual speed ratio calculation unit 430. In this respect, it is the same as that shown in FIG. However, the shift command section 420 includes a dynamic characteristic compensation output calculation section 440, a disturbance compensation output section (consisting of a first disturbance compensation output calculation section 451 and a second disturbance compensation output calculation section 452), and a shift control valve opening. Direction calculation unit 460, pressure increase / decrease state determination unit 470, control target characteristic calculation unit 480, dynamic characteristic compensation constant calculation unit 490, disturbance compensation constant calculation unit 50
0, a gear ratio command value converter 510 and a step motor angular position adjuster 520. The details of the control operation by these are as follows.

As a reference model on which the arithmetic processing by the control system is based, first, the dynamic characteristic G _P (s) of the continuously variable transmission is expressed by the following equation (11).

G _P (s) = K _p (i _p ) · exp (−Ls) / {T _P (i _p , P _d ) s + 1} (11) The difference from equation (1) is a constant T _P when the variable transmission (i _{p, P d),} is set increasing vacuum of not only the speed ratio change control valve as a constant which changes every (shift command spool displacement of the shift control valve 112) It is a point.

The actual speed ratio calculating section 430 calculates the actual speed ratio _ipR from the vehicle speed signal and the turbine speed signal. Here in the above time constant _{T P (i p, P d} ) In determining the shift control valve opening direction calculating section 460 and decreasing pressure state determination portion 470 determines increasing vacuum of the shift control valve. Since the pressure increase / decrease state is determined by the opening direction (pressure increase side, pressure decrease side) of the shift control valve, it can be determined from the shift control valve displacement. The shift control valve displacement is calculated from the shift command spool displacement of the shift control valve and the drive-side pulley displacement based on the following equation. That is, first, the drive-side pulley displacement X _pp is calculated from the actual speed ratio i _pR by the formula (1)
It is determined from a map created using 2) and (13) or a map created using experimental data (see FIG. 12). The meanings of the symbols in the formula are the same as those in formulas (6) and (7).

[0065] _{X pp = (r i - r} io) 2tan (β) ... (12) r i = [πD c (1 + i pR) + {πD c (1 + i pR) 2 -8 (i pR - 1) the ^{_{2 D c (2D c -L B}} )} 1/2] / 2 (i pR -1) 2 ... (13), a shift command spool displacement X _SC is the corner of the step motor is driving means When the position command value Sθ matches the angular position θ, it can be calculated based on the following equation (14).

[0066] _{X SC = Sθ · D S ...} (14) However, D _S: a shifting command spool displacement amount per one step of the stepper motor.

The stepping motor is provided between the angular position command value Sθ and the actual angular position θ when the stepping motor is controlled by feedforward control due to variations in assembly or mechanical play. There is a possibility that a deviation occurs (this deviation is called “step-out”). Therefore, it is more desirable to calculate the shift command spool displacement in consideration of the displacement caused by the step-out. Therefore, the shift command spool displacement due to step-out is estimated from the disturbance compensation output described later, and the value obtained from the following equation (15) is corrected to calculate the shift command spool displacement. Since the shift command spool displacement due to step-out can be considered as a disturbance that occurs steadily, this displacement X _err is the disturbance compensation output Si.
_From the disturbance output steady value _SipDT calculated by applying a low-pass filter, for example, as shown in equation (16) to _pD , in the same manner as in the calculation of the drive-side pulley displacement described above, for example, FIG.
2 can be obtained from the same map.

[0068] _{Si pDT = Si pD / (T} L s + 1) ... (15) X err = f (Si pDT) ... (16) However, f (): a function for converting the gear ratio shift command spool displacement is there.

The shift command spool displacement X _scc taking into account the _loss of _synchronism is calculated based on the following equation (17).

X _scc = X _sc + X _err (17) The shift control valve displacement X _st and the pressure increasing / decreasing state are obtained from the drive side pulley displacement X _pp and the shift command spool displacement X _scc by the following equation.
It can be calculated based on (18).

X _st = (X _scc -X _pp ) / i _L (18) where i _L : lever ratio of link 114 (see FIG. 2).

Here, if X _st ≧ 0, it can be considered that the pressure is reduced and if X _st <0, it is considered that the pressure is increased.

