JPH09196954A - Vehicle speed calculation device for electronic type automatic speed change gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the control stability by weighted average correction so as to increase weight of wheel speed in the last time compared with that in this time, for updating the wheel speed in the last time, when the wheel speed in this time is in a low vehicle speed area. SOLUTION: The pulse signals are inputted from wheel speed sensors 5A-5D to an ABS-ECU 6, and it calculates the number of rotation of each wheel for finding each wheel speed. And, speeds of both the front wheels and the rear wheels are calculated. The speeds of both the front wheel and rear wheel transmitted from the ABS-ECU 6 are received by a vehicle speed calculation device 2A of an ECT-ECU 2, and a specified weighted average correction is applied to these received speeds of both the wheels. By this weighted average correction, a calculation value of the wheel speed is stabilized in a low vehicle speed area, and control stability of speed changing control and center differential clutch control (4WD driving control) to backlash is improved. Further, since the area of looseness can be considered at acceleration and deceleration, stability of control is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed calculation device used in an electronic automatic transmission, and particularly, there is a fluctuation in the detected speed of a wheel speed sensor in a low vehicle speed range, a failure of the wheel speed sensor, and the like. Also relates to a vehicle speed calculation device capable of ensuring control stability of an electronic automatic transmission.

[0002]

2. Description of the Related Art Conventionally, an electronic automatic transmission converts a vehicle speed and an accelerator pedal depression amount into an electric signal, and uses the vehicle speed and the accelerator pedal depression amount as parameters to determine an optimum gear ratio suitable for a traveling state. Making a choice. Regarding the vehicle speed information, in a vehicle speed calculation device used for an electronic automatic transmission, an output signal of a wheel speed sensor, which is attached to a wheel and is composed of, for example, an electromagnetic pickup (MPU), is input, and the vehicle speed is calculated. Is required.

[0003]

By the way, in the vehicle speed calculating device for the electronic automatic transmission, there is a great influence on the fluctuation of the vehicle speed in the low vehicle speed region due to the rattling on the mounting of the wheel speed sensor. This rattling is caused by the rattling caused by vibrations in the positional relationship between the rotor and the pickup constituting the electromagnetic pickup and the connection of the connector. Due to the vehicle speed fluctuation in the low vehicle speed range, there is a problem that the control system of the electronic automatic transmission responds, for example, from 1st speed to 2nd speed or vice versa, and becomes unstable. In the case of high speed, since the vehicle speed value is large, the fluctuation of the vehicle speed due to the rattling is small, so that there is no particular problem.

Further, in the low vehicle speed range, it is expected that the range of rattling in mounting the wheel speed sensor changes between deceleration (during braking) and acceleration. For example, the braking force is applied to the front wheels during deceleration, resulting in large rattling, and the driving force is applied to the rear wheels during acceleration, resulting in large rattling. Furthermore, when braking on a snowy road,
Communication line from the wheel speed sensor to the control device of the electronic automatic transmission when the ABS (anti-lock brake system) is switched from non-operation to operation or vice versa, when the wheel speed sensor fails during high-speed traveling At the time of disconnection, there is a problem that the value of the vehicle speed instantly becomes "0", and downshifting (1st speed) is performed. At this time, engine overrun may result in engine or transmission abnormality.

Therefore, in view of the above problems, the present invention can secure the stability of the control system against the fluctuation of the vehicle speed due to the rattling of the mounting of the wheel speed sensor in the low vehicle speed range, and at the time of braking lock or the like. It is an object of the present invention to provide a vehicle speed calculation device for an electronic automatic transmission that can avoid downshifts caused by the above.

[0006]

In order to solve the above-mentioned problems, the present invention relates to a vehicle speed calculating device for an electronic automatic transmission for obtaining the wheel speed of a vehicle, when updating the wheel speed. If the wheel speed obtained this time is in a low vehicle speed region, the wheel speed is smoothed so that the weight of the previous wheel speed becomes larger than the current wheel speed, and the previous wheel speed is corrected. Update speed. By this means, the calculation of the wheel speed is stable in the low vehicle speed region without being affected by rattling, and the control stability of the shift control and the center differential clutch control (4WD drive control) can be improved.

