Hybrid and EV Cooling Systems

Hello, I'm professor John Kelly and this is the  WeberAuto YouTube channel. In this episode we   are going to look at the cooling systems in a  hybrid electric vehicle the hybrid vehicle I   have behind me here is a 2017 Toyota Prius eco  and this is the Prius that I've taken the P610   transaxle out of and took it all apart explored  it figured out how it worked and made a video on   that it's lithium-ion battery assembly it's  inverter converter and now I've reinstalled   the transmission back in the vehicle and I'm  about to put the radiator in along with all   the heater hoses and coolant hoses and water  pumps and everything else and I decided well I   probably ought to take advantage of this time  and show everybody the parts of the hybrid   cooling system particularly on the Toyota systems  but other systems are very similar so there are   many parts to a hybrid cooling system we have  to cool the hybrid transaxle we have to cool   the inverter assembly of course we have to cool  the internal combustion engine we have electric   water pump for the engine electric water pump for  the inverter assembly we have a heat exchanger in   the exhaust system we have a heat exchanger  for the transmission fluid we have of course   the heater core the regular part of the radiator  for the engine the part of the radiator to cool   the inverter cooling fans and all kinds of hoses  going everywhere so let's take a look at   these pieces one at a time and along with a  few other miscellaneous things that I think   you'll find interesting as we explore the cooling  system on this car so the first thing let's look   at is the electric water pump for the internal  combustion engine ok here we are under the right   front corner of the car just over my shoulder  here is the front bumper we've got the right   front brake rotor right here and as you can see  right here is the engine harmonic balancer now   normally on in any other engine there would be a  drive belt that connected to that but as we zoom   in here I want you to see that not only is there  no belt but there are no grooves for a belt that   is not a pulley that is just simply the harmonic  balancer to counteract the twisting forces of the   internal combustion engine on the crankshaft  but right next to it up in up deep there with   those weird little aluminum pieces sticking up  is the electric water pump let's get a better   view okay if we look in through the opening by  the air conditioning condenser we can see the   electric water pump we can see the cooling fins  on the left of the electric engine water pump   there and you'll notice that the coolant inlet  hose and thermostat is located on the backside   of the electric water pump so the inlet from the  radiator comes in on that tube right there we have   a 180-degree Fahrenheit thermostat that'll open up  and allow coolant to come into the electric water   pump where it's circulated through the block  first and then up into the cylinder heads okay   so we just saw the electric water pump for the  engine the inlet from the radiator with the 180   degree thermostat now the next thing is we have  coolant running through the throttle body to keep   it from icing up that coolant comes from the EGR  cooler heat exchanger so when we use the exhaust   gas recirculation system which runs really hot  exhaust gasses back into the combustion chamber   under certain conditions, we cool those exhaust  gases to make the EGR system more efficient   there's an EGR cooler that's liquid-cooled where  it receives coolant and sends it back to the inlet   of the engine block there's a little bypass  of the thermostat to keep coolant circulating   there but some of that also goes to the throttle  body to keep the throttle body from icing up with   the pressure differential there so there are  some little coolant hoses there all right so   under the hood here is our EGR valve and it has  a tube that's going to send exhaust gasses back   to the intake manifold to circulate them back  into the engine under certain conditions but   that exhaust gas needs to be cooled down to make  it more efficient and so back behind it and it's   really hard to see is a heat exchanger for the  EGR system you can see some little coolant hoses   so the coolant goes through the EGR cooler comes  down goes through a pipe over to the throttle body   itself to heat it to keep it from freezing then  the fluid returns goes back makes a turn and goes   back over to the water pump and the coolant Inlet  where there's a bypass pipe to let the fluid in   while we are here underneath the hood we've got  another hose that comes from the bottom of the   EGR cooler it goes over T's in with the hose from  the radiator and goes to our coolant surge tank or   storage tank for the internal combustion engine  this surge tank as you can see has a has a cap   that you should not open when it's hot it also has  an air release valve this little screw right here   needs to be removed when you add fluid to it for  the first time so I've drained all of the coolant   out of the engine and the inverter system and  we will have to add fluid back in but there's a   special bleeding procedure to make sure we get all  the air out while we are here under the hood we've   got the inverter with converter assembly where we  have two coolant fittings we have the inlet right   here where it comes in and goes to the dc-to-dc  