How Hybrid Car Brakes Work
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- čas přidán 22. 07. 2024
- Here’s an in-depth look into the braking system of the Toyota Prius Hybrid.
Hybrid cars cannot use traditional vacuum assisted brake boosters. This is because when the internal combustion engine is shut off, there is no vacuum available to power the brakes. In addition, hybrids use regenerative braking by turning the electric motor in the transmission into a generator to charge the battery. Thus the computer must control the braking pressure applied to the calipers to balance it with the force from regen braking for optimal efficiency and seamless operation to the driver.
A hybrid car’s brakes implores the use of a traditional brake fluid reservoir and master cylinder. The master cylinder takes fluid flow, generated from the brake pedal from the driver and sends it to the stroke simulator. The simulator is cylinder that fills with brake pressure and provides the driver feedback of where the brake pedal is and how much force to apply - although it is still not mechanically linked to the force being applied to the wheels.
The ABS actuator has an electric motor that drives a hydraulic pump that fills an accumulator. This provides the brake pressure to the apply and release solenoids that lead to each brake caliper. The computer can use this setup to completely electronically control the braking system based on the pressure sensed from the driver’s input and the caliper’s output as a closed loop control system. It also interfaces with the hybrid regenerative system through the CANBUS so the braking forces are related to what the driver has requested. The fluid from the master cylinder is cut off completely during this operation, and are left in the fail open position for manual operation of the front brakes in the event of no power.
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Thanks for braking that down for us!
You are welcome
How did you know that I was looking exactly for this? When I pressed that pedal, I knew funny stuff happened under my feet and now you confirmed it.
Glad the video came at the right time!
Hi, I have recently brought my first full hybrid (FHEV). Being a electromechanical design engineer, I am fascinated how EV work. Watched several of your videos on hybrid systems and this one on regenerative braking explains in detail the electromechanical complexity. Love the diagrams and explanation.
Glad you appreciate the detailed teardown. I love seeing how things work
Thank you very much for this, this is extremely informative. You are a master in the art of explaining things quickly and eloquently. P.S. I freakin love the toothbrush pointer and the ever-excited grinder that’s always ready to do your dirty work. 👍👍👍
Excellent video. Thanks for taking the time to direct this for us.
Brilliant and detailed knowledge, thank you!
Literally waiting for this,thanks a lot !!!
You are welcome. Just for you
And where does the “internal leak” occur? This is probably the most important question. "PRV"? or through other valves? How to fix a leak? What was the point of disassembling it, sawing the solenoids for some reason, if it is already clear that there are coils of copper and nothing else. And you can’t get to the place where the main breakdown of this module occurs... But in fairness, this is the only video on CZcams that I was able to find with such a deep analysis.
Truly awesome Video!! Well done!
Thanks for the detailed video. Very informative. By the love your universal hex removal tool 😂
Excellent explanation of hybrid braking system..Thank You..
You are welcome
Awesome!
How do you all the detail 😮
Good job sir
Thank you
Good video. The holes on the sides of the ABS block are sequencing valves.
I love when you open up the parts and explain what they are/do, it really helps me understand, thank you so much, as always great video!
You are welcome! More to come
Respect! Such a good explanations
Great video. I really like what you do! Hilarious that some people call classic Citroën´s brakes "over complicated". THIS is what I call complicated.
I wouldn't call this complicated... It's just handing over all braking duty to a computer and solenoids with a simple hydraulic circuit.
@@speedkar99 It´s just me, thinking this could have been built much simpler based on the system from old Citroën´s and their high pressure brake system. And I have heard a lot of people saying stupid things about Citroën´s. :) But I guess this is how they have to do when they want it to feel like "normal" brakes. At least they didn´t fall for the temptation to use vacuum pumps and stuff. BTW, Citroën´s have a rather simple valve connected to the pedal. So the only thing you do with your foot is letting already created pump pressure access the calipers.
I love old school Citroen brakes! Rock hard pedal, travel is 0.01mm or something like that. Just a pressure sensor, with built in sensitivity to the car load.
