Do not be scared of using that charge button.

[maby]

As far as I am aware, the Prius has a CVT and planetary gear. That is a variable gear train, AKA gearbox.

it does not have anything that I would describe as a gearbox...

Toyota would .... (http://blog.toyota.co.uk/how-does-toyota-hybrid-synergy-drive-work):

Toyota’s Hybrid Synergy Drive system is comprised of six primary components: a petrol engine, an electric motor, an electric generator, the power control unit, and a power split device that uses a special type of gearbox to smoothly distribute power from the engine, motor and generator.

Well, the thing in the middle of the axle on a conventional car contains multiple gears, but I don't describe it as a "gearbox", do you? There is nothing in the Toyota hybrid drive train which contains multiple gears and implements multiple drive ratios - either fixed steps or continuously variable - by switching different gears in and out of the power train or by moving bands on cones or other weird shapes. It's a three port, fixed ratio differential - admittedly using a planetary gear arrangement to reduce the physical size rather than crown gears, but functionally exactly the same as the lump in the middle of an axle.

 

[anko]

Well, the thing in the middle of the axle on a conventional car contains multiple gears, but I don't describe it as a "gearbox", do you? There is nothing in the Toyota hybrid drive train which contains multiple gears and implements multiple drive ratios - either fixed steps or continuously variable - by switching different gears in and out of the power train or by moving bands on cones or other weird shapes. It's a three port, fixed ratio differential - admittedly using a planetary gear arrangement to reduce the physical size rather than crown gears, but functionally exactly the same as the lump in the middle of an axle.

Who says a gear box must implement multiple drive ratio's? You can put a lot of effort in describing how it works (again), but I think that is not wat we disagree on. We disagree on the name. If it is okay with you, I stick with what Toyota says .

BTW: if you use a light switch to turn on or off the ceiling fan, do you still call it a light switch?

 

[maby]

Well, the thing in the middle of the axle on a conventional car contains multiple gears, but I don't describe it as a "gearbox", do you? There is nothing in the Toyota hybrid drive train which contains multiple gears and implements multiple drive ratios - either fixed steps or continuously variable - by switching different gears in and out of the power train or by moving bands on cones or other weird shapes. It's a three port, fixed ratio differential - admittedly using a planetary gear arrangement to reduce the physical size rather than crown gears, but functionally exactly the same as the lump in the middle of an axle.

Who says a gear box must implement multiple drive ratio's? You can put a lot of effort in describing how it works (again), but I think that is not wat we disagree on. We disagree on the name. If it is okay with you, I stick with what Toyota says .

BTW: if you use a light switch to turn on or off the ceiling fan, do you still call it a light switch?

OK - I'll grant you that, but this digression began when you questioned my statement that "For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time." I would maintain that the Toyota drive train qualifies as having "virtually no gearbox" - there is a device in the drive train that contains physical gears, but it does not fulfil the accepted function of a car gearbox in that it varies the drive ratio in the power train by either swapping gears in and out or by varying the diameter of some drive component. The thing that I value in a hybrid car is the simplicity of the drive train. Over the course of my driving career, I have suffered far too many failures of gearboxes and clutches, so the knowledge that all the drive train components are permanently in mesh is very reassuring!

P.S. personally I would not describe it as a "light switch" - it is either the "fan switch", or more probably just "the switch"

 

[anko]

... this digression began when you questioned my statement that "For me the primary reason for buying a hybrid (apart from the tax concessions) is mechanical simplicity - virtually no gearbox, virtually no clutch, and an engine that is ticking over most of the time."

I don't think I questioned that statement. I believe what I said was that, in order to allow the ICE to drive the wheels directly at all speeds, the Prius needs more of a gearbox than the PHEV does, which doesn't allow the ICE to drive the wheels at low speed. So, you can't have it both ways. I thought you would agree with me. But somehow, you wouldn't allow it. Don't know why.

I would maintain that the Toyota drive train qualifies as having "virtually no gearbox" - there is a device in the drive train that contains physical gears, but it does not fulfil the accepted function of a car gearbox in that it varies the drive ratio in the power train by either swapping gears in and out or by varying the diameter of some drive component.

Accepted by whom?

P.S. personally I would not describe it as a "light switch" - it is either the "fan switch", or more probably just "the switch"

So, when something that can function as a light switch can also function as a fan switch, then something that functions as a differential can also function as a gearbox, right. What is the problem really? :lol:

 

[maby]

.....

