JP2003083441A - Transmission controller for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve traveling performance in inertial traveling on a downward slope regardless of an operation state of a lockup clutch. SOLUTION: A continuously variable transmission continuously changes rotation of an input-side rotation body driven by an engine through a torque converter with the lockup clutch through a power transmission element and transmits the rotation to an output-side rotation body. When a vehicle has not less than a prescribed acceleration/deceleration in a state wherein an inertial traveling detection means detects the inertial traveling of the vehicle on the downward slope, a lower limit value of a target rotation speed for the inertial traveling of the input-side rotation body is set, and the lower limit value is corrected according to the operation state of the lockup clutch. A lower limit value change ratio is corrected according to the operation state of the lockup clutch, and the inertial traveling target rotation speed or the lower limit value change ratio is varied in respective engagement time, disengagement time and incomplete clutching time of the lockup clutch.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a continuously variable transmission, and more particularly to improving the running performance of the vehicle when the vehicle travels on a downhill road.

[0002]

2. Description of the Related Art As a continuously variable transmission used in vehicles such as automobiles, there are a belt type and a toroidal type. A belt type continuously variable transmission has an input-side primary pulley provided on an input shaft, an output-side secondary pulley provided on an output shaft, and a power transmission element such as a belt or a chain that is wound around these pulleys. Then, by changing the groove width of each pulley to change the winding diameter of the power transmission element, it is possible to continuously change the gear ratio and transmit the rotation of the input shaft to the output shaft.

In such a continuously variable transmission, the gear ratio is automatically controlled on the basis of parameters indicating operating conditions such as throttle opening and vehicle speed or engine speed. That is, the target primary pulley rotation speed is set by referring to the basic gear shift characteristic map based on this parameter, and the gear ratio is set so that the actual primary pulley rotation speed converges to this target primary rotation speed. According to the basic shift characteristic map, the smaller the throttle opening is, the higher the gear ratio is set. For this reason,
When the driver releases the accelerator pedal while traveling downhill, that is, when traveling downhill, the throttle opening becomes smaller, the gear ratio is set to the high speed side, and the target input speed decreases, so engine braking is controlled in the direction that does not work. Will be done.

Therefore, in the case where the accelerator pedal is released and the vehicle runs inertially, that is, when the vehicle is traveling on a downhill road instead of a flat road, the gear ratio is downshifted to the low speed side to change the engine speed or The gear ratio is controlled so that the engine brake is effective by making a correction so as to increase the primary speed. For example, in the continuously variable transmission disclosed in JP-A-8-21500, the gear ratio is increased / decreased to correct and control the engine brake so that the acceleration / deceleration is detected and converges to a predetermined acceleration / deceleration. I am trying.

[0005]

However, the acceleration / deceleration is detected during inertial running, and above a predetermined acceleration / deceleration, the target engine speed lower limit value or the primary speed lower limit value for inertial running is provided to obtain engine braking. In such a case, in the continuously variable transmission having the torque converter with the lockup clutch, the effect of engine braking differs depending on the slip ratio of the torque converter when the lockup clutch is engaged and when the lockup clutch is disengaged. Therefore, even if the engine speed lower limit value is set so that the optimum engine brake is obtained when the lockup is released, the optimum engine brake may not be obtained when the lockup is engaged and the driver may feel uncomfortable. .

An object of the present invention is to improve running performance when inertially running on a downhill road.

Another object of the present invention is to improve the traveling performance when inertially traveling on a downhill road regardless of the operating state of the lockup clutch.

[0008]

A transmission control device for a continuously variable transmission according to the present invention controls the rotation of an input side rotating body driven by an engine via a torque converter equipped with a lockup clutch via a power transmission element. A speed change control device for a continuously variable transmission that continuously changes and transmits to an output-side rotating body, including a vehicle speed detecting means for detecting a vehicle running speed, a throttle sensor for detecting a throttle opening, and a vehicle. Is inertially traveling on a downhill road, inertial traveling detection means for detecting an operating state of the lockup clutch, and inertial traveling detection means for causing the vehicle to inertially travel downhill. Is detected, the lower limit value setting means for setting the target rotational speed lower limit value for inertial traveling of the input side rotating body, and the operating state of the lockup clutch. In response characterized by having a lower limit value correction means for correcting the lower limit value.

A shift control device for a continuously variable transmission according to the present invention continuously changes the rotation of an input side rotating body driven by an engine via a torque converter equipped with a lockup clutch via a power transmission element. A transmission control device for a continuously variable transmission, which transmits to a rotating body on the output side by means of a vehicle speed detection means for detecting a traveling speed of the vehicle, a throttle sensor for detecting a throttle opening, and a vehicle inertially traveling on a downhill road. The inertial traveling detection means for detecting that the vehicle is running, the clutch operating state detection means for detecting the operating state of the lockup clutch, and the inertial traveling detection means for detecting that the vehicle is inertial traveling on a downhill road. Under the state, a lower limit value setting means for setting a target rotational speed lower limit value for inertial traveling of the input side rotating body, a change rate limiting means for limiting a change rate of the lower limit value, and Wherein the Tsu according to the operating state of the click-up clutch and a lower limit change rate correcting means for correcting the lower limit change rate.

