Is the Diesel dead for autos?

Edited by imaginesix, 23 May 2016 - 17:15.

All the space in front of the engine (assuming front engine) is wasted so far as crumple zone is concerned, if you are trying to eyeball crash results. The real passenger protection bit happens between the front wheels and the A pillar. All the bit in front of the engine does is decelerate the engine. (Very roughly)

So if there is no engine in front of the cabin to keep out of it in the event of a frontal collision the amount of energy that needs to be dissipated by the crumple zone is less right?

Going back to my original point most of the posts so far picking my POV apart have only shown how much current car design thinking is dictated by the need for a large heavy PU in the front of the car that has to be directly mechanically connected to the driven wheels.

Tesla supporters claim that their cars are marketed at forward thinking types and its certainly true that most of the Tesla S buyers are early adopters willing to overlook some of the disadvantages of EVs as long as they get a cutting edge product.  Therefore shouldn't this demographic also be more willing to accept a car design that is nothing like what we've had before and pushes the boat out?

I'm not a car designer or engineer (very far from) so I'm not sure what new layouts are possible with EVs but I want Tesla and the others to fire my imagination.  Thus far they have all failed miserably.

 

Squiggle down a quick model of two constant force elements in series, and 2 masses. You want to minimise the acceleration of the second mass, and you don't really care what the first one gets up to.

OK - lets say the engine is 250 kg and the rest is 750 for a total of 1000 kg.

1.  If the constant force elements are equal at 7,500 kg (75 kN) each, the front section will start crumpling at 7.5 g (the rear section remaining intact for now). Once the front section is fully collapsed, the rear starts to collapse and the decel' is 10 g.

2.  If the front element is 10,000 kg and the rear is 7,500 both sections will crumple simultaneously (at 10 g). Any movement of the rear mass toward the front mass will reduce the decel' of the rear mass, so the rear element will not crumple but remain at a point of incipient collapse until the front element is fully collapsed - at which point the rear element collapses - still at 10 g.

Either scenario (or any in between) puts the zone ahead of the engine to good use. . . . .

Waiting for Greg to point out the flaw in my analysis.

I'' do it my way, Let's see if this makes sense.

Second element is designed to collapse at 20g, so if the cabin weighs 750 kg, it collpases at 15 kN. Front element collpases at 60g say, it has to handle 15 kN from the second one plus 250kg (engine)*60g=30 kN

So from 50 kph into a concrete block the front crush zone collapses by 164 mm, rear one by 492mm-164=328mm (good luck finding that space in a car!) In reality the cabin decel can be higher than that because of seatbelts and so on.

So a wiser designer would, for a fixed total length of crumple zone, waste less of it on the engine, and more on the cabin, maybe take the engine to 120g, crush length 82mm, and then put that extra 82mm into the second stage, dropping the cabin decel a bit.

Think your kN numbers are low by a factor of 10.

I need to think through this further but my intuition says the cabin is decelerating at its design rate throughout the front zone crumple event and over the full distance of the front crumple. So energy subtracted from the cabin is the same whether the crumple is ahead of or behind the engine. (assumes front zone stiffness equal or greater than "scenario 2" above.)

yup, i was wrong by a factor of 9.81.

Edited by Greg Locock, 24 May 2016 - 07:40.

Given that the engine/gearbox and cabin  are , initially at least, elastically connected masses how do you allocate the two crumple zone lengths/strengths so the front crumple zone both stops the engine AND starts the deacceleration of the cabin?

Also , just to make it more complex, how about a one side impact where the engine can  sort of, fly straight past the obstacle?

Edited by mariner, 24 May 2016 - 09:14.

The elastic bits are useful - being the initial deflection that absorbs the energy of a small bump without damage. OTOH the energy absorbed (per mm) is only about half what you get during crumple so you don't want to design with too much elastic deformation.

As I said a couple of posts back - crumple strengths for each zone should be allocated in proportion to the total mass behind the zone.