When determining whether or not the wheel speed obtained this time is in the low vehicle speed range, different low vehicle speed ranges are set during acceleration and deceleration. By this means, the wheel speed calculation is further stabilized in consideration of the difference in the rattling region during acceleration and deceleration. When the difference between the wheel speeds of this time and the previous time is larger than the predetermined value for hold determination, the wheel speed value of this time is held without being updated for the hold time. By this means, it is possible to prevent downshifting at the time of switching between the operation and non-operation of the braking lock and anti-lock brake systems and when the wheel speed sensor has a failure.

The predetermined value for hold determination and the hold time are used as a function of the wheel speed, and the predetermined value for hold determination and the hold time are calculated by linear interpolation with respect to the current wheel speed. This is because the predetermined value for the hold determination is set to be small in the low vehicle speed range and is large in the high vehicle speed range so as to take into consideration the normal state at higher speeds. Further, it is to take into account that it takes a short time to reach the wheel speed value to be upshifted at a low speed as a function of increasing the hold time in the low vehicle speed range and decreasing it in the high vehicle speed range. .

The predetermined value for the hold determination and the hold time are separately used for calculating the wheel speeds of the front wheels and the rear wheels. The vehicle speed pulse stop time when the brake is locked, when the anti-lock brake system is activated / deactivated, and when the wheel speed sensor fails may change depending on the load on the wheels, braking characteristics, etc. This is because it is necessary to set a predetermined value.

As the wheel speed, the one transmitted from the antilock brake system is used. This widens the range of application.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a vehicle speed calculation device for an electronic automatic transmission with an antilock brake system. As shown in the figure, a transmission 1 provided between an engine (E / G) of a vehicle and drive wheels has a hydraulic torque converter for transmitting the output of the engine and a gear ratio of three or four stages. It comprises a transmission and a hydraulic control circuit section for automatically controlling the gear ratio according to the vehicle speed and the depression amount of the accelerator pedal. A solenoid is incorporated in this hydraulic control circuit section, and is controlled by an ECT-ECU (electronic control unit) 2 for transmission. In addition, the fluid torque converter employs a lock-up clutch mechanism that mechanically directly connects the input shaft and the output shaft to 100% transmission efficiency. A solenoid is incorporated in this lock-up clutch mechanism. Cage,
It is controlled by the ECT-ECU 2.

A four-wheel drive (4W) is adopted in this vehicle, and for this reason, a center differential (C / D) clutch 3 for distributing the drive torque of the engine to the front and rear wheels is provided. A solenoid is incorporated in the center differential clutch 3 and is controlled by the ECT-ECU. Furthermore, the four wheels 4A, 4B (front left and right wheels), 4C of the vehicle
And 4D (left and right rear wheels), for example, wheel speed sensors 5A, 5B, 5C and 5D, which are electromagnetic pickups, for example.
Is attached.

An antilock brake system is adopted in this vehicle, and the ABS-ECU 6 is connected to the wheel speed sensors 5A, 5B, 5C and 5D. The ABS-ECU 6 controls the braking hydraulic pressure applied to the wheel cylinders of each vehicle at the time of vehicle braking, secures an appropriate cornering force to ensure steering performance, and minimizes the braking stop distance. The slip ratio is controlled in order to obtain the value. In order to control the slip ratio, the ABS-ECU 6 determines the wheel speed. Therefore, the ABS-ECU 6 inputs pulse signals from the wheel speed sensors 5A, 5B, 5C, and 5D, calculates the rotation speed of each wheel, and sets each wheel speed to SPDA, SPD.
Find B, SPDC and SPDD. And the front wheel speed FSPD
Is FSPD = (SPDA + SPDB) / 2, rear wheel speed RSPD is RS
Calculated as PD = (SPDC + SPDD) / 2.

