AUTOMATIC TRANSMISSION SYSTEM DETAILS

Line Pressure Control

1. The line pressure is controlled by using shift solenoid valve SLT (line pressure control solenoid assembly). Through the use of shift solenoid valve SLT (line pressure control solenoid assembly), the line pressure is optimally controlled in accordance with the engine torque information, as well as with the internal operating conditions of the torque converter and the transmission. Accordingly, the line pressure can be accurately controlled in accordance with the engine output, traveling condition and the ATF temperature, achieving smooth shift characteristics and optimizing the workload of the oil pump.

   

Clutch Pressure Optimal Control

1. The TCM monitors the signals from various types of sensors, such as the transmission revolution sensor (NT) and transmission revolution sensor (NC3), allowing shift solenoid valve SL1, SL2, SL3, SL4, SL5, SLT (line pressure control solenoid assembly) and shift solenoid valve SLU (lock up control solenoid assembly) to minutely control the clutch pressure in accordance with engine output and driving conditions. As a result, smooth shift characteristics are achieved.

   

Clutch to Clutch Pressure Control

1. Clutch to clutch pressure control is used for shift control. As a result, shift control in 2nd gear or above is possible without using the 1-way clutch, and the automatic transmission has been made lightweight and compact.

2. Using the fluid pressure circuit, which enables the clutches and brakes (C1, C2, C3, C4 and B1) to be controlled independently, and the high flow SL1, SL2, SL3, SL4 and SL5 shift solenoid valves, which directly control the line pressure, the TCM controls each clutch and brake accordingly with the optimum fluid pressures and timings in accordance with the information transmitted by the sensors, and then shifts the gears. As a result, highly responsive and excellent shift characteristics have been achieved.

   

Multi-mode Automatic Transmission

1. The driver can select the desired gear range by moving the shift lever to "+" (forward) or to "- " (backward) while the shift lever is in M. Also, the shift paddle switch (transmission shift switch assembly) can be used to change the gear range while the driver is holding the steering wheel. Thus, the driver is able to shift gears with a manual-like feel.

2. When the shift lever is in D, the driver can momentarily select a desired shift range by operating the shift paddle switch (transmission shift switch assembly). Automatic shifting will be reinstated under the following conditions:

   
   

   • The vehicle has stopped.

   • The driver continues to push the shift paddle switch (transmission shift switch assembly) in the "+" direction longer than 1 second.

   • The driver depresses the accelerator pedal for more than a predetermined amount of time.

3. When the vehicle is being driven at a prescribed speed or higher, any attempt to shift to a lower range by operating the shift lever will not be executed, in order to protect the automatic transmission. In this case, the ECM sounds the multi buzzer in the combination meter assembly twice to alert the driver.

   

4. When the shift lever is in M, the gear hold control, complete lock-up control, high response upshift control and blipping downshift control are used in order to improve response in accordance with the driver's operation of the accelerator pedal, shift lever or transmission shift switch, and to improve gear shift feeling.

   

5. Gear Hold Control

   
   

   • Gear shifting will not be performed under gear hold control as long as the shift lever or shift paddle switch (transmission shift switch assembly) is not operated. This makes it possible to make efficient use of the highest engine speeds. However, in the following cases, operation of gear hold control is limited.

     Automatic Shifting When Shift Lever is in M

     When the ATF or engine coolant temperature is low, gear shifting will be performed automatically. When the ATF temperature is high, gear shifting will be performed automatically.

6. Complete Lock-up Control

   
   

   • While the shift lever is in M, lock-up control operates from 2nd gear, transmitting the changes in engine power directly to the output shaft, the same way as with a manual transmission. As a result, direct response to the accelerator operation is achieved.

7. High Response Upshift Control

   
   

   • The high response upshift control achieves a highly responsive upshift operation using the clutch to clutch pressure control, which regulates each clutch and brake quickly and precisely, and using the powertrain cooperative control, which optimally regulates engine torque during shifting.

     

8. Blipping Downshift Control

   
   

   • The blipping downshift control regulates each clutch and brake using the clutch to clutch pressure control, allowing them to be engaged smoothly and disengaged quickly. In addition, fuel injection volume is increased and engine speed is boosted by the powertrain cooperative control, ensuring engine brake force. In this way, a smooth and quick downshift is achieved.

     

Linear Feel Improving Control

1. Conventionally, drive force was dependent on the accelerator pedal operation (throttle opening) and the gear position.

2. With the linear feel improving control, optimum engine torque (throttle opening) for the gear position is achieved, reducing the frequency of downshifting.

3. Continuous drive force has been achieved by reducing the variations in drive force when downshifting, improving controllability of the vehicle during accelerator pedal operation.

   

4. By reducing changes in the acceleration rate while the vehicle speed increases, a steady linear increase in vehicle speed that does not depend on the shift range has been achieved.

