JP3440692B2 - Transmission control device for continuously variable transmission - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for a continuously variable transmission, and more particularly to improvement of a shift control device having a manual mode.

[0002]

2. Description of the Related Art As a continuously variable transmission used in a vehicle,
Conventionally, belt type and toroidal type are known. In these shift control devices for continuously variable transmissions, a target input speed Ne * or a target gear ratio is set according to a vehicle speed VSP and a throttle opening TVO (or accelerator opening). i * is determined, and for example, there is one disclosed in Japanese Patent Laid-Open No. 1-303356.

This is because when the acceleration of the drive wheels exceeds a predetermined value, the target input rotational speed of the continuously variable transmission is reduced, that is, the gear ratio is changed to the Hi side and the drive wheels on a low μ road or the like are changed. It is intended to suppress slip.

[0004]

In the continuously variable transmission as described above, when kickdown acceleration is performed while traveling on a low μ road such as a snowy road, the input shaft speed of the continuously variable transmission is increased. In order to do so, the moment of inertia of the input shaft acts negatively to generate negative acceleration on the drive wheels, so the speeds of the drive wheels and the drive shaft are temporarily reduced, and the slip ratio of the drive wheels is the drive wheel speed. The vehicle body speed is equal to the vehicle speed VSP and is on the lock side. Then, when the increase in the input shaft speed of the continuously variable transmission is almost completed, the engine torque is amplified according to the gear ratio of the continuously variable transmission and then transmitted to the drive wheels, so that the acceleration of the drive wheels becomes negative. The slip ratio of the drive wheels turns positive, and the drive wheel speed is on the idling side in which the drive wheel speed is higher than the vehicle speed VSP.

However, in the above-described shift control device for a continuously variable transmission, on such a low μ road, the drive wheel speed is significantly lower than the vehicle speed at the initial stage of kickdown acceleration, and the downshift follows the drive wheel speed. Therefore, the gear ratio is changed to the Low side, which has a larger gear ratio than when the road surface μ is high.
Next, the driving wheel acceleration increases and the wheel slips, then upshifts, and the input shaft speed decreases at this time.
The inertial torque of the continuously variable transmission acts in the direction of accelerating the drive wheels, promoting the idling of the drive wheels, and reducing the drive torque and suppressing the slip of the drive wheels on the idling side. In some cases, smooth kickdown acceleration may not be possible on low μ roads.

Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a shift control device for a continuously variable transmission capable of quickly suppressing slippage of drive wheels during kickdown acceleration on a low μ road. To aim.

[0007]

As shown in FIG. 11, a first invention is a target gear ratio for calculating a target gear ratio i of a continuously variable transmission 100 according to at least a vehicle speed VSP and an accelerator pedal opening TVO. The calculation means 102 and this target gear ratio i *
In a shift control device for a continuously variable transmission, which comprises a shift control means 101 for controlling a gear ratio of the continuously variable transmission 100 in accordance with the above, a kick down detection for detecting a kick down based on an opening of the accelerator pedal is performed. Means 103, slip detecting means 104 for detecting that the drive wheels slip to the lock side, and the target gear ratio i when the slip detecting means 103 detects the slip of the drive wheels to the lock side during the kickdown. Second speed ratio control means 10 for reducing *
5 and 5.

A second aspect of the present invention is the slip detecting means 1 according to the first aspect of the invention, as shown in FIG.
Reference numeral 04 detects slip when the difference between the speed Nw of the driving wheel and the speed No of the driven wheel exceeds a predetermined value a.

As shown in FIG. 11, a third aspect of the invention is the slip detecting means 1 according to the first aspect of the invention.
Reference numeral 04 detects a slip when the acceleration α of the driving wheels is reduced to less than a predetermined acceleration b.

In a fourth aspect based on the first aspect, the second gear ratio control means 105 fixes the target gear ratio i * to a predetermined gear ratio on the upshift side.

