JP3095197B2 - Shift control method 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 method for a continuously variable transmission, and more particularly, to a shift control for a continuously variable transmission capable of performing appropriate shift control when a final target engine rotation speed becomes equal to or lower than a predetermined value. About the method.

[0002]

2. Description of the Related Art In a vehicle, a transmission is interposed between an internal combustion engine and driving wheels. In this transmission, the driving force of the drive wheels and the traveling speed are changed in accordance with the traveling conditions of the vehicle which change over a wide range, and the performance of the internal combustion engine is sufficiently exhibited. The transmission is formed between both pulley parts of a pulley having, for example, a fixed pulley part fixed to a rotating shaft and a movable pulley part attached to the rotating shaft so as to be able to approach and separate from the fixed pulley part. There is a continuously variable transmission that changes the groove width by hydraulic pressure to reduce or increase the radius of rotation of the belt wound around the pulley, transmits power, and changes the belt ratio (speed ratio).

[0003] Some continuous variable transmissions have a hydraulic clutch for interrupting power by hydraulic pressure. The hydraulic clutch is controlled in various control modes based on signals such as an engine speed and a carburetor throttle valve opening.

In the continuously variable transmission, for example, a shift control for adjusting a gear ratio so as to make the actual engine speed match the final target engine speed by, for example, adding transient correction to obtain the final target engine speed. There is. Rate limit control is a method for obtaining a final target engine speed by transiently correcting the target engine speed in a steady state. Rate limit control limits the amount of change in the final target engine speed per unit time. As the rate limit control, there is a transient control for performing the rate limit control with a value larger than a normal change amount and a control value. The transient control when the throttle opening sharply increases is the throttle transient control. The transient control at the time of the shift operation is the shift transient control.

[0005] Further, there is one disclosed in Japanese Patent Publication No. 4-28947. Japanese Patent Publication No. 4-28947 discloses a method in which a control target value is determined based on an actual acceleration operation amount from a predetermined relationship, and an engine speed or a gear ratio follows the control target value. In a transient state in which the acceleration operation member of the vehicle is rapidly operated, the transient state changes more slowly than the control target value and at least changes in relation to the operation speed of the accelerator pedal of the vehicle. The time control target value is set instead of the control target value.

[0006]

By the way, in the conventional shift control method for a continuously variable transmission, as shown in FIG. 20, when the throttle opening (THR) is suddenly closed or when the shift position is low (L position). When the operation is switched from the drive to the drive (D position), the target engine speed (NE
SPR) decreases sharply.

This steady state target engine speed (N
In response to the change of the ESPR, the final target engine rotation speed (NESPRF) after the transient correction decreases rapidly.

Further, since the engine speed (NE) is controlled so as to match the final target engine speed (NESPRF), the engine speed (NE) also sharply decreases.

In general, proportional-integral-derivative (PID) control is used to make the engine speed (NE) equal to the final target engine speed (NESPRF).

However, the final target engine speed (NE)
When the change tendency of the SPRF changes suddenly, the follow-up property becomes worse as the degree of dependence on the integral control becomes higher. This is because a response delay occurs due to accumulation of the integral amount.

As a result, as shown by a symbol A in FIG. 14, there is a fear that an undershoot of the engine speed (NE) may occur, causing engine stall or deteriorating running feeling, which is disadvantageous for practical use. Is disadvantageous.

[0012]

SUMMARY OF THE INVENTION Accordingly, in order to eliminate the above-mentioned disadvantages, the present invention is directed to a pulley portion comprising a fixed pulley portion and a movable pulley portion which is detachably attached to the fixed pulley portion. The steady-state target obtained by increasing or decreasing the groove width between the ones by hydraulic pressure to decrease or increase the rotation radius of the belt wound around the two pulleys, and obtaining the actual engine rotation speed from a shift schedule map between the throttle opening and the vehicle speed. In the shift control method for a continuously variable transmission, the shift control is performed to match the final target engine speed after the transient correction for limiting the amount of change of the target engine speed is added to the engine speed. When the final target engine rotational speed later becomes equal to or less than a predetermined value set in advance, the direction of the transient correction change that limits the amount of change in the target engine rotational speed during transient correction is reduced. Characterized by shift control so as to reduce the control value gently smaller towns final target engine rotational speed.

