JPH06300097A - Method for controlling speed change of continuously variable transmission - Google Patents

Abstract

PURPOSE:To enable the speed change control appropriate for the driving operation and the running conditions of a vehicle by setting a target change speed of engine speed on the basis of the stored data of the former target change speed. CONSTITUTION:Transient correction of the target engine speed NESPR under the ordinary condition is performed by the rate limit control (302) for performing the filter processing (301) to the NESPR and for setting this processed value as the final target engine speed NESPRF per unit time and for limiting the quantity of change of the NESPRF between an upper limit value RATUP and a lower limit value RATLO. At the time of performing this control (302), setting of RATLO (303) and setting of RATUP (303) of NESPRF to be set on the basis of the driving condition and the travelling condition of a vehicle are performed in consideration of the former NESPRF, namely, NESPRN. Speed change is controlled by controlling the speed change ratio so that the real engine speed NE coincides with the NESPRF, to which the transient correction is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for a continuously variable transmission, and more particularly to a shift control method for a continuously variable transmission capable of performing shift control suitable for a driving operation and a running state of a vehicle.

[0002]

2. Description of the Related Art In a vehicle, a transmission is interposed between an internal combustion engine and driving wheels. This transmission changes the driving force of the driving wheels and the traveling speed in accordance with the traveling condition of the vehicle that changes over a wide range, and thus the performance of the internal combustion engine is fully exhibited. In the transmission, for example, a fixed pulley part fixed to the rotary shaft and a movable pulley part mounted on the rotary shaft so as to be able to come into contact with and separate from the fixed pulley part are formed between both pulley part of the pulley. There is a continuously variable transmission that changes the belt ratio (gear ratio) by increasing and decreasing the groove width of a belt wound around a pulley by hydraulically increasing and decreasing the groove width to transmit power.

Further, some continuously variable transmissions have a hydraulic clutch for connecting and disconnecting power by hydraulic pressure. This hydraulic clutch is controlled in various control modes based on signals such as engine speed and carburetor throttle valve opening.

As the continuously variable transmission, for example, there is one that obtains a final target engine rotation speed by adding transient correction and performs rate limit control of the actual engine rotation speed so as to match the final target engine rotation speed. In some cases, the rate limit control is performed with a value larger than the normal control value when the throttle opening suddenly increases or when the shift operation is performed.

There are also those disclosed in Japanese Patent Publication No. 4-28947 and Japanese Patent Laid-Open No. 4-165162. Particularly, the one disclosed in Japanese Patent Laid-Open No. 4-165162 is
The target change speed of the engine speed is calculated from the difference between the actual engine speed and the target engine speed in the steady state, and the speed change ratio is controlled as the control value. It is corrected by the target change speed of the rotation speed. For reference, the differences between this publication and the invention of the present application are as follows:
While the target change speed of the engine rotation speed is corrected by the target change speed of the engine rotation speed at that time, in the present invention, the target change speed of the engine rotation speed and the accumulated data of the previous target change speed are stored. The target change speed of the engine speed is set by and. That is, assuming that the target change speed of the engine rotation speed is A and the accumulated data of the previous target change speed is B, the target change speed A of the engine rotation speed of the present invention is given by A = α + ΣB or A = α−ΣB. It is set.

[0006]

In the conventional shift control method for a continuously variable transmission, the limit value is set according to the driving operation and the running state of the vehicle, and the driving operation is performed by the throttle operation and the shift operation. While seeking from the operation,
The running condition of the vehicle is calculated from the vehicle speed. Also, the end of transient control is determined by a timer.

However, when the limit value is set by the above method, the following inconveniences occur. That is, it is difficult to always set the limit value suitable for the driving operation of the driver and the traveling state of the vehicle. , There is a fear that the engine rotation speed will change suddenly and give a strange feeling to the driver. It is difficult to reflect the change state of the engine generated torque in order to change the vehicle speed. It is difficult to control the actual engine speed to the steady-state target engine speed. , When the difference between the actual engine speed and the target engine speed in the steady state is large, an integral value is accumulated, and the steady state target engine speed cannot be controlled, that is, normal PI control is performed. There are times when you can't forget. , The running state of the vehicle is not reflected at the end of transient control. However, the control program of the control means is complicated, and the tuning becomes troublesome, which is practically disadvantageous.

