TERS : Thermal Energy Recovery System

[saviour stivala]

If the regulations didn’t strictly define and regulate the differences between the throttle pedal function (travel defined as 0 – 100 travel) and the ICE throttles butterfly’s function (travel defined as 0 – 100 travel) said regulations would have been pushing forward to the teams a can of worms to choose from and play with. To start to understand the possibilities that would be open to the teams one should go back and research the 2011 EBD era and the abuse of the rules and polemics that resulted at that time. Something of which haven’t been talked about so far is, the regulations makes two exceptions to the above strict relation between throttle pedal and ICE throttle butterfly’s positions and functions, these to provide for the function of anti-stall prevention and pit-lane speed limiter function.

[henry]

If the regulations didn’t strictly define and regulate the differences between the throttle pedal function (travel defined as 0 – 100 travel) and the ICE throttles butterfly’s function (travel defined as 0 – 100 travel) said regulations would have been pushing forward to the teams a can of worms to choose from and play with. To start to understand the possibilities that would be open to the teams one should go back and research the 2011 EBD era and the abuse of the rules and polemics that resulted at that time. Something of which haven’t been talked about so far is, the regulations makes two exceptions to the above strict relation between throttle pedal and ICE throttle butterfly’s positions and functions, these to provide for the function of anti-stall prevention and pit-lane speed limiter function.

In the regulations what you refer to as the throttle pedal is called the accelerator pedal.

There are just two mentions of the word throttle.

5.6.5 A number of power unit protections are available in the ECU.
A minimum of nine seconds hold time should be configured for the power unit protections enabled during qualifying and race. The configuration of the air tray fire detection and throttle failsafe are exceptionally unrestricted in order to allow each team to achieve the best level of safety.

4
PU Engine air inlet system from plenum entry to cylinder head (e.g. plenum, trumpets, throttles)

The second is from the appendix and is there to identify parts that may be changed without affecting the count of power unit components used.

I can find no mention of the pit lane speed limiter. Maybe that’s a driver aid that is not explicitly permitted but as a safety item is not disallowed.

I can understand your frustration. From the inception of these regulations the marketing position has been that these Power Units are exceptionally efficient and they do so by reusing energy that in previous eras was wasted. In this marketing view the MGU-K is there to recover energy that would otherwise be lost in braking and the MGU-H to recover that which be lost in the exhaust.

Anything that complicates that message is ignored. The stellar improvement in combustion efficiency never gets a mention, because the target audience have no concept of thermal efficiency. Likewise any use of the MGU-K which doesn’t involve braking is ignored.

The teams have a different view of efficiency, it’s about minimising race time and/or qualifying lap time. The regulations don’t restrict some other uses of the MGU-K, to gather energy by burning fuel.so they use them. This is very like the EBD situation you mention, burn more fuel to reduce lap time. In that case they cracked down on it. So why haven’t they done so this time? I suggest it is because they consider there marketing message safe, outside of forums such as this the use of the MGU-K to charge the ES by burning fuel is never mentioned.

The control of this message is strong. I have just started to read the PhD paper @subcritical71 linked to. The author describes a model of operation that exactly matches the marketing article you referred to earlier even though he also shows in a diagram the PU output as a mix of MGU-K and ICE.

This marketing versus reality is common in F1. They advertise the WDC as the best driver, when we all know it’s the better driver in the best car .

[Tommy Cookers]

......The stellar improvement in combustion efficiency never gets a mention, because the target audience have no concept of thermal efficiency.

agreeing with the previous post .... except that ....

the combustion efficiency is driven by the % of fuel burned (in-cylinder or in-PU) - and has changed little

it's the indicated thermal efficiency (the % of heat released that has turned into work) that has had a stellar improvement
largely because heat losses to cooling and to exhaust are unusually low due to heat dilution from the extreme leaning

[Tzk]

If the regulations didn’t strictly define and regulate the differences between the throttle pedal function (travel defined as 0 – 100 travel) and the ICE throttles butterfly’s function (travel defined as 0 – 100 travel) said regulations would have been pushing forward to the teams a can of worms to choose from and play with.

