KR20000060174A - Shift control method of automatic transmission when vehicle speed sensor malfunctions - Google Patents

Abstract

PURPOSE: A shifting control method when a velocity sensing part of an automatic transmission is in a breakdown is provided to maintain 3-speed holding in case the shifting limit conditions more than the fixed number repeat and to change into 2-speed in case the slip of a torque convertor is more than a fixed value. CONSTITUTION: A shifting control method when a velocity sensing part of an automatic transmission is in a breakdown contains the following steps: a step to start time counting if shifting limit signal is output and to judge whether an input revolution number is more than a standard revolution number or not; a step to continuously output the shifting limit signal and to judge whether a standard time is exceeded, if the input revolution number is more than the standard revolution number; a step to output a duty control signal for holding 3-speed if the standard time is exceeded; a step to return to the step of the time counting if the standard time is not exceeded and to control 3-speed holding if a returning number is more than a fixed revolution number; a step to change into 2-speed when a fixed time is maintained in condition that a slip ratio of a torque convertor in 3-speed holding is more than a standard value and to output an error signal.

Description

SHIFT CONTROL METHOD OF AUTOMATIC TRANSMISSION WHEN VEHICLE SPEED SENSOR MALFUNCTIONS}

The present invention relates to a shift control method in the case of a vehicle speed detection unit failure of an automatic transmission for a vehicle, and more particularly, a value calculated by calculating a pulse signal output from a pulse generator-B, is detected as a vehicle speed. The present invention relates to a shift control method in case of a failure of a vehicle speed detecting unit of an automatic transmission to effectively perform a fail safe function.

For example, an automatic transmission applied to a vehicle may include a gear shift control of a target shift stage by controlling a plurality of solenoid valves to control hydraulic pressure according to a driving speed of a vehicle, an opening ratio of a throttle valve, and various vehicle driving conditions. The shift is made automatically.

In other words, when the driver converts the select lever to the desired shift stage, the manual valve port is changed and the hydraulic pressure supplied from the oil pump is selectively operated by operating various operating elements of the planetary gear set according to the duty control of the solenoid valve. Let this be done.

Looking at the operation path of the automatic transmission operated according to the principle of operation, when the rotational power of the engine is transmitted to the torque converter, the torque converter converts the rotational power into torque and inputs it to the planetary gear set.

Then, the planetary gear set has a power path for shifting and selectively driving the driving wheels according to the operation of the hydraulic control means according to the control of the shift control means to shift the driving wheels.

Such an automatic transmission having a power transmission path must be operated at the time of failure in order to prevent damage to driving stability due to the operation of the engine brake while the transmission is suddenly shifted to the low speed, that is, 1 and 2 speeds due to a failure in the high speed driving state. It provides a fail-safe function to shift gears into the inside.

In controlling the fail safe function as described above, the vehicle speed is a very important factor. In the related art, the vehicle speed was detected from a vehicle speed sensor disposed at a rear side of the differential.

However, the automatic transmission is provided with a pulse generator -B (PG-B) for detecting the rotational speed of the planetary gear set, and the frequency of the output pulse of the pulse generator -B is fixed at a constant ratio with the vehicle speed signal. There is no need to detect the vehicle speed from the vehicle speed sensor.

Accordingly, a control method that detects the vehicle speed from the pulse generator-B as a means of reducing costs by omitting unnecessary vehicle speed sensors and performing a fail safe function in the event of failure of the pulse generator-B is the Korean patent of the applicant. Application 97-80006 (97. 12. 31) has been proposed.

However, in the control method of the present invention, when an output signal is not generated intermittently from the pulse generator-B, it is not converted into a three-speed hold but also a failure signal is not output, thereby preventing a quick response to a transmission failure. By intermittently repeating the phenomenon in which the shift stage is fixed for a while, there is a problem that the automatic transmission is further damaged.

In a state where the vehicle is held at three speeds, when the vehicle travels uphill or overdrives, excessive slip occurs in the torque converter, thereby overheating, thereby damaging the automatic transmission.

Accordingly, the present invention has been invented to solve the above problems, and an object of the present invention is to detect a value calculated by calculating a pulse signal output from the pulse generator-B as a vehicle speed, and the failure of the pulse generator-B. Fail safe function can be performed, but if the shift prohibition condition is repeated above the standard value, it should be 3 speed hold state even if the shift prohibition establishment time is within a certain time. The present invention provides a shift control method in the case of a failure of a vehicle speed detection unit of an automatic transmission in which shifting to a vehicle is performed.

