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#1 malbear

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Posted 10 November 2013 - 07:31

I am wondering if any F1 engines use electric drive water pumps or electric drive oil pressure and extraction pumps.

the theoretical advantage would be that good flow and pressure could be available at idle and not so much energy or parasitic losses at high revs .



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#2 Lee Nicolle

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Posted 10 November 2013 - 22:08

While F1 is not 'real' electric waterpumps are drag racing stuff. The coolant travels at one speed. I have [bad] experiences with them on speedway cars. The car constantly got hot, eventually I talked the owner to go back to the proven mechanical pump and no more overheating. Not only did he finish a 20 lap feature he won it! And it stopped flicking the alternator belt too. I don't know if the flow was too fast or too slow but it had no facility to vary flow.
An electric scavenge pump/s may be practical, the pressure pump would be too unreliable as it would drag a lot of current. Reputedly a Weaver bros pump uses 15hp to maintain 55lb on a Chev. More pressure consumes more power and I suspect an 18000rpm engine would need more pressure and volume.

#3 Canuck

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Posted 10 November 2013 - 23:52

I'm curious if that's true (pressure and volume needs increase with engine speed)?  I haven't read anything one way or the other beyond there being an optimum.



#4 bigleagueslider

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Posted 11 November 2013 - 03:36

I'm curious if that's true (pressure and volume needs increase with engine speed)?  I haven't read anything one way or the other beyond there being an optimum.

With lube oil and liquid coolant, the most relevant relationship is oil/coolant mass flow and indicated engine power.  Both oil and coolant flows are determined by heat transfer requirements. So we care more about the fluid mass flow, specific heat and delta T than we do about the volume flow rate or circuit pressure. But practically, since both fluids are liquids being used within a fairly narrow range of temperatures we can use volume flow to describe each system's operating characteristics.

 

Using an electric motor to power a variable flow oil/coolant pump in response to engine output would greatly improve fuel economy at part throttle operation, and this is being used on a few production automotive engines.  But since F1 engines are mostly operated at WOT conditions, they would not benefit so much from this approach.  With F1 cars, we must also consider the added weight and volume of the electric motor, batteries, wiring and power electronics required for such a system. 

 

Rather than an electric drive for F1 oil/coolant pumps, I would suggest changing the rules to allow variable geometry radiator duct inlets/outlets.  This would give far more "bang-for-the-buck" in terms of performance than electric drives for oil/coolant pumps, and would probably be much less complicated.  This basic concept was commonly used on most piston engine aircraft during the mid 20th century.



#5 Wuzak

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Posted 11 November 2013 - 04:11

While F1 is not 'real' electric waterpumps are drag racing stuff. The coolant travels at one speed. I have [bad] experiences with them on speedway cars. The car constantly got hot, eventually I talked the owner to go back to the proven mechanical pump and no more overheating. Not only did he finish a 20 lap feature he won it! And it stopped flicking the alternator belt too. I don't know if the flow was too fast or too slow but it had no facility to vary flow.
An electric scavenge pump/s may be practical, the pressure pump would be too unreliable as it would drag a lot of current. Reputedly a Weaver bros pump uses 15hp to maintain 55lb on a Chev. More pressure consumes more power and I suspect an 18000rpm engine would need more pressure and volume.

Surely an electric water pump can be set up with a feedback loop such that the coolant flow is controlled by the cooling requirements, not the engine speed - as in a mechanical pump?



#6 Greg Locock

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Posted 11 November 2013 - 05:18

Of course you could. many years ago we looked at using PWM 12V motors on the cooling fans for Falcon. The PWM duty cycle was set by the ECT sensor. It was absolutely brilliant, and amazing how much of the time just the gentlest waft of air was all that was necessary.

 

My job was to define which fan speeds were forbidden as they excited resonances. Sadly management zapped that system and instead we ended up with 2 speed fans, but I still used the PWM fan data to set the intermediate speed.

 

The one that always puzzled me was Toyota's oil powered cooling fan.



