A Subaru with a Toyota Hybrid System

Hello, I'm Professor John Kelly, and  this is the WeberAuto YouTube channel.   Today we are going to do something a little  different than the traditional videos that I've   put out over the last couple years on electric  vehicles today we're going to look at the hybrid   vehicles that Subaru has produced and I have two  of them that have been donated from Subaru of   America to our automotive technology program and  I want to thank Subaru for that we use these all   the time and the first one is is right behind me  here that is a 2016 Subaru Crosstrek Hybrid and   it is a parallel hybrid and this other one right  here behind me is a 2019 Subaru Crosstrek plug-in   hybrid and so it has an electric-only driving  mode where you can drive so many miles and   then it switches to a hybrid operation and what's  interesting to me or what was real interesting to   me when we received these vehicles is the overall  hybrid operation the 2016 back here as I mentioned   is a parallel hybrid and I'll make another video  about how that system works today we're going   to concentrate on this plug-in hybrid and this  hybrid vehicle was announced by Subaru is coming   in May of 2018 as a 2019 model year vehicle and an  interesting thing in the press release from Subaru   states that it is this new hybrid system  and all kinds of stuff about it but one thing   that caught my eye was an all-new transmission  and the Toyota hybrid system, I thought wow a   Toyota hybrid system in a Subaru I have heard  that Toyota owns a portion of Subaru and so it   makes sense that there would be this cooperation  between them and so I wanted to see I want to   see inside this transmission and so I looked and  looked and looked and we we had this car donated   to us a year ago and I looked on eBay I looked  in salvage yards I couldn't find a transmission   and so I did a saved search and finally got one  off of eBay and was real excited tore it apart   or disassembled it I should say I don't  tear things apart and I want to show you   this transmission it is really cool this is a  cool car this is an all-wheel drive mechanical   all-wheel drive but it is driven through  electric motors unlike some other vehicles   that have an electric only rear axle this has a  physical rear axle with a drive shaft going to it   so let's take a look at what is unique  about this Toyota hybrid system transmission   and explore it so the first thing we're going  to do is go look at just a regular Toyota   Hybrid transaxle and then we'll compare that to  the Subaru version of it so let's let's go look at   that okay so the first thing for comparison's sake  that I want to show you is an actual Toyota Hybrid   transaxle this would be from a 2019 and above RAV4  hybrid from Toyota it has a motor generator number   two right here with 120 horsepower that when  it rotates the final drive gear rotates and the   tires rotate and the vehicle moves down the road  it has a motor generator number one that starts   the internal combustion engine and becomes a  generator when the engine is running it can   also be used to vary to create a continuously  variable transmission gear ratio between the   engine crankshaft and the final drive so in a real  quick description that's how the Toyota hybrid   system transaxle works and the Subaru system is  identical except it's in a longitudinally mounted   rear-wheel drive transmission case instead of a  front-wheel drive trans action like this one so   let's go look at the parts and see what we can see  on this train this new transaxle okay the Subaru   transmission uses the same motor generator number  two that I just showed you from the RAV4 hybrid   it's the exact same diameter same thickness  same horsepower rating same kilowatt rating   uh I believe it's the exact same rotor for  motor generator number two here's the stator   four motor generator number two and it looks just  like the one in that RAV4 over there other than   the three-phase cabling uh attaches in a different  location and that's motor generator number two   here's motor generator number one same thing same  diameters same diameter same thickness I don't   know what the power rating is on this one from  Subaru but it appears to be the exact same one   that's in that RAV4 a Toyota p710 transaxle and  then here is the mg1 motor generator number one   stator assembly so I'll get the Staters out of the  way because we won't be looking at those in any   detail in this video instead I'm going to build  this transmission starting with motor generator   number two and show you what it connects to and  how it makes the vehicle move forward in electric   vehicle mode remember this Subaru Crosstrek Hybrid  here is a plug-in hybrid it has a 8.9 pretty close   kilowatt hour lithium-ion battery in the back an  air-cooled battery it can drive on electric power   only and then the internal combustion engine  comes on so let's look