In the shift control apparatus for a continuously variable transmission according to the present invention, the target rotational speed lower limit value for inertial traveling or the lower limit value change rate is different when the lockup clutch is engaged, disengaged, and half-clutch respectively. It is characterized by

The shift control device for a continuously variable transmission according to the present invention is characterized in that the lower limit value of the rotational speed for inertial traveling is set as a lower limit value of the gear ratio, and the lower limit change rate is set as a gear ratio change rate.

In the transmission control device for a continuously variable transmission according to the present invention, when the vehicle is inertially traveling on a downhill road, the lockup clutch of the torque converter is engaged and released. Since the different target rotational speed lower limit values for inertial traveling are set, the optimum engine braking force can be obtained regardless of the operation of the torque converter.

Further, when the lower limit value of the target rotational speed for inertial running is switched in the lockup released state or the engaged state, the rotational speed fluctuates stepwise and the lower limit value is set to a predetermined value in order to prevent a sudden change in the engine brake. Since the change rate is changed and the change rates are set to different values at the time of engagement and at the time of disengagement, an optimum engine brake change can always be obtained regardless of the lockup state.

If the lock-up clutch is slipping during the lock-up engagement, another rate of change is set, so that the primary rotation speed is prevented from largely changing while the lock-up clutch is slipping. Lock-up shock can be reduced.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing a drive system of a belt type continuously variable transmission as an example of the continuously variable transmission. In this continuously variable transmission, the rotation of a crankshaft 2 driven by an engine 1 and a torque converter 3 It has a drive-side primary shaft 5 that is transmitted through the forward-reverse switching device 4 and a driven-side secondary shaft 6 that is parallel to this.

The primary shaft 5 is provided with a primary pulley 7. The primary pulley 7 is a fixed pulley 7a integrated with the primary shaft 5, and the primary pulley 7 is opposed to the fixed pulley 7a in the axial direction by a ball spline or the like. And a movable pulley 7b slidably attached to the pulley, and the cone surface distance of the pulley, that is, the pulley groove width is variable.
The secondary shaft 6 is provided with a secondary pulley 8. The secondary pulley 8 has a fixed pulley 8a integrated with the secondary shaft 6, and a secondary pulley 6 facing the fixed pulley 8a in the axial direction in the same manner as the movable pulley 7b. And a movable pulley 8b slidably attached to the pulley, and the pulley groove width is variable.

Primary pulley 7 and secondary pulley 8
A belt 9 as a power transmission element is stretched between the two pulleys, and the groove width of both pulleys 7 and 8 is changed to change the ratio of the winding diameter of the belt 9 to each pulley. The rotation of the shaft 5 is steplessly changed in speed and transmitted to the secondary shaft 6. The winding diameter of the drive belt 9 around the primary pulley 7 is R
Assuming that p is p and the winding diameter around the secondary pulley 8 is Rs, the gear ratio, that is, the pulley ratio i is i = Rs / Rp.

The rotation of the secondary shaft 6 is transmitted to the drive wheels 12a and 12b through a gear train having a reduction gear and a differential device 11. In the case of front wheel drive, the drive wheels 12a and 12b are the front wheels. Becomes

A plunger 13 is fixed to the primary shaft 5 in order to change the groove width of the primary pulley 7.
A primary cylinder 14 that slidably contacts the outer peripheral surface of the plunger 13 is fixed to the movable pulley 7b, and a driving oil chamber 15 is formed by the plunger 13 and the primary cylinder 14. On the other hand, in order to change the groove width of the secondary pulley 8, a plunger 16 is fixed to the secondary shaft 6, and a secondary cylinder 17 slidably contacting the outer peripheral surface of the plunger 16 is fixed to the movable pulley 8b. A drive oil chamber 18 is formed by the plunger 16 and the secondary cylinder 17. Each groove width is set by adjusting the primary pressure Pp introduced into the drive oil chamber 15 on the primary side and the secondary pressure Ps introduced into the drive oil chamber 18 on the secondary side.

The hydraulic oil in the oil pan 20 is supplied to the respective drive oil chambers 15 and 18 by an oil pump 21 driven by an engine or an electric motor. The secondary pressure passage 22 connected to the outlet is communicated with the drive oil chamber 18 and the secondary pressure port of the secondary pressure regulating valve 23. This secondary pressure control valve 23
Secondary pressure Ps supplied to the drive oil chamber 18 by
Is adjusted to a pressure commensurate with the required transfer capacity of the belt 9.

The secondary pressure passage 22 is connected to the secondary pressure port of the primary pressure regulating valve 24 via the communication oil passage 25, and the primary pressure port of this primary pressure regulating valve 24 is connected to the primary side via the primary pressure passage 26. Is connected to the drive oil chamber 15. The primary pressure Pp is adjusted by the primary pressure adjusting valve 24 to a value according to the target gear ratio, the vehicle speed, etc., and the groove width of the primary pulley 7 is changed to control the gear ratio. Secondary pressure control valve 2
3 and the primary pressure regulating valve 24 are proportional solenoid valves, respectively, and the secondary pressure Ps and the primary pressure Pp are regulated by controlling the current values supplied from the shift control device 30 to the respective solenoid coils 23a, 24a. .