Designing for the traditional head on into a concrete block requires one set of compromises. Offset crash requires a whole other set of compromises, some of which hurt the first lot. For example we often use breakaway bolts on the front subframe. Terrific in a full frontal crash, but not much good in an offset crash as they bind. So redesign them to work in offset crash and now they break in a single wheel pothole, or kerbstrike. Ah well, it keeps them busy.

Whats wrong with a solid rollcage/Tubeframe support cage? ala. Racecars?

Whats wrong with a solid rollcage/Tubeframe support cage? ala. Racecars?

Don't know if here is the right place, but since so much was said around here about Tesla here it goes:

http://www.macrumors...ndup/apple-car/

 

 

Apple's massive hiring spree has led Tesla CEO Elon Musk to refer to the Apple Car as an "open secret" in the car industry. According to Musk, the hundreds of engineers Apple has taken on make it clear there's an electric car in the works. "It's pretty hard to hide something if you hire over a thousand engineers to do it," he said.

http://appleinsider....massive-project

 

 

Apple does not disclose work on future projects, and products are often in development for years before shipping, but the swelling R&D outlay signals work on a massive project beyond expected upgrades. Rumors indicate the company is deep into development of an electric vehicle referred to internally as "Project Titan." Breaking into a heavy industry is no small task even for one of the world's largest companies, but billions of dollars in investment capital would make a nice seed fund. 

Is that really much?

http://www.autonews....-spending-in-15

 

 

Top 10 automotive r&d spenders, 2015

VW $15.3 billion Toyota $9.2 billion Daimler $7.6 billion GM $7.4 billion Ford $6.9 billion Honda $5.5 billion BMW $5.5 billion Nissan $4.6 billion Denso $3.6 billion FCA $3.4 billion

Or you could have asked me. About 5 of our more talented engineers and one other have been headhunted by Apple. The vehicle dynamics of iPods is probably not what they are working on.

Whats wrong with a solid rollcage/Tubeframe support cage? ala. Racecars?

For a road car everything.

For a racecar is stiffens up the middle bit and depending how extensive the cage is it defeats the crumple zones which makes the car handle better though sometimes you do worry about large crash impact.

Reports of the death of diesel cars may be overstated..... "Demand for diesels grew by five per cent with petrols falling by 0.6 per cent."  Auto Express 6 June

Or you could have asked me. About 5 of our more talented engineers and one other have been headhunted by Apple. The vehicle dynamics of iPods is probably not what they are working on.

What is 'the other' working on 

Oh what a tangled web we weave when in lab. testing we believe!

http://www.bbc.co.uk...siness-36589106

Yes, maybe it is

http://www.bbc.co.uk...siness-37287129

Renault and France have a very long Diesel history, with french taxes on diesel always kept lower than petrol to encourage diesel usage.So if this report is true it is huge step.

The article is about high diesel emissions in cold weather. Not much you can do about cold starts, but surely once warmed up, the intake air could easily be heated (using coolant or exhaust heat) with emissions levels returning to normal.

OK - lets say the engine is 250 kg and the rest is 750 for a total of 1000 kg.

1.  If the constant force elements are equal at 7,500 kg (75 kN) each, the front section will start crumpling at 7.5 g (the rear section remaining intact for now). Once the front section is fully collapsed, the rear starts to collapse and the decel' is 10 g.

2.  If the front element is 10,000 kg and the rear is 7,500 both sections will crumple simultaneously (at 10 g). Any movement of the rear mass toward the front mass will reduce the decel' of the rear mass, so the rear element will not crumple but remain at a point of incipient collapse until the front element is fully collapsed - at which point the rear element collapses - still at 10 g.

 

Either scenario (or any in between) puts the zone ahead of the engine to good use. . . . .

 

Waiting for Greg to point out the flaw in my analysis.

Not many one tonne cars these days, I doubt any electric ones at all and probably not diesels either. Heavy batteries or heavier engines and transmissions make these vehicles heavier than their petrol brothers.

Some smaller and med size diesel cars actually use different tyres, effectively with more load rating. I am told the same for Prius in comparison too its base the Corrolla. 

Edited by Lee Nicolle, 08 September 2016 - 11:06.

Not many one tonne cars these days...

