Automatic transaxle training tài liệu đào tạo hộp số tự động của KIA

Design Path The average valid oil path to define the inlet and outlet blade angle, radius Torus Section The axis directional section of flow circuit inside of torque converter Impeller T

Automatic Transaxle Basic

Published by Chonan Technical Service Training Center

Contents

1 Fundamentals of automatic transaxle ··· 3.6 Simpson type planetary gear set ···

1.1 General ··· 4 Holding units ···

1.2 PASCAL’s law ··· 4.1 Alpha, Beta Models 1.3 Force and pressure relationship ··· 4.1.1 General information ···

1.4 Pressure On a Confined Fluid ··· 4.1.2 Structure ···

1.5 Force Multiplication ··· 4.1.3 Rear clutch ···

1.6 Piston Travel ··· 4.1.4 Low & reverse brake ···

1.7 Hydraulic System ··· 4.2 HIVEC model ···

1.8 The Fluid Reservoir ··· 4.2.1 Structure ···

1.9 The Pump ··· 4.2.2 Case ···

1.10 Valve Mechanism ··· 4.2.3 Under drive clutch ···

1.11 An Actuating Mechanism ··· 4.2.4 Reverse clutch & Over drive clutch ···

2 Torque Converter ··· 4.2.5 Direct clutch & OWC ···

2.1 Terms for torque converter ··· 4.2.6 Reduction brake ···

2.2 Connection with oil pump ··· 4.3 F4AEL-K model ···

2.3 Three elements of torque converter ··· 4.3.1 Structure ···

2.4 Torque converter pump impeller ··· 4.3.2 Clutches ···

2.5 Turbine ··· 4.3.3 2-4 brake ···

2.6 Stator assembly ··· 4.3.4 Low & reverse brake ···

2.7 Stator Action within the T/C ··· 4.4 FRA (JATCO) model ···

2.8 Fluid Flow at Coupling Stage ··· 4.4.1 Structure ···

2.9 Torque converter performance ··· 4.4.2 Functions ···

2.10 Optimal design of torque converter ··· 4.5 AISIN models ···

2.11 Lock-up converters ··· 4.5.1 Overhauled parts ···

2.12 Fluid Couplings All slip a Little ··· 4.5.2 Oil pump ···

2.13 Piston Locks Turbine to Impeller ··· 4.5.3 Over drive clutch ···

2.14 Damper springs ··· 4.5.4 Input shaft & O/D planetary gear ···

2.15 ATF(Automatic Transaxle Fluid) ··· 4.5.5 O/D OWC & Forward clutch ···

3 Planetary gear ··· 4.5.6 Direct clutch ···

3.1 General ··· 4.5.7 Front planetary gear ···

3.2 Operation ··· 4.5.8 Direct clutch and forward clutch ···

3.3 Direction of travel ··· 4.5.9 Rear planetary gear & 2 nd brake ···

3.4 Gear ratios ··· 4.5.10 Overdrive brake ···

3.5 Ravigneaux type planetary gear set ··· 4.5.11 Low & reverse brake ···

5 Power flow ··· 7.5 Reducing valve ···

5.1 Alpha, Beta models ··· 7.6 Torque converter control valve ···

5.1.1 General information ··· 7.7 Damper clutch control valve ···

5.1.2 Power flow ··· 7.8 Damper clutch control solenoid valve ···

5.2 HIVEC model ··· 7.9 Throttle valve/Kick-down valve ···

5.2.1 Operating element chart ··· 7.10 Governor ···

5.2.2 Power flow ··· 7.11 1-2 shift valve ···

5.3 F4AEL-K model ··· 7.12 2-3 shift valve ···

5.3.1 Gear train ··· 7.13 N-D, N-R accumulator valve ···

5.3.2 Operating element chart ··· 7.14 Accumulator ···

5.3.3 Power flow ···

5.4 FRA (JATCO) model ···

5.4.1 Operating element chart ···

5.4.2 Power flow ···

5.5 AISIN models ···

5.5.1 Structure ···

5.5.2 Function ···

5.5.3 Operating element chart ···

5.5.4 Power flow ···

6 The test on the vehicle ···

6.1 General information ···

6.2 Neutral and parking ···

6.3 Drive (All stages of operation) ···

6.4 Checking for slippage ···

6.5 Gear, planetary gear and bearing noise ···

7 Hydraulic control ···

7.1 General information ···

7.2 Manual valve ···

7.3 Regulator valve ···

7.4 Line relief valve ···

APPENDIX ···

Transaxle identification ···

Product line-up ···

Variation of electronic solenoid valves ···

Unit conversion table ···

1 Fundamentals of automatic transaxle

1.1 General

To investigate the hydraulic systems of the transaxle is a basic fundamental to understand its

system These systems or circuits are very important for correct operation of the transaxle Without

the hydraulic circuits present in the transaxle, none of the components could combine to produce

motion, nor could the transaxle function automatically

The transaxle is lubricated, cooled, shifted and connected to the engine by means of a fluid