The torque converter 3 has a pump side shell 3a connected to the crankshaft 2 and a turbine runner 3b connected to the torque converter output shaft 19, and the torque converter output shaft 19 is fixed to the pump side shell 3a. A lock-up clutch 28 is attached to the front cover 27, which is pressed to transmit the engine torque. An apply chamber 28a is formed on one side of the lock-up clutch 28 to which a control hydraulic pressure for pressing and engaging the lock-up clutch 28 with the front cover 27 is formed, and on the other side, a release state for releasing the engaged state is formed. Chamber 28b
Are formed. By circulating the hydraulic pressure supplied to the release chamber 28b through the apply chamber 28a, the lockup clutch 28 is released and the torque converter 3 is activated. On the other hand, by adjusting the hydraulic pressure supplied to the release chamber 28b, the lockup clutch is in the half-clutch state, that is, the slip state.

The shift control device 30 includes a pulley rotation speed sensor 31 for detecting the rotation speed of the primary pulley 7, a vehicle speed sensor 32 for detecting the traveling speed of the vehicle, and a D selected by the driver operating a select lever. Range detection sensor 3 for detecting the driving range such as range and R range
3, a throttle sensor 34 for detecting the opening of a throttle valve of the engine 1, a brake switch 35 for detecting whether or not a brake pedal is operated, a lockup operating state detecting means 36 for detecting an operating state of the lockup clutch 28, Detection signals are sent from an engine speed sensor 37 that detects an engine speed, an ABS sensor 38 that detects a working state of an ABS (antilock brake system), and the like. ABS is a device for preventing wheel lock that occurs during sudden braking or braking on a slippery road surface such as a snowy road.

In order to detect the throttle opening, an accelerator sensor for detecting the opening of the accelerator pedal or an idling sensor for detecting that the engine is idling is used instead of the throttle sensor 34. You can In addition, the vehicle speed sensor 32
Alternatively, a sensor for detecting the rotation speed of the secondary pulley may be used to calculate the vehicle speed from the rotation speed.

This continuously variable transmission has an automatic transmission mode in which the transmission is automatically set according to the running state, and a manual mode in which the transmission ratio is set by manual operation. It is possible to switch between the automatic mode and the manual mode according to the user's selection.

The gear shift control device 30 uses the solenoid coils 23a, 24a based on the signals from the respective sensors.
It has a microprocessor that calculates a current value for a and a memory that stores a control program, a calculation formula, and map data.

In addition to the basic gear shift characteristic map for controlling the gear ratio, the engine speed, or the primary pulley speed based on a parameter indicating the operating condition such as the throttle opening, this continuously variable transmission allows the driver to operate the accelerator pedal. When the vehicle is traveling on a downhill road in a state of inertial traveling, that is, in a state of being released, a shift characteristic map for setting an inertial traveling mode for effecting engine braking is provided. In this variable speed running mode, the lower limit value of the target rotational speed is increased so as to increase the target rotational speed of the primary pulley in order to downshift the gear ratio.

Under the condition that the vehicle is running in the inertial driving mode, as described above, the lower limit value of the target speed is corrected so as to be increased. Under this condition, the accelerator pedal is depressed. Then, the lower limit value of the target rotational speed during inertial traveling is corrected based on the throttle opening and the vehicle speed without changing to the lower limit rotational speed in the basic shift characteristic map during normal traveling.

FIG. 2 is a shift characteristic diagram showing the lower limit value of the target rotational speed Np during inertial running with the lockup clutch 28 of the torque converter 3 engaged and disengaged. Although the effectiveness of the engine brake differs between when the lockup clutch 28 is engaged and when it is disengaged, when the lockup clutch 28 is disengaged, the target rotation speed Np is higher than when it is engaged.
Is set to a high rotational speed, the engine brake can be surely applied even when the lockup clutch 28 is released.

3A1 and 3A2 are shift characteristic diagrams showing the relationship between the vehicle speed V and the change rate lower limit value and change rate upper limit value when the lockup clutch 28 is engaged. 3 (B1) and 3 (B2) are shift characteristic diagrams showing the change rate lower limit value and the change rate upper limit value in the half-clutch state, respectively, and in FIGS. 3 (C1) and 3 (C2), the lockup clutch 28 is released. FIG. 9 is a shift characteristic diagram showing changes in the lower limit of change rate and the upper limit of change rate when the change is made.

As shown, the lockup clutch 2
In the half-clutch state where 8 is slipping, the controllability of the lock-up clutch 28 is maintained by not changing the rotation speed largely. Then, when the lock-up clutch 28 is released, the change rate is made larger than that when the lock-up clutch 28 is engaged, so that the speed is changed to the downshift side more quickly.

The map data corresponding to the gear shift characteristic diagrams shown in FIGS. 2 and 3 during inertial running is the gear shift control device 3.
0 is stored in the memory 0, and the respective shift characteristics are set by searching the map data according to the traveling state.

Next, the shift control in the transmission of the present invention will be described with reference to the flow chart.

FIG. 4 is a flow chart showing a main routine for setting the rotation speed and the gear ratio of the primary pulley, which is executed at every predetermined cycle. First, as is well known, the target primary rotation speed Np is set in step S1 by referring to the basic shift characteristic map based on parameters such as the accelerator opening and vehicle speed or engine rotation speed. Then, in step S2, the inertial running determination process is executed, in step S3, the upper limit value of the target rotation speed Np is set, in step S4 the lower limit value of the target rotation speed Np is set, and in step S5, the target rotation speed change amount The upper limit value is set, and the lower limit value of the target rotation speed change amount is set in step S6.