#7 ray b

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Posted 11 November 2013 - 05:40

with the return of turbo's next year

could  exhaust driven accessory's be used ?

by oil air or electrical power transfer ?   



#8 Greg Locock

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Posted 11 November 2013 - 09:20

I don't know if it is F1 legal but 25 years ago Lotus were working on an alternator that ran off the turbo.



#9 Wuzak

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Posted 11 November 2013 - 10:36

I don't know if it is F1 legal but 25 years ago Lotus were working on an alternator that ran off the turbo.


That would be the original MGUH then. Obviously not designed to extract as much power as next year's units, but the same principle.

#10 John Brundage

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Posted 11 November 2013 - 13:10

The one that always puzzled me was Toyota's oil powered cooling fan.

  Haven't seen Toyota's but Detroit Diesel used a Torus fan drive which was driven by engine oil pressure. The oil flow was controlled by a temperature valve, vernatherm if I recall correctly. I haven't seen or worked on one of those for almost 20 years.



#11 Magoo

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Posted 11 November 2013 - 13:32

Yes indeed, many big road diesels have used hydraulic fan drives -- Detroit, Cummins, Cat, etc. 

 

 

Ford used some hydraulic cooling fans -- Lincoln LS and most recent Thunderbird, 3.9L V8. Hydraulic with electronic control via PWM. This engine also used an auxiliary electric water pump, I seem to recall. 



#12 mrdave

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Posted 11 November 2013 - 13:37

I don't know if it is F1 legal but 25 years ago Lotus were working on an alternator that ran off the turbo.

Semi on topic, all the curent F1 engines are not allowed to be modified since the spec was frozen in 2007. However what is an engine? (in the FIA's eyes). What im leading to is, could development of the above happen?



#13 indigoid

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Posted 11 November 2013 - 14:15

The one that always puzzled me was Toyota's oil powered cooling fan.

 

Interesting, do you remember what model it was on?



#14 Greg Locock

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Posted 11 November 2013 - 21:27

Camry, but I can't remeber if it was the I4 or V6. Say about year 2000



#15 bigleagueslider

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Posted 13 November 2013 - 03:42

With the use of battery-electric KERS in F1, there is no logical reason for prohibiting electrically driven engine auxiliaries.  Production autos (espicially EVs and hybrids) now use electric motors to drive all sorts of auxiliary systems, such as power steering, power brakes, A/C compressors, radiator fans, engine throttles, fuel pumps, coolant pumps, etc.  So why shouldn't F1 do likewise?



#16 Lee Nicolle

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Posted 13 November 2013 - 09:04

Camry, but I can't remeber if it was the I4 or V6. Say about year 2000

V6 and it was less than satisfactory. like most things on a V6 Camry.

#17 Lee Nicolle

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Posted 13 November 2013 - 09:07

Surely an electric water pump can be set up with a feedback loop such that the coolant flow is controlled by the cooling requirements, not the engine speed - as in a mechanical pump?

Sure it can be. But really why. The belt driven mechanical pump is simple and reliable. Unlike a stack of electronics which will end up heavier anyway. And the alternator works harder so that drags most of any power savings.
Look at me,, I invented something power saving, it just needs more power to drive it!

You can drive things off the turbo but again not practical.So much heat! Most alternators are driven off the gearbox still as far as I know. Simple and reliable.

Edited by Lee Nicolle, 13 November 2013 - 09:13.


#18 Wuzak

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Posted 13 November 2013 - 21:57

Sure it can be. But really why.


Surely it would enable better temperature control of the cooling system?


The belt driven mechanical pump is simple and reliable. Unlike a stack of electronics which will end up heavier anyway. And the alternator works harder so that drags most of any power savings.


I would think better temperature control is the more useful gain.

The electric drive would not be taking any power when it is not required. And at high rpm, when the mechanical pump is taking its maximum drive power, the electric version would, I imagine, use much less power.


Look at me,, I invented something power saving, it just needs more power to drive it!


I find it hard to believe that the electric drive would require more power. At worst it would require the same power.