Without hydraulic oil in the transaxle, none of these tasks could be performed satisfactorily

Therefore, it is imperative to learn the basics of hydraulic fundamentals before clutch and band

application or hydraulic charts can be investigated thoroughly 90% of all automatic transaxle

failures can be diagnosed using hydraulic charts If the understanding of hydraulic fundamentals is

not complete, then these charts would be of little value to the service technician

1.2 PASCAL’s Law

In the early seventeenth century, Pascal, a French scientist, discovered the hydraulic lever

Through controlled laboratory experiments, he proved that force and motion could be transferred by

means of a confined liquid Further experimentation with weights and pistons of varying size, Pascal

also found that mechanical advantage or force multiplication could be obtained in a hydraulic pressure

system, and that the relationships between force and distance were exactly the same as with a

mechanical lever

From the laboratory data that Pascal collected, he formulated Pascal’s Law, which states :

“Pressure on a confined fluid is transmitted equally in all directions and acts with equal force on equal

areas.” This law is a little complex to completely understand as it stands right now The following

illustrations and explanations break down each concept and discuss them thoroughly enough for easy

understanding and retention

1.3 Force and Pressure Relationships

- Force

A simplified definition of the term force is : the push or pull exerted on an object There are two

major kinds of forces : friction and gravity The force of gravity is nothing more than the mass, or

weight of an object In other words, if a steel block weighing 100 kg is sitting on the floor, then it is

exerting a downward force of 100 kg on the floor

The force of friction is present when two objects attempt to move against one another If the same

100 kg block were slid across the floor, there is a dragging feeling involved This feeling is the force

of friction between the block and the floor When concerned with hydraulic valves, a third force is

also involved This force is called spring force Spring force is the force a spring produces when it

is compressed or stretched The common unit used to measure this or any force is the kilogram (kg),

or a division of the kilogram such as the gram (g)

- Pressure

Pressure is nothing more than force (kg) divided by area (m2), or force per unit area Given the

same 100kg block used above and an area of 10m2 on the floor ; the pressure exerted by the block

is : 100kg/10m2 or 10kg per square meter

1.4 Pressure On a Confined Fluid

Pressure is exerted on a confined fluid by applying a force to some given area in contact with the

fluid A good example of this would be if a cylinder is filled with a fluid, and a piston is closely fitted to

the cylinder wall having a force applied to it, thus, pressure will be developed in the fluid Of course,

no pressure will be created if the fluid is not confined It will simply “leak” past the piston There

must be a resistance to flow in order to create pressure Piston sealing, therefore, is extremely

important in hydraulic operation The force exerted is downward (gravity) ; although, the principle

remains the same no matter which direction is taken

The pressure created in the fluid is equal to the force applied ; divided by the piston area If the

force is 100 kg, and the piston area is 10m2, then pressure created equals 10kg/m2 = 100kg/10m2

Another interpretation of Pascal’s Law is that : “Pressure on a confined fluid is transmitted

undiminished in all directions.” Regardless of container shape or size, the pressure will be

maintained throughout, as long as the fluid is confined In other words, the pressure in the fluid is

the same everywhere

The pressure at the top near the piston is exactly same as it is at the bottom of the container, thus,

the pressure at the sides of the container is exactly the same as at top and bottom

1.5 Force Multiplication

Going back to the previous figure and using the 10kg/m2 created in the illustration, a force of

1,000kg can be moved with another force of only 100kg The secret of force multiplication in

hydraulic systems is the total fluid contact area employed The figure shows an area that is ten

times larger than the original area The pressure created with the smaller 100kg input is 10kg/m2

The concept “Pressure is the same everywhere”, means that the pressure underneath the larger

piston is also 10 kg/m2 Reverting back to the formula used before : Pressure = Force/Area or P =

F/A, and by means of simple algebra, the output force may be found

Example : 10kg/m2 = F(kg) / 100m2 This concept is extremely important as it is used in the

actual design and operation of all shift valves and limiting valves in the valve body of the transaxle It

is nothing more than using a difference of area to create a difference in pressure in order to move an

object

1.6 Piston Travel

Returning to the small and large piston area discussion The relationship with a mechanical lever

is the same, only with a lever it’s a weight-to-distance output rather a pressure-to-area output