Further, in the shift control by the control means, the actual engine rotation speed (NE) is finally controlled to be the steady state target engine rotation speed (NESPR). Speed (NE)
When the difference (ERR) between the engine speed and the target engine speed in the steady state (NESPR) is large and the limit value of the change amount of the transient correction is small, the target engine speed in the steady state of the actual engine speed (NE) There is an inconvenience that the followability to (NESPR) is poor and it is disadvantageous in practical use.

[0009]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides both pulley portions of a fixed pulley portion piece and a movable pulley portion piece attached to and detachable from the fixed pulley portion piece. The steady-state target obtained by increasing or decreasing the groove width between the pieces by hydraulic pressure to decrease the radius of gyration of the belt wound around the pulleys and obtaining the actual engine speed from the shift schedule map of the throttle opening and the vehicle speed. In a shift control method of a continuously variable transmission for performing shift control so as to match a final target engine rotation speed after a transient correction is added to the engine rotation speed, a steady state target engine is provided at the time of transient correction of the steady state target engine rotation speed. The engine speed is filtered and the amount of change in the final target engine speed per unit time is taken into consideration at least in the previous final target engine speed. Set the limit value, characterized in that the shift control to vary said limit value in accordance with the difference between the actual engine rotational speed and the target engine rotational speed in the steady state.

[0010]

According to the invention as described above, at the time of transient correction of the target engine rotation speed in the steady state, the target engine rotation speed in the steady state is filtered and at least the change amount of the final target engine rotation speed per unit time is at least. Set with a limit value that takes into account the last final target engine speed, set a gear shift control to change the limit value according to the difference between the target engine speed in steady state and the actual engine speed, and control the driving and The gear change control suitable for the running condition is achieved.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 11 show an embodiment of the present invention. In FIG. 2, 2 is a continuously variable transmission, 4 is a belt, 6 is a drive side pulley, 8 is a drive side fixed pulley part,
10 is a movable pulley piece on the driving side, 12 is a driven pulley,
Reference numeral 14 is a driven side fixed pulley section piece, and 16 is a driven side movable pulley section piece. As shown in FIG. 2, the drive-side pulley 6 includes a drive-side fixed pulley portion 8 that is fixed to a rotary shaft 18 that is rotated by a prime mover, and the rotary shaft 18 that is movable and non-rotatable in the axial direction of the rotary shaft 18. And a drive-side movable pulley piece 10 mounted on 18. In addition, the driven pulley 12
Has a configuration similar to that of the drive side pulley 6, and includes a driven side fixed pulley portion piece 14 and a driven side movable pulley portion piece 16.

The drive side movable pulley portion piece 10 and the driven side movable pulley portion piece 16 have first and second housings 20, respectively.
22 are attached to each of the first and second hydraulic chambers 2.
4 and 26 are formed respectively. Second hydraulic chamber 26 on the driven side
Inside, there is a pressing spring 28 for urging the driven side movable pulley section piece 16 to approach the driven side fixed pulley section piece 14.
To provide.

An oil pump 30 is provided at the end of the rotary shaft 18. The oil pump 30 passes oil from the oil pan 32 through an oil filter 34 and forms first and second oil passages 38 and 40 that form a hydraulic circuit 36.
Is supplied to the first and second hydraulic chambers 24 and 26. In the middle of the first oil passage 38, a primary pressure control valve 44, which is a shift control valve that constitutes pressure control means 42 for controlling the primary pressure that is the input shaft sheave pressure, is provided. Further, in the third oil passage 46 communicating with the first oil passage 38 on the oil pump 30 side of the primary pressure control valve 44, the line pressure (generally 5 to 25 〓 / 〓 ² ) is kept at a constant pressure (for example, 3 to 4). Constant pressure control valve 4 controlled to 〓 / 〓 ² )
8 are provided. Furthermore, in the primary pressure control valve 44,
First for primary pressure control via fourth oil passage 50
A three-way solenoid valve 52 is connected in series.

In the middle of the second oil passage 40,
A line pressure control valve 54 having a relief valve function for controlling the line pressure that is the pump pressure is connected in series via a fifth oil passage 56. The line pressure control valve 54 is connected to the line pressure control second three-way solenoid valve 60 via a sixth oil passage 58.