at the electric power   only method of moving the vehicle down the road  and it only involves motor generator number two   as far as I can tell on this particular model so  I'm going to bring in a few other parts here the   rotor itself has some splines that connect to  a Sun Gear of a planetary gear set and this   planetary gear set is called the motor reduction  gear set and its job is to cause a gear reduction   to take place which multiplies the motor torque  so the motor torque on this rotor here is 202   newton meters or 149 pound feet of torque and  if we run it through a gear reduction planetary   gear set with the ring gear and a and a planet  carrier then we will get a 3.428 gear reduction   so let me put all the pieces together here  for those of you who are curious this motor   reduction planetary gear set has 42 teeth on The  Sun Gear 30 on the planet carriers and 102 teeth   on the ring gear or internal gears it's sometimes  called okay then we have an output gear so here's   an output gear I'm going to put it right on the  planet carrier and now we've got the stack up for   making the vehicle move down the road I'm going  to bring in a couple of wooden V blocks here   and put this thing put this assembly in it Okay  so we've got our motor generator number two if   the vehicle needs to move forward the direction of  rotation is this way and we will rotate it we have   a gear reduction unit with the ring gear bolted to  the case of the transmission so it does not rotate   and that causes a 3.428 to 1 gear reduction from  motor generator number two to this gear over here   that connects ultimately to our ring and pinion  gear set and makes the vehicle move down the road   okay so the gear that it connects to is this  gear right here and it just sits in here whoops   wrong direction sits in here like this and so as  the motor generator number two rotates this gear   rotates also and it let me slide these  out of the way for a moment connects to this pinion gear shaft so it's going to slide   right on there like that and rotate and that gives  that connects to a 10 tooth pinion gear that then   turns a 37 tooth ring gear in the final drive  assembly of this transmission a rear-wheel drive   all-wheel drive transmission this is an  all-wheel drive and that's different than   the Toyota version of this transmission uh the  transaxle because they didn't have an all-wheel   drive a mechanical all-wheel drive Toyota had  an electric all-wheel drive with three-phase   cables going to the rear electric motor but  this is a mechanical all-wheel drive which   is which sacrifices a little bit in efficiency  but it also transfers torque directly through   and that can be an advantage especially if  you're going uh off-road which this vehicle   is intended actually to do that Okay so just  a quick review motor generator number two turns a planetary gear set for gear reduction  turns a drive gear that turns a driven gear   that turns a pinion gear that turns our ring  gear and as this ring gear turns our CV half   shafts are connected to this and are tires which  means our tires spin the exact same speed as this   ring gear and differential case this is an open  differential and the vehicle moves down the road   and that's all we need for electric vehicle mode  but this is a plug-in hybrid so that's all that's   used in the electric vehicle mode operation  but once the battery state of charge gets down   low enough that we need to kick in some  additional power from the internal combustion   engine then we need to start the engine we need  to be able to keep the high voltage battery from   going dead or from losing more state of charge not  from going dead and then also to have the internal   combustion engine help turn this same gear here  to help turn the ring and pinion gear set to   make the vehicle move down the road so let me get  these out of the way and let's bring in our other   electric motor all right now we've got motor  generator number one motor generator number   one has a few jobs it has three jobs its first  job is to start the internal combustion engine   its second job is to as driven by the internal  combustion engine turn into a generator and bring   the high voltage battery state of charge up to a  certain point it's not going to charge it all the   way in most cases I can't remember on this car  if it has a full charge option or not I do not   think it does I've read about some cars that  do but it can bring it up to a certain level   and then this also works with another  planetary gear set called the power split   gear set to give us different gear ratios from  the engine crankshaft to this drive gear back   here to turn the ring and pinion gear set  on and our tires so let's bring in these   other parts and and see what they are motor  generator number one right here connects to   a Sun Gear of a planetary gear set the motor I'm  sorry the power split device gear set and then   