Mass is a problem. A Ford Fiesta weighs one ton. A Ford Focus with driver weighs 1.5 tons. All of these clever new cars are too fat.

Depending on view point, the Ford Focus replaced the Ford Anglia 105E (740 kg) or Mark 1 Escort (810 kg) or Mark III Cortina (990 kg). 

Mass is a problem. A Ford Fiesta weighs one ton. A Ford Focus with driver weighs 1.5 tons. All of these clever new cars are too fat.

 

Depending on view point, the Ford Focus replaced the Ford Anglia 105E (740 kg) or Mark 1 Escort (810 kg) or Mark III Cortina (990 kg). 

All "with driver"? (My 2006 Focus has a curb weight of 1.3 tonnes and I don't weigh 200kg)

Weight gain is always good for a chuckle. Easy to do on paper, but it would be a more interesting exercise to put the modern vehicle side-by-side with the older comparison vehicle and compare them point-by-point. Odds are the modern car wins on EVERY point including cost - despite being 30% heavier.

Your Focus has A/C, catalytic converters, electric seats, 6 speakers, a subwoofer, electric windows, and about 3 times the power of the Anglia. It has tires that are twice as wide that last twice as long and grip 20% better, with disc brakes. If you crash it in into a tree then you will probably live. If you turn it on its roof you will probably live.It has airbags all over the place. There's a good chance its mpg is better than the Anglia (my 1300cc RWD  escort got 28 mpg after  a lot of remedial work by me, before then it was 24 mpg from new), and of course its emissions are way lower and it is quieter. The only Focus that weighs more than 1500 kg has a 350hp engine and AWD. Not many Anglias managed that.

I'm not saying Focus is a particularly good example of weight management, although if you plot kerb weight vs shadow area (track*wheelbase) you'll find most cars of a given age fall on the same line, but all those toys that new car buyers want do have a mass.

Exactly.

I doubt the Anglia would even fall in the same category if you compare occupant space, boot (trunk) capacity, load capacity etc.

My dad had a Mk1 Golf and son in law owned a Mk 2. Dad was giving an armchair to son in law, so the plan was to meet half way and transfer the armchair. But it didn't fit in the "improved" Mk 2 Golf...

I'm not rosy eyed about cars from the past. Build quality, paint quality, mileage took a big leap over the last 30 years -- although the only time I've been taken home on a low loader was with a modern car; if I had adopted my brain, I could have fixed the problem. Many of the old cars disparaged on programmes like Top Gear were very clever designs which were badly made. Today you can build a comparatively weak design which won't provide consumer joy but doesn't break down.

Limitations of the ICE meant that old cars were built light. With a few exceptions, cars used steel shells and panels -- GRP and aluminium usage was notable. Few designs were analysed by a computer; CAD was adopted in the late 1970s; old cars were designed on paper so if CAD had been used, they'd be lighter or stronger in the necessary places. ICE limitations also meant that cars couldn't afford the efficiency losses for big alternators (dynamos, even) or pumps. 

I wouldn't want to lose some of the conveniences of a modern car. The seats in my modern Peugeot are as comfortable as a 1970s Saab or Triumph -- and they weigh about the same. So there's a weight saving opportunity. The radio is similar in form and mass with loads more functionality, but speakers add a few pounds. There is twice as much wiring as a 1970s car, light clusters are twice the size and presumably twice the mass. Airbags add pounds -- whatever happened to the seat belt technology which tightened belts before impact?

Reduce mass. In stop-start traffic conditions, it'll improve efficiency whatever engine is driving the car.

All "with driver"? (My 2006 Focus has a curb weight of 1.3 tonnes and I don't weigh 200kg)

Perhaps Wikipedia Focus owners are a bit chubbier than you ;-)

Diesel models weigh a bit more than petrol cars. Fuel capacity is between 53 and 62 litres -- let's say 40 kg for fuel. 11 stone (154 pounds or 70 kg) for driver. Let's split the difference at 1.4 tons for a Focus.

Mass is a problem. A Ford Fiesta weighs one ton. A Ford Focus with driver weighs 1.5 tons. All of these clever new cars are too fat.

