JPH0138987B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an automatic transmission control device for automobiles, and in particular, to a drive cable (vehicle speed This invention relates to prevention of erroneous control and abnormality protection caused by breakage of meter cables, breakage or short-circuiting of signal pick-up lines, breakage or short-circuiting of vehicle speed signal processing circuits, etc. (Prior art) A normal automatic shift control system uses a vehicle speed response signal and an engine output torque response signal or a throttle opening response signal as input signals, compares these two signals, and outputs a shift operation control signal. Has a circuit. The vehicle speed response signal is supplied, for example, by a known reed switch type vehicle speed sensor that detects the rotation speed of the drive shaft. This reed switch type vehicle speed sensor is turned on and off by a magnet MG that rotates in accordance with the rotation of the drive shaft, and a constant voltage is applied between both terminals to generate constant voltage pulses with a frequency that corresponds to the number of rotations of the drive shaft. utter. This vehicle speed sensor is placed near the drive shaft or inside the speedometer, and the output signal line leading to the control circuit may be disconnected. In this case, the same output signal as when the vehicle is stopped is usually generated. For example, in the case of a reed switch with one end connected to the body ground and the other end connected to a constant voltage circuit, it emits a constant voltage non-pulse continuous signal,
This is the same signal as when the vehicle is stopped. In such a case, the control circuit of the automatic transmission control system determines that the vehicle has stopped, and issues a transmission control signal to shift to a low-speed gear shift position (for example, 1st gear). When the vehicle is running at high speed, if the vehicle is suddenly downshifted to first gear, engine braking will occur suddenly and sharply, causing a large and dangerous shock and possibly causing transmission or engine failure. Therefore, Japanese Patent Application Laid-Open No. 57-73259 proposes that when the vehicle speed response signal suddenly decreases, a hold state is brought about to prevent gear shifting. However, depending on the driving situation of the vehicle, a signal similar to that in an abnormal situation may appear even if the signal loop is normal. For example, if the wheels are stopped (locked) due to sudden braking while driving at high speed, the vehicle speed signal will suddenly decrease in the same way as when the signal loop is broken or the vehicle is shortened. In such a case, it is preferable to smoothly release the abnormality set (hold) of the abnormality detection means and the control circuit. Therefore, in Japanese Patent Application Laid-Open No. 56-59601, when the vehicle speed signal suddenly decreases, a hold is held to prevent the gear shift from being performed, and when the vehicle speed signal rises, the hold is released as normal. (Problems to be Solved by the Invention) In any of the above conventional examples, for example, the cable that drives the rotational speed sensor (vehicle speed meter cable) may break, the sensor rotor (usually a permanent magnet) may come off, or Although the vehicle speed signal is interrupted, immediately after the abnormality, if the speed indicated by the vehicle speed signal gradually decreases due to rotor idling, etc., the abnormality detection will not work and the transmission gear will be changed (shifted). . SUMMARY OF THE INVENTION An object of the present invention is to perform an automatic speed change protection operation even in the event of an abnormality such as breakage of a drive cable of a rotational speed sensor or detachment of a rotor. [Structure of the Invention] (Means for Solving the Problems) When the vehicle speed signal suddenly changes in the deceleration direction, the speed stage of the automatic transmission is held, and then after a predetermined time _T1 , the change in the deceleration direction of the vehicle speed signal is small. If the hold is released, and if the vehicle speed signal after a predetermined time _T2 indicates that the vehicle speed is substantially zero, the automatic transmission continues to hold the speed gear, and if the vehicle speed signal indicates that the vehicle speed is substantially above zero. and a gear shift control device that releases the hold. (Function) When the drive cable of the rotational speed sensor is broken or the rotor comes off, the vehicle speed signal suddenly decreases, so the transmission is first held (protective operation).
