JPH057582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an automatic transmission that performs control to maintain a gear position as it is when a vehicle speed signal is abnormal.

[Prior Art] In a vehicle equipped with an automatic transmission, the gear position is determined according to the relationship between the vehicle speed, the throttle valve opening, and the gear position, as shown in FIG. 4, for example, and the gear position is automatically switched. is going on. In order to carry out such automatic shift control, it is necessary to read the vehicle speed signal and the throttle valve opening signal, as is clear from FIG. These signals are
In a typical configuration, the data is read into a microcomputer, and the range shown in FIG. 4 is checked to determine the gear position. Then, the on/off state of the shift solenoid is controlled according to the result of the determination. In the case of a four-speed transmission consisting of 1st speed, 2nd speed, 3rd speed, and OD, two speed change solenoids are generally used. When using these two shift solenoids, for example, if only the first shift solenoid is turned on, it will be 1st gear, if both shift solenoids are turned on, it will be 2nd gear, and if only the second shift solenoid is turned on, it will be 3rd gear. The gear shift control system is configured to switch to OD when both shift solenoids are turned off.

By the way, in Fig. 4, the vehicle speed and throttle
If the vehicle speed detection system becomes abnormal and the vehicle speed signal becomes zero in a high-speed driving state where the region determined by the valve opening is A, as is clear from Figure 4, the gear will suddenly drop from OD to 1st gear. This will impede high-speed driving.
In order to avoid such a situation, conventionally, two vehicle speed detection systems were provided to provide so-called redundancy, and if one system failed, the system could be switched to the other vehicle speed detection system to ensure uninterrupted operation. are doing.

[Problems to be Solved by the Invention] However, in the conventional system with redundancy as described above, two vehicle speed detection systems are required, and furthermore, abnormality determination for the two systems and switching control in the event of an abnormality are required. A method is required, and the entire system inevitably becomes complicated. Furthermore, if the two systems are in an abnormal state, downshifting of the gear position during high-speed driving is unavoidable, which causes problems.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a control device for an automatic transmission that allows stable driving even when an abnormality occurs in the vehicle speed detection system.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a vehicle speed sensor that detects a running signal of a vehicle, a throttle sensor that detects a signal according to engine load, and the vehicle speed sensor. and a shift solenoid that controls the shift based on signals from the throttle sensor; and an automatic shift control device that inputs signals from the vehicle speed sensor and the throttle sensor and outputs a shift control signal to the shift solenoid. , the automatic transmission control device comprises: a vehicle speed signal reading means for inputting a signal from the vehicle speed sensor; a throttle opening reading means for inputting a signal from the throttle sensor; a gear position determination means for inputting a signal and outputting a gear change control signal for determining a gear position; and whether or not the signal from the vehicle speed reading means and the gear position determined by the gear position determination means are within a predetermined range. a vehicle speed/gear position comparison means for determining whether the vehicle speed and the gear position are abnormal or not; and an abnormality determination means for determining whether or not the vehicle speed and the gear position are abnormal by the vehicle speed/gear position comparison means, and outputting an abnormality signal when the vehicle speed and the gear position are determined to be abnormal; The gear position maintaining means is configured to output a signal prohibiting gear shifting to the gear shifting solenoid based on the abnormal signal.

[Operation and Effects of the Invention] In the automatic transmission control device of the present invention, when the vehicle speed signal is not abnormal, the same speed change control as in the conventional method is of course performed, but when it is determined that the vehicle speed signal is abnormal, The gear position is maintained and fixed. Therefore, even if the vehicle speed signal becomes abnormal during high-speed driving, the high-speed gear will not be shifted down to the first gear.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration example of an automatic transmission control system to which the present invention is applied, and FIG. 2 is a functional block configuration for explaining one embodiment of a fail-safe control system when a vehicle speed signal is abnormal according to the present invention. 3 are diagrams for explaining the flow of processing by the functional block configuration shown in FIG. 2. In the figure, 1 is a vehicle speed sensor, 2 is a throttle/valve opening sensor (throttle sensor), 3 and 4 are signal conversion circuits, and 5 is a
CPU (processing unit), 6 and 8 are solenoid drive circuits, 7 and 9 are monitor circuits, 10 and 11 are shift solenoids, 12 is a signal reading section, 13 is a vehicle speed signal judgment section, 14 is a shift judgment section, 15 1 indicates a solenoid control unit, and 16 indicates a shift determination table.

