JPS6174945A - Control device of automatic speed change gear - Google Patents

Abstract

PURPOSE:To judge a failure in a car velocity sensor exhaustively by dividing a speed reduction decision level into zones according to the initial velocity and comparing the initial velocity with the present car velocity in every zone. CONSTITUTION:As the way of decreasing speed depends upon the car velocity just before decreasing, the speed reduction decision level alphan of a car velocity at the time of failure is previously divided into zones and memorized. A speed reduction decision level alphan corresponding to the initial velocity V0 among the speed reduction levels is found, and if a difference (V0-V) between the initial velocity V0 and the present car velocity V is larger than the speed reduction decision level alphan, it is judged that unusual speed reduction is performed. Thus, failure in all modes of a car velocity sensor can be judged by a car velocity signal of one system.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for an automatic transmission, and more particularly to a device for protecting an occupant and an automatic transmission when a vehicle speed sensor for detecting vehicle speed fails.

Background Art and Problems Therein Generally, in electronically controlled automatic transmissions, the gear ratio of the transmission gear is automatically controlled based on the throttle opening and vehicle speed. However, if the vehicle speed sensor that detects the vehicle speed malfunctions while driving or the wiring cable is disconnected, the vehicle speed signal becomes zero, resulting in the transmission being downshifted suddenly, causing the engine to rev up, or causing large gear changes. There is a problem with shock.

In order to solve such problems, the
As described in Publication No. 4, the engine rotation speed is detected,
There is a known system in which a shift amplifier is performed when this value becomes equal to or higher than the engine speed corresponding to a normal speed change, and a speed change operation similar to that when the vehicle speed sensor is operating normally is performed. By the way, if the vehicle speed signal line is disconnected, the vehicle speed signal will instantly become zero, so the above method can prevent sudden downshifts. In this case, the speedometer needle continues to rotate due to inertia, so it takes time for the vehicle speed signal to reach zero. When the vehicle speed signal gradually decreases in this way, it is almost indistinguishable from applying the brakes, so there is a risk that downshifts will be performed as the vehicle speed signal decreases, causing the same problems as before. .

On the other hand, there is also known a vehicle in which the vehicle speed signal is obtained from two systems: the speedometer and the output shaft of the transmission. In this case, even if one system breaks down, there will be no problem with driving as long as the other system is operating normally.However, since it is necessary to install two systems for the vehicle speed sensor and wiring cable, there is a disadvantage of high costs. be.

Purpose of the Invention The present invention has been made in view of such conventional problems.
The purpose is to provide a control device for an automatic transmission that can determine failures in all aspects of the vehicle speed sensor based on the vehicle speed signal of the I system and can safely control the automatic transmission.

Structure of the Invention In order to achieve the above object, the present invention calculates, when the vehicle speed signal decreases, the initial speed VO immediately before the decrease and the current vehicle speed ■ in the middle of decreasing, and also determines the deceleration determination level divided into a plurality of zones in advance. Among them, the deceleration determination level α corresponding to the above-mentioned initial speed VO. The difference between the initial speed VO and the current vehicle speed ■ is the deceleration judgment level α. When the value is higher than that, the failure determining means outputs an abnormality signal to maintain the current transmission gear position. That is, when the vehicle speed sensor fails and the vehicle speed signal decreases, the manner of decrease differs depending on how fast the vehicle was just before the decrease (initial speed Vo). Among these deceleration determination levels, the deceleration determination level αn corresponding to the above initial speed VO
The difference between the initial speed Vo and the current vehicle speed (Vo - V) is the deceleration determination level α. If it is larger than that, it means that the vehicle is decelerating in a way that would normally not occur (vehicle speed sensor is malfunctioning), so the current gear position is maintained to avoid sudden downshifts. It is something.

DESCRIPTION OF EMBODIMENTS FIG. 1 shows an example of a control device according to the present invention, where ① is a throttle opening sensor that detects the throttle opening, and 2 is a sensor that is installed on either the speedometer or the transmission output shaft to detect the vehicle speed. These sensors 1 and 2 are similar to those mounted on general automobiles.

Reference numeral 3 denotes a failure determination means, in which a vehicle speed signal is manually inputted from the vehicle speed sensor 2 at regular intervals, and when the vehicle speed signal from the vehicle speed sensor 2 suddenly decreases, the vehicle speed Vo immediately before starting deceleration is detected.
(referred to as initial speed) and the vehicle speed (referred to as current vehicle speed) during deceleration (referred to as current vehicle speed). The failure determination means 3 also includes a second
As shown in the figure, the rate of change in deceleration at the time of failure is stored in three zones, for example, depending on the initial speed, and a deceleration determination level αn (n=1 to 3) is set for each zone. That is, when Vo>Vl, the deceleration determination level is α8, ■; when >Vo>■2, the deceleration determination level is α2; when V2>Vo>V3, the deceleration determination level is α3. Then, the difference Vo between these deceleration determination levels α1 to α□ and the initial speed Vo and the current vehicle speed ■
-V, and if V o -V > α1 to α3, deceleration is being performed which is normally impossible (vehicle speed sensor 2
Therefore, the failure determining means 3 outputs an abnormal signal, and in the case of Vo-V<α1 to α3, outputs the current vehicle speed signal V as it is.

4 is a gear position determining means, which includes a throttle opening sensor 1;
A throttle opening signal from the controller and a signal from the failure determining means 3 are input. This transmission gear position determining means 4 uses the signal output from the failure determining means 3 as an abnormal signal (Vo-V>
When α1 to α, ), the current gear position is maintained regardless of the throttle opening signal, and if it is not an abnormal signal (Vo7V<α1 to α3),
A shift signal is output according to the vehicle speed and throttle opening according to a normal shift operation. The output signal from the transmission gear position determining means 4 operates the hydraulic circuit switching solenoid valve (shown in the figure) of the transmission via the shift output means 5. Third
This will be explained according to the flowchart in the figure. First, after starting, check the throttle opening and vehicle speed (V).

