How many moving parts in a Model S

[Larry93428]

Counting moving parts is an OK way to compare the two systems but virtually every moving part in a Tesla spins. ICE has many reciprocating parts - things shaking up and down or back and forth - that must be converted to rotation. The ICE must be internally balanced to reduce vibration and wear that BEV never experiences.
And the many geared transmissions now-a-days, wow!
~Larry

 

[castor]

I would like to know roughly where are the 2000 parts on a ICE powertrain, since if I'll go with an argument with someone then I can't take 2000 parts number from my hat.

If the Model S motor is counted as one moving part (no bearings or gears?) then probably ICE engine should be count as one part as well?

For a moment let's leave Tesla shirt on a side, can you name more than 200 parts on an ICE drivetrain? I need to know this to win arguments with facts.

 

[ggr]

I would like to know roughly where are the 2000 parts on a ICE powertrain, since if I'll go with an argument with someone then I can't take 2000 parts number from my hat.

If the Model S motor is counted as one moving part (no bearings or gears?) then probably ICE engine should be count as one part as well?

For a moment let's leave Tesla shirt on a side, can you name more than 200 parts on an ICE drivetrain? I need to know this to win arguments with facts.

For each cylinder, there are four valves, each of which has various seals and clips and springs, and shims on the camshafts, and the cylinder itself has a connecting rod with bearings at both ends, the piston, multiple piston rings. Then there are gears that drive camshafts, and counterweights, and the various bearings for all of these. Oh, and the camshafts have variable timing these days, so there are gears and things to do that. Lubrication: oil pump(s), gears, seals. Coolant pump(s) with gears and seals. Fuel pump. I don't find 2000 unbelievable at all. (The more I think the more things I come up with... turbocharger, fuel injector valves, bits in the generator/alternator (all 14! ), starter motor and engagement gears, ...)

 

[sandpiper]

I would like to know roughly where are the 2000 parts on a ICE powertrain, since if I'll go with an argument with someone then I can't take 2000 parts number from my hat.

If the Model S motor is counted as one moving part (no bearings or gears?) then probably ICE engine should be count as one part as well?

For a moment let's leave Tesla shirt on a side, can you name more than 200 parts on an ICE drivetrain? I need to know this to win arguments with facts.

I couldn't name them all, but 2000 parts wouldn't surprise me if you consider each bearing, snap ring, linkage arm, actuator, spring, pin, solenoid, valve, etc.... There are a lot of little bits and bobs in every single subsystem.

 

[castor]

For each cylinder, there are four valves, each of which has various seals and clips and springs, and shims on the camshafts, and the cylinder itself has a connecting rod with bearings at both ends, the piston, multiple piston rings. Then there are gears that drive camshafts, and counterweights, and the various bearings for all of these. Oh, and the camshafts have variable timing these days, so there are gears and things to do that. Lubrication: oil pump(s), gears, seals. Coolant pump(s) with gears and seals. Fuel pump. I don't find 2000 unbelievable at all. (The more I think the more things I come up with... turbocharger, fuel injector valves, bits in the generator/alternator (all 14! ), starter motor and engagement gears, ...)

Thanks, that's a good start for a M5 engine which is what a Model S is compared to, also the argument is about moving parts, lets not count fluids and seals, since the Model S also have these and parts that don't move don't count for the argument.

Just the engine interior
4 * 8 = 32 valves?
32 springs?
8 pistons?
bearings 2?
24 piston rings?
1 Crankshaft?
8 Connecting rod?
32 clips pins?
8 piston pins?

147 parts, still long way to 2000.

May be in the transmission another 200 or 300?

Probably 2000 is about the number of total parts and not about the moving parts for which we have to compare to the Model S number of parts in the drivetrain as well, however if we just compare the number of parts the Model S powertrain already have 7000 batteries to sum quickly to the count.

Probably the Model S is at least 10 times less moving parts however is not 14, 18 or 20, so people should be careful when make these statements because sound foolish.