In step S7, an upper limit limiter process for the target revolution speed Np is executed, in step S8 a lower limit limiter process for the target revolution speed Np is executed, and in step S9 an upper limit limiter process for the target revolution speed change amount is executed.
In step S10, a lower limit limiter process for the target rotation speed change amount is executed. Then, steps S11 to S16
Is executed, and the optimum target rotation speed and gear ratio are set according to the running state of the vehicle.

FIG. 5 is a flowchart showing a subroutine of the inertial running determination processing in step S2 of FIG. 4. In step S21, it is determined whether or not the inertial running determination prohibition flag is set. If the inertial traveling determination prohibition flag is turned on, the inertial traveling determination flag is set to off in step S22. If the inertial traveling determination prohibition flag is turned off, the inertial traveling cancellation in step S23 and step S23 are performed.
The inertial traveling determination processing of 24 is executed.

[Inertial Running Mode Judgment Condition] The inertial running mode for applying the engine braking during traveling on a downhill is set when all of the following conditions are satisfied.
The conditions are as follows: first, the vehicle is traveling in a traveling range other than the parking range P, the neutral range N, and the reverse range R; second, the vehicle speed is within a predetermined range; That is, one of the conditions is continuously satisfied for a predetermined time or more. The three conditions are that the actual primary rotation speed Npi is larger than the engine rotation speed Ne when the lockup is released, the acceleration / deceleration is equal to or higher than a predetermined value, the accelerator pedal is released, and the engine rotation speed is idling. There is. When these conditions are satisfied, the inertia traveling mode is set.

FIG. 6 is a flowchart showing a subroutine for inertial running determination in FIG. 5. When it is determined in step S31 that the inertial running determination is not being performed, it is determined in step S32 whether or not the vehicle is in the running range D, and the step is executed. In S33, it is determined whether or not the vehicle speed is within a predetermined range, and in Step S34, it is determined whether or not the acceleration / deceleration determination 1 flag is turned on. These steps S3
If YES is determined in steps 2-34, step S35 is performed.
The inertial traveling determination flag is turned on. In step S31
When it is determined to be YES and N in steps S32 to S34
If it is judged to be O, the routine is exited as it is.

FIG. 7 is a subroutine for turning on / off the flag for acceleration / deceleration determination 1. In step S41, it is determined whether or not the inertial traveling is being determined.
In step S42, it is determined whether or not the lockup clutch 28 of the torque converter 3 is engaged. If not, the actual primary pulley rotation speed Npi is higher than the engine rotation speed Ne by a predetermined value Ns or more in step S43. Is judged. Further, in step S44, it is determined whether or not the acceleration / deceleration of the vehicle is larger than the predetermined value α, and in step S45, it is determined whether or not the accelerator is released.

In step S46, it is determined whether or not the timer T1 has passed the predetermined time Ta. If it is determined that the predetermined time has not passed, the unit time is increased in step S48 and the predetermined time passes. If it is determined that the acceleration / deceleration determination 1 is set, the flag for acceleration / deceleration determination 1 is turned on in step S47. On the other hand, when it is determined in step S41 that the inertial traveling determination is being performed, and in each of steps S43 to S43.
If NO is determined in 45, the timer T1 is reset in step S49, and the inertial traveling determination flag is turned off in step S50.

Therefore, by executing the routines of FIGS. 6 and 7, it is determined whether or not the inertia traveling mode described above is executed.

[Inertial traveling mode cancellation condition] The inertial traveling mode is canceled when any of the following conditions is satisfied. One of the conditions is a range other than the driving range D,
For example, parking range P, neutral range N
And the driver operates the select lever to one of the reverse range R and the reverse range R. The other one of the conditions is that the accelerator pedal has been depressed and the idling state has been turned off. If the inertial running mode is to be canceled under that condition, the target speed is reset to the original speed immediately after the cancellation. The change amount limiting process is not performed. Another one of the conditions is that the vehicle speed is outside the predetermined range. Further, another one of the conditions is that the following four conditions are continuously satisfied for a predetermined time or longer. The first condition is that the engine speed Ne is changed from the primary speed Np to the engine speed Ne during lockup release. When the subtracted value is larger than the predetermined value, the second condition is idling, the third is when the brake is released, and the fourth is when the acceleration / deceleration is less than the predetermined value. When all of the above conditions continue for a predetermined time, the inertial traveling mode is canceled.

FIG. 8 shows a subroutine for canceling the inertial running shown in step S23 of FIG. 5. In step S51, it is judged whether or not the above-mentioned flag indicating that the inertial running is being judged is turned on. If it is in the process of determination, it is determined in step S52 whether or not the traveling range is selected, in step S53 it is determined whether or not the vehicle speed is out of the predetermined range, and in step S54 whether or not the accelerator is depressed. In step S55, the target primary revolution speed Np is the inertia traveling primary revolution speed lower limit value Np.
Determine if it is greater than d.

