JPH02163565A - Control of automatic transmission for vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary of the Invention] This invention relates to a method for controlling an automatic transmission of a vehicle, particularly for controlling upshifts and downshifts of an automatic transmission when climbing and descending hills. and an accelerator pedal depression detection sensor that outputs a signal corresponding to the amount of pedal depression when the accelerator pedal is depressed, with the aim of improving gear shifting when descending slopes to enable smooth and expected driving. An automatic transmission for a vehicle is equipped with a vehicle speed sensor that outputs a signal corresponding to the vehicle speed, searches the output of these sensors for a shift map stored in the storage area of the control device, and changes the gear ratio based on the results. In the control method, a vehicle body tilt angle sensor is provided to detect the vehicle body tilt angle, and the vehicle body tilt angle based on a detection signal of the vehicle body tilt angle sensor is determined to increase the engine load to enable smooth uphill running. When the correspondingly set vehicle body tilt angle is exceeded, shift-up of the automatic transmission is prohibited without following the shift control by the gear shift knob, and the vehicle body tilt angle based on the detection signal of the vehicle body tilt angle sensor is smoothed. When the vehicle exceeds a vehicle body inclination angle set in response to an engine braking effect that enables smooth downhill driving, the shift amplifier of the automatic transmission is prohibited and downshift is allowed without following the shift control based on the shift map. .

[Industrial application field]

The present invention relates to a method for controlling an automatic transmission of a vehicle, and particularly to control of upshifts and downshifts of an automatic transmission when climbing and descending hills.

Automatic transmissions automatically change gear ratios based on vehicle speed and how much the accelerator pedal is pressed. For this purpose, for example, a map is used, and the value Z of the map is determined when the vehicle speed is X and the accelerator pedal is y, and the gear ratio is set to Z (shifts up/down).

[Conventional technology]

FIG. 3 shows an example of a speed change map. The horizontal axis is the vehicle speed, and the vertical axis is the amount of depression of the accelerator pedal, and the two-dimensional space defined by these is divided into three regions ■■■ by curves C+ and C2. The curve C1 defines the boundary for downshifting, and when the vehicle crosses this curve from the right to the left, the second gear is automatically changed to the first gear (low gear). In addition, curve C2 defines the boundary of upshifting,
When crossing this curve from the left to the right, the first speed is automatically changed to the second speed.

In other words, the gear position is maintained in the first gear in the region (2), the second gear in the region (2), and the current gear position in the region (3).

Although FIG. 3 shows only two speeds, first speed and second speed, there are many types of forklifts that have two speeds each for forward and reverse speeds. Cars often have 4 to 5 forward gears and 1 reverse gear.

[Problem to be solved by the invention]

However, when shifting gears using this shift map, there are problems when climbing and descending hills.

In other words, when the vehicle is driving uphill, if the shift map is followed, when the automatic transmission is in the first gear position, there will be enough torque and the vehicle speed will increase, and the vehicle will shift up to second gear, but When the speed increases, there is a lack of torque and the vehicle speed decreases, and when the road is flat, it would be in region ■, but it returns to region ■ and shifts down to 1st gear (1st gear - 2nd gear, 2nd gear - (1st gear is repeated), or the vehicle speed decreases during upshifting and returns to 1st gear without entering 2nd gear, which worsens the driving feeling when climbing hills. In some cases, the vehicle becomes unable to climb hills.

In addition, when the vehicle is driving downhill and follows the above-mentioned shift map, when the automatic transmission is in the first gear position and the accelerator pedal is released in anticipation of engine braking effect, the vehicle enters the region ■ (as indicated by arrow A). ) Shifts up to 2nd gear and engine braking becomes ineffective. If the engine brake does not work, the vehicle will accelerate because it is going downhill, and you will be forced to brake using the foot brake. In other words, when going downhill, even if you release the accelerator pedal and try to apply engine braking, the result will be unexpected, resulting in a problem that the driving feeling will deteriorate and, in some cases, the vehicle will be unable to brake.

The present invention aims to improve these points and improve the gear shifting when climbing and descending slopes in vehicles using automatic transmissions, thereby enabling smooth and expected driving. .

[Means for Solving the Problems] In the present invention, a vehicle body inclination angle sensor 30 is provided in a vehicle 35 as shown in FIG. 2, and the upshift/downshift is controlled by the output of this sensor as shown in FIG. 1. .

That is, if the vehicle body inclination angle detected by the sensor 30 is greater than or equal to the set value SD for a downhill slope, the shift amplifier to the low gear is downshifted and the shift amplifier to the high gear is prohibited. Further, if the vehicle body inclination angle is less than the set value S[, J- for uphill slopes, the shift amplifier is prohibited.