Referring to following figure, using the same forces and areas as in the previous example ; it is shown

that the smaller piston has to move ten times the distance required to move the larger piston 1m

Therefore, for every meter the larger piston moves, the smaller one moves ten meters This principle

is true in other instances, also

A common garage floor jack is a good example To raise a car weighing 1,000kg, an effort of only

25kg may be required But for every meter the car moves upward, the jack handle move many times

that distance downward

A hydraulic ram is another good example where total input distance will be greater than the total

output distance The forces required in each case are reversed That is, very little effort is required

to produce a greater effort

1.7 Hydraulic System

Now that some of the basic principles of hydraulics have been covered and understood, it is time to

explore hydraulic systems and see how they work Every pressure type hydraulic system has certain

basic components This discussion will center on what these components are and what their

function is in the system Later on, the actual systems in the transaxle will be covered in detail

The figure reveals a basic hydraulic system that can be used in almost any situation requiring work to

be performed The basic components in this system are : Reservoir, Pump, Valving, Pressure lines,

Actuating mechanism or mechanisms

1.8 The Fluid Reservoir

Since almost all fluids are nearly incompressible, the hydraulic system needs fluid to function

correctly The reservoir or sump, as it is sometimes called, is a storehouse for the fluid until it is

needed in the system In some systems, (also in the automatic transaxle), where there is a constant

circulation of the fluid, the reservoir also aids in cooling of the fluid by heat transfer to the outside air

by way of the housing or pan that contains the fluid The reservoir is actually a fluid source for the

hydraulic system The reservoir has a vent line, pressure line, and a return line In order for the oil

pump to operate correctly, the fluid must be pushed up from the reservoir to the pump

The purpose of the vent line is to allow atmospheric pressure to enter the reservoir As the pump

rotates, an area of low pressure results from the pump down to the reservoir via the pressure line

The atmospheric pressure will then push the oil or fluid up to the pump due to a pressure difference

existing in the system

The return line is important because with a system that is constantly operating, the fluid has to be

returned to the reservoir for re-circulation through the system

1.9 The Pump

The pump creates flow and applies

force to the fluid Remember flow is

needed to create pressure in the system

The pump only creates flow If the flow

doesn’t meet any resistance, it’s referred

to as free flow, and there is no pressure

built up There must be resistance to

flow in order to create pressure

Pumps can be the reciprocating piston

type (as in a brake master cylinder) or,

they can be of the rotary type The figure

shows three major types of hydraulic oil

pumps employing the rotary design The

internal-external type of pump design is

used almost exclusively in today’s

automatic transaxle

1.10 Valve Mechanism

After the pump has started to pump the oil,

the system needs some sort of valving, which

will direct and regulates the fluid Some

valves interconnect passages, directing the

fluid where to go and when On the other

hand, other valves control or regulate

pressure and flow The pump will pump oil to

capacity all the time It is up to the valves to

regulate the flow and pressure in the system

One important principle to learn about valves

in automatic transaxle hydraulics is that the

valves can move in one direction or the other

in a passage, opening or closing another

passage

The valve may either move left or right, according to which force can overcome the other When

the spring force is greater than the hydraulic force, the valve is pushed to the left, closing the passage When the hydraulic force builds up enough force to overcome the spring force, the hydraulic force will

push the valve to the right compressing the spring even more, and re-directing the fluid up into the

passage When there is a loss of pressure due to the re-direction of oil, the spring force will close

the passage again This system is called a balanced valve system A valve that only opens and

closes passages or circuits, is called a relay valve

1.11 An Actuating Mechanism

Once the fluid has passed through the

lines, valves, pump, etc., it will end up at the

actuating mechanism This is the point

where the hydraulic force will push a piston

causing the piston to do some sort of

mechanical work This mechanism is

actually the dead end that the oil pump flow

will finally encounter in the system This

dead end causes the pressure to build up in

the system

The pressure works against some surface

area (piston) and causes a force to be

applied In hydraulics and transaxle

technology, the actuating mechanism is also

termed a servo

A servo is any device where an energy

transformation takes place causing work as

a result The clutch assemblies found in

the alpha automatic transaxle are actually

servos, but they are termed “clutch” for ease

of identification

2 Torque Converter

2.1 Terms for torque converter

Element A factor has a function to multiply and transmit the power by oil flows

(Impeller, Turbine, Reactor (Stator): 3 Elements) Stage The number of turbine (output element)

