Hộp số tự động 1 Bản quyền của tập đoàn ô tô Kia Người dịch: NNT - BPDV CNMB Mục lục Chủ đề Trang Các vị trí của cần số 3 Trang bị số tự động trên các đời xe và cách nhận biết 5 Bảo trì hộp số tự động 7 Các yêu cầu về dầu số tự động 9 Kiểm tra rò rỉ dầu số tự động 10 Công tắc số 11 Sơ lược hoạt động và phòng ngừa hưu hỏng 13 Các vị trí của cần số Để tránh cần số dịch chuyển không mong muốn đến một vị trí khác, gây mất an toàn cho người và xe, cần số chỉ dịch chuyển được sau khi có một động tác nhất định nào đó xác nhận cho chuyển số. Ví dụ như phải ấn nút khóa cần số hoặc chuyển nó sang rãnh ngang để chuyển về vị trí số thấp khi lái xe đổ đèo. Cần số có thể được lắp trên sàn hoặc trên cột tay lái. Như minh họa trên hình vẽ, một vài số tự động hiện đại có chế độ số thể thao. Đối với các xe có trang bị hộp số tự động loại này, người lái xe có thể lái khi cần số ở vị trí D. Khi chuyển sang cửa số thể thao (hay còn gọi là cửa số tay, người lái có thể chuyển số theo mong muốn như khi lái xe số sàn (số tay). Tuy nhiên, cũng cần lưu ý rằng, hộp điều khiển hộp số sẽ không cho phép chuyển số về những số không hợp lý như khởi hành xe ở số 3. Một vài loại xe đắt tiền trang bị cơ cấu khóa tay số. Khi đó, muốn chuyển tay số khỏi vị trí D thì cần đút khóa điện vào ổ khóa, xoay khỏi vị trí “LOCK” đồng thời đạp chân phanh. Chú ý rằng, để lấy chìa khóa khỏi ổ thì phải chuyển cần số về vị trí P. Khóa cần số được điều khiển bằng điện thay vì bằng cơ khí. Hoạt động của xe trang bị số tự động: Tùy thuộc vào từng đời xe mà có sơ đồ chuyển cần số khách nhau: 4 vị trí cộng thêm cửa số thể thao, 7 vị trí ,hoặc một vài đời xe có công tắc bật tắt số truyền tăng. Công dụng của các vị trí tay số: Vị trí P được dùng khi đỗ xe (người lái tắt máy, rút khóa điện ra khỏi ổ và ra khỏi xe). Trục đầu ra của hộp số được khóa bằng cơ cấu cơ khí. Khi đó xe không thể dịch chuyển được. Khi tay số ở vị trí P, người lái có thể đề nổ máy. Vị trí R được dùng khi cần lùi xe. Không thể đề nổ máy khi tay số ở vị trí này. Đèn lùi sẽ sáng. Vị trí N được sử dụng khi dừng xe tạm thời mà không phải đạp phanh. Trục đầu ra hộp số không bị khóa, có thể đề nổ máy. Vị trí D được dùng khi lái xe. Đây là vị trí số tiêu chuản khi lái xe trên đường thông thường. Việc chuyển số diến ra tự động với tất cả các số Shifting is made automatically through all forward gears. No starting possible. If the brake is not depressed the car will have a tendency to move forward (creeping). Position 3 allows automatic shifting from 1-3 gear .Some models have an overdrive switch instead of lever position 3. In this case switching off the overdrive does exactly the same function. No starting possible. Position 2 allows shifting between 1 and 2 gear only. No starting possible. Position L fixes the transmission into 1 gear. No starting possible. The reasons to allow only limited automatic shifting are basically: to avoid unintended forward and backward shifting during uphill driving and to have a better engine brake performance during downhill driving. In case of a sports mode transmission there is no 3, 2, L position as the gear can be selected by moving the lever into the manual gate and using + /- to fix a specific gear. Note: in previous purely mechanically controlled transmissions there was another cable to be adjusted properly to achieve proper shifting of the transmission: the kick down cable. Model range and identification In order to cope with the specific needs for different vehicles and markets KIA uses several different automatic transmissions in the product range, such as : Model: FRA is a 4-speed electronic controlled front wheel driven automatic transaxle produced by JATCO, Japan, for 1.1ε Engine, application: Picanto The A4AF3 model is the latest development among the alpha automatic transaxles (advanced alpha A/T). It is a 4-speed electronic controlled front wheel driven transaxle produced by KMC. Application: Rio (JB), Cerato (LD). The vehicles equipped an alpha engine) Model: F4A series and F5A series The F4A51 model is a HIVEC 4-speed electronic controlled front wheel driven automatic transaxle produced by KMC and installed on the vehicle that has the engine volume of 2.0L or more. The F5A51 model is a 5-speed electronic controlled front wheel driven automatic transaxle produced by KMC and is based on the 4 speed version. Depending on the actual vehicle there are several versions available, such as the A5H for the Grand Carnival (VQ). Also for the 4 speed transmissions several versions are available. Model F5A51 is a kind of 5-speed HIVEC electronic controlled front wheel driven automatic transaxle produced by KMC, and this is most big one among HIVEC 5-speed A/T. Application: OPIRUS (GH) The identification number is stamped as a row of with 6 sections as indicated below. 