Characteristics and fault analysis of the hottest

2022-08-15
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Characteristics and fault analysis of AL4 automatic transmission

AL4 electronic automatic transmission is a fully electronic controlled, fully enclosed and less maintenance automatic transmission jointly developed and designed by French PSA group and different Renault companies with different force values measured at different loading rates. This automatic transmission is mainly used in Fukang, Elysee, Picasso, Citroen C5 and other imported Citroen, Peugeot and Renault cars

I. characteristics of AL4 automatic transmission

1. Structural characteristics of AL4 automatic transmission

al4 electronic automatic transmission adopts fuzzy logic automatic adaptation electronic control unit, which can automatically identify the driver's type, road conditions and vehicle load, and adapt the best shift law. Due to its intelligent function, it can accurately control gear shifting and main oil circuit pressure, and control the movement of hydraulic torque converter piston through the flow of radiator. If the sensor and solenoid valve are abnormal, there will be warning signals on the gear display

the interconnection of automatic transmission electronic control unit and engine electronic control unit enables them to transmit signals to each other, and makes the locking of hydraulic torque converter and the engagement of clutch and brake smoother, thus greatly improving the driving comfort and handling stability. In addition, the electronic control unit controls various solenoid valves to prevent the driver from misoperation, which improves the safety of the vehicle

2.al4 electronically controlled automatic transmission mode switch

al4 automatic transmission has three transmission modes of "normal", "Sports" and "Snow". After the experiment of automatic transmission joystick, you can recall the three mode selection keys on the mode selection control panel on the right side of the experimental curve to select the mode. The selection and operation of each mode are as follows

(1) normal mode. This mode is the default selection, and the automatic transmission automatically operates in this mode without pressing any key. When the electronic control unit controls the automatic shift of the automatic transmission, fuel saving is the priority. This mode is applicable to all kinds of ordinary roads

(2) movement mode. Press the "s" key, and the "SPT" indicator light on the instrument panel is on. At this time, the automatic transmission enters the sports mode automatic shift program. In this mode, when the electronic control unit controls the automatic shift of the automatic transmission, the power performance is the priority, that is, the driving performance and acceleration performance are guaranteed first

(3) snow mode. Press the "*" key, and the "*" indicator light on the instrument panel is on. At this time, the automatic transmission enters the snow mode and the automatic shift program. This mode is suitable for driving on low adhesion roads. The electronic control unit controls the automatic transmission to start with second gear to prevent the driving wheel from slipping

(4) force the first gear mode. When the automatic transmission control handle is in position 2, press the "1" key on the mode selection control panel, and the automatic transmission will always work in gear 1

II. Transmission system structure of AL4 automatic transmission

al4 automatic transmission adopts series Simpson II planetary gear mechanism. Its front planetary carrier is connected with the rear ring gear, and the front ring gear is connected with the rear planetary carrier. The force application device is composed of two disc clutches, one belt brake and two disc brakes. The traditional Simpson planetary gear mechanism can only provide three forward gears and one reverse gear. To improve it to four speeds, one planetary row, one clutch, one one-way clutch and one brake need to be added. The Simpson 11 planetary gear mechanism can achieve four forward gears with only a composite planetary row, saving three force applying elements of the overspeed mechanism. Due to the public use of the composite planetary gear row, huozhenping, the head of graphene cable business of Jiangsu Zhongchao Cable Co., Ltd. (hereinafter referred to as "Zhongchao cable"), clarified: "First of all, the male wheel does not have a drum, which makes the volume of the automatic transmission smaller, just in line with the small displacement characteristics of French cars. There is no one-way clutch in the AL4 automatic transmission, and there are friction plates in the front and rear of the clutch disc in the hydraulic torque converter.

III. The electronic control system features of AL4 automatic transmission

1. Automatic control process

al4 automatic transmission control unit, through various sensors, will convert the engine speed and throttle Opening, vehicle speed, engine temperature, automatic transmission oil temperature and other parameters are converted into signals and input into the automatic transmission electronic control unit, which determines the automatic transmission shift control signal according to these signals. The shift signal output by the electronic control unit controls the action of the corresponding solenoid valve, and generates the corresponding hydraulic control signal through the two position reversing valve to make the relevant shift actuator act and realize automatic shift

2. automatic transmission control rules

in order to adapt the automatic shift control to the changes of vehicle load, driving conditions, roads and driving styles, AL4 automatic transmission electronic control unit has set up 10 control rules: ll is the economic rule, and it will enter the rule when the automatic transmission oil temperature reaches 30 ℃; L2 is an intermediate rule, between L1 and L3; L3 is the movement rule. The electronic control unit measures the driver's driving style or after the driver presses the "s" key, the automatic control gear shift will be superior to this rule; L4 is the rule of ascending gentle slope, and the power required for ascending gentle slope will be given priority during automatic control gear shifting; L5 is the rule of ascending steep slope, and the power required for ascending steep slope will be given priority during automatic shift control; L6 is the downhill rule, which makes the gear shift lag when it is flat, so as to facilitate the engine braking; L7 is the snow rule, which is used on roads with low adhesion factor. The electronic control unit controls the automatic transmission to start in second gear to prevent wheel slip. Press the "*" key to enter this rule; L8 is a low temperature protection rule. When the automatic transmission oil temperature is lower than 14 ℃, enter this rule, and it is forbidden to lock the hydraulic torque converter; L9 is a high temperature protection rule. Enter this rule when the automatic transmission oil temperature is higher than 118 ℃, and the hydraulic torque converter is locked; L10 is an anti pollution rule, which is entered when the automatic transmission oil temperature is 15 ℃ ~ 30 ℃. Increase the idle speed of the engine to prevent pollution

