We have employed A5SR2, the 5th speed automatic transmission with full range electronic control and sports mode that provides smooth driving with lesser transmission shock as well as pleasant driving from manual transmission.
A/t electronic control system is the system where an optimized transmission has been realized from taking a grasp of driving status, A/T internal status at A/T control unit that has integrated with control valve assembly.
This paper describes apparatus cross-sectional view, major controls and control circuit diagram, major components and their functions, and etc.
Item | Contents |
Improved transmission feel | - Integrated control over engine and A/T (CAN communication control) system employed - Turbine sensor 1.2 employed - Real time feedback control at all phases applied |
Improved driving | - Sports mode function employed - Snow mode function employed (2WD applied) - Gear ratio extension |
Improved fuel consumption | - Slip lock-up employed - Full range lock-up employed (Larger lock-up zone) - E-flow torque converter employed (Improved driving efficiency) - Small transmission power train employed |
Improved safety | - Transmission lock apparatus (P range maintenance apparatus affixed) employed |
Improved maintenance | - Electronic system diagnosis tester (hi-scan) counterpart |
Part name | Acronyms | Function |
Front brake | F/B | Fastens the front sun gear |
Input clutch | I/ C | Engages the input shaft, with the middle annulus gear and the front annulus gear |
Direct clutch | D/C | Engages the rear planetary carrier with a rear sun gear |
High ＆ low reverse clutch | H＆L R/C | Engages the middle sun gear with the rear sun gear |
Reverse brake | R/B | Fastens the rear planetary carrier |
Forward brake | FWD/B | Fastens the middle sun gear |
Low cost brake | LC/B | Fastens the middle sun gear |
1st one-way clutch | 1st OWC | Allows the rear sun gear to turn freely forward relative to the mid sun gear but fastens it for reverse rotation |
Forward one-way clutch | FWD OWC | Allows the mid sun gear to turn freely in the forward direction but fastens it for reverse rotation |
3rd one-way clutch | 3rd OWC | Allows the front sun gear to turn freely in the forward direction but fastens it for reverse rotation |
N range
Since the forward and reverse brakes are released, driving force of input shaft is not transmitted to output shaft.
P range
Since the forward and reverse brakes are released, as those in the N range, driving force of input shaft is not transmitted to output shaft.
Parking pawl that is linked with select lever parking gear meshes with and fastens output shaft mechanically.
D, M2, M3, M4, M5 range 1st speed
Fastens the front brake.
The front brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The 1st one-way clutch regulates reverse rotation of the rear sun gear.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
* Power Flow
Input shaft⇒Front internal gear⇒Front carrier⇒Rear internal gear⇒Rear carrier⇒Middle internal gear⇒Middle carrier⇒Output shaft
D, M3, M4, M5 range ratio 2nd
Fasten the front brake.
The front brake and the forward one-way clutch regulate reverse rotation of the mid sun gear.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
The direct clutch is coupled and the rear carrier and the rear sun gear are connected.
* Power Flow
Input shaft⇒Front internal gear⇒Front carrier⇒Rear internal gear⇒Rear carrier⇒Rear carrier⇒Middle internal gear⇒Middle carrier⇒Output shaft
D, M3, M4, M5 range 3rd speed
Fastens the front brake.
The 3rd one-way clutch regulates reverse rotation of the front sun gear.
The high ＆ low reverse clutch is coupled and the middle and rear sun gears are connected.
* Power Flow
Input shaft⇒Front internal gear⇒Front carrier⇒Rear internal gear⇒Rear carrier⇒Rear carrier⇒Middle internal gear⇒Middle carrier⇒Output shaft
D, M4, M5 range 4th speed
The front brake is released and sun gear turns freely forward.
The input clutch is coupled and the front and middle internal gears are connected.
Driving force is conveyed to the front internal gear, the middle internal gear, and the rear carrier and the three planetary gears rotate forward as a unit.
* Power Flow
Input shaft⇒Front internal gear⇒Front carrier⇒Rear internal gear⇒Rear carrier⇒Middle internal carrier⇒Middle carrier⇒Output shaft
D, M5 range 5th speed
The front brake fastens the front sun gear.
The direct clutch is released and the rear carrier and rear sun gear are disconnected.
* Power Flow
Input shaft⇒Front internal⇒Front carrier⇒Rear internal input shaft⇒Middle internal⇒Rear carrier⇒Rear sun gear⇒Middle sun carrier⇒Middle carrier⇒Output shaft
R range
The front brake fastens the front sun gear.