 

Depending on view point, the Ford Focus replaced the Ford Anglia 105E (740 kg) or Mark 1 Escort (810 kg) or Mark III Cortina (990 kg). 

Mass isn't a problem in an of itself. It's the deleterious effects of additional mass that are the problem. Reduced performance, fuel efficiency. Yet if you compare the Focus on those grounds, it's likely better. So why be concerned whether a car weighs as little as a pea or as much as a planet? Worry about the attributes that matter.

There's a rather nice paper around that looks at the effect of mass vs fuel economy. I haven't been able to find it again. Basically from what i remember the penalty is halved if you have regen.

Now this ignores the prime mover part of the deal. If you add a diesel to a B car your mass increases by say 50 kg, but your mpg improves by what, 10 mpg? or more?

A B car?

Golf size car?

 B = Fiesta sized. I thought they were industry standard terms but apparently not, it's a european thang. https://en.wikipedia...icle_size_class

I think it might originally be a US thing. When I worked fro Chrysler International in the early 1970's all the product planning froms had A, B ,C, D car across the top and you filled in the features etc to price the car vs competiton. The categories seemed very US to the people there from Euro mfrs.

Incidentally the "rules " of pricing then were weird. you multiplied wheelbase by a factor for your base price then added a flat price per option which was several times cost. sounds OK but if you looked up the manufacuring cost per inch of wheelbase it was the same as price per inch. So you could logically "prove" Einstien was wrong because infinite option profit could be acheived on a zero length car.

Edited by mariner, 20 September 2016 - 08:31.

 B = Fiesta sized. I thought they were industry standard terms but apparently not, it's a european thang. https://en.wikipedia...icle_size_class

Read a few UK car reviews, Greg. Nobody writes about alphabetic segments; the model is a small family car, executive or a similar description.

It might have been different a generation or two ago. When GM designed the Vauxhall Chevette for the UK market, it was a member of a world wide family of cars (Opel Kadett C, Holden Gemini) which have few interchangeable parts. In Europe, you could buy a a GM T-platform car in Opel or Vauxhall flavour.

The Italian motor press uses the same alphabetical designations and they are well and widely understood.  I thought it was standard in continental Europe.

Bit of a waste of a wiki link there Charlie. And to be honest why would I read car reviews? 

And to be honest why would I read car reviews? 

To learn what the enemy thinks? I don't go out of my way to read car reviews because I was once paid to read them (for market research comparison versus computer data). Here is a pseudo randomly selected UK press review of a popular car (http://www.autoexpre....uk/peugeot/308). Google picked the review.

There is no mention of alphabetic segments but you are told right away which cars are comparative models. Insurance groups -- a significant cost of ownership factor -- earn a separate section. Perhaps, as "desmo" suggests, the classifications are used and understood in Italy. Europe is a big place, so once again Brits and Italians differ.

So you didn't read the wiki link?

Mass is a problem. A Ford Fiesta weighs one ton. A Ford Focus with driver weighs 1.5 tons. All of these clever new cars are too fat.

 

Depending on view point, the Ford Focus replaced the Ford Anglia 105E (740 kg) or Mark 1 Escort (810 kg) or Mark III Cortina (990 kg). 

A local historic racer has a twin cam Mk1 under 800kg legally with a steel cage, a lot of thought has gone into weight reduction and redistribution.

Read a few UK car reviews, Greg. Nobody writes about alphabetic segments; the model is a small family car, executive or a similar description.

 

It might have been different a generation or two ago. When GM designed the Vauxhall Chevette for the UK market, it was a member of a world wide family of cars (Opel Kadett C, Holden Gemini) which have few interchangeable parts. In Europe, you could buy a a GM T-platform car in Opel or Vauxhall flavour.

I see quite a few Opel Kadetts in historic rallying on videos. They appear too look the same as the Gemeni until you look again.

Did they use the Isuzu engine and the torque tube rear? Remember the Gemeni was simply an Isuzu with a Holden badge. They were assembled here, trim, glass etc was local.

I see quite a few Opel Kadetts in historic rallying on videos. They appear too look the same as the Gemeni until you look again.