Further, a clutch pressure control valve 62 for controlling the clutch pressure is provided in the fifth oil passage 56 in the middle of the second oil passage 40 on the second hydraulic chamber 26 side of the portion where the line pressure control valve 54 communicates. Is provided by utilizing the other end of the branch. The clutch pressure control valve 62 is provided with a third three-way solenoid valve 68 for clutch pressure control via an eighth oil passage 66.
To communicate.

The primary pressure control valve 44, the first solenoid valve 52 for primary pressure control, the constant pressure control valve 48, the line pressure control valve 54, and the second three-way solenoid valve 6 for line pressure control.
0, the clutch pressure control valve 62, and the clutch pressure control third three-way solenoid valve 68 communicate with each other through a ninth oil passage 70.

The clutch pressure control valve 62 communicates with a hydraulic clutch 74 via a tenth oil passage 72 communicating with a seventh oil passage 64. This tenth oil passage 7
A pressure converter 78 is connected via the eleventh oil passage 76 in the middle of the second step. The pressure converter 78 can directly detect the hydraulic pressure when controlling the clutch pressure in the hold and start modes, and has a function of instructing the detected hydraulic pressure to be the target clutch pressure. At times, the clutch pressure becomes substantially equal to the line pressure, which also contributes to the line pressure control.

The hydraulic clutch 74 includes a piston 80,
It is composed of an annular spring 82, a first pressure plate 84, a friction plate 86, a second pressure plate 88 and the like.

Further, a control means (ECU) 90 is provided which is an electronic control unit for inputting various conditions such as a throttle opening of a carburetor (not shown) of the vehicle and engine rotation and changing the duty ratio to control the shift. 90
By the first three-way solenoid valve 52 for controlling the primary pressure,
The line pressure control second three-way solenoid valve 60 and the clutch pressure control third three-way solenoid valve 68 are controlled to open and close, and the pressure converter 78 is also controlled. Further, the various signals input to the control means 90 and the functions of the input signals will be described in detail as follows: a shift lever position detection signal ... Each range signal such as P, R, N, D, L Required line pressure, belt ratio, clutch control, carburetor throttle opening detection signal ...... Engine torque is detected from the memory input in the program in advance, target belt ratio or target engine speed is determined, carburetor idle position Detection signal …… Compensation of the carburetor throttle opening sensor and improvement of accuracy in control, accelerator pedal signal …… Detects the driver's will based on the accelerator pedal depression state, and determines the control direction during running or starting, braking Signal: Detects whether the brake pedal is depressed or not, and controls the clutch disengagement. Decide on the control method, power mode option signal …… The performance of the vehicle is sports (or economy)
Use as an option for

The control means 90 filters the steady-state target engine rotation speed at the time of transient correction of the steady-state target engine rotation speed, and at least determines the final target engine rotation speed change amount per unit time at the last time. The target engine rotation speed is set with a limit value taken into consideration, and shift control is performed to change the limit value according to the difference between the target engine rotation speed in the steady state and the actual engine rotation speed.

The control means 90 has a structure as shown in FIG. 3 and obtains the final target engine speed (NESPRF).

As shown in FIG. 3, the throttle opening (TH
R), the vehicle speed (NCO) value, and the shift operation, the steady-state target engine speed (NESPR) is set (201).

Set target engine speed (NESP
R) is subjected to the transient correction according to the driving operation and the traveling state of the vehicle (202), and becomes the final target engine rotation speed (NESPRF) subjected to the transient correction.

Then, the actual engine speed (NE)
Is the final target engine speed (NES
The engine speed control, that is, the gear shift control is performed by adjusting the gear ratio so as to match PRF).

That is, the final target engine speed (N
ESPRF) adjusts the ratio solenoid duty Ur as the gear ratio based on the neutral value Un of the ratio solenoid duty Ur after the PI control (203) by the integrated value and the belt slip prevention processing (204) are performed. .

Target engine speed (NESPR)
When setting the engine speed, the map (RACRVT) (see FIG. 5) having the throttle opening (THR) as a factor is used to determine the engine speed (NESP) with respect to the throttle opening (THR).
RT), and the upper limit value (NESPRH) and the lower limit value (NESPRL) of the engine speed (NESPRT) with respect to the throttle opening (THR) from the map (RACRVH, RACRVL) (see FIG. 6) having the vehicle speed (NCO) as a factor. ) And throttle opening (THR)
The target engine rotation speed (NESPR) is set by limiting the engine rotation speed (NESPRT) to the upper limit value (NESPRH) and the lower limit value (NESPRL).

