Hybrid - engine stop/start - Engine life

[polk123]

Hello

Engine life longevity with a hybrid car.

So a hybrid car will switch off the petrol engine and start running on Battery when ever it can.

So all this constant turning-off and restarting the petrol engine, many, many times even on a short trip. 

What effect does this have on engine life. As you know most of the engine wear and tear occurs when it starts up and the oil pressure builds up.

Thanks

[Zotto]

This is a reason more to have 0W-20 oil in hybrid. About engine life, consider that it works for almost half  time compared to a traditional car, so the real miles with engine are less

[NemesisUK]

Does the hybrid ICE have an electric oil pump?

[royoftherovers]

The IN CAR  ENTERTAINMENT SYTEM (ICE)  DOES NOT REQUIRE AN ELECTRIC PUMP PETER.

Please define ICE.

 

Regards

John

[steveledzep]

Internal Combustion Engine......ICE

[NemesisUK]

Does the ICE (Internal Combustion Engine, royoftherovers ) actually stop spinning when the electric motor takes over? Obviously when stopped at lights it does but when cruising?

[Zotto]

Absolutely NO. The thermal and electric work in synergy, thermal engine goes off only under 70 km/h (about 50 mph) and in deceleration, or is kept off in acceleration only if the requested power from standstill is low so to permit only electric.

[royoftherovers]

15 hours ago, NemesisUK said:

Does the ICE (Internal Combustion Engine, royoftherovers ) actually stop spinning when the electric motor takes over? Obviously when stopped at lights it does but when cruising?

Nemesis,

Mine is a Generation 3 GS 450h and the Energy Monitor Display shows that the engine is not contributing anything at all whenever I lift my foot off the accelerator. In these circumstances it shows that it is the elecric motor that is powering the car.

Regards

John

[NemesisUK]

34 minutes ago, royoftherovers said:

Nemesis,

Mine is a Generation 3 GS 450h and the Energy Monitor Display shows that the engine is not contributing anything at all whenever I lift my foot off the accelerator. In these circumstances it shows that it is the elecric motor that is powering the car.

Regards

John

As does the monitor in my RC but the question stands, does the ICE still spin (free-wheel, no ignition spark, no fuel being consumed ) even when not providing power to move the car? If it does it would continue to maintain oil pressure and reduce wear from constant start-ups?

I noticed in this cold snap we're experiencing that the ICE fires up to provide warmth to the cabin (and it's own internals?) even though the monitor shows the electric motor is providing power to the wheels. No other indication i.e. powerflow, from ICE to the wheels.

[polk123]

Anyone got a the Torque App, this should provide more engine info then the standard display.

The rev counter (if u have one) should be another indicator of whether the engine is running or not.

Or a wireless camera mounted inside the bonnet to see movement of pulleys, belts, etc.

[Britprius]

1 hour ago, royoftherovers said:

Nemesis,

Mine is a Generation 3 GS 450h and the Energy Monitor Display shows that the engine is not contributing anything at all whenever I lift my foot off the accelerator. In these circumstances it shows that it is the elecric motor that is powering the car.

Regards

John

When you lift your foot off the accelerator nothing is powering the car. On the display you will see green arrows going from the wheels to the Battery "green for recovered energy that would normally be lost".

The electric motors turn into generators and put electricity back into the Battery. In doing this actually slows the car down in the same fashion as any other car slows when decelerating, but with other cars the engine is pushed round wasting energy. With Toyota/Lexus hybrids the engine stops completely.

The engine ware due to stop start is minimal due to the facts that, the engine is still hot, the oil does not have chance to drain down in a short period, and the engine does not start at low revs with little oil on the bearings. The engine is run up to 1500 rpm in milliseconds by one of the electric motors then fuel and ignition is applied making for a very smooth start.  

John

[NemesisUK]

So, basically, the electric motor spins up the ICE, increasing oil pressure, before the ignition starts. Yes, it is a very smooth start when it occurs as the car moving but a little less smooth when pulling away from standstill. The ICE start-up then feels ever so slightly more 'abrupt'

[Britprius]

This is due to the reversal of use of MG1 (motor generator one) while starting the engine it is being used as an electric motor, "tens of times more powerful than the normal starter motor" but immediately the engine starts it turns "or more accurately it is switched" into generator mode to supply more electricity to MG2 "the larger of the two motor generators in the transmission" along with the Battery to help drive the wheels.

