JP2666474B2 - Fail-safe control device for automatic transmission - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fail-safe control device for an automatic transmission, and more particularly, to a fail-safe control device that prohibits an abnormality determination process of a turbine sensor in a vehicle coast state.

2. Description of the Related Art Recent automatic transmissions for vehicles are disclosed in, for example, Japanese Patent Application Laid-Open No. 62-62047.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-207, there is a type in which shift control is performed by electronic control. By performing such electronic control, it is possible to reduce shift shock and shift in a more ideal state. Is available.

When the shift control is to be performed by electronic control in this manner, vehicle running conditions such as a vehicle speed and an engine speed are input to an A / T control unit, and various types of gears for performing a shift by the A / T control unit are input. A control signal is calculated.

In the automatic transmission, the engine power is normally input via a torque converter, and the turbine rotation on the output side of the torque converter (this turbine rotation is the input rotation of the automatic transmission). Is constantly detected by the turbine sensor, and one of the vehicle running conditions
Used as one.

By the way, in the automatic transmission based on the electronic control, when various sensors for performing the shift control fail, an appropriate shift cannot be performed. Therefore, the self-diagnosis of the various sensors is performed to perform a fail-safe measure. It has become.

For example, the turbine sensor uses a vehicle speed signal,
When the turbine speed detected by the turbine sensor is low at a speed equal to or higher than a predetermined vehicle speed, it is considered that the turbine sensor is determined to be abnormal. Is higher than or equal to a predetermined rotation speed and the turbine rotation speed is low, it is considered that the turbine sensor is determined to be abnormal.

However, when an attempt is made to determine a turbine sensor abnormality based on a vehicle speed signal, there is a case where the turbine rotation is exceptionally reduced due to the operation of the one-way clutch of the transmission while the coasting is being performed even at a predetermined vehicle speed or higher. is there.

Therefore, the abnormality determining means for determining the abnormality of the turbine sensor includes an ON / OFF signal (ON
The idle state is input, and when ON, it is determined that coasting is running, and the abnormality determination processing is stopped.

The idle switch is provided in a throttle valve, and ON / OFF is determined by opening and closing the throttle valve.

Problems to be Solved by the Invention However, in recent engines, when the cooling water temperature is low, the throttle valve is automatically opened to increase the idling speed, so even though the accelerator pedal is not depressed. Then, the idle switch is turned off.

For this reason, since the abnormality determination processing of the turbine sensor is executed by turning off the idle switch, there is a problem that the turbine sensor is determined to be abnormal regardless of the coasting state.

Accordingly, the present invention has been made in view of the above-described conventional problems, and enables an abnormality determination process in a coasting state to be reliably stopped so that the coasting state can always be accurately detected regardless of the cooling water temperature of the engine. An object of the present invention is to provide a fail-safe control device for an automatic transmission that can reliably eliminate erroneous abnormality determination of an input rotation sensor.

Means for Solving the Problems In order to achieve this object, the present invention is, as shown in FIG. 1, connected to an engine that automatically opens a predetermined amount of a throttle valve when a cooling water temperature is low. Used in an automatic transmission in which power transmission from the output side to the input side is interrupted, the automatic transmission including abnormality determination means for determining abnormality of the transmission input rotation sensor using the transmission output shaft rotation speed. In a fail-safe control device for a transmission, an output of a variable resistor provided in a throttle valve is used to determine that the throttle valve opening is equal to or less than a reference value set to a value equal to or more than the predetermined amount that opens when the cooling water temperature is low. A soft idle signal detecting means for detecting a signal based on the value and outputting a signal to the abnormality determining means; and providing a signal when the soft idle signal detecting means outputs the signal. The abnormality determination means is configured to stop the abnormality determination processing.

In the automatic transmission fail-safe control apparatus according to the present invention, the soft idle signal detecting means c
Thus, a substantial idle state can be detected. Therefore, when a signal is output from the detection means, it is determined that the transmission function is a coasting function, and the abnormality determination processing of the transmission input rotation sensor a is stopped. The abnormality determination of the sensor a can be accurately performed.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 shows a first embodiment of the fail-safe control apparatus for an automatic transmission according to the present invention, in which 10 is an engine, and 12 is an automatic transmission.

In the engine 10, the amount of air introduced into the engine 10 is adjusted according to the opening degree of a throttle valve 16 provided in the throttle chamber 14, and the air-fuel mixture is controlled according to the amount of intake air.

On the other hand, the automatic transmission 12 is connected to the engine 10 and receives the engine rotation via a torque converter (not shown) .Shift control of the automatic transmission 12 is performed by a control valve 18. This is performed by appropriately engaging or releasing the friction element by the output control hydraulic pressure. By the way, the control valve 18 is various signals output from the A / T control unit 20, for example,
As disclosed in Japanese Patent Application Laid-Open No. 62-62047, the control hydraulic pressure is controlled by a line pressure control signal, a shift valve switching signal, and the like.

The various signals output from the A / T control unit 20 are based on vehicle traveling conditions input to the A / T control unit 20, for example, a vehicle speed signal, a throttle opening signal, a hydraulic oil temperature signal, and the like. It is determined.

Further, the A / T control unit 20 also has a function as a fail-safe control device, and an abnormality determining means 22 is provided in the A / T control unit 20.

The abnormality determining means 22 receives an idle signal based on ON / OFF from an idle switch 24 provided in the throttle chamber 14, and receives a turbine rotation signal from a turbine sensor 26 which detects transmission input rotation.

When the idle switch 24 outputs an OFF signal (other than the idle state), the abnormality determination means 22 executes abnormality determination processing, and executes the turbine sensor.
When the rotation speed signal output from 26 deviates from a predetermined rotation speed region, it is determined that the turbine sensor 26 is abnormal.

