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One parts site calls it a Drive Plate and another one calls it a Damper Plate but the picture looks like a Clutch Disc to me. And there is a $462 price difference between the two sites. Part #31270 in this picture. http://www.utoyot8.com/Picture.aspx?...ccode=&ppName=
Has anyone ever had to replace this plate/disc? If so, what year is your TCH and at how many miles was the replacement?
Also if anyone can explain when the plate is used, my thoughts are it's how the ICE is started and when the ICE drives the car?
I did a search but don't see many threads about this plate. I'm guessing it's just a low wear part maybe? Thanks
The Toyota HSD replaces a normal geared transmission with an electromechanical system. Because an internal combustion engine (ICE) delivers power best only over a small range of torques and speeds, the crankshaft of the engine is usually attached to an automatic or manual transmission by a clutch or torque converter that allows the driver to adjust the speed and torque that can be delivered by the engine to the torque and speed needed to drive the wheels of the car. When required to classify the transmission type of an HSD vehicle (such as in standard specification lists or for regulatory purposes), Toyota describes HSD-equipped vehicles as having E-CVT (Electronically-controlled Continuously Variable Transmission). [edit] Power sources
High voltage unit of the HSD
In the "standard" car design the alternator (AC generator) and starter (DC motor) are considered accessories that are attached to the internal combustion engine (ICE) which normally drives a transmission to power the wheels propelling the vehicle. A battery is used only to start the car's internal combustion engine and run accessories when the engine is not running. The alternator is used to recharge the battery and run the accessories when the engine is running. HSD replaces the gear box (transmission), alternator and starter motor with a pair of powerful motor-generators[6] (designated MG1 and MG2, ~60 Hp total) with a computerized shunt system to control them, a mechanical power splitter that acts as a second differential, and a battery pack that serves as an energy reservoir. The motor-generator uses power from the battery pack to propel the vehicle at startup and at low speeds or under acceleration. The ICE may or may not be running at startup. When higher speeds, faster acceleration or more power for charging the batteries is needed the ICE is started by the motor-generator (acting as a starter). These features allow the ICE to normally be turned off for traffic stops—accessory power (including air conditioning if needed) is normally provided by the battery pack.
When a moving vehicle operator wants the vehicle to slow down the initial travel of the brake pedal engages the motor-generator(s) into generator mode converting much of the forward motion into electrical current flow which is used to recharge the batteries while slowing down the vehicle. In this way the forward momentum regenerates (or converts) much of the energy used to accelerate the vehicle back into stored electrical energy. (See regenerative braking) Harder braking action engages standard front disk and rear drum brakes which are also provided for faster stops and emergency use. This wastes energy which could have been recovered and is discouraged for normal use. [edit] MG1 and MG2
MG1 (motor generator 1) generates electrical power. MG1 recharges the EV battery and supplies electrical power to drive MG2. In addition, by regulating the amount of electrical power generated (thus varying MG1's internal resistance and rpm), MG1 effectively controls the transaxle's continuously variable transmission. MG1 also serves as the engine starter.[7]
MG2 (motor generator 2) drives the vehicle. MG2 and the engine work together to drive the wheels. The addition of MG2's strong torque characteristics help achieve excellent dynamic performance, including smooth start-off and acceleration. During regenerative braking, MG2 converts kinetic energy into electrical energy, which is then stored in the EV battery.[7]
The mechanical gearing design of the system allows the mechanical power from the ICE to be split three ways: extra torque at the wheels (under constant rotation speed), extra rotation speed at the wheels (under constant torque), and power for an electric generator. A computer program running appropriate actuators controls the systems and directs the power flow from the different engine + motor sources. This power split achieves the benefits of a continuously variable transmission (CVT), except that the torque/speed conversion uses an electric motor rather than a direct mechanical gear train connection. An HSD car cannot operate without the computer, power electronics, battery pack and motor-generators, though in principle it could operate while missing the internal combustion engine. (See: Plug-in hybrid) In practice, HSD equipped cars can be driven a mile or two without gasoline, as an emergency measure to reach a gas station.