Further, in a fifth aspect based on the fourth aspect, the predetermined gear ratio is set to an actual gear ratio when a slip of the drive wheels is detected.

In a sixth aspect based on the first aspect, the second gear ratio control means 105 upshifts to the minimum gear ratio HiRATIO in which the target gear ratio i * can be set.

[0013]

Therefore, according to the first aspect of the present invention, during normal traveling, the speed change of the continuously variable transmission is performed according to the target speed change ratio (or the target input speed) of the continuously variable transmission at least according to the vehicle speed VSP and the accelerator pedal opening. Although the ratio is controlled, when the driver depresses the accelerator pedal to start the kickdown, the downshift is performed according to the accelerator pedal opening. If the drive wheels slip to the lock side during this kickdown, the target gear ratio decreases and the gear shifts to an upshift, and the actual increase in input speed is suppressed early, so kickdown acceleration was performed on a low μ road. In this case, the drive wheel is once decelerated by the moment of inertia of the input shaft of the continuously variable transmission, slips to the lock side, and then tries to slip to the idling side according to the increased input rotation speed, but the target shift is made early. Since the ratio is upshifted, it is possible to quickly suppress idling of the drive wheels and smoothly perform kickdown acceleration on a low μ road.

In a second aspect of the invention, the slip is detected by determining a difference between a speed Nw of the driving wheel and a speed No of the driven wheel by a predetermined value a.
To detect the slip to the lock side when
The slip state can be detected quickly and easily.

As shown in FIG. 11, a third aspect of the present invention is based on the first aspect, wherein the slip detecting means reduces the slip detection so that the acceleration α of the driving wheel is less than a predetermined acceleration b. Since the slip is detected at this time, the kickdown acceleration on the low μ road can be smoothly performed even in the vehicle having no driven wheels.

According to a fourth aspect of the invention, the second target gear ratio control means fixes the target gear ratio i * to a predetermined gear ratio on the upshift side, so that the gear ratio during kickdown is fixed. With simple control, it is possible to quickly suppress the idling of the drive wheels and obtain the drive torque required for acceleration.

According to a fifth aspect of the present invention, the second target gear ratio control means fixes the target gear ratio i * to the actual gear ratio when the slip of the driving wheels is detected. It is possible to quickly suppress the idling of the drive wheels while obtaining the drive torque required for acceleration according to the target gear ratio corresponding to.

In the sixth aspect of the invention, the second target gear ratio control means upshifts to the minimum gear ratio HiRATIO in which the target gear ratio i * can be set, so that the torque transmitted to the drive wheels is suppressed. Thus, the idling of the drive wheels can be quickly suppressed.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example in which the continuously variable transmission 1 is composed of a toroidal type continuously variable transmission 10 that continuously changes the gear ratio in accordance with the tilt angles of the two power rollers 18, 20. The continuously variable transmission 1 includes a hydraulic control device 4 that controls a gear ratio i of the continuously variable transmission 10 in response to a command from the gear shift controller 2.

In the continuously variable transmission 10, a forward / reverse switching device 40 is provided between the engine and the torque converter 12, and the gear ratio i is changed by the hydraulic control device 4 supplied with hydraulic pressure from the hydraulic pump 84. Is to do. The torque converter 12 is provided as a starting element, and a lock-up (LU) clutch (not shown) is activated at a predetermined speed or higher to operate the engine and the continuously variable transmission 1.
The 0 input shaft is directly connected.

The hydraulic control device 4 of the continuously variable transmission 1 is provided with a step motor 61 driven by a shift control controller 2 mainly composed of a microcomputer, and the continuously variable transmission is provided in accordance with the driving amount of the step motor 61. The gear ratio i of 10, that is, the input shaft rotation speed Ne is changed.