[0013]

According to the invention described above, when the final target engine speed after the transient correction is reduced to a predetermined value or less, the amount of change in the target engine speed during the transient correction is limited. The control is performed to reduce the transient correction change amount in the decreasing direction, to reduce the final target engine rotational speed gently, and to prevent unnecessary decrease in the engine rotational speed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 19 show an embodiment of the present invention. In FIG. 2, 2 is a continuously variable transmission, 4 is a belt, 6 is a driving pulley, 8 is a driving fixed pulley piece,
10 is a drive side movable pulley piece, 12 is a driven side pulley,
14 is a driven-side fixed pulley part, and 16 is a driven-side movable pulley part. As shown in FIG. 2, the driving pulley 6 includes a driving fixed pulley piece 8 that is fixed to a rotating shaft 18 that is rotated by a prime mover, and the rotating shaft that is movable in the axial direction of the rotating shaft 18 and cannot rotate. And a drive-side movable pulley piece 10 mounted on the drive pulley 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 14 and a driven side movable pulley portion 16.

A first and a second housing 20 are attached to the driving side movable pulley portion 10 and the driven side movable pulley portion 16.
22 are respectively mounted on the first and second hydraulic chambers 2.
4 and 26 are respectively formed. The second hydraulic chamber 26 on the driven side
A pressing spring 28 for urging the driven-side movable pulley piece 16 toward the driven-side fixed pulley piece 14 is provided therein.
Is provided.

An oil pump 30 is provided at an end of the rotating shaft 18. The oil pump 30 supplies the oil in the oil pan 32 through an oil filter 34 to first and second oil passages 38 and 40 constituting 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 as a speed change control valve constituting a pressure control means 42 for controlling a primary pressure as an input shaft sheave pressure is provided. A third oil passage 46 communicating with the second oil passage 40 closer to the oil pump 30 than the primary pressure control valve 44 applies a line pressure (generally, 5 to 25 ° / 〓 ² ) to a constant pressure (for example, 3 to 4).圧 / 〓 ² ) Constant pressure control valve 4
8 are provided. Further, the primary pressure control valve 44 includes:
A first three-way solenoid valve 52 for primary pressure control is connected via a fourth oil passage 50.

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

Further, a clutch pressure control valve 62 for controlling the clutch pressure is provided in the second oil passage 40 on the second hydraulic chamber 26 side of the portion where the line pressure control valve 54 communicates with the fifth oil passage 56. Is provided using the other end of the branch. This clutch pressure control valve 62 has a third three-way solenoid valve 6 for clutch pressure control via an eighth oil passage 66.
8 is communicated.

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, the second three-way solenoid valve 60 for line pressure control, the clutch pressure control valve 62, and the third three-way solenoid valve 68 for clutch pressure control are connected to each other by a ninth oil passage 70.

The clutch pressure control valve 62 is in communication 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 communicated with the pressure transducer 78 via the eleventh oil passage 76 on the way. The pressure transducer 78 can directly detect the oil pressure when controlling the clutch pressure in the hold and start modes, and makes the detected oil pressure coincide with the target clutch pressure. In the drive mode, 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 comprises 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 as an electronic control unit for inputting various conditions such as a throttle opening degree of a carburetor (not shown) and an engine rotation of the vehicle and changing a duty ratio to perform a shift control is provided. 90
The first three-way solenoid valve 5 for primary pressure control
2. It is configured to control opening and closing operations of a second three-way solenoid valve 60 for controlling line pressure and a third three-way solenoid valve 68 for controlling clutch pressure, and to supply power to the pressure converter 78. In addition, various signals input to the control means 90 and the function of the input signal will be described in detail. A shift lever position detection signal... P, R, N, D, L, etc. Required line pressure, belt ratio, clutch control, carburetor throttle opening detection signal …… Detects engine torque from memory previously input into the program, determines target belt ratio or target engine speed, carburetor idle position Detection signal …… Improves accuracy in correcting and controlling the carburetor throttle opening sensor, Accelerator operation signal …… Detects the driver's will based on the depression of the accelerator pedal, determines the control direction when driving or starting, and brakes Signal …… Detects whether the brake pedal is depressed or not, and controls clutch disengagement etc. Decide method, power mode option signal …… Sports (or economy) performance of the vehicle
There is an option to use it.