An HSD transaxle contains a planetary gear set that adjusts and blends the amount of torque from the engine and motor(s) as it’s needed by the front wheels. It is a sophisticated and complicated combination of gearing, electrical motor-generators and computer controlled electronic controls. One of the motor-generators (MG2 in Toyota manuals; sometimes called "MG-T" for "Torque") is mounted on the drive shaft, and thus couples torque into or out of the drive shafts: feeding electricity into MG2 adds torque at the wheels. The engine end of the drive shaft has a second differential; one leg of this differential is attached to the internal combustion engine and the other leg is attached to a second motor-generator (MG1 in Toyota manuals; sometimes "MG-S" for "Speed"). The differential relates the rotation speed of the wheels to the rotation speeds of the engine and MG1, with MG1 used to absorb the difference between wheel and engine speed. The differential is an epicyclic gear set (also called a "power split device"); that and the two motor-generators are all contained in a single transaxle housing that is bolted to the engine. Special couplings and sensors monitor rotation speed of each shaft and the total torque on the drive shafts, for feedback to the control computer.[8]
I only called it a Clutch Plate because that's what it looks like in the picture (link) in my 1st post. The parts list calls it a Drive Plate or Damper Plate. The picture you posted of the cut away is a great picture and shows where the Drive Plate is between the ICE and E-CVT just like with a standard transmission. But I would imagine the wear and tear on the Drive Plate in the Hybrid is far less than in a standard transmission since there is no clutch pedal and no gears to manually shift through.
Originally I was just doing a search on the E-CVT to see what was inside so I figured a parts list would show that. I was surprised to see the Drive Plate at 1st so it got me wondering if it had to be replaced like a regular clutch in a standard transmission. And I was just wondering how it played a part in running the Hybrid system. Judging by the lack of replies to if anyone has had to replace the Drive Plate, I will assume it's a low maintenance part. Thanks for your help ukrkor.
you welcome. you are just like i am - you like knowing how stuff works.
i have little knowledge on this subject. i do not think there is any equivalent of clutch plate in this setup, for 2 reasons:
1. it's a CVT; sort of; those do not have clutches in a manner we know them.
2. read HSD description one more time. MG1 is mounted directly on the shaft. figures it's basically coupled with engine directly, and is turned on and off, or connects to the shaft and disconnects from it by forces electrical.
what you do want to take into consideration is that folks seriously recommend transmission oil change after 50K miles. it's a splash lubrication setup. like in differential in rear wheel drive vehicle. takes 4 qrts of fresh oil. end users had metal and impurities reported in oil, though it is claimed to be life time product. so, spring time, i'll do mine.
btw, those pictures are fairly old. i think, it's one of their first engine versions. i wouldn't be heavily relying on it.
maybe this will help more:
( i know it's Prius, but principle should be same; no clutches whatsoever hear either)
Conventional "Step" Transmission
A conventional, or "step", transmission, selects from a number of fixed gear ratios between the input side (the engine) and the output side (the drive train to the wheels). In "low" gear, the spin rate of the engine is reduced towards the wheels so that it can power a slow-moving car while spinning fast enough to develop the necessary torque. As the car picks up speed, the spin rate of the engine increases, making a sound we are all familiar with. At some point, depending on how hard he wants to accelerate, the driver, or the transmission itself, shifts to the next higher gear. The engine spin rate drops and then increases again as the car continues to accelerate. In this way, we work our way through the gears, keeping the engine spinning at a rate that delivers the power we need at whatever speed we're traveling and avoiding "over-revving" the engine. As well as reducing spin rate from engine to wheels, a low gear multiplies up the engine torque in the same proportion. This is why acceleration is greater in lower gears and drops off as we (or the transmission) shift to higher gears. To achieve the best acceleration, race car drivers delay upshifting until the engine reaches the "red-line", the spin rate above which it will begin to suffer damage. A car's published 0 to 60 time is measured using a similar strategy and will be much worse if the driver doesn't want to push the engine towards this limit. "True" Continuously Variable Transmission
The more gear ratios we have, the more choices we have in setting the engine spin rate for any given speed. This allows us to call for power when we need it by revving high but to cruise economically by lowering the engine spin rate and reducing losses associated with the fast-moving internal engine parts. A conventional CVT has an infinite (or a very large number) of gear ratios. It selects a ratio that can deliver to the wheels the power being demanded by the driver, but keeps the engine spin rate low within this constraint to improve economy and engine life. You can imagine that as the car picks up speed, the transmission continually shifts into a slightly higher gear. The result is that the pitch of the engine tone stays fairly constant and the acceleration falls off smoothly, instead of in steps, as the higher gear ratios have a smaller multiplying effect on the engine torque. The advantages of a CVT (selection of the best gear ratio at all times to balance performance and economy) are considerably offset by efficiency and reliability problems. Efficient and durable toothed gears, the mainstay of step transmissions, cannot be used. Instead, an arrangement of belts and pulleys is necessary with a mechanism to vary the effective diameter at which the belt passes around the pulley. The Prius Transmission
