JP3286419B2 - Shift control method for vehicle with automatic transmission - Google Patents

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 a vehicle equipped with an automatic transmission, and more particularly, to reduce the load on a tire having a reduced air pressure when the vehicle is running with a reduced tire pressure on any of the wheels. Transmission control method for the vehicle.

[0002]

2. Description of the Related Art Since it is not preferable to run a vehicle with the air pressure of tires of a vehicle lowered more than a certain level, various tire pressure alarm devices (tire pressure judgment devices) have been proposed. For example, an air pressure sensor that detects a tire air pressure of a wheel, and detects a tire air pressure by an air pressure sensor including a transmission unit attached to the wheel side and a reception unit provided on the vehicle body side, and detects any one of the wheels. 2. Description of the Related Art Tire air pressure alarm devices that output an alarm when the air pressure drops are in practical use. On the other hand, when tire pressure drops,
Since the number of rotations of the wheel with reduced air pressure increases, 4
There have been proposed, for example, ones provided with wheel speed sensors for detecting the wheel speeds of the wheels, and determining a decrease in tire air pressure based on the wheel speeds detected by the wheel speed sensors.

For example, Japanese Patent Application Laid-Open No. Sho 63-305011 discloses that the output of a wheel speed sensor of four wheels is used to calculate the sum of the wheel speeds of a pair of wheels on a diagonal line and the sum of the wheel speeds on another diagonal line. When the difference from the sum of the wheel speeds of a certain pair of wheels is equal to or greater than a predetermined value, it is determined that the air pressure of any one of the pair of wheels having the larger total wheel speed has decreased, and When the larger one of the wheel speeds of the wheels is larger than the average value of the wheel speeds of the four wheels by a predetermined value or more, it is determined that the air pressure of the wheel has decreased, and the determination result is warned. A configured tire pressure warning device is described.

[0004]

Conventionally, there has not been proposed any shift control for an automatic transmission in a case where the tire air pressure of any of the wheels has decreased. When shifting up or down the automatic transmission as in the case where the air pressure is normal, the load on the tire with reduced air pressure is not reduced at all, the damage to the tire progresses, and the reliability decreases. There is. In particular, since the load on the tire is high during sudden acceleration or sudden deceleration, it is desirable to limit sudden acceleration / deceleration when the tire air pressure decreases. SUMMARY OF THE INVENTION An object of the present invention is to provide a shift control method capable of reducing a load on a tire when a tire pressure decreases.

[0005]

According to a first aspect of the present invention, there is provided a shift control method for a vehicle having an automatic transmission, the shift control in a vehicle including an automatic transmission and a tire pressure determining unit for detecting a decrease in tire pressure of a wheel. The method is characterized in that when a decrease in tire air pressure is detected by the tire air pressure judging means , the automatic transmission is controlled so as to start at the second speed when starting .

[0006] Shift control of a vehicle with an automatic transmission according to claim 2
The method is to detect automatic transmissions and a decrease in tire pressure at the wheels.
In a vehicle provided with a tire pressure determination means for
Speed control method, wherein the tire pressure determination means
When a decrease in tire pressure is detected, the throttle
The shift down mechanism applied when the rate of change
Shift applied when the rate of change is less than a predetermined value.
It is set to be harder to kick down than the down map
It is characterized by having.

[0007]

In the shift control method for a vehicle with an automatic transmission according to the first aspect of the present invention, when the tire pressure determination means detects a decrease in the tire pressure, the tire pressure is reduced when the vehicle starts moving.
Since the automatic transmission is controlled so as to start quickly , the load on the tire is reduced, the damage to the tire with reduced air pressure is suppressed, and the reliability of the tire can be prevented from lowering.

