JP2878408B2 - Transmission control device for automatic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shift control device for an automatic transmission, and more particularly, to a shift control on a curved road (prior art). It tends to be used heavily. In this type of automatic transmission, gear shift control is generally performed based on an engine load and a drive system rotation speed. For this reason, the vehicle with an automatic transmission has a problem that an unnecessary shift is likely to be performed when traveling on a curved road. To explain this point in detail, when traveling on a curved road, braking is often performed immediately before the curved road to decelerate, as is called slow-in / first-out. Considering such a running state, the accelerator pedal is released immediately before the curved road, and the engine load is greatly reduced. Then, as the engine load decreases, the automatic transmission performs a shift operation. On the other hand, when the accelerator pedal is depressed immediately before exiting a curved road, the shift operation of the automatic transmission is performed as the engine load increases.

To cope with such a problem, Japanese Patent Application Laid-Open No. 63-177681 discloses a technique of restricting a shift operation when a vehicle is turning.

However, the turning state of the vehicle is various. For example, even when the vehicle starts to turn in a state where the high speed stage is selected and then brakes to decelerate, the automatic transmission is held at the high speed stage. Therefore, there is a problem that engine braking cannot be expected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a shift control device for an automatic transmission that can obtain an appropriate shift characteristic according to a turning state.

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration as a first configuration. That is, as described in claim 1 of the claims, a speed change gear mechanism capable of selectively achieving a plurality of power transmission paths, vehicle speed detecting means for detecting a value relating to vehicle speed, and detecting a value relating to engine load An engine load detecting means, a steering state detecting means for detecting a steering state, a shift characteristic preset based on a value related to a vehicle speed and a value related to an engine load, a detection result of the vehicle speed detecting means, Control means for controlling the transmission gear mechanism based on the detection result of the detection means and the detection result of the steering state detection means, wherein the control means controls the steering state at the beginning of turning of the vehicle when the vehicle turns. And the maximum vehicle angle at which the vehicle can turn is estimated based on the estimated maximum steering angle, and detected by the vehicle speed detection means. Vehicle speed to control the speed change gear mechanism as upshifting is limited when greater than the maximum vehicle speed that is the estimated, some such as configuration.

To achieve the above object, the present invention has the following configuration as a second configuration. That is, as described in claim 2 of the claims, a transmission gear mechanism capable of selectively achieving a plurality of power transmission paths, vehicle speed detecting means for detecting a value relating to vehicle speed, and detecting a value relating to engine load An engine load detecting means, a steering state detecting means for detecting a steering state, a shift characteristic preset based on a value related to a vehicle speed and a value related to an engine load, a detection result of the vehicle speed detecting means, Control means for controlling the transmission gear mechanism based on the detection result of the detection means and the detection result of the steering state detection means, wherein the control means controls the steering state at the beginning of turning of the vehicle when the vehicle turns. And the maximum steering angle is estimated from the estimated maximum steering angle, and the corner vehicle speed that can be taken in the corner deep portion is estimated based on the estimated maximum steering angle, and detected by the vehicle speed detection means. Actual vehicle speed to control the speed change gear mechanism so as to force a downshift when greater than corner speed which is the estimated, some such as configuration.

The estimation of the maximum vehicle speed or the estimation of the corner vehicle speed by the control means can be specifically performed as follows. That is, as described in claim 3 or claim 4 in the claims, the maximum steering angle is estimated based on the steering speed at the beginning of turning, and the radius of curvature of the road is estimated based on the estimated maximum steering angle. From the estimated radius of curvature, the maximum vehicle speed that can be obtained during turning or the corner vehicle speed at a deep corner can be estimated.

(Effect of the Invention) According to the first aspect of the invention, when the actual vehicle speed is higher than the estimated maximum vehicle speed at which the vehicle can turn, deceleration is required. Shifting is restricted to prevent a situation in which the engine brake is reduced due to upshifting, which is preferable in obtaining sufficient deceleration. In particular, since the predictive control for estimating the maximum vehicle speed based on the steering state at the beginning of turning is performed, sufficient deceleration can be obtained in advance.

According to the second aspect of the present invention, the fact that the actual vehicle speed is higher than the estimated corner vehicle speed is when deceleration is required, but in such a case, the downshift is forcibly performed. , You can get a big engine brake. In particular, since the predictive control for estimating the corner vehicle speed based on the steering state at the beginning of turning is performed, a sufficient engine brake can be obtained in advance.

According to the third and fourth aspects, a more specific method for estimating the maximum vehicle speed or the corner vehicle speed is provided.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

1 is an engine, and 2 is an automatic transmission. The output of the engine 1 is transmitted to drive wheels (not shown) via the automatic transmission 2.