Phase The number of functional change inside torque converter

Max DIA of

Flow Path

The factor effects the capacity of torque converter (Φ230, Φ240 )

Design Path The average valid oil path to define the inlet and outlet blade angle, radius

Torus Section The axis directional section of flow circuit inside of torque converter

Impeller The power input element (usually it called "pump")

Turbine The power output element

Stator The reacting element (It determines the capacity of OWC)

Shell The most outer wall of torus section

Core The most inner wall of torus section

Max DIA ofFlow Path

Just like manual transmission cars, cars with automatic transmissions need a way to let the engine

turn while the wheels and gears in the transmission come to a stop Manual transmission cars use a

clutch, which completely disconnects the engine from the transmission Automatic transmission cars

use a torque converter A torque converter is a type of fluid coupling, which allows the engine to

spin somewhat independently of the transmission If the engine is turning slowly, such as when the

car is idling at a stoplight, the amount of torque passed through the torque converter is very small, so

keeping the car still requires only a light pressure on the brake pedal

If you were to step on the gas pedal while the car is stopped, you would have to press harder on the

brake to keep the car from moving This is because when you step on the gas, the engine speeds up

and pumps more fluid into the torque converter, causing more torque to be transmitted to the wheels

In addition to the very important job of allowing your car come to a complete stop without stalling

the engine, the torque converter actually gives your car more torque when you accelerate out of a

stop Modern torque converters can multiply the torque of the engine by two to three times This effect

only happens when the engine is turning much faster than the transmission

At higher speeds, the transmission catches up to the engine, eventually moving at almost the same

speed Ideally, though, the transmission would move at exactly the same speed as the engine,

because this difference in speed wastes power This is part of the reason why cars with automatic

transmissions get worse gas mileage than cars with manual transmissions To counter this effect,

some cars have a torque converter with a lockup clutch When the two halves of the torque converter

get up to speed, this clutch locks them together, eliminating the slippage and improving efficiency

2.2 Connection with Oil Pump

2.3 Three Elements of Torque Converter

The three elements torque converter consists

of an impeller, turbine and a stator assembly

The impeller is an integral part of the torque

converter housing which also encloses the

turbine and the stator The turbine is splined to

the transaxle input shaft

The stator assembly incorporates one-way

clutch that is splined to an extension of the front

pump housing This extension is termed the

reaction shaft

2.4 Torque Converter Pump Impeller

2.5 Turbine

The turbine is the driven, or output, member

of the converter The design of the turbine is

similar to that of the impeller except that the

turbine blades are curved in the opposite

direction to the impeller blades

Fluid from the impeller strikes the turbine

blades and causes the turbine to rotate along

with the impeller, thus turning the input shaft of

the transaxle in the same direction as that of

the engine crankshaft

2.6 Stator Assembly

The fluid leaving the turbine returns to the impeller by a third set of blades known as the stator

assembly The stator is mounted on a stationary shaft that is an integral part of the oil pump

The one-way clutch permits the stator to rotate only in the same direction as the impeller The

clutch locks the stator to the shaft in order to provide the torque multiplication effect

2.7 Stator Action within the Torque Converter

When the vehicle stationary, the turbine is also stationary As the engine begins to rotate, the oil is

thrown into the turbine from the impeller with a great amount of force; due to the speed differential

between the two members

The tendency for a bounce-back effect exists, as explained before With this condition, the oil is

leaving the trailing edges of the turbine vanes in a “hindering” direction That is, if it’s direction were

not changed before it entered the impeller, it would tend to slow the impeller down Under stall

conditions, the oil strikes the faces of the stator vanes and tries to turn the stator opposite engine

rotation The one-way clutch locks up and holds the stator stationary Now, as the oil strikes the

stator vanes, it is turned in a “helping” direction before it enters the impeller This circulation from

impeller to turbine, turbine to stator, and stator back to impeller can produce a maximum torque

multiplication of roughly 2.17:1

As vehicle speed increases, turbine speed approaches impeller speed and the torque multiplication

drops off 1:1 At this point, the oil begins to strike the backs of the stator vanes This causes the

stator to start freewheeling, or to overrun

In effect, the stator gets out of the way of the oil and thereby no longer enters into the torque

converter action The converter then acts like a fluid coupling

2.8 Fluid Flow at Coupling Stage

As the turbine speed increases to match the impeller, or engine speed, most of the oil that had

been in violent vortex, and rotary flow, is not at the outside portion of both members There is still

both rotary and vortex flow occurring in the torque converter, but it’s a very limited amount It is at

this point that the stator is overrunning and the converter is actually a fluid coupling The activity that

took place at stall has decreased immensely at a cruising speed (approximately 20km/h (12mph) and

up) where this coupling stage occurs

There are two kinds of flows inside of torque converter depends on its speed and phase