Vehicle speed computing device 2A of ECT-ECU 2
Then, the front wheel speed FSPD transmitted from the ABS-ECU 6
And the rear wheel speed RSPD is received, and the following smoothing correction is added to the received front wheel speed FSPD and rear wheel speed RSPD. FIG. 2 is a flow chart for explaining the moderating correction of the front wheel speed FSPD in the vehicle speed calculation device 2A.

In step S1, it is determined whether the hold flag is ON. If this determination is "NO", the process proceeds to step S4. In addition, when the hold flag is ON, it means that the front wheel speed is not updated. If the hold flag is ON in step S2, it is determined whether or not the hold time has expired. This judgment is "NO"
Then, the process proceeds to step S4.

In step S3, the hold inhibition flag is turned on. This is for performing the moderation correction. In addition to this, it is confirmed that the hold flag is OFF. Step S4
In, the front wheel speed FSPDi is calculated. Here, i indicates the ordinal number of sampling. In the anti-lock brake system, the minimum wheel speed is 2 km / h,
When it is determined that the wheel speed sensor has failed, 0 km / h is output.

In step S5, it is determined whether or not the hold flag is ON, and if "YES", the process ends and the moderation correction process is not performed. In step S6, if the above determination is "NO" and the hall flag is OFF, the comparison between the current front wheel speed FSPDi and the previous front wheel speed FSPDi-1 is made as follows.

FSPDi ≧ FSPDi−1 If this determination is “YES” and acceleration is in progress, the process proceeds to step S12. In step S7, if the above determination is "NO" during deceleration, it is determined in the following manner whether the previous front wheel speed smoothing correction value FPSDSMi-1 is greater than a predetermined speed. It is judged whether FSPDSMi-1> 10 km / h is established.

If this determination is "YES", the process proceeds to step S12. In step S8, the above determination is "N
O ”, the correction value FSPDSM when decelerating and in the low vehicle speed range
When i-1 is smaller than the specified speed,
For example, 1/4 smoothing correction is performed. FSPDSMi = (FSPDi + 3FSPDi-1) / 4 The result of this smoothing correction is stored in the memory as an A value.

In step S9, it is determined whether the hold prohibition flag is ON. If "NO", the process proceeds to step S14. If the above determination is "YES" in step S10, the hold prohibition flag is turned off. In step S11, FPSPDMi is stored in the memory as the A value, and the front wheel speed is updated.

In step S12, if the determination in step S6 is "YES" and the vehicle is accelerating, it is determined as follows whether the previous front wheel speed smoothing correction value FSPDSMi-1 is greater than another predetermined speed. It is judged whether FSPDSMi-1> 12 km / h is established.

If this determination is "NO" and the vehicle is in the low vehicle speed region during acceleration, the process proceeds to step S8, and the moderation correction is performed. In step S13, the current front wheel speed FSPDi is stored in the memory when the vehicle speed is in the high vehicle speed range during deceleration and acceleration.
It is stored as a value and the process proceeds to step S9. That is, the smoothing correction is not performed.

In step S14, the A value is read from the memory and the following calculation is performed. B = | A-FSPDSMi-1 | In step S15, the front wheel vehicle speed FSPD of the smoothed correction
The relationship between SMi and the wheel speed hold determination value X is formed in advance. The wheel speed hold determination value X changes depending on the wheel speed. That is, the higher the speed, the larger the wheel speed hold determination value X. This is because the higher the vehicle speed, the more normal the vehicle speed. The wheel speed hold judgment value X is calculated by linear interpolation from the previous FSPDSMi-1.

In step S16, it is determined whether or not X≤B. If "NO", step S
Proceed to 11. In step S17, the above determination is "Y
In the case of "ES", the hold flag is turned on in the case of breaking lock, failure of the wheel speed sensor, switching of operation / non-operation by the antilock brake system, and the like.

