electronic throttle
in [Technical]
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From: clare on 8 Mar 2010 19:28 On Sun, 07 Mar 2010 22:24:45 -0800, jim beam <me(a)privacy.net> wrote: >On 03/07/2010 02:47 PM, clare(a)snyder.on.ca wrote: >> On Sun, 07 Mar 2010 08:24:21 -0800, jim beam<me(a)privacy.net> wrote: >> >>> On 03/07/2010 08:10 AM, Bill Putney wrote: >>>> jim beam wrote: >>>>> On 03/06/2010 08:26 PM, Bill Putney wrote: >>>> >>>>>> I don't necessarily disagree with the rest of your post, but that part >>>>>> of your post is definitely incorrect. Have you ever played with your >>>>>> power brakes while simultaneously pressing the accelerator? Anything >>>>>> more than one or two initial stabs at the brakes depletes the vacuum >>>>>> stored in the booster, and with even slight power simultaneously being >>>>>> demanded of the engine, the vacuum is not enough to directly power the >>>>>> brakes, much less re-charge the vacuum in the booster. >>>>> >>>>> i have done this. with the engine off, the vacuum remains until the >>>>> pedal is released - thus if you stomp the pedal and keep it there, you >>>>> don't need to keep replenishing the vacuum. and you will stop the car. >>>>> with the engine running, there is no vacuum issue, and the brakes are >>>>> still powerful enough to stop the car. on my honda anyway. >>>> >>>> I have real trouble believing that a large majority of people would, in >>>> a sudden inadvertent acceleration situation, be content to press the >>>> brakes one time and not try to pump them once or twice. >>> >>> why? if the car in front of you suddenly jams on their brakes, do you >>> apply then release your pedal? i think your answer is "no" - unless >>> you're skidding and know what cadence braking is. and if you know what >>> cadence braking is, you should know that to stop a car with the engine >>> on full throttle, you apply the brakes hard and quickly - you don't >>> monkey about with multiple brake applications that can cause excess >>> heating and fade. >>> >>> >>>> After that, the >>>> brakes will be almost totally ineffective because of loss of vacuum. >>> >>> no. fade maybe, but vacuum is always present if the engine is running. >>> even if it's not, you still have vacuum reserve for three applications. >>> >>> >>>> >>>>>> People don't believe that, but try it on your car: On a deserted road at >>>>>> highway speed, stab the brake pedal a couple of times while holding the >>>>>> gas pedal down a little bit to load the engine slightly (this works >>>>>> anywhere from slight to WOT throttle). I guarantee you (unless your >>>>>> brake booster gets its vacuum from something besides the intake vacuum - >>>>>> like a separate electric motor-driven vacuum pump) that after two or >>>>>> more stabs at the brake pedal, the braking power will be extremely low - >>>>>> so low that the engine will have no trouble overpowering the brakes. No >>>>>> vacuum in the booster essentially equals no brakes. >>>>> >>>>> with respect, i think you're confusing vacuum with fade... >>>> >>>> No - I'm not. While you could certainly induce fade with a certain >>>> prolonged script of usage of the brakes, what I'm talking about is true >>>> over what I would say would be the real world typical scenario (before >>>> the fade issue becomes real - which - yes - it would over a longer >>>> period, but not likely if the 2 or 3 stabs had already occurred in the >>>> relatively short period that I would expect). It is a fact that the >>>> vacuum cannot recharge with almost no vacuum in the intake - it doesn't >>>> recharge by magic. I guarantee you that after a third stab of the brakes >>>> on an engine vacuum-driven power brake car, the brakes will loose the >>>> fight with the engine - fade has nothing to do with that over the first >>>> few seconds that we would be talking about (during which the first 2 or >>>> 3 stabs would occur real world). >>> >>> if that is your experience, then i think you must have a vacuum leak. >>> even with wide open throttle, there is sufficient vacuum in the manifold >>> to create significant braking assist. >>> >> >> Sorry Jim - but you are wrong. >> A diesel engined vehicle with a mechanical vacuum pump would work as >> you envision - but under any substantial load there is not enough >> manifold vacuum produced to provide full braking assist. > >i didn't say "full". OK then - lets be accurate and say "adequate". Won't get that either. > > >> With both >> feet on the brake pedal a strong man MAY be able to provide enough >> brake line pressure to stop the car at half throttle. > >/if/ the driver has pressed and released the pedal a couple of times. >why they would do that though is something i don't follow.
