JPS636259A - Electronic control automatic transmission - Google Patents

Abstract

PURPOSE:To eliminate a shortage of driving force as well as to aim at smooth starting, by comparing the rotational frequency between an engine and an input shaft of a transmission and, when a speed difference in them exceeds the specified value, making the transmission shift down to a low speed step forcibly. CONSTITUTION:Various signals out of an engine output shaft speed sensor 04 and a transmission input shaft speed sensor 05 as well as various sensors 3, 01-03 and 07, and select switches S1-S4 are all inputted into an electronic controller 5, and on the basis of these signals, each of solenoid valves V1-V5 and a clutch actuator are controlled. In this case, each rotational frequency between an engine input shaft and a transmission input shaft is compared, and when a speed difference in them exceeds the specified value, a clutch slip is detected whereby a driving force shortage at the time of starting is judged. And, at the time of this judgment, each of shift and select actuators 1 and 2 is controlled, making them forcibly shift down to the optimum gear step.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronically controlled automatic transmission that performs control to an optimum gear position when a vehicle is started under a large load.

(Prior Art) Large vehicles such as buses and trucks, unlike passenger cars, are equipped with high-output engines in order to carry large amounts of cargo. The weight of the vehicle body alone of these large vehicles is not very large considering the output of the engine, so when a large vehicle equipped with a normal manual transmission has less than an appropriate amount of cargo, it is necessary to start driving in 2nd or 2nd gear. I often start in 3rd gear.

On the other hand, a system has been developed in which the clutch and transmission used in the above-mentioned manual transmission type large vehicles are controlled by an electronic control device configured with a microcomputer as if operated by a driver. When this type of automatic driving control device is applied to a large vehicle such as a truck or bus, the select lever is first switched to the "D" (drive) range.When the vehicle is started, the transmission is normally switched from 2nd gear for the reasons mentioned above. It is configured to start the vehicle.

In order to use the engine brake properly when dismounting, etc., when the select lever is placed in the 2nd, 3rd, or 4th gear position, the transmission will shift to the corresponding gear 2.
It is also configured to be fixed at either the 3rd, 3rd or 4th gear positions.

(Problem to be solved by the invention) In a large vehicle equipped with an automatic driving control device as described above, when starting on a flat road with a small load, it is difficult to start from 2nd gear without insufficient driving force. However, if the vehicle is overloaded or is starting on a boarding road, the gear will be set to 2.
In the first or third gear, the driving force is insufficient and the clutch is often in a half-engaged state, causing the problem of premature clutch wear.

The present invention has been made in order to improve the conventional drawbacks as described above, and its purpose is to, in a vehicle equipped with an automatic driving control device, when the driving force of the vehicle is insufficient, regardless of the position of the select lever. An object of the present invention is to provide an electronically controlled automatic transmission capable of shifting the transmission to an optimum gear.

(Means for solving the problem) According to the present invention, means for detecting the engine rotation speed;
An electronic device having means for detecting the rotational speed of an input shaft of a transmission, and means for comparing detection signals from both of these means and downshifting the transmission to a lower gear when the rotational speed difference exceeds a predetermined value. A controlled automatic transmission is provided.

(Function) In the present invention, the engine speed and the speed changer input shaft speed are compared, clutch slippage is detected, and when it is determined that there is insufficient driving force at the time of starting, the speed changer is set to the optimum gear. Force downshift.

Furthermore, when the above-mentioned forced gear down is performed, the gear stage display device blinks to notify the driver of this fact.

(Example) Next, an example of the present invention will be described in detail using the drawings.

FIG. 1 is a configuration block diagram showing one embodiment of an electronically controlled automatic transmission according to the present invention, and Chart 1 is a chart showing the relationship between selection control of a solenoid valve and gear position.

In FIG. 1, 1 is a shift actuator, which selectively controls opening and closing of electromagnetic valves v1 and v2 that supply oil pressure to oil chambers 1b and lc provided in a cylinder 1a.
, N, , R stage or 3. Piston rod ld is switched to three positions, such as N2.2 stage.

2 is a select actuator, which selectively controls the opening and closing of electromagnetic valves V5 + V4 * V 5 that supply hydraulic pressure to oil chambers 2 b , 2 c , and 2 d provided in the cylinder 2 a, thereby controlling N l , N 2 , N 5 * N 4 4
The piston rod 2e is switched to the position.

3 indicates a stroke sensor, and shift actuator l
The actuation position of the piston rod ld is detected, and the detected signal is sent to the electronic control device 5, which will be described later.