In step S18, the relationship between the front wheel vehicle speed FPSDSMi and the wheel speed hold time Y for the smoothing correction is formed in advance. The wheel speed hold time Y changes depending on the wheel speed. That is, the wheel speed hold time Y is reduced as the speed increases. This is because it takes less time for the wheel speed value to be shifted up as the speed becomes lower.
The wheel speed hold time Y is calculated by linear interpolation from the previous FSPDSMi-1.

In this way, the wheel speed hold time Y in which the front wheel speed is not corrected is set in the hold timer, and the process is terminated. The vehicle speed calculation device 2
The moderation correction of the rear wheel speed RSPD at A is performed in the same manner. In the vehicle speed calculation device 2A, the vehicle speed V is calculated from the corrected front wheel speed FSPDSM and the rear wheel speed RSPDSM.
Is calculated as V = (FSPDSM + RSPDSM) / 2, and ECT-
It is used to control the transmission 1 via the ECU.

According to the present invention, the calculated value of the wheel speed becomes stable in the low vehicle speed region by the smoothing correction in step S8, and the shift control and the center differential clutch control (4WD drive control) are controlled against rattling. Improves stability. further,
Steps S7 and S12 make it possible to take into consideration the rattling region during acceleration and deceleration, so that the stability of control is improved.

Further, in steps S14 to S19, when the difference between the current and previous smoothing correction values is temporarily larger than the predetermined value, the braking control, the wheel speed sensor failure, the antilock braking are performed. When the operation / non-operation of the system is switched, abrupt downshift can be avoided by fixing the current smoothing correction value for a predetermined time. When the difference between the current and previous smoothing correction values becomes smaller than the predetermined value after the predetermined time has elapsed, the original operation is resumed.

Further, by independently setting the wheel speed hold determination value X and the wheel speed hold time Y for the front and rear wheels, when the brake is locked, when the antilock brake system is switched between active and inactive, and when the wheel speed sensor fails. It is possible to consider that the front and rear wheel speeds change due to the load on the wheels, braking characteristics, etc. during the vehicle speed pulse stop time due to.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a vehicle speed calculation device for an electronic automatic transmission with an antilock brake system.

FIG. 2 is a front wheel speed FSPD in the vehicle speed calculation device 2A.
It is a flow chart explaining the moderation correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transmission 2 ... ECT-ECU 2A ... Vehicle speed calculating device 5A, 5B, 5C, 5D ... Wheel speed sensor 6 ... ABS-ECU

Claims (6)

[Claims] 1. A vehicle speed calculation device for an electronic automatic transmission for determining a wheel speed of a vehicle, wherein when the wheel speed obtained this time is in a low vehicle speed range when updating the wheel speed, The vehicle speed of the electronic automatic transmission, characterized in that the previous wheel speed is updated by performing a rounding correction on the wheel speed so that the weight of the previous wheel speed becomes larger than the previous wheel speed. Arithmetic unit. 2. The low vehicle speed range that is different during acceleration and deceleration is set when determining whether or not the wheel speed calculated this time is in the low vehicle speed range. 1. A vehicle speed calculation device for an electronic automatic transmission according to 1. 3. When the difference between the wheel speeds at this time and the previous time is larger than a predetermined value for hold determination, the wheel speed value at this time is held at the previous wheel speed without being updated for a hold time. The vehicle speed calculation device for an electronic automatic transmission according to claim 1, wherein: 4. The predetermined value for hold determination and the hold time are functions of the wheel speed, and the predetermined value for hold determination and the hold time are calculated by linear interpolation with respect to the current wheel speed. The vehicle speed calculation device for an electronic automatic transmission according to claim 3. 5. The electronic automatic transmission according to claim 4, wherein the predetermined value for the hold determination and the hold time are separately used for calculating the wheel speeds of the front wheels and the rear wheels. Vehicle speed calculator. 6. The wheel speed used is that transmitted from an antilock brake system.
The vehicle speed calculation device for an electronic automatic transmission according to claim 1.