The vehicle body inclination angle setting value SU for two slopes is set in accordance with the upper limit load of the engine that enables smooth uphill running (for example, 15 %). In addition, the vehicle body inclination angle setting value SD for downhill slopes is set in accordance with the engine braking effect that enables smooth downhill driving even when shifting or uphill (set to a slope angle that does not require engine braking). ).

(Function) According to this automatic transmission control method, when the slope angle of the vehicle body exceeds the upper limit slope slope angle SU when driving uphill, control is performed to prohibit upshifting of the automatic transmission. does not repeat upshifts and downshifts.Furthermore, when driving downhill, if the tilt angle of the vehicle body exceeds the lower limit downhill tilt angle SD, the soft amplifier is prohibited and downshifts are allowed, so the vehicle does not have engine play as before. This way, the vehicle can go uphill and downhill smoothly.

[Example] Figure 2 shows an example in which the present invention is applied to a forklift,
35 is the forklift, 19 is its driving wheel, and 36 is a fork that moves up and down.

The engine 10 of this vehicle includes a wet single-plate clutch 11,
Drive wheels 19 via automatic transmission 14 and differential gear mechanism 18
to drive. Connecting the engine 10 and automatic transmission 14/
The connection and disconnection (degree of connection) of the wet single-plate clutch 11 to be disconnected is adjusted by a rod 12a operated by a clutch control actuator 12. The clutch control actuator 12 is driven by a drive current output from the flank actuator drive circuit 13 in response to a command signal from the central processing unit 20, and performs the clutch control described above.

The automatic transmission 14 is shifted up or down by a shift I actuator 15, which is driven by a shift actuator drive circuit 16 that produces an output in accordance with command signals from the central processing unit 20.

Although not shown, the engine 10 is also used as a power source for a hydraulic pump that supplies hydraulic oil to a shift cylinder that raises and lowers the fork 36 and a tilt cylinder that tilts the mast.

The depression amount detection sensor 25 of the accelerator pedal 24 is equipped with a potentiometer and is connected to the accelerator pedal 2 provided at the driver's seat.
This analog voltage is converted into a digital signal by the A/D converter 26 and taken into the central processing unit 20 via the interface 23.

The vehicle body inclination angle sensor 30 is horizontally attached to the vehicle body of a forklift 35. This is the pendulum and its position (angle of inclination)
It is equipped with a magnetoresistive element that detects the angle of inclination of the vehicle body, and outputs a voltage that indicates the angle of inclination of the vehicle body. During operation, there is vibration and the effects of acceleration and deceleration, but these are removed through signal processing. The above voltage indicating the vehicle body inclination angle is converted into a digital signal by the A/D converter 31, and also taken into the central processing unit 20 via the interface 23.

A vehicle speed sensor 17 that generates pulses corresponding to the rotation of the automatic transmission 14 is provided on the output shaft of the automatic transmission 14, and the output pulses are also taken into the central processing unit 20 via the interface 23.

Central processing unit 2, which forms the core of the control system of this automatic transmission
0 is equipped with a continuous read only memory (ROM) 22 and a random access memory (RAM) 21, and operates according to the control program stored in the ROM 22 and the above-mentioned speed change map. The vehicle speed, vehicle body inclination angle, etc. are stored in the RAM 21.

The ROM 22 also stores a hill climbing inclination angle setting value SU that is set corresponding to a vehicle body inclination angle at which the vehicle climbs a hill smoothly.
A downhill inclination angle set value SD is stored, which is set corresponding to the engine braking effect that allows the vehicle to run smoothly downhill.

When shifting the automatic transmission 14 to a shift amplifier or downshift, the central processing unit 20 outputs a shift drive signal corresponding to upshift or downshift to the shift actuator drive circuit 16. The drive circuit 16, which receives a drive signal from the central processing unit 20, supplies a drive current corresponding to upshift or downshift to the shift actuator 15, thereby causing the automatic transmission 14 to shift up or down. When upshifting or downshifting the automatic transmission [14], it is necessary to temporarily disengage the clutch 11, so the central processing bag W20 outputs a clutch disengagement response signal to the clutch control actuator drive circuit 13.

Next, the operation of the apparatus shown in FIG. 2 will be explained according to the flowchart shown in FIG. As shown in the automatic transmission control flowchart in FIG. 1, the central processing unit receives the tilt angle detection signal output from the vehicle body tilt angle sensor, calculates the vehicle body tilt angle based on the tilt angle detection signal, and then Determine whether the slope angle is larger or smaller than the set value of the slope slope ■.