[0008] Shift control of a vehicle with an automatic transmission according to claim 2
The method comprises the steps of:
When a decrease in air pressure is detected, the rate of change in throttle opening
The shift down map to be applied when
The shift down map applied when the rate of change is less than the specified value
Because it is set to be harder to kick down than the
When the rate of change of the throttle opening is suddenly accelerated beyond a predetermined value,
The tire load is reduced,
You.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an embodiment in which the shift control method of the present invention is applied to a shift control device of a riding rear-wheel drive type automobile equipped with an automatic transmission and a tire pressure determination device. As shown in FIG. 1, the left and right front wheels 1 and 2 are driven wheels, left and right rear wheels 3 and 4 are driving wheels, and the output torque of an engine 5 is transmitted from an automatic transmission 6 to a propeller shaft 7. It is configured to be transmitted to the left and right rear wheels 3 and 4 via a driving device 8 and left and right drive shafts 9 and 10.
The automatic transmission 6 has a lock-up clutch with four forward speeds and one reverse speed.

A throttle valve 11 is provided in an intake system of the engine 5, and the throttle valve 11 is mechanically linked to an accelerator pedal (not shown). A control unit 20 that controls the automatic transmission 6 and that also functions as a control device of the tire pressure determination device is provided. Four wheels 1, 2, 2, and 3 as sensors and switches for tire pressure determination control
Wheel speed sensors 21, 22, 2 for detecting wheel speeds of 3, 4
3, 24, an initial setting switch 25 for instructing an initial value setting in the tire pressure determination control, a warning lamp 26 which is turned on when a decrease in tire air pressure is detected, a steering angle sensor 27 for detecting a steering angle of a steering wheel. Etc. are provided.

As sensors and switches for controlling the automatic transmission 6, a throttle opening sensor 28 for detecting the opening of the throttle valve 11, a vehicle speed sensor 29, a brake switch 30 which is turned on when the brake pedal 12 is depressed,
In addition, general sensors such as an oil temperature sensor are provided. The detection signals from the sensors and switches are supplied to the control unit 20 and the warning lamp 2
6 is driven and controlled by the control unit 20.

The control unit 20 includes a microcomputer for controlling tire pressure determination, a microcomputer for controlling gear shifting for controlling the automatic transmission 6, and A / D conversion of other general analog detection signals. A / D converter, a circuit for shaping the pulse signals from the wheel speed sensors 21 to 24, an input / output interface,
It is composed of a plurality of drive circuits and the like. Further, the microcomputer for controlling tire pressure determination of the control unit 20 stores a control program for controlling tire pressure determination, which will be described later. The map is stored.

Next, the tire pressure determination control will be described. The tire pressure determination control includes an initial value setting process shown in FIG. 2 and a tire pressure determination process shown in FIG. First, an initial value setting process for obtaining an initial value of a determination variable will be described. This initial value setting process starts the use of a car, replaces a tire of any wheel, or adjusts a tire pressure. Is performed in a state where the tire pressures of the four wheels are in a normal state, and is started by operating the initial setting switch 25. In the flowchart, reference symbol Si (i = 10, 1
1,...) Indicate each step.

In FIG. 2, first, it is determined whether or not the initialization switch 25 is ON.
At 11, various signals (the steering angle signal θh, the vehicle speed signal V, the wheel speed signals Pw1 to Pw4, etc.) are read. Next, S12
In, it is determined whether the vehicle is traveling straight and the road surface is a high μ road (high friction road surface) and is a good road with little unevenness. When the determination is Yes, the process proceeds to S13. However, whether or not the vehicle is traveling normally can be determined from the vehicle speed V, and whether or not the vehicle is traveling straight can be determined from the steering angle θh.
Based on the w1 to Pw4 and the vehicle speed V, it can be determined from the slip ratio of the drive wheels 3 and 4.
It can be determined from the degree of variation in wheel speed using w4.