The Prius transmission produces one of the effects of a CVT but not the other. The spin rate of the engine can be selected to produce the required power but otherwise to spin no faster than is necessary to maintain fuel efficiency. The Prius engine tone therefore sounds as if the car has a CVT because it does not rise as the car picks up speed. Instead, it rises and falls with power demand, in other words, how hard you press on the accelerator pedal. The Prius transmission does not, however, multiply up engine torque at low vehicle speed. This is because it has only one gear ratio. Effectively, the engine is coupled to the wheels as if the car is always in top gear. This would be a crippling limitation, if not for the presence of a powerful electric motor in addition to the gasoline engine. With this motor adding its considerable torque, people have said that the car feels as if it's always in bottom gear! The "Power Split Device"
The central component of the Prius transmission is an epicyclic gear that Toyota calls the "Power Split Device" (PSD). This type of gear is also known as "sun-and-planets" because it consists of a number of "planet" gears surrounding a central "sun" gear. The planet gears are on shafts fixed to a "planet carrier", which revolves around the same axis as the sun. Unlike real planets, they are all the same size and all the same distance from the common center of rotation. The planet gears are surrounded by and mesh with an inside-out gear called the "ring". This also revolves around the same axis as everything else. Click on the diagram at right to get a closer look. The Prius internal combustion engine (ICE) is connected to the planet carrier. As it rotates, the planets mesh with and tend to push both the sun gear (in the middle) and the ring gear (around the outside) in the same direction as the planet carrier. By careful choice of the size (and hence number of teeth) of the sun and ring gears, Toyota has arranged 72% (actually 2.6 divided by 3.6) of the torque to go to the ring and 28% (actually one over 3.6) to go to the sun. This is hard to visualize, so instead think about a straight bar 3.6 feet long being used as a lever. Each end rests on a bathroom scale and you stand 2.6 feet from one end. 72% of the pressure of your weight registers on the closer scale and the remaining 28% registers on the other. The epicyclic gear achieves the same effect with rotational pressure, i.e. torque. Now we understand how the torque of the ICE is split into two directions. The ring gear, which receives the bigger part, is connected via the usual reduction gears to the differential and hence to the wheels. This is how the ICE pushes the car. The sun gear, which receives the smaller part of the torque, is connected to a motor/generator called MG1. For the moment, let's forget than MG1 can act as a motor and imagine it acting as a generator. The ICE driving the planet carrier drives the sun and MG1 spins. A computer adjusts the electrical power drawn from MG1 so that the generation drag balances the torque passed through from the ICE. So, the ICE pushes the car with 72% of its torque and a generator with 28% of its torque. We'll find some use for the generated electricity later. Finally, we have to understand that the ring and the sun, both pushed by the ICE with a fixed fraction of its torque, are free to rotate at different rates. Although there is a fixed mathematical relationship between their spin rates and the ICE spin rate, one can speed up and the other slow down without changing the input spin rate from the ICE. Let's go back to our 3.6 foot lever. Take it off the bathroom scales and have two friends hold an end each. Push the lever 2.6 feet from one end. One friend feels 72% of your push and the other 28%. Now, if you push so hard that they can't stand still, either or both of them can move back and allow you to move forward. They can chose the speed at which they retreat independently of each other. For example, one could stand still and the other do all the retreating. With a short lever, this visualization doesn't take you far from your starting point, but our epicyclic gear works in the same way without limit. If the ring gear stays still, the sun gear can absorb all the rotation of the planet carrier by rotating faster. This is our clue to how the epicyclic gear allows the ICE spin rate to be adjusted like a CVT. For any given road speed, the computer figures out how fast the ring gear is spinning. From the power demand, it decides how fast it would like the ICE to spin. Then it just solves a simple equation to figure out how fast MG1 must spin. Then, it adjusts the power drawn off by MG1 to speed up or slow down the ICE until the desired condition is achieved. None of this affects the fact that 72% of the ICE torque is sent towards the wheels. The wheels can even be stationary and this