#19 MatsNorway

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Posted 13 November 2013 - 23:23

I drove past a wheel loader on the road to work here the other day and it had a hydraulic motor to drive the cooling fan. I found that odd given a electric motor would last longer.



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#20 indigoid

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Posted 14 November 2013 - 00:01

Surely it would enable better temperature control of the cooling system?

 

Could you not do this now with a clutched pulley? Like my Toyotas all had on the AC compressor



#21 Catalina Park

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Posted 14 November 2013 - 02:37

If you want better temperature control of the cooling system I suppose you could fit a thermostat. 



#22 Lee Nicolle

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Posted 14 November 2013 - 06:44

If you want better temperature control of the cooling system

 I suppose you could fit a thermostat.
With a constant speed pump the t stat wont control the flow enough.
I had a call this week from a radiator customer whose hot Monaro always got hot on a drive.220F+ F all the time. I sold him a new radiator and told him the waterpump was the fault. He eventally listened after putting on extra fans, shrouds etc and replaced the factory water pump and presto he did a 100k trip at 170F. Which is now way too cold. But he is happy and likes it cold though I told him he is doing more damage now cold than it was hot.

#23 Lee Nicolle

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Posted 14 November 2013 - 07:08

Surely it would enable better temperature control of the cooling system?



I would think better temperature control is the more useful gain.

The electric drive would not be taking any power when it is not required. And at high rpm, when the mechanical pump is taking its maximum drive power, the electric version would, I imagine, use much less power.

Think man,, you cannot stop the water from flowing. most modern vehicles yet alone race engines would never survive on thermo syphon.They would fry them selves in a few minutes. Break a fan belt at 110k and the engine is boiling by the time you stop.
Water has to flow at all times, cold or hot. Most road car systems turn the pump too fast for sustained high rpm use. eg 150% of crank speed, I have found normally crank speed is the best for most race applications using up to 7500 rpm. 4,6,and 8 cyl engines.
In Nascar they go as slow as 75% of crank speed but are right on the edge of safety there. I tried 80%, ok on a cold day in an open environment like Philip Island but at the GP racing in a concrete tunnel crank speed was still borderline on a hot day. The slower the pump rpm the less power consumed. But go too slow and the engine cooks, conversely go too fast and it still does as the water races through the radiator and does not get a chance to cool.
The above is motorsport prep 101. Just basic simple commonsense. The same goes with alternators, they seize, flick belts, centrifuge the fan out if you turn them too hard. Actually the first thing is remove the fan, unecesary on a race engine and then slow it down as slow as it will charge adequately. Personally I hate them, have had them short out, break the brackets, seize and for my short events very happily survive without one.
For power steering to me hydrauliuc is best, simple and reliable. Electric PS has little feel and an electric motor as a servo is far less user friendly. And to me Power steer is for the towcar!! IF you use it then you have to slow down pumps, adjust pressures and then if you get the car very loose and near stall the engine you have no assistance. Done this both in road racing and speedway where I hated the lack of sensitivity of the modified road car power steering. More mental effort to do the job.
Interestingly most speedway [ Sprintcar, speedcar]steering boxes are only road car gears and servos in an special alloy case. Though some do have some special gear ratios. And ofcourse the PS consumes more power! And is extra weight in the car



I find it hard to believe that the electric drive would require more power. At worst it would require the same power.



#24 gruntguru

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Posted 14 November 2013 - 08:03

Yes water has to flow all the time but the rate it needs to flow and the power consumed to achieve that flow rate are achieved rather poorly by the traditional system of pump-geared-to-engine-speed plus thermostat. A variable speed electric water pump would do the job more accurately and efficiently. Same for oil pumps. Having said that, it is hard to beat the simplicity and reliability of the mechanically driven systems.



#25 Lee Nicolle

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Posted 14 November 2013 - 09:32

Yes water has to flow all the time but the rate it needs to flow and the power consumed to achieve that flow rate are achieved rather poorly by the traditional system of pump-geared-to-engine-speed plus thermostat. A variable speed electric water pump would do the job more accurately and efficiently. Same for oil pumps. Having said that, it is hard to beat the simplicity and reliability of the mechanically driven systems.