A map (RACRVT) having a throttle opening (THR) as a factor and a map (RACRVH, RACRVL) having a vehicle speed (NCO) as a factor are provided for each shift position and have the same throttle opening. (T
HR) and vehicle speed (NCO), if the shift position is different, the target engine speed (NESP)
The value of R) is different.

Further, the target engine speed (NESP
In the transient correction of R), the target engine speed (NESPR) is filtered (301) as shown in FIG.
The processing value is set to NESPF, and the change amount of the final target engine rotation speed (NESPRF) per unit time is a limit value, that is, the upper limit value (RATUP) of the change amount of the final target engine rotation speed (NESPRF) per unit time. This is performed by rate limit control (302) that limits with the lower limit value (RATLO).

In the rate limit control (302), the final target engine speed (NESPR) per unit time set by the driving operation and the running state of the vehicle.
As is clear from FIG. 4, the lower limit value (RATLO) (303) and the upper limit value (RATUP) (304) of the change amount of F) are the last final target engine speed (NESPR).
F), that is, it is set in consideration of NESPRN.

When the throttle opening (THR) is suddenly increased by a driving operation or when a shift operation is performed, rate limit control (transient control) is performed with a limit value larger than a normal limit value.

In addition to the above-mentioned normal control, the control means 90 has the difference (ER) between the engine speed (NE) and the steady-state target engine speed (NESPR).
R) is obtained, and the upper limit value (RATUP) and the lower limit value (RATLO) of the change amount of the final target engine speed (NESPRF) per unit time are set by this difference (ERR), and according to the difference (ERR) The upper limit value (RA of the amount of change in the final target engine speed (NESPRF) per unit time
TUP) and the lower limit value (RATLO) are respectively changed to control the engine speed (NE) so as to improve the followability with respect to the target engine speed (NESPR) in the steady state.

Then, the upper limit value (RATU) of the amount of change in the final target engine rotation speed (NESPRF) per unit time is calculated.
P) and the lower limit value (RATLO) are set by a rate limit map as shown in FIG.

Further, as shown in FIG. 2, an input shaft rotation detection gear 102 is provided outside the first housing 20, and a first rotation detector on the input shaft side is provided in the vicinity of an outer peripheral portion of the input shaft rotation detection gear 102. 104 is provided. An output shaft rotation detection gear 106 is provided outside the second housing 22, and a second rotation detector 108 on the output shaft side is provided near the outer peripheral portion of the output shaft rotation detection gear 106. The detection signals of the first rotation detector 104 and the second rotation detector 108 are output to the control means 90 and used to grasp the engine speed and the belt ratio.

The output clutch 1 is connected to the hydraulic clutch 74.
A third rotation detector 11 for detecting the rotation of the final output shaft is provided in the vicinity of the outer peripheral portion of the output transmission gear 110.
Two are provided. That is, this third rotation detector 112
Is for detecting the rotation of the reduction gear, the differential gear, the drive shaft, and the final output shaft directly connected to the tire, and is capable of detecting the vehicle speed. In addition, the second rotation detector 10
8 and the third rotation detector 112, the hydraulic clutch 74
It is possible to detect the rotation of the input shaft and the output shaft, and to detect the clutch slip amount.

Next, the operation of this embodiment will be described.

In the continuously variable transmission 2, as shown in FIG. 2, the oil pump 30 located on the rotary shaft 18 operates in response to the rotation of the rotary shaft 18, and the oil in the oil pan 32 is filtered by the oil filter. Inhaled via 34. The line pressure, which is the pump pressure, is controlled by the line pressure control valve 54. If the amount of leakage from this line pressure control valve 54, that is, the escape amount of the line pressure control valve 54 is large, the line pressure will be low, and conversely, it will be small. If so, the line pressure becomes higher.