- Vortex Flow (Circulation Velocity): The circulation flow inside of blades due to the centrifugal

force from the impeller

- Rotary flow: The oil confined inside of blades flows toward impeller rotating direction

[The flows of vortex or rotary]

[The impeller vortex flow]

Those two kinds of flows (vortex and rotary) can be analyzed by vector diagram as follows

[The vector diagram of vortex and rotary flow]

[The vector diagram depends on the velocity ratio ‘e’ ]

[The flows depends on the velocity ratio ‘e’]

2.9 Torque converter performance

Capacity factor (Cf) : The capacity of torque converter

Cf = Ti / Ni2 (Ti : Input torque, Ni : Input RPM)

Torque ratio (Tr)

Tr = To / Ti (Ti : Input torque, To : Output torque)

Velocity ratio (e)

e = No / Ni (No : Output RPM, Ni : Input RPM)

Efficiency (η)

η = Tr X e (Tr : Torque ratio, e : Velocity ratio)

2.10 Optimal design (selection) of torque converter

When the automotive designer selects the torque converter, the stall rpm of torque converter should

be positioned between 2,000rpm to 2,600rpm under the condition of wide-open throttle If the stall

rpm is out of above zone, there are some demerits as follows

- In case of 2,000 rpm or less: Capacity factor (Cf) is high (Because input torque is high but

input rpm is low) In this case, the fuel consumption at engine idle condition is poor and the

foot braking effort will be high at idle situation because of higher input torque

- In case of 2,600 rpm or more : Capacity factor (Cf) is low (Because input torque is low but

input rpm is high) In this case, the overall fuel consumption will be poor and it will result in

higher engine noise

Gear-ratio-to-engine match up is critical in automatic transaxles We defined stall speed as the

impeller speed(rpm’s) when maximum torque multiplication is produced To provide maximum

torque to the drive wheels, we would like stall speed to be the same as the speed of the engine when

it produces maximum torque Maximum engine torque rpm’s should match torque converter stall

speed rpm’s for optimum performance If the torque converter is too large or too small for the

application, driving performance may be seriously degraded If the converter is too low a capacity for

the engine, the engine will run at a higher than optimum rpm when transmitting maximum torque If

the converter is too large, too high a capacity for the engine, the engine won’t be able to drive the

impeller to the maximum torque point

The normal practice is to match stall speed and peak torque engine rpm’s The massage is that

field mechanics should not try to alter the converter-engine size match up engineered by the

manufacturer

2.11 Lock-Up Converters

The idea of the lock-up torque converter is not new - it’s has been around for a number of years

Benefits of the lock-up system are threefold:

1 Better fuel economy

2 Lower transmission operating temperature during highway operation

3 Less engine speed during highway operation

The lock-up feature has been added with no loss whatsoever in the normal smooth operation of the

transaxle, in fact, most car drivers will not be aware of the lock-up action at all

2.12 Fluid Couplings All slip a Little

Although fluid couplings provides smooth, shock-free power and torque transfer, it is natural for all

fluid drives to slip somewhat, even in drive

The lock-up clutch improves fuel economy by eliminating torque converter slip in direct gear above a

predetermined speed

With a conventional converter in direct drive, both the impeller and the turbine are rotating at

approximately the same speed The stator is freewheeling, and no torque multiplication is produced

or needed If we can now lock the turbine and the impeller together, we can achieve a condition of

zero slippage in direct drive

2.13 Piston Locks Turbine to Impeller

A moveable piston was added to the turbine, and friction material was added to the inside of the

impeller housing Now, by means of oil pressure, the turbine piston can be forced against the

impeller friction material resulting in total converter lock-up

[The torque converter clutch has a force of approximately 800pounds when applied This value is

less than that of a manual transmission clutch, because the lock-up clutch applies only in direct drive

with the vehicle in motion This is a much lower load than the required to engage a manual

transmission from a dead stop A greater force is not required to lock together the two members of

the torque converter with the vehicle at speed.]