1 is a block diagram of a failure diagnosis apparatus of an automatic transmission for operating the present invention,

2 (A), (B) is an operation flowchart of a shift control method of an automatic transmission according to the present invention.

In order to realize the above object, the present invention provides a shift control method in the event of a vehicle speed detecting unit of an automatic transmission,

Decrease rate (ΔNo_max) in which the vehicle speed reduction rate (ΔNo) is limited in a state where the select lever position of the driving vehicle is located in the forward ranges (D, 3, 2, 1) and the shift is not made to the set target speed change stage. Determining whether to rise, but if it is determined to rise, determining whether the set shift prohibition condition is satisfied and outputting a shift prohibition signal when the shift prohibition condition is satisfied;

If the vehicle speed reduction rate ΔNo does not rise above the limited reduction rate ΔNo_max, it is determined whether the driving vehicle speed reduction rate ΔNo decreases by more than the limited reference vehicle speed reduction rate ΔNo_max_brake due to the brake operation. Determining whether the set shift prohibition condition is satisfied and outputting a shift prohibition signal when the shift prohibition condition is satisfied;

If the running vehicle speed reduction rate ΔNo does not decrease above the limited reference vehicle speed reduction rate ΔNo_max_brake by the brake operation, it is determined that there is no brake operation. In this state, the vehicle speed is detected and the engine speed Ne is stalled. (Stall) determining whether the speed is higher than the rotation speed, and when determined to be high, determining whether the set shift prohibition condition is satisfied, and outputting a shift prohibition signal when the shift prohibition condition is satisfied;

Shifting to a target shift stage according to the detected driving information if the vehicle speed is not detected without the brake operation and the engine speed Ne is determined to be equal to or smaller than the stall speed;

If the shift prohibition signal is input or the shift prohibition and the shift prohibition release signal are repeated more than a predetermined number of times, the gear is held at 3 speeds. The present invention provides a shift control method in the event of a failure of the vehicle speed detecting unit of an automatic transmission, the step of outputting a fault signal of the vehicle speed detecting means at the same time as the shift.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

1 is a block diagram of a failure diagnosis apparatus for operating the present invention. When the power transmission path of the automatic transmission for a vehicle is transmitted to the torque converter 4, the torque converter 4 is inputted by the torque converter 4. The torque is converted into torque and input to the planetary gear set 6.

Then, the planetary gear set 6 is shifted while selectively operating the element according to the driving of the hydraulic control means under the control of the shift control means 8 to drive the driving wheel 12 through the differential 10. Has a power path.

In the power transmission process, the shift control means 8 detects the degree of opening of the throttle valve whose opening and closing state is variable in conjunction with the operation state of the accelerator pedal, not shown, and outputs a corresponding signal to the throttle valve opening degree detection unit;

A vehicle speed detector for detecting a rotation speed of the vehicle and outputting a corresponding signal corresponding to the vehicle traveling speed;

A shift stage detection unit configured to detect a variable state of the shift stage and output a corresponding signal when the shift stage is changed according to the throttle valve opening amount and the vehicle speed;

Turbine shaft rotation speed detection unit for detecting the rotational speed of the turbine shaft of the torque converter connected to the input shaft of the transmission and outputs a corresponding signal,

An engine rotation speed detection unit configured to detect a rotation speed of the crankshaft which is varied according to an operating state of the engine and output a corresponding signal;

The shift control is performed by detecting a vehicle driving state from a shift lever detection unit that detects a position that is variable according to a driver's shift lever operation and outputs a corresponding signal.

In the shift control process as described above, the fail-safe control is performed as shown in FIG. 1, with the engine speed Ne, the input shaft speed Nt of the planetary gear set by the pulse generator-A (PG-A), and the pulse generator. -The hydraulic control unit 14 is controlled by judging the output signal of the output shaft rotational speed No of the planetary gear set by B (PG-B) from the shift control means 8 to be compared with the previously inputted program. The vehicle speed is transmitted to the speedometer of the cluster 16.