So I’d like to have the artificial feel removed from our Prius brakes :-) Probably impossible, as it measures pedal travel for the regen braking, I presume.
Yes, we have both a Prius and a Citroen Xm, excellent cars in their own league!
Thanks for explaining this!
Great video, thank you.
You are welcome
Great video. However, the part numbers would make it the best. That way we could learn to fix it. thank you
Ok, thanks
I understood little but got entertained a lot. That matters more.
Unique master. Thank you for the video. just super. Thank you so much .
I have a question . Prius 2021 if I pump the brake pedal 10 times or more , then the pedal travel decreases and becomes stiff, hard to push , if i start moving and try easy stop the car stop down sharply instantly. If I turn car off, after 3 minutes there is a slight bump under the steering wheel and the brakes start work normally again. Is it bad ABS? The car was damaged by water.. No DTS . Thanks
ofc lets make this absolutely critical system as complicated as possible, what a great idea
It works! But they do fail .... And it's $$$ more than a regular msster cylinder to replace!
Well explained, nice video.
Thanks
Great video. it interesting to see valves inside actuator block and condition of valves.
It sure is cool
No pigs harmed on this video. This braking system just works
Until it fails...and they do fail.
Thank you very much for another great video, this is a real reverse engineering.
I loved ur universal hex removal tool 🤣
thanks for video uploaded.i was sad for your video.love you from Pakistan
Hi from Canada
After finding this so complicated, I feel like driving the car without brakes 🥴
The old foot through the floor board Flintstone brakes eh
@@speedkar99 😂😂😂
I modified my hybrid brake system by installing traditional brake booster and motor for vacuum creation now i drive car safely
Very nice sound thanks
Can c1391 be fixed only by replacing the fluid brakes water? Without the replacing abs module
I like to see you putting it all back together.
@@EpicDrew15 is a joke
With an angle grinder
@@speedkar99 and superglue
thanks you so much.. i will subscribed and click notification. . good work.
I had a Prius that needed to be started with the E-brake in cuz it would roll and the brake pedal did nothing but pulse and no stop. ABS light was in occasionally, but pretty random. Now I have a better guess why... thanks SK99!
You are welcome. That's interesting...it wouldn't engage the brake and just pulse. I guess the actuator was bad
It’s hard to believe something this complex works reliably for 100’s of thousands of miles
Great video
Thanks
Massive amount of engineering goes into these cars .
And massive amount of money to repair.
Agreed. And massive amounts of tooling and material to mass produce
At 03:21
The coil is likely an electrically controlled valve.
Energizing the coil creates a magnetic field that moves a piece of metal inside the aluminum tube the coil is placed over.
Just like the solenoids you show at 09:56
All that space shuttle technology for that braking system when a little electric vacuum pump would mean that you could just use regular barke stuff.
Electric Vacuum pump ?
That wouldn't be efficient
Q#1: When I am coasting down a hill and I take foot off of all foot pedal with shifter in D, am I regenerating with mg1 or mg2 or both?
Q#2: in the situation above, if I also apply the foot brake pedal lightly, will I be activating another generator or applying brake pads to rotors?
Q#3 if applying brake pedal lightly does in fact initiate additional regeration, does the pressure of my brake pedal correspond to the aggressiveness of regeneration?
Hi, I have a new rav4 hybrid. Lately notice break paddle is kind of stiff or hard to press down before starting the car. Before was smooth and soft. In your opinion, what could be the problem? Thanks.
I really appreciate the breakdown of a Prius' braking system, but with the actuators failing, what's the main culprit that causes it? I was hoping that you'd mention where the main issues are with the actuators.
Solenoids can burn out.
Pressure sensors can go bad or miscalibrate, and the brushed motor can wear out.
@@speedkar99 Actually all these reasons are very seldom, maybe 1%. Most common reason is valve leakages inside of that sealed metal block.
Great vid! So you are saying that if the ABS accumulator quits working, then the master cylinder will send fluid directly to the front brakes only, correct? Is the car safe to drive if that happens?
Hello, I need from some advise.