The result is a straight-through 1:1 mechanical connection of the engine and transmission plus the

elimination of all hydraulic fluid slippage in direct drive

2.14 Damper Springs

Since the locked-up mode has eliminated the vibration damping effect of the conventional fluid

coupling, any torsion vibration load transmitted by the engine is now absorbed by eight damper

springs between the lock-up piston and the turbine

The lock-up mode is activated only in direct drive Even though there is some hydraulic slippage in

all gears, the lock-up feature cannot not be applied in low and second gears because lock-up

eliminates the torque multiplication necessary for acceleration This means lock-up only occurs after

the 2-3 up shift

[Lock-up could occur in lower gears if the *failsafe valve sticks Up shifts would be harsher than

normal, and there would be a loss of performance in lower gears due to the loss of torque

multiplication in the torque converter]

* Fail-safe valve: Damper clutch control solenoid valve

2.15 ATF (Automatic Transaxle Fluid)

When new, ATF (Automatic Transaxle Fluid) should be red The 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

• The fluid smells burnt

Metal particles can be seen or felt on the dipstick

- ATF Temperature VS Oil Level

Ravigneaux (Double pinion) type

3 Planetary Gear

3.1 General

Planetary gear sets can provide a wide range of gear ratios and combinations of gear ratios One

simple planetary gear set produce as many as seven gear ratios, two of these within rotation direction

reversal The simplest planetary gear set includes three members as shown in below figure

- A sun gear at the center of the system

- A planet carrier with at least three planet pinion gears those are free to rotate on their own

shafts The planet pinions rotate around and mesh with the sun gear and the annulus gear

- An internal annulus gear, sometimes called a ring gear, that rotates around the outside of the

planet pinions and meshes with them

All automatic transmissions use planetary gears Most will look much more complex than this

simple gear set An understanding of this example, though, will enable you to understand and

analyze more complicated gearing later The principles we talk about in this section apply equally to

the example gear set and to the more complex planetary gears you will find in Hyundai/Kia transaxle

3.2 Operation

All planetary gear sets are operated by holding one member stationary, using another as an input,

and using the third as an output If no member is held stationary, the gears are all able to freewheel,

and no power is transmitted If you think about it, you will discover that there are six ways you can

operate the gear set You can hold each of the members’ stationary, use one of the remaining two

for input, and use the other for output The combinations, or conditions, result in variations in

Simpson (Single pinion) type

direction of travel and of gear ratios

While Hyundai/Kia automatic transaxles may not use all of these gear ratio conditions, it is

important to understand all six in order to fully understand the power flow through the transaxles you

work with

3.3 Direction of travel

As can be seen from the previous figure (Planetary gear set), the annulus gear, being internally

toothed, rotates in the same direction as the planetary gears, and the opposite direction s the sun

gear No matter which of the six conditions we operate the gears in this relationship holds If the

planetary carrier is held stationary, input and output rotation will always be in opposite directions

Holding the planet carrier stationary is used to obtain reverse gear In all other cases, input and

output rotate in the same direction

3.4 Gear ratios

Sun, annulus and planet gears are designed with certain pitch diameters to produce desired gear

ratios The gear ratios we show for the figures in this chapter are just examples However, the

basic relationships are always the same

For instance, if we hold the sun gear stationary, use the planet carrier for input and the annulus gear

for output, it will always result in torque reduction and speed increase, although the amount of each

may differ from the example These constant relationships are shown in below chart

The following descriptions of conditions all refer to this chart All six use the same set of gears, allow

ing a comparison of gear ratios for various conditions

Annulus

Results Torque

reduction

Torque increase

Torque increase

Torque reduction

Torque reduction

Torque increase Direction Forward Forward Forward Forward Backward Backward

- Conditions #1 and #2: sun gear held

Conditions #1 and #2 are both with the sun gear held stationary Diagrams of conditions #1 and

#2 are shown in below figures In condition #1, the planet carrier is the input and the annulus gear is

the output The input-to-output ratio is 0.7:1, providing an increase in speed and a reduction in

torque Any ratio, such as this one, where the first number is smaller than 1.0 provides an increase

in rotational speed and a decrease in torque

On the other hand, a ratio where the first number is larger than 1.0 indicates an increase in torque

and a reduction in rotational speed

With the input and output exchanged as in below figure, the annulus gear as input and the planet

carrier as the output, the result is exactly the opposite, as you might expect There is an increase in

torque and a reduction in speed The input-to-output gear ratio is the reciprocal of the ratio on

condition #1, 1.45:1

Input

OutputStationary

Stationary

InputOutput

- Conditions #3 and #4: annulus gear held

In condition #3 and #4, the annulus gear is held stationary Diagrams of conditions #3 and #4 are

shown in below figures In condition #3, the sun gear is the input and the planet carrier is the output

