JPH1130319A - Control device for automatic transmission and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the running with a proper speed, even on the road with an up grade gradient or down grade gradient, by providing a speed cgange controller for changing a speed change ratio based on the order from a speed change ratio change order unit. SOLUTION: A road gradient calculation part 14 calculates the road gradient from the output signal of a road gradient detection sensor 1 and judges whether or not a car speed and gradient are caught to the visishift areas by giving them to the visishift area map of the most proper speed change ratio judging means 13. When they are entered to the visishift area, as the speed change ratio is not proper, the speed change ratio change order means 15 issues a speed change ratio change order. A speed change controller 16 receives this speed change ratio change order and changes the usual speed change ratio read out from the speed change map of the speed change ratio calculation part 3 and drives a solenoid drive circuit 12. As the visishift area is recognized as the function of the car speed and gradient, the evasion control can be carried out by discriminated the area much finely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic transmission control device for an automobile, and more particularly to an automatic transmission suitable for use in an automobile which recognizes a gradient of a road and switches control characteristics to characteristics suitable for the slope. The present invention relates to a control device and a control method.

[0002]

2. Description of the Related Art Conventionally, an automatic transmission for a vehicle is controlled on the assumption that the vehicle is traveling on level ground, and the vehicle is controlled with the same shift control characteristics even on an uphill, so that a phenomenon called a busy shift occurs and comfort is generated. There is an inconvenience that it is not possible to drive easily. That is, in the busy shift, at a certain gradient, the condition that the third speed is excessively accelerated at the third speed, but the driving force is insufficient at the fourth speed and the speed is reduced, so that when the vehicle tries to run at a constant speed, it frequently occurs. This is a phenomenon in which upshifts and downshifts are repeated. In such a case, if the shift to the fourth speed is prohibited, even if the accelerator pedal is returned to the extent that the vehicle does not accelerate, the vehicle can travel in the third speed without upshifting. Shift, that is, a switch (OD
The driver operates the cancel switch) to avoid a busy shift.

[0003] However, such an operation is troublesome, and some drivers do not know when to use the OD cancel switch. As a result, fuel economy may be deteriorated.

In view of this, control means for automatically inhibiting the shift to the fourth speed so as to prevent a busy shift by detecting a road gradient has been proposed. For example, Japanese Patent Publication No. Sho 61-15301 and There is a technique described in JP-B-61-48020.

[0005]

In the prior art, the gradient is calculated by a gradient sensor or the load of an engine, and the overdrive is prohibited when the gradient is such that a busy shift is likely to occur. Therefore, there is a region in which overdrive is prohibited even though a busy shift does not actually occur, and there is a disadvantage that fuel efficiency is deteriorated due to unnecessary restrictions.

On the other hand, on a downhill, it is preferable to control the speed while switching the gear ratio in accordance with the gradient to apply an appropriate engine brake. When heated, in extreme cases, there is a dangerous situation in which the brake is not effective due to the vapor lock of the driving fluid. Again, in this case,
A method has been proposed in which a gradient is detected and control is performed so as to automatically apply an engine brake.
There are techniques such as 140617, JP-A-3-9166 and the like.

However, in the above-described method, the gradient is calculated by a gradient sensor or the load of the engine, and when the engine brake reaches a required gradient, the range is forcibly set to two ranges or one range. , The engine speed becomes too high and the noise increases,
There is a disadvantage that the fuel cut region is narrowed due to the engine speed being too low and fuel efficiency is deteriorated.

The present invention has been made in view of such a problem, and an object of the present invention is to maintain a traveling operation at an optimum speed even on a sloped road such as an uphill or downhill. Another object of the present invention is to provide a control device and a control method for an automatic transmission, which have good fuel economy of the engine.

[0009]

In order to achieve the above object,
An automatic transmission control device and control method according to the present invention are directed to an automatic transmission control device for an automobile including an engine and an automatic transmission that changes the output of the engine and transmits the output to drive wheels.
A speed ratio calculating unit for calculating a speed ratio of the automatic transmission, a road gradient calculating unit for calculating a road gradient, and determining whether a change in the speed ratio is necessary based on a vehicle speed and the road gradient, A gear ratio change command unit that issues a command to change the gear ratio when a change is necessary; and a gear shift control unit that changes the gear ratio based on a command from the gear ratio change command unit. And

In a preferred specific embodiment of the automatic transmission control device according to the present invention, the transmission ratio change command unit stores data representing a busy shift region or data representing a shift diagram in an engine braking region. It is characterized in that it is determined whether or not the change of the gear ratio is necessary based on the road gradient calculation unit, and the road gradient calculation unit outputs the road gradient based on the output signal from the road gradient detection sensor or the driving torque and the vehicle speed. It is characterized by calculating.

