JPH0297764A - Fail safe device for electronically controlled automatic transmission - Google Patents

Abstract

PURPOSE:To prevent a trouble from interfering with all the controls, even when a car speed sensor is in trouble, by providing an estimating means which respectively estimates an engine speed from a turbine speed, engine speed from an output shaft speed and the turbine speed from the output shaft speed and an estimating means which performs estimation in a reverse way to the above. CONSTITUTION:In the case of an engine speed sensor 23 in trouble, an engine speed is estimated by the first or second engine speed estimating means from a turbine speed or an output shaft speed. In the case of a turbine speed sensor 24 in trouble, the turbine speed is estimated by the first or second turbine speed estimating means from the engine speed or the output shaft speed. And in the case of an output shaft speed sensor 25 in trouble, the output shaft speed is estimated by the first or second output shaft speed estimating means from the engine speed or the turbine speed. While in the case of all the sensors 23, 24, 25 in trouble, all the speeds are set to a maximum value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a speed control device using an electronically controlled automatic transmission mounted on a vehicle.

(Prior Art) Conventionally, in an electronically controlled automatic transmission system that controls the gear position of a vehicle, two vehicle speed sensors are installed as a fail-safe in the event of a failure of the vehicle speed sensor that detects the speed of the vehicle.
They monitored each other's output, and the normal sensor was used for control.

(Problems to be Solved by the Invention) However, since the conventional device uses two vehicle speed sensors, an increase in cost is unavoidable.

Therefore, an object of the present invention is to create a device that uses conventionally used sensors and has only one system of vehicle speed sensors, so that even if this vehicle speed sensor fails, the overall control will not be affected. do.

[Structure of the invention]

(Means for Solving the Problems) The technical means used in the present invention to solve the above problems are an electronically controlled automatic transmission comprising an automatic transmission and an electronic control means for controlling the automatic transmission; An engine rotation speed detector that measures the rotation speed of the input shaft of a machine, a turbine rotation speed detector that measures the rotation speed of the turbine rotation shaft of an automatic transmission, and an output shaft rotation speed detector that measures the rotation speed of the output shaft of an automatic transmission. a first engine rotation speed estimation means for estimating the engine rotation speed from the turbine rotation speed; a second engine rotation speed estimation means for estimating the engine rotation speed from the output shaft rotation speed; a turbine rotation speed from the engine rotation speed; a first turbine rotation speed estimation means for estimating the turbine rotation speed from the output shaft rotation speed; a first output shaft rotation speed for estimating the output shaft rotation speed from the engine rotation speed; estimating means, second output shaft rotation speed estimating means for estimating output shaft rotation speed from the turbine rotation speed, and first engine rotation speed detector failure determination for determining failure of the engine rotation speed detector using the turbine rotation speed. means, second engine rotation speed detector failure determination means for determining failure of the engine rotation speed detector using the output shaft rotation speed, and first engine rotation speed detector failure determining means for determining failure of the turbine rotation speed detector using the engine rotation speed. Turbine rotation speed detector failure determination means, second turbine rotation speed detector failure determination means for determining failure of the turbine rotation speed detector using the output shaft rotation speed, and output shaft rotation speed detection using the engine rotation speed. a first output shaft rotation speed detector failure determination means for determining a failure of the output shaft rotation speed detector, a second output shaft rotation speed detector failure determination means for determining a failure of the output shaft rotation speed detector using the turbine rotation speed; 1 When the engine rotation speed detector failure determination means detects a failure, the second
The engine rotation speed estimating means is activated, and when the second engine rotation speed detector failure determination means detects a failure, the first engine rotation speed estimation means is activated, and the first turbine rotation speed detector failure determination means detects the failure. Sometimes, the second turbine rotation speed estimating means is activated, and when the second turbine rotation speed detector failure determination means detects a failure, the first turbine rotation speed estimation means is activated, and the first output shaft rotation speed detector malfunctions. Control means for operating the second output shaft rotation speed estimation means when the determination means detects a failure, and for operating the first output shaft rotation speed estimation means when the second output shaft rotation speed detector failure determination means detects a failure. , was prepared.

Furthermore, the engine rotation speed setting means sets the engine rotation speed to the maximum value, the turbine rotation speed setting means sets the turbine rotation speed to the maximum value, and the output shaft rotation speed setting means sets the output shaft rotation speed to the maximum value. , the control means comprising:
When both the first and second engine rotation speed detector failure determination means detect a failure, the engine rotation speed setting means is activated, and when both the first and second turbine rotation speed detector failure determination means detect a failure, the turbine rotation speed setting means is activated. The rotation speed setting means is activated, and when both the first and second output shaft rotation speed detector failure determining means detect a failure, the output shaft rotation speed setting means is activated.