P.S. personally I would not describe it as a "light switch" - it is either the "fan switch", or more probably just "the switch"

So, when something that can function as a light switch can also function as a fan switch, then something that functions as a differential can also function as a gearbox, right. What is the problem really? :lol:

you remind me of an old college friend who specialised in philosophy. He spent a long time explaining to me that the phrase "a broken clock" was meaningless - a "clock" is defined to be a device that tells the time and if a device of the physical characteristics of a clock has a fault which means that it does not tell the time, then it does not qualify for the description "clock" ... :lol:

 

[anko]

you remind me of an old college friend who specialised in philosophy. He spent a long time explaining to me that the phrase "a broken clock" was meaningless - a "clock" is defined to be a device that tells the time and if a device of the physical characteristics of a clock has a fault which means that it does not tell the time, then it does not qualify for the description "clock" ... :lol:

:lol:

 

[greendwarf]

you remind me of an old college friend who specialised in philosophy. He spent a long time explaining to me that the phrase "a broken clock" was meaningless - a "clock" is defined to be a device that tells the time and if a device of the physical characteristics of a clock has a fault which means that it does not tell the time, then it does not qualify for the description "clock" ... :lol:

:lol:

Except that of course even a "broken clock" - if it has its hands - still tells the time, just the wrong one apart from twice a day when it momentarily tells the correct time. :lol: :lol:

 

[anko]

you remind me of an old college friend who specialised in philosophy. He spent a long time explaining to me that the phrase "a broken clock" was meaningless - a "clock" is defined to be a device that tells the time and if a device of the physical characteristics of a clock has a fault which means that it does not tell the time, then it does not qualify for the description "clock" ... :lol:

:lol:

Except that of course even a "broken clock" - if it has its hands - still tells the time, just the wrong one apart from twice a day when it momentarily tells the correct time. :lol: :lol:

Sure about that? :idea:

 

[elm70]

Anyhow ... what is the end conclusion between eCVT from Prius and single gear from our PHEV ?

Which one is the most simple and reliable system ?

My bet is that our PHEV is more simple and reliable ... while the Prius has a more efficient transmission
I also bet our PHEV transmission system is also cheaper to be produced

As well .. as far as I know ... one of the two eMotor from Prius is a brushless motor with brushes ... so it may eventually need maintenance .. while the eMotor in our PHEV are maintenance free

 

[anko]

... is a brushless motor with brushes

That makes me curious .... Just a typo? Or is an explanation in order?

 

[elm70]

... is a brushless motor with brushes

That makes me curious .... Just a typo? Or is an explanation in order?

If I understood correctly the Prius transmission system, one of the two eMotors , not only the internal rotor can spin, but as well, the full motor itself can spin (this is the trick for have a eCVT)

Logically these are all "Brushless" motors (3 phase AC motors), but in order to provide the 3 phases to a spinning motor it is needed to have 3 "brushes" , one for each of the 3 phase

 

[anko]

I see what you mean. If the below schematic picture is correct, the main axle coming from the ICE runs through MG1 freely, but that should mean MG1 needed to spin as a whole. Or am I missing something here?

Something similar happens in the Ampera E (Bolt EV). The e-motor uses a hollow axle to connect to the diff (via a set of reduction gears). One of the drive shafts (I think the left one) runs from the diff to the wheel through that hollow axle:

 

[elm70]

Per my understanding .... yes, MG1 is the one that need to be spinning as whole ... if needed ... this MG1 can work as reduction or even as booster based if it is used as partial generator or extra power provider (but I guess they don't use ...

 

[anko]

Per my understanding .... yes, MG1 is the one that need to be spinning as whole ... if needed ... this MG1 can work as reduction or even as booster based if it is used as partial generator or extra power provider (but I guess they don't use ...

In case of the Bolt / Ampera construction: When the e-motor is stopped, the right and left drive shaft spin at the same RPM but in the opposite directions. By making the e-motor spin (not the motor, just the rotor), you can change the RPM of the right drive shaft more or less independently from the RPM of the left drive shaft.

Now imagine the differential in the picture serves as the power splitter, the left drive shaft is axle from the ICE and the right drive shaft is axle leading to actual diff. Then the e-motor can be used to increase / reduce RPM of the axle going to the diff without changing the RPM of the ICE. No need to spin the whole e-motor. Or is there?