In FIG. 1, a vehicle speed sensor 1 is generally composed of a reed switch and a magnet, and outputs a pulse signal with a frequency corresponding to the vehicle speed.
The throttle valve opening sensor 2, which detects a signal according to the vehicle speed, uses a volume resistor and outputs a linear analog signal corresponding to the opening. The method is not particularly limited to the above method. The signal conversion circuits 3 and 4 are connected to the CPU 5.
If it is a pulse signal, it is converted to a predetermined processing level so that it can be processed, and if it is an analog signal, it is converted to a digital signal of a predetermined processing level. The CPU 5 has a memory that stores control programs necessary for performing automatic gear shift control and a gear shift determination table as shown in FIG. It performs automatic gear shift control. Solenoid drive circuits 6 and 8 are CPU
According to the command 5, signals from the vehicle speed sensor and the throttle sensor are inputted to output a shift control signal to turn on/off the shift solenoids 10 and 11, and the monitor circuits 7 and 9 control the shift The state of the solenoids 10 and 11 is monitored.

With the above configuration, the CPU 5 reads the vehicle speed signal and the throttle valve opening signal through the signal conversion circuits 3 and 4, determines whether the vehicle speed signal is abnormal, and then changes the gear position according to the relationship shown in FIG. The speed change control is performed by controlling the solenoid drive circuits 6 and 8 according to the judgment result. It should be noted that the shift solenoids 10 and 11 are used to change the gear stage as described above by a combination of their on/off states.

Next, the fail-safe control system when the vehicle speed signal is abnormal according to the present invention will be explained in detail with reference to FIGS. 2 and 3.

In FIG. 2, a signal reading section 12 reads a vehicle speed signal and a throttle valve opening signal input as pulse signals, and uses a counter to detect the vehicle speed and valve opening according to the period or frequency. The vehicle speed signal determination section 13 monitors the states of the two shift solenoids via the solenoid control section 15, and determines whether or not the vehicle speed signal is abnormal. As a method for this determination, for example, the state of the shift solenoid, that is, the gear position is 3.
If the vehicle speed signal is read as "0" even though the vehicle is in a high speed state higher than the vehicle speed, it is determined that there is an abnormality.
The shift determination table 16 stores a table as shown in FIG. 4 for determining the gear position from the throttle valve opening degree and vehicle speed, and the control contents of the shift solenoid corresponding to the gear position. The gear shift determination unit 14 includes vehicle speed/gear comparison means 2
0, on condition that the vehicle speed signal is not abnormal, the throttle opening 18 and the vehicle speed reading means 19
In the gear position determining means 23, which outputs a gear change control signal that determines the gear position by inputting a signal from On the condition that the signal is abnormal, the shift solenoid is maintained in the previous state, the gear stage is maintained as it is, and the shift stage is not changed.
That is, when the abnormality determination means 21 determines that there is an abnormality, an abnormality signal is output. Then, based on the abnormality signal, the gear stage maintaining means 22 prohibits the output of the gear shift signal to the gear shifting solenoids 10 and 11. The solenoid control section 15 sends out a control signal to turn on/off the shift solenoid in accordance with a command from the shift determination section 16.
FIG. 3 shows the flow of processing according to the configuration shown in FIG. 2, and will be explained below.

Initialize the system. This process is performed, for example, when the ignition switch is turned on. Perform the following processing.

Read the throttle valve opening. Perform the following processing.

Read vehicle speed. Perform the following processing.

Check whether the vehicle speed signal is "0" or not.

If YES, perform the process; if NO, perform the process.

Monitor the solenoid signal and check the gear position. Perform the following processing.

Check whether the vehicle speed detection system is abnormal.

If YES, perform the process; if NO, perform the process.