Below is a link to a nomograph of how the system works. Scroll to near the bottom of the page and move the sliders to show how engine speed and the two MG's work together. Note MG1 will run in both directions depending on conditions. This is for a Prius, but the systems used in the Lexus are the same.

.http://eahart.com/prius/psd/ .

[NemesisUK]

The RC300h has only one electric traction motor?

[Britprius]

The above shows just how simple the hybrid transmission is. Never at any time is there an actual gear change even for reverse or neutral. The GS450H does have a  single gear change planetary set on one electric motor to reduce it's revs at speeds above 60mph.

All of the Toyota/Lexus hybrid transmissions have two MG's, but only MG2 is used for traction. MG1 is used for engine start and as a generator to supply the Battery or MG2 with power depending on conditions.

Four wheel drive systems such as in the RX use another motor built into the differential to drive the rear wheels. There being no mechanical link from the engine to the rear diff "no prop shaft". When braking the diff motor turns into a generator for regen braking on the rear wheels.

John

[Britprius]

I should have added to the above MG2 the traction motor becomes a generator every time you take your foot off the accelerator or put you foot on the brake. This is used to slow the car down by generating electricity and returning it to the Battery.

John

[NemesisUK]

"Where available, the transmission enhances driver engagement through two means.

Firstly, models with a sequential function built into the E-CVT system generate the feeling of manually changing gear ratios by providing a closer match between increases in engine and vehicle speed. This is also used to deliver stepped engine braking force under deceleration.

Secondly, models with a sport mode built into the E-CVT change the sensation of dynamic performance by increasing engine speed more rapidly during acceleration, as demonstrated in the diagram below."

http://blog.lexus.co.uk/perfect-partners-e-cvt-and-hybrid/

The above certainly add more driver 'involvement' should one wish it 

[Britprius]

Yes the system is very clever at fooling us into thinking we are using different gears when in fact it is a clever balancing act by the computer controlling the two MG's to give the impression of gear ratios. Even the traction control is performed by this operation.

John

[NemesisUK]

A little more info...

http://www.lexus-int.com/eco-thinking/power-of-h-engine.html

[RgrWynne]

Regarding engine wear, I think you only need look at the Prius, which is the global taxi of choice and achieve massive mileages.

[royoftherovers]

Yes Roger.You are correct as the mileages achieved are approaching the distance from Earth to the Moon and return (400,000 plus) !

 

Regards

John

[polk123]

On 12/5/2016 at 3:22 PM, Britprius said:

The engine ware due to stop start is minimal due to the facts that, the engine is still hot, the oil does not have chance to drain down in a short period, and the engine does not start at low revs with little oil on the bearings. 

John

I agree that it won't be a "cold" engine start, which will help matters. However, its the oil pressure which keeps the various components from rubbing against each other. Just having oil on the parts, without the oil pressure is will be fatal.

 

[polk123]

1 hour ago, RgrWynne said:

Regarding engine wear, I think you only need look at the Prius, which is the global taxi of choice and achieve massive mileages.

To be honest, don't see many (if any) Prius taxis around here. 

However, they may be popular in areas where emissions are more tightly controlled.

[NemesisUK]

21 minutes ago, polk123 said:

I agree that it won't be a "cold" engine start, which will help matters. However, its the oil pressure which keeps the various components from rubbing against each other. Just having oil on the parts, without the oil pressure is will be fatal.

 

Which is why I was asking about the possibility of an 'off-line' electric oil pump. Perhaps as the engine is spun up using the powerful traction motor there is significant oil pressure built up before any loads are applied to the ICE?

[Britprius]

19 hours ago, polk123 said:

I agree that it won't be a "cold" engine start, which will help matters. However, its the oil pressure which keeps the various components from rubbing against each other. Just having oil on the parts, without the oil pressure is will be fatal.

 

It is not the oil pressure that keeps components apart it is just the presents of oil that counts. In many small 4 stroke engines and all 2 stroke engines there is no oil pump. In the case of 2 stroke engine the oil is mixed with petrol.

John