When the final target engine speed after the transient correction is reduced to a predetermined value or less, the control means 90 limits the amount of change in the target engine speed during the transient correction. The shift control is performed so as to reduce the change direction control value of the change amount and decrease the final target engine rotational speed gently.

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

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

The set target engine speed (NES)
PR) is subjected to transient correction based on the driving operation and the running state of the vehicle (202), and becomes the final target engine speed (NESPRF) subjected to the transient correction.

Then, the actual engine speed (NE)
Target transient engine speed (NES)
(PRF) to adjust the gear ratio so as to perform engine rotation control, that is, gear shift control.

That is, the final target engine speed (N
ESPRF) performs ratio integral (PI) control (203) and belt slip prevention processing (204), and then adjusts the ratio solenoid duty Ur that becomes the gear ratio based on the neutral value Un of the ratio solenoid duty Ur. I have.

The target engine speed (NESPR)
When setting the throttle opening (THR), a map (RACRVT) (see FIG. 4) using the throttle opening (THR) as a factor is used to determine the engine speed (NESP) for the throttle opening (THR)
RT) and the upper limit value (NESPRL) and the lower limit value (NESPRL) of the engine speed (NESPRT) with respect to the throttle opening (THR) from the maps (RACRVH, RACRVL) (see FIG. 5) using the vehicle speed (NCO) as a factor. ) And the throttle opening (THR)
The target engine speed (NESPR) is set by restricting the engine speed (NESPRT), the upper limit value (NESPRH), and the lower limit value (NESPRL) with respect to.

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

Further, the target engine speed (NESP)
In the transient correction of R), as shown in FIG. 7, a filter process (301) is performed on the target engine speed (NESPR),
The processing value is NESPF, and the amount of change in the final target engine speed (NESPRF) per unit time is a control value, that is, the increasing direction control value of the amount of change in the final target engine speed (NESPRF) per unit time. The upper limit value (RATUP) and the lower limit value (RA
TLO) and rate limit control (302)
And so on.

In this 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 is set.
The lower limit value (RATLO) (303) and the upper limit value (RATUP) (304) of the variation of F) are, as apparent from FIG. 7, the last final target engine speed (NESPR).
F), that is, set in consideration of NESPRN (FIG. 8)
reference). The decreasing direction control value (R
ATLO) is set to a minimum value regardless of the magnitude of a general rate limit control value (RATLON) and a shift transient control value (RATLOS) when the engine speed (NE) is lower than a predetermined value (NETRL). RA
Let TLO (MINRL) be RATLO.

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 control value larger than a normal control value.

Further, in addition to the above-described normal control, the control means 90 obtains from the expression | NESPR-NESPRF |
PR), the final target engine speed (NESPRF), the difference (absolute value) (ERRN), and the expression NESPRU-NESPRF, that is, the engine speed trigger (NESPRU) and the final target engine speed (NESPRF) during throttle transient control. And the difference (ERRT) are obtained, and the upper limit (RATUP) and the lower limit (RATLO) of the amount of change of the final target engine speed (NESPRF) per unit time are set by the difference (ERRN, EERT). Target engine speed (NESPRF) per unit time according to the difference (ERRN, EERT)
Upper limit (RATUP) and lower limit (RATL)
O), and a function of controlling the engine rotational speed (NE) so as to improve the ability to follow the steady-state target engine rotational speed (NESPR).

Then, the upper limit value (RATU) of the amount of change in the final target engine speed (NESPRF) per unit time is calculated.
P) and the lower limit (RATLO) are shown in FIGS.
As shown in FIG. 6, this is performed by a rate limit map.

As shown in FIG. 2, an input shaft rotation detecting gear 102 is provided outside the first housing 20, and a first rotation detector on the input shaft side is provided near an outer peripheral portion of the input shaft rotation detecting gear 102. 104 are 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 an outer peripheral portion of the output shaft rotation detection gear 106. Detection signals from the first rotation detector 104 and the second rotation detector 108 are output to the control means 90 and are used to determine the engine speed and the belt ratio.