Note that whether or not there is an abnormality is determined not only by whether or not the gear is in 3rd gear or higher (despite the vehicle speed being "0"), but also by determining whether or not there is an abnormality before or after the vehicle speed signal. It goes without saying that the rate of change and other conditions may be used.

The solenoid signal continues to be maintained in the state monitored by the above processing. In other words, the gear position is maintained as it was before and is not changed. Return to next process.

Referring to the gear shift determination table, the gear position is determined based on the vehicle speed and throttle valve opening. Perform the following processing.

The solenoid output is controlled according to the above processing results. Return to next process.

As is clear from the above processing flow, as long as the vehicle speed signal is determined to be abnormal, the process repeats the loop from to, and the gear position is changed to
The previous state will continue to be maintained and cannot be switched. Therefore, once the vehicle has stopped, the vehicle cannot start because the vehicle is in a high speed gear. Therefore, if you turn off the engine and start it again, you will be able to start from 1st gear by going through the process of initializing, but you will be able to start from 1st gear, but you will be able to start from 1st gear. No switching takes place. By locking (fixing) the gear position in this manner, it is possible to avoid the trouble of downshifting during high-speed driving due to an abnormality in the vehicle speed signal. Furthermore, when the vehicle speed signal is no longer abnormal, the process moves to the normal process or the previous process, thus returning to normal speed change control. That is, the loop that moves from the process to the process or from the process to the process becomes regular shift control, that is, conventional shift control.

As is clear from the above description, the present invention is characterized by adopting fail-safe control that fixes the gear position to the previous state when the vehicle speed signal becomes abnormal, and is not limited to the above embodiment. Needless to say, the present invention is not limited to the above, and can be applied with various modifications. For example, the vehicle speed detection system may be one system, but it goes without saying that the present invention may be applied to a conventional system using two systems.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a configuration example of an automatic transmission control system to which the present invention is applied; FIG. 2 is a functional block configuration diagram for explaining one embodiment of an automatic transmission control device according to the present invention; FIG. 3 is a diagram for explaining the flow of processing according to the functional block configuration shown in FIG. 2, and FIG. 4 is a diagram for explaining the relationship between vehicle speed, throttle valve opening/closing, and gear position. In the figure, 1...vehicle speed sensor, 2...throttle sensor, 10, 11...shift solenoid, 17...
... Automatic transmission control device, 18 ... Throttle opening reading means, 19 ... Vehicle speed signal reading means, 20
. . . Vehicle speed/gear comparison means, 21 . . . Abnormality determination means, 22 .

Claims (1)

[Scope of Claims] 1. A vehicle speed sensor that detects a running signal of the vehicle; a throttle sensor that detects a signal according to the engine load; and a shift that controls shifting based on the signals from the vehicle speed sensor and the throttle sensor. and an automatic shift control device that receives signals from the vehicle speed sensor and throttle sensor and outputs a shift control signal to the shift solenoid, and the automatic shift control device receives the signals from the vehicle speed sensor. A vehicle speed signal reading means for inputting the signal; a throttle opening reading means for inputting the signal from the throttle sensor; and a gear change control signal for inputting the signals from the throttle opening and vehicle speed reading means and outputting a shift control signal for determining a gear position. a gear position determining means for determining whether the signal from the vehicle speed reading means and the gear position determined by the gear position determining means are within a predetermined range; Abnormality determination means for determining whether the vehicle speed and the gear position are abnormal by means of gear comparison means, and outputting an abnormality signal when it is determined that the vehicle speed and the gear position are abnormal; and a signal for prohibiting the gearshift solenoid from shifting based on the abnormality signal. 1. A control device for an automatic transmission, comprising a gear position maintaining means for outputting a gear position. 2. When the signal from the vehicle speed reading means is zero in the vehicle speed/gear comparing means and the gear determined by the gear determining means is 3rd gear or higher, the abnormality determining means outputs an abnormal signal. 2. A control device for an automatic transmission according to claim 1, wherein the automatic transmission control device is configured to: 3. Claim 1, wherein when the abnormality determination means does not output an abnormality signal, the automatic transmission control device outputs a transmission control signal to the transmission solenoid determined by the gear position determination means. A control device for the automatic transmission described above.