The input-to-output ratio is3.23:1, the highest torque output of any of the six conditions, and so the

greatest speed reduction

Exchange the input and output as in below figure, make the planet carrier the input and the sun

gear the output, and again the result is the opposite, lower torque and higher speed This condition

provides the greatest speed and lowest torque output of the six, with an input-to-output ratio of 0.32:1,

the reciprocal of the condition #3 ratio

Input

Stationary Output

Output

Stationary Input

- Conditions #5 and #6: Planet carrier held

In conditions #5 and #6, the planet carrier is held stationary Conditions #5 and #6 are shown in

below figures Since the two rotating members are the annulus gear and the sun gear, the output

direction of rotation is the reverse of the input for both conditions With the annulus gear as the input

and the sun gear as the output as in below figure, the input-to-output ratio is 0.45:1, producing an

increase in speed and a reduction in torque

With condition #5 input and output reversed as in below figure, the sun gear is the input and the

annulus gear is the output The input-to-output ratio is 2.10:1, making this a low speed, high torque

condition, well suited for a reverse gear range in a transaxle There are seven gear ratios to be

derived from a simple planetary gear set The seventh gear ratio is direct drive, and results when

any two of the three members of a gear set are locked together When two members are rotating at

the same speed in the same direction, the effect is the same as lockup In this condition, the

input-to-output ratio is 1.0:1, a direct drive condition Input and output speed are equal, as are input and

output torque

Output

Input Stationary

Input

Output Stationary

3.5 Ravigneaux type planetary gear set

The Ravigneaux type plnetary gear set consists of two sun gears, each meshing with one of two sets

of planetary pinion gears in a single carrier, and a single annulus gear that meshes with one of the

sets of pinions The two sun gears are called the forward and the reverse sun gears, for the gear

conditions they operate in Power input is to either of these two sun gears Power output is through

the annulus gear, which has the parking sprag on the outer circumstance Various holding elements

are built into gear set components

[Ravigneaux type planetary gear set]

- Ravigneaux type planetary gear ratio

The Ravigneaux type planetary gear has double pinion gears for the gear ratio increasing and it is

applied in the Alpha, KM series and F4AEL-K model

1) In the basis of point C, the rotating direction of FSG and RSG are opposite

Also AG and RSG are opposite direction

2) Distance from point C

Distance A - C: The ratio of forward sun gear teeth

Distance A - B: The ratio of annulus gear teeth

Distance A - D: The ratio of reverse sun gear teeth

3) If the dot line is positioned above line A-D, it means forward rotating direction In case of lower,

it means forward direction Also if is positioned on the line A-D, it is a stopping state

Parking sprag

Long pinion

Reverse sun gear

Forward sun gear

Output flange

Annulus gear Short pinion One-way clutch

Planetary carrier

4) Point B, annulus gear means output of rotation

- 1 st Gear

1st gear operating elements : R/C (FSG), OWC (Carrier)

1) Point C should be positioned on the line A-D, because OWC fixes the carrier

2) FSG rotates in amount of distance from A to A’

3) At this time AG rotates in amount of distance from B to B’

4) RSG rotates with opposite direction comparing with FSG

5) Using the triangle equation,

B (AG)

C (Carrier)

D (RSG)1/74 1/34 1/26

B’

- 2 nd Gear

2nd gear operating elements: R/C (FSG), K/D (RSG)

1) Point D should be positioned on the line A-D, because K/D fixes the RSG

2) FSG rotates in amount of distance from A to A’

3) At this time AG rotates in amount of distance from B to B’

4) Using the triangle equation,

1/26

X

11/74

X : 1 = 1/26 : 1/74 X=2.846

1/34

X : (1/26+1/34) = 1 : (1/74+1/34)

X=1.581

- 4 th Gear (Overdrive)

4th gear operating elements: E/C (Carrier), K/D (RSG)

1) Point D should be positioned on the line A-D, because K/D fixes the RSG

2) Carrier rotates in amount of distance from C to C’

3) At this time AG rotates in amount of distance from B to B’

4) Using the triangle equation,

1/74

1/34

1 : (1/74+1/34) = X : 1/34

X=0.685

- Reverse Gear

Reverse gear operating elements: F/C (RSG), L&R brake (Carrier)

1) Point C should be positioned on the line A-D, because L&R brake fixes the Carrier

2) RSG rotates in amount of distance from D to D’

3) At this time AG rotates in amount of distance from B to B’