 

[elm70]

Per the picture you posted, the power split device is after MG1

Also ... per a video I have seen explaining the Prius transmission, it was clearly shown and stated that one of the two eMotor has to fully rotate in same scenarios

I know the Prius transmission got updated 2 or 3 times .. not sure this "feature or limitation" is something valid in the past or it is still valid now

 

[anko]

Per the picture you posted, the power split device is after MG1

Indeed. As the differential is after the single e-motor in the Bolt.

 

[maby]

Per the picture you posted, the power split device is after MG1

...

That picture is misleading - the power split device is a three port differential with two of the ports coaxial on the left hand side of the picture as it is shown above. The output shaft of the petrol engine is directly coupled to the central shaft of the differential and the MG1 motor-generator is mounted coaxially around the engine output shaft, coupled to the second port of the differential which is presented as a sleeve round the central shaft. MG1 is a pretty standard electric motor except for the fact that its output shaft is hollow to allow the petrol engine output shaft to pass through it.

It is certainly the case that the Toyota hybrid package contains more moving parts than the PHEV, but they are all in permanent mesh. Don't get me wrong - I don't violently dislike the PHEV drive train - though I would prefer that it did not have a mechanical clutch buried quite deep inside it. For my pattern of usage, I do prefer the Toyota power management approach and that would not be possible to implement with the PHEV drive train. The Toyota drive train has been around for a long time now and there are Priuses with high mileages on the road that are not breaking down, so they must have got it pretty much right.

 

[anko]

Dobrin Nedev reported some interesting observations on the PHEV Watch Dog Facebook page (https://www.facebook.com/groups/152278275319772/permalink/231069477440651/?comment_id=233199113894354&notif_id=1524058976021492&notif_t=group_comment_follow&ref=notif), w.r.t. the use of Chrarge mode at higher speeds:

Dobrin Nedev A little bit more info. I tried 130-140km/h with charge button.

130km/h ~ -8kW on flat, changing from -12kW to +3kW when the steepness slightly changes. Burns constant 11.6l/100km, which does NOT change when the steepness slightly changes.
Most probably on 130km/h the ICE still has some free power till those 75% Anko mentions. So, it burns the same fuel but changes the load of the generator depending on the steepness.

140km/h ~ -12kW constant, no matter the slight changes of steepness. Burns around 14l/100km on flat but this time this is not stable, it changes depending on the steepness.
Maybe here already the engine needs to go over the 75% but strangely the car decides to keep the load of the generator constant and increase the fuel rate.

This seems to confirm that the PHEV is well capable of adding charge to the battery, even at speeds of 110 km/h and well above.

 

[elm70]

Thanks Anko .... very interesting numbers

So at 130km/h @ 11.6L / 100km ... with 8kw recharge

It means in 1 hour 15L of fuel are consumed .. 130km done .. and battery almost fully charged from empty .. which we can state as extra 25km/30km in EV mode at 130km/h

Summing up .. per my calculation it means a real consumption between 9.4L to 9.7L every 100km @ 130km/h speed .. which as we know .. it is not really brilliant ... but yes, our PHEV is not born for cruise on autobahn

PS: I still have to check if B0 to B5 make any difference on recharge when ICE is used

 

[anko]

which we can state as extra 25km/30km in EV mode at 130km/h

25 / 30 km on 8 kWh @ 130 km/h seems a bit optimistic ;-)

Summing up .. per my calculation it means a real consumption between 9.4L to 9.7L every 100km @ 130km/h speed .. which as we know .. it is not really brilliant ... but yes, our PHEV is not born for cruise on autobahn

True. But rather than looking at absolute values, in context of this topic I would be more interested in effect of hysteresis cycle versus parallel mode without recharging. Two problems:
- above 125 km/h we have no hysteresis cycle
- below 125 km/h, it is difficult to know fuel consumption without charging

Yet, I have asked Dobrin if he noted fuel consumption @ 130 km/h without Charge mode.

PS: I still have to check if B0 to B5 make any difference on recharge when ICE is used

My guess is there will be no effect until you start coasting in charge mode. In B1 or higher, the ICE will start idling (at the expense of a little fuel). In B0 the ICE will continue to charge the battery full speed (at the expense of much more fuel). I have used this knowledge, when trying to maximise SOC during coasting: make sure to switch to B0 before letting go of the throttle. Interrupting CC also cause charging to stop as you will be at least in B2 when using CC.