h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Four-Stroke Internal Combustion Engines - Copied from A633232 - A13298330
Author: six7s - U192113

Following a suggestion made in another PR thread (for A3421289 - Atmospheric Pollution from the Internal Combustion Engine in the Urban Environment by U612575 TRiG) I have copied this entry from A633232, as written by Xuenyl who last posted on 17 September 2001



Please note:
Although I am NOT all that knowledgeable about the mechanics of Internal Combustion Engines, it seems to me that this entry, as it is 'today', already merits inclusion in the Edited Guide.

However, if anyone has any worthwhile suggestions, I am more than happy to incorporate them into this copy of the entry

Assuming there won't be any major changes, I feel no need to be credited for this simple copy and paste exercise

Cheers
six7s



ORIGINAL ENTRY DATA:
Entry ID: A633232
Edited by: Xuenyl U181569
Date: 17 September 2001

Hi Six7's, As you say a good article. On first read through some points to consider.


"The electrical charge, which normally has a relatively low voltage (12V) is transmitted to the coil, which is essentially a transformer which converts it to high voltage at the expense of current. Low tension leads then carry this charge to the distributor."

is fed to the coil.

The high voltage generated by the coil is then fed via a high tension lead to the distributor which then distributes the high voltage to the 4 plug leads, also known as high tension leads [HT]

On early distributors contact breakers, known also as points, were used to make and break a contact to energergise the ht leads. The points were fed by a low or vehicle voltage of 12volts.Because the voltage with engine running and the charging system operating is an average of 13.5 volts points systems had a condensor fitted in the distributor in order to keep the voltage at the points a constant 12volts.

Electronic ignition modules later replaced the points system, basically a small unit, some attached to the outside of a disributor, which did the same job as points except it was now done electronically.

Further advancement is the distributorless ignition system where the ignition is controlled by an electronic control unit, {ECU}.

The charging system on cars generally run at an average of 13.5 volts although the batteries are usually 12volts.The alternator also can give out in excess of 70amps current to run modern car electrics.


"This is achieved by a rotating arm at the centre of the distributor16 which touches each of four equally spaced contacts in turn."

The rotor arm passes the contacts, does'nt touch them.

"the speed of the rotating arm is controlled by a small tube from the carburettor"

Incorrect. The rotor arm speed is governed by the speed of the camshaft as the distributor is driven by the camshaft either via a gear or offsey keyway. The vacuum pipe seen on early distributors actually moved the base plate in the distributor which in turn had the effect of advancing the timing marginally, the unit shaped like a bellows on the side of the distributor was called the advance retard unit.

I'll have another good read of this later, I see no mention of diesel engines, perhaps that was intentional, may warrant an article on it's own perhaps?

Oh and my usual err gripe, too many footnotes!

regards,
ST.

Hi six7s

You have Xuenyl as a Referenced Researcher, but if he wrote this, he needs to be given joint credit, so remove him from the credits tag and add him to the box "Edit the Researcher List" thus:

After your User number, put a comma, then his number, then click "Set Researchers" then click "Update entry". Sorry if it's not the same in the skin you're using, I'm an old-fashioned Goo-user

Apologies if you already knew how to do this

GB

Hi ST and GB,

I will make a start in a few minutes (in Goo )

I'm posting now cos I've had a thought...

Because I didn't write the entry, I don't (immediately) recognise which bits (in ST's) post are quotes and which are suggestions

Of course, this ain't an insurmountable problem... I can simply use that grey thing in my head...

But...

It would be easier for me if << quotes >> from the entry were easily distinguishable (is that a word?) from >> suggestions <<

hi Six7's,

The items in " " are quotes from the article, the others are just suggestions/ correction/additions. I'll be more specific in future though, about that.

I'll get round to the other when I'm back later next week.

ST.


Brunel forever.

Hiya ST

Thanks... I did figure it out (after my 2nd coffee)

Now I'm trying to figure out what to add, replace etc...

I get the impression you think that quite a bit should be added regarding the 'electrics'

I'm not so sure... I say this cos I see this entry as an overview of the whole 4-stroke system, and the 'basics' are (as the word 'basic' suggests) the same today as they were in Otto's day: Suck, Squeeze, Bang, Blow

I have a hunch that dwelling on the 'Bang' might better be done in another entry

Oh, and I must ask if/why you want the word 'transmitted' to be substituted with 'fed'?

Transmitted makes it sound like wireless ignition. The general term in the trade is electrical feeds.