NO in step S52, or step S52
When YES is determined in 53, step S61 is executed and the inertial traveling determination flag is turned off. Step S5
If NO in step 4 or NO in step S55, the timer T2 is reset in step S59. In step S56, the timer T2 sets the predetermined value Tb.
If it is equal to or more than the predetermined value, the limiter unnecessary flag is turned on in step S57 and the routine exits through step S61. If the predetermined time has not elapsed, the timer is set in step S58. T2
Is increased by a unit time, and it is determined in step S60 whether acceleration / deceleration determination 2 is turned on.

FIG. 9 is a flow chart showing a subroutine of acceleration / deceleration judgment 2. In step S71, it is judged whether or not inertia running is being judged, and in step S72 it is judged whether or not the lockup clutch 28 is in the engaged state. Judge,
If the lockup clutch 28 is not engaged, the value obtained by subtracting the engine speed Ne from the actual primary speed Npi is greater than or equal to the predetermined value Ns2 when the lockup clutch 28 is not engaged. In step S74, it is determined whether the acceleration / deceleration is equal to or less than a predetermined value, in step S75 it is determined whether the accelerator is released, and in step S76 it is determined whether the brake is released. To do.

When the above conditions are satisfied, step S7
If it is determined in step 7 that the timer T3 is equal to or greater than the predetermined value Tc, the acceleration / deceleration determination 2 is performed in step S78.
Flag is set to ON, and if it is not the predetermined value, the timer T3 is incremented by a unit time in step S79.
On the other hand, when the conditions in steps S71, S73 to S76 are not satisfied, the timer T3 is cleared in step S80, and the acceleration / deceleration determination 2 flag is set to OFF in step S81.

[Prohibition of Inertial Travel Judgment] The inertial travel mode is executed when the above-described conditions are satisfied. However, when there is a possibility of misjudging the inertial travel determination as described below, the inertial travel mode is executed. Is prohibited, and calculation of the lower limit of the rotational speed for inertial running is prohibited. As a result, it is possible to avoid the occurrence of unnecessary downshift due to a malfunction of the control, and it is possible to travel without feeling discomfort, and it is possible to improve the traveling performance of the vehicle.

FIG. 10 is a flow chart showing a subroutine for prohibiting the inertial running determination, and steps S91 and S9.
In step 2, it is determined whether or not the flags for the prohibition rapid deceleration determination and the prohibition rapid acceleration determination are respectively turned on. In step S93, it is determined whether the shift hold is in operation, and within a predetermined time after it becomes inoperative. Determine if there is,
In step S94, whether ABS is operating
It is determined whether or not S is inoperative within a predetermined time, and in step S95, it is determined whether or not the vehicle speed sensor 32 is out of order and whether or not the vehicle speed sensor 32 is OK within a predetermined time. In step S96, it is determined whether the manual mode is set and whether it is within a predetermined time after the manual mode is released. Step S
When YES is determined in any of steps 91 to S96, the inertial traveling determination prohibition flag is turned on in step S97, and in all of steps S91 to S96.
If NO is determined, the inertial traveling determination prohibition flag is turned off in step S98. Here, step S9
When the vehicle speed is detected by the secondary rotation speed sensor, the failure of the vehicle speed sensor 5 is detected as a failure of the secondary rotation speed sensor.

FIG. 11 is a flow chart showing a subroutine of the prohibition rapid deceleration determination. In step S101, it is determined whether or not the acceleration / deceleration is less than or equal to the determination acceleration / deceleration DECL. It is determined whether the determination time has passed. If the predetermined judgment time has elapsed, the prohibition rapid deceleration judgment flag is turned on in step S103, and the timer T5 is turned on in step S104.
To reset. On the other hand, if the predetermined determination time has not elapsed, the timer T4 is incremented by a unit time in step S105.

If NO in step S101, it is determined in step S106 whether the acceleration / deceleration is equal to or higher than the determination acceleration DECH.
Then, it is determined whether or not the timer T5 has passed the release time. If the predetermined release time has elapsed, step S10
In step 8, the prohibited rapid deceleration determination flag is turned off, and step S109
Reset the timer T4 with. On the other hand, if the predetermined release time has not elapsed, the timer T5 is set to step S111.
Increase the unit time with. If NO in step S106, the timer T5 is reset in step S110.

FIG. 12 is a flow chart showing a subroutine for prohibiting rapid acceleration determination. In step S121, it is determined whether or not the acceleration / deceleration is equal to or higher than a predetermined determination acceleration / deceleration INCH.
6 judges whether the judgment delay time has elapsed. If the predetermined judgment delay time has elapsed, step S1
In step 23, the prohibition rapid acceleration determination flag is turned on and step S12 is performed.
At 4, the timer T7 is reset. On the other hand, if the predetermined determination delay time has not elapsed, the timer T6 is incremented by a unit time in step S125.

If NO is determined in step S121, the acceleration / deceleration is determined by the predetermined determination acceleration / deceleration in step S126.
It is determined whether it is less than INCL, and if it is less than INCL, it is determined in step S127 whether the timer T7 has passed the release delay time. If the release delay time has elapsed, the prohibited rapid acceleration determination flag is turned off in step S128, and the timer T6 is reset in step S129.
On the other hand, if the predetermined release delay time has not elapsed, the timer T7 is incremented by a unit time in step S131. If NO is determined in the step S126, a step S
At 130, the timer T7 is reset.