As a result of this determination, if the inclination angle of the vehicle body is larger than the inclination setting value SU, the central processing unit will cause the shift actuator drive circuit 16 to perform a shift drive even if it is in the shift-up region on the shift map. The current gear position of the automatic transmission 14 is continued (2) without outputting a signal, and the process proceeds to the next step (2).

On the other hand, if it is determined that the vehicle body tilt angle based on the tilt angle detection signal output from the vehicle body tilt angle sensor is smaller than the tilt angle setting value SU, the system performs upshift and downshift control according to the shift map. , the central processing unit searches the shift map based on the detection signal from the accelerator pedal depression amount detection sensor 25 and the detection signal from the vehicle speed sensor 17, and determines whether the area on the shift map is an upshift area or a downshift area. ■ To judge. As a result of this determination, if it is determined that the shift-up region is present, the central processing unit outputs a shift-up drive signal to the shift actuator drive circuit 16. The drive circuit 16 energizes the shift actuator 15 with a drive current corresponding to an upshift, thereby causing the automatic transmission 14 to shift up, that is, to a high gear.

In addition, if the central processing unit searches the shift map in step (2) and determines that it is not in the shift-up region as a result of the determination in step (2), or in step (2),
The central processing unit searches the shift map based on the detection signal from the accelerator pedal depression amount detection sensor 25 and the detection signal from the vehicle speed sensor 17, and determines in step (2) whether or not the area on the shift map is for downshifting. make judgments. As a result of the determination in step (2), if it is determined that the area on the shift map is a downshift area, the central processing unit outputs a shift drive signal corresponding to downshift to the shift actuator drive circuit 16 in step (2). The shift actuator 15 is driven to downshift the automatic transmission 14 to a low gear.

As described above, when the tilt angle of the vehicle body exceeds the tilt angle setting value, that is, when the tilt angle of the vehicle body is greater than the upper limit tilt angle, the central processing unit prohibits the upshift control, thereby causing the automatic transmission to shift. It avoids repeated upshifts and downshifts and allows the vehicle to climb hills smoothly.

Further, if the vehicle body inclination angle based on the output signal of the inclination angle sensor is larger than the downhill inclination angle set value SD, the central processing unit transmits the information to the shift actuator drive circuit 17 without searching the shift map. If the gear is currently in low gear, it will prohibit upshifting, and if it is in high gear, it will output a signal to support downshifting.■

(Effects of the Invention) As described above, according to the present invention, a vehicle body tilt angle sensor is provided to detect the tilt angle of the vehicle body in order to detect the tilt angle of the slope,
When the tilt angle of the vehicle body based on the detection signal of the vehicle body tilt angle sensor is larger than the preset upper limit tilt angle, the automatic transmission is prohibited from shifting up. The automatic transmission eliminates the need for repeated upshifts and downshifts, which improves the driving feel and enables smooth uphill driving. In addition, when driving a vehicle downhill, if the vehicle body tilt angle based on the detection signal of the vehicle body tilt angle sensor is greater than the preset lower limit tilt angle, the automatic transmission will shift to a high gear even if the accelerator pedal is released. Therefore, braking by engine braking is not disabled, and smooth downhill running is possible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is an explanatory diagram showing an embodiment of the present invention, and FIG. 3 is an explanatory diagram of a speed change map. In FIG. 2, 24 is an accelerator pedal, 25 is an accelerator pedal depression detection sensor, 17 is a vehicle speed sensor, 14 is an automatic transmission, 20 is a control device, and 30 is a vehicle body tilt angle sensor.

Claims (1)

[Claims] 1. The control device (20) includes an accelerator pedal depression amount detection sensor (25) that outputs a signal corresponding to the amount of depression of the accelerator pedal and a vehicle speed sensor (17) that outputs a signal corresponding to the vehicle speed. A vehicle body tilt angle sensor (30) that detects a vehicle body tilt angle in a vehicle automatic transmission control method in which a shift map stored in a storage area is searched using the outputs of these sensors and the gear ratio is changed based on the result. is provided, and the vehicle body tilt angle based on the detection signal of the vehicle body tilt angle sensor is
When the vehicle body tilt angle (SU), which is set in accordance with the upper limit load of the engine that enables smooth hill climbing, is exceeded, the automatic transmission is prohibited from shifting up without following the shift control based on the shift map, and the vehicle body The vehicle body tilt angle (SD) is set based on the detection signal of the tilt angle sensor to correspond to the engine braking effect that enables smooth downhill driving.
1. A method for controlling an automatic gear ratio of a vehicle, characterized in that when the gear ratio exceeds the gear ratio, an upshift of the automatic transmission is prohibited and a downshift is allowed without following the shift control based on the shift map.