That is, in the shift control means 8, the vehicle speed reduction rate (ΔNo) of the traveling vehicle is greater than the limited reduction rate (ΔNo_max) when the shift range of the running vehicle is normal forward driving (D, 3, 2, 1 range). When decelerating,

When the running vehicle speed reduction rate ΔNo decreases by the brake operation above the limit reference vehicle speed reduction rate ΔNo_max_brake,

When the vehicle speed is not detected and the engine speed Ne becomes higher than the stall speed (1700 to 2500 RPM) in a state where the brake operation is not performed, the set speed change prohibition signal is output and the output shift is output. When the holding time of the prohibition signal passes the set reference time, it is determined that the pulse generator -B (PG-B) is broken and the shift stage is held at three speeds.

When the shift prohibition signal is repeated above the reference value, even if the shift prohibition time is within the set reference time, the speed is set to the third speed hold state, and the slip ratio of the torque converter 4 is set to the set reference value in the third speed hold state. If abnormal, the fail-safe control is carried out so that the shift to the second speed.

The fail safe control is performed in the same process as in FIG. 2 (A) and (B). First, in the shift control means 8, the position of the select lever of the vehicle in operation is forward driving ranges D, 3, 2, and the like. 1) it is determined whether or not (S100).

When the position of the select lever is determined as the forward driving range, the shift control means 8 determines whether the vehicle is shifting (S110), and if it is determined that the shift is in progress, moves to the main routine to perform the shift of the shift stage. Returns.

However, if it is determined that the vehicle is not shifted in the above, the deceleration of the output shaft rotation speed of the running vehicle is limited to some extent (except during tire slip), so that the reduction rate (ΔNo) is limited. No_max) or more is determined (S120).

If it is determined in step S120 that the driving vehicle speed reduction rate ΔNo has risen above the limited reduction rate ΔNo_max, the control means 20 determines whether the next shift prohibition condition is satisfied (S121).

Nt> β

The shift prohibition condition is that the select lever of the running vehicle is decelerated at the forward traveling range by the driving vehicle speed reduction rate (ΔNo) above the limited reference vehicle speed reduction ratio (ΔNo_max), and the rotation speed Nt of the turbine is the set reference value β. When it rises above, and this condition is satisfied, the shift control means 8 outputs a shift prohibition signal to the hydraulic control part 14 (S122).

Then, in the state where the shift prohibition signal is output as described above, the shift control means 8 starts the time count S200, and determines whether the input rotation speed Nt is greater than the set reference input rotation speed No x gear ratio + δ. It is determined (S200, S210).

Nt> No × gear ratio + δ (where Nt> a or No> b)

(In the above, a is the rotation speed of the set reference turbine and b is the set reference vehicle speed.)

If it is determined in the above that the input rotation speed Nt is larger than the set reference input rotation speed No x gear ratio + δ, the shift control means 8 sets the reference in the state of continuously maintaining the shift prohibition of S122. It is determined whether the time λ has elapsed (S220).

When it is determined in step S210 that the rotational speed Nt of the input shaft turbine is smaller than the set reference turbine rotational speed No x gear ratio + δ, it is determined whether the shift prohibition releasing condition is satisfied (S211).

The shift canceling condition satisfies the shift prohibition canceling condition if the absolute value calculated by subtracting the setting reference input rotation speed (No x gear ratio) from the input rotation speed Nt is smaller than the arbitrarily set determination reference value?. Judging by it.

When the shift prohibition releasing condition is satisfied in this way, the shift control means 8 releases the shift prohibition (S212), and performs a normal shift control according to the information detected during driving (S150).

However, if the shift prohibition release condition is not satisfied, the process returns to the time counting step S200 to continuously determine whether the shift prohibition condition is satisfied.

If it is determined that the reference time λ set in the step S220 has elapsed, the shift control means 8 determines that the vehicle speed detecting means, that is, the failure of the pulse generator-B (PG-B), makes the shift stage three speed. The duty control signal for holding is output to the hydraulic control unit 14 so that the speed change stage is held at three speeds (S230).

However, if the reference time (λ) set in the step S220 has not elapsed, the process returns to the time count step S200. In this case, the number of times of returning from the step S220 to the step S200 is detected and the number is four or more times. In operation S221, if it is four or more times, a duty control signal for holding at three speeds is outputted so that the shift stage is held at three speeds (S230).