   

Coast Downshift Control

1. The TCM performs downshift control to prevent the engine speed from decreasing, thus keeping fuel cut control operating for as long as possible. In this way, the fuel economy is improved.

2. In this control, the transmission downshifts from 8th to 7th, 7th to 6th and then 6th to 5th before fuel cut control ends when the vehicle is decelerated in the 8th gear, so that fuel cut control continues operating. In addition, the TCM performs downshifting when the vehicle is decelerated both in the 6th and 7th gears.

   

Artificial Intelligence Shift Control (AI-shift Control)

1. The AI-shift control determines optimal transmission control based on input signals and automatically changes the shift pattern. As a result, excellent transmission operation is achieved.

2. The AI-shift control includes a road condition support control and a driver's intention support.

3. The AI-shift control is performed only with the shift lever in D, based on the accelerator pedal and brake operation data. The AI-shift control will be canceled when the shift lever is moved to any position other than D.

   

4. Road Condition Support Control

   
   

   • The TCM identifies the throttle valve opening angle, accelerator pedal opening angle and vehicle speed to determine whether the vehicle is being driven uphill or downhill. Unnecessary upshift is restrained to automatically achieve optimal drive force at all times while driving uphill. Downshift is automatically conducted to achieve optimal engine brake force, while driving downhill.

     

5. Driver's Intention Support Control

   
   

   • The driver's intention is estimated based on the accelerator pedal operation and vehicle condition, and a shift pattern that is well-suited to the driver's intention is selected without operating the combination switch assembly.

   
   

   1. Sudden Accelerator Pedal Release Control

   
   

   1. When the accelerator pedal is released suddenly, the transmission is kept in gear as long as possible, which improves engine braking force.

      

   2. Sudden Accelerator Pedal Depress Control

   
   

   1. When the accelerator pedal is depressed suddenly, downshifting occurs earlier, providing improved acceleration response.

      

   3. Downshift Control during Hard Braking

   
   

   1. High engine braking power and good reacceleration response have been achieved by actively downshifting during deceleration when hard braking is performed.

      

   4. G AI-shift Control

   
   

   1. When the vehicle enters a corner, this system assesses the overall vehicle condition based on signals from the G-sensor and the driver's intention, and downshifts to the appropriate gear to obtain the necessary driving force for coming out of a corner.

   2. Controllability during cornering is ensured by suppressing gear shifting.

      

Gear Shift Indicator System

1. The Gear Shift Indicator system is a system to promote upshifting to the fuel-efficient and optimal gear ranges in accordance with the driving conditions such as the accelerator pedal opening and the vehicle speed, etc. when the vehicle is running while the shift lever is in M.

2. By driving in accordance with the upshifting recommendations indicated by the multi-information display in the combination meter assembly and headup display, the driver can enhance environmental performance, improve fuel economy and reduce exhaust gas emissions within the limits of engine performance.

   

   Text in Illustration

   *a	Gear Shift Indicator	*b	Headup Display
   *c	Multi-information Display	-	-

Shift Lock System

1. The shift lock system prevents the shift lever from being moved to any position other than P, unless the engine switch is turned on (IG) and the brake pedal is depressed. This prevents the vehicle from starting off suddenly.

2. The shift lock system is controlled by the shift lock control ECU sub-assembly, and the system has a shift lock function.

3. The shift lock control ECU sub-assembly has a built-in P detection switch to detect the shift lever position, and receives input signals from the stop light switch assembly and engine switch. Upon receiving these signals, the shift lock control ECU sub-assembly turns on the shift lock solenoid in order to release the shift lock.

4. A shift lock release button, which manually overrides the shift lock mechanism, is used.

   

   Text in Illustration

   *1	Shift Lock Release Button	*2	Transmission Floor Shift Assembly
   *3	Shift Lock Solenoid Assembly Shift Lock Control ECU P Detection Switch	-	-

   

Torque Converter

1. A compact, lightweight and high-capacity torque converter assembly is used. The torque converter supports lock-up clutch control, improving fuel economy.

   

   Text in Illustration

   *1	Lock-up Damper	*2	1-way Clutch
   *3	Turbine Runner	*4	Lock-up Clutch
   *5	Stator	*6	Pump Impeller

Oil Pump

1. The oil pump is operated by the torque converter. The oil pump lubricates the planetary gear units and supplies operating fluid pressure for hydraulic control. The front oil pump drive gear is continually driven by the engine via the pump impeller. The pump has sufficient capacity to supply the necessary fluid pressure throughout all speed ranges, as well as in reverse.