I very much doubt 'hi tech' would do a better job. BUT it would cost a lot more to implement than the simplicity of mechanical systems. As I said before 'Look I have reinvented the wheel'
On most popular models a waterpump and thermostat costs about a $100 and lasts generally about 10 years if proper coolants are used. A hi tech electric waterpump and control systems is going to cost a LOT more.

As a matter of interest what do they currently use on F1 cars? The lower level cars all use production based units. F1 is seldom real or commonsense. Though sometimes that is the object ofcourse.

#26 gruntguru

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Posted 14 November 2013 - 10:25

I said "more accurately and efficiently" - "A better job" has a different meaning.

 

Yes - F1 cars cost a lot more than ordinary cars. A mechanical pump for an F1 car would cost more than $100 I suspect.

 

There is no question that temperature is controlled more accurately. There is also no question that less energy is consumed driving an electronically controlled water pump with no thermostat. (I have seen one in action by the way.) Same applies to the electric oil pump with no relief valve. At high revs a mechanical oil pump wastes a lot of energy - pumping oil through the relief valve.



#27 Wuzak

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Posted 15 November 2013 - 01:19

As a matter of interest what do they currently use on F1 cars? The lower level cars all use production based units. F1 is seldom real or commonsense. Though sometimes that is the object ofcourse.

 

I'm not sure what they use in F1, but it may be restricted in the regulations (with regards to extra actuators/motors).



#28 J. Edlund

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Posted 15 November 2013 - 19:37

I am wondering if any F1 engines use electric drive water pumps or electric drive oil pressure and extraction pumps.

the theoretical advantage would be that good flow and pressure could be available at idle and not so much energy or parasitic losses at high revs .

 

To my knowledge, no F1 engine is using electric driven or variable displacement pumps. The gains at high speed and load would be small compared to a properly designed and sized mechanical pump. The 700 or so watts the permanent magnet alternators can deliver wouldn't last long if we're going to use electric pumps, certainly with regards to the oil pumps which needs a few kW at speed. Variable displacement is probably a more realistic approach at least for the oil pumps, but such a pump will end up heavier and bulkier than a conventional pump.

 

I think there are bigger gains to be had elsewhere. For instance, it is possible to reduce power consumption of the oil pump by reducing the oil flow and pressure requirement of the engine (smaller bearing clearances, better oil supply to the crankpins). This will also reduce the amount of oil in the crankcase, which will have a positive impact on churning losses which is probably a greater concern at F1 speeds than pump losses. It is also possible to reduce the power usage of the oil pump by running a larger displacement pump slower, better oil quality (less foaming) is an added bonus.

 

I'm curious if that's true (pressure and volume needs increase with engine speed)?  I haven't read anything one way or the other beyond there being an optimum.

 

If we talk about oil, the flow and pressure need increase slightly with engine speed. But modern engines can also use oil for hydraulic purposes, like controlling cam phasing which will complicate matters.

 

For a production engine it is usually hot idling that is limits pump size, as flow demand will increase with increased oil temperature while the flow of the pump is more or less linear with pump speed.

 

I drove past a wheel loader on the road to work here the other day and it had a hydraulic motor to drive the cooling fan. I found that odd given a electric motor would last longer.

 

Not very odd at all. All construction machinery like wheel loaders are equipped with powerful hydraulic pumps but not an alternator powerful enough to power a suitable fan. Some machines, like excavators even use hydraulic motors for propulsion, so life expectancy of the fan motor isn't really a concern. 

 

As a matter of interest what do they currently use on F1 cars? The lower level cars all use production based units. F1 is seldom real or commonsense. Though sometimes that is the object ofcourse.

 

They use bespoke centrifugal coolant pumps. Oil pumps consist of a gear or gerotor pressure section with relief valve and gerotor or roots scavenge pumps with a centrifugal air oil separator. There is typically one or two scavenge pumps per crankcase and separate pumps for the heads and geartrain.