The operation of the line pressure control valve 54 is controlled by a dedicated second three-way solenoid valve 60, and the line pressure control valve 54 operates following the operation of the second three-way solenoid valve 60. The second three-way solenoid valve 60 is controlled at a constant frequency duty ratio. That is, the duty ratio of 0% means a state in which the second three-way solenoid valve 60 does not operate at all, the output side is connected to the atmosphere side, and the output hydraulic pressure becomes zero. In addition, the duty ratio 10
0% means that the second three-way solenoid valve 60 operates and the output side conducts to the input side, and the maximum output hydraulic pressure is the same as the control pressure. That is, the output hydraulic pressure is changed by changing the duty ratio of the second three-way solenoid valve 60. Therefore, the characteristic of the second three-way solenoid valve 60 is that the line pressure control valve 54 can be operated in an analog manner.
The line pressure can be controlled by arbitrarily changing the duty ratio of 0. The operation of the second three-way solenoid valve 60 is controlled by the control means 90.

The primary pressure for shift control is controlled by the primary pressure control valve 44, and like the line pressure control valve 54, the operation of the primary pressure control valve 44 is controlled by the dedicated first three-way solenoid valve 52. There is. This first
The three-way solenoid valve 52 is used for conducting the primary pressure to the line pressure or conducting the primary pressure to the atmosphere side, and conducting the line pressure to shift the belt ratio to the full over driver side or to the atmosphere side. It is to move to the full low side.

Clutch pressure control valve 6 for controlling the clutch pressure
No. 2 connects with the line pressure side when the maximum clutch pressure is required, and with the atmosphere side when the minimum clutch pressure is required. This clutch pressure control valve 62, like the line pressure control valve 54 and the primary pressure control valve 44,
Since the operation is controlled by the dedicated third three-way solenoid valve 68, description thereof will be omitted here. The clutch pressure varies within the range from the minimum atmospheric pressure (zero) to the maximum line pressure.

There are five patterns for controlling the clutch pressure, for example. (1), Neutral mode …… When the hydraulic clutch is completely disengaged when the shift position is N or P, the clutch pressure is the minimum pressure (zero) (2), Hold mode …… The shift position is D or R and the throttle is released. If you do not want to drive, or if you want to reduce the engine torque by slowing down while driving, the clutch pressure is low enough to contact the clutch (3), normal start mode .................................... When attempting to do so, the clutch pressure can be prevented from rising and the vehicle can operate smoothly. An appropriate level according to the engine generated torque (clutch input torque) (4), special start mode …… (a), vehicle speed Is 8〓 / H or more, shift lever D →
Repeated use of N → D, or (b),
When decelerating operation, the brake state is released at 8〓 / H <vehicle speed <15〓 / H, (5), drive mode .......................................................................................................................................... There are five high levels with plenty of room to withstand.

The pattern (1) is performed by a dedicated switching valve (not shown) which is interlocked with the shift operation, and the other (2), (3), (4), and (5) are the first and second by the control means 90. The duty ratio control of the second and third three-way solenoid valves 52, 60, 68 is performed. In particular, in the state (5), the clutch pressure control valve 62 connects the seventh oil passage 64 and the tenth oil passage 72 to each other so that the maximum pressure is generated, and the clutch pressure becomes the same as the line pressure.

The primary pressure control valve 44, the line pressure control valve 54, and the clutch pressure control valve 62 are controlled by the output hydraulic pressure from the first, second, and third three-way solenoid valves 52, 60, 68, respectively. However, the control hydraulic pressure for controlling the first, second, and third three-way solenoid valves 52, 60, 68 is a constant hydraulic pressure adjusted by the constant pressure control valve 48. This control oil pressure is always lower than the line pressure, but is a stable and constant pressure. Further, the control oil pressure is also introduced into each of the control valves 44, 54, 62 to stabilize these control valves 44, 54, 62.

Next, the electronic control of the continuously variable transmission 2 will be described.

The continuously variable transmission 2 is hydraulically controlled, and in response to a command from the control means 90, an appropriate line pressure for holding the belt and transmitting torque, and a primary speed for changing the gear ratio (belt ratio). The pressure and the clutch pressure for surely connecting the hydraulic clutch 74 are secured.

Next, description will be made with reference to the flow chart for setting the target engine rotation speed in the steady state shown in FIG.

When the setting program starts (401), the map (R) based on the throttle opening (THR) in FIG.
The engine speed (NESPRT) with respect to the throttle opening (THR) is calculated from ACRVT), and the map (RACRVH, RA) based on the vehicle speed (NCO) in FIG.
The upper limit (NESPR) of the engine speed (NESPRT) from the CRVL) to the throttle opening (THR)
H) and the lower limit value (NESPRL) (402), and the engine speed (N) with respect to the throttle opening (THR)
ESPRT) and throttle opening (THR) engine speed (NESPRT) upper limit (NESPR)
H) is compared and judged (403).