Did they use the Isuzu engine and the torque tube rear? Remember the Gemeni was simply an Isuzu with a Holden badge. They were assembled here, trim, glass etc was local.

An ex-girlfriend owned a Kadett C but I rarely worked on it. You might want to ask the question on TNF when a suitable topic arises.

So you didn't read the wiki link?

I comprehended it as a European, Greg. Europeans, including Brits, pick standards which work best for themselves. As I suggested, insurance ratings for a model are very important in the UK. In the UK, one of twenty odd countries.

I see quite a few Opel Kadetts in historic rallying on videos. They appear too look the same as the Gemeni until you look again.

Did they use the Isuzu engine and the torque tube rear? 

AFAIK the engines in the Kadett C were Opel's own.  The small (1200cc) motor was their pushrod engine from earlier Kadetts and the larger engines (2 litre on the GT/E) were those also used in the Ascona range.  I believe they all used a torque tube rear axle, although it may have been removed for competition cars.

Edited by BRG, 25 September 2016 - 15:50.

Well, I never thought that Dieselgate etc would happen but maybe diesel is - heading to be -  dead as FCA ( Fiat) have just annouced they are stopping diesel for cars soon.

https://www.autocar....el-engines-2022

In wealthier nations, we see knee jerk responses to revelations of diesel emissions cheating. Customers have stopped buying diesel cars as much and legislators are looking at diesel car usage in cities. What would have happened if it had been demonstrated that manufacturers were gaming the emissions figures for petrol ICE cars?

When considering combustion factors for ICE design -- whatever the fuel -- you have the following:

* Fuel use efficiency -- with enough power and torque to operate safely.

* CO2 emissions. I'll ignore CO on the basis that it is so easily converted to CO2 in the natural environment.

* NOx emissions.

* Particulate emissions -- soot, unburnt fuel.

* Sulphur compound emissions -- probably not a problem with cars, certainly one for marine and farm use diesel in developing nations. I'll ignore this factor because it can be best addressed by cleaning up fuel.

In order to achieve the first on the list -- fuel use efficiency -- designers have to be creative whilst juggling the next three factors -- CO2, NOx and particulate emissions. It turned out that some people at car manufacturers found a few engineers prepared to create cheat systems for diesel engines. And so public opinion -- a significant part -- determined that diesel is "bad". Nobody considered whether similar cheats have been applied to conventional or hybrid cars with petrol ICEs. 

NOx emission limits matter a lot. Hybrid engines in F1 cars achieve almost incredible thermodynamic efficiency (and consequentially low CO2 emissions) at a cost of huge NOx parts per million. Pumping NOx from the exhaust pipe at a race track or open country road isn't much of a problem. Like CO emissions, they are absorbed locally in open spaces. Mostly.

NOx is a city problem but so is urban planning. Streets surrounded by tall buildings -- canyon avenues -- create regions where pollution is never blown away or absorbed. Underground industrial plant for telecoms, power distribution or air conditioning increases temperature at ground level. That should be good for NOx recycling or absorption into the natural environment -- but there is insufficient wind or nature for it to happen.

I think that diesel cars have a place outside big cities. I also think that environmental campaigners need to think a bit bigger about how pollution happens.

https://www.cleanene...lia-report.html

Australia is already > 13% renewable although half of that is hydro (which is available around the clock). I think "X" in that situation is greater than 20% (depending largely on the mix of other renewables). I wonder how much of that hydro could be converted to operate as pumped storage when required? That alone would provide a huge buffer for intermittency in other sources.

 

The government has already committed to 20% renewables by 2020 and (28%?) by 2030 while the other major party has a policy of 50% by 2030.

Ask Tassy about hydro! The HEC has nearly run Tasmania over the decades but no water= no electricity.

I suspect the Snowy Scheme is probably safer but not by much.

The problem is with all 'renewables' is that they are not base load. And never will be.

I beleive similar has happened in the US as well with the Colorada River?

In wealthier nations, we see knee jerk responses to revelations of diesel emissions cheating. Customers have stopped buying diesel cars as much and legislators are looking at diesel car usage in cities. What would have happened if it had been demonstrated that manufacturers were gaming the emissions figures for petrol ICE cars?