torque is still applied. By allowing the ICE to drive the car from stationary in this way, we do away with the need for a clutch or torque converter, actually eliminating a wear-prone and bulky component of the transmission. The last step is to find a use for the generated electricity from MG1. A second motor/generator called MG2 is connected to the PSD ring gear and adds its torque to that coming out of the PSD from the ICE (which drives the planet carrier). So, the power that seemed to be going to waste is actually routed around the mechanical PSD by an electrical path and still ends up driving the wheels. In effect, ICE power is split (at the Power Split Device, of course), some following a mechanical path through the ring gear and some following an electrical path to the sun gear, MG1, the control electronics and to MG2. The ring gear and MG2 drive the wheels together through the reduction gears and differential. Although we can gloss over this for now, to fully understand the Prius transmission we need to note that the division of power between the mechanical and electrical paths is not fixed, as the torque split is. Power is the product of torque and spin rate, so the power passing in each direction depends on the relative rates of spin of MG1 and the ring gear. You may see statements to the effect that 72% of the ICE power goes directly to the wheels and 28% is turned into electricity. This is not correct. Torque is split in this ratio, but the power split is variable, a fact that is used to advantage by the engine control computer. Always in Top Gear
We have discovered above how the Prius transmission uses an epicyclic gear, a generator and control electronics to adjust the spin rate of the engine without the use of either a step transmission or a conventional CVT. We also discovered that a fixed proportion (about 72%) of the ICE torque is sent mechanically to the wheels. Without the ability to change the gear ratio between the ICE and the wheels, we cannot multiply up the ICE torque to get high acceleration at low speed. Although we've solved the problem of letting the ICE spin at a suitable rate when the car is moving slowly, the torque coupling is equivalent to always being in top gear! This problem is partly solved already by passing generated electricity from MG1 to MG2 which adds its torque to that of the ICE. Electric motors do not share with an ICE the problem of not generating torque at low speed. In fact, this is where they generate the most torque. If we run the ICE at, say, 2000 r.p.m., with the car barely moving, a lot of power passes from the ICE to MG1. In fact, until the car starts moving, all the power goes to MG1. Even though MG1 gets only 28% of the torque, it gets all of the movement! Since MG2, connected to the wheels, is not rotating very fast, it doesn't take much power to generate its maximum torque. The Prius can launch from a standstill at respectable acceleration up to about 10 m.p.h. using ICE power passing primarily through MG1 and MG2. Only about a fifth of the torque comes directly through the mechanical path during this initial acceleration.
looks like what you are referring to as a Drive Plate housing on the picture is gear housing. planetary and ring gears. nope, PSD is past MG1 towards MG2. either way, i wouldn't be worried about it. worry more about water pumps that go bad right after 50K miles.
What's Missing
The Prius powertrain may look complicated, but we must take into account several things that a conventional car needs that the Prius design has dispensed with. These are:
* there is no "step" gearbox, either manual or automatic - the Prius does not use step gears
* there is no clutch or torque converter - the wheels are always firmly connected by gears to the ICE and motor/generators
* there is no starter motor - the motor/generators start the ICE via the gears in the power split device
* there is no alternator - electrical power is generated by the motor/generators as needed
So, the complexity of the Prius is not actually much greater than a conventional car. In addition, new and unfamiliar parts such as the motor/generators and the PSD are actually likely to have higher reliability and longer service life than some of the parts that have been eliminated.
Wow! I hope there isn't a test at the end of this thread! Great info. Maybe if a Toyota Tech would jump in here and verify why the parts page I posted shows a Drive Plate. From my years of experience being a mechanic, I'm guessing it's a way of starting the ICE since there is no starter. I use to rebuild automatic transmissions so I very familiar with the planetary or PSD and how it works. I like the colored diagram above because it shows what the PSD is connected to and how the drive train works. I now work on electric fork lifts, they have used the Regen technology in their lifts for years now to prolong the battery life between charges. Now AC motors are being used in lifts, very strong and with high torque!
Hybrid is still new to me since I'm a new owner of one. I was holding back on them just watching to see how they hold up. The system is strong and seems reliable enough that even Peterbilt has made a Hybrid truck line. I will be digging into how their system is put together and learning about heavy duty side of Hybrid. http://www.thepetestore.com/walmart-...-peterbilt.php
1. MG1 works as a starter. there is no starter, alternator and clutch as we know them. otherwise, take all the electric stuff out, and it's a regular automatic transmission.