The shift control controller 2 receives the engine speed Ne and the throttle opening TVO (or accelerator pedal opening) input from the engine controller 3,
The selector position of the shift lever 5 from the selector switch 5A and the input shaft rotation speed Nin and the output shaft rotation speed Nout (= vehicle speed) from the input shaft rotation sensor 6 and the output shaft rotation sensor 7 arranged in the continuously variable transmission 10. VSP) is read, and a target input rotation speed Ne * (= target speed ratio i *, the same applies hereinafter) is calculated according to the vehicle operating state, for example, the vehicle speed VSP and the throttle opening TVO. In the lockup state of the torque converter 12, that is, during normal running, the input shaft speed Nin from the input shaft rotation sensor 6 becomes equal to the engine speed Ne. Ne, the target value of the input shaft speed is the target input speed Ne *, and the target gear ratio i * is the target input speed Ne *.
And the output shaft speed Nout.

Further, the shift control controller 2 reads the driven wheel speed Nw and the driving wheel speed No from a driven wheel rotation sensor and a driving wheel rotation sensor (not shown), and calculates the driven wheel speed Nw as the vehicle speed VSP.

Then, the shift control controller 2 drives the step motor 61 of the hydraulic control device 4 based on the calculated target input speed Ne * to tilt the power rollers 18, 20 of the toroidal type continuously variable transmission 10. The turning angle is controlled so as to match the target gear ratio.

Here, the shift control controller 2 is shown in FIG.
As shown in FIG. 5, the RAM 50 serving as a storage unit for storing the shift map and the like is mainly composed of the CPU 50 that performs the arithmetic processing.
1. An A / D converter 53 having a ROM 52 and further reading a throttle opening TVO from the engine control controller 3, an engine speed Ne from the engine controller 3 and a rotation speed of an input / output shaft of the continuously variable transmission 10. A counter 54 for inputting Nin and Nout, a driven wheel speed rotation sensor, a driven wheel speed Nw from the driving wheel speed rotation sensor, a driving wheel speed No and a digital I / O 55 for reading a signal from a selector switch of the shift lever 5, and a hydraulic pressure. Digital I / O 56 for driving the step motor 61 of the controller 4
Composed of.

Next, an example of the control performed by the shift control controller 2 is shown in the flow charts of FIGS. 3 to 5, and will be described in detail with reference to these flow charts. Note that each flowchart is executed every predetermined time, for example, every 10 msec. FIG. 3 is a main routine of shift control, FIG. 4 is a subroutine for searching for the target input rotation speed Ne *, and FIG. Subroutines for setting the target input rotation speed Ne * at the time are shown respectively.

In step S1 of FIG. 3, the operating state of the vehicle is detected by reading the data from the various sensors. The engine speed Ne and the throttle opening TVO are read from the engine controller 3 and the continuously variable transmission is also used. Input shaft rotation speed Nin = actual input rotation speed Ne and output shaft rotation speed Nout are read from 1, and drive wheel speed No,
Read the driven wheel speed Nw.

Then, in step S2, the driven wheel speed Nw is
And the drive wheel speed No, the slip ratio sl of the drive wheels is calculated by the following equation.

Sl = (Nw-No) / Nw This slip ratio sl indicates a slip to the lock side when it is positive and a slip to the idling side when it is negative.

Next, at step S3, it is determined whether or not kickdown is in progress based on a signal from a throttle opening TVO (accelerator pedal opening) or a kickdown switch (not shown). On the other hand, if it is determined that the kickdown has not occurred while proceeding to step S4, the process proceeds to step S9 to reset the flag Fc, and then proceeds to step S6 to search and set the target input rotation speed Ne *.

In step S4, it is determined whether or not the flag Fc is in the set state, that is, whether or not the kickdown control is being performed. If the flag Fc has already been set, the process directly proceeds to step S10, While maintaining the current target input rotation speed Ne * as it is, immediately after the start of kickdown in which the flag Fc is not set, the process proceeds to step S5.