there is an input shaft from the internal  combustion engine there's a damper and   torque limiter out there where it connects  directly to the engine crankshaft but this   is the planet carrier and it has our three  Planet gears on it by the way the Sun   Gear has 30 teeth the planet carriers or Planet  gears have 25 and the ring gear has 78 and yes I   know that blows away a lot of you thinking that  that's not the right number of gear tooth count   it is I've double checked it I know there's a  formula to decide how many teeth should be on   the ring gear based on taking the Sun Gear teeth  count and adding two times the planet carrier or   the planet gear teeth count to get the ring gear  count but that isn't always the truth and I have   one example here this one does this one does not  work with our formula so anyway we have an input   shaft from the internal combustion engine that's  going to come in and the planet or The Sun Gear   is going to go connect to the planet carrier  and then we have another ring gear right here for this planetary gear set and this  ring gear has a splined output shaft where it connects to a drive gear  right here all right now let's bring in   some v-blocks and we'll hook this uh Stack Up in  the v blocks and take take a look at how it works   all right then we also have an input gear  from the engine internal combustion engine right there okay so let's take a look look at  what we have in this gear lineup we have this   gear right here that is actually driven by  another gear that connects to the crankshaft   of the engine through the through the damper so  this gear has 35 teeth this gear has 37 it's a   1.05 to 1 gear reduction from the engine to this  input shaft so as the engine is rotating it turns   this input shaft that input shaft is connected  right to the planet carrier of our power split   planetary gear set now let's just ignore that  uh gear that I just showed you for now there   are three things that I want to show you next  so first starting the internal combustion engine   to start the internal combustion  engine all we have to do is turn   the generator here motor generator number  one we will turn it and notice as it rotates   it causes the the gear that connects to the  internal combustion engine crankshaft to rotate   and we can spin it really fast that'll spin  the engine crankshaft really fast and and   cause the engine to start now once the engine  is started notice I can spin that input gear and it will cause a the motor generator  number one to spend 3.6 times faster than   the input gear is spinning so there's a 3.6 to  1 overdrive right there as we're starting the   engine there's a 3.6 to 1 gear reduction  to start the engine so starter generator and the starter is a motor so they call it motor  generator number one all right so we've seen   starting the engine and becoming a generator to  recharge the high voltage battery up to a certain   state of charge all right now this gear over  here on the end that we haven't done anything   with this is the output gear from the engine and  the motor generator number one from the engine   crankshaft notice if I hold it solid and spin the  engine crankshaft connected gear it it doesn't   rotate if I spin motor generator number one it  doesn't rotate but if I spin them both together   it does rotate and what happens is  we can spin the engine crankshaft and   the electric motor at the pretty much the  same speed and get a direct drive a one-to-one   gear ratio through the from the input to  this output gear right here we can also if   we while spinning the engine crankshaft if  we spin the motor a little or the rotor a   little faster we get gear reduction the  output gear doesn't turn quite as fast   as the input gear if we spin mg1 slower than the  input notice we are getting a faster output over   here that's overdrive if we bring it to a complete  stop we get it even higher overdrive and if we   turn it backwards we get an even higher Overdrive  so one more time if as we spin the crankshaft of   the engine if we spin the motor the rotor of motor  generator number one faster than the crankshaft   we're in gear reduction over here if we spin  at the same speed we're in a one-to-one gear   gear ratio and if we spin it slower then we get  overdrive if we stop it we get another overdrive   if we spin it backwards depending on the speed  we get it continuously variable gear ratio so   this is called a CVT continuously variable trans  transmission but CVTs have a bad name and this is   not one of those that has a bad name this is a  it's referred to in a lot of Publications as an   electronic CVT the CVTs that have had problems and  have a bad wrap are the ones that use a push belt   um like the one in this photo you know or ones  that use a pull chain like the ones in the one   in this photo, the pull chain ones are more  reliable than the push belt ones but there's two   there's actually three