Then, from the pressure increase / decrease state and the actual gear ratio,
Determining the time constant T _p with constant map when you created based on the parameters in advance identification experiment (see Fig. 5).

In the dynamic characteristic compensation output calculation section 440,
When the dynamic characteristic G _T (s) desired by the designer is given by the following equation (19), the dynamic characteristic compensator output S is calculated based on the following equations (20) to (23).
Calculate i _pA .

G _T (s) = exp (−Le) / (T _T s +1) (19) where T _T is a time constant of a response desired by the designer.

[0076] _{Si pAF (t) = {T} FB (i p, P d) s + 1} S ipT (t) / (T T s + 1) ... (20) However, Si _pAF (t): Dynamic Characteristics Compensator feed forward section output T _FB : Time constant of response targeted by the dynamic characteristic compensator feedback section. _SipT : Target gear ratio.

[0077] _{C 1 = T p / T FB} ... (21) C 2 = T p / T FB - 1 ... (22) Si pA = C 1 S ipAF - C 2 i pR ... (23) disturbance compensation output portion 450 Is based on the dynamic characteristic of the continuously variable transmission described by the equation (11) as a reference model, and removes this reference model from being disturbed by disturbances such as mass production variation (parameter fluctuation) and step-out of the step motor. Designed to.
In this case, the disturbance compensation output section 450 outputs the speed ratio command value Si
_From the following equation (24), the disturbance compensation output Si _{pD is obtained} from _pc and the actual speed ratio i _pR.
Is calculated.

[0078] _{Si pD = {T H (i} p, P d) s + 1} i pR (t) / {T p (i p, P d) s + 1} - exp (-Ls) Si pc (t ) / {T _H (i _p , P _d ) s + 1}… (24) where T _H is the cutoff frequency of the low-pass filter of the disturbance compensation output calculation unit, and the dynamic characteristics of the continuously variable transmission and the control system (For example, gain margin of 12 dB or more, phase margin of 45
Degree or more) is satisfied.

The dynamic characteristic compensation output Si _pA and the disturbance compensation output Si _pD
, The speed ratio command value Si _pc is calculated from the following equation (25).

[0080] Si _pc = Si _pA - by using a Si _pD ... (25) speed change ratio command value Si _pc obtained in this manner, less susceptible to parameter variations and disturbances,
The shift response desired by the designer can be obtained with high accuracy. However, since the angular position of the step motor with respect to the speed ratio is not directly proportional, the speed ratio command value conversion unit 510 uses the relationship of the above-described equations (6) and (7) or a map as shown in FIG. , it converted to a step motor angular position command value Sθ corresponding to the gear ratio command value Si _pc is performed.

FIGS. 13 and 14 show the effect of each of the above embodiments, in which the gear ratio rapidly changes in the downshift direction (the pressure reduction direction of the shift control valve) by kickdown acceleration, and thereafter the acceleration is terminated. This simulates a shift response in an operating state in which the speed ratio gradually changes in the upshift direction (also in the pressure increasing direction). FIG. 13 shows the shift response according to the first embodiment, and generally shows a target shift response. However, the shift response shifts from downshift to upshift and the speed ratio starts to increase gently. There is a slight delay in the subsequent response. On the other hand, FIG. 14 shows a shift response according to the second embodiment, and it can be seen that the shift ratio faithfully changes with respect to the target even after the shift to the upshift.

[0082]

As described above, according to the first aspect, the gear ratio command value is calculated using the constant corresponding to the dynamic characteristic determined for each gear ratio of the continuously variable transmission. The response characteristics at the time are always controlled as desired, so that the control of the automatic transmission can be performed more appropriately and accurately.

In the second invention, the constant relating to the dynamic characteristics of the continuously variable transmission according to the first invention is determined for each speed ratio in accordance with the speed change direction. Even in the case where the dynamic characteristics of the continuously variable transmission differ depending on the shift direction, appropriate shift control can be performed correspondingly.

According to the third aspect of the present invention, the constant relating to the dynamic characteristics of the continuously variable transmission is determined in accordance with the increase / decrease state of the shift control valve. Control can be performed.