converter as we saw in my inverter teardown video   and then it goes over and travels up to the up  upper part of the inverter where the igbts are   cooled and then it comes out this fitting here and  goes to this little storage tank for the inverter   cooling system so there are two separate cooling  systems two separate portions of the radiator on   this vehicle one of them to cool the inverter  and the transmission the other one to cool the   internal combustion engine the transmission cooler  is right down here as you can see we have hot   fluid coming from the transmission oil pump goes  into this heat exchanger the transmission cooler   as its called and then gets pumped back up to  the top of the transaxle where it goes in and for   lubrication and for cooling the stators and then  we have an inlet and an outlet pipe down at the   bottom there for coolant from the inverter portion  of the radiator this Weins cable right here runs   over to our electric air-conditioning compressor  right down here the air conditioning system on   this car operates very much like any other air  conditioning system except it has an electric   variable speed air conditioning compressor to  modulate the amount of refrigerant going into   the evaporator to remove heat from the passenger  compartment on the front of the vehicle we have   a standard air conditioning system received the  dryer and condenser assembly the receiver dryer   is this tube off to the side and of course the  condenser right there also while we are here under   the hood we can barely see the coolant outlet pipe  right there from the internal combustion engine   going to the radiator so that's the outlet pipe  right there and the inlet pipe is right there on   the back of the electric water pump okay so we've  seen some coolant hoses for the EGR cooling system   we've seen coolant hoses that keep the throttle  body from icing up we've seen coolant hoses for   air bleed we've seen coolant hoses for circulation  back to the surge tank or the reservoir tank on   the reservoir tank we saw the bleed screw for  bleeding air out of the system as we add fluid   if it was drained which this is drained we saw the  inlet and outlet pipes for the radiator hoses for   the engine we saw the inlet and outlet tubes  for the inverter with converter assembly and   the inlet and outlet tubes for the transaxle  cooler now we still have more before we lift   up the vehicle and look at some more components  underneath there's a few interesting parts on   the front of the vehicle that I want to show you  so let's look at those okay you're all familiar   with a horn or the horns on a vehicle this Prius  has two horns right here but right over here is   a unique little device and this is actually a  speaker and the technical name for it is the   vehicle approaching speaker and this speaker will  emit a noise and it sounds very much like brake   rotors rusty brake rotors rubbing on brake pads  at a slow speed this will emit a noise if you   are in Reverse or drive from a speed of pretty  much zero through about 15 miles an hour five   kilometers per hour it's to alert people that a  vehicle is approaching because in hybrid electric   mold in just electric vehicle mode these cars are  so quiet that some people don't hear them coming   and so it emits a sound the sound makes as soon  as you put your transmission in drive or reverse   this sound gets extra loud for one second and then  it quiets down and then it gets louder and louder   with the faster you go up to the 15 miles an hour  at 25 kilometers per hour so an interesting little   speaker just has two wires to elect any speaker  and I'm going to measure its resistance and see   if what the voice coil resistance is if it's just  a standard speaker and see if I can hook something   else up to it and play something play something  different maybe an interesting little device   there's a there is a Federal Motor Vehicle Safety  standard that's proposed I am NOT positive that   it has been made into a final rule or a law that  says that these vehicles must emit a sound as they   drive automatically to keep from surprising or  startling people that don't hear them coming all   right another well of course that's not related  to the cooling system but this is related to the   cooling system so this assembly right here is  called the radiator shudder assembly and as you   can see it has two radiators Shutter fins right  here and these fins are open they can be closed   they can be part way open there's a actuator  over here on this side that has a position sensor   inside of it and then there's a temperature sensor  over here to measure the outside air temperature   also the purpose of this shutter assembly is to  increase efficiency as you drive so to decrease   wind resistance so when we don't need air flowing  through the radiator because the engine is off or   it's cool enough or whatever reason we can close  these fins and decrease our coefficient of drag   now as I mentioned over here on the passenger side  is the actuator assembly now this is only a four   wire electrical connector here but there are six  wires right here and I thought well what's that   all about by the way the four wires are  power ground and the two canned communication   lines to communicate with the actuator module so  if you guys have watched any of my videos before   you know I like to disassemble things that aren't  