2. The pump cover is made of aluminum to reduce weight.

3. A pump cover with an integrated piston cylinder for the No. 1 brake (B1) is used.

   

   Text in Illustration

   *1	Pump Body	*2	Drive Gear
   *3	Driven Gear	*4	Stator Shaft
   *5	Pump Cover	*6	No.1 Brake (B1)
   *a	No.1 Brake (B1) Piston Cylinder	-	-

Planetary Gear Unit

1. An 8-speed configuration has been achieved by using 2 planetary gear units, creating an 8- speed automatic transmission.

2. A Ravigneaux type gear unit is used as the rear planetary gear unit. The gear unit consists of pairs of sun gears (middle and rear) and planetary pinion gears (long and short) with different diameters within a single planetary gear.

3. The centrifugal fluid pressure canceling mechanism is used in the C1, C2, C3 and C4 clutches that are applied when shifting from 2nd to 3rd, from 3rd to 4th, from 4th to 5th, from 5th to 6th, from 6th to 7th and from 7th to 8th.

   

   Text in Illustration

   *1	No. 1 Brake (B1)	*2	No. 4 Clutch (C4)
   *3	Front Planetary Ring Gear	*4	Rear Planetary Gear Unit
   *5	No. 2 Clutch (C2)	*6	No. 2 Brake (B2)
   *7	No. 1 1-way Clutch	*8	No. 1 Clutch (C1)
   *9	No. 3 Clutch (C3)	-	-

   

   Text in Illustration

   *1	Input Shaft	*2	Front Planetary Sun Gear
   *3	Front Planetary Ring Gear	*4	Front Planetary Gear Unit
   *5	Intermediate Shaft	*6	Rear Planetary Middle Sun Gear
   *7	Rear Planetary Ring Gear	*8	Rear Planetary Gear Unit
   *9	Rear Planetary Rear Sun Gear	*10	Output Shaft
   *11	Rear Planetary Short Pinion Gear	*12	Rear Planetary Long Pinion Gear
   *13	Front Planetary Pinion Gear	-	-
   C1	No. 1 Clutch	C2	No. 2 Clutch
   C3	No. 3 Clutch	C4	No. 4 Clutch
   B1	No. 1 Brake	B2	No. 2 Brake
   F1	No. 1 1-way Clutch	-	-

Centrifugal Fluid Pressure Canceling Mechanism

1. The clutch engagement force during shift transmission is affected by the centrifugal fluid pressure that acts on the fluid inside the piston fluid pressure chamber (referred to as "chamber A"), in addition to the original clutch pressure regulated by the valve body. In order to eliminate the influence caused by the centrifugal fluid pressure, the canceling fluid pressure chamber (referred to as "chamber B") is provided on the opposite side of chamber A to cancel out the centrifugal fluid pressure. As a result, the centrifugal fluid pressure canceling mechanism provides responsive and smooth shift transmission.

   

   Text in Illustration

   *1	Piston	*2	No. 4 Clutch (C4)
   *3	No. 3 Clutch (C3)	*4	No. 1 Brake
   *a	Chamber A	*b	Chamber B

2. Chamber B is filled by fluid supplied to the shaft for lubrication. As a result of filling chamber B, the same amount of fluid pressure is present on both sides of the piston due to centrifugal force. This cancels the effects of fluid pressure on the piston caused by centrifugal force. Accordingly, it is not necessary to discharge the fluid through the use of a check ball, and highly responsive and smooth shifting characteristics are achieved.

   

Transmission Valve Body Assembly

1. The transmission valve body assembly consists of upper and lower valve bodies and 9 shift solenoid valves.

   

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   *1	Shift Solenoid Valve SR (Shift Solenoid Valve DSL)	*2	Shift Solenoid Valve SLT (Line Pressure Control Solenoid Assembly)
   *3	Shift Solenoid Valve SLU (Lock Up Control Solenoid Assembly)	*4	Shift Solenoid Valve SL1
   *5	Shift Solenoid Valve SL5	*6	Shift Solenoid Valve SL4
   *7	Shift Solenoid Valve SL3	*8	Shift Solenoid Valve SL (Transmission 3-way Lock Up Solenoid Assembly)
   *9	Shift Solenoid Valve SL2	*10	Lower Valve Body
   *11	Plate	*12	Upper Valve Body

   

   Text in Illustration (Upper Valve Body)

   *1	Lock-up Relay Valve	*2	Solenoid Regulator Valve
   *3	No. 1 Clutch Apply Control Valve	*4	No. 1 B1 Apply Control Valve
   *5	No. 2 Clutch Apply Control Valve	*6	C4 Relay Valve
   *7	Signal Check Valve	*8	No. 2 Clutch Apply Relay Valve
   *9	C2 Damper	*10	B2 Control Valve
   *11	B2 Check Valve	*12	No. 1 Clutch Apply Relay Valve
   *13	Solenoid Modulator Valve	*14	C1 Accumulator Valve
   *15	Lock-up Control Valve	-	-

   

   Text in Illustration (Lower Valve Body)

   *1

   Primary Regulator Valve

   *2

   B2 Apply Control Valve

Shift Solenoid Valve SL1, SL2, SL3, SL4, SL5, SLU and SLT

1. In order to provide a fluid pressure that is proportional to the current that flows to the solenoid coil, shift solenoid valve SL1, SL2, SL3, SL4, SL5, SLU and SLT linearly control the line pressure and clutch and brake engagement pressure based on the signals from the TCM.