The power transmission gear 1 is connected to the hydraulic clutch 74.
A third rotation detector 11 for detecting the rotation of the final output shaft is provided near the outer peripheral portion of the output transmission gear 110.
2 are provided. That is, the third rotation detector 112
Detects the rotation of a reduction gear, a differential, a drive shaft, and a final output shaft directly connected to a tire, and enables detection of a vehicle speed. In addition, the second rotation detector 10
8 and the third rotation detector 112, the hydraulic clutch 74
Can detect the rotation of the input shaft and the output shaft, and can 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, an oil pump 30 located on the rotating shaft 18 operates according to the rotation of the rotating shaft 18, and the oil in the oil pan 32 is filtered by an oil filter. Inhaled via. The line pressure, which is the pump pressure, is controlled by the line pressure control valve 54. If the amount of leakage from the line pressure control valve 54, that is, the relief amount of the line pressure control valve 54, is large, the line pressure becomes low, and conversely, the line pressure becomes small. If the line pressure is high.

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% is 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 oil pressure becomes zero. Also, the duty ratio 10
When it is 0%, the second three-way solenoid valve 60 operates, the output side is connected to the input side, and the maximum output oil pressure is the same as the control pressure. That is, the output oil pressure is changed by changing the duty ratio to the second three-way solenoid valve 60. Therefore, the characteristics of the second three-way solenoid valve 60 allow the line pressure control valve 54 to operate 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 a primary pressure control valve 44, and the operation of the primary pressure control valve 44 is also controlled by a dedicated first three-way solenoid valve 52, similarly to the line pressure control valve 54. I have. This first
The three-way solenoid valve 52 is used to conduct the primary pressure to the line pressure or to conduct the primary pressure to the atmosphere side, and to conduct the line pressure to shift the belt ratio to the overdriver side or to conduct the belt ratio to the atmosphere side. To the full low side.

Clutch pressure control valve 6 for controlling clutch pressure
Reference numeral 2 denotes a connection to the line pressure side when the maximum clutch pressure is required, and a connection to the atmosphere side when the minimum clutch pressure is required. This clutch pressure control valve 62 is also similar to 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, the description is omitted here. The clutch pressure varies within a range from a minimum atmospheric pressure (zero) to a maximum line pressure.

There are, for example, five patterns for controlling the clutch pressure. (1) Neutral mode: When the shift position is N or P and the hydraulic clutch is completely disengaged, the clutch pressure is the minimum pressure (zero). (2) Hold mode: When the shift position is D or R, release the throttle. If there is no intention to drive, or if you want to decelerate during running and want to cut off the engine torque, the clutch pressure is low enough to make the clutch contact (3), normal start mode .... When trying to do so, the clutch pressure is prevented from being blown up by the engine and an appropriate level according to the engine generated torque (clutch input torque) that can operate the vehicle smoothly (4), special start mode ... (a), vehicle speed When the gear is 8Ｄ / H or more, shift the lever to D →
(B) Releasing the brake state at 8〓 / H <vehicle speed <15〓 / H during deceleration operation, (5) Drive mode …… Complete running state When the clutch is completely engaged, there are five high levels of clutch pressure that can afford enough to withstand the engine torque.

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 control means 90. This is performed by controlling the duty ratio of the second and third three-way solenoid valves 52, 60 and 68. In particular, in the state (5), the seventh oil passage 64 and the tenth oil passage 72 are communicated by the clutch pressure control valve 62 so that a 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 output hydraulic pressures from first, second, and third three-way solenoid valves 52, 60, and 68, respectively. However, the control oil pressure for controlling the first, second and third three-way solenoid valves 52, 60 and 68 is a constant oil 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. The control oil pressure is also introduced into each of the control valves 44, 54, 62 to stabilize the 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 is controlled by a command from the control means 90 to change an appropriate line pressure for belt holding and torque transmission and a primary gear for changing a gear ratio (belt ratio). The pressure and the clutch pressure for securely connecting the hydraulic clutch 74 are each secured.

Referring to FIG. 1, when the throttle opening (THR) is suddenly closed, the throttle opening (THR)
R), the steady-state target engine speed (NESPR) and the final target engine speed (NESP)
RF) and decrease rapidly, but NESPRF ≦ NET
At RL, RATLO = MINRL, so that the final target engine speed (NESPRF) gradually decreases.