Then, the hold is continued because the weight loss after T ₁ is large. After that, the vehicle speed signal is further referred to after T ₂ , and at this time the rotor has substantially stopped and the vehicle speed signal indicates substantially zero, so
The automatic transmission speed gear hold continues and remains in the protective hold state. In other words, it becomes an abnormal hold state. When the vehicle speed suddenly decreases under normal conditions, such as during sudden braking, the transmission is first held on hold (protective operation) until the vehicle speed signal suddenly decreases. If the weight loss after T ₁ is small, the hold is released there. Even if the weight loss is large, the vehicle speed has not reached zero after T ₂ , so
The hold is released. After the hold is released, automatic shift control is performed according to the driving state. (Example) FIG. 1 shows an example of the present invention. In this case, a reed switch RSW of a rotational speed sensor, which is a vehicle speed response signal generating means, connects a permanent magnet rotor (not shown) connected to a rotating vehicle speed meter cable (not shown) connected to a transmission output shaft. Opens and closes depending on the rotation of the The reed switch RSW is connected to the base of the transistor Tr ₁ via the resistor R1, and the collector of the transistor Tr ₁ is connected to the microprocessor 4.
1 interrupt input terminal IRQ (low level input: advances to interrupt when falling from high level to low level). Transistor Tr ₁ opens when reed switch RSW opens.
is on, a low level L is applied to IRQ, and when RSW is closed, transistor Tr ₁ is off, a high level H is applied to IRQ.
is applied, the microprocessor 41 executes an interrupt when the reed switch RSW changes from closed to open. Microprocessor (hereinafter referred to as
(referred to as CPU) 41 is the high level H of the IRQ input.
Flip-flop (interrupt flip-flop) that is set in response to the falling from low to low level L
, refer to the time count value and carry flag at that time, and if there is no carry flag, update the count value to the cycle register as cycle data of the vehicle speed signal, reset the clock counter, and immediately before entering the interrupt. Return to step. When the carry flag is activated, it means that there has been no change in the signal for a predetermined period of time, so data indicating the vehicle speed of zero (the cycle is infinite) is set in the cycle register, the clock counter is reset, and the carry flag is cleared. and returns to the step immediately before entering the interrupt. The clock counter always counts up or down at a predetermined period. Through this interrupt processing, data necessary to obtain vehicle speed data is constantly stored in the periodic register. A negative pressure switch that opens and closes at a predetermined pressure value depending on the negative pressure of the engine intake manifold.
A negative pressure switch VSW is provided to obtain a signal corresponding to the engine output torque, and this negative pressure switch VSW is connected to the base of the transistor _Tr2 via a resistor R2. When the switch VSW is open, the transistor Tr ₂ is on and a low level L is applied to the input port R4 of the CPU 41. When the switch VSW is closed, the transistor Tr ₂ is off and a high level H is applied to the input port R4. . CPU41 is input port R
Read the signal level of 4 and read whether the switch VSW is open or closed. An accelerator switch ASW that opens and closes when the accelerator pedal is depressed beyond a predetermined level is provided to obtain engine power indicator signals such as throttle opening signals _. connected to the base. When the switch ASW is open, the transistor Tr ₃ is on and a low level L is applied to the input port R7 of the CPU 41. When the switch ASW is closed, the transistor Tr ₃ is off and a high level H is applied to the input port R7. Ru. CPU41 is input port R
Read the signal level of 7 and read whether the switch ASW is open or closed. A solenoid driver 44 is connected to the output port O ₂ of the CPU 41, and a coil SSV of a shift solenoid valve of an automatic transmission 45 is connected to this driver 44. The automatic transmission 45 is a two-speed transmission of a known solenoid control type, and is in a first speed state when the coil SSV is energized, and is in a second speed state when it is not energized. High level H on output port _O2
When set, the transistor TR ₄ is turned off, the transistor Tr ₅ is turned off, and the transistor Tr ₆ is also turned off, the coil SSV is not energized and the automatic transmission 45 is in the second speed state. When a low level L is set at the output port _O2 , the transistor Tr ₄ is turned on, the transistor Tr ₅ is turned on, the transistor Tr ₆ is also turned on, the coil SSV is energized, and the automatic transmission 45 is placed in the first speed state. . Note that the transistor Tr ₆ is for monitoring the output state, and when the transistor Tr ₆ is off, the input port _K0 of the CPU 41 is at a low level L indicating the second speed setting output state, and when it is on, the first speed output state is set. This is a high level H. A constant voltage circuit 43 supplies a predetermined voltage to the CPU 41 and other electric circuits. IGSW is a key switch that is closed when the engine key switch is installed, and BAT is an on-board battery, which supplies power to the constant voltage circuit 43. Output port O ₁ of CPU 41 has runaway detection circuit 4
6 is connected. This circuit 46 is connected to the CPU while receiving a predetermined voltage from the constant voltage circuit 43.