(Operation) According to the above technical means, when the engine rotation sensor fails, this failure is detected by the first and second engine rotation speed detector failure determination means, and the first or second engine rotation speed estimation The engine rotation speed is estimated by means of the turbine rotation speed or the output shaft rotation speed. When the turbine rotation sensor fails, the failure is detected by the first and second turbine rotation speed detector failure determination means, and the first or second turbine rotation speed estimation means determines whether the turbine rotation speed is the engine rotation speed or the output power. Estimated from shaft rotation speed. If the output shaft rotation sensor fails,
This failure is detected by the first and second output shaft rotational speed detector failure determination means, and the output shaft rotational speed is estimated by the first or second output shaft rotational speed estimation means based on the engine rotational speed or the turbine rotational speed. Therefore, when each sensor fails, each rotation speed is estimated by other sensors.

Further, if the engine rotation sensor, turbine rotation sensor, and output shaft rotation sensor all fail, all rotation speeds are set to the maximum value.

(Example) An example using the present invention will be described below based on the drawings. In this example, a conventional 4-speed (with overdrive) automatic transmission is used. ing.

The operation of this automatic transmission will be explained with reference to FIG.

Turbine shaft 600, which is the input shaft of overdrive mechanism 607, is coupled to the engine via a torque converter. This turbine shaft 600 is connected to a carrier 609 of a Ti star gear system. A planetary pinion 610 rotatably supported by a carrier 609 is connected to an input shaft 611 of a gear transmission mechanism 608 via an OD planetary gear 601. Also planetary pinion 6
10 meshes with sun gear 612. sun gear 61
2 and the carrier 609 is a one-way clutch 606.
and an OD clutch CO are provided. sun gear 612
An OD brake BO is provided between the housing 613 and the housing 613. A forward clutch C1 is provided between the input shaft 611 and the intermediate shaft 614 of the gear transmission mechanism 608.

Further, a direct clutch C2 is provided between the input shaft 611 and the sun gear shaft 615. sun gear shaft 615
A second brake B1 is provided between the housing 613 and the housing 613. Carrier 6 connected to output shaft 605
A planetary pinion 6 rotatably supported by 17
19 is an intermediate shaft 614 via a gear and a carrier 618
is connected to. Further, the planetary pinion 619 meshes with the sun gear shaft 615. Planetary pinion 621 meshes with carrier 617 and sun gear shaft 615. Planetary pinion 621 and housing 6
13, a 1st and Rev brake B2 is provided. Further, a one-way clutch 616 is provided between the planetary pinion 621 and the housing 613.

In this automatic transmission, clutches CO and CI.

The relationship between C2, brakes BO, Bl, and B2 and the gears is as shown in the table below.

○: Engagement ×: Disengagement plan This clutch Co, CI, C2 and brakes BO, B
1. The engagement and release of B2 is controlled by the hydraulic circuit shown in FIG.

Referring to FIG. 2, a hydraulic pump 70 is connected to an oil reservoir 701.
The pressure regulating valve 703, which is controlled by the line pressure control solenoid valve 48, regulates the hydraulic pressure of the line pressure oil passage 704. Line pressure oil path 7
04b is connected to a line pressure oil passage 704 through a pressure regulating valve 703, which includes a solenoid pulp 41 for controlling the clutch 02, a solenoid pulp 42 for controlling the clutch 02, a solenoid valve 43 for controlling the brake 81. brake 8
1 control solenoid valve 44. They are connected to manual valves 705, 706, 707, 708, and 709, respectively, via brake B2 control solenoid valves 45. Also, manual valves 705, 706, 707
．． 708. T.

9 is directly connected to the output of a hydraulic pump 702.

And manual valve 705.706707.70
Clutch CO, clutch C2, brake BO, and brake BL are connected to the outputs of 8, respectively. The output of manual valve 709 is connected to brake B2 via valve 710. Valve 710 is connected to shift valve 711 via low/reverse prohibition solenoid valve 46. Shift valve 711 is also connected to manual valve 706. This shift valve 711 is
It moves in response to the operation of the shift lever, and hydraulic pressure from a hydraulic pump 702 is applied to the inside when the shift lever is not in the P range. Furthermore, oil pressure is applied to the clutch C1 during 1st, 2nd, 3rd, and OD. Then, hydraulic pressure is supplied to the manual valve 706 in the L and 2 ranges, and hydraulic pressure is supplied to the low and reverse prohibition solenoid valves 46 in the L and R ranges.