Yes, and this is exactly what happened. The regulations define a strict connection from the drivers foot (accelerator pedal) to the power/torque output of the power unit. As you mentioned this basically maps accelerator pedal position 0-100 to PU power output 0 - 100. Note that i wrote PU and not ICE power output. There is no direct mapping of the driver foot to the throttle body position. And yes, this opens a whole can of worms regarding the engine mapping and possibilities to harvest/deploy for the engineers to play with. This is why getting the PU mapping and harvest strategy right is so important for the teams.

They even have a further exception of this rule by stating that the power unit control electronics may define for itself what (and how much) "full power" is. This opens up the possibility to harvest energy from the PU at the end of the straights while the driver is still pushing the accelerator paddle to max. position. If you watch some onboard footage from the latest race, you'll notice that some cars actually become slower way before the braking zone. This happens because a) they run out of electrical energy to feed the mgu-k and b) because they begin to harvest from either mgu-h or mgu-k long before the driver begins to brake for the corner. When this happens, the brake light on the car begins to flash to indicate this.

[gruntguru]

If the regulations didn’t strictly define and regulate the differences between the throttle pedal function (travel defined as 0 – 100 travel) and the ICE throttles butterfly’s function (travel defined as 0 – 100 travel) said regulations would have been pushing forward to the teams a can of worms to choose from and play with. . . .

"Strictly defining" the relationship between accelerator pedal and engine throttles would achieve nothing. As previously stated the engine output can easily be controlled without moving the throttles. As an extreme example, the engine could be operated with throttles wide open and output reduced to 10 or 20% of full load by skip-firing, under-fuelling, boost reduction via MGUH braking etc, etc.

In summary - there is NO RULE governing the opening of the engine throttles. I am not even sure the rules dictate there must be a throttle fitted to the engine.

[Tzk]

Interesting thought. Modern street diesel engines (tdi) regulate the power output with boost levels and the injected amount of fuel.

Afaik bmw even had a variable timing and valve lift (which both is banned in f1) in a gasoline engine and could use it with almost zero throttle usage.

[roon]

The Valvetronic system is a BMW variable valve lift system[1] which, in combination with variable valve timing, allows infinite adjustment of the intake valve timing and duration.[2] The system claims to improve fuel economy and emissions, and negates the need for a throttle body in regular use.

https://en.wikipedia.org/wiki/Valvetronic

[FPV GTHO]

If the regulations didn’t strictly define and regulate the differences between the throttle pedal function (travel defined as 0 – 100 travel) and the ICE throttles butterfly’s function (travel defined as 0 – 100 travel) said regulations would have been pushing forward to the teams a can of worms to choose from and play with. To start to understand the possibilities that would be open to the teams one should go back and research the 2011 EBD era and the abuse of the rules and polemics that resulted at that time. Something of which haven’t been talked about so far is, the regulations makes two exceptions to the above strict relation between throttle pedal and ICE throttle butterfly’s positions and functions, these to provide for the function of anti-stall prevention and pit-lane speed limiter function.

In the regulations what you refer to as the throttle pedal is called the accelerator pedal.

There are just two mentions of the word throttle.

5.6.5 A number of power unit protections are available in the ECU.
A minimum of nine seconds hold time should be configured for the power unit protections enabled during qualifying and race. The configuration of the air tray fire detection and throttle failsafe are exceptionally unrestricted in order to allow each team to achieve the best level of safety.

4
PU Engine air inlet system from plenum entry to cylinder head (e.g. plenum, trumpets, throttles)

The second is from the appendix and is there to identify parts that may be changed without affecting the count of power unit components used.

I can find no mention of the pit lane speed limiter. Maybe that’s a driver aid that is not explicitly permitted but as a safety item is not disallowed.

I can understand your frustration. From the inception of these regulations the marketing position has been that these Power Units are exceptionally efficient and they do so by reusing energy that in previous eras was wasted. In this marketing view the MGU-K is there to recover energy that would otherwise be lost in braking and the MGU-H to recover that which be lost in the exhaust.

Anything that complicates that message is ignored. The stellar improvement in combustion efficiency never gets a mention, because the target audience have no concept of thermal efficiency. Likewise any use of the MGU-K which doesn’t involve braking is ignored.