The automatic transmission control device and control method according to the present invention configured as described above calculate an area where a busy shift occurs, and recognizes that the vehicle has approached the busy shift area using the calculated road gradient. In order to prevent a busy shift by changing the gear ratio,
Using the calculated road gradient and the vehicle speed, a gear ratio for obtaining an optimal engine brake is calculated, and an appropriate braking force can be obtained by changing the gear ratio.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an automatic transmission control apparatus for an automobile according to the present invention.

FIG. 1 shows the overall structure of a shift control system for an automatic transmission having a road gradient detection sensor. The transmission is controlled in accordance with an output signal of a road gradient detection sensor 1 for detecting a physical inclination angle of a vehicle. This is to change the shift line read from the shift map 3a in the control device 2. The automatic transmission 4 of the vehicle transmits the driving force to the tires 6 by changing the output of the engine 5. By operating a solenoid valve 8 provided in a hydraulic circuit 7, the automatic transmission 4 in the transmission 4 is illustrated. The shift is performed by switching the clutch that does not operate.

The shift control device 2 is configured as a control device using a microcomputer. The CPU 9 receives the vehicle speed detected by the vehicle speed detection unit 10 and the throttle opening detected by the throttle detection unit 11. And ROM
A speed ratio suitable for the vehicle speed is obtained by reading out a speed ratio corresponding to the vehicle speed and the throttle opening from the speed change map 3a stored in the storage device 3a, and the solenoid drive circuit 12 sends the solenoid valve 8 to the solenoid valve 8 in accordance with the obtained speed ratio. To send current,
The gear ratio is changed by switching the clutch. That is, the shift map 3a functions as a speed ratio calculating unit, and the solenoid drive circuit 12 functions as an output interface of a shift control unit. The RAM is a memory temporarily used for performing calculations in the course of these controls.

The gradient detecting section (sensor) 1 detects the inclination angle of the vehicle with respect to the horizon. For detecting the inclination angle, for example, one that shows an absolute azimuth like a gyroscope,
Use a vertical or horizontal direction such as a weight or level. The inclination angle output from the road gradient detection sensor 1 is input to the CPU 9 to calculate the gradient of the road. The speed ratio read from the speed change map 3a is changed based on the road gradient obtained in this way, so that the speed change control characteristics facilitate driving.

FIG. 2 illustrates a shift control characteristic called a busy shift improved by the present embodiment. FIG. 2A shows the state of 3 stored in the shift map 3a.
FIG. 2B shows the driving force of the third speed and the fourth speed of the vehicle. The shift line in FIG.
By transcribing to (b), a shift curve like a thick line is obtained. From this, the torque at the time of gear shifting can be read, so that the relationship between the torque before and after gear shifting and the running resistance shows the range in which the busy shift occurs.

For example, an uphill slope of 10 [%]
When driving at a constant speed at km / h, the throttle opening 4
When the vehicle accelerates at 0 degrees, the speed exceeds 100 km / h. Therefore, when the accelerator is returned at the point A, the vehicle crosses the shift line at the point B and shifts up. At the 4th speed, the operating point shifts to the C point. However, the torque decelerates to the D point, and the accelerator is naturally depressed. As a result, the gear is shifted down to the 3rd speed again at the E point, and Repeat returning to the point and accelerating. If the throttle opening is 22 degrees at the third speed, the balance is equilibrated at a gradient of 10%. However, according to this shift line, if the throttle opening is 22 degrees, the upshift occurs before 90 km / h, so that an equilibrium state cannot be realized.

That is, 82 to 161 [km /
h], the region sandwiched between the up line and the down line is a region where the equilibrium state where the third speed drive torque line and the traveling resistance line cross cannot be realized. When a vehicle speed range where a busy shift can occur is cut out for each gradient, a busy shift area shown in FIG. 2C is obtained. To avoid a busy shift, when approaching this area, the 3 → 4 shift line may be shifted to a higher speed side, or the shift may be prohibited and the area may disappear.