With this configuration, when the clutch CO control solenoid valve 41 is opened, the manual valve 705 moves, the output of the hydraulic pump 702 is applied to the clutch CO, and the clutch CO is engaged. If the clutch CO control solenoid valve 41 is closed, no hydraulic pressure is applied to the clutch CO.
Clutch CO is released.

Clutch C1 includes 1st, 2nd, 3rd and OD.
At times, hydraulic pressure is applied and engaged, and when in other ranges, no hydraulic pressure is applied and it is released.

In the clutch C2, when the clutch 02 control solenoid valve 42 is opened, the manual valve 706 is moved, hydraulic pressure is applied to the clutch C2, and the clutch CO is engaged. If the clutch 02 control solenoid valve 42 is closed, no hydraulic pressure is applied to the clutch C2, and the clutch C
2 is released. However, due to the shift valve 711, 2
When in the range mode, hydraulic pressure is supplied to the manual valve 706, and the hydraulic pressure to the clutch C2 is cut off regardless of the movement of the clutch C2 control solenoid valve 42.

In the brake BO, when the brake BO control solenoid valve 43 is opened, the manual valve 707 moves, and no hydraulic pressure is applied to the brake BO (and the brake BO is released.The brake BO control solenoid valve 43 is closed). For example, hydraulic pressure is applied to the brake BO, and the brake BO is engaged.

In the brake B1, when the solenoid valve 44 for controlling the brake 81 is opened, the manual valve 708 is moved, hydraulic pressure is no longer applied to the brake B1, and the brake B1 is released. When the brake 81 control solenoid valve 44 is closed, hydraulic pressure is applied to the brake B1, and the brake B1 is engaged.

In the brake B2, when the brake B2 control solenoid valve 45 is opened, the manual valve 709 is moved, so that hydraulic pressure is no longer applied to the brake B2, and the brake B2 is released. When the brake 82 control solenoid valve 45 is closed, the brake B2 is activated via the valve 710.
Hydraulic pressure is applied to the brake B2, and the brake B2 is engaged. However, when the low and reverse prohibition solenoid valves 46 are turned on in the R and L ranges, hydraulic pressure is applied to the valve 710, cutting off the supply of hydraulic pressure to the brake B2.
Release brake B2.

In other configurations, reference numeral 712 is a lock-up control valve, and when the lock-up control solenoid valve 47 is turned on, the output shaft of the engine and the turbine rotation shaft 600 are directly connected to enter a lock-up state.

Each solenoid valve is driven by an electronic control circuit, which will be described later, and the clutches and brakes are controlled so that the relationships shown in Table 1 are achieved according to the driving conditions.

Further, each solenoid pulp is repeatedly turned on and off at a relatively high frequency by an electronic control circuit to be described later, and by controlling the duty ratio, the opening degree of each manual valve can be adjusted. When the duty ratio is increased, the manual valve opens wide and the hydraulic pump 702
The hydraulic pressure generated by this is quickly applied to each clutch and brake, increasing the operating speed of each clutch and brake.

In addition, when the duty ratio is lowered, the opening degree of the manual valve becomes smaller, and it takes time for the hydraulic pressure generated by the hydraulic pump 702 to reach each clutch and brake, and the operating speed of each clutch and brake becomes slower. By controlling the duty ratio, the operating speed of each clutch/brake can be adjusted, reducing the shock that occurs when each clutch/brake is engaged, and improving transmission efficiency.

FIG. 3 shows an electronic control circuit that drives each solenoid pulp in the hydraulic circuit.

A constant voltage power a! is connected to the terminals of the battery 20 mounted on the vehicle via the ignition switch 21. The input end of X22 is connected. The output terminal of the constant voltage power supply 22 is connected to power supply terminals VCC and GND of the central processing unit (CPU). The constant voltage power supply 22 is for converting the output voltage of the battery 20 into a voltage at which the central processing unit CPU can operate.

Each input terminal of the CPU (central processing unit) is connected to an engine rotation sensor 23. Turbine rotation sensor 24° output shaft rotation sensor 25. Throttle sensor 26° Neutral start switch 27. Overdrive cut switch 31
．． An idle switch 32 and a brake switch 33 are connected.