The teams have a different view of efficiency, it’s about minimising race time and/or qualifying lap time. The regulations don’t restrict some other uses of the MGU-K, to gather energy by burning fuel.so they use them. This is very like the EBD situation you mention, burn more fuel to reduce lap time. In that case they cracked down on it. So why haven’t they done so this time? I suggest it is because they consider there marketing message safe, outside of forums such as this the use of the MGU-K to charge the ES by burning fuel is never mentioned.

The control of this message is strong. I have just started to read the PhD paper @subcritical71 linked to. The author describes a model of operation that exactly matches the marketing article you referred to earlier even though he also shows in a diagram the PU output as a mix of MGU-K and ICE.

This marketing versus reality is common in F1. They advertise the WDC as the best driver, when we all know it’s the better driver in the best car .

I think the FIA knew full well they had vague areas and loopholes in the rules, the biggest perhaps being unlimited energy transfer between the H and K. They intended the ERS side of the PU to be the main development area.

[roon]

One of the published challenges for the AMG One road car was dropping the idle speed from ~5k to 1.5k for emissions (and NVH as well, I'd guess) reduction. I've seen no traditional throttles in published photos of the Merc F1 turbo-hybrid engine nor it's road car derivative. They have variable stator vanes before the compressor with an annular control ring--perhaps this can function as a throttle.

Renault have used ITBs in the past. I surmise from photos which show a bearing intersecting the center of an intake runner. Each bank looks linked i.e. not independently controlled. Note the shared linkage, second photo below--gold colored bellcrank. These throttles are downstream from the VIR mechanisms and just ahead of the intake valves.

[saviour stivala]

A very interesting discussion (would like to extend thanks for as offered to ‘gruntguru” to all), has now got to a point were a lot of chaff is being added instead of it being separated (variable valve timing, variable valve lift, throttle-less intakes and much more, to very near the ‘ECU/CONTROL ELECTRONOCS’ driving the car as regards driver throttle/accelerator pedal position demand. Would like to remind all, if permitted, of the wise words reminder of 5/6 days ago on this thread. (whereas this topic is quite interesting ------------“debate” obviously some will interpret the rules in a manner that suits them, but that does not mean that they are always correct) obviously the above includes me and my opinion/interpretations of the rules. Who after all is talking about these subject rules without not expressing his personal interpretations of said rules?. Having said all that, although there must sure be parts were I did not express myself in a correct way, when expressing my opinion/s, I stand with my personal opinion as expressed re ‘K’ harvesting and driver throttle/accelerator pedal position requests and control as to what goes to the driven wheels.

[henry]

......The stellar improvement in combustion efficiency never gets a mention, because the target audience have no concept of thermal efficiency.

agreeing with the previous post .... except that ....

the combustion efficiency is driven by the % of fuel burned (in-cylinder or in-PU) - and has changed little

it's the indicated thermal efficiency (the % of heat released that has turned into work) that has had a stellar improvement
largely because heat losses to cooling and to exhaust are unusually low due to heat dilution from the extreme leaning

Agreed. The overall efficiency of these power units is as you say. But in the context of my argument I did not intend to include the MGU-H contribution. I was clumsily trying to indicate that the crank power from the ICE has gone up considerably from around 30% to over 40% of fuel energy content.

If there is the same energy release from the fuel would it not be that heat dilution means that more of the energy would go through the exhaust, at lower temperature, and the contribution to the PU power is via the Turbine >MGU-H > MGU-K route which only returns about 6% of the fuel energy. Mercedes claim 50% when in this mode. (On the Dyno)

So if the %age of fuel burned hasn’t changed what is it that has increased the crank ITE by 14 %age points? Crank work from the compressor, more complete combustion....