5l-34 is a select switch that detects the operating position of the piston rod 2e of the select actuator 2;
The detection signal is sent to the electronic control device 5.

Note that 4a is a hydraulic power source that supplies hydraulic pressure to each oil chamber;
b is a hydraulic oil tank.

As shown in Figure 1, by selectively controlling the solenoid valves vl to ■5, hydraulic pressure is applied to the respective oil chambers 1b, lc, 2b, 2c, and 2d.
The relationship between gear positions when piston rods 1d and 2e are actuated is shown.

Diagram 1 Next, in FIG. 1, the electronic control device 5 is composed of a microcomputer, and has a central processing unit, various memories, and input/output devices. In addition to receiving signals from the stroke sensor 3 and select switches 51 to S4, a clutch sensor 01 detects clutch operation.
, an accelerator sensor 02 that detects the operation position of the accelerator pedal 6, a vehicle speed sensor 03, an engine output shaft rotation sensor 0
4. Various detection signals are input from the transmission input shaft rotation sensor 05, the select sensor 07 that detects the select position of the select lever 7, etc., and based on these signals, the electromagnetic valves V1 to V5 and the clutch actuator (not shown) are activated. is configured to control the

8 is a gear stage display device, and select actuator 2
The gear position shifted by the shift actuator 1 is displayed to the driver, and if a downshift operation is performed due to insufficient driving force as described later, the shift actuator 1 is configured to blink as a warning means.

FIG. 2 is a processing flow diagram showing an example of the processing of this embodiment, and the operation of this embodiment will be explained with reference to FIG.

First, in step a, a gear change step is selected by operating the select lever 7 by the driver.

It is checked whether the vehicle is in 2nd or 3rd gear, and if it is in any of these gears, the process proceeds to step b, where it is determined whether a downshift has already been made. And stroke sensor 3
If the current gear is the first gear according to the signals from the select switch 5L-S4, the process proceeds to step i and the gear display 8 is made to blink.

If the gear is not shifted down in step b, the state of the clutch is checked in step d. Here, the signal from the clutch sensor Of provided in the clutch is checked, and if the clutch is engaged, the process proceeds to step e, where the difference in rotational speed between the engine output shaft and the transmission input shaft is checked.

If this rotational speed difference is less than the predetermined set value in step e, the clutch slippage is small, so proceed to step k.
If the rotation speed difference is greater than the set value.

In step f, it is checked whether the duration of the rotational speed difference is longer than a predetermined set time. This is because when the clutch slippage is small and the duration of one rotational speed difference is short, it means that the half-clutch state was short-lived, so this is removed from the downshift operation which is the gist of this embodiment. therefore,
If the rotation speed difference is greater than or equal to the set value in step e, and the duration is greater than or equal to the set time in step f, step g
Then, the current gear stage -1 is set as the optimum stage.

Then, predetermined commands are sent to the clutch actuator, shift actuator, and select actuator to activate hydraulic pressure, and a gear shift operation is performed to a gear position one gear lower than the current gear (step h).

Next, at step i, the gear stage display device 8 flashes to indicate that the gear has been downshifted, and at step j,
Start the vehicle by operating the clutch for normal starting.

Although the present invention has been described by way of one embodiment, various modifications can be made within the scope of the gist of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) According to the present invention, clutch slippage is detected based on the rotation speed difference between the output shaft of the engine and the input shaft of the transmission when the vehicle is started, and if the slippage is greater than or equal to a predetermined set value, selection is made. Since the gear is shifted to a lower gear than the gear currently set, smooth start-up is possible without running out of engine driving force, and the wear of the clutch is also reduced, resulting in a longer service life. 1. According to the present invention, the gear display device is made to blink when the gear is automatically shifted to a low speed, so that the driver can grasp the operation of the transmission.

[Brief explanation of the drawing]

FIG. 1 is a configuration block diagram showing one embodiment of an electronically controlled automatic transmission according to the present invention, and FIG. 2 is a processing flow diagram showing an example of the processing of this embodiment. l...Shift actuator, 2...Select actuator, 5...Electronic control device, 8...Gear stage display device, 04...Engine output shaft rotation sensor, 05...
...Transmission input shaft rotation sensor.

Claims (2)

[Claims] (1) A means for detecting the rotational speed of the engine, a means for detecting the rotational speed of the input shaft of the transmission, and the detection signals from both means are compared and the gear is changed when the difference in the rotational speed exceeds a predetermined value. 1. An electronically controlled automatic transmission comprising means for downshifting the transmission to a lower gear. (2) The electronically controlled automatic transmission according to claim (1), wherein a warning means is activated when the downshifting means is activated.