In this comparison judgment (403), NES
When PRT <NESPRH, the throttle opening (T
Engine speed (NESPRT) with respect to HR) and engine speed (N with respect to throttle opening (THR))
ESPRT) lower limit value (NESPRL) is compared and determined (404). When NESPRT ≧ NESPRH, the engine speed (NESPRT) with respect to the throttle (THR) is set as the target engine speed (NESPR) in the steady state. The process proceeds to (405) and end (408).

If NESPRT> NESPRL in the above comparison judgment (404), the engine speed (NESP) with respect to the throttle opening (THR).
RT) is the steady state target engine speed (NESP
R) (406), transition to end (408), NE
When SPRT ≦ NESPRL, engine speed (NESPRT) with respect to throttle opening (THR)
The lower limit value (NESPRL) of the engine is set as the target engine speed (NESPR) in the steady state (407), and the end (408)
Shift to.

This will be described with reference to the flow chart for transient correction of the target engine speed shown in FIG.

Steady state target engine speed (NES
When the PR) transient correction program is started (501), the target engine rotation speed (NESPR) in the steady state is filtered to be NESPF (502).

Then, the change amount of the final target engine speed (NESPRF) per unit time is set to the upper limit value (RATU).
P) and the lower limit value (RATLO) are set (50
3).

In the setting process (503), as shown in FIG. 10, when the setting flowchart starts (503A), the difference between the steady state target engine speed (NESPR) and the actual engine speed (NE) ( ERR) is calculated (503B), and the upper limit value (RAT) of the change amount of the final target engine speed (NESPRF) per unit time according to the difference (ERR) is calculated from the rate limit map shown in FIG.
UP) and the lower limit (RATLO) are calculated (503C),
Transition to end (503D).

Next, the upper limit value (RATU) of the amount of change of the final target engine speed (NESPRF) per unit time
P) and the lower limit value (RATLO) are set (503), the target engine rotation speed (NESPF) in the steady state after filtering and the last final target engine rotation speed (N
ESPRN) is compared and judged (504).

Then, in the comparison judgment (504), NE
When SPR <NESPRN, the value obtained by subtracting the steady-state target engine speed (NESPF) after filtering from the last final target engine speed (NESPRN) and the final target engine speed (NES per unit time)
The process proceeds to the comparison judgment (505) with the lower limit value (RATLO) of the change amount of (PRF).

In the comparison judgment (504), NES
When PR ≧ NESPRN, the value obtained by subtracting the last final target engine rotational speed (NESPRN) from the filtered steady-state target engine rotational speed (NESPF) and the final target engine rotational speed per unit time (NESPN)
The process proceeds to the comparison judgment (506) with the upper limit value (RATUP) of the change amount of RF).

In the above comparison judgment (505), NE
If SPRN-NESPF> RATLO, then NES
The value of PRN-RATLO is set as the final target engine speed (NESPRF) (507), and NESP
If RN-NESPF ≤ RATLO, steady-state target engine speed (NESPF) after filtering
Is the final target engine speed (NESPRF) (508).

Further, in the above comparison judgment (506), if NESPF-NESPRN≤RATUP, the steady state target engine rotation speed (NESPF) after the filtering is changed to the final target engine rotation speed (NESP).
RF) and the process (508) is performed.
In the case of NESPRN> RATUP, the value obtained by adding the upper limit value (RATUP) of the variation amount of the final target engine rotation speed (NESPRF) per unit time to the last final target engine rotation speed (NESPRN) is added. (NESPRF) (509).

Then, each processing (507), (508),
(509) final target engine speed (NESPR
F) is the last final target engine speed (NESPR
N) is set (510), and the process is ended (511).

As a result, the shift control can be performed so as to change the limit value according to the difference between the target engine speed in the steady state and the actual engine speed, and the limit value suitable for the driving operation and the running state of the vehicle. Can be set to
It can improve drivability.

Further, it is practically advantageous that the change state of the engine generated torque can be easily reflected in the change of the vehicle speed.