[Tommy Cookers]

I was clumsily trying to indicate that the crank power from the ICE has gone up considerably from around 30% to over 40% of fuel energy content. .....
So if the %age of fuel burned hasn’t changed what is it that has increased the crank ITE by 14 %age points? Crank work from the compressor, more complete combustion....

imo
the % fuel burned (in-cylinder anyway) hasn't changed
conventional engines were/are designed to a leaning limit that gives about 95% combustion efficiency
ie even these F1 engines have their leaning limited this way (though their leaning is significantly more than conventional)
below 95% combustion efficiency there is a sharp increase in combustion intermittency

these F1 engines (designed for running unconventionally lean) dilute the in-cylinder heat (far more than conventional lean)
ie the mean in-cylinder temperature is lower
so the heat taken by coolant is disproportionately lower
(generally engines can still work even with heat rate lowered enough for no cooling to be needed)
the reduction in cylinder heat taken by coolant is an increase in available heat and so in heat converted to work
that's a big source of the great increase in the crank ITE and BTE
(the very high geometric compression/expansion ratio and reduction/elimination of CO2/CO dissociation also help)

btw
what's the mystery with the rules on the accelerator displacement/torque output relationship ??
technology used 25 years ago with the mapping limited to the specified 2-d imposed c.2000 ?
(a throttle map + a torque map = an accelerator-to-torque map type as currently)
the 2-d map now seems to mandate constant power ie reducing torque with rpm rise - but this was available in NA F1
but weren't EBD restrictions implemented primarily by supplementary rules on undue changes in ignition timing etc ?

[gruntguru]

The improvement in ITE has a number of sources IMO.
- I believe there is a worthwhile improvement in % fuel burned. Most obviously, previous engines were running on the rich side of stoichiometric at full load and every 1% decrease in lambda is at least 1% more fuel that cannot be burned.
- Agree with Tommy on ultra lean -> high dilution -> low heat rejection to the cylinder.
- Stratified charge to isolate the hottest gases from the cylinder walls)
- Rapid combustion to concentrate pressure rise near TDC. The result is more expansion work on the piston and lower gas temperature at EVO -> lower exhaust temperature. (The biggest challenge is achieving this at very lean AFR - overcome by the advent of TJI)
- Recovery of exhaust heat - not only to the MGUH but also to the compressor which then adds work to the pistons during the intake stroke.
- Operation closer to peak thermal efficiency at part load conditions. There are a number of techniques used including cylinder skipping, Ultra lean burn unthrottled, MGUK braking to operate the ICE at a higher load than required while storing surplus energy.

[saviour stivala]

5.5.3. The MGU-K must be solely and permanently mechanically linked to the powertrain before the main clutch. This mechanical link must be of a fixed speed ratio to the engine crankshaft.
The rotational speed of the MGU-K may not exceed 50k rpm.
The max torque of the MGU-K may not exceed 200Nm. (The MGU-K being geared to the ICE crankshaft at a fixed ratio of 3.333 both ways. when deploying or harvesting. will be contributing a max electrical output of 200Nm to the ICE crankshaft, when the ICE crankshaft is rotating at a max power speed of 10500 RPM. This combined mix of electrical and ICE power/torque or any other contributed mix of power/torque as per the driver selected from on the steering wheel combination of deploy/harvest mapping, will go to the driven wheels as per the driver's throttle/accelerator pedal position request. the driver throttle/accelerator pedal movement (0 - to - 100 movement) controls the power unit RPM trough the ICE throttle/s.
The torque will be referenced to the crankshaft speed and the fixed efficiency correction defined in article 5.2.2 will be used to monitor the MGU-K torque.
5.2.2. Electric DC measurements will be used to verify that the energy and power requirements are being respected.
A fixed efficiency correction of 0.95 will be used to monitor the max MGU-K power.
(All the energy to the ‘K’ comes from a single inverter. So DC – in to that inverter is measured”. “ ‘H’ – to - ‘k’, ‘k’ – to – ‘H’ --- AC - to – AC. The frequency of AC from ‘H’ is different to the frequency from ‘K’ so it needs to run through the inverter. In short, not possible for direct connection ‘H’ – to – ‘K’ ----- ‘K’ – to – ‘H’).
(The inverter “V3F DRIVE” controls the ‘K’ on requirements of the throttle).
All the recovered power released to the wheels must be through the single MGU-K.
The energy recovery system is highly responsive, with energy flows in and out of the battery taking place in response to driver throttle and braking inputs.

[hollus]

Some sections are 2015 regs. Do they still say the same in 2019?
Other sections are personsl interpretation. It would have be most helpful to specify which parts are regulation and which are interpretation.
Or am I missing a source?