According to the fourth or fifth aspect, the speed ratio command value is converted so that the speed ratio command value and the actual speed ratio have a proportional relationship. The calculation can be performed assuming that the speed ratio changes in proportion to the value. Therefore, the speed ratio of the continuously variable transmission can be appropriately controlled while generalizing the configuration of the control system and simplifying the configuration.

According to the sixth aspect, the shift control valves are mechanically connected to each other via the link such that the shift of the shift control valve is corrected by the deviation between the shift of the drive means and the shift of the drive pulley. The stepless speed change is performed by calculating the pressure increase / decrease state of the shift control valve based on the deviation between the shift control valve displacement estimated from the command value to the drive means and the drive pulley displacement estimated from the actual gear ratio. The shift control valve, which indicates the shift direction of the machine, determines whether the pressure is increasing or decreasing. Therefore, even in an operating state in which the gear ratio changes gradually, this is reliably reflected in the shift control to achieve high-accuracy shift response. Can be demonstrated.

According to the seventh or eighth aspect of the present invention, by applying disturbance compensation to a constant relating to the dynamic characteristics of the continuously variable transmission, a driving means such as a step motor for driving a shift control valve is generated. Since the effects of errors and disturbances are eliminated, deterioration of control accuracy due to such disturbances is also avoided, and shift response characteristics with higher reliability and accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a continuously variable transmission according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a control system.

FIG. 3 is a block diagram illustrating a configuration of a shift control unit in FIG. 2;

FIG. 4 is a flowchart showing the operation content of the first embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a speed ratio and a time constant of the continuously variable transmission for each speed change direction.

FIG. 6 is a characteristic diagram showing a relationship between a step motor angular position and a gear ratio.

FIG. 7 is a block diagram conceptually showing a calculation method of a gear ratio command value.

FIG. 8 is a characteristic diagram showing a simulation result of a shift response according to the first embodiment.

FIG. 9 is a block diagram conceptually showing another calculation method of the speed ratio command value.

FIG. 10 is a block diagram conceptually showing still another calculation method of a gear ratio command value.

FIG. 11 is a block diagram showing a configuration of a shift control unit according to a second embodiment of the present invention.

FIG. 12 is a characteristic diagram showing a relationship between a drive-side pulley displacement and an actual gear ratio.

FIG. 13 is a characteristic diagram showing a simulation result of a shift response according to the first embodiment.

FIG. 14 is a characteristic diagram showing a simulation result of a shift response according to the second embodiment.

FIG. 15 is a block diagram showing a configuration of the present invention.

[Explanation of symbols]

 Reference Signs List 1 continuously variable transmission 2 shift control valve 3 operating state detecting means 4 target gear ratio setting section 5 dynamic characteristic estimating section 6 shift commanding section 7 control means 10 engine output shaft 12 torque converter 13 rotating shaft 14 drive shaft 16 drive pulley 24 V-belt 26 driven pulley 28 driven shaft 101 electronic control unit 101A central processing unit 101B input unit 101C output unit 102 hydraulic control unit 105 selector lever 106 shift control unit 107 line pressure control unit 108 lockup control unit 109 step motor drive circuit 110 Line pressure solenoid drive circuit 111 Lock-up solenoid drive circuit 112 Shift control valve 113 Step motor 114 Link

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F16H 63:06 (56) References JP-A-8-296708 (JP, A) JP-A-59-219554 (JP, A) ( 58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 61/00-61/24

Claims (8)