The electrical detail is really to clarify what was already there, some of the info re high tension volts etc was incorrect, so it's either a case of remove the electrical detail or at least have the correct detail. Same applies for the info on things like the 'tube from the carb to increase speed of rotor arm'. technically incoreect. If it needs to be in the article then again needs clarification.
Vehicle electrics are complicated and take a bit of explaining to the lay person, would certainly warrant an entry on their own but there is quite a bit on them in this article.

ST.

<< ... so it's either a case of remove the electrical detail or at least have the correct detail ... >>

I agree wholeheartedly

I'll be back in around 12 hours or so to work on incorporating your suggestions - in the meantime... RL beckons

Managed to sneak away for a bit and used the time to add ST's ideas and a link suggested by 'Radox the Green'

Both added to the researcher's list

Also, incorporated a couple of the footnotes into the body

And added a link from Daimler-Chrysler to an EG entry on McLaren Cars

Updated

Only one footnote remaining

and now a little easier to read

You don't need "ORIGINAL ENTRY DATA:
Entry ID: A633232
Edited by: Xuenyl
Date: 17 September 2001"

in the entry and you can removed the "- Copied from A633232" in the title, because it's your entry now

with this, six7s

Thank you ma'am

I know the suffix in the title and the 'pre-into' are superfluous, but they're doing no harm and if/when a sub gets hold of it...

In the meantime... I figure it tells any PR regulars what's what from the outset

Neat Entry, good subject, nice find.

The last paragraph in the Electrical Systems section could be omitted because it repeats the last sentence of the third paragraph.

And here's one for the petrolheads to argue over, but aren't OHC engines less efficient (not more as the Entry claims) than pushrod (or OHV) engines as a rule? An OHV configuration develops its maximum power at lower revs, therefore you get more torque for the same energy input over most of the range.

Only at maximum revs will an OHC engine burn relatively less fuel (but by then Efficiency has been left on the hard shoulder and Irresponsibility has taken her place in the passenger seat)

Hi Pin,

Thanks for the heads up

I have had a fiddle with that section and suspect I have made it worse

So... any help will be welcome: see <./>A13298330#help</.>




As for OHCs... I suspect the word 'efficiency' has two distinct meanings...

OK - where you're getting confused is that it's not 12 V that's supplied to the points. It's a high tension feed by that point - that's what the coil's for (which you seem to have missed out).

This should help : http://auto.howstuffworks.com/ignition-system.htm

But if it was me, I'd just leave it at something like :

- 12 V at the battery (because that's what you get from a practical lead-acid cell, and it's a safe voltage for a permanent static power source)
- Feeds a high current (ten of amps) through primary coil, and the high tension is induced when the secondary circuit goes open.
- This high tension pulse (about 50 kV) is fed to the various spark plugs via a distributor which controls the sequence of the cylinders.
- In modern engines, the distributor is a solid state device (power transistors gated by a microchip)

Then I'd probably write far too much about the valve sequence : timing, scavenging etc, because the mechanical bits are far sexier, don't we all agree?

hi six7's, ok, before I make further comment I see you are asking for expert assistance on this article. Can I point you to this, http://www.bbc.co.uk/dna/h2g2/brunel/F123091?thread=3223684&latest=1 Also to add, 25years in the trade gives me a modicum of experience I think. ST.

Hi ST,

Sorry that what I wrote made it seem like I didn't regard you as an expert

The opposite is true!

... an impression I got after reading what you last wrote... which I comprehensivly mucked up when I tried rewriting it so that the past/present/future tenses were consistent with the 'original' entry

I think the confuzzlement set in for me when I got to the bits dealing with the chronology of 'developments' from points to EFI (or whatever it's called) and then I jumped ship - as RL beckoned yet again

Although there will be interruptions, I do have time for this entry... Hope you still do too

Perhaps it may be easier on the electrical/ignition system to say something along the lines of

The ignition system has 2 main circuits, a low tension [LT] and a High Tension [HT] which in turn produces the spark required by the plugs to fire the fuel mixture thus the engine runs.
Quickest way to identify them is simply look at the size of the cables used, LT are thin cables HT are thick. Thats putting it in it's most basic form to say the least and is a guide only.

The information given in Post 16 is incorrect although obviously given with good intentions.The current and voltage rates quoted are incorrect for one thing.There is systems voltage and battery voltage as well.

Ref OHC and OHV and efficiency, well, from an engineering point OHC is more efficient in lots of ways. If you require a breakdown on the pro's and con's I can certainly give one.

ST.

<< However, if anyone has any worthwhile suggestions, I am more than happy to incorporate them into this copy of the entry >>

Me, post 1 above



Or... in other words... yes please!