 

[romp]

While I don't think there's strong correlation between the number of parts and reliability (we should also consider maturity of the technology, tolerances, working conditions, interoperability requirements, etc.), but still. Lets compare one moving shaft in AC induction motor with this (BMW S54, a fine example of naturally aspirated, and therefore simpler due to the lack of turbo and intercoolers, engine):

My uneducated count came up with 22 *moving* parts per cylinder (6 cylinders in this case) + 12 common moving parts + starter + generator + oil pump + some other pump-looking thingy, each of which has several moving parts in them. So, at least 148 moving parts in the engine alone, probably more if you count components in the starter/generator/pumps. Each of which has wide range of working temperatures (and therefore tolerances) and atmospheres (air, fuel mixture, combustion products, oil, coolant, etc).

The transmission comparison is less dramatic, but somewhat similar.

 

[PV4EV]

There's probably 10,000+ physical parts within a Model S but the key distinction is that less than 1% move, whereas a V12 or whatever has literally thousands of moving parts to go wrong. It still amazes me that the mass of a piston & con-rod can reciprocate 100+ times a second under massive swings in pressure, heat, explosions, cold air etc.

Unfortunately in my past I've had various V8s start smoking (let alone go bang big time), often needing a strip down to replace just one tiny item like a split neoprene seal on a valve stem causing an excess of oil to leak into a cylinder producing blue smoke out the back! The seal might only cost $1 but labour will be $ X0,000 and the rest. And that's annoying. I'm sure we've all been there !!

Things like cam chains have hundreds of tiny links and bearings pins, which can catastrophically damage the engine if just one link breaks. Cam chains alone could significantly add to the guesstimated 2,000 moving parts.


Meanwhile here's a couple of photos to remind us of the good old days. I'm not counting the parts though ..

(edit .. Someone above beat me to it with the exploded engine photo !!!)

 

[jerry33]

That may be true, but even with a small number of moving parts, it will be a while before the reliability is appreciably better than with an ICE. I've only been on these forums for a few months, but anecdotally it seems to me that the MS is no more reliable than a good quality ICE car.

I wasn't really referring to the number of parts, more to the modularity of them. In most cases a failure in a Tesla means replacing a module or a simple part.There isn't, for example, the machining that ICE engines require when being rebuilt, nor are there any timing functions to get wrong. Even those Service Centres that are replacing the contactor in the battery are basically just unbolting and attaching a couple of wires. The mechanically complex* pieces on the Tesla are the doors, presumably the reduction gear when SCs start to repair them, and the suspension. The software is also tricky, but since that doesn't normally require a shop visit, it's a non-issue for most folks.

*Complex in this context means they have to be fiddled with to get right.

 

[bluenation]

ICE is a beautiful, mature, sonorous, antiquated, and deeply inefficient belle of the dance floor. Unlike most ppl in this forum, i will forever admire her.

EVs however, hold the promise of finally breaking the paradigm: cheap, fast, reliable, choose any two.

We are not there yet, but in a matter of half a decade or so, we will. And that makes EVs special.

 

[EVBeast]

Something that should be considered: At the end of World War II, piston/propeller aircraft reached its peak development where they had turbo-superchargers, water injection, and a number of other seriously advanced technologies deployed and working reliably.

At the same time, the early jet engines were slow to spin up, had overheating and reliability problems, and sucked through fuel very quickly (thus had a very short range).

But, jets had far more promise, and in the medium to long-term ended up dominating the aviation industry. Most people feel comfortable flying in jets (more reliable) than prop/piston planes these days, and that's for a reason.

I figure we're at the point where ICE technology has peaked, and there's not much more that can be done to improve an ICE engine. EVs and battery improvements are going to quickly surpass the ICE environment. I'm figuring that in 5 years, there will be a new battery that will permit 500 miles of range, and in 10 years, you can get a 1,000 mile battery. Why would anyone buy an ICE then?

 

[SteveS0353]

[snip]
It still amazes me that the mass of a piston & con-rod can reciprocate 100+ times a second under massive swings in pressure, heat, explosions, cold air etc.
[snip]

That's a very large difference which gets glossed over more often than not. The Model S has a small number of rotating parts, not a large number of reciprocating parts that literally stop and change directions a couple of hundred times per second. The forces are enormous, and with decades of engineering, RICEs have become pretty sophisticated and reliable, albeit noisy, smelly and inefficient beasts. With more engineering and refinement, particularly on the evolving battery technology, electric vehicles powered by rotating induction motors hold great promise for superb reliability, surpassing RICE reliability, and without the noise and smell, and with terrific efficiency.