In FIG. 3, the input interfaces of each sensor and switch are omitted for simplicity.

The engine rotation sensor 23 is a sensor that detects the rotation speed of the vehicle engine. The engine rotation sensor is disposed near the output shaft of the engine and outputs a pulse signal having a frequency corresponding to the engine rotation speed. In this example,
The engine rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of the ring gear attached to the output shaft of the engine.
Outputs 0 pulse. This output is the central processing unit cp
sent to u.

The turbine rotation sensor 24 is a sensor that detects the rotation speed of the turbine. The turbine rotation sensor is disposed near the turbine rotation shaft and outputs a pulse signal having a frequency corresponding to the rotation speed of the turbine. In this embodiment, the turbine rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of a gear attached to the turbine shaft 600, and outputs 57 pulses for one rotation of the gear. This output is sent to the central processing unit (CPU).

The output shaft rotation sensor 25 is a sensor that detects the rotation speed of the output shaft of the automatic transmission. The output shaft rotation sensor is disposed near the output shaft of the automatic transmission, and outputs a pulse signal having a frequency corresponding to the rotation speed of the output shaft of the automatic transmission. In this embodiment, the output shaft rotation sensor is an electromagnetic pickup type rotation sensor installed opposite the teeth of a gear attached to the output shaft, and outputs 18 pulses for one rotation of the gear. This output is sent to the central processing unit CPU. Note that the output shaft rotation sensor may be replaced with another type of vehicle speed sensor that detects the speed of the vehicle, as long as the relationship between the output shaft of the automatic transmission and the rotational speed of the wheels is clearly known.

The throttle sensor 26 is a sensor that detects the opening degree of the throttle valve of the engine. The throttle sensor includes a digital 2-mechanical throttle sensor that detects the rotation angle of the throttle valve with a switch and divides the opening of the throttle valve, and a digital two-mechanical throttle sensor that converts the rotation angle of the throttle valve into a voltage value and uses an A/D converter. There are analog and electric throttle sensors that are used to divide the throttle valve opening. In the present invention, both throttle sensors are provided and used selectively, but in a normal device, only one of them may be used. The throttle sensor outputs a signal obtained by dividing the opening degree of the throttle valve into 16 parts from four signal lines. Fully closed state is θO2
The fully open state is assumed to be θ15. Between θ0 and θ15 is θ1~θ
14.

The neutral start switch 27 detects the position of the shift lever, and is a D (drive) range switch and an L (low) range switch.

2 (second) range switch, 3 (third) range switch, N (neutral) range switch, R (reverse) range switch and P (parking) range switch, D, L, 2°3, N, R, Detect each range of P.

The overdrive cut switch 31 is a switch operated by the driver, and is used to prohibit/disable overdrive.
This is a switch to set permissions.

Instead of this overdrive cut switch, for example, an interface may be provided that manually inputs an overdrive cut signal from the constant speed traveling device to prevent speed increase during constant speed traveling by the constant speed traveling device.

The idle switch 32 is a sensor that detects the idle state of the engine, and its contact is turned ON when the engine is idle (in this embodiment, the throttle opening is 1.5% or less).

The brake switch 33 detects whether the brake is on or off.

A clutch C is connected to each output terminal of the central processing unit CPU.
O control solenoid valve 41. Clutch 02 control solenoid pulp 42. Brake 81 control solenoid valve 43. Brake 81 control solenoid valve 44.
Brake B2 control solenoid valve 45. Solenoid valve for inhibiting low/reverse shift 46. A solenoid valve 47 for lock-up control and a solenoid valve 48 for line pressure control are connected. In FIG. 3, the output interface or drive device for each solenoid is omitted for simplicity. Each solenoid valve is controlled by a central processing unit CPU.

The central processing unit CPU has internal memories such as RAM and ROM, timers, and registers, and when the ignition switch is turned on, the central processing unit CPU
When voltage begins to be supplied to , the main routine shown in FIG. 4 begins to be executed.

FIG. 4 is a flowchart of the main routine of the central control unit CPU, vehicle speed sensor interrupt, turbine rotation sensor interrupt, engine rotation sensor interrupt, and scheduled interrupt.

(Main Routine) When the central control unit CPU starts, it first sets the input/output direction of each output boat, initializes each memory, and sets the presence/absence of interrupts (step 50).
).

After that, an input/output reading routine is executed to read the status of each sensor and switch connected to the input, remove noise, and set data according to the status of each sensor and switch (step 51).