[Setting of target lower limit value during inertial running] FIG. 13
4 is a flowchart showing a subroutine for setting a lower limit value of the target rotation speed Np shown in step S4 of FIG. 4, in which a target rotation speed lower limit value NPMINNORM for normal operation is calculated in step S141, and inertial running determination is prohibited in step S142. Determine whether or not. If not prohibited, step S1
In 43, it is determined whether or not the normal target rotation speed lower limit value NPMINNORM already set in step S141 is larger than the inertial traveling target rotation speed lower limit value Npd. Here, the normal target rotation speed lower limit value NPMINNORM is determined by the OD (overdrive) line or the minimum shift line of the vehicle speed line map. If YES is determined in this step S143, the target rotational speed lower limit value is set to the normal target rotational speed lower limit value NPMINNORM in a step S144. On the other hand, step S14
If NO is determined in 3, the target rotational speed lower limit value is set to the inertia traveling target lower limit value Npd in step S146. Also,
If it is determined in step S142 that the inertial traveling determination is prohibited, the target rotational speed lower limit value for inertial traveling is determined in step S145.
Set Npd and the lower limit value NPMINDAKOU0 during inertial running to the target lower limit value NPMINNORM for normal operation.

In this way, the lower limit value of the target rotational speed for inertial traveling of the primary pulley is set when the vehicle is inertially traveling on a downhill road and at a predetermined acceleration or deceleration of the vehicle. Thus, the engine braking force can be obtained.

As described above, when the accelerator pedal is depressed during inertial running, the lower limit value is corrected based on the throttle opening and the vehicle speed, so the accelerator is released again from the state where the accelerator is slightly depressed. Sometimes
The original required engine braking can be quickly obtained.

FIG. 14 shows the lower limit value NPMINDAKOU0 during inertial running.
Is a flow chart showing a subroutine of calculation, and if the flag for inertial running determination is turned on in step S151, it is determined in step S153 whether or not the lockup clutch is engaged. If the lock-up clutch 28 is engaged, the map shown in FIG. 2 when the lock-up clutch is engaged is searched in step S154 to calculate the lower limit value of the site, and if not engaged, step S155.
The lower limit value is calculated by searching the map shown in FIG. 2 when the lockup is released. When the flag for determination of inertial running is off, the inertial running lower limit NPMINDAKOU0 is set in step S152 by the normal target rotation speed lower limit NPMINNOR.

[Setting of rate of change] When the accelerator pedal is depressed during inertial running, the lower limit value of the target rotational speed for inertial running is based on the vehicle speed as shown in FIG. To correct. In this way, by applying the rotational speed change rate limit value determined by the vehicle speed, while preventing the rotational speed fluctuation when the inertial running control and this is released, without a sense of discomfort from low vehicle speed to high vehicle speed,
A feeling of hoop shift and down shift can be obtained.

FIG. 15 is a flowchart showing a subroutine for calculating the change amount limiter in steps S5 and S6 shown in FIG. 4. In step S161, it is determined whether or not the lockup clutch 28 is engaged, and the engagement is in progress. In this case, in step S162, it is determined whether the slip amount of the lockup clutch is within a predetermined range. When it is determined in step S162 that the lock-up clutch is in the engaged state, the change rate lower limit value during engagement is calculated in step S163 by searching the map data shown in FIG. 3 (A1), and in step S164. The change rate upper limit value at the time of engagement is calculated by searching the map data shown in FIG. 3 (A2). On the other hand, when the slip amount of the lockup clutch 28 is equal to or greater than the predetermined amount and the clutch is a half clutch, the process proceeds from step S162 to step S165, and the map data shown in FIG. 3B, the change rate upper limit value at the time of half clutch is calculated in step S166.
It is calculated by searching the map data shown in 2). Further, when it is determined in step S161 that the lockup clutch is opened, step S161
At 167, the lower limit of the change rate at the time of opening is calculated by searching the map data shown in FIG. 3 (C1), and step S1
At 68, the change rate upper limit value at the time of opening is calculated by searching the map data shown in FIG. 3 (C2).

FIG. 16 shows the lower limit value Npd during inertial running after setting the rate of change during inertial running by the rate of change limiter.
7 is a flowchart showing a calculation subroutine, in which it is determined in step S171 whether or not the limiter unnecessary flag is turned on. If it is determined that the limiter unnecessary flag is turned on, the limiter unnecessary flag is turned off in step S177, and in step S178. Lower limit value Npd during inertial running is set to NPMI
Set to NDAKOU0 and proceed to step S176. On the other hand, if it is determined in step S171 that the limiter unnecessary flag is off, the inertial traveling target rotation speed lower limit value Npd calculated in the previous routine in step S172.
That is, Npd-1 is the lower limit of the target inertial running speed NPMINDAKOU
It is determined whether or not it matches 0.

In step S173, it is determined whether or not the prohibition determination is turned on due to deceleration, and step S174
Then, it is determined whether or not the prohibition determination is turned on by convergence, and if the prohibition determination is turned off in these steps, the change amount limiter process 2 of step S175 is executed and the change rate limiting process of step S176 is performed. The prohibition flag is set. Also, step S172
When any one of the steps up to S174 is established, the routine exits through the above steps S178 and S176.