Edit. To clarify, I've used the specific initialism "RICE" (Reciprocating Internal Combustion Engine) being the overwhelmingly common power plant in automobiles today, but there are other types of ICEs that don't have reciprocating parts, e.g., the Wankel Rotary engine found in some Mazda sports cars, and the Sarich Orbital engine. Both have their unique problems, like wear of the rotor tips in the Wankel, and lubrication and cooling of the Sarich. I firmly believe the 3-phase induction motor will eventually retire all ICEs to museums as marvelous examples of human ingenuity and evolutionary engineering. Bravo Tesla (Nikola, that is)!

I'm all in!!!

 

[neroden]

Well, then, shall we count the reciprocating parts in a Model S?

-- Air compressor for HVAC system
-- Air compressor for air suspension (which is an option, of course)
-- Compressor for brakes (for older cars, new cars don't)

I think that's three examples of piston motion. Or is Tesla using non-reciprocating compressor designs for these?

 

[chickensevil]

Well, then, shall we count the reciprocating parts in a Model S?

-- Air compressor for HVAC system
-- Air compressor for air suspension (which is an option, of course)
-- Compressor for brakes (for older cars, new cars don't)

I think that's three examples of piston motion. Or is Tesla using non-reciprocating compressor designs for these?

Yeah, but I think all of these are the same for other cars too. So it really isn't putting Tesla in a better (or worse) condition here. The only *new* thing would be the heat pump which is totally not needed in an ICE. So I suppose that is one new thing that could fail...

As for the brakes, does it actually remove the hydraulics? I wasn't sure if the brakes were moved into a fully electric braking system or if it was the hybrid style that does like a mix of both. If it is a true 100% electric braking system then that would be an industry first in a production car as best I could tell. Because there was a lot of issue guarenteing some kind of safety should the system fail. If you lose brake fluid... all you have to do is press the bakes *really* hard and you should be able to still get *some* amount of stopping power, but if the electric brakes fail... my understanding is that you would be pretty much dead in the water... no stopping power.

The "counter" safety that only an electric car would be able to provide that might make it proof of a safer system all around is that should the system detect total brake failure it can fall back on the regen-braking as a means to bring the car to a stop, and theoretically in a failure state the car could override the "standard" regen, into a "super-regen" exceeding the max-G limiter on the regen-stopping power (as in ride out at 60kW until coming to a full stop) and override the 5MPH cut off that would allow it to fully stop the car. Anyway... it would act as a backup-emergency braking system which should get past some of the safety regulations that have locked us into hydraulic braking for such a long time.

 

[castor]

Yeah, but I think all of these are the same for other cars too. So it really isn't putting Tesla in a better (or worse) condition here. The only *new* thing would be the heat pump which is totally not needed in an ICE. So I suppose that is one new thing that could fail...

As for the brakes, does it actually remove the hydraulics? I wasn't sure if the brakes were moved into a fully electric braking system or if it was the hybrid style that does like a mix of both. If it is a true 100% electric braking system then that would be an industry first in a production car as best I could tell. Because there was a lot of issue guarenteing some kind of safety should the system fail. If you lose brake fluid... all you have to do is press the bakes *really* hard and you should be able to still get *some* amount of stopping power, but if the electric brakes fail... my understanding is that you would be pretty much dead in the water... no stopping power.

The "counter" safety that only an electric car would be able to provide that might make it proof of a safer system all around is that should the system detect total brake failure it can fall back on the regen-braking as a means to bring the car to a stop, and theoretically in a failure state the car could override the "standard" regen, into a "super-regen" exceeding the max-G limiter on the regen-stopping power (as in ride out at 60kW until coming to a full stop) and override the 5MPH cut off that would allow it to fully stop the car. Anyway... it would act as a backup-emergency braking system which should get past some of the safety regulations that have locked us into hydraulic braking for such a long time.

The regen is an option, however if the car can detect the brakes are not operational easily I'm sure they can feed the motor reverse energy (similar when going backwards), and make a full stop similar or even better than with the hydraulic brakes. I don't know if a system like that exists on the ModelS.