Next, a rotational speed calculation processing routine is executed to calculate the vehicle speed, turbine rotational speed, and engine rotational speed (step 52).

The engine rotation speed NB is calculated using the following formula.

Note that since the output from the engine rotation sensor has a high frequency, it is calculated after dividing the frequency by eight.

n E(i-1) + n Ei NE Child PCOi 8 frequency division 60nEi=
X
8xlO-' 120 where, nEi: Engine rotation speed due to this pulse, TEi
: Time count until the edge of the first pulse that exceeds 10m5 from the previous pulse, Pct! The number of pulses during i s is 8×10−h: the minimum unit of detection time (8 μs).

Calculation of the turbine rotation speed NT is performed using the following formula.

Note that since the output from the turbine rotation sensor has a high frequency, the frequency is divided by four before calculation.

n T(i-1) + n Ti NT = PCTt d division 60nTi=
x xTTi
8X10-' 57 Here, nTi: Turbine rotation speed due to the current pulse, TTi
: Time count to the edge of the first pulse exceeding loms from the previous pulse, PCTi : Number of pulses in TTi.

Calculation of the output shaft rotation speed NO is performed using the following formula.

n 0 (i-1) + n 0i NO= PCOi 1 60no
t= x x
TOi 8xlO-18 where, not: number of output shaft rotations due to the current pulse, TOi: time count to the edge of the first pulse exceeding 10 m5 from the previous pulse, PCOi S TEi number of pulses.

The first output shaft rotation speed NO after the vehicle stops (determined in a scheduled interrupt routine to be described later) is calculated as follows: 144+n0i No=.

Since the gear ratio of the output shaft and the axle and the radius of the wheels are determined in advance, the vehicle speed can be determined from the output shaft rotational speed NO.

Vehicle acceleration AG is determined by the following formula.

Not 2: When No(i-1), Not-No(i-1) IAG=
XTOi
8X10-'The first calculation after the vehicle stops is Not-1441 AG= XTOi
Let's call it axlo-6. Also, Not <
When No (i-1), set AC to the maximum value (¥FF).

Next, a control vehicle speed difference and slip ratio calculation routine is executed, and a control vehicle speed difference and slip/knob ratio are determined (step 53). The turbine slip ratio 5LPt is determined by the following equation.

T SLPt = X100 (%) E Next, a line pressure control/shift control routine is executed, and line pressure setting and control, control mode setting, and shift judgment are performed (steer knob 54).

The line pressure set value is set by the throttle opening and turbine rotation speed. The line pressure solenoid is duty-driven according to this setting.

In the shift control, whether or not a shift is to be determined is determined based on a shift diagram created in advance using the throttle opening, vehicle speed, and current shift position.

When the above process is completed, it is determined in the mill line pressure control/shift control routine that shifting is possible, and if the gear is not currently being shifted, the gear shifting processing routine is executed to perform the shifting process.

Next, a lockup determination routine is executed, and if the lockup has changed, a lockup processing routine is executed to process the lock amplifier. Here, engine brake control is performed as part of the lock-up process. Here, when the throttle opening is fully closed (idle contact on) and the vehicle speed is above the set speed (15 km/h), the frontage/tuck-up solenoid is turned on and directly connected to the engine speed and turbine speed regardless of the shift stage. Apply engine braking. Idle contact off or engine rotation speed>turbine rotation speed for 0.6 seconds
After the elapse of time, a gear change judgment is made based on the gear position at that time.

Next, a skort control routine is executed, and when the range deviates from the neutral range when the vehicle is stopped, the skort control is performed by temporarily raising the gear stage to 3rd to soften the shock (step 61).

Next, fail-safe processing is performed (step 64).

Finally, an output control routine is executed to perform output control (step 65).

(Interrupt routine) The outputs of the output shaft rotation sensor, turbine rotation sensor, and engine rotation sensor are each connected to the interrupt input terminal of the central processing unit CPU, and each time the voltage level of the interrupt terminal changes, the output shaft Rotation sensor interrupt routine, turbine rotation sensor interrupt routine,
An engine rotation sensor interrupt routine is executed.

In the output shaft rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and then a calculation flag for calculating the output shaft rotation speed is turned on. Next, a failure of the turbine rotation sensor and the engine rotation sensor is determined.