For this reason, the decreasing state of the engine speed (NE) first decreases rapidly at first, but gradually decreases when the final target engine speed (NESPRF) becomes equal to or lower than the RATLO engine speed trigger (NETRL). Is what you do.

At this time, the final target engine speed (N
The undershoot of the engine speed (NE) as shown in FIG. 1B may occur due to a sudden change in the change tendency of the ESPRF).
E) is a sufficiently high value, and there is no problem that causes engine stall or deterioration of running feeling.

Next, a description will be given along a flowchart for setting the target engine speed in the steady state in FIG.

When the setting program starts (401), the engine rotation speed (NESPRT) with respect to the throttle opening (THR) is obtained, and the engine rotation speed (NESPRT) with respect to the throttle opening (THR).
Upper limit (NESPRH) and lower limit (NESPRL)
(402), the engine speed (NESPRT) for the throttle opening (THR) and the engine speed (NESPRT) for the throttle opening (THR).
Is compared with the upper limit value (NESPRH) (403).

In this comparison judgment (403), NES
If PRT <NESPRH, the throttle opening (T
HR) and engine speed (NSPRT) with respect to throttle opening (THR).
The process proceeds to a comparison judgment (404) with the lower limit value (ESPRL) of the ESPRT). If NESPRT ≧ NESPRH, the upper limit value (NESPRH) of the engine speed (NESPRT) with respect to the throttle (THR) is set to the target engine in the steady state. Rotational speed (NESPR) (40
5), and proceed to the end (408).

In the comparison judgment (404), if NESPRT> NESPRL, the engine speed (NESP) with respect to the throttle opening (THR) is determined.
RT) to the steady state target engine speed (NESP)
R) (406), and the process proceeds to the end (408).
If SPRT ≦ NESPRL, the engine speed (NESPRT) with respect to the throttle opening (THR)
The lower limit value (NESPRL) is set as the steady state target engine speed (NESPR) (407), and the process ends (408).
Move to

A description will be given with reference to the flowchart of FIG. 9 for correcting the transient of the target engine speed.

The steady state target engine speed (NES)
When the transient correction program (PR) is started (501), the target engine speed (NESPR) in a steady state is filtered and set to NESPF (502).

Then, an upper limit value (RATUP) which is an increasing direction control value and a lower limit value (RATLO) which is a decreasing direction control value of the amount of change in the final target engine speed (NESPRF) per unit time are set (FIG. 2). 503).

As shown in FIG. 10, in the setting process (503), when the flowchart for setting the upper limit (RATUP) starts (601), the equation | NESPR-NESPRF |
PR), the final target engine rotational speed (NESPRF) and the difference (absolute value) (ERRN) are obtained (602), and the general upper limit is obtained from a RATUPN map which is a general upper limit (RATUP), that is, RUCRVN (ERRN) in FIG. (R
ATUPN) (603).

Next, it is determined whether or not the traveling mode is LOW (604). If this determination (604) is NO, the determination is made as to whether or not the traveling mode is POWER (605). If the judgment (604) is YES, RACRVUL which is the RACRVU at the time of LOW is shifted.
(THR) is set as an engine speed trigger (NESPRU) at the time of throttle transient control (606).

On the other hand, if the determination (605) of whether or not the traveling mode is POWER is NO, ECONIMY
RACRVUE (THR), which is the RACRVU at the time, is set as the engine speed trigger (NESPRU) at the time of throttle transient control (607). If the determination (605) is YES, RACRVUP (THR), the RACRVU at the time of POWER, is throttled. An engine speed trigger (NESPRU) at the time of transient control is set (608).

Then, the final target engine speed (NESPRF) subjected to the transient correction is compared with the engine speed trigger (NESPRU) at the time of the throttle transient control (609), and NESPRF <NESPRU.
In the case of, the difference (ERRT) is calculated by the expression NESPRU-NESPRF (610), and RATUPT
From the map RUCRVT (ERRT) to the upper limit value (RATUP) R at the time of throttle transient control
ATUPT is obtained (611), and the process proceeds to shift transient control setting (612).

In the comparison judgment (609), NE
If SPRF ≧ NESPRU, 0 (zero) is set to RA
TUPT is set (613), and the process proceeds to the setting of shift transient control (612).