 

The coolant pumps (typically one or two) probably have simpler shaft seals than production units, but the pump itself is designed for better performance and less for low production costs (you won't find any stamped steel rotors like in mass production units).



#29 ray b

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Posted 15 November 2013 - 21:02

To my knowledge, no F1 engine is using electric driven or variable displacement pumps. The gains at high speed and load would be small compared to a properly designed and sized mechanical pump. The 700 or so watts the permanent magnet alternators can deliver wouldn't last long if we're going to use electric pumps, certainly with regards to the oil pumps which needs a few kW at speed. Variable displacement is probably a more realistic approach at least for the oil pumps, but such a pump will end up heavier and bulkier than a conventional pump.

 

''permanent magnet alternators''????

is not that called a generator and dropped by road cars in the 60's

in favor of a wound field coil alternator  outputting A/C converted to D/C

 

i SUSPECT THERE ARE A FEW EL PUMPS DOING TRANSFERS AND FUEL SUPPLY TOO



#30 Lee Nicolle

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Posted 16 November 2013 - 07:40

To my knowledge, no F1 engine is using electric driven or variable displacement pumps. The gains at high speed and load would be small compared to a properly designed and sized mechanical pump. The 700 or so watts the permanent magnet alternators can deliver wouldn't last long if we're going to use electric pumps, certainly with regards to the oil pumps which needs a few kW at speed. Variable displacement is probably a more realistic approach at least for the oil pumps, but such a pump will end up heavier and bulkier than a conventional pump.
 
I think there are bigger gains to be had elsewhere. For instance, it is possible to reduce power consumption of the oil pump by reducing the oil flow and pressure requirement of the engine (smaller bearing clearances, better oil supply to the crankpins). This will also reduce the amount of oil in the crankcase, which will have a positive impact on churning losses which is probably a greater concern at F1 speeds than pump losses. It is also possible to reduce the power usage of the oil pump by running a larger displacement pump slower, better oil quality (less foaming) is an added bonus.
 
 
If we talk about oil, the flow and pressure need increase slightly with engine speed. But modern engines can also use oil for hydraulic purposes, like controlling cam phasing which will complicate matters.
 
For a production engine it is usually hot idling that is limits pump size, as flow demand will increase with increased oil temperature while the flow of the pump is more or less linear with pump speed.
 
 
Not very odd at all. All construction machinery like wheel loaders are equipped with powerful hydraulic pumps but not an alternator powerful enough to power a suitable fan. Some machines, like excavators even use hydraulic motors for propulsion, so life expectancy of the fan motor isn't really a concern. 
 
 
They use bespoke centrifugal coolant pumps. Oil pumps consist of a gear or gerotor pressure section with relief valve and gerotor or roots scavenge pumps with a centrifugal air oil separator. There is typically one or two scavenge pumps per crankcase and separate pumps for the heads and geartrain.
 
The coolant pumps (typically one or two) probably have simpler shaft seals than production units, but the pump itself is designed for better performance and less for low production costs (you won't find any stamped steel rotors like in mass production units).

That is something. Tin impellor pumps are bad news as they centrifuge and seize at high RPM. The impellors can also fall off and I have even seen one lost half the impellors through corrosion. Cast iron impellor is far more accurate, less cavitation and aeration of the coolant. Most OEM pumps are made like that. Though F1 probably uses some exotic metal because they can!

Belt driven pumps are more reliable than direct driven. eg off the cam or crank. And put less harmonics back into the engine. Modern Sprintcars are 'ouch'. Most drive the water pump off the crank, the oilpumps, powersteering and hydraulic wing pumps all off the cam, both ends! Breaking steel cams is not unusual. Though belt driven pumps on dirt can be a drama too as the mud goes through the belt and breaks or flicks the belt off. V Belt or tooth belt. Whatever way maintenance and inspection is a premium.

Edited by Lee Nicolle, 16 November 2013 - 07:41.