 

When considering combustion factors for ICE design -- whatever the fuel -- you have the following:

* Fuel use efficiency -- with enough power and torque to operate safely.

* CO2 emissions. I'll ignore CO on the basis that it is so easily converted to CO2 in the natural environment.

* NOx emissions.

* Particulate emissions -- soot, unburnt fuel.

* Sulphur compound emissions -- probably not a problem with cars, certainly one for marine and farm use diesel in developing nations. I'll ignore this factor because it can be best addressed by cleaning up fuel.

 

In order to achieve the first on the list -- fuel use efficiency -- designers have to be creative whilst juggling the next three factors -- CO2, NOx and particulate emissions. It turned out that some people at car manufacturers found a few engineers prepared to create cheat systems for diesel engines. And so public opinion -- a significant part -- determined that diesel is "bad". Nobody considered whether similar cheats have been applied to conventional or hybrid cars with petrol ICEs. 

 

NOx emission limits matter a lot. Hybrid engines in F1 cars achieve almost incredible thermodynamic efficiency (and consequentially low CO2 emissions) at a cost of huge NOx parts per million. Pumping NOx from the exhaust pipe at a race track or open country road isn't much of a problem. Like CO emissions, they are absorbed locally in open spaces. Mostly.

 

NOx is a city problem but so is urban planning. Streets surrounded by tall buildings -- canyon avenues -- create regions where pollution is never blown away or absorbed. Underground industrial plant for telecoms, power distribution or air conditioning increases temperature at ground level. That should be good for NOx recycling or absorption into the natural environment -- but there is insufficient wind or nature for it to happen.

 

I think that diesel cars have a place outside big cities. I also think that environmental campaigners need to think a bit bigger about how pollution happens.

I am not and never will be a fan of diesels. Dirty stinking thing that you get filthy hands just refueling. 

BUT for a larger 4wd [not SUV] they do make sense as the bottom end torque is great for low speed work. As for the rest,, ban the bloody things!

I keep seeing people who want a manual petrol ute and are stuck with a turbo diesel auto as that is all the manufactures sell. And most dislike or hate the things. And they cost a LOT more to service and maintain with all the whiz bang electronics.

Though now the newest 'class' from V8 Stupid cars is diesel utes,, but they are manuals, and slow and it seems unreliable.  3 or 4 of the field of 10 broke down every race. I watched a couple of laps on the weekend telecast and they are exciting as watching grass grow! And slower than Robby Gordons jumping trucks.

Edited by Lee Nicolle, 06 March 2018 - 06:05.

The problem is with all 'renewables' is that they are not base load. And never will be.

 

Completely incorrect.  Renewables + storage = base load.  The storage part of the equation is only partly there at the moment, but it's constantly improving.

Base load is soooo twentieth century ...

Baseload was term that was relevant when we only had coal, with a bit of hydro thrown in. 

With the variety of power sources available today, and with a potentially significant additional one (pumped hydro) yet to make an impact, the mix of generators is much more complex.  What matters is whether the system can supply the power required when it is required.

On a related note, I see a press comment to the effect that the supply of household solar generation is becoming so great that the price will drop.  The industry needs to be very careful here, the falling price of batteries is nearing breakeven point, and when that happens, large numbers of people will desert the grid, seriously disturbing the pricing model that sustains the retail, distribution and production of electricity (the latter two will be most affected).  Already standing charges are becoming a much more significant part of the electricity bill, and as these and unit prices are increasingly used to offset falling demand, the maths lean more towards the off-grid solution.  When the crossover occurs the retailers will see the number of consumers starting to fall, and the distributors and producers will see their demand falling.   This then sets up a classic death spiral of increased price leading to reduced demand leading to increased price and so on.  I find it difficult to see how to prevent this, the only questions are the timeframe for the initial phase, and the rate thereafter. 

I am sitting on a 10kw solar array, watching my electricity bill and the price/lifespan of batteries.  The up-front financial commitment is a big hurdle for me, but fortunately I have had a good education and can do my sums ...