When it is determined that the turbine rotation sensor has failed, a failure determination flag TOFL of the turbine rotation sensor by the output shaft rotation sensor is set to 1. In addition, when the engine rotation sensor is determined to be malfunctioning, the engine rotation sensor fail determination flag EOFL by the output shaft rotation sensor is set to 1 (
Steps 66-68). This failure determination is performed by comparing the output shaft rotation speed, the turbine rotation speed, and the engine rotation speed.

In the turbine rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and when the interrupt is counted four times in order to divide the frequency of the human power pulse by four, the calculation flag for calculating the turbine rotation speed is turned on. Then, a failure of the engine rotation sensor and the output shaft rotation sensor is determined.

When the engine rotation sensor is determined to be in failure, the failure determination flag ETFL of the engine rotation sensor by the cylinder rotation sensor is set to 1. In addition, when the output shaft rotation sensor is determined to be malfunctioning, the failure determination flag 0TFL of the output shaft rotation sensor by the turbine rotation sensor is set to 1 (
Steps 69-71). This failure determination is performed by comparing the turbine rotation speed, engine rotation speed, and output shaft rotation speed.

In the engine rotation sensor interrupt routine, first, the time at the time of the interrupt is read from a timer, and when the interrupt is counted 8 times in order to divide the input pulse by 8, a calculation flag for calculating the engine rotation speed is turned on. Then, it is determined whether the output shaft rotation sensor and the turbine rotation sensor are out of order.

When it is determined that the turbine rotation sensor has failed, a failure determination flag TEFL of the turbine rotation sensor by the engine rotation sensor is set to 1. Also, when the output shaft rotation sensor is determined to be malfunctioning, the output shaft rotation sensor fail determination flag 0EFL by the engine rotation sensor is set to 1 (
Steps 72-74). This failure determination is performed by comparing the engine rotation speed, the output shaft rotation speed, and the turbine rotation speed.

The central control unit (CPU) has regular interrupts that occur every predetermined period of time. In this example, 4 m
A scheduled interrupt routine is executed every s. Here, first, various timers used for control are subtracted (step 75).

Next, it is determined whether the vehicle has stopped (step 76). In this example, vehicle stopping speed N5top=144rp
Vehicles shall be stopped below n+ (approximately 3km). In addition, the input frequency T s top to the central control unit CPU
When there is no pulse of =23.13m5 or more, the vehicle is stopped.

The details of each control will be explained below based on the flowchart.

(Rotational speed calculation processing routine) FIG. 5 is a flowchart of the rotational speed calculation processing routine.

First, the output shaft rotation speed and vehicle acceleration are calculated. In each input side input, if both the fail flag EOFL of the output shaft rotation sensor by the engine rotation sensor and the fail flag TOFL of the output shaft rotation sensor by the turbine rotation sensor are off, the output shaft rotation fail flag OFL is turned off. , the output shaft rotation speed No. is calculated based on the above-mentioned calculation formula. Note that the output shaft rotation speed No. is determined only when the output shaft rotation sensor interrupt is performed and the calculation flag is turned on. When the calculation is completed, the calculation flag is cleared (steps 120 to 122). When either the fail flag EOFL or the fail flag TOFL is on, the fail flag OFL of the output shaft rotation sensor is turned on, and furthermore, the turbine rotation sensor is failed. If not, the output shaft rotation speed is calculated using the output value of the turbine rotation sensor, and if the turbine rotation sensor is malfunctioning but the engine rotation sensor is not malfunctioning, the output shaft rotation speed is calculated using the output value of the engine rotation sensor. Calculate the number (
Steps 123-127). Thereafter, vehicle acceleration AG is calculated based on the above-mentioned formula using the determined output shaft rotation speed (step 128). Output shaft rotation sensor, turbine rotation sensor.

If any engine rotation sensor is out of order, the vehicle acceleration is not calculated and the output shaft rotation speed NO is set to the maximum value (step 129). Note that the speed of the vehicle can be determined from the output shaft rotational speed because the gear ratio between the output shaft and the wheels and the radius of the wheels are determined in advance.

When determining the output shaft rotation speed from the other rotation sensors mentioned above, the following conversion formula is used.