2. all this got me thinking. back in time, on Russian Ladas, which was Fiat, they did not have direct driveshaft to transmission connection. There was a large rubber star shaped piece, that worked as a torque dampener between transmission and driveshaft.
we still have regular ICE, paired with HSD. somehow, i have that feeling, that that housing contains some sort of a similar device. has to have a flywheel in it, as part of ICE then, very likely, some sort of torque dampener. considering that that ICE starts thousands of time a day, no clutch will hold.
btw, HSD is not just a hybrid drive. it is a hybrid hybrid drive. combines two types of hybrid drives into one.
donno. personally, i keep coming across more and more info that Honda's drive is better. smoother. HSD is annoyingly jerky. i'll look into Honda drives some time this year.
Has anyone ever had to replace this plate/disc? If so, what year is your TCH and at how many miles was the replacement?
Also if anyone can explain when the plate is used, my thoughts are it's how the ICE is started and when the ICE drives the car?
I did a search but don't see many threads about this plate. I'm guessing it's just a low wear part maybe? Thanks
The thing looks like a clutch only from the perspective of having the springs to 'smooth out' the power pulses. There is no way to disengage the ICE from the PSD, and the only indication for replacement is if a spring or the disc itself breaks.
IOW, it's there for the life of the vehicle unless the metal in it fatigues and breaks.
1. MG1 works as a starter. there is no starter, alternator and clutch as we know them. otherwise, take all the electric stuff out, and it's a regular automatic transmission.
2. all this got me thinking. back in time, on Russian Ladas, which was Fiat, they did not have direct driveshaft to transmission connection. There was a large rubber star shaped piece, that worked as a torque dampener between transmission and driveshaft.
we still have regular ICE, paired with HSD. somehow, i have that feeling, that that housing contains some sort of a similar device. has to have a flywheel in it, as part of ICE then, very likely, some sort of torque dampener. considering that that ICE starts thousands of time a day, no clutch will hold.
btw, HSD is not just a hybrid drive. it is a hybrid hybrid drive. combines two types of hybrid drives into one.
donno. personally, i keep coming across more and more info that Honda's drive is better. smoother. HSD is annoyingly jerky. i'll look into Honda drives some time this year.
Honda feels more 'conventional' than the HSD. They're both decent solutions to a complex problem - but with different trade-offs. Honda's design keeps a conventional belt-based CVT, which seems to be a 'weak link', or at the very least quite fussy for the fluid quality. Since it spends less time with ICE shut-down, and certainly no time with the electric motor getting the car rolling, you won't feel the 'start-up stumble' the HSD ICE sometimes gets.
The thing I found about start-up roughness is that it's sensitive to oil grade and viscosity. My 2008 was notably rougher on start-up with 5W30 fill the dealer put in for the first change. Smoothed back out with 0W20. My guess is Toyota doesn't 'fire' the engine until oil pressure is detected - thus MG spins it a bit more till it fires.
Has anyone ever had to replace this plate/disc? If so, what year is your TCH and at how many miles was the replacement?
Also if anyone can explain when the plate is used, my thoughts are it's how the ICE is started and when the ICE drives the car?
I did a search but don't see many threads about this plate. I'm guessing it's just a low wear part maybe? Thanks
The thing looks like a clutch only from the perspective of having the springs to 'smooth out' the power pulses. There is no way to disengage the ICE from the PSD, and the only indication for replacement is if a spring or the disc itself breaks.
IOW, it's there for the life of the vehicle unless the metal in it fatigues and breaks.
The thing looks like a clutch only from the perspective of having the springs to 'smooth out' the power pulses. There is no way to disengage the ICE from the PSD, and the only indication for replacement is if a spring or the disc itself breaks.
IOW, it's there for the life of the vehicle unless the metal in it fatigues and breaks.
According to the description of the Drive plate, it uses a dry-type single-plate friction material. Sounds like a one sided clutch plate to me. Where there's friction, there's wear in most situations. See the top of page 4-4 in this link. Also scroll down to figure 4-2, it shows the drive plate in the system. It appears that there is an oil pump in the trans axle too. http://www.autoshop101.com/forms/Hybrid14.pdf
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