The automatic transmission 2 includes a torque converter 3 and a planetary gear type multi-stage transmission mechanism 4. The torque converter 3 is provided with a lock-up clutch (not shown), and the lock-up solenoid 5 is switched between excitation and demagnetization so that lock-up is ON (fastened) and OFF (released). Further, the speed change mechanism 4 has four forward speeds in the embodiment, and the desired speed is set by changing the combination of excitation and demagnetization of the plurality of speed change solenoids 6 as is known. Of course, each of the solenoids 5 and 6 is for switching the operation mode of the hydraulic actuator for lock-up or shifting, but since these are well-known matters, further explanation will be omitted. Omitted.

In FIG. 1, reference numeral 10 denotes a control unit constituted by using a microcomputer, to which signals from respective sensors or switches 11 to 13 are inputted. The sensor 11 detects an accelerator depression amount, that is, an accelerator opening. The sensor 12 detects a vehicle speed. The sensor 13 detects the steering angle of the steering wheel. The control unit 10 outputs the signals to the solenoids 5 and 6.

The control unit 10 basically includes a CPU, a ROM, a RAM, a C
In addition to having a LOCK (soft timer), it also has an A / D or D / A converter and an input / output interface. However, since these are known configurations using a microcomputer, their description is omitted. The shift characteristics (map) used in the following description are stored in the ROM of the control unit 10.

As shown in FIG. 2, the shift characteristics are mapped using the accelerator pedal depression amount as the engine load and the vehicle speed as parameters, and when the driving state exceeds the shift-up characteristic line (the solid line in FIG. 2), the up-shift is performed. Is performed,
If the shift-down characteristic line (broken line in FIG. 2) is exceeded, a downshift is performed.

On the premise of the above, when the vehicle is turning, the control unit 10 performs control for changing the shift characteristics. To explain this point schematically, generally, there is a relationship as shown in FIG. 3 between the steering speed and the maximum steering angle. Therefore, by measuring the initial steering speed, the maximum steering angle on the curved road can be estimated. When the maximum steering angle is known, the radius of curvature of the curved road can be estimated based on the following equation.

R = (1 + AV ² ) · l / θ R: radius of curvature V: vehicle speed l: wheel base θ: maximum steering angle A: stability factor In this way, if the radius of curvature of a curved road is known, the following equation is obtained. It is possible to estimate the maximum vehicle speed that the vehicle can take at the time of turning.

Vmax: Maximum vehicle speed g: Gravitational acceleration f: Road surface friction coefficient i: Road surface gradient (bank) And comparing the maximum vehicle speed estimated in this way with the actual vehicle speed, the actual vehicle speed When the speed is higher than the maximum vehicle speed, it is determined that the control is likely to be performed thereafter, and the shift operation of the automatic transmission 4 is controlled.

An example of the above control will be described based on a flowchart shown in FIG.

First, in step S1, it is determined whether or not the control timing is reached. In S2, the vehicle speed, the steering angle θn, and the like are detected, and in the next S3, it is determined whether or not the flag F = 1. Here, the flag F indicates that the shift characteristic during turning is changed when F = 1, and normal shift control based on the map shown in FIG. 2 is performed when F = 0. Means that. At first, since F = 0, the process proceeds to S4, and the steering wheel θ
It is determined whether or not n has been cut to a predetermined value H or more. If YES, it is determined that the vehicle has started turning such that a change in the shift characteristics is required, and the process proceeds to step S5. The steering speed △ θ becomes the steering wheel angle θ
The maximum turnable vehicle speed Vmax is calculated based on the above-described method in the next step S6. And
In the next S7, the comparison between the maximum vehicle speed Vmax and the actual vehicle speed V is performed based on the following equation.

Vmax> kV Here, k: margin ratio When NO is determined in S7, that is, when the actual vehicle speed V is higher than the maximum vehicle speed Vmax, it is determined that the possibility that braking will be performed thereafter is large, and a flag is set in S8. The setting of F = 1 is performed.

Thus, when the process returns to the next S3, YES means that the process proceeds to S9, where it is determined whether or not the absolute value of the steering wheel steering angle θn is smaller than a predetermined value N. Since the vehicle is now turning, the determination is NO, and the process returns to S1 again. Then, when the turning is completed and the steering wheel is almost in a neutral state, the result is YES in S9, the flow proceeds to S10, the flag F is set to 0, and the next S11 is based on the map shown in FIG. Normal shift control is performed.

Therefore, when F = 1 is set in step S8,
The step S11 is jumped to stop the normal shift control based on the map, so that the shift stage before turning is maintained.