The abnormality determination signal is output to the control valve 18 of the automatic transmission 12 via the A / T control unit 20, and, for example, line pressure control or shift control is performed.

Here, in the present embodiment, a variable resistor 32 whose electric resistance changes in accordance with the throttle valve opening is provided on the throttle valve 16 operated by the accelerator pedal 28, and the variable resistor 32 is It is used as idle detection means. Accordingly, the variable resistor 32 can detect the opening of the throttle valve 16 in a stepless manner, and when the opening of the throttle valve 16 is 1/8 or less, this is set as a soft idle signal ON. The information is output to the abnormality determining means 22. In this embodiment, the 1/8 opening of the throttle valve 16 serves as a reference value, and this reference value is set to be equal to or greater than the opening of the throttle valve 16 which is automatically opened when the engine coolant temperature is low.

When the idle switch 24 outputs an OFF signal (a signal other than the idle state), the abnormality determining means 22 determines an abnormality using the soft idle signal.

That is, the abnormality determining means 22 is controlled according to the flowchart shown in FIG. 3. First, at step I, it is determined whether or not the idle switch 24 is ON.
In this case, the routine proceeds to step II, where the failure (abnormal) judgment of the turbine sensor 26 is prohibited, and the abnormality judging process is stopped.

On the other hand, if “NO” is determined in step I,
Proceeding to step III, it is determined whether the soft idle signal is ON.If "YES", the process proceeds to step II and the abnormality determination process is stopped.If "NO", the process proceeds to step IV and the turbine sensor By permitting 26 fail judgments, the abnormality judgment processing is executed.

With the above-described configuration, in the fail-safe control device for the automatic transmission according to the present embodiment, the cooling water temperature is increased after the engine 10 is warmed up.
The opening and closing of the throttle 16 is changed in accordance with the amount of depression of the accelerator pedal 18. In an idle state where the foot is released from the accelerator pedal 28, the throttle chamber 14 is closed and an ON signal is output from the idle switch 24.

On the other hand, when the cooling water temperature is low, the throttle chamber 14 is opened even in the idle state, and the OFF signal is output from the idle switch 24. Therefore, the abnormality determination process is stopped only with the detected value of the idle switch 24. In this case, since the throttle valve 16 has an opening smaller than the reference value, the soft idle signal is turned on, and the abnormality determination process can be stopped by turning on the soft idle signal.

Therefore, even immediately after the start of the engine 10 at a low temperature, the abnormality of the turbine sensor 26 can be determined, and safety can be further ensured.

 Next, FIG. 4 shows a flowchart of the second processing example.

In this embodiment, a step V for judging the engine cooling water temperature and a step VII for judging the idling state by soft idling are added to the first processing example, and the idle switch 24 is turned off, that is, when the step I is "NO". If it is determined, the engine cooling water temperature is determined in step V, and if it is equal to or higher than a predetermined value, “YES” is determined, and step V
The throttle opening is determined in II, if not greater determination than theta _0, soft idle signal prohibits the fail determination of the ON and the turbine sensor.

Then, when the engine coolant temperature is below a predetermined value in step V is determined as "NO", it is determined throttle opening in step III, the soft idle signal if not greater determination than the predetermined value θ _{0 +} θ ₁ Turns on, prohibiting turbine sensor failure judgment.

Therefore, even when the idle switch has failed in step VII, it is possible to make an accurate turbine sensor fail determination.

In the above embodiment, the idle switch and the soft idle are used together. However, in the present invention, the control may be performed using only the soft idle.

Effect of the Invention As described above, in the fail-safe control device for an automatic transmission according to the present invention, the reference value is set such that the throttle valve opening is set to a value that is equal to or greater than an amount that automatically opens when the cooling water temperature is low. The following is provided based on the output value of the variable resistor provided in the throttle valve, provided with a soft idle signal detection means for outputting a signal to the abnormality determination means,
When the soft idling signal detecting means outputs a signal, the abnormality judging means stops the abnormality judging process. Therefore, the substantial idle taking into account the throttle valve opening automatically adjusted when the cooling water temperature is low. It is possible to detect the state, and as a result, there is an excellent effect that the abnormality determination of the transmission input rotation sensor can be accurately performed irrespective of a decrease in the cooling water temperature of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram showing the concept of the present invention, FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention, and FIG. Flowchart showing a first processing example, fourth flowchart
FIG. 11 is a flowchart illustrating a second processing example. 10 ... engine, 12 ... automatic transmission, 14 ... throttle chamber, 20 ... A / T control unit (fail-safe control means), 22 ... abnormality determination means, 24 ... idle switch, 26 ... turbine Sensor (transmission input rotation sensor), 32... Variable resistor (soft idle detection means).

Claims (1)

(57) [Claims] 1. An automatic transmission which is connected to an engine which automatically opens a throttle valve by a predetermined amount when a cooling water temperature is low, and in which power transmission from an output side to an input side is cut off during coasting traveling. A fail-safe control device for an automatic transmission, which is provided with an abnormality determining means for determining an abnormality of a transmission input rotation sensor using a transmission output shaft rotation speed, wherein a throttle valve opening degree is low and a cooling water temperature is low. A soft idle that detects a value equal to or less than a reference value set to a value equal to or more than the predetermined amount based on an output value of a variable resistor provided in a throttle valve and outputs a signal to the abnormality determination means. Signal detecting means is provided, and when the soft idle signal detecting means outputs the signal, the abnormality determining means stops the abnormality determining process. Automatic fail-safe control system.