The high ＆ low reverse clutch is coupled and the middle and rear sun gears are connected.
The reverse brake fastens the rear carrier.
* Power Flow
Input shaft⇒Front internal⇒Front carrier⇒Rear internal⇒Rear sun gear⇒Middle sun gear⇒Middle carrier⇒Output shaft
Input to ECM(CAN) | Output to ECM(CAN) | Input from external sys. | Output to external sys. |
- | - | A/T driving mode SW | Self-diagnosis indicator |
Engine torque signal | Output revolution signal | Sports mode SW | Range signal (P, R, N, D) |
Engine revolution signal | Turbine sensor signal | Up SW | Range signal |
- | Torque reduction request signal | Down SW | Reverse lamp signal |
Accelerator opening signal | Stop lamp SW | N position signal | |
Power | 4 x 4 Low signal |
Line Pressure Control
If the engine control unit sends the input torque signal equivalent to the engine driving force to the A/T control unit (TCM), the A/T control unit (TCM) controls line pressure solenoid.
This line pressure solenoid controls the pressure regulator valve as the signal pressure and adjusts the pressure of the operating oil discharged from the oil pump to the line pressure most appropriate to the driving plate.
Line pressure control based on line pressure characteristic pattern of A/T control unit (TCM)
A/T control unit (TCM) has stored in memory a number of patterns for the optimum line pressure characteristics according to driving conditions.
In order to obtain the most appropriate line pressure characteristic to meet the current driving state, the TCM controls the line pressure solenoid current valve and thus controls the line pressure.
- Normal line pressure control. Each clutch is adjusted to the necessary pressure to match the engine drive force.  - Back-up control (Engine brake) Line pressure according to speed is set during shift down by select operation while driving.  - During shift change Set to line pressure that is necessary for shift change. Therefore, line pressure characteristic is set according to input torque and shift types.  - At low fluid temperature When the A/T fluid temperature drops below the prescribed temperature, in order to speed up the action of each friction element, the line pressure is set higher than the normal line pressure characteristic.  |
Shift control
The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus the clutch pressure is adjusted to be appropriate to the engine load state and vehicle driving state. It becomes possible to finely control the clutch hydraulic pressure with high precision and a smoother shift change characteristic is attained.
Shift description
Controls clutches with optimum timing and fluid pressure in response to engine speed, engine torque information, and etc.
Lock-up Control
Lock-up control is to enhance delivery efficiency by preventing the torque converter from slipping, engaging the lock-up piston into the torque converter.
It operates lock-up solenoid control in response to a signal from A/T control unit (TCM) and lock-up control valve behavior control, engages or releases the lock up piston of the torque converter.
Lock-up control valve control
In the lock-up control valve, there is operating fluid pressure circuit linked into the lock-up piston and lock-up solenoid operates valve shift in response to a signal from the A/T control unit.
Operating fluid pressure circuit that is applied to the lock-up piston chamber is controlled with the release or apply sides.
Lock-up released
In the lock-up control valve, there is operating fluid pressure circuit connected into the lock-up piston and lock-up solenoid operates valve shift in response to a signal from the A/T control unit.
Therefore, the lock-up piston is not coupled.
Lock-up applied
During the lock-up applied status, lock-up apply pressure is generated having the lock-up control valve to L/U by the lock-up solenoid.
Therefore, press the lock-up piston to be coupled.
Smooth lock-up control
A/T control unit (TCM) controls current value that is output to the lock-up solenoid when shifting lock-up applied state from lock-up released state.
Therefore the lock-up clutch is temporarily set to half-clutched state when shifting the lock-up applied state to reduce the shock.
Half-clutched state
Changes current value that is output to the lock-up solenoid from A/T control unit (TCM) to gradually increase lock-up solenoid pressure.
In this way, the lock up apply pressure gradually rises and while the lock-up piston is put into half-clutched status, the lock-up piston operating pressure is increased and the coupling is completed smoothly.
Slip lock-up control
In the slip region, A/T control unit controls current value of the lock-up solenoid to half-clutched status. Therefore lock-up operates from low speed absorbing torque fluctuation of engine.
Thereby fuel consumption was increased during low accelerator opening with 4th, and 5th gears at low speed.
Engine Brake Control
The forward one-way clutch delivers driving force from the engine to the rear wheel but reverse driving from the wheel drive is not delivered since the one-way clutch is idling.
Therefore low coast brake solenoid is operated to prevent the forward one-way clutch from idling so that the engine brake is operated in the same as before.
The operation of the low coast brake solenoid switches the low coast brake switch valve and controls the coupling and releasing of the low coast brake.