Next, when the determination in S12 is Yes, the wheel speed signals Pw1 to Pw4 for 400 rotations of the wheels are read (S12).
13) Then, the wheel speeds Vw1, Vw2, Vw3, V
w4 is calculated (S14). Then, using these wheel speeds, in S15, the initial value D0 of the determination variable is calculated by the calculation formula shown in FIG. Ends. In the arithmetic expression of S15, the sum of the wheel speeds of the wheels 1 and 4 in a diagonal relationship is used to calculate
Since the sum of the three wheel speeds is subtracted, when the tire pressures of the four wheels are in the same normal state, the initial value D0 of the determination variable becomes substantially equal to zero.

Next, a description will be given, with reference to FIG. 3, of a tire pressure determination process which is constantly executed while the vehicle is running. First, S11 to S1 in the initial value setting process
Similarly to S4, S20 to S23 are executed, and in S24, the determination variable D is calculated by the illustrated calculation formula (the same calculation formula as the calculation formula in S15), and then in S25, (D−
It is determined whether or not the absolute value of D0) is equal to or greater than a predetermined value Δ. If the determination is No, the tire pressure is determined to be normal in S26 and the routine returns.
In the case of s, it is determined in S27 that the tire pressure of any of the wheels has decreased, and the warning lamp 26 is turned on for a predetermined time (for example, 5 seconds) to notify the driver, and then the process returns.

In addition, as a supplementary explanation, for example, when the tire pressure of the left front wheel 1 decreases, the moving radius of the tire decreases, so that the wheel speed Vw1 increases, and the judgment variable D increases. When the tire pressure of the right front wheel 2 decreases, the wheel speed Vw2 increases and the determination variable D
Becomes smaller and the same phenomenon occurs in the rear wheels 3 and 4. Therefore, by comparing the absolute value of (D-D0) with the predetermined value Δ, it is possible to determine a decrease in tire air pressure.

Next, the shift control executed on the automatic transmission 6 by the control unit 20 will be described. First, the shift map shown in FIG. 4 will be described. This shift map is a reference shift map similar to a general shift map in which upshifting and downshifting are set (excluding lines a, b, and c). And line a,
and a sub shift map composed of b and c. Line a of the sub-shift map sets a downshift line from the second speed to the first speed.
The line is shifted to a lower speed than the downshift line from the first gear to the first gear, and the line a is used to regulate kickdown.
The top part of is set as an inclined line.

Line b in the sub-shift map is 3rd speed → 2
The shift down line to the high speed is set, but it is shifted to a lower speed side than the shift down line from the third speed to the second speed in the reference shift map, and the top of the line b to regulate the kick down. The part is set as an inclined line. Line c in the sub-shift map sets a downshift line from 4th gear to 3rd gear, but is shifted to a lower speed side than the downshift line from 4th gear to 3rd gear in the reference shift map. The top of the line c is set as an inclined line in order to restrict kickdown.

Next, shift control for controlling the automatic transmission 6 will be described with reference to FIG. When the control is started upon turning on the ignition switch, first, various signals (throttle opening degree θth, vehicle speed V, brake switch signal, signal of flag Fa, etc.) are read (S40), and then the flag Fa is set to 1 Is determined, that is, whether or not any tire pressure is decreasing (S41).
If the answer is No, in S42, the shift control based on the reference shift map is executed, and then the routine returns.

If the tire pressure is low, S
The process proceeds to 43, and it is determined in S43 whether or not the vehicle has started. When the vehicle speed V changes from 0 to positive, it is determined that the vehicle has started. In the case of starting, in S44, it is determined whether or not the rate of change dθth / dt of the throttle opening θth is equal to or greater than a predetermined value A. If the determination is Yes, the automatic transmission is started in S45 to start the second speed. A drive signal for shifting the sixth gear to the second gear is output to the corresponding solenoid valve of the control valve unit of the automatic transmission 6, and then returns. When the determination in S44 is No, the process shifts to S42 and shift control for starting the first speed normally is executed.