 

[chickensevil]

The regen is an option, however if the car can detect the brakes are not operational easily I'm sure they can feed the motor reverse energy (similar when going backwards), and make a full stop similar or even better than with the hydraulic brakes. I don't know if a system like that exists on the ModelS.

My understanding of that is they quite literally run the motor backwards for reverse.

So the problem as I see it of doing this is that the motor is currently running at something like 7,000 RPMs at around 70MPH, or around 3,000 RPMs at 30 MPH, if you tried to reverse the spin of the motor, you would first have to stop the forward spin, and then make it spin in reverse. The most efficient means to stop the forward spin is activate regen since that takes the mechanical motion and turns it back into electricity. So by the time you have stopped spinning the motor forward you would be stopped on the road... You don't need to throw it into reverse because the car would be stopped already right?

I am going to guess that reverse changes the polarity of the motor to have electrical energy apply spin on the motor in the opposite direction. It may be possible to burn electrical energy on this reversed polarity to also slow down the motor quickly? I don't know what the impact on the system would be to do that to your motor. Would it cause damage?

I would think it would just be easier to change the restrictions on regen to apply a stronger braking power.

 

[castor]

My understanding of that is they quite literally run the motor backwards for reverse.

So the problem as I see it of doing this is that the motor is currently running at something like 7,000 RPMs at around 70MPH, or around 3,000 RPMs at 30 MPH, if you tried to reverse the spin of the motor, you would first have to stop the forward spin, and then make it spin in reverse. The most efficient means to stop the forward spin is activate regen since that takes the mechanical motion and turns it back into electricity. So by the time you have stopped spinning the motor forward you would be stopped on the road... You don't need to throw it into reverse because the car would be stopped already right?

I am going to guess that reverse changes the polarity of the motor to have electrical energy apply spin on the motor in the opposite direction. It may be possible to burn electrical energy on this reversed polarity to also slow down the motor quickly? I don't know what the impact on the system would be to do that to your motor. Would it cause damage?

I would think it would just be easier to change the restrictions on regen to apply a stronger braking power.

What I mean is the question if the Model S provides an emergency and redundant system for the brakes, the Model S can easily detect if the hydraulic system has failed, when the user press the brake it can trigger a failsafe mechanism that really "reverse the polarity" in some degree (it is an AC motor so is more probably about controlling the phases and voltage). Even if you put the motor in shortcut (equivalent to MAX REGEN possible but not real) I don't think will be enough resistance to produce a decent quick stop, "reversing the polarity" doesn't mean the motor will spin backward but the two forces will counter each other and will decrease the speed in a controlled manner. Similar principle than ride a steep downhill on a low gear on a ICE engine.

 

[TomE]

There are some things about induction motors which might not be obvious:
1. The rotor is a large rotating mass with only two bearings. Any imbalance or shaft bending is going to stress the bearings periodically. If the stator windings or rotor bars are not exactly symmetrical or the three phase AC drive current not balanced then there will be unbalanced magnetic force acting on the rotor - more bearing stress.
2. All the motor torque is transmitted by the rotor bars to the rotor core, and the torque reaction is applied be the stator windings to the stator slots. The instantaneous torque varies with the AC drive frequency, so the stator winding are being rattled around at 50 Hz to 400 Hz. They had better be wedged in there tightly.

Also the electrical circuits (bus bars, fuses, HV joints, IGBTs, contactors, etc.) are subject to thermal cycling as the driver's right foot operates the accelerator pedal.

All these parts (and more) are not moving, but they are still subject to cyclic stress - this is what causes failure. A moving part not subject to a lot of stress will last forever.

 

[PV4EV]

What I mean is the question if the Model S provides an emergency and redundant system for the brakes, the Model S can easily detect if the hydraulic system has failed, when the user press the brake it can trigger a failsafe mechanism that really "reverse the polarity" in some degree (it is an AC motor so is more probably about controlling the phases and voltage). Even if you put the motor in shortcut (equivalent to MAX REGEN possible but not real) I don't think will be enough resistance to produce a decent quick stop, "reversing the polarity" doesn't mean the motor will spin backward but the two forces will counter each other and will decrease the speed in a controlled manner. Similar principle than ride a steep downhill on a low gear on a ICE engine.