The CPU 41 receives pulses of a substantially constant period given each time a predetermined control routine is executed, and when the pulses are interrupted, a reset signal is given to the CPU 41. The reset signal is applied to the reset terminal RESET of the CPU 41. The reset signal resets the CPU 41 at a low level L. FIG. 2 shows the speed change control operation of the CPU 41.
Note that this is a branch from the main routine, and at a predetermined step in the control of the main routine, the shift control shown in FIG. Go to control and repeat. The power is turned on to the CPU 41, the CPU 41 executes initialization, and after passing through the predetermined steps, an interrupt is generated.
When the CPU 41 sets the IRQ to enable and proceeds to shift control, the CPU 41 first refers to the initial flag in shift control (FIG. 2) (Step 1: hereinafter, the word "step" will be omitted in brackets). At this time, the initial flag has been set (it was set during the initialization described above), so the initial flag is cleared, the T ₀ timer (program timer with a T ₀ sec time limit) is set (2), and the process returns to the main routine. . Next, when the main routine proceeds to shift control, the process proceeds from steps 1 to 3 to check whether _T0 has timed out or not. If the time has not expired, the process returns to the main routine. When the time is over, reset the _T0 timer and
Calculate vehicle speed Vv ₁ (4). This is calculated based on the contents of the period register mentioned above. Next, calculate the vehicle speed change amount Vv ₀ −Vv ₁ between T ₀ and compare it with the reference value Aref.
(Five). Note that Vv ₀ is the previous vehicle speed calculation value stored in the vehicle speed register. Here, if Vv ₀ −Vv ₁ <Aref, it is unlikely that the electric circuit of the rotational speed sensor (RSW) is disconnected, the drive cable is broken, the rotor comes off, etc. switch on
Read the open/close status of ASW and VSW and step 15
~20, set the speed stages according to the relationships shown in Table 1 below.

〔Effect of the invention〕

As described above, the present invention focuses on the output characteristics of the rotational speed sensor when it is abnormal, and particularly focuses on the characteristics of the vehicle speed signal decreasing due to the rotor idling when the drive cable breaks or the rotor comes off. Since the automatic shift control is also held for safety, the safety of the automatic shift control is further increased.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a flowchart showing a speed change control operation by the microprocessor 41 shown in FIG. RSW: Rotational speed sensor reed switch (vehicle speed response signal generation means), VSW: Negative pressure switch,
ASW: accelerator switch, IGSW: key switch, BAT: on-board battery, 41: microprocessor, 42: speed change control device, 43: constant voltage circuit, 44: solenoid driver, 45: automatic speed change device.

Claims (1)

[Claims] 1. A vehicle speed response signal generating means for generating a vehicle speed response signal whose level fluctuates at a cycle corresponding to the vehicle speed; A vehicle speed signal processing device that processes the vehicle speed response signal and generates a vehicle speed signal indicating a value corresponding to the vehicle speed; The speed stage of the automatic transmission is determined in response to the engine output torque corresponding signal, the engine power indicator signal such as the throttle opening signal, the vehicle speed signal, and abnormality detection: When the vehicle speed signal suddenly changes in the direction of deceleration, the speed of the automatic transmission changes. Hold the step and then for the predetermined time T ₁
If the change in the deceleration direction of the rear vehicle speed signal is small, the hold is released, and if it is large, the hold is released for a predetermined period of time _T2.If the rear vehicle speed signal indicates that the vehicle speed is substantially zero, the automatic transmission continues to hold the speed gear. , a hold is released when the value substantially exceeds zero: a shift control device;