different types of CVTs  that I have here in the shop the push belt the   pull chain and the electronic continuously  variable CVT all right now let's take this   variable gear ratio motor generator number one  and engine crankshaft and we're going to take this   gear and we're going to connect it to the output  gear from motor generator number two over here   so notice on motor generator number two  Let Me scoot this over a little bit here   the output gear over here has two gears this  smaller gear is what this gear from motor   generator number one is going to connect to so  if I let me scoot these Staters out of the way if I bring in our motor generator number one get it lined up there we go okay so now we've got  the entire lineup as it is inside the transmission   housing we have our motor generator number two  it's gear reduction unit and the output gear that   drives the ring and pinion gear set that's the  electric only mode that we've talked about then   we've got our continuously variable transmission  through our power split device we have a gear   that drives a smaller gear here but these two  are connected together on the same output shaft   so what I'm saying is if this gear rotates so  does this other gear and so does the ring and   pinion gear set and your tires the large gear has  41 teeth the small gear has 32 teeth and it gives   us a gear overdrive of 0.781 to one so as we're  driving down the road and our high voltage battery   state of charge gets low our engine is off so  I'll hold this gear from rotating motor generator   number two is propelling the vehicle and notice  we've got our output gear driving notice our mg1   is spinning but it's usually not generating  power at that point because it would be using   power to generate power which is a loss we would  have electrical power we'd have to spin it with   the internal combustion engine okay so then once  the state battery state of charge gets low enough   then we start the internal combustion engine so  we spin motor generator number one faster than   the engine crankshaft and get the internal  combustion engine to start once the internal   combustion engine starts then we can start playing  with the variable gear ratios so if we spin   everything the engine the internal combustion  engine input gear and motor generator number one   the same speed notice that cause whoops I'm  spinning in the wrong direction that causes the   output gear to turn and it causes our output drive  gear for the ring and pinion gear set to turn also   and that would transfer engine torque through  our our power split device gear set into the   um output gear notice that's also causing motor  generator 2 to rotate and motor generator 2 as   it's rotating can be a generator to generate more  power to recharge the high voltage battery to a   certain state of charge if the high voltage  battery has enough power then this can act   in parallel with the internal combustion engine  and the power split device and give us a parallel   mode where it um helps the engine crankshaft go  down or Propel the vehicle down the road we can   also have the a series mode where the internal  combustion engine is spinning fast and this   jet this motor generator number one becomes a  generator to provide power to motor generator   number two to move the vehicle down the road now  I did not see on the description for the Subaru   if motor generator number one ever combined with  motor generator number two to move the vehicle   down the road I don't think it does the original  Toyota Prius Prime here in the United States that   started in 2017. had a special one-way sprag  type clutch on the flywheel to keep the engine   from spinning backward if we use both Motors both  electric motors rotors to propel the vehicle down   the road the engine crankshaft would could spin  backwards but in this case from what I've read   and for the RAV4 also it doesn't do that but  I could be wrong but I couldn't find anything   talking about a one-way flywheel device this  output gear that we've talked about that drives   our ring and pinion gear set that is for the front  tires so this is front wheel drive operation only   but I told you this this is an all-wheel drive  vehicle Subarus are famous for having all-wheel   drive so now we've got to look at what additional  part is added to all of this to give us all-wheel   drive so here on the motor generator number two  and the and the gear reduction and output gear   to drive the front ring and pinion gear set this  gear if we look inside of it let me pull it off down inside of this gear it has splines  for another shaft to come in and connect   to so this is the rear output shaft inside  the transmission that goes to a special   electromagnetic activated clutch pack that then  can send torque or apply torque to the rear axle   so this vehicle is normally front-wheel drive  but we can apply a torque to the rear axle   as needed to give