Interesting problem !


Stopping a car travelling at, say, 70mph, when the brakes have failed, involves dealing with a lot more energy than the regen system can handle.

We know that the Model S with one driver on board weights approx 2,200 kg.

The kinetic energy at 70mph is KE=0.5 x Mass x Velocity ^2.

This works out at 1,077,659 Joules. That energy must be dissipated or stored somehow in order to bring the car to a halt.

If the process takes approx 4 seconds to grind to a halt, the rate of energy dissipation is (loosely speaking ) 270,000 joules per second, or 270kW.

But, in reality this is not a linear function, more exponential, and usually its dissipated as heat into the brake discs with a peak rate more like 400kW.

The maximum Regen of the Model S is shown as 60kw, not including various losses along the way. So, assuming the car was doing 70mph and you went into max regen braking slowly to a halt, it would take the Model S regen system (loosely speaking ..) about 15+ seconds to come to a halt (includes some losses to rolling resistance, aero losses etc). Next time you're driving try it out !


However, electrically storing or dissipating 400 kW momentarily is altogether a different problem to solve with some fairly beefy electrical engineering required.

This is one area where an ultra capacitor assembly could be used to harvest the energy. Based on my direct experience of using large ultracaps, I would guesstimate the weight penalty for the car to have a ucap regen system would be around 40-50kg, and probably add $7,500 to the cost of the car! But the major plus point of doing it this way would be that 95% of the harvested braking energy could be re-used the next time the car accelerates, or it could possibly be augmented into the energy of the battery pack. But if Tesla were to include Ucaps with the battery system, it would require some significant changes to the way the energy system works, and the load levelling effect would de-stress the battery pack and lengthen its usable life.

Whilst not simple in practice, it can be done. China now has thousands of ultra capacitor buses that spend all day accelerating / braking between bus stops a mile or two apart and they are amazingly energy efficient over the course of the day.

 

[chickensevil]

The maximum Regen of the Model S is shown as 60kw, not including various losses along the way. So, assuming the car was doing 70mph and you went into max regen braking slowly to a halt, it would take the Model S regen system (loosely speaking ..) about 15+ seconds to come to a halt (includes some losses to rolling resistance, aero losses etc). Next time you're driving try it out !

Testing this yourself will not provide the correct stopping time on an emergency system which uses just the 60kW regen. This is because once you get below about 30MPH (maybe slightly higher) it tapers back the max regen as the speed slows. This is because there is a maximum g-force limiter put in place and tied to regen such that, letting off the accelerator at 15MPH doesn't feel like you are slamming on the brakes (which is what it would feel like if you were drawing 60kW of power back instead of the 30kW or so...)

So at low speeds (sub 30) the emergency braking by strictly using regen built into the car might actually be sufficient braking power to provide adequate enough stopping power. The point of this way off topic discussion had to do with being a backup system in the event of a true electro mechanical braking system failure... This should never happen in the first place... but if it does, you simply need to detect the failure and forcibly override the car's systems bringing you to a halt in a safe fashion. It isn't to be an emergency brake in the sense of avoiding an accident, merely providing *some* means to hopefully stop the car and then get it towed somewhere for repair. I don't think there is anyone out there that could use enough manual power in the event of hydraulic failure to *equal* the braking power of having a properly working hydraulics... it is merely something to allow you *some hope* of stopping the car. So all it needs to be is *better* than the current manual override in current braking systems in order to be allowable to replace hydraulics. I think they can prove that using just the regen on the car.

The final outcome would be the complete removal of hydraulics in the car, which would be one less fluid to maintain and one less mechanical system to break.

 

[joeinslw]

(LMB spouse)

24 seems pretty low. There are 18 just associated with the wheels and drive shafts:

4 x (wheel shaft + 2 wheel bearings) plus 2 x (drive shaft + 2 CV joints).

And that's not even counting brake parts.

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If you doubt what I quoted i.e. about the 18 moving parts, then ask yourself why did GM crush their own electric cars in 1999 when the people who leased them were begging GM to buy them, but GM refused ? WHY ???? The answer to me is obvious, and should be to you as well.