FIG. 17 is a flowchart showing a subroutine of the change amount limiter processing 2 shown in step S175 of FIG. 16. In step S181, it is determined whether or not the lower limit value Npd-1 of the previous target rotation speed is larger than NPMINDAKOU0. If it is YES in this step,
In step S182, the target rotational speed lower limit value Npd is set to Npd
It is set to a value obtained by adding the change rate lower limit value to n-1, and if NO is determined, Npd is set to a value obtained by adding the change rate upper limit value to Npdn-1 in step S185. N in step S183
It is determined whether pdn-1 is smaller than NPMINDAKOU0. If smaller, NPMINDAKOU0 is set to the target rotational speed lower limit value Npd for inertial running in step S184. Step S18
At 6, it is determined whether Npd is larger than NPMINDAKOU0. If it is larger, NPMINDAKOU0 is determined at step S187.
Is set to the target rotational speed lower limit value Npd for inertial traveling.

[Control During Sudden Deceleration] When a sudden deceleration is performed by stepping on the brake while the inertial traveling mode is being executed on a downhill road, the lower limit value of the target rotational speed for inertial traveling is set. The limit of the rate of change for setting is prohibited. As a result, when a sudden deceleration is performed, it is possible to quickly control the gear ratio and follow the target gear ratio. As a result, it is possible to prevent the engine speed from being kept high and excessive engine braking even when the vehicle is rapidly decelerated at a low vehicle speed. The prohibition of the change rate limitation is executed even when the lower limit value after the limiter converges to the lower limit value of the rotational speed before the change amount limiter.

FIG. 18 is a flow chart showing a subroutine of change rate restriction prohibition determination by deceleration. In step S191, it is determined whether or not the brake is depressed,
In step S192, it is determined whether the vehicle speed is less than or equal to a predetermined value, and in step S193, it is determined whether the acceleration / deceleration is less than or equal to the predetermined value A. If all of these conditions are satisfied and it is determined in step S194 that the timer T8 is equal to or greater than the predetermined value Td, the flag for the deceleration prohibition determination is turned on in step S195, and step S196 is performed.
Reset the timer T9 with. On the other hand, if it is determined that the value is equal to or less than the predetermined value Td, the timer T8 is increased in step S197.

If the acceleration / deceleration exceeds the predetermined value A in step S193, the flow advances to step S198 to determine whether the acceleration / deceleration is greater than or equal to the predetermined value B, and in step S199 whether the timer T9 is greater than or equal to the predetermined value Te. If each condition is satisfied, the flag for prohibition determination by deceleration is turned off in step S200, and the timer T8 is reset in step S201. On the other hand, if it is determined that the value is equal to or less than the predetermined value Te, the timer T9 is increased in step S202. If it is determined in step S198 that the acceleration / deceleration is less than or equal to the predetermined value B, the timer T9 is reset in step S203.

On the other hand, when the brake is depressed in step S191 or the vehicle speed exceeds the predetermined value in step S192, the above steps S200 and S are performed.
Exit the routine via 201.

FIG. 19 is a flowchart showing a subroutine for setting the change rate control processing prohibition flag by convergence. In step S210, it is determined whether Npd and NPDMINDAKOU0 match, and if it is determined that they match. Sets a determination prohibition flag due to convergence in step S211. In step S212, it is determined whether a change in the inertial running determination flag is detected, that is, whether the flag is switched from on to off or from on to off, and in step S213, the lockup clutch is switched from release to engagement. It is determined whether the connection has been made or the connection has been switched to the release. Step S21
If Npd and NPMINDAKOU0 do not match at 0, or if YES is determined in either of steps S212 and S213, step S214 is executed to turn off the inhibition determination by convergence.

The present invention is not limited to the above-mentioned embodiment, but various modifications can be made without departing from the scope of the invention.

For example, the target rotational speed and the inertial running rotational speed described above are the rotational speeds of the input side rotating body of the continuously variable transmission, that is, the primary pulley, but the respective rotational speeds may be the engine rotational speeds. In addition, in the shift control described above, the rotational speed for inertial traveling and the lower limit change rate are controlled.However, the rotational speed for inertial traveling is set as the gear ratio for inertial traveling, and the rotational speed lower limit value change rate for inertial traveling is set. The rate of change in the gear ratio for inertial traveling may be used. Further, although the continuously variable transmission shown in the drawing is a belt type transmission, it may be a toroidal type transmission.

[0069]

According to the present invention, in the shift control device for a continuously variable transmission according to the present invention, when the lockup clutch of the torque converter is engaged and released during inertial traveling on a downhill road. Since different lower limit values for inertial traveling are set depending on whether the torque converter is operated, an optimum engine braking force can be obtained regardless of the operation of the torque converter.

Further, when the lower limit value of the rotational speed for inertial traveling is switched in the lockup released state or the engaged state, the lower limit value is changed at a predetermined change rate in order to prevent the rotational speed from changing stepwise. Since the change rates are set to different values for the engagement and the release, it is possible to always obtain the optimum engine brake change regardless of the lockup state.

When the lockup clutch is slipping during the lockup engagement, another rate of change is set, so that the primary rotation speed is prevented from largely changing while the lockup clutch is slipping. Lock-up shock can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a drive system of a belt type continuously variable transmission which is an example of a continuously variable transmission.