In step S5, the slip ratio sl determined in step S2 is compared with a predetermined value a to detect a slip state to the lock side where the slip ratio sl is larger than the predetermined value a. Then, this slip ratio sl is a predetermined value a
If the slip to the lock side exceeds the limit, step S
While proceeding to 7 and S8 to start the kick-down control, if not so, proceeding to step S6 to perform normal shift control.

As shown in FIG. 4, the normal shift control performed in step S6 is to search the target input speed Ne * from the shift map corresponding to the vehicle speed VSP and throttle opening TVO read in step S1. In this shift map, as shown in FIG. 6, the target input speed Ne * corresponding to the throttle opening TVO and the vehicle speed VSP, that is, the target gear ratio, is set between the highest Low line and the highest High line. .

On the other hand, the kickdown control in which the slip ratio sl to the lock side exceeds the predetermined value a is started from step S7, and the target input rotation speed N at the time of slip is N in step S7.
After setting e * as described later, in step S8, a flag Fc indicating that the kickdown control is in progress is set and then in step S8.
Go to 10.

Here, the target input rotational speed Ne * of the kick-down control performed in step S7 is determined by step S2 in FIG.
As shown in 0, the current actual input speed Ne is set as the target input speed Ne *.

Then, in step S10, the actuator such as the step motor 61 is driven so that the actual input speed Ne of the continuously variable transmission 10 matches the target input speed Ne *.

When the driver depresses the accelerator pedal to perform kickdown acceleration by repeating the control of steps S1 to S10, and the slip ratio sl of the drive wheels to the lock side exceeds the predetermined value a. , The target input speed Ne * is changed from the value of the shift map to the current actual input speed Ne, and the target input speed Ne during kickdown
* Is fixed to this actual input speed Ne.

That is, as shown in FIG. 7, when kickdown is started at time t1 while traveling on a low μ road such as a snowy road, first, the target input speed Ne * is changed to the shift map of FIG. On the basis of this, downshift is performed up to a predetermined rotation speed.

From the time t2, the throttle opening T
The increase of the engine speed Ne according to VO and the increase of the actual input speed Ne of the continuously variable transmission 10 start with the increase of the gear ratio. However, as described above, at this time, the moment of inertia of the input shaft of the continuously variable transmission 10 negatively acts to generate negative acceleration on the drive wheels, so that the drive wheel speed No on the low μ road is after time t2. Then, the vehicle speed is decelerated once, and the slip ratio sl of the drive wheels is on the lock side where the drive wheel speed No is smaller than the vehicle body speed = the driven wheel speed Nw.

Here, at time t3 when the slip ratio sl exceeds the predetermined value a, the process proceeds from the determination at steps S3 to S5 to step S7, kick down control is started, and the target input rotation speed Ne * is time t3. Is fixed to the actual input rotation speed Ne. At this time, since the actual input speed Ne has not reached the target input speed Ne * before the time t3, the target input speed Ne * is upshifted to the actual input speed Ne at the time t3 as shown by the solid line in the figure. It will be fixed at this value until the kickdown ends.

Therefore, the actual input speed Ne increased from the time t2 reaches and is maintained at the actual input speed Ne at the start of the kick-down control as shown by the solid line in the figure after the time t4. From positive to negative, that is, after the time t5 when the lock side is reversed to the idling side, an increase in the slip ratio sl (increase in idling) is quickly suppressed, and a predetermined slip ratio sl is maintained to accelerate the vehicle. Since the driven wheel speed Nw can be smoothly increased, the kickdown acceleration on the low μ road can be smoothly performed, and the drivability of the vehicle including the continuously variable transmission can be improved. is there.

On the other hand, in the above-mentioned conventional example, as shown by the broken line in the figure, the time t5 in which the acceleration of the drive wheels exceeds the predetermined value
For the first time, the target input speed Ne * is suppressed, and at this time, since the actual input speed is significantly higher than that of the present invention, the slip ratio of the drive wheels to the idling side is also increased.
It takes time up to time t6 until the slip ratio converges.