When the determination in S43 is No, in S46, the brake switch signal or the throttle opening θth
It is determined whether or not the vehicle is decelerating, and if the determination is Yes, that is, if the vehicle is in a decelerating state, in S47, the shift control based on the sub-shift map is executed, and thereafter, the routine returns. S
If the determination at No. 46 is No, it is determined at S48 whether or not the vehicle is accelerating based on the throttle opening θth.
In other words, when the vehicle is accelerating, it is determined in step S49 whether or not the rate of change dθth / dt of the throttle opening θth is equal to or greater than a predetermined value B. If the determination is Yes, the process proceeds to step S49.
At 50, shift-up shift control based on the reference shift map or shift-down shift control based on the sub-shift map is executed, and then the process returns. If the judgment in S48 is No
And when the determination in S49 is No, S42
Then, the shift control based on the reference shift map is executed.

The operation of the shift control described above will be described. When the tire pressure of the wheel is normal, the automatic transmission 6 is controlled based on the reference shift map, similarly to the normal shift control.
Is controlled. However, when the tire air pressure of any of the wheels is decreasing, the load on the tire can be reduced by performing the shift control as described below. When the vehicle is suddenly started, the vehicle is controlled to start at the second speed, so that the load on the tire is reduced, and the tire whose air pressure has been reduced can be prevented from being damaged, and the reliability can be prevented from being reduced. Further, at the time of deceleration, the downshift is performed using the sub-shift map. However, since the sub-shift map has a characteristic of shifting down on a lower speed side than the reference shift map, it becomes difficult to operate the engine brake,
The load on the tire can be reduced.

Further, also during acceleration, in a rapid acceleration state, shift-up shift control based on the reference shift map or shift-down shift control based on the auxiliary shift map is executed, so that the load on the tires is reduced as in the case of deceleration. be able to. In particular, since the auxiliary shift map is set to a characteristic that suppresses kickdown, it is difficult to switch to a low gear where tire load increases.

In the above embodiment, the wheel speed sensors 21 to 21 are used.
Although the case where the tire air pressure judging device that judges the decrease of the tire air pressure using the wheel speed signal from 24 is applied has been described as an example, the tire air pressure judging device is not limited to the above-described embodiment, The present invention is similarly applicable to a case where a tire pressure determination device configured to detect a decrease in tire pressure by using detection signals from four pressure sensors that respectively detect the pressures of four tires is also applied. is there.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a shift control device of an automobile having an automatic transmission and a tire pressure determination device according to an embodiment.

FIG. 2 is a flowchart of an initial value setting process of tire pressure determination control in the tire pressure determination device of FIG. 1;

FIG. 3 is a flowchart of a tire pressure determination process of tire pressure determination control in the tire pressure determination device of FIG. 1;

FIG. 4 is a diagram of a shift map of the shift control device of FIG. 1;

FIG. 5 is a flowchart of shift control of the shift control device of FIG. 1;

[Explanation of symbols]

 1, 2 front wheels 3, 4 rear wheels 6 automatic transmission 20 control unit 21-24 wheel speed sensor 25 initial setting switch 26 warning lamp 27 steering angle sensor 28 throttle opening sensor 29 vehicle speed sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16H 61/00-61/64 B60C 23/00-23/08 B60K 31/00 F16H 59/50

Claims (2)

(57) [Claims] 1. A shift control method for a vehicle, comprising: an automatic transmission; and a tire pressure determining means for detecting a decrease in tire pressure of a wheel, wherein the tire pressure determining means detects a decrease in tire pressure. When starting, it will automatically start at 2nd speed
Shift control method of an automatic transmission with the vehicle and controlling the transmission. 2. An automatic transmission and a low tire pressure of a wheel.
Vehicle equipped with tire pressure determination means for detecting
A shift control method, wherein the tire pressure determining means reduces the tire pressure.
Is detected, the rate of change of the throttle opening is greater than or equal to a predetermined value.
The shift down map applied at the time of
The key is lower than the shift down map applied when the
Is characterized by being set to be difficult to
Shift control method for vehicle with dynamic transmission.