FIG. 2 is a shift characteristic diagram showing a lower limit value of a target rotation speed during inertial running in a state where a lockup clutch of a torque converter is engaged and a state where the lockup clutch is released.

3 (A1) and (A2) are gear shift characteristic diagrams showing a relationship between a vehicle speed and a change rate lower limit value and a change rate upper limit value of a rotation speed when a lockup clutch is engaged,
(B1) and (B2) are shift characteristic diagrams showing the relationship between the vehicle speed and the change rate lower limit value and change rate upper limit value when the lockup clutch is a half clutch.
(C1) and (C2) are shift characteristic diagrams showing the relationship between the vehicle speed and the change rate lower limit value and change rate upper limit value of the rotational speed when the lockup clutch is released.

FIG. 4 is a flowchart showing a main routine of shift control.

FIG. 5 is a flowchart showing a subroutine of inertial running determination processing.

FIG. 6 is a flowchart showing a subroutine for inertial running determination.

FIG. 7 is a flowchart showing a subroutine of acceleration / deceleration determination 1.

FIG. 8 is a flowchart showing a subroutine for canceling inertial running.

FIG. 9 is a flowchart showing a subroutine of acceleration / deceleration determination 2.

FIG. 10 is a flowchart showing a subroutine for prohibiting inertial running determination.

FIG. 11 is a flowchart showing a subroutine of prohibition rapid deceleration determination.

FIG. 12 is a flowchart showing a subroutine of prohibition rapid acceleration determination.

FIG. 13 is a flowchart showing a subroutine for setting a target rotation speed lower limit value.

FIG. 14 is a flowchart showing a subroutine for calculating a lower limit value during inertial traveling.

FIG. 15 is a flowchart showing a subroutine of change amount limiter calculation.

FIG. 16 is a flowchart showing a subroutine for calculating a lower limit value during inertial traveling.

FIG. 17 is a flowchart showing a subroutine of change amount limiter processing 2.

FIG. 18 is a flowchart showing a subroutine of change rate restriction prohibition determination by deceleration.

FIG. 19 is a flowchart showing a subroutine for setting a change rate limiting process prohibition flag.

[Explanation of symbols]

1 engine 3 Torque converter 5 primary axis 6 Secondary axis 7 Primary pulley 8 secondary pulley 9 Belt (power transmission element) 21 oil pump 23 Secondary pressure control valve 24 Primary pressure control valve 30 speed change control device 31 Pulley rotation speed sensor 32 vehicle speed sensor 33 Range detection sensor 34 Throttle sensor 35 Brake sensor 36 Lockup clutch operating state detecting means 37 Engine speed sensor 38 ABS sensor

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3J552 MA07 MA12 MA26 NA01 NB01                       PA33 PA36 QA24 RB12 RB23                       RC07 RC12 SA31 SA34 SB02                       SB27 TB11 UA02 VA32W                       VA33W VA43W VB01W VC03W                       VE04W

Claims (4)

[Claims] 1. A continuously variable transmission in which the rotation of an input side rotating body driven by an engine via a torque converter equipped with a lockup clutch is continuously changed via a power transmission element and transmitted to an output side rotating body. A vehicle speed change control device, a vehicle speed detecting means for detecting a traveling speed of a vehicle, a throttle sensor for detecting an opening of a throttle, and an inertial traveling detecting means for detecting that the vehicle is inertially traveling on a downhill road. A clutch operating state detecting means for detecting an operating state of the lockup clutch; and a state in which the inertial traveling detecting means detects that the vehicle is inertially traveling on a downhill road. Lower limit value setting means for setting the target rotational speed lower limit value for inertial running, and lower limit value correcting means for correcting the lower limit value according to the operating state of the lockup clutch. A shift control device for a continuously variable transmission, comprising: 2. A continuously variable transmission in which the rotation of an input side rotating body driven by an engine via a torque converter equipped with a lockup clutch is continuously changed via a power transmission element and transmitted to an output side rotating body. A vehicle speed change control device, a vehicle speed detecting means for detecting a traveling speed of a vehicle, a throttle sensor for detecting an opening of a throttle, and an inertial traveling detecting means for detecting that the vehicle is inertially traveling on a downhill road. A clutch operating state detecting means for detecting an operating state of the lockup clutch; and a state in which the inertial traveling detecting means detects that the vehicle is inertially traveling on a downhill road. Lower limit value setting means for setting the target rotational speed lower limit value for inertial running, change rate limiting means for limiting the change rate of the lower limit value, and the operating state of the lockup clutch In response transmission controller for a continuously variable transmission system characterized by having a lower limit change rate correcting means for correcting the lower limit change rate. 3. The gearshift control device for a continuously variable transmission according to claim 1, wherein the inertial traveling target rotational speed lower limit value or the inertial traveling target rotational speed is respectively set when the lockup clutch is engaged, disengaged, and half-clutched. A shift control device for a continuously variable transmission, characterized in that the lower limit change rates are different. 4. The shift control device for a continuously variable transmission according to claim 1, wherein the inertia traveling speed lower limit value is a gear ratio lower limit value, and the lower limit change rate is a gear ratio. A shift control device for a continuously variable transmission, characterized in that a ratio of change ratio is used.