Therefore, as shown in FIG. 1, a busy shift area map 13a is provided in the ROM in the shift control device 2, and it is determined whether or not the vehicle enters the busy shift area according to the vehicle speed and the gradient. If it is determined that the above occurs, the gear ratio is changed.

The busy shift region is determined by the shift line and the driving force characteristics. Since the driving force characteristics are determined by the engine characteristics and the torque converter characteristics, the busy shift region is uniquely determined by the vehicle. Therefore, the busy shift area may be calculated in advance and stored in the ROM. The road gradient calculator 14 in the control block of FIG.
The road gradient is calculated from the output signal of the road gradient detection sensor 1, the vehicle speed and the gradient are given to the busy shift area map 13a of the optimum gear ratio determination means 13 to determine whether or not the vehicle enters the busy shift area. If it does, the gear ratio is not optimal, so the gear ratio change command means 15 generates a gear ratio change command. In response to the gear ratio change command, the gear change control unit 16 changes the normal gear ratio read from the gear map 3a of the gear ratio calculation unit 3 to change the normal gear ratio.
2 is driven.

According to the present embodiment, unlike the prior art, where the avoidance control is performed by judging the busy shift area only from the gradient, the busy shift area is recognized as a function of the vehicle speed and the gradient. The avoidance control can be performed by identifying.

For this reason, for example, in the example of FIG. 2C, the avoidance control is conventionally performed uniformly at a gradient of 6% or more, whereas the avoidance control is performed at 8% or more at 100 km / h. In other words, upshifting is allowed between 6 and 8% of 100 km / h, so that driving with good driving feeling and fuel economy can be performed.

FIG. 4 is a control block diagram showing a second embodiment of the present invention. The structure of the transmission control device 2 is the same as that of FIG. 3, but the difference from FIG. The point is that no angle detection sensor is used. That is, instead of detecting the road gradient itself, it is obtained by calculation from the driving torque. The specific means for calculating the drive torque in the drive torque calculation unit 17 is described in detail in Japanese Patent Application Laid-Open No. Hei 6-317242 filed by the applicant of the present invention.・ Transmission input rotation speed Nt (turbine rotation speed of torque converter)
The drive torque can be calculated from a signal such as the throttle opening TVO. The flat-land running resistance characteristic map 18 of the vehicle is stored in advance in the ROM, and the flat-land running resistance TRL is read out according to the vehicle speed and subtracted from the driving torque.

Further, the acceleration a is obtained by differentiating the vehicle speed, the acceleration torque Ta is calculated by multiplying the vehicle weight M by the tire radius r, and the gradient resistance torque TRg is obtained by further subtracting the acceleration torque Ta. Dividing by gives the slope. Such a gradient calculating means is described in JP-A-6-74320 filed by the applicant of the present invention. In this manner, the gradient and the vehicle speed calculated without using the tilt sensor are stored in the busy shift area map 13a.
, And when it is determined that the vehicle has entered the busy shift region, the speed ratio change command means 15 sends a speed ratio change command to the speed change control unit 16. The transmission control unit 16 changes the transmission ratio read from the transmission map 3a and sends it to the solenoid drive circuit 12.

According to the present embodiment, the busy shift avoidance control can be performed without using the tilt sensor, so that the function can be realized with a low-cost control system.

FIGS. 5 and 7 show a third embodiment of the present invention. The difference from FIGS. 1 and 3 is that an engine brake area shift diagram 19a is used instead of the busy shift area map 13a. Is to have.

On a downhill, the engine brake operates with the throttle opening being 0, but the braking force varies depending on the speed ratio at that time as shown in FIG. 6 (a). It is a point where the intersection with the running resistance curve at each gradient balances, and it is possible to balance the vehicle speed and go down the hill. However, when the equilibrium point is shown by a graph of the vehicle speed and the gradient, as shown in FIG. Become. That is, the line A represents the vehicle speed balanced by the first speed engine brake for each gradient, and the line B represents the vehicle speed balanced by the second speed engine brake. The area at the upper left of the line A cannot be realized unless the foot brake is used together. An equilibrium state can be realized between the A-line and the B-line by slightly opening the throttle at the first speed.

Similarly, the lines C and D represent the vehicle speed balanced by the third and fourth speed engine brakes, and the balance between the lines can be realized by adjusting the throttle opening. E
The line represents the vehicle speed in a state where the engine brake is not applied, that is, the vehicle speed balanced only by the aerodynamic resistance and the rolling friction. The region to the lower right of this line cannot be realized unless a positive driving torque is applied. Between the lines, for example, between the lines C and D, the control cannot be performed unless the speed is 3rd speed, and the control can be performed by opening the throttle at 1st speed or 2nd speed.