The low coast brake reducing valve controls the low coast brake coupling force.
Valve name | Function |
Torque converter regulator valve | Regulates line pressure to the optimum pressure (torque converter operating pressure) to prevent pressure applied to the torque converter from being excessive. |
Pressure regulator valve Pressure regulator plug Pressure regulator sleeve | Regulates oil pump discharge pressure to the optimum pressure (line pressure) in response to the driving conditions. |
Front brake control valve | Regulates line pressure to the optimum pressure (front brake pressure) to be applied to the front brake during the front brake apply. |
Accumulator control valve | Regulates pressure applied to the accumulator piston, and the low coast reducing valve (accumulator control pressure) inresponse to the driving conditions (regulates clutch pressure at 1st, 2nd, 3rd, 5th gears). |
Pilot valve A | Regulates line pressure to the regular pressure required by line pressure control, shift control, and lock-up control (pilot pressure). |
Pilot valve B | Regulates line pressure to the regular pressure required by shift control (pilot pressure). |
Low coast brake switching valve | Provides the low coast brake reducing valve with line pressure during engine brake operation. |
Low coast brake reducing valve | Regulates line pressure to the optimum pressure to be applied to the low coast brake when the low coast brake is coupled. |
N-R accumulator | Produces the stabilizing pressure for when N-R is selected. |
Direct clutch piston switching valve | Operates in 4th gear and switches the direct clutch coupling capacity. |
High＆low reverse clutch control valve | Regulates line pressure to the optimum pressure (high＆low reverse clutch pressure) to be applied to the high＆low reverse clutch when the high＆low reverse clutch is coupled (regulates clutch pressure in 1st, 3rd, 4th, 5th gears). |
Input clutch control valve | Regulates line pressure to the optimum pressure (input clutch pressure) to be applied to the input clutch when the inputclutch is coupled (regulates clutch pressure in 4th, 5th gears). |
Direct clutch control valve | Regulates line pressure to the optimum pressure (direct clutch pressure) to be applied to the direct clutch when the direct clutch is coupled (regulates clutch pressure in 2nd, 3rd, 4th gears). |
Lock-up control valve Lock-up control plug Lock-up control sleeve | Switches lock-up to operating or released. Also, by performing the lock-up operation transiently, lock-up smoothly. |
Torque converter lubrication valve | Operates to switch torque converter, cooling, and oil path of lubrication system during lock-up. |
Cool bypass valve | Allows excess oil to by pass cooler circuit without being fed into it. |
Line pressure relief valve | Discharges excess oil from line pressure circuit. |
N-D accumulator | Produces the stabilizing pressure for when N-D is selected. |
Manual valve | Delivers line pressure to each circuit in response to each select position. Circuit to which line pressure is not sent drain. |
Name | Function |
Fluid pressure switch 1 (FR/B) | Detects abnormal fluid pressure of the front brake. When it detects any malfunction, it puts the system into fail-safe mode. |
Fluid pressure switch 2(LC/B) | Detects abnormal fluid pressure of the low coast brake. When it detects any malfunction, it puts the system into fail-safe mode. |
Fluid pressure switch 3(I/C) | Detects abnormal fluid pressure of the input clutch. When it detects any malfunction, it puts the system into fail-safe mode. |
Fluid pressure switch 5(D/C) | Detects abnormal fluid pressure of the direct clutch. When it detects any malfunction, it puts the system into fail-safe mode. |
Fluid pressure switch 6 (H＆LR/C) | Detects abnormal fluid pressure of the high＆low reverse clutch. When it detects any malfunction, it puts the system into fail-safe mode. |
Installing location: The valve body upper part
Function: To obtain A/T fluid pressure stability by compensating for solenoid＆valve body unit fluid pressure differential.
Principle: Install additional ROM onto valve body of automatic transmission and input fluid pressure differential of solenoid ＆valve body so that TCM reads the input data to perform fluid pressure compensation.
Maintenance
When replacing with a new TCM in the vehicle
TCM automatically reads SUB ROM DATA during I.G ON. At this time, shift range valve is off for about 2.5 second.
When replacing A/T (regardless of new or old ones) in the vehicle
Must erase SUB ROM DATA stored in TCM.
Erase SUB ROM DATA in SCAN TOOL delete mode during shift stage in R-range + accelerator opening angle maintains 50% + I.G ON.
TCM reads SUB ROM DATA from a new A/T upon I.G ON again after I.G OFF.
Moving TCM from vehicle A to another vehicle B
Perform the same way as in 2) above.