us all-wheel drive so let's  take a look at that all-wheel drive clutch pack   okay the all-wheel drive clutch pack sits  in this clutch drum right here that has two   wires coming off of it and if we look  at the back right here it's got this electromagnetic clutch it's just a big coil  of wire like an air conditioning clutch   compressor clutch air conditioning compressor  clutch I have put Power and ground to this   real quickly and this became a magnet a very  strong magnet on the scan tool as you can see   in this photo here the scan tool that the  Subaru scan tool will let you apply up to 3   000 milliamps of current to this clutch coil and  test it and so the resistance of this clutch coil   when I measured it yesterday was around three and  a half ohms uh so if we connect that to 12 volts   we'll get somewhere in the 3 000 to 4 000 milliamp  or three to four amp uh range of current now this   clutch drum that that spins freely here has this  input shaft that I showed you or the output shaft   that I showed you going through it and since  this is an electromagnet what the electromagnet   is going to do is it's going to attract this steel  plate right here and pull this plate down against   that magnetic surface down inside there  as it pulls it down it will apply Force   to a two fiber disc clutch pack that's in  there so we have down in the bottom of this clutch housing two plates that connect that have  splines that connect to the outer housing   two plates that have internal teeth  that connect to an inner housing and then we have this big steel plate right  here that sits on top of all of that and as   the magnetic field is present it pulls down  really hard on that and it stops those clutch   plates that could slip it prevents them from  or tries to prevent them from slipping now as   it tries to prevent them from slipping there's an  interesting little piece in the middle of all of   that right here this little Hub with these balls  on it this is called a ball ramp and if these   balls are forced to move one way or the other they  roll up a ramp and try to separate pieces and so   this metal plate sits on top of this ball  ramp assembly and it has little ramps down   in it also and so it's going to set right there  just like that and then notice as I rotate it   it separates so not separated, separated, back and  forth as it as the bottom piece tries to spin   it pushes up on the top piece pushes up so what  causes the bottom piece to start spinning is the   electromagnetic clutch that we just looked at  so electromagnetic clutch comes on it grabs this   splined piece underneath starts at rotating as it  rotates it pushes up on this clutch apply plate   and this clutch apply plate has a seven clutch  fiber disc clutch pack that as it pushes up it   will try to compress but we can't compress so  it squeezes and puts force on those clutches   and stops them from rotating and that causes  this shaft that's already connected to the   the drive gear on our mg2 output here to  transfer torque through the housing itself to a big plate that sits on top here and the output shaft that goes to the  rear drive shaft and the rear axle   to make the vehicle move down the road so  during non-all-wheel Drive operation this   shaft can spin these clutch plates can spin  without being held solid to the output shaft that   from the drive gear that provides the torque that  goes to the rear axle so in other words these two these two shafts are not connected together  when the electromagnetic clutch comes on the   ball ramp is activated it pushes up on these  fiber clutches squishes the big clutches clutch   plates together and connects this output shaft  to the input shaft and gives you torque to the   rear axle now these are all spinning pretty much  the same speed anyway we just need to apply the   clutch discs to transfer the torque all right  I'm going to hurry and put this back together   and then I'll show you where it goes in the  in the whole lineup with the transmission okay I've got the clutch pack reassembled we've  got our input shaft right here from our drive   gear and we've got our output shaft right back  here that goes to the rear drive shaft so that's all together like that now if we bring in our mg2 right here this input shaft right here is going  to go right up the middle of motor generator 2.   