2. Shift solenoid valve SL1, SL2, SL3, SL4 and SL5 are large flow linear solenoid valves that can supply more pressure than conventional ones. These shift solenoid valves control engagement elements by directly regulating the line pressure without using the pressure regulation valve or the pressure reduction valve. Thus, the number of valves and the length of the valve body fluid passage have been reduced, the shifting response has been improved and the shift shock has been minimized.

3. Shift Solenoid Valve SL1, SL3, SL4 and SL5

   

4. Shift Solenoid Valve SL2

   

5. Shift Solenoid Valve SLU (Lock Up Control Solenoid Assembly)

   

6. Shift Solenoid Valve SLT (Line Pressure Control Solenoid Assembly)

   

Shift Solenoid Valve SL and SR

1. A 3-way solenoid valve is used for shift solenoid valve SL and SR.

2. A filter is provided at the tip of the shift solenoid valves to further improve operational reliability.

3. Shift Solenoid Valve SL (Transmission 3-way Lock Up Solenoid Assembly)

   

4. Shift Solenoid Valve SR (Shift Solenoid Valve DSL)

   

Transmission Revolution Sensor

1. This automatic transmission uses the transmission revolution sensor (NT), transmission revolution sensor (NC3) and transmission revolution sensor (SP2). Thus, the TCM can detect the timing of the shifting of the gears and appropriately control the engine torque and fluid pressure in response to various conditions. These transmission revolution sensors are the Hall type.

2. The transmission revolution sensor (NT) detects the input speed of the transmission. The input shaft is used as the timing rotor for this sensor.

3. The transmission revolution sensor (NC3) detects the speed of the intermediate shaft. The No. 3 clutch (C3) drum is used as the timing rotor for this sensor.

4. The transmission revolution sensor (SP2) detects the speed of the output shaft. The rear planetary ring gear is used as the timing rotor for this sensor.

5. The Hall type transmission revolution sensor consists of a magnet and Hall IC. The Hall IC converts the changes in the magnetic flux density that occur through the rotation of the timing rotor into an electric signal, and outputs the signal to the TCM.

   

   Text in Illustration

   *1	Input Shaft	*2	Transmission Revolution Sensor (NT)
   *3	Transmission Revolution Sensor (NC3)	*4	Transmission Revolution Sensor (SP2)
   *5	Rear Planetary Ring Gear	*6	No. 3 Clutch Drum

ATF Temperature Sensor

1. The ATF temperature sensor is installed in the lower valve body for direct detection of the fluid temperature.

2. The ATF temperature sensor is used for the correction of the clutch and brake pressures to maintain a smooth shift quality every time.

   

   Text in Illustration

   *1

   Lower Valve Body

   *2

   ATF Temperature Sensor

Oil Pressure Switch

1. The oil pressure switch is located in the output fluid passage of the shift solenoid valve SL1, and the switch is turned on/off in accordance with the shift solenoid valve output fluid pressure.

2. When shift solenoid valve SL1 malfunctions, the TCM determines the appropriate fail-safe operation to be actuated in accordance with the on/off signals from the oil pressure switch.

   

   Text in Illustration

   *1

   Lower Valve Body

   *2

   Oil Pressure Switch

Park/Neutral Position Switch Assembly, Transmission Control Switch and Shift Paddle Switch

1. The park/neutral position switch assembly sends the P, R, N and D signals to the ECM and TCM.

2. The transmission control switch is installed inside the transmission floor shift assembly to detect the M mode position and inform the ECM.

3. The transmission control switch detects whether the shift lever is in D or M, and detects the operating conditions of the shift lever "+" (forward) or "-" (backward) when M mode is selected, and sends signals to the ECM.

4. The shift paddle switch (transmission shift switch assembly) is installed in the steering wheel. The ECM detects the operation of the shift paddle switch (transmission shift switch assembly) "+" (upshift) or "-" (downshift) when the shift lever is in D or M.

   

Shift Control Mechanism

1. A gate type shift lever that uses a transmission control rod is used.

2. The shift control mechanism consists of a transmission floor shift assembly and a floor shift gear shifting rod sub-assembly.

   

   Text in Illustration

   *1

   Transmission Floor Shift Assembly

   *2

   Floor Shift Gear Shifting Rod Sub-assembly