I have a Lexus RX450h 2010y. When I pressed the brake pedal hard and I hearing some noise, in the other time (when I press it slightly it is less rare). I changed the brake water but still have it that nois. Techstream dont show me any error codes. Where can be the problem?
the new integrated braking system from Continental, called MK C1 simplified the hybrid braking sistem by integrating the master cylinder, brake booster and abs module into one single unit that handles boosting, abs, esp, pedal feel, and regen braking.
Toyota had some issues with that nitrogen accumulator on early priuses but now it seems it's all good
That problem is called demolecular diffusion and happens to all accumuators. It´s just like a tire evetually will loose all it´s air if you don´t fill it. Accumulators is a service item. There are things you can do like "arm" the rubber diaphragm in different ways, like Citroën did in the 90´s. But usually this just mean that they stay with the right pressure for longer and instead break completely when that day comes. So "all good", I wouldn´t count on that. Another "interresting" is that normal or catastrophic leakage of accumulator nitrogen pressure ends up as bubbles in the fluid. I guess it can be confusing when you suddenly get "air" in your brakes that seem to come from nowhere.
Where is the nitrogen stored and what is its function? I thought the accumulator was a storage tank for brake fluid
Toyota is integrating the brake actuator now on many of it's RWD Lexus and truck models
@@speedkar99 Accumulators usually have a diaphragm, so it´s basically a glorified "balloon" filled with (usually) nitrogen inside it. It´s all about the idea that you can compress a gas but not a fluid. It´s how you store accumulated hydraulic pressure.
Another informative technical tutorial, thank you sir! I actually modified my driving habits After viewing your excellent lesson on the CVT transmissions.
So, what’s the maintenance recommendation for the regen brakes? Fluid change? I got the new ford maverick hybrid a couple months ago. Love it. Now I know how the brakes work.you need to open a technical academy. Thanks a lot, keep at it!
Glad you appreciate my content. The only serviceable part here is maintenance and good driving habits (which means you use the brakes less).
Since hybrids don't use brakes as much keep them serviced and well lubricated
@@speedkar99
Standard feature on all 70's vintage MOPAR vehicles operating in the Rust Belt. It became operational after 5 years of ownership.
Hi, if the máster cylinder have a leak on the part that goes to the pedal that's can go on a code C1391?
Pleasse help
U make an excellent instructor! Thank u, such a complicated system. U ask questions I THOT of, like a brushless motor. Who's toothbrush did u use THIS time? 😁 I cleaned/lubed my gen 4 caliper parts. I did alot of research before hand. Glad I did. U have to keep key fob away frm vehicle when pulling calipers. I'm very OCD when it comes to my brakes. Any way to extend life of actuator? I value ur opinion. 👍
Not really other than keep the brake fluid fresh
My car abs is started to light me in odo meter while lost the pressure and we dont know how ton sort it out
You are one smart dude.
Lol sure...
Thanks for the vid ! ... We want to see how hybrid cars works
You are welcome. Check out my hybrid videos linked in the video
Hello, is there a possibility to repair the actuator brake if there's leak? time to time I always refill a brake fluid
Do they sell any rebuild kits for these or is it just replace the whole assembly?
Woah, so what is the total "carbon footprint" on the manufacture of just one of these modern marvels? Too many pieces parts that make people cry when the service manager comes into the customer waiting area to "discuss" the repair cost that is 1/5th the price of a new car. Thinking I'm going out west and find a cherry 65 Ford Falcon to drive. "Simple by design", but now, will need a machine shop to make parts. Thanks Bro! You are the Master! Still not seeing a "Speedkar99" toothbrush in your store?
Hi I have a 2007 prius gen 2. When I press the brake pedal and car is stationary there is a squeeky noise. I only noticed it recently. What could it be please? Could it be worn discs/pads and brake bleeding or is it the master cylinder or worse the expensive part with electronics? There are no dash board lights but will there be error codes on OBD? Please help!
Just going to tell you that it doesn't always fail as intended!😳
Had a Toyota Avensis a work and the brake system failed intermittently completely with the valves locked.
It was like stepping on a brick and there was absolutely no brakes.