through our planetary gear reduction gear  set the motor speed reduction gear set   I've got a few shims in there that will be used  in the case and then that connects right to the   drive gear the same drive gear that turns the ring  and pinion gear set for the front so we're driving   the output shaft through the clutch pack to the  final output shaft here that drives the rear drive   shaft and the rear axle so as we put this whole  thing together now for one final look here we go that's quite a big long Stack  Up and as you'll see here   and as you'll see here in a minute we're going  to put this inside of the transmission case   we've my shop assistant and I have spent  a lot of time preparing this case we've   cut away sections of it so you can see  all of this as we put this back together   oh sorry there's one more thing I want to show  you uh and that is the oil pump assembly   here it has two gears on it some of you may  have been wondering why are there two gears   on the outside of the planet carrier and the ring  gear and that's because we have two oil pump Drive   gears here one of the pump Drive gears is used for  electric motor only driving the other one is used   when the internal combustion engine is driving and  they actually have a little sprag on there so that   when the one is being used the other one can just  free Spin instead of uh having to having to turn at variable speeds as that power split device  the speeds between the ring gear and the planet   carrier vary all the time because of it  being a continuously variable gear set   so there's our oil pump it just drives a trochoid  oil pump just like in all the other Toyota hybrid   system Transmissions all right let's put all this  in the Cutaway transmission and then we'll come   back and take a look at that okay it took a little  while but we put together the Subaru th2a plug-in   hybrid transaxle or transmission it's a rear wheel  drive transmission we have a front differential   right here where the front CV shafts half shafts  come out and go to your front tires and then we   have a rear drive shaft that comes in right here  that goes to the rear axle for the all-wheel drive   system it's a pretty long transmission we've got  motor generator number one up in the front here   we have a bunch of gears in the middle motor  generator number two right here and then our   all-wheel drive all-wheel drive electromagnetic  coupling in the rear we have three phase cables   right here that come in to feed motor generator  number two and then we would have cables like   that on the other side to feed motor generator  one but me and my shop student assistant Nash   made a cutaway of this transmission for you to  see did a really good job and I want to show you   this transmission okay so these are all the exact  same parts that I had here in the wooden V blocks   earlier in the video but here is our input shaft  from the engine crankshaft we've got a damper that   connects right there and you'll notice that when  it rotates it turns the input shaft and that turns   the planet carrier in our power split device which  turns The Sun Gear which is connected to our motor   generator number one so that becomes a generator  once the engine starts to start the engine we   just turn motor generator number one and notice  it makes the engine crankshaft turn right here   okay then on the rear over here we've got motor  generator number two and oh right here you can   actually see the ring gear with the teeth facing  away from you and the front differential the open   differential that our half shafts come out this  would go to the left front tire so when we rotate   in the forward direction to make the vehicle  move forward motor generator number two notice   the ring gear spins forward the ring gear in  your tires turn the same speed and direction   Okay so here's our motor generator number two our  gear reduction gear set that we already talked   about here's our parking gear so when we put it  in park it stops all of the output drive gear   from rotating prevents the vehicle from rotating  and then we've got our variable gear ratios that   come in here that drive this gear that connects  to our output gears to the to the front it also   connects to this output gear and a big long  shaft that comes and goes to our rear or our   all-wheel drive electronic torque electronic  control coupling right here and remember this   is an electromagnetic coupling so when it is  activated torque is transferred out the rear the rear of the transmission so that pretty  much wraps up the Toyota hybrid system   integrated into the Subaru Crosstrek plug-in  hybrid which I'm actually pretty impressed   with the vehicle it does have a fairly short  electric driving range of 17 miles but if that   matches your commute or a round-trip commute then  that's that's fine plug-in hybrids can be a   good transitional vehicle for people that aren't  quite ready for an electric vehicle you can plug   in hybrids are a good option and there are a lot  of there are a lot of plug-in hybrids available   out there in different configurations  so that's it thank you for watching

Channel: WeberAuto

Views: 125,586

Keywords: WSU, Weber State Automotive, Weber State University, John D. Kelly, Guy in Wheelchair, Professor Kelly, EV Boot Camp, Utah, Layton, WSU Davis, Weber State University Davis Campus, Subaru Crosstrek Hybrid, PHEV, TH2A Transmission, Power-Split, Toyota Hybrid System, RAV4

Id: QRMajgb8KiM

Length: 41min 16sec (2476 seconds)

Published: Sat Oct 22 2022