Next, a RATUPS flag (RATUP), which is the upper limit value (RATUP) during shift transient control, is set.
FLGU) is set (SET) or cleared (CLE)
AR) is determined (614), and in the determination (614), the RATUPS flag (RATF
LGU) is set (SET), RA
A value obtained by subtracting 1 from the TUPS timer (TIMESU) is used as the RATUPS timer (TIMESU) (61).
5) In the judgment (614), if the RATUPS flag (RATFLGU) is cleared (CLEAR), 0 (zero) is set as RATUPS, and
0 (zero) is used as a RATUPS timer (TIMESU), and a RATUPS flag (RATFFLGU) is cleared (CLEAR) (616).

A value obtained by subtracting 1 from the RATUPS timer (TIMESU) is used as the value of the RATUPS timer (TIMES).
After the processing (615) for U), a comparison determination is made between the RATUPS timer (TIMESU) and 0 (zero) (61).
7) If TIMESU> 0, RUCRVS
(ERRN) is set to RATUPS (618), and TIME
If SU ≦ 0, the process proceeds to the above-described processing (616).

Also, RUCRVS (ERRN) is changed to RAT
After the process for setting the UPS (618), a comparison is made between the target engine speed (NESPR) in the normal state and the final target engine speed (NESPRF) + RATUPS (6).
19) When NESPR> NESPRF + RATUPS, MAX (RATUPN, RATUPS, RATUPS)
TUPT) is selected as the RATUP (620), and the setting program is terminated (621).

Further, NESPR ≦ NESPRF + RAT
In the case of the UPS, the processing shifts to the above-described processing (616). When this processing (616) ends, MAX (RAT
After the process of setting the largest one among UPN, RATUPS, RATUPT) to RATUP (620), the process proceeds to the end of the setting program (621).

Further, as shown in FIG. 11, the lower limit (R
When the ATLO) setting flowchart starts (701), the final target engine speed (NESPRF) and RA
A comparison is made (702) with the TLO engine speed trigger (NETRL), and if NESPRF> NETRL, the expression | NESPR-NESPRF |
PR), the final target engine speed (NESPRF) and the difference (absolute value) (ERRN) are obtained (703), and the NESP
MI that is the minimum RATLO when RF ≦ NETRL
The NRL is set to RATLO (704), and the process proceeds to the end of the setting program (714).

Then, after the process of calculating the difference (absolute value) (ERRN) (703), the RL of the RATLON map
CRVN (ERRN) is a general RATLO RAT
LON is set (705), and the process proceeds to the setting of shift transient control (706).

Next, the RATLOS flag (RATFL)
GL) is set (SET) or cleared (CLEA)
R) is determined (707), and in the determination (707), the flag for RATLOS (RATF
LGL) is set (SET), RA
A value obtained by subtracting 1 from the TLOS timer (TIMESL) is used as the RATLOS timer (TIMESL) (70
8) In the judgment (707), when the RATLOS flag (RATFGL) is cleared (CLEAR), 0 (zero) is set to RATLOS which is RATLO at the time of shift transient control, and 0 (zero) is set. A timer for RATLOS (TIMESL) is set, and a flag for RATLOS (RATFLGL) is cleared (CLEAR) (709).

The value obtained by subtracting 1 from the RATLOS timer (TIMESL) is used as the value of the RATLOS timer (TIMES).
L), the processing (708) is performed, and a comparison is made between the RATLOS timer (TIMESL) and 0 (zero) (71).
0), and if TIMESL> 0, RUCRVS
(ERRN) is set to RATLOS (711), and TIME
If SL ≦ 0, the flow shifts to the above-described processing (709).

Further, RUCRVS (ERRN) is changed to RAT
After the process of setting LOS (711), the target engine speed (NESPR) in the normal state and the final target engine speed (NESPRF) -RATLOS are compared and determined (7).
12) If NESPR <NESPRF-RATLOS, the largest one from MAX (RATLON, RATLOS) is selected as RATLO (713),
The setting program ends (714).

Further, NESPR ≧ NESPRF-RAT
In the case of the LOS, the process proceeds to the above-described processing (709). When this processing (709) ends, MAX (RAT
LON, RATLOS)
After the process for setting LO (713), the process proceeds to the end of the setting program (714).