supposed to be disassembled so I just gotta have   my pocket screwdriver and popped off the cap  to this actuator here we go and turns out the   actuator itself just comes undone it has a little  gear drive right there that plugs into the bottom   fin so with that actuator gone now I can close  and open these fins myself but right here is a   three wire potentiometer it looks like and that  explains the additional wires that are in the   electrical connector for the actuator that are  not in the main harness that plugs in from the   hybrid control module that's in control of the  position of these and of course there are 13   trouble codes for this actuator I would imagine  that it is well it looks like a brushed DC motor   oh by the way the water pump the electric  water pump for the internal combustion engine   is a brushless DC motor at a low voltage 12  volt brushless DC motor okay so anyway that   is the shutter assembly and it has its it has its  own trouble codes as I said there are 13 of them   there are 26 pieces of data on the data list  for this actuator and temperature sensor and and   so on and you can use your scan tool to command  these to open and close and test them to see if   it's working like it should so that's the shutter  assembly and that will affect the cooling system   okay the next thing we are going to look at is the  exhaust heat recirculation system and we'll have   to lift up the vehicle to look at this system  which is not new to the 2016 or fourth generation   Prius I believe it was new to the 2010 Prius which  was the third generation but it takes exhaust heat   and runs it through a heat exchanger where it can  under certain circumstances heat up the coolant   that is fed to the engine block to help the engine  warm up more quickly to reduce exhaust emissions   so let's take a look at that okay we are under  the car and looking straight up at the back of   the engine block and we have the exhaust manifold  covered in a heat shield and as a close coupled   catalytic converter there a three-way three-way  catalytic converter to reduce hydrocarbons   carbon monoxide and oxides of nitrogen and it's  close coupled so it will start working almost   immediately and then if we come downstream of that  catalytic converter we have a second three-way   catalytic converter followed by the exhaust heat  recirculation system right there in the middle   followed by a sub muffler and then of course clear  to the back of the vehicle we have a muffler okay   here we are under the car and let's take a look  at the exhaust heat recirculation system so the   first thing I want you to notice is there are  two coolant hoses coming down here this is the   inlet to the heat exchanger up on top of this  exhaust heat recirculation system and of course   this is the outlet the coolant that comes to the  exhaust heat recirculation system has actually   gone through the heater core already it does help  preheat the coolant that goes through the heater   core but the hot coolant that goes through this  exhaust heat recirculation system goes into the   engine block first then up to the cylinder heads  and then into the heater core and then back out   here to the exhaust air circulation system making  a complete loop so let's see how this thing works   so we have coolant coming in from the heater core  coolant going out to the engine block the coolant   coming in goes up to the top to a heat exchanger  so you can see your a tap on top there I've got   it labeled heat exchanger and that heat exchanger  runs the length of the exhaust heat recirculation   system so we can't see how long it it is but  it's big then we have an exhaust heat control   actuator right here that is going to push on this  control valve now right now with everything cold   the control valve is closed the control actuator  is off and not extended and what that means is   exhaust will come into the recirculation system  and then go up through the heat exchanger where   the coolant goes through come over and down into  the back part the exhaust heat recirculation   system and then into the sub muffler so it does  not have a straight path through the exhaust heat   recirculation system it has to go up it takes  a 90-degree turn takes another 90-degree turn   goes to the back another 90-degree turn comes down  another 90-degree turn and goes out the back now   as the coolant heats up this actuator will extend  and it will push on this valve right here and this   valve is spring-loaded as you can see I've brought  it up when that actuator sticks out and pushes on   this valve you can see I'm pushing on the valve  myself when that valve gets pushed up all the   way it shuts off the exhaust flow through the  heat exchanger up on top and just simply allows   exhaust to come straight through the exhaust heat  recirculation system as if it was just a straight   pipe so the exhaust heat recirculation system  preheats the coolant that goes to the engine   when and is needed which would be pretty much  any time the engine coolant is is not warmed up   enough so rather than wasting the heat produced  by combustion and just sent it and not sending   it out the exhaust pipe we are recovering some  of it and helping heat up the engine now there's   one other thing related to the exhaust system  I thought I'd show you while we're here this   muffler has a special spring-loaded valve inside  of it so the exhaust that comes