1st Digit: T/M model M: F4A42-1 N: F4A42-2 P: F5A51-2 2nd Digit: Product year W: 1998 X: 1999 Y: 2000 3rd Digit : Final gear ratio N: 4.042, K: 3.333, M: 3.770 4th Digit: Classification of detail 5th Digit: Spare 6th Digits: Serial Number 000001∼999999 Maintenance If the level is low, the oil pump will draw in air along with the fluid, which will cause bubbles to from inside the hydraulic circuit. This will in turn cause the hydraulic pressure to drop, which will result in late shifting and slipping of the clutches and brakes. If there is too much ATF, the gears can churn it up into foam and cause the same conditions that can occur with low fluid levels. In either case, air bubbles can cause overheating and oxidation of the fluid which can interfere with normal valve, clutch, and brake operation. Foaming can also result in fluid escaping from the transmission vent, in which case it may be mistaken for a leak. How to check the fluid level properly: 1. Run the engine until the fluid temperature rises to operation temperature (70-80°C) 2. Park the vehicle on a flat surface. 3. Move the selector lever through all positions to fill the torque converter and the hydraulic circuits with ATF. And put the select lever on “N” position. 4. Check the oil level and condition with level gauge after wiping off any dirt around the oil level gauge. If the fluid smells burned, it means that the fluid has been contaminated be fine particles from the bushes and friction materials; a transmission overhaul and flushing may be necessary. 5. Check the ATF level is on “HOT” mark on the gauge. If level is lower than this, replenish the ATF up to “HOT” mark. 6. Securely insert the oil level gauge. 7. The fluid and the oil filter should always be replaced when overhauling the transmission or after the vehicles have been driven under severe conditions. In addition to the main oil filter inside of A/T, a sub oil filter has been adopted on some transmissions (Hivec), to filter the fine impurities not filtered at the main oil filter at all times. Pay attention: these oil filters are special filters that are only to be used for the automatic transmission. The sub oil filter and the engine oil filter look similar. They can be distinguished by the identification mark, “A/T only” at the upper side of the AT sub oil filter. Before installing the new sub oil filter, apply a small amount of automatic transmission fluid to the O-ring. When tightening the drain plug make sure to use a new gasket and the correct tightening torque. If you have to ad ATF fluid or if you have to replace it make sure that you use the correct fluid, as the use of wrong fluid may lead to shift problems or damage the transmission ATF fluid requirements As the automatic transmission fluid pays an important role for the proper function of the transmission it is important to keep it in good condition. Therefore it is mandatory to follow the periodic maintenance schedule precisely. The maintenance includes not only fluid level check, but also the replacement of the fluid in specific intervals depends on model and market. When replacing the fluid follow the given procedures from the workshop manual precisely and take special care to use the correct fluid, as different types are available. Using the wrong fluid can cause not only poor shift quality, but lead to a complete transmission break down. New, ATF (Automatic Transaxle Fluid) should be red, because red dye is added to distinguish it from engine oil or antifreeze. As the vehicle is driven, the transaxle fluid will begin to look darker. The color may eventually appear light brown. Also, the dye, which is not an indicator of fluid quality, is not permanent. Therefore, do not use fluid color as a criterion for replacing the transaxle fluid. However, further investigation of the automatic transaxle is required if the fluid is dark brown or black, if it smells burnt or particles can be seen or felt on the dipstick. Again: Be aware to use the correct fluid!! As the wrong one may cause problems such as shift shocks, judder or even damage to the transmission proper. Inspection for leakage If transmission fluid has to be added, do not only replenish, but check for leakage as well. In the given sample you can see the major possibilities for leakage to occur. Please note that overfilling may cause oil to be pushed out from the breather or the dip stick. Therefore make sure to detect the correct cause for oil coming out from the transmission. Inhibitor switch In a mechanical controlled transmission the inhibitor switch is a pure start safety mechanism. When the selector lever is not in position “P” or “N”, the electrical circuit for starting the engine is in the OFF state. Therefore, the engine does not start in this condition, even if the ignition switch is turned to the “START” position. The inhibitor