Then, the upper limit value (RATU) of the amount of change of the final target engine speed (NESPRF) per unit time is calculated.
P) and the lower limit (RATLO) (503), the steady state target engine speed (NESPF) after the filter processing and the last final target engine speed (N
ESPRN) is compared (504).

Then, in the comparison judgment (504), NE is set.
If SPR <NESPRN, a value obtained by subtracting the steady-state target engine speed (NESPF) after filtering from the last final target engine speed (NESPRN) is calculated as the final target engine speed (NESRP) per unit time.
The process proceeds to a comparison judgment (505) with the lower limit (RATLO) of the variation of PRF).

In the comparison judgment (504), the NES
When PR ≧ NESPRN, a value obtained by subtracting the previous final target engine speed (NESPRN) from the target engine speed (NESPF) in the steady state after the filter processing and the final target engine speed (NESP) per unit time are used.
Then, the process proceeds to the comparison judgment (506) with the upper limit value (RATUP) of the change amount of RF).

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

In the above-mentioned comparison judgment (506), if NESPF-NESPRN ≦ RATUP, the steady-state target engine speed (NESPF) after the filter processing is changed to the final target engine speed (NESP).
RF) (508), and the NESPF-
If NESPRN> RATUP, a value obtained by adding the upper limit value (RATUP) of the variation of the final target engine speed (NESPRF) per unit time to the last final target engine speed (NESPRN) is used as the final target engine speed. (NESPRF) (509).

Then, each processing (507), (508),
(509) Final target engine speed (NESPR
F) to the last target engine speed (NESPR)
N) (510), and end (511).

Here, a flow chart for setting the shift transient control will be described with reference to FIG.

When the flow chart for setting the shift transient control starts (801), the processing shifts to a setting map as shown in FIG. 14 (802).

Then, in the setting map as shown in FIG. 14, it is determined whether or not the setting is the previous value Z ^-1 which is the setting map (RACRVL) of the previous lower limit value (NESPRL) of the target engine rotation speed ( 803), and if this determination (803) is NO, it is determined whether the setting is LO in the setting map as shown in FIG.
04).

If the judgment (803) is YES, the flow chart for setting the shift transient control is terminated (807).

If the above judgment (804) is NO,
Set the RATUPS flag (RATFLGU) (S
ET), and set TIMESU to TIMESU (80
5) The shift transient control setting flowchart is terminated (807), and if the judgment (804) is YES, the RATLOS flag (RATFFLGL) is set (SET), TIMESLLI is set to TIMESL (806), and shift is performed. This is the end of the transient control setting flowchart (807).

The symbols used in FIG. 12 will be described below. D: Shift position is drive L: Shift position is low ECONOMY: Travel mode is economy POWER: Travel mode is power LOW: Travel mode is low RACORVH at ECONOMY RACRVHP: RACRVH at POWER POWER RACRVHL: RACRVH at LOW RACRVLE: RACRVL at ECONOMY RACRVLEI: RACR at idle switch ON
VLI RACRVLP: RACRVL at POWER time RACRVLL: RACRVL at LOW time

Thus, as shown by the symbol B in FIG. 1, even if an undershoot of the engine speed (NE) occurs, the engine speed at this time is sufficiently high.
There is no danger of causing engine stall or deteriorating the running feeling, which is practically advantageous.

Further, since it can be dealt with only by changing the control program of the control means 90, no additional parts are required and the configuration can be kept simple, which is economically and practically advantageous.

Note that the present invention is not limited to the above-described embodiment, and various application modifications are possible.

For example, in the embodiment of the present invention, the control is started when the final target engine speed after the transient correction is reduced to a predetermined value or less.
As shown in FIG. 8, the minimum decreasing direction control value is set by using the final target engine speed as a factor, or as shown in FIG. 19, the minimum decreasing direction control value is set by using the engine speed as a factor. Is also possible.