#31 bigleagueslider

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Posted 17 November 2013 - 02:30

With high rpm F1 engines, losses due to crankcase oil windage can be substantial.  So F1 engines use crankcase oil scavenge pump systems that have a flow volume rate several times that of the pressure pump.  The oil in the engine crankcase is mostly in the form of tiny droplets within a turbulent air/oil mist.  The scavenge pumps are oversized so that they can efficiently evacuate this air/oil mixture from the crankcase, and prevent it from creating excessive windage losses as the crankshaft/rods pass thru it at high velocity.  These high-volume scavenge pump systems can consume quite a bit of power.

 

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#32 Lee Nicolle

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Posted 17 November 2013 - 08:16

As does any serious race engine. There is more to engine power and reliability in a good sump system than many other fancier things.
A 3 or 4 stage Weaver, Moroso etc dry sump pump does the same job on more generic engines. Not as fancy and nowhere near as expensive either.
Making an electric one would really be a waste of time and effort. Even this hi tech system is still simple in comparison.

#33 gruntguru

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Posted 17 November 2013 - 09:39

With high rpm F1 engines, losses due to crankcase oil windage can be substantial.  So F1 engines use crankcase oil scavenge pump systems that have a flow volume rate several times that of the pressure pump.  The oil in the engine crankcase is mostly in the form of tiny droplets within a turbulent air/oil mist.  The scavenge pumps are oversized so that they can efficiently evacuate this air/oil mixture from the crankcase, and prevent it from creating excessive windage losses as the crankshaft/rods pass thru it at high velocity.

 

Hate to be picky (not really) but the primary reason for oversizing the scavenge pumps is because the volume of air/oil they pump is far greater than the liquid oil pumped by the pressure pump. True, there is a secondary benefit in reducing crankcase pressure but not all dry sump systems actually do that.


Edited by gruntguru, 17 November 2013 - 09:40.


#34 desmo

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Posted 17 November 2013 - 13:47

Two ways of saying essentially the same thing?



#35 Canuck

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Posted 17 November 2013 - 15:11

If you had a negative crankcase pressure, ignoring the oil control discussion, don't you end up in a zero-sum game with respect to crank train motion? I've heard or read that a negative pressure scenario reduces pumping losses as the pistons aren't pushing air out of the way on the downstroke. If this is true, aren't they effectively pulling vacuum against the pump on the upstroke?

#36 desmo

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Posted 17 November 2013 - 20:12

We need a trace of crankcase pressure vs. crank angle in an aggressively scavanged high rpm engine to see this clearly I think.  With paired cylinders using a common case segment wouldn't the volume below the piston change hugely each rotation?



#37 MatsNorway

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Posted 17 November 2013 - 20:42

Good points. The lesser pressure the less mass of air gets pushed around btw.

 

With desmos point one have the potential to assist the pump in cycles. Is there pumps that would allow usage of the cyclic pressure peaks?



#38 gruntguru

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Posted 17 November 2013 - 22:57

Two ways of saying essentially the same thing?

 

No there are two issues at play.

1. Because the sump is "dry", one or more of the scavenge pickups will always be drawing air. Because of this the scavenge pumps must be sized to handle the total volume of air plus oil which is far greater than the volume of circulating oil alone.

2. Reducing air pressure in the crankcase reduces frictional losses. (it also has the benefit of maintaing a more consistent piston ring contact with the cylinder plus reducing oil consumption by means of a more favourable pressure differential at all sealing points - rings, seals, gaskets etc)

 

If you had a negative crankcase pressure, ignoring the oil control discussion, don't you end up in a zero-sum game with respect to crank train motion? I've heard or read that a negative pressure scenario reduces pumping losses as the pistons aren't pushing air out of the way on the downstroke. If this is true, aren't they effectively pulling vacuum against the pump on the upstroke?

1. Negative pressure on the piston underside is a zero sum game - what you gain on the downstroke is lost on the upstroke.

2. Work done by a crankcase vacuum pump is the product of pressure differential (difference to atm) and air leakage rate into the crankcase. If the crankcase is well sealed (blow-by is usually the largest leak) the pump power is low.

3. The power advantage comes from reducing windage (moving parts stirring the air and oil spray in the crankcase).


Edited by gruntguru, 17 November 2013 - 22:58.