Output shaft rotation speed N0 = NTX shift stage gear ratio = NEX shift stage gear ratio (when lock-up is on) = NE
X shift stage gear ratio (at lock-up off and NO≧200 Orpm) = NEX shift stage gear ratio X0.985 (at lock-up off and 11000 rpm≦NE<200 Orpm) = Nf! X shift stage gear ratio If any of the fail flags ETFL of the turbine rotation sensor by the sensor are off, the turbine rotation fail flag TF
L is turned off, and the turbine rotational speed NT is calculated based on the above-mentioned calculation formula. Note that the turbine rotation speed NT is calculated only when the calculation flag is turned on during the turbine rotation sensor interrupt. When the calculation is completed, the calculation flag is cleared (steps 130 to 132). Fail flag 0TF
When either L or the fail flag ETFL is on, the fail flag TFL of the turbine rotation sensor is turned on, and if the engine rotation sensor is not malfunctioning, the turbine rotation speed is calculated using the output value of the engine rotation sensor, If the engine rotation sensor is out of order but the output shaft rotation sensor is not out of order, the output value of the output shaft rotation sensor is used to calculate the turbine rotation speed, and if both the engine rotation sensor and output shaft rotation sensor are out of order, the turbine rotation speed is calculated. Set the maximum value to the rotation speed NT (steps 133-1)
38).

When determining the turbine rotation speed from the other rotation sensors mentioned above, the following conversion formula is used.

Turbine rotation speed NT = NOX shift stage gear ratio = NEX shift stage gear ratio (when lock-up is on) = Nt
! x shift stage gear ratio (at lock-up off and NU≧200Orpm) = NI! x Shift stage gear ratio I do.

In each human power interrupt, if both the engine rotation sensor fail flag 0EFL by the output shaft rotation sensor and the engine rotation sensor fail flag TEFL by the turbine rotation sensor are OFF, the engine rotation fail flag EFL is turned OFF, and the above calculation formula is used. The engine rotation speed NH is calculated based on the following. In addition, engine speed NE
is performed only when the calculation flag is turned on during the engine rotation sensor interrupt. When the calculation is completed, the calculation flag is cleared (steps 139 to 141).

Fail flag 0EFL or fail flag TEFL
When either is on, the fail flag EFL of the engine rotation sensor is turned on, and if the turbine rotation sensor is not malfunctioning, the engine rotation speed is calculated using the output value of the turbine rotation sensor, and the turbine rotation sensor is malfunctioning. If the output shaft rotation sensor is not malfunctioning, the engine rotation speed is calculated using the output value of the output shaft rotation sensor, and if both the turbine rotation sensor and the output shaft rotation sensor are malfunctioning, the engine rotation speed is calculated at the maximum NE. Set values (steps 142-147).

When determining the engine rotation speed from the other rotation sensors mentioned above, the following conversion formula is used.

Engine speed NB = NOX shift stage gear ratio (at lock-up off) = NO
× Shift stage gear ratio (at lock-up off and NO ≧ 200 Orpm) = NO × Shift stage gear ratio When off and NO≦100Orp10 0Orp shift stage gear ratio (when lock-up is on) = NT
X shift gear ratio (NT ≧ 200 Orpm at lock-up off) = NTX Shift gear ratio
Shift stage gear ratio X1.03 (at lock-up off and NTslooorpm) In this way, when each rotation sensor fails, the rotation speed is converted based on the output value of the other rotation sensor and used for control.

〔Effect of the invention〕

As described above, according to the present invention, when each rotation sensor fails, the rotation speed is estimated by converting values obtained from other rotation sensors. Therefore, although an accurate rotation speed cannot be obtained, an estimated value that does not interfere with control can be obtained. Therefore, even if the rotation sensor fails,
It will not lead to serious accidents. Furthermore, since a spare rotation sensor is not required, it can be manufactured at low cost.

Furthermore, when all the rotation sensors are out of order, the rotation speed is set to the highest value. At this time, the gear is set to the highest gear, so there is less shock in the event of a breakdown while the vehicle is running.

[Brief explanation of the drawing]