Further, the control means 90 causes the normal P
By performing the I control, the reliability of the shift control can be improved.

Furthermore, since the control program of the control means 90 can be simplified, the memory capacity can be saved and the tuning operation can be facilitated, which is economically and practically advantageous.

[0064]

As described in detail above, according to the present invention, after the actual engine speed is transiently corrected to the target engine speed in the steady state obtained from the shift schedule map of the throttle opening and the vehicle speed. In the shift control method for a continuously variable transmission that performs shift control so as to match the final target engine rotation speed, the steady-state target engine rotation speed is filtered at the time of transient correction of the steady-state target engine rotation speed and Set the change amount of the final target engine rotation speed of at least by the limit value considering the last target engine rotation speed of the previous time, and change the limit value according to the difference between the target engine rotation speed in the steady state and the actual engine rotation speed. Since the shift control is performed to
It is possible to set a limit value suitable for the driving operation and the running state of the vehicle, which can improve drivability and
The change state of the engine generated torque is easily reflected in the change of the vehicle speed, which is practically advantageous. Moreover, the reliability of the shift control can be improved by performing the normal PI control. Furthermore, since the program can be simplified, the memory capacity can be saved and the tuning operation can be facilitated, which is economically and practically advantageous.

[Brief description of drawings]

FIG. 1A is a time chart of an actual engine rotation speed (NE) showing an embodiment of the present invention. (B) is a time chart of the difference (ERR) between the actual engine speed (NE) and the steady-state target engine speed (NESPR). (C) Final target engine speed per hour (NESP
6 is a time chart of an upper limit value (RATUP) of a change amount of RF) and a lower limit value (RATLO) of a change amount of a final target engine rotation speed (NESPRF) per hour.

FIG. 2 is a schematic diagram of a continuously variable transmission and a hydraulic circuit.

FIG. 3 is a block diagram of a shift control loop.

FIG. 4 is a block diagram of transient correction of a target engine rotation speed.

FIG. 5 shows a throttle opening (THR) and a target engine speed (N) in a steady state depending on the throttle opening (THR).
It is a figure which shows the relationship with ESPR).

FIG. 6 is a diagram showing a relationship between a vehicle speed (NCO) and an upper limit value (NESPRH) and a lower limit value (NESPRL) of a target engine rotation speed (NESPR) in a steady state.

FIG. 7 is a flowchart for setting a target engine rotation speed in a steady state.

FIG. 8 is a time chart of a target engine rotation speed in a steady state.

FIG. 9 is a flowchart for transient correction of a target engine speed in a steady state.

FIG. 10 is a flowchart for setting a rate limit.

FIG. 11 is a rate limit map.

[Explanation of symbols]

 2 continuously variable transmission 4 belt 6 driving side pulley 12 driven side pulley 18 rotating shaft 30 oil pump 38 first oil passage 40 second oil passage 42 pressure control valve means 44 primary pressure control valve 46 third oil passage 48 constant pressure control Valve 50 Fourth oil passage 52 First three-way solenoid valve for primary pressure control 54 Line pressure control valve 56 Fifth oil passage 58 Sixth oil passage 60 Second three-way solenoid valve for line pressure control 62 Clutch pressure control valve 64 Seventh oil Passage 66 Eighth oil passage 68 Third three-way solenoid valve for clutch pressure control 70 Ninth oil passage 72 Tenth oil passage 74 Hydraulic clutch 76 Eleventh oil passage 78 Pressure converter 90 Control means

Claims (1)

[Claims] 1. A groove width between the fixed pulley portion and a movable pulley portion mounted on the fixed pulley portion such that the fixed pulley portion can be moved toward and away from the fixed pulley portion is increased or decreased by hydraulic pressure and wound around the both pulleys. Decrease the radius of gyration of the belt and match the actual engine speed to the final target engine speed after the transient correction is added to the steady-state target engine speed obtained from the shift schedule map of throttle opening and vehicle speed. In a shift control method of a continuously variable transmission for performing shift control to
At the time of transient correction of the target engine speed in the steady state, the target engine speed in the steady state is filtered, and the change amount of the final target engine speed per unit time is limited considering at least the last final target engine speed. A shift control method for a continuously variable transmission, wherein the shift control is performed by changing the limit value according to a difference between a target engine rotation speed in a steady state and an actual engine rotation speed.