switch is installed on the transaxle case and connected with the manual control shaft. The inhibitor switch includes also internal circuits for the detection of the selector lever position this signals are used for the indication of the selected gear in the instrument cluster. In case of electronic controlled transmissions, as for example the Hivec series, the signals of the shift position are used by the electronic control unit for the selection of the proper shift range. The correct electrical function of the switch can be checked by multimeter, measuring the continuity between the related terminals. The picture above shows a sample only, as different versions are existing. To see the individual layout, please refer to the Workshop manual. In case of any discrepancy, check if the switch is installed and adjusted in the correct position. If the adjustment is o.k., replace the switch. In that case make sure to use the correct one, as different versions are available. Inhibitor switch and control cable adjustment: 1. Set the selector lever to the “N” position. 2. Loosen the control lever coupling nut so that the control cable and lever are free. 3. Set the manual control lever to the neutral position. 4. Loosen the inhibitor switch mounting bolts and turn the inhibitor switch body so that the hole in the end of the manual control lever and the hole (cross section A-A in the figure) in the flange of the transaxle range switch body flange are aligned. 5. Tighten the transaxle range switch body mounting bolts to the specified torque. Be careful at this time that the position of the switch body is not changed. 6. Gently pull the transmission control cable in the direction of front side of vehicle in order to eliminate to much free play, and then tighten the adjusting nut. 7. Re-check that the selector lever is in the “N” position. 8. Check that each range on the transmission side operates and functions correctly for each position of the selector lever. General operation and precautions This picture shows the basic outline of an modern automatic transmission In former times an automatic transmission was controlled by the hydraulic system only and had two main sections: hydraulic and the mechanical. Nowadays an automatic transmission consists of 3 main sections: Mechanical section, hydraulic section and electric or electronic section. The function of each part of the transmission is as follows: Torque converter: transmits the engine torque to the transmission by automatic transmission fluid Oil pump: pressurizes the automatic transmission fluid Hydraulic control system: regulates the pressure and directs the fluid to the clutches and brakes Electronic control system: collects the data by the means of sensors. Based on this input the control unit drives the actuators (solenoids) in order to control the gear shifting. The torque converter transmits the torque to the transmission and drives the oil pump. The pump creates pressure, which is applied to the hydraulic control system. The sensors detect the operating conditions and send this information to the control unit. Using this input and the internal map the control unit determines necessary gearshifts and activates the solenoids accordingly. The hydraulic pressure is then routed to the clutches and brakes in accordance with the activated solenoids. Depending on the activated clutch or brake different parts of the gear train are connected or held stationary in order to achieve the necessary gear shift. Note: in early transmissions the control was made without electronic control. Gear shifting was made only by the hydraulic control system using mechanical valves reacting on pressure changes related to speed (governor) and throttle position (throttle cable). Creeping phenomenon The engine power is transmitted from the engine to the transmission via the automatic transmission fluid (inside of the torque converter). Even in the transmitted torque is strong enough to move the vehicle if no brake is applied. Therefore it is necessary to select N, if the driver does not want to depress the brake during the stop. Towing automatic transmission vehicles. In the case you have to tow a car with automatic transmission, the towing distance and the towing speed must be limited. As a rule of thumb: maximum towing distance is 50 km and maximum towing speed is 50km/h. For exact figures, please refer to the owners manual of the specific vehicle. As the oil pump is not operated during towing, these limits are important to prevent seizure of the internal parts of the transmission. If you have to tow the vehicle for a longer distance or faster than 50 km/h or if the vehicle has an internal transmission fault special measures must be taken. For example lifting the vehicles driven wheels or best : using a flat bed truck.