4) Using the triangle equation,

3.6 Simpson type planetary gear set

Simpson type planetary gear set has characteristics as follows

- Single pinion was applied to increase the gear ratio In almost cases, two planetary gear sets are

equipped in case of 4-speed automatic transaxle One is overdrive planetary gear and the other

one is output planetary gear Depends on the structure, one more single planetary gear set is

added even though 4-speed automatic transaxle, that is ‘AISIN’ rear driving transmission

- Overall rotating speed of sun gear is lower than one of Ravigneaux type planetary gear because it’s

speed is dispersed due to the double or triple units of planetary gear sets comparing with the just

one unit of double Ravigneaux type planetary gear

Under drive sun gear Reverse sun gear

- Simpson type planetary gear ratio

The Simpson type planetary gear has single pinion gear for the gear ratio increasing and it is

applied in the HIVEC and FRA (JATCO) model

S1: Front Sun gear (e.g = 28), C1 : Front carrier

S2: Rear Sun gear (e.g = 35), C2 : Rear carrier

R1: Front ring gear (e.g = 74)

R2: Rear ring gear (e.g = 67)

S1 1

- 1 st Gear

R1 is fixed by Low clutch (Under drive clutch)

C2 is fixed by OWC R1 (C2) point becomes zero

- 4 th Gear

S2 is fixed by 2-4 brake (2nd brake) S2 point becomes zero

4th Gear ratio = (74/28) / (74/28 + 1) = 0.72549

- Reverse gear

R1 is fixed by LR brake (LR brake)

C2 is fixed by Reverse clutch (Reverse clutch) R1 (C2) point becomes zero

Reverse Gear ratio = (74/28) / 1 = 2.642857

Idler gear

4 Holding units

4.1 Alpha, Beta Models (Including KM series)

4.1.1 General Information

[KM series: W-E type] [Alpha, Beta: E-W type]

For a vehicle to move forward, it should be considered the rotating direction of final output

shaft of transaxle In case of KM series, the transaxle is located at the left side of the engine

when you open the hood so it is required to install an idler gear inside of transaxle to change

the final rotating direction, what is called ‘West-East array type’

On the other hand, alpha and beta automatic transaxle including current designed front

driving transaxle, not necessary to add an idle gear, the transaxle is located at the right side

of the engine, what is called ‘East-West array type’

Seven holding units control the flow of power through the transaxle: three multiple disc clutch

assemblies, two one-way clutches, the kick-down band, and the damper clutch All but one

of the units hold and connect various elements of the transaxle to provide forward and reverse

gear ratios from input to output of the gear set The remaining unit, a one-way clutch in the

torque converter, locks up the torque converter stator to provide increased torque

In the respect of the total usages of shaft inside of transaxle, it can be classified into 2-axis type and

3-axis type 3-axis type has one more axis due to the idler gear, it allows to change the rotating

direction for forward driving So W-E array type has three axis and E-W array type has two axis

respectively

- Multiple disc clutches

All three multiple disc clutches are similar, at least in operating principle, and all are hydraulically

actuated The clutch shown in below figure is the front clutch that used in alpha, beta transaxle

including of KM series, but it is typical of all three used in current designed automatic transaxle It is

an exploded view of the front clutch assembly, showing the component parts of the front clutch

These include the retainer, piston, return spring, clutch plates and discs, and various seals and

retaining rings

[Front clutch assembly]

- Clutch pack

The stack of alternating steel clutch plates and friction-material-lined clutch discs in the clutch

assembly is called the clutch pack The last clutch plate in the pack is much thicker than the others,

and is called a pressure plate The clutch plates and pressure plate are lugged on the outside

diameter The lugs fit into groves in the piston retainer, so the plates and the piston retainer rotate

together The clutch discs are steel, but are lined on both sides with friction material Clutch discs

are internally splined, and driven by the hub of the clutch retainer In exploded views of the three

clutches, you’ll see the individual components that make up each clutch pack, and see the differences

between clutch packs in the three clutches

The front clutch is actuated when the transaxle is in either third or reverse gear Hydraulic pressure

is applied to the piston When this pressure overcomes spring pressure, the piston forces the discs

and plates into contact When engaged, the front clutch connects the input shaft to the reverse sun

gear

Pulse generator-B

4.1.2 Structure

[Advance alpha – A4AF3 Model]

For more information, refer the

‘A/T (FF) Alpha & Beta’ training guide book

4.1.3 Rear clutch

[Rear clutch assembly]

The rear clutch is engaged in all forward gears, and connects the input shaft to the forward sun

gear When both the front and rear clutches are engaged, both sun gears rotate at the same speed,

locking up the gear set and providing a 1:1, direct drive gear ratio

4.1.4 Low & reverse brake