in normally would   have to take a roundabout path to come out the  exhaust pipe the tailpipe here but under heavy   acceleration under high pressures there's a valve  over here that will open up and allow the exhaust   to take it more straight path sort of the muffler  and what that does is it allows the vehicle at a   idle especially and low load conditions to be more  quiet and to reduce some of the the vibrations   caused by combustion pulses in the exhaust system  okay we are finally to our last component of the   cooling system and that is the radiator system and  the fans and everything that goes with that but   before we look at that and put all that together  to reinstall it in the vehicle let's just take a   look at a few other things under the vehicle  from a different perspective so straight up   here is our electric air-conditioning compressor  and then right here is our automatic transmission   fluid cooler and then of course the transaxle  that I had out on the bench and did all those   demonstrations and videos with is right here so  let's take a look at the radiator system now okay   I have the radiator here out of this 2017 Toyota  Prius eco and this radiator although it looks like   just about any other radiator at first glance  it's actually two radiators in one from about   right here across you can see a dent right there  and kind of a dent right here that section of the   radiator is just for cooling the inverter with  converter and the automatic transmission fluid   and then everything above that is for the internal  combustion engine and EGR cooling so let's take   a look at what fittings and parts are here first  since there are two radiators there are actually   two drain plugs so we've got a drain plug right  here for the inverter portion of the radiator and   a separate drain plug right here for the engine  portion they have some little tubes sticking out   of the side of them when you drain this coolant  you're supposed to put a hose on it and bring it   down to a drain pan or bucket so that it doesn't  just run all over the frame and get all over the   place but they don't put the hoses on them anymore  out of the factory like they used to on this lower   radiator portion there is an outlet tube right  here that goes to the inverter assembly and then   there's a fitting right here from the automatic  transaxle fluid cooler so just a an in and an out   on the lower portion of the radiator and then on  the upper portion here for the internal combustion   engine this is the inlet from the cylinder head  so this would be the hot fluid coming in and then   we have the outlet over here that would go to  the inlet with the thermostat that we looked at   connected to that electric water pump and then up  to the top here we have this little tiny tube one   on each side this is an outlet to the coolant tank  so it's it's an air bleed basically is what   it is it allows air to escape the system allows  us to bleed the system and there's a long tube   that goes over and up to that coolant reservoir  that we saw underneath the hood and then this   other tube over here receives coolant from the  coolant reservoir so it's an inlet so we have a   inlet from the engine an inlet from the coolant  reservoir and then an outlet to the engine and   then an outlet to the coolant tank so what is that  one two three four five six six hose fittings to   drain plugs two sections of the radiator now of  course there are two cooling fans that go with   this let me get the fan shroud and fan assembly  here these fans spin in opposite directions of   each other looks like this one this one spins this  direction and this one spins this direction this   fan shroud is quite easy to remove and install  it just has some little clips that slide into   some brackets on the radiator itself of course  we've got to be careful and make sure that we're   not bending any cooling fins on the aluminum  radiator itself and then we'll just pull down there we go and then it's got some clips that  lock it into place so now our fan shroud is   connected to the radiator itself alright now we  have as part of this fan shroud as you can see   here there are two bolts those two bolts are for  an electric water pump to circulate fluid through   the inverter and the transaxle cooler and back  through the lower portion of this radiator this   she also uses a brushless DC motor which by the  way there are trouble codes for both the internal   combustion engine brushless DC motor water pump  and the electric water pump here Brussells DC for   the inverter assembly this would be the inlet  to the pump and this would be the outlet this   outlet goes to the top fitting of the coolant  heat exchanger for the transaxle I forgot to   look up the torque on these bolts I'll have to  just snug them up for now and then look them   up I'm sure it's not very much since they screw  into captured nuts in a plastic fan shroud all   right so that's our water pump for the inverter  portion the lower portion of the radiator here   all right the next thing I want to look at is the  coolant reservoir for the inverter portion of the   radiator so we've got our own coolant reservoir  it just snaps into place like that and then   it's got a hose that comes over and connects to  the electric water pump like that I'm not going   to put any clamps on here because I'm going to  take all this off too and put it back up in the   