JPH04300462A - Transmission control method for automatic transmission - Google Patents

Abstract

PURPOSE:To protect an automatic transmission in case that a rotational difference between left and right wheels is increased to be a specified value or more through slipping at the time of starting on a low mu road, by preventing shifting up of the automatic transmission, and thereby preventing abrupt increasing of differential operational rotation. CONSTITUTION:In case of operation controlling of a vehicle by means of an ECU, a transmission rage is judged by means of a transmission stage computation means 4 to which signals are input from an engine throttle opening detecting means 2 and an output rotational speed detecting means 3. When a shift position is in a D range or a 2 range, next, right and left driving shaft rotational number reading is carried out by means of left and right driving shaft rotational detecting means 7, 6. It is judged whether a difference between rotations of the left and right driving shafts is within a regulated range or not. When the answer is No, shifting up to be caused by transmission solenoids S1, S2 is prevented by means of a transmission preventing means 10 in the ECU.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for an automatic transmission, and more particularly to a shift control method when a rotation difference occurs between left and right wheels.

0002

2. Description of the Related Art FIG. 4 shows a conventional speed change control device for an automatic transmission, which is described in Japanese Patent Publication No. 63-63782. The engagement of the elements is as shown in Table 1.

0003

[Table 1] The shift control of this automatic transmission is shown in Table 1.
As you can see, this is done by turning on and off the solenoids S1 and S2, and the turning on and off of the solenoids S1 and S2 is based on commands from the electronic control unit (hereinafter referred to as ECU) based on signals such as vehicle speed and engine throttle opening. carried out by

0004

[Problem to be solved by the invention] When a vehicle starts on a low μ road such as a snowy or icy road, the left and right wheels have different coefficients of friction with the road surface, causing one wheel to slip. , E
The value of the apparent vehicle speed detected by the CU increases rapidly.

In such a case, in the conventional shift control method as described above, the solenoids S1 and S2 are switched based on this apparent vehicle speed value to perform an upshift, and the slip rotation becomes larger and larger. It turns out.

[0006] Therefore, the relative rotation between the pinion gear and pinion shaft of the differential device located between the left and right wheels becomes extremely large with respect to the engine rotation speed (for example, from 1 to 2).
In the case of an upshift, the relative rotation is approximately 1.8 times), so the pinion gear may seize.

The present invention has been made in order to eliminate the drawbacks of the conventional automatic transmission control method. That is, it is an object of the present invention to provide a shift control method for an automatic transmission that can protect the automatic transmission even when a large rotational difference occurs between left and right wheels.

[0008]

[Means for Accomplishing the Object] In order to achieve the above object, the present invention provides a shift control device for an automatic transmission in which an electronic control device performs shift control by switching solenoids of a hydraulic control circuit based on vehicle speed. The right drive shaft rotation detection means and the left drive shaft rotation detection means detect the rotation speeds of the right wheel and the left wheel, and based on this, the left and right rotation speed ratio calculation means calculates the rotation speed ratio of the right wheel and the left wheel. When this rotational speed ratio is equal to or higher than a set rotational ratio, the shift blocking means blocks upshift control by switching a solenoid of the electronic control device.

[0009]

[Operation] When starting on a low μ road such as a snowy road, if the rotation speed ratio of the right wheel and left wheel exceeds the set rotation ratio due to the difference in slip ratio between the left and right wheels, upshift switching of the solenoid is blocked. This prevents the rotational speed ratio from increasing. Therefore, upshift control of the automatic transmission due to an increase in apparent speed due to wheel slip is prevented, thereby suppressing a sudden increase in differential rotation.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in more detail below based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing a control system of a shift control method according to the present invention. The detection signals a to c are input to the gear position calculation means 4 of the ECU,
The calculation result d in the gear position calculation means 4 is inputted to the solenoid switching means 5.

Further, a rotation detection signal e from a right drive shaft rotation detection means 6 consisting of a right rotation sensor 21 attached to the right drive shaft 20 of the vehicle shown in FIG.
and a left drive shaft rotation detection means 7 consisting of a left rotation sensor 23 attached to the left drive shaft 22.
The rotation detection signal f is input to the left and right rotation speed ratio calculation means 8 of the ECU. Further, the calculation result g from the left/right rotation speed ratio calculation means 8 is input to the set rotation ratio determination means 9, this determination result h is input to the shift prevention means 10, and the transmission prevention signal i from this shift prevention means 10 is inputted to the set rotation ratio determination means 9. is input to the solenoid switching means 5. Shift control is performed by outputting a switching signal j from the solenoid switching means 5 to the solenoids S1 and S2 of the hydraulic control circuit.

In FIG. 2, 24 is an engine, 25 is a gear train of an automatic transmission, 26 is a differential device, 27R is a right wheel, and 27L is a left wheel.

Next, a three-speed ATM using the above-mentioned speed change control system
The speed change control method will be explained based on the flowchart shown in FIG.

In FIG. 3, the shift position detection means 1 reads the shift position (a), then the engine throttle opening detection means 2 reads the throttle opening (b), and the output rotational speed detection means 3 reads the vehicle speed. is read (c), and the gear shift range is determined by the gear position calculating means 4 (d).

[0016] Also, reading the shift position (a)
Based on this, decide whether to use D range or 2 range (e)
, D range or 2 range, next the right and left drive shaft rotation speeds are read (F) and (G) by the right drive shaft rotation detection means 6 and the left drive shaft rotation detection means 7, and the right and left drive shaft rotation speeds are read (F) and (G). It is determined whether the rotational difference between the left drive shafts 20 and 22 is within a specified range (H). If the rotation difference exceeds the specified range in this judgment (H), a first speed fixed signal is output (R).
.

In determining whether or not the first speed fixing signal is input, if there is an input, it is fixed to the first speed range (ru), and if there is no input, it is determined according to the throttle opening and vehicle speed. To set the shift range (e), switch the solenoid of the hydraulic control circuit according to the setting of each shift range (wa).

[0018] The above explanation is a method for controlling the speed change of a 3-speed ATM, but the same method can be used to control the speed change of a 4-speed or higher ATM.

[0019]

As described above, according to the present invention, upshifting of the automatic transmission is prevented when the rotation difference between the left and right wheels becomes larger than a predetermined value due to slip, such as when starting on a low μ road. By doing so, a sudden increase in differential rotation can be suppressed and the automatic transmission can be protected.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a control system showing an embodiment of a speed change control method according to the present invention;

FIG. 2 is an explanatory diagram showing drive shaft rotation detection means in the same embodiment;

FIG. 3 is a flowchart showing the speed change control method of the embodiment;

FIG. 4 is a circuit diagram showing a hydraulic control circuit of a conventional automatic transmission.

[Explanation of symbols]

6...Right drive shaft rotation detection means 7...Left drive shaft rotation detection means 8...Left and right rotation speed ratio calculation means 9...Setting rotation ratio determination means 10...Speed change prevention means S1, S2...Solenoid

Claims (1)

[Claims] Claim 1. A shift control device for an automatic transmission in which an electronic control device performs shift control by switching a solenoid in a hydraulic control circuit based on vehicle speed, wherein a right drive shaft rotation detection means and a left drive shaft rotation detection means are used to detect right drive shaft rotation. The rotational speeds of the wheels and the left wheel are detected, and based on this, the left and right rotational speed ratio calculation means calculates the rotational speed ratio of the right wheel and the left wheel, and when this rotational speed ratio is equal to or higher than the set rotational ratio,
A method for controlling a shift in an automatic transmission, characterized in that a shift inhibiting means inhibits upshift control by switching a solenoid of the electronic control device.