#39 Lee Nicolle

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Posted 18 November 2013 - 03:33

Dry sumping decreases crankcase pressure. Crankcase pressure is caused by the components flailing around which in turn causes on hell of a mist of oil. However it is achieved crank scrapers and the like direct oil to the scavenges which are sucking air, oil and aerated oil The better the sump design the more reliable the engine to make more power. The less oil flailing around at the bottom of the engine means less detonation through oil contamination, less work for the rings to do wiping the bores.
BUT all engines need breathers, trying to control all this in a vacuum would be near impossible and possibly detrimental to the rings any way. And generally even engines scavenging the top still rely on gravity to return excess oil to the pan.

A pushrod engine requires far less top end oiling than OHC. Less oil to control going back down. Many oval track engines scavenge the 'outside' rocker cover. I have hear stories of qualifying engines with no top end oiling at all. May be good for a few laps. but the rockers and valve springs need to be lubricated and cooled. multiple cam engines with multiple valves and springs always are a chore to control the oiling

I am sure F1 engines are a real challenge as they nearly double the RPM of most other race engines,, except bikes and god knows how they stay together with the g forces as well as angles they get up too.
Though talking to my brother yesterday even a good chook chaser is very high maintenance. 20 hours to a rebuild is the recommendation. Dry sumped 14k rpm single cylinder with low oil pressure and high volume. More oil pressure evidently and they blow all the seals out!! As it is bearing life is very short.

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#40 indigoid

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Posted 18 November 2013 - 04:01

I am sure F1 engines are a real challenge as they nearly double the RPM of most other race engines,, except bikes and god knows how they stay together with the g forces as well as angles they get up too.
Though talking to my brother yesterday even a good chook chaser is very high maintenance. 20 hours to a rebuild is the recommendation. Dry sumped 14k rpm single cylinder with low oil pressure and high volume. More oil pressure evidently and they blow all the seals out!! As it is bearing life is very short.

 

I think you've cherrypicked a very highly-strung example. Was it a four-stroke? It does sound like fun, I must admit. The riding part, that is.

 

My last bike was good for ~128bhp/litre and ~10500rpm and over the 81000km I put on it, to mangle a phrase I think Greg used here once, "the bike fell apart around the engine". 10000km maintenance/service intervals. Valve clearances every 30000km but no adjustments ever required. Dry sump. If it wasn't for all the other parts failing I would probably have put another 120000km on it.



#41 gruntguru

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Posted 18 November 2013 - 05:44

BUT all engines need breathers, trying to control all this in a vacuum would be near impossible and possibly detrimental to the rings any way. And generally even engines scavenging the top still rely on gravity to return excess oil to the pan.
 

It is not uncommon to vacuum crankcases to 0.5 atmosphere (15" hg, 7.5 psi etc).



#42 malbear

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Posted 18 November 2013 - 07:33

thanks for all the interesting replies,

I have been a bit busy as it is shutdown on the potatoe farm , lots of refurbishing  welding and mill lath work for me.

many years ago when I was at the engine tech conference in Stutgart , there was much talk of going to 42 volts for cars in general to make the electric drives more efficient , there was a pommy group doing an electric water pump. 

could it go to 110 volts . more volts les amps and smaller motors to get the job done.

I gues safety issues would knock it out. 

well done thanks

Malcolm



#43 Greg Locock

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Posted 18 November 2013 - 09:06

Ah, the great 42V debacle. Given the efficiency of upconverters roughly (Vup-Vsource-0.6V)/(Vup-Vsource), the improvement in efficiency of motors in general, and inertia, I'm going to hazard a guess that 42V remains a niche app.

 

That being said if one big manufacturer took the plunge then I think everyone would follow. I'm too lazy to google, what's the predicted weight advantage for a typical car?