vehicle I just want to show you the amazing  plumbing involved here all right we also have a   long coolant pipe that goes over to our surge  tank and we've got the hose that comes from   the coolant tank back to the radiator right there  looks like I've got a broken bracket right there all right over here on the inverter  tank side we've got a hose that   goes from the lower portion of  the inverter through a bracket and the clip and that these two hoses go to the  inverter so this is the inlet to the inverter   this is the outlet from the inverter those two  hoses right there then we have our long radiator   hose from the cylinder head this is going to come  in right here like that and on the other side we   have our outlet hose to the inlet of the engine  and then finally we have one last hose that goes   from the inverter coolant portion of the radiator  over to the transmission cooler so let's lift this   up and take a look at what we have here this is  a little more than what you find on most vehicles   anymore okay let's review all the plumbing here  on this 2017 Prius eco radiator system we've got   a water pump right here an electric water pump  for the lower section of the radiator which is   for the inverter cooling so we have the inverter  coolant storage tank the water pump pulls fluid   down pumps it out this hose right here to  the transmission cooler then the fluid from   the transmission cooler goes back over and into  the radiator on the lower section with Anik goes   through gets cooled comes back up and goes into  the bottom of the inverter assembly where it cools   the dc-to-dc converter then goes into the top of  the inverter assembly and cools the IGBT modules   and then comes back into the coolant tank making  one full cycle then on the engine side of things   have the radiator hose here from the outlet from  the cylinder head on the engine that comes down   there's temperature sensor right here that comes  into the radiator goes through the radiator comes   back out on this other hose here where it goes in  through the thermostat if it's open and circulates   through the engine block through the heater core  through the exhaust heat recovery system and also   through the EGR cooling system there's three paths  that this coolant through the two big hoses   goes through so the three are the engine block and  cylinder head and then in parallel with that we   have the EGR cooler system and the throttle body  de-icing system and then in parallel with that we   have the heater core and the exhaust heat recovery  system and then we have an air bleed hose at the   top that goes over to the coolant tank and then I  inlet from the coolant tank also and that's that's   the radiator system here on the on the Prius now  if we look back at previous Priuses they would   all be very similar to this the same thing other  than some of them did not have EGR valves with a   knee-jerk cooling system the first two generations  of Priuses didn't have the exhaust heat recovery   system but they all had inverter cooling systems  with at least one electric water pump they all   have a special bleed and fill procedure so as you  fill up these two separate cooling systems the   inverter system that we have to fill up we just  put coolant in we use a scan tool to command the   water pump to run and we keep running it until the  level in the reservoir up here stabilizes on the   engine side of things we after put the engine  the hybrid system into what's called maintenance   mode to force the engine to run and then warm it  up open that bleed screw on the coolant tank and   keep adding fluid coolant until it stabilizes and  that is the fluid level stabilize us now the only   coolant that's approved for use in Toyota hybrids  is the super long life coolant from Toyota or the   equivalent they have very specific specifications  for their coolant like any other vehicle   manufacturer does it's the same coolant that's  used in both the internal combustion engine and   the inverter assembly which is pretty typical of  any other hybrid vehicle or electric vehicle I've   got our Chevrolet bolt right there that has three  different cooling systems in it batteries coolant   system the electric motor cooling system and the  inverter cooling system and they all use the same   coolant I've got a Chevrolet Volt right there  with three cooling systems the engine cooling   system the battery cooling system and the inverter  cooling system they all use the same coolant but   it's not this cool and it's whatever the vehicle  manufacturer calls for this Toyota super long   life coolant is already pre-mixed it's already a  50-50 mix so do not mix water with it all right   we've seen a number of things that are part  of the cooling systems on this Toyota Prius   and I hope you've enjoyed it I hope you've  learned a few things thank you for watching

Channel: WeberAuto

Views: 138,106

Keywords: ASE, Toyota Prius, Hybrid Engine Cooling, Ford Fusion Hybrid, Ford Fusion Energi, Weber State Automotive, Exhaust Heat Recirculation System, John D. Kelly, Weber State University, NACAT, STEM, Hybrid Exhaust System, Chevrolet Volt, Hybrid Cooling, WSU, Inverter Cooling, Tesla, Professor, CAT, Super Long Life Coolant, Chevrolet Bolt, CCAR, Transaxle Cooling, NATEF, Aisin, Guy in wheelchair, Service Precautions, Hybrid Air Conditioning

Id: LTxGlUDcTDs

Length: 36min 43sec (2203 seconds)

Published: Sun Nov 26 2017