Therefore, in the present invention, when slippage of the drive wheel to the lock side is detected during kickdown acceleration, the drive wheel is upshifted earlier than in the prior art to maintain this target input speed. The time required for the slip ratio sl to converge can be shortened according to the difference between the times t6 and t5, and the kickdown acceleration on the low μ road can be smoothly performed.

Although the target input speed Ne * during the kickdown control is the actual input speed Ne at the time t3, it may be a predetermined value on the upshift side.

FIG. 8 shows the second embodiment, and the conditions for starting the kickdown control in steps S2 and S5 shown in FIG. 3 of the first embodiment are as follows. To step S2 ', S respectively
5 ', and other points are the same as those in the first embodiment.

In step S2 ', the last drive wheel speed No.
The driving wheel acceleration α is calculated from the difference between old and the current driving wheel speed No. In step S5 ′, when the driving wheel acceleration α is less than the predetermined value b, kick down control is performed from step S7. Then, the predetermined value b is set to a negative acceleration in which the slip ratio sl is on the lock side, and the same operation and effect as in the first embodiment can be obtained.

Therefore, as shown in FIG. 9, time t3
When the driving wheel acceleration α is less than the predetermined value b and the locking tendency is detected, the target input rotation speed Ne * is fixed to the actual input rotation speed Ne at that time, and the same as in the first embodiment, the conventional example. By performing the upshift earlier than the above, it is possible to secure the drive torque necessary for acceleration while suppressing the idling of the drive wheels, and perform smooth acceleration.

FIG. 10 shows the third embodiment, and the setting of the target input speed Ne * in step S20 performed in step S7 of the first or second embodiment is set in step S20 '.
Others are the same as those in the first or second embodiment.

In step S20 ', the target input rotational speed Ne * during kickdown control is set to a value obtained by multiplying the driving wheel speed No at that time by the minimum gear ratio HiRATIO. This minimum gear ratio HiRATIO is In the shift map of No. 6, the slope of the highest Hi line is shown, which is the minimum gear ratio that can be set by the continuously variable transmission 10.

In this case, when the drive wheels slip to the lock side during kickdown acceleration, the target input speed Ne * based on the drive wheel speed No and the minimum gear ratio HiRATIO at that time is upshifted. The torque transmitted to the drive wheels can be reliably suppressed, and the idle rotation of the drive wheels can be quickly suppressed.

In the above embodiment, an example in which the continuously variable transmission 10 is of a toroidal type is shown, but it may be of a belt type or the like although not shown.

[0053]

As described above, according to the first aspect of the present invention, if the driving wheel slips to the lock side during the kick down when the driver depresses the accelerator pedal, the target gear ratio is reduced and an upshift is performed. Since the increase in input speed is suppressed early, when kickdown acceleration is performed on a low μ road, the drive wheels are temporarily decelerated due to the moment of inertia of the input shaft of the continuously variable transmission and slip to the lock side. After that, it tries to slip to the idling side according to the increased input speed, but because the target gear ratio is upshifted early, the idling of the drive wheels is quickly suppressed to accelerate the kickdown on low μ roads. And the drivability of the vehicle equipped with the continuously variable transmission can be improved, and in particular, the time until the idle rotation of the drive wheels converges can be shortened as compared with the conventional example. Is possible It

In the second aspect of the invention, the slip is detected by detecting a difference between the speed Nw of the driving wheel and the speed No of the driven wheel by a predetermined value a.
To detect the slip to the lock side when
The slip condition can be detected quickly and easily.
With simple control, kickdown on a low μ road can be performed smoothly.

In the third aspect of the invention, the slip detecting means detects the slip when the acceleration α of the driving wheel decreases below a predetermined acceleration b. Even in a vehicle such as an all-wheel-drive vehicle that does not have it, kickdown acceleration can be smoothly performed on a low μ road, and the applicable vehicle can be expanded.