However, since the engine speed becomes too high at the first speed, it is preferable to apply the engine brake at the third speed. Therefore, if FIG. 6B is stored as the shift diagram 19a in the engine brake area,
The engine brake can be applied at the optimal gear ratio. According to the method of the present embodiment, it is possible to perform driving with good driving sensation and fuel efficiency without causing an uncomfortable feeling because the engine speed is too high, and conversely without narrowing the fuel cut region because it is too low. it can.

Although the three embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and does not depart from the spirit of the present invention described in the appended claims. Various changes can be made in the design.

For example, although the third embodiment has been described as detecting the gradient, it is needless to say that the gradient may be obtained by calculation as in the second embodiment.

Also, in order to avoid confusion, the first and second embodiments show only the busy shift avoidance control, and the third embodiment shows only the engine brake control. Needless to say, the system may be provided with both control and engine brake control.

[0033]

As can be understood from the above description, the automatic transmission control device and the control method for an automobile according to the present invention can select an optimum speed ratio according to the vehicle speed and the gradient, thereby avoiding a busy shift, The engine brake can be applied at the optimum gear ratio, so that drivability can be improved and running characteristics with good fuel efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a control system according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a busy shift region of FIG. 1;

FIG. 3 is a control block diagram of FIG. 1;

FIG. 4 is a control block diagram according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a control system according to a third embodiment of the present invention.

FIG. 6 is a characteristic diagram showing an engine braking region according to a third embodiment of the present invention.

FIG. 7 is a control block diagram of FIG. 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Road gradient detection sensor, 2 ... Shift control device, 3 ... Gear ratio calculation part, 3a ... Shift map, 5 ... Engine, 7 ... Hydraulic circuit, 9 ... CPU, 12 ... Solenoid drive circuit, 13 ...
Optimal gear ratio discriminating means, 13a: busy shift area map, 14: road gradient calculating unit, 15: gear ratio change instructing means, 16: gear shift control unit.

Claims (10)

[Claims] An automatic transmission control device for an automobile, comprising an engine and an automatic transmission for shifting the output of the engine and transmitting the output to drive wheels, wherein a gear ratio calculating unit for calculating a gear ratio of the automatic transmission. A road gradient calculating unit for calculating a road gradient; determining whether or not the speed ratio needs to be changed based on a vehicle speed and the road gradient; and issuing a command to change the speed ratio when a change is required. An automatic transmission control device, comprising: a speed ratio change command unit that changes the speed ratio based on a command from the speed ratio change command unit. 2. The apparatus according to claim 1, wherein said gear ratio change command means determines whether or not said gear ratio needs to be changed based on data representing a busy shift area stored in advance.
3. The automatic transmission control device according to claim 1. 3. The gear ratio change command means determines whether or not the gear ratio needs to be changed based on data representing a gear shift diagram in an engine brake area stored in advance. 3. The automatic transmission control device according to claim 1. 4. The automatic transmission control device according to claim 1, wherein said road gradient calculating section calculates a road gradient based on an output signal from a road gradient detecting sensor. 5. The automatic transmission control device according to claim 1, wherein said road gradient calculating section calculates a road gradient based on a driving torque and a vehicle speed. 6. A method for controlling an automatic transmission of an automobile having an engine and an automatic transmission for shifting the output of the engine and transmitting the output to driving wheels, wherein a speed ratio of the automatic transmission is calculated to calculate a road gradient. Calculating, based on the vehicle speed and the road gradient, determining whether or not the gear ratio needs to be changed, and if so, issuing a command to change the gear ratio, and changing the gear ratio. Characteristic automatic transmission control method. 7. The automatic transmission control method according to claim 6, wherein whether the gear ratio needs to be changed is determined based on data representing a busy shift area stored in advance. 8. The automatic transmission according to claim 6, wherein whether the gear ratio needs to be changed or not is determined based on data representing a gear shift diagram in an engine brake area stored in advance. Control method. 9. The automatic transmission control method according to claim 6, wherein said road gradient is calculated based on an output signal from a road gradient detection sensor. 10. The automatic transmission control method according to claim 6, wherein said road gradient is calculated based on a driving torque and a vehicle speed.