3. AL4 automatic transmission control program

(1) normal control program. The automatic transmission oil temperature is 30 ℃ ~ 118 ℃, and the electronic control unit automatically enters this program to control the gear shift without pressing any key. Under this program, the electronic control unit selects the shift rules in ll ~ L6 according to the driver's driving style, load, road surface and other conditions for shift control

(2) motion control program. After pressing the "s" key, the electronic control unit will enter the program for shift control. Under this program, the electronic control unit preferentially selects the L3 rule, and then press the "s" key to cancel the L3 rule

(3) snow control procedure. After pressing the "*" key, the electronic control unit will enter the program for shift control. Under this program, the electronic control unit first selects the L7 rule

4. Control function of AL4 automatic transmission

(1) downshift control. The electronic control unit automatically controls the downshift according to the vehicle speed, throttle position and brake pedal, so as to make full use of the braking effect of the engine. The vehicle speed is stable. When the accelerator pedal is fully released, skip and downshift (4 → 2; 3 → 1); When loosening the accelerator pedal quickly, fix it in the original gear or downshift it by 1 gear; Downshift in advance when pressing the brake pedal

(2) instant acceleration. When the accelerator pedal is quickly pressed to the bottom under the control state of ll or L2 rule, the electronic control unit can instantly transition to the LL or L3 rule. When the accelerator pedal is released, it will return to the original rule control state

(3) rapid acceleration function. When the accelerator pedal is pressed sharply in a stable driving state, the electronic control unit automatically controls the downshift to obtain the power required for the rapid acceleration of the vehicle

(4) pressure control. In the closed-loop state (the electronic control system has no fault, and the automatic transmission oil temperature reaches a certain range), the electronic control unit controls the pressure of the main oil circuit according to the speed and the torque of the turbine

(5) shift solenoid valve connection control. During gear shifting, the electronic control unit controls the on and off of the shift solenoid valve to make the automatic transmission in the neutral state. After the oil cylinder of the original gear begins to drain, the new shift cylinder begins to fill oil. The time interval between draining and filling the two cylinders is determined by the electronic control unit according to the vehicle speed and the position of the throttle valve

(6) locking and separation of hydraulic torque converter. The electronic control unit determines whether the hydraulic torque converter is locked according to the vehicle speed, the position of the throttle valve, the speed of the engine, the shift rules of the input speed of the automatic transmission, etc., so as to avoid excessive oil temperature of the automatic transmission, reduce fuel consumption, and obtain engine braking through the locking of the hydraulic torque converter

(7) shift reduction torque control. During gear shifting, the automatic transmission electronic control unit outputs information to the engine electronic control unit to reduce the output torque of the engine by reducing the control of ignition advance angle, so as to reduce the impact during gear shifting

(8) idle speed compensation control. When the automatic transmission oil temperature is between 15 ℃ and 30 ℃, information is provided to the engine electronic control unit to improve the idle speed of the engine

(9) automatic transmission protection control. AL4 automatic transmission mainly has the following protection and control functions

reverse gear protection. When the vehicle speed is greater than 15km/h and the vehicle is shifted from position d to position R, the electronic control unit controls the automatic transmission not to enter reverse gear and the vehicle slides in neutral. At the same time, "n" flashes, and the brake light is on

error operation protection. When the vehicle speed is greater than the shift limit speed, when changing gears from D → 3, 3 → 2, the electronic control unit controls the automatic transmission to stay in place first, and then shift after a certain time delay

operation action is prohibited. When the speed of the engine is higher than a set speed, the electronic control unit will prohibit the shift operation of n → D or n → R, which needs to undergo deceleration and delay transition

(10) shift lever locking function. When the automatic transmission control lever is in the "P" position, the shift lever can be moved from "P" to other gears only when the ignition switch is turned on to the "m" position and the brake pedal is pressed at the same time

(11) display function on the instrument panel. The display functions of the automatic transmission control system on the instrument panel include: displaying the gear of the automatic transmission and the selected program through the liquid crystal display on the instrument panel; Through the alternating flashing of "SPT" and "*", it indicates that there is a fault in the automatic transmission

(12) prompt function for changing automatic transmission oil. The automatic transmission electronic control unit calculates the automatic transmission oil reading according to the automatic transmission oil temperature, working time under high temperature and other parameters. When the reading exceeds 32958, it indicates that the automatic transmission oil needs to be replaced by flashing "SPT" and "*" alternately

(13) self diagnosis function. The electronic control unit controls the power supply of the sensor and actuator and monitors whether they work normally. When there is a fault, the electronic control unit has the following functions: after confirming the fault, it warns by flashing the indicator light and stores the fault information; Information can be exchanged with diagnostic equipment through K-line; Make the automatic transmission electronic control system operate in the backup mode

(14) data update and password addition. The automatic transmission electronic control unit can update its data through the diagnostic equipment, and can also set the peripheral environment of the automatic transmission electronic control unit according to the options not installed on the vehicle

IV. common fault analysis

since AL4 automatic transmission has no dipstick, the method of checking the oil level is different. The correct inspection method is: under the idling condition of the engine, make the automatic transmission stay in each gear for a while (the time shall not be less than 5S). When

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