In addition, the shift control unit 8 detects the slip ratio (1-Nt / Ne) of the torque converter 4 in the state of being held at the third speed stage in the step S230, and determines that the slip ratio is larger than the set reference value (η). If the slip ratio is greater than the set reference value (S240), it is determined whether the slip time (χ) is greater than the set reference time (t) (S250).

If the slip time (χ) in step S250 is greater than the set reference time, the shift control means 8 outputs a duty control signal for shifting to the second speed to the hydraulic control unit 14 to shift to the second speed (S260). At this time, the fault signal of the pulse generator-B (PG-B), which is a vehicle speed detecting means, is output (S270).

When the slip ratio 1-Nt / Ne is smaller than the set reference value η in step S240, a failure signal of the pulse generator-B (PG-B), which is a vehicle speed detecting means, is output (S270).

In addition, when the slip time χ is smaller than the set reference time t in step S250, the process returns to step S250.

If it is determined in step S120 that the traveling vehicle speed reduction rate ΔNo does not rise above the limited reference vehicle speed reduction rate ΔNo_max, the shift control means 8 determines that the driving vehicle speed reduction rate ΔNo is increased by the brake operation. It is determined whether the reduction is greater than the limited reference vehicle speed reduction rate ΔNo_max_brake (S130).

If it is determined in step S130 that the driving vehicle speed reduction rate ΔNo is reduced to the limit reference vehicle speed reduction rate ΔNo_max_brake by the brake operation, the shift control means 8 determines that the input rotation speed Nt is the set reference value β. After step S200 through the step S121 of determining whether a large shift is performed and the step S122 of the shift prohibition step, the shift prohibition is released if the shift prohibition release condition is satisfied in step S211 (S212). According to the information detected during driving, the normal shift control is performed to perform a target driving state (S150).

If it is determined in step S130 that the driving vehicle speed reduction ratio ΔNo is reduced to less than the limited reference vehicle speed reduction ratio ΔNo_max_brake by the brake operation, the shift control means 8 determines whether the brake switch is in an off state (S140). When the brake switch is in the on state, a normal shift control is performed according to the information detected during driving (S150).

If it is determined in step S140 that the brake switch is in the off state, it is determined whether the vehicle speed is detected (S141). If the vehicle speed is not detected, it is determined whether the engine speed is increased beyond the stall speed (S142). When the engine speed is determined to be higher than the stall speed, the step after the step S200 is executed through the shift prohibition step S143. In this case, when the shift prohibition release condition is satisfied in step S211, the shift prohibition is satisfied. In operation S212, a target shifting state is performed by performing normal shift control according to information detected during driving (S150).

In addition, when the vehicle speed is not detected in the step S141 or the engine speed is less than the engine stall speed in the step S142, a normal shift control is performed according to the information detected during driving (S150).

The embodiments of the present invention described above are not limited thereto, and those that can be easily implemented from the above embodiments are included in the present invention.

As described above, the present invention provides a vehicle speed detecting means when the set reference time λ has elapsed while satisfying only one shift prohibition condition among three shift prohibition conditions when the select lever of the driving vehicle is not shifting in the forward driving range. By determining that the failure of the vehicle is fixed at three speeds, it is possible to prevent inadvertent downshift shifting caused by the failure of the vehicle speed detecting means, thereby enabling safe driving.

In addition, since the output signal is not generated intermittently from the pulse generator-B, which is a vehicle speed detecting means, if the shift prohibition condition is repeated four or more times, the automatic transmission is further damaged by controlling in the three-speed hold mode. It can be prevented in advance.

In addition, when an excessive slip of the torque converter according to the case in which the vehicle is held in the third speed and traveling in an uphill state or in an overload state occurs, the shift control is performed in the second speed, thereby preventing overheating of the automatic transmission.