, V) are sequentially detected, and the initial velocity Vo and V□ are compared. V
If o<V, the initial speed is low, so no deceleration check is performed, and if Vo>V, the initial speed Vo is further compared with (2). In the case of Vo > V, the difference Vo -V between the initial speed Vo and the current vehicle speed V is compared with the deceleration determination level α1, and V
If o −V > α1, an abnormality is detected and V o −
'J < α1, deceleration check is not performed. Also,
In the case of Vo<V, the initial speed Vo and ■2 are further compared, and in the case of Vo>V2, the difference V between the initial speed Vo and the current vehicle speed ■
o -V and deceleration judgment level α2 are compared, and V o
If -V > α2, an abnormality is detected, and if Vo-V < α2, no deceleration check is performed. Furthermore, in the case of vO<■2, the difference V o -V between the initial speed Vo and the current vehicle speed V is compared with the deceleration determination level α3, and if Vo -V > α, an abnormality is detected and Vo - If V<α, no deceleration check is performed.

After detecting whether or not there is an abnormality as described above, if no abnormality is detected, the gear position is determined and the gear is shifted according to a normal speed change operation.

On the other hand, if an abnormality is detected, it means that the vehicle speed sensor 2 is malfunctioning, so a warning lamp or the like is flashed to warn the driver, and the malfunction determination means 3 outputs an abnormal signal to the gear position. A command is inputted to the determining means 4 to maintain (shift hold) the current transmission gear position. In other words, sudden downshifts are not performed, and engine revving and gear shift failure are prevented.

Note that if you stop the vehicle while maintaining the current gear position as described above, it will be difficult to start again, so release the shift hold and gradually downshift until the vehicle comes to a stop. It is necessary to control the For this purpose, for example, as shown in FIG. 1, the engine rotation speed N detected by the engine rotation speed sensor 6 is input to the failure determination means 3, and this engine rotation speed N is compared with a preset reference value Ns. By doing so, it can be determined whether the vehicle is traveling at high speed or not. That is, after carrying out a shift hold, the engine rotation speed N is detected as shown by the middle person in Figs. 3 and 4. When N>NS, the shift hold is continued because the vehicle speed is high, and when N<Ns, This means that the vehicle speed has become sufficiently low, so all you have to do is release the shift hold and downshift to first gear according to the normal gear shifting operation. The reference value Ns can be the engine speed during idling or the engine speed when the AT converter stalls.

Moreover, it is also possible to make a determination based on the intake pipe negative pressure of the engine instead of the above-mentioned rotational speed N.

That is, as shown in FIG. 1, the intake pipe negative pressure signal P from the engine intake pipe negative pressure sensor 7 is manually input to the failure determining means 3 and compared with a reference value Ps stored in the failure determining means 3 in advance. This reference value Ps can be, for example, the negative pressure in the intake pipe when the AT converter stalls. Then, in the case of P>Ps, shift hold is continued, and if P<Ps, shift hold is divided by IW.

In the above embodiment, failure determination was explained when the vehicle speed signal decreases over a certain period of time, such as when the speedometer cable is disconnected. Even in this case, the failure of the vehicle speed sensor can be determined in the same way as above. In other words, when the vehicle speed signal instantaneously becomes zero, the current vehicle speed V
Since V is zero, V o -V is naturally smaller than α□, and the current shift gear position can be maintained in the same order as above, thereby preventing shift shock and engine revving. Therefore, the present invention can deal with all kinds of failures of the vehicle speed sensor 2.

Effects of the Invention As is clear from the above explanation, according to the present invention, when the vehicle speed sensor fails while driving, the failure of the vehicle speed sensor is determined based on the manner in which the vehicle speed signal decreases, and a sudden downshift is prevented. , can prevent engine revving and shift shock. In particular, when a vehicle speed sensor fails, the way the vehicle speed signal decreases depends on the initial speed, so conventional methods could not distinguish between a vehicle speed sensor failure and sudden braking. Since the deceleration determination level is divided into zones depending on the magnitude of the initial speed, and the deceleration determination level is set for each zone and compared with the difference between the initial speed and the current vehicle speed, it is possible to determine the failure of the vehicle speed sensor without exception. Further, in the present invention, since a failure of the vehicle speed sensor is determined from the signal of the vehicle speed sensor of the 1 system, there is no need to install a separate sensor, and the configuration can be made in a simple manner.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a control device according to the present invention, FIG. 2 is a diagram showing a decreasing change in a vehicle speed signal when a vehicle speed sensor fails, and FIG. 3 is a flowchart diagram showing the operation of the device of the present invention.
FIG. 4 is a flowchart added to FIG. 1゛...Throttle opening sensor, 2...Vehicle speed sensor,
3...Failure determining means, 4...Transmission gear position determining means.

Claims (1)

[Claims] (1) In an automatic transmission that automatically controls the speed ratio of a transmission gear based on a throttle opening signal and a vehicle speed signal, when the vehicle speed signal decreases, the initial speed Vo immediately before the decrease and the current vehicle speed V in the middle of decrease are determined. At the same time, a deceleration determination level α_n corresponding to the initial speed Vo is determined from among the deceleration determination levels divided into a plurality of zones in advance, and when the difference between the initial speed Vo and the current vehicle speed V is higher than the deceleration determination level α_n, the failure determination means An automatic transmission control device that maintains the current gear position by outputting an abnormal signal.