#44 indigoid

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Posted 18 November 2013 - 11:03

 

This video (admittedly about Bentley, so not quite the norm) shows the wiring loom at about 6:00. It's enormous! And interestingly they say it has optic fibre in it as well as the usual copper



#45 gruntguru

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Posted 18 November 2013 - 11:19

Pretty sure 42v has/had a lot to do with mild hybrid, starter/generators etc. The concept is actually 36v ie 3 x 12v batteries and max voltage under charging conditions of 42v - remaining at a level accepted as safe to handle.



#46 Lee Nicolle

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Posted 18 November 2013 - 22:10

I think you've cherrypicked a very highly-strung example. Was it a four-stroke? It does sound like fun, I must admit. The riding part, that is.
 
My last bike was good for ~128bhp/litre and ~10500rpm and over the 81000km I put on it, to mangle a phrase I think Greg used here once, "the bike fell apart around the engine". 10000km maintenance/service intervals. Valve clearances every 30000km but no adjustments ever required. Dry sump. If it wasn't for all the other parts failing I would probably have put another 120000km on it.

motocross bike 5 valve single Yamaha 400+cc

#47 Lee Nicolle

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Posted 18 November 2013 - 22:15

Ah, the great 42V debacle. Given the efficiency of upconverters roughly (Vup-Vsource-0.6V)/(Vup-Vsource), the improvement in efficiency of motors in general, and inertia, I'm going to hazard a guess that 42V remains a niche app.
 
That being said if one big manufacturer took the plunge then I think everyone would follow. I'm too lazy to google, what's the predicted weight advantage for a typical car?

And it will also be very heavy. More batterys, bigger charging systems and why? So we can fit more uneeded electric gizmos

#48 bigleagueslider

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Posted 19 November 2013 - 05:05

It is not uncommon to vacuum crankcases to 0.5 atmosphere (15" hg, 7.5 psi etc).

While a below ambient pressure in the crakcase is helpful, the main reason for using high-volume scavenge pumps on high-rpm race engines is to keep the crankcase as free of oil as possible.  With a high-rpm F1 engine, the oil in the crankcase is in the form of tiny droplets mixed with air. The windage (or hydraulic) losses created by the crank and rods passing through this oil/air mixture can be quite significant.  Since the oil is in the form of droplets mixed with air, the only way to scavenge the oil is to also scavenge the air it is mixed with.



#49 Lee Nicolle

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Posted 19 November 2013 - 09:59

On F1 I have no idea,, but the rest I do. IF you are creating 7.5lb of vacuum those pumps must be sucking a huge vacuum. The engines do create pressure with windage and compression leakage which will be several PSI positive, vented to the atmosphere itself 14psi or so. And 'real' engines drain to the bottom where they are scavenged,, and need to be vented so the oil flows down to the bottom.
Generic dry sump pumps do suck large volumes or aerated oil. The common 3 stage moves several litres a min. 4,5 stage will obviously have the capacity to do twice as much. But the oil will seldom be there so the scavenge sections are just eating them selves up. Which they do far too rapidly as it is.

And the more stages used the more power used. And with an electric motor the bigger the motor needed and the more alternator and battery required. Turn a dry sump pump over by hand just to crank up oil pressure before you fire an engine that has not been started in a while. Hard work!

On some converted production engines with a standard external oil pump the pressure section is the factory oil pump with a separate belt driven scavenge pump/s. Usually 2 stage.
On those engines you can make a simpler efficient wet sump. As you can baffle the well to reduce windage and surge. Just make an external pickup to the floor of the pan and block off the original. A deeper pan helps with this. With a big oil cooler acting as a deaeration device it works ok and generally keeps the engine together. With less power loss. But for reliability nothing beats dry sumping where you are allowed to use it. And you can get the engine appreciably lower too. You can do this still with an internal pickup but it will never be as simple or as reliable.

#50 bigleagueslider

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Posted 21 November 2013 - 04:31

It's not the level of crankcase vacuum itself that matters with regards to the power consumption of oil scavenge pumps, it's the pressure differential between the pump inlet and discharge.  While the pressure differential between the crankcase and atmosphere can never exceed 14.5 psi, the pressure differential in the scavenge pump's discharge circuit can easily be several times that.