Claims (8)

In the shift control method when the vehicle speed detection unit of the automatic transmission breaks down, Decrease rate (ΔNo_max) in which the vehicle speed reduction rate (ΔNo) is limited in a state where the select lever position of the driving vehicle is located in the forward ranges (D, 3, 2, 1) and the shift is not made to the set target speed change stage. Determining whether to rise, but if it is determined to rise, determining whether the set shift prohibition condition is satisfied and outputting a shift prohibition signal when the shift prohibition condition is satisfied; If the vehicle speed reduction rate ΔNo does not rise above the limited reduction rate ΔNo_max, it is determined whether the driving vehicle speed reduction rate ΔNo decreases by more than the limited reference vehicle speed reduction rate ΔNo_max_brake due to the brake operation. Determining whether the set shift prohibition condition is satisfied and outputting a shift prohibition signal when the shift prohibition condition is satisfied; If the running vehicle speed reduction rate ΔNo does not decrease above the limited reference vehicle speed reduction rate ΔNo_max_brake by the brake operation, it is determined that there is no brake operation. In this state, the vehicle speed is detected and the engine speed Ne is stalled. (Stall) determining whether the speed is higher than the rotation speed, and when determined to be high, determining whether the set shift prohibition condition is satisfied, and outputting a shift prohibition signal when the shift prohibition condition is satisfied; Shifting to a target shift stage according to the detected driving information if the vehicle speed is not detected without the brake operation and the engine speed Ne is determined to be equal to or smaller than the stall speed; If the shift prohibition signal is input or the shift prohibition and the shift prohibition release signal are repeated more than a predetermined number of times, the gear is held at 3 speeds. Shifting the speed and outputting a fault signal of the vehicle speed detecting means; Shift control method when the vehicle speed detection unit failure of the automatic transmission. The method of claim 1, wherein the vehicle speed (No) detected according to the driving state of the automatic transmission comprising calculating the pulse value output by the pulse generator-B as the vehicle speed detecting means to detect the arithmetic value as the vehicle speed (No) Shift control method in case of vehicle speed detection unit failure. 2. The shift prohibition condition set when the driving vehicle speed reduction rate ΔNo is decelerated above the limited reduction rate ΔNo_max is set to the limited reference vehicle speed reduction rate ΔNo. No_max), and the shift control method when the vehicle speed detection part of the automatic transmission fails to determine that the shift prohibition condition is satisfied when it is detected that the input rotation speed Nt rises above the set reference value β. The speed change inhibiting condition when the running vehicle speed reduction rate ΔNo decreases by more than the limited reference vehicle speed reduction rate ΔNo_max_brake by brake braking is based on the driving vehicle speed reduction rate when the brake switch of the running vehicle is turned on. (ΔNo) is reduced above the limited reference vehicle speed reduction rate (ΔNo_max_brake), and when the input rotation speed (Nt) is detected as a value larger than the set reference value (β), the automatic transmission that determines that the shift prohibition condition is satisfied Shift control method in case of failure of vehicle speed detection unit. The method according to any one of claims 1 to 3, further comprising: starting a time count when the shift prohibition signal is output, and determining whether the input rotational speed Nt is greater than a set reference input rotational speed (No x gear ratio + δ); If it is determined that the input rotational speed Nt is greater than the set reference input rotational speed (No x gear ratio + δ), continuing to output the shift prohibition signal and determining whether the set reference time λ has elapsed; A third speed hold as an output of a duty control signal for holding the shift stage at three speeds when it is determined that the predetermined reference time λ has elapsed; Returning to a time count step if the reference time (λ) has not elapsed, and performing a third speed hold if the number of times of returning is equal to or greater than a predetermined number of times; Shifting to the second speed stage and outputting a fault signal when the slip ratio of the torque converter in the third speed hold state is maintained for a predetermined time or more in a state where the torque converter is equal to or greater than a predetermined reference value; Shift control method when the vehicle speed detection unit failure of the automatic transmission, characterized in that consisting of. The method of claim 5, further comprising: determining whether the shift prohibition releasing condition is satisfied when it is determined that the current input rotation speed Nt is smaller than the set reference input rotation speed No x gear ratio + δ; The shift control method when the vehicle speed detection unit failure of the automatic transmission comprising the step of performing a normal shift control in accordance with the driving information when the shift prohibition release condition is satisfied. The shift release condition is the above-mentioned when the absolute value calculated by subtracting the setting reference input rotation speed (No x gear ratio) from the input rotation speed Nt is smaller than the arbitrarily set determination reference value ε. A shift control method in the event of a vehicle speed detecting unit failure of the automatic transmission including determining that the shift prohibition releasing condition is satisfied. The shift control method according to claim 5, wherein the shift control signal is continuously output and the control is performed at three speeds after detecting the set reference time (λ) four or more times.