(57) [Claims] 1. A continuously variable transmission having a pair of variable pulleys on a driving side and a driven side in which a width of a contact pulley with a V-belt is variably controlled based on a hydraulic pressure, and controlling the hydraulic pressure based on a gear ratio command value. A speed change control valve, and a detection means for detecting an operating state of the vehicle and an actual gear ratio of the continuously variable transmission, a target gear ratio setting unit for setting a target gear ratio from the detected operating state, and a gear ratio A dynamic characteristic estimating unit that sets a constant relating to a dynamic characteristic of the continuously variable transmission for each time, and outputs a speed ratio command value based on the actual speed ratio, the target speed ratio, and the constant for each speed ratio to perform continuously variable transmission. A control device for a continuously variable automatic transmission, further comprising control means having a shift command unit for controlling a speed ratio of the transmission. 2. The dynamic characteristic estimating unit includes means for determining a gear shift direction based on a change in a detected gear ratio, and sets a constant for each gear ratio in accordance with the gear direction. 3. The control device for a continuously variable automatic transmission according to claim 1. 3. The dynamic characteristic estimating unit includes means for determining a shift direction based on a pressure increase / decrease state of a shift control valve, and sets a constant for each gear ratio in accordance with the shift direction. Item 2. A control device for a continuously variable automatic transmission according to item 1. 4. The control unit according to claim 1, wherein the control unit includes a conversion unit that converts the speed ratio command value so that the speed ratio command value and the actual speed ratio have a proportional relationship. 3. The control device for a continuously variable automatic transmission according to claim 1. 5. A converting means, based on the relationship of the following equation (a) ~ a moving amount D _s of the driving pulley interval obtained from (c) and the gear ratio ip, the gear ratio command value and the speed ratio ip 5. The control device for a continuously variable automatic transmission according to claim 4, wherein the conversion amount of the speed ratio command value is determined so that a proportional relationship is established. _{r i = {D s / 2tan} (β)} + r io ... (a) r o = [2r i -πD c + {(2r i -πD c) 2 -4 (r i 2 + D c r i + D _c (2D _c -L _B ))} ^1/2 ] / 2… (b) ip = r _o / r _i … (c) where r _i : radius of the belt contact portion of the driving pulley r _io : driving side The minimum radius of the pulley r _o : the radius of the belt contact portion of the driven pulley D _c : the center distance between the driving pulley and the driven pulley L _B : the circumference of the belt β: the sheave angle of the pulley. 6. A link for compensating a deviation between a displacement of the driving means and a displacement of a driving pulley of the continuously variable transmission to a driving means for driving the transmission control valve based on a speed ratio command value. The pressure increase / decrease state of the transmission control valve is calculated based on the deviation between the transmission control valve displacement estimated from the command value to the driving means and the driving pulley displacement estimated from the actual gear ratio. The control device for a continuously variable automatic transmission according to claim 3, wherein the control device is configured to perform the following operations. 7. A dynamic characteristic compensation output calculating section for calculating a dynamic characteristic compensation output of the continuously variable transmission based on a target gear ratio, an actual gear ratio, and a constant relating to a dynamic characteristic for each gear ratio, A disturbance compensation constant calculating unit that calculates a cutoff frequency of a low-pass filter of a disturbance compensation output unit described below based on a constant related to a dynamic characteristic of the continuously variable transmission; and a low-pass in which a cutoff frequency is set based on the cutoff frequency. Input the gear ratio command value to the filter and
A first disturbance compensation output computing section for computing the disturbance compensation output of the above, and a low-pass filter using a constant relating to the dynamic characteristic to a low-pass filter having characteristics similar to those of the low-pass filter of the first disturbance compensation output computing section A second disturbance compensation output calculation unit configured to calculate a second disturbance compensation output using the actual gear ratio as an input, and a first disturbance compensation from the second disturbance compensation output A disturbance compensation output unit for calculating a disturbance compensation output by subtracting an output, wherein the shift command unit is configured to subtract a disturbance compensation output from the dynamic characteristic compensation output to calculate a command value to the driving unit, A first displacement estimating unit that estimates a first driving unit displacement from a command value to the driving unit; a displacement correction amount calculating unit that calculates a correction amount of the driving unit displacement from the disturbance compensation output; A second displacement estimating unit for estimating a second driving means displacement from the moving means displacement and the displacement correction amount; and increasing / decreasing a speed change control valve based on a deviation between the driving pulley displacement and the second driving means displacement. The control device for a continuously variable automatic transmission according to claim 3, further comprising: a pressure increasing / decreasing state estimating unit that estimates a state. 8. A displacement compensation amount calculation unit includes a disturbance compensation output steady value calculation unit that calculates a steady value of the disturbance compensation output from the disturbance compensation output using a low-pass filter, and calculates a steady state of the disturbance compensation output from the disturbance compensation output. The control device for a continuously variable automatic transmission according to claim 7, wherein the control device is configured to calculate a displacement correction amount.