[0090]

As described above in detail, according to the present invention, when the final target engine rotation speed after the transient correction becomes equal to or less than a predetermined value set in advance, the target engine rotation speed during the transient correction is changed. The shift control is performed to reduce the control value of the direction of decrease of the transient correction change amount that limits the change amount of
Even if an undershoot of the engine rotational speed occurs after the shift control, the engine rotational speed is sufficiently high, so that there is no fear of causing engine stall or deteriorating the running feeling, which is practically advantageous. In addition, since it can be dealt with only by changing the control program, no additional parts are required, the configuration can be kept simple, and it is economically and practically advantageous.

[Brief description of the drawings]

FIG. 1 is a time chart of shift control of a continuously variable transmission, (a) is a time chart of a throttle opening (THR), (b) is a time chart of an engine rotation speed (NE), and (c) is ERRN. = | NESPR-NESPRF
Is a time chart of |, and (d) is a time chart of a decreasing direction control value (RATLO) of a change amount of the final target engine rotation speed (NESPRF) per unit time.

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

FIG. 3 is a block diagram of shift control.

FIG. 4 shows a steady state target engine speed (N) based on a throttle opening (THR) and a throttle opening (THR).
FIG.

FIG. 5 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 steady-state target engine speed (NESPR).

FIG. 6 is a flowchart for setting a target engine rotation speed in a steady state.

FIG. 7 is a block diagram of transient correction of a target engine rotation speed.

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 rotation speed in a steady state.

FIG. 10 shows an increasing direction control value (RATU) of a change amount of a final target engine speed (NESPRF) per unit time.
It is a flowchart for setting of P).

FIG. 11 shows a decreasing direction control value (RATL) of a change amount of a final target engine speed (NESPRF) per unit time.
It is a flowchart for setting of O).

FIG. 12 shows various driving modes NESPRT, NESPR
It is a figure which shows the setting condition of H, NESPRL.

FIG. 13 is a flowchart for setting shift transient control.

FIG. 14 is a diagram showing a setting state of shift transient control.

FIG. 15 shows an increasing direction control value (RATU) of a change amount of a final target engine rotation speed (NESPRF) per unit time.
It is a map of P).

FIG. 16 shows a decreasing direction control value (RATL) of a change amount of a final target engine speed (NESPRF) per unit time.
O) is a map.

FIG. 17 is a map of an engine speed trigger (NESPRU) at the time of throttle transient control.

FIG. 18 is a map for setting a minimum decreasing direction control value according to another first embodiment of the present invention.

FIG. 19 is a map for setting a minimum decreasing direction control value according to a second embodiment of the present invention.

FIG. 20 is a time chart of a shift control of the continuously variable transmission according to the prior art of the present invention, in which (a) is a time chart of a throttle opening (THR), and (b) is a time of an engine speed (NE). Chart, (c) shows ERRN =
| NESPR-NESPRF | time chart,
(D) is the final target engine speed per unit time (N
ESPRF) change direction decrease value (RATLO)
It is a time chart.

[Explanation of symbols]

 2 Continuously Variable Transmission 4 Belt 6 Drive Pulley 12 Driven Pulley 18 Rotary 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 7 oil passage 66 eighth oil passage 68 third three-way solenoid valve for controlling clutch pressure 70 ninth oil passage 72 10th oil passage 74 hydraulic clutch 76 11th oil passage 78 pressure converter 90 control means

Continuation of the front page (56) References JP-A-64-16442 (JP, A) JP-A-2-2212671 (JP, A) JP-A-1-261550 (JP, A) JP-A-3-87845 (JP) , U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 9/00-9/26 F16H 59/00-63/48

Claims (1)

(57) [Claims] 1. A groove between a fixed pulley portion and a movable pulley portion attached to and detachable from the fixed pulley portion, between the two pulley portions is increased or decreased by hydraulic pressure to be wound around the two pulley portions. A transient correction that reduces the belt's radius of rotation and limits the actual engine speed to the steady-state target engine speed obtained from the shift schedule map between the throttle opening and the vehicle speed. in shift control method for a continuously variable transmission for shifting control so as to coincide with the final target engine rotational speed after the addition, the transient
When the final target engine rotation speed after the correction becomes equal to or less than a predetermined value set in advance, the control value for the direction of decrease of the transient correction change amount that limits the change amount of the target engine rotation speed during the transient correction is set to a small value. And finally set the final target engine speed
A shift control method for a continuously variable transmission, wherein the shift control is performed to reduce the speed.