It was super scary and was extremely close to crash.
And many have complained about tesla brakes not working the same way
I just had this happen with my 2024 camry hybrid. I pressed the brakes and it felt like the pedal stopped half way but nothing happened. Toyota had someone to come and scan the event recorder for my car and he told me he didn't see anything. I believe he told me that he's sending the data to toyota but i need to find out. The car only has 2160 miles...
This was yesterday 12/29/2024.
In this system, if your ABS motor is running very frequently (compared to my other Lexus that use this same system), is it likely an issue of the accumulator holding pressure or would it be the whole assembly unit as that accumulator looks pretty simple. No lights yet, but have had the weird motor squeak now and then as well as the very very frequent running of the motor building pressure which doesn't seem to hold long before it's running again.
It's failing
What is name of these kind of brake system called
I had a code C1391 pop up on my R450. I replaced both the accumulator and actuator to the tune of nearly $2500. But when I watch this video, I wonder if I did the right thing, lol. Then again, so far, everything seems to be working on my RX and no warning lights have popped up. It's been nearly a month.
How do you turn off regen
Do you know what type of brushes in the motor or do you have a part number or a size?
No
thank you
You are welcome
Hi! What do you think about the v6 engine of the vw passat 2017? It's a good engine? What about show the teardown soon? Thanks!
The VR6? Would love to tear one down soon!
I have a hybrid rav4 and I assume since it doesn't use the mechanical brakes as often, that is why my brakes squeak when applied at lower speeds?
Mechanical brakes only work at lower speed. Service your brakes
4:13 what sort of food do they serve at these galleys?
Dobry kanał
If the brake motor runs every 10 seconds (with ABS light ON) after full flush with full synthetic is it fair to say that the accumulator has failed and it can be replaced or does the entire unit need to be replaced?
TLDR: Does the entire assembly require replacing, and if so is there a part number to look for for said exchange?
Yes. It has to be replaced as a unit of your brakes keep loosing pressure like that.
Have an '05 Prius. Brakes feel normal but they cut out over rough terrain like RR crossings. Any idea why that would happen? Great videos. Thanks.
Our 2017 does the same thing. It's really noticeable when braking going over a manhole cover or anything steel. My guess is the stability control is quite sensitive and because the brakes are so automated, the brake actuator releases the brake completely before attempting another application a fraction of a second later. It feels very weird because with conventional brakes this would not occur as the brake force you ask for, you get. The hybrid system probably wants to avoid any sort of wheel locking not just for safety but also because you cannot regen with a locked wheel. Hard to know for sure without getting info from the engineers who designed the system...
@@kiefershanks4172 That sounds very plausible. That's gen3 or 4? I'm kinda surprised they never addressed that. We get above 50 mpg around town. How is yours doing?
Gen 4. Great car. Pretty nice to be able to shrug off high fuel prices.
Where i can get all those oem parts on ABS Actuator
You'd be best replacing the whole thing from a junkyard car
The question is: will it be effective to replace the brake fluid (replacing all the brake fluid in the system) with the car turned off using a manual vacuum pump (by gravity)?
No. You'll need to cycle the brakes.
What causes the accumulator to come on to offen?
A leak in the system
hi the e-power note still uses a vacuum brake booster and every time the car thinks that braking might be required it starts the engine because why use expensive electronically boosted brakes when a vacuum booster is cheaper. (no corners were left un-cut) eg no rear speakers
What's an e-power note?
@@speedkar99 a e-power note is a nissan note that uses the e-power drive train (47kw 3 cylinder 1.2L motor acting as a generator and a separate 80kw electric motor to propel the vehicle)
@@davidmcclare443 Use caps.
Thanks
Welcome
You crack me up
Thanks for sacrificing parts for our learning. But I can't believe they use a brushed DC motor in a critical brake system. wow Toyota just wow
Yeah that seems odd
If they ever get additive manufacturing to be at the same cost/speed as regular manufacturing I could see car mfgs design a manifold without needing to drill oil galleries. You could probably make the part smaller and more compact too without being constrained by traditional manufacturing techniques. Of course if it ever gets clogged you have less access to clean.