On the other hand, in the case of YES in S7, it is determined that the vehicle is not in a traveling state that impairs the stability of turning traveling of the vehicle.
Proceeding to S11, normal map control is performed. Therefore, when the accelerator pedal is released during the turn, as shown in FIG. 2, it is conceivable that the shift up from the point A to the fourth speed is caused by a change in the driving state from the point A. Since the vehicle has not been braked enough to require engine braking thereafter, the running stability of the vehicle is not impaired.

FIG. 5 shows a modification of the control shown in FIG. 4. In the following description, the same processing contents as those in FIG. 4 will be denoted by the same step numbers, and the description thereof will be omitted. Hereinafter, only the characteristic portions of this modified example will be described.

In this modification, the corner speed V _E at the deepest portion of the bent channel is calculated based on the following equation in S20.

t = θmax / Δθ where θmax: maximum steering angle obtained from FIG. 3 Δθ: steering speed t: time required to reach the deepest part of the curved road V _E = V−t · α V: actual vehicle speed α: deceleration of the vehicle and, in the next S21, comparison between the maximum vehicle Vmax and the corner predicted vehicle speed V _E is performed based on the following equation.

Vmax> kV _E Here, k: margin ratio When NO is determined in S21, the above-described S8
, A downshift from, for example, fourth speed to third speed is performed in S22.

That is, according to this modified example, since the actual vehicle speed compared with the maximum vehicle speed is compared with the corrected vehicle deceleration, the vehicle traveling state on the curved road is estimated with higher accuracy. . Then, the deceleration is large and when the predicted vehicle speed V _E is greater than the maximum vehicle speed Vmax, since as is when the engine brake is specifically required, one stage downshift is forced, can be provided to the hard travel Becomes

[Brief description of the drawings]

FIG. 1 is an overall system diagram of the embodiment, FIG. 2 is a map used for shift control of an automatic transmission, FIG. 3 is a diagram showing a relationship between a steering speed and a maximum steering angle during turning, and FIG. FIG. 5 is a flowchart illustrating an example of shift characteristic change control according to the embodiment. FIG. 5 is a flowchart illustrating details of shift characteristic change control according to a modification. 1: Engine 2: Automatic transmission 10: Control unit V: Actual vehicle speed θn: Steering angle Vmax: Maximum vehicle speed V _E : Corner vehicle speed (predicted vehicle speed in deep part)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48 B60K 41/00-41 / 28

Claims (4)

(57) [Claims] 1. A speed change gear mechanism capable of selectively achieving a plurality of power transmission paths, vehicle speed detecting means for detecting a value related to vehicle speed, engine load detecting means for detecting a value related to engine load, and detecting a steering state. A steering state detecting means, a shift characteristic preset based on a value related to a vehicle speed and a value related to an engine load, a detection result of the vehicle speed detecting means, a detection result of the engine load detecting means,
Control means for controlling the transmission gear mechanism based on the detection result of the steering state detection means, wherein the control means estimates the maximum steering angle from the steering state at the beginning of turning of the vehicle when the vehicle turns. At the same time, the maximum vehicle speed at which the vehicle can turn is estimated based on the estimated maximum steering angle. If the actual vehicle speed detected by the vehicle speed detection means is higher than the estimated maximum vehicle speed, the shift-up shift is limited. A shift control device for an automatic transmission, wherein the shift gear mechanism is controlled so as to be controlled. 2. A transmission gear mechanism capable of selectively achieving a plurality of power transmission paths, vehicle speed detecting means for detecting a value related to vehicle speed, engine load detecting means for detecting a value related to engine load, and detecting a steering state. A steering state detecting means, a shift characteristic preset based on a value related to a vehicle speed and a value related to an engine load, a detection result of the vehicle speed detecting means, a detection result of the engine load detecting means,
Control means for controlling the transmission gear mechanism based on the detection result of the steering state detection means, wherein the control means estimates the maximum steering angle from the steering state at the beginning of turning of the vehicle when the vehicle turns. At the same time, a corner vehicle speed that can be taken in a deep corner is estimated based on the estimated maximum steering angle, and when the actual vehicle speed detected by the vehicle speed detecting means is higher than the estimated corner vehicle speed, a downshift is forcibly performed. A shift control device for an automatic transmission, wherein the shift gear mechanism is controlled to perform the following. 3. The method according to claim 1, wherein the control means estimates a maximum steering angle based on a steering speed at an initial stage of turning, and estimates a radius of curvature of the road based on the estimated maximum steering angle. A shift control device for an automatic transmission, wherein a maximum vehicle speed that can be obtained when turning is estimated from the estimated radius of curvature. 4. The vehicle control system according to claim 2, wherein the control means estimates a maximum steering angle based on a steering speed at an initial stage of turning, and estimates a radius of curvature of the road based on the estimated maximum steering angle. A shift control device for an automatic transmission, wherein a corner vehicle speed that can be obtained at a deep corner is estimated from the estimated radius of curvature.