In the fourth aspect of the invention, the second target gear ratio control means fixes the target gear ratio i * to a predetermined gear ratio on the upshift side, so that the gear ratio is fixed during kickdown. With simple control, the drive torque required for acceleration can be obtained while quickly suppressing the idling of the drive wheels, and the drivability of the vehicle equipped with the continuously variable transmission can be improved.

Further, in the fifth aspect of the invention, the second target gear ratio control means fixes the target gear ratio i * to the actual gear ratio when the slip of the driving wheels is detected. It is possible to quickly suppress the idling of the drive wheels while obtaining the drive torque required for acceleration according to the target gear ratio according to
It is possible to improve the drivability of the vehicle including the continuously variable transmission.

In the sixth aspect of the invention, the second target gear ratio control means upshifts to the minimum gear ratio HiRATIO in which the target gear ratio i * can be set, so that the torque transmitted to the drive wheels is suppressed. Thus, the idling of the drive wheels can be quickly suppressed, and the drivability of the vehicle equipped with the continuously variable transmission can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a continuously variable transmission showing an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a shift control controller.

FIG. 3 is a flowchart showing an example of control performed by a shift control controller, showing a main routine.

FIG. 4 is a flowchart of a subroutine similarly showing an example of normal shift control.

[Fig. 5] Similarly, target input speed N during kickdown control
The flowchart of the subroutine which shows an example of e * setting.

FIG. 6 is a shift map of the target input speed Ne * according to the vehicle speed VSP with the throttle opening TVO as a parameter.

FIG. 7 is a graph showing the relationship between target input speed Ne *, actual target input speed (engine speed Ne), drive wheel speed, driven wheel speed, slip ratio, and time in an explanatory view showing the operation.

FIG. 8 is a flowchart of a main routine according to the second embodiment.

FIG. 9 is an explanatory view showing the same operation, in which the target input speed N
The graph which shows the relationship of e *, real target input speed (engine speed Ne), drive wheel acceleration (alpha), and a slip ratio, and time.

FIG. 10 is a flowchart of a subroutine according to the third embodiment and showing an example of target input speed Ne * setting during kickdown control.

FIG. 11 is a claim correspondence diagram corresponding to any one of the first to sixth inventions.

[Explanation of symbols]

2 Shift control controller 6 Input shaft rotation sensor 7 Output shaft rotation sensor 10 continuously variable transmission 61 step motor 100 continuously variable transmission 101 shift control means 102 target speed ratio calculating means 103 Kickdown detection means 104 Slip detection means 105 Second gear ratio control means

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (6)

(57) [Claims] 1. A target gear ratio calculating means for calculating a target gear ratio of a continuously variable transmission according to at least a vehicle speed and an accelerator pedal opening, and a gear ratio of the continuously variable transmission controlled according to the target gear ratio. A shift control device for a continuously variable transmission, comprising: a shift-down control unit for detecting a kick-down based on an opening degree of the accelerator pedal; and detecting that a driving wheel slips to a lock side. And a second gear ratio control means for decreasing the target gear ratio when the slip detecting means detects a slip of the driving wheels toward the lock side during the kickdown. Shift control device for continuously variable transmission. 2. The continuously variable transmission according to claim 1, wherein the slip detecting means detects a slip when a difference between the speed of the driving wheel and the speed of the driven wheel exceeds a predetermined value. Shift control device. 3. The shift control device for a continuously variable transmission according to claim 1, wherein the slip detecting means detects a slip when the acceleration of the driving wheels is reduced to less than a predetermined acceleration. 4. The gear shift control device for a continuously variable transmission according to claim 1, wherein the second gear ratio control means fixes the target gear ratio i to a predetermined gear ratio on the upshift side. . 5. The gear shift control device for a continuously variable transmission according to claim 4, wherein the predetermined gear ratio is set to an actual gear ratio when a slip of a drive wheel is detected. 6. The shift control device for a continuously variable transmission according to claim 1, wherein the second gear ratio control means upshifts the target gear ratio to a settable minimum gear ratio.