Good thoughts. Additive manufacturing has come a long way, I think it has potential to be mass produced large scale soon
And when this fails in a hybrid Highlander you simply throw this wonderful comfortable car away.
This particularly painful if the problem has first been diagnosed by a well meaning tech as a dead battery and you put $2,500 into a reconditioned traction battery.
Then the car shutters while in park, won't charge, throws a bunch of codes and after towing to a dealer a 40 miles away and getting a "certificate of death" cost estimate estimate that you're not sure even solves the problem because it is so comolex, the whole thing becomes a sad experience and an expensive boat anchor.
Scotty kilmer is right. Do not a used buy hybrid if you want to keep the car a long time. This probably applies to EV s as well.
It's like when you must put down your favorite dog. You say, "I'll never do that again."
So why do hybrids not use classical ABS pump ?
This is essentially an ABS pump. It's just beefed up to also be a booster and add a few extra valves and solenoids
What could be the common faults + ways to prevent this
great video, ill have to watch a few time to fully understand it tho, I would love to know what Acura's hybrid braking system is like because my rlx sport hybrid has superior braking, I heard that it's so precise that the pads barely get worn down and last a lot longer than with a traditional braking system. Do you know anything about them?
I don't know anything about Acura superior braking. What's different about it?
@@speedkar99 I'll have to do some more research on it and let you. I have a 2018 acura rlx sport hybrid and they also use regenerative braking, that's all I really know
It's basically the same brake-by-wire concept as the Prius.
I need a stroke simulator.
Sure. I cut this one though
Dot 3,4 are good toothbrush cleaners too.
Good idea...
@@speedkar99 underwear and toothbrush technician-👍
At 07:35
What you call brake dust is most likely carbon dust from the brushes.
Stroke simulator? I had one of those when I was 11
And what happened to it?👀
@@speedkar99 I have outsourced those responsibilities. But it's still around here somewhere
Ok, looks like I'm not dealing with any future braking problems myself on my RX400h.
Prius owners: “Nice spongey pedal feel”
These systems do a terrible job at providing pedal to braking force linearity, there has got to be a better way
Well most manfactures are skipping it and going digital
@@speedkar99 the Prius system is exactly that. Digital brakes.
I just rebuilt my son's 2011 lexus is250 front brake calipers, replaced the brake pads w/ akebono pads and replaced the rotors. Not gonna happen with my wife's 2021 toyota rav4 hybrid xle, too complicated.
You can change the brakes like normal cars. You might just need the scan tool to reset everything to get it right.
Что мешало так сделать на всех машинах, зачем костыли в виде вакуумного усилителя. Данное решение это abs, brake, esp, hsa,tcp в одном флаконе
1.8 prius 2012
Yes
its a gen2 prius brake system
Yes
Not what I was looking for.
do yourself a favor and set the video to custom playback speed of 0.9x. Great video though!
Stroke simulator. Huh that's the same thing that I told my wife that we were going to do last night
And what happened??
@@speedkar99 a gentleman would never kiss and tell
You forgot to mentioned who's toothbrush is this.. :(
Sorry. Colgate is my brothers. My wife used oral B
@@speedkar99 hahahahaha, you are a very nice person... Thanks for the video.. didnt know the hybrid break system doesnt have booster and vacuum hose..
No wonder old prius brakes feel so weird, very strange braking system with a lot of simulation and switchover between systems.
Yep the switchover is noticable
but ... why did the pig crossed the road?
To avoid the Prius 🤣
very interrsting tanhks
All this to replace missing engine vacuum. I would have just added a vacuum can and a small vac pump. Problem solved with low tech.
Universal hex removal tool 😂
Zip
hmm wonder what hes doing with these parts... bet he sells them on Ebay after the video is ove...REEEEEEEEEEeeRRErREEERRREREER ... hmmm maybe he sells the metal for scrap. :o) 🐔
oil gal-ler-ries.
Galleys galleries lol I keep mixing up
@@speedkar99 don’t change a thing! ;)