FIG. 1 shows an automatic transmission of an electronically controlled automatic transmission which is an embodiment of the present invention. FIG. 2 shows a hydraulic circuit for driving the automatic transmission of FIG. FIG. 3 shows an electronic control circuit that controls the hydraulic circuit of FIG. FIG. 4 is a flowchart of the main routine of the CPU of the electronic control circuit of FIG. 3, a vehicle speed sensor interrupt, a turbine rotation sensor interrupt, an engine rotation sensor interrupt, and a scheduled interrupt. FIG. 5 is a flowchart of a rotational speed calculation processing routine of the CPU of the electronic control circuit of FIG. CPU...Central processing unit, 20...Battery, 21...Ignition switch, 22...Constant voltage power supply, 23...Engine rotation sensor 24...Turbine rotation sensor 25...Output shaft rotation Sensor 26... Throttle sensor 27... Neutral start switch, 31...
Overdrive cut switch, 32...Idle switch, 33...41...42...43...44...45...46...B, 47...48...B2...C2...B1... CO... BO... C1... 600/601/605/606°Brake switch, clutch COtlIL? Solenoid valve for 111, solenoid valve for clutch 02 control, solenoid valve for brake B1 control, solenoid valve for brake B1 control, solenoid valve for brake B2 control, solenoid valve for low and reverse inhibition solenoid valve for lock-up control, line pressure control Solenoid valve, 1st and Rev brake, direct clutch, second brake, OD clutch, OD brake, forward clutch, ・Turbine shaft, ・OD planetary gear, ・Output shaft, 16...1 way clutch, 607...over Drive mechanism, 608... Gear transmission mechanism, 609.617, 618... Carrier, 610.61
9.621... Planetary pinion, 611... Input shaft, 612... Sun gear, 613... Housing, 614... Intermediate shaft, 615... Sun gear shaft, 701... Oil sump, 702 ... Hydraulic pump, 703 ... Pressure adjustment valve, 704 ... Line pressure oil path, 705.706, 707, 708.709 ... Manual valve, 710 ... Valve, 711 ... Shift valve , 712...Lockup control valve.

Claims (2)

[Claims] (1) An electronically controlled automatic transmission comprising an automatic transmission and an electronic control means for controlling the automatic transmission, an engine rotation speed detector that measures the rotation speed of the input shaft of the automatic transmission, and a turbine rotation of the automatic transmission. a turbine rotation speed detector that measures the rotation speed of the shaft; an output shaft rotation speed detector that measures the rotation speed of the output shaft of the automatic transmission; a first system that estimates the engine rotation speed from the turbine rotation speed;
engine rotation speed estimating means; second engine rotation speed estimating means for estimating engine rotation speed from the output shaft rotation speed; first engine rotation speed estimating means for estimating turbine rotation speed from the engine rotation speed.
Turbine rotation speed estimation means; second turbine rotation speed estimation means for estimating the turbine rotation speed from the output shaft rotation speed; first output shaft rotation speed estimation means for estimating the output shaft rotation speed from the engine rotation speed; second output shaft rotation speed estimating means for estimating the output shaft rotation speed from a number; first engine rotation speed detector failure determination means for determining a failure of the engine rotation speed detector using the turbine rotation speed; a second engine rotation speed detector failure determination means for determining failure of the engine rotation speed detector using a number; and a first turbine rotation speed detector failure determination means for determining failure of the turbine rotation speed detector using the engine rotation speed. determining means; second turbine rotation speed detector failure determination means for determining failure of the turbine rotation speed detector using the output shaft rotation speed; determining failure of the output shaft rotation speed detector using the engine rotation speed; a first output shaft rotation speed detector failure determination means; a second output shaft rotation speed detector failure determination means for determining a failure of the output shaft rotation speed detector using the turbine rotation speed; and the first engine rotation speed detector. When the failure determination means detects a failure, the second engine rotation speed estimating means is actuated; when the second engine rotation speed detector failure determination means detects a failure, the first engine rotation speed estimation means is actuated; When the rotation speed detector failure determination means detects a failure, the second turbine rotation speed estimation means is activated, and when the second turbine rotation speed detector failure determination means detects a failure, the first turbine rotation speed estimation means is activated, Said first
When the output shaft rotation speed detector failure determination means detects a failure, the second output shaft rotation speed estimation means is activated, and when the second output shaft rotation speed detector failure determination means detects a failure, the second output shaft rotation speed estimation means is activated. A fail-safe device for an electronically controlled automatic transmission, comprising: a control means for actuating the means. (2) Claim (1) further comprises: engine rotation speed setting means for setting the engine rotation speed to the maximum value; turbine rotation speed setting means for setting the turbine rotation speed to the maximum value; and output shaft rotation speed to the maximum value. output shaft rotation speed setting means for setting the output shaft rotation speed; the control means operates the engine rotation speed setting means when both the first and second engine rotation speed detector failure determination means detect a failure; When the second turbine rotation speed detector failure determination means both detect a failure, the turbine rotation speed setting means is activated, and the first and second turbine rotation speed detectors operate the turbine rotation speed setting means.
A fail-safe device for an electronically controlled automatic transmission, wherein when both an output shaft rotation speed detector and a failure determination means detect a failure, the output shaft rotation speed setting means is activated.