From: clare on 8 Mar 2010 19:33 On Sun, 07 Mar 2010 22:35:12 -0800, jim beam <me(a)privacy.net> wrote: >> >> Some people were taught and developed a lifelong habit of pumping brakes. > >some??? damned few dude - that's why we have abs. The vast majority of drivers on the road learned to drive before ABS even existed. And ABS (and "pumping" the brakes) is ONLY usefull for stopping (straight) in slippery conditions > > >> >>>>>> Admittedly, my theory that some percentage of drivers would pump the >>>>>> brakes is not provable as far as I know, but I do state it as >>>>>> conjecture, not as fact as you are stating your argument. >>>>> >>>>> with respect, you're projecting your own behavior as representative of >>>>> everyone. it's not true. >>>> >>>> Oh - I see - so no one pumps there brakes, either in accident avoidance >>>> situations or if faced with runaway acceleration. Got it. (I don't >>>> buy it.) >>> >>> abs. that's the reality, like it or not. >> >> Not all cars have ABS. > >they do nowadays. Certainly NOT ALL new cars have ABS - and if I have my choice, I'll buy without. > > >> Were not talking about what people should do. I'm >> saying what many - not just 1 in 100 - *will* do in the situation we are >> talking about which is unexpected acceleration. > >with respect, you are not representative. see above. They may not "pump " the brakes, but they most likely will try the brakes, release, and try again. Second try not nearly as effective as the first. > > >> >>>>> indeed, but i'm pointing out the fact that refutes your supposition - >>>>> typical panicked drivers do not let off the brake pedal. >>>> >>>> That's your theory and your belief. No more or less valid than mine of >>>> the opposite. >>>> >>> >>> you're entitled to your opinion, but preface them as such. "i believe >>> that..." is quite different from the definitive statements you've been >>> making like "the ... will absolutely *not* ... " etc., because it's >>> not true. >> >> I said that about an engine under acceleration not developing enough >> vacuum to give anything close to expected braking power once the initial >> booster charge is depleted. That is a fact. > >but it's not. there is still sufficient vacuum to generate considerable >assist. not as much as ideal, but it's still there. > > >> Therefore I didn't qualify >> it, and I didn't need to. Where I did give opinion, I identified it as >> such. Shall we go thru the math on the 15% vacuum again? > >sure. after we go through the fact that you've never driven a vehicle >without it and thus don't have experience.
From: clare on 8 Mar 2010 19:45 On Mon, 8 Mar 2010 10:28:36 -0000, "David Skelton" <skellyd8758(a)skynospam.com> wrote: > ><clare(a)snyder.on.ca> wrote in message >news:6ha8p5lum13dounlkv19cscf48rhn9rh5c(a)4ax.com... >> On Sun, 7 Mar 2010 11:44:57 -0000, "David Skelton" >> <skellyd8758(a)skynospam.com> wrote: >> >>>We have had three cars (one made in 1997, the second in 2002 and the >>>third >>>in 2004) that sometimes used to open the throttle on the 'over run', >>>possibly to reduce emissions. >>> >>>It was unnerving approaching junctions. >>> >>>All three had mechanical throttle cables, but also motors built into the >>>throttle body to drive the throttle plate open. >>> >>>Two were Fords, the other was a Daewoo with a Suzuki engine. >>> >>>Best wishes >>> >>>David >>> >>> >>> >>>--- news://freenews.netfront.net/ - complaints: news(a)netfront.net --- >> Virtually ALL port injected engines have an electrically operated >> "idle speed control" or "air bypass" valve that bypasses air past the >> throttle valve for several purposes. It is uded to raise (or maintain) >> idle speed when AC is operated, headlights are turned on, or power >> steering is used at idle, and it is used to prevent abrupt throttle >> closure on decel for emission reasons. >> Some older vehicles used an "idle up" solenoid for the same purpose, >> while others had an "anti-diesel" solenoid to close the throttle >> completely when the ignition was turned off. Other older vehicles used >> a "dash pot" or vacuum idle control to do some of the same. >> >> Vehicles with Drive By Wire, in large part, eliminate the ISC system - >> which, by the way, is one of the more problem prone subsystems on most >> fuel injected vehicles of the last 20 years or so. > >All three had the "air bypass" valve too. > >I do not know what you mean with "ISC system". Idle Speed Control > >BTW, I have known some discreet electronic components that have failed due >to being used too near the maximun demand for too long, would you not >consider that to be 'wearing out' ?? > They fail from overheating, generally - and then USUALY from being under-spec'ed. Capacitors have a finite life - but using a 135C rated cap instead of an 85C rated cap makes it last WAY longer. Something like double for every 5 degrees below spec, and half for every 5 above. Not 100% sure of the number - but very close to that from what I remember. And that is for aluminum electrolytics. Solid tantalum and dry Mylar caps last virtually forever if not run way over the rated voltage. Any discrete component run too close to the limit in a vehicle control system constitutes BAD engineering. Virtually all automotive electronics spec 135C rated parts, ar at the VERY minimum, 105C. Commercial grade is 85C, and they fail in personal computers a lot faster than the higher grade 105s. >Best wishes > >David > > > >--- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
From: clare on 8 Mar 2010 19:47 On Mon, 08 Mar 2010 06:14:04 -0500, Bill Putney <bptn(a)kinez.net> wrote: >clare(a)snyder.on.ca wrote: >> On Sun, 07 Mar 2010 18:29:44 -0500, Bill Putney <bptn(a)kinez.net> > >>> Actually, after some thought, I can see how it might be done with a >>> single pot: Pot wiper gets tied to ground, and you run constant current >>> into each end terminal. The voltages read at the two end terminals will >>> be inverse of each other (as wiper is moved in one direction, voltage of >>> one end terminal goes from 0 to R x I, voltage of the other end goes in >>> the opposite direction). >>> >>> Not saying that the designers would have realized that it could be done >>> like that, but that's the only way I could think of using a single pot. > >> That works too. > >But my way violates the unacceptable ground on an analog input that you >pointed out. Your method is better. > >BUT - you wouldn't even have to raise the ref and its ground. Kind of >combine our two methods: Tie the wiper to the ref. voltage (gets rid of >the ground issue), and put a constant current source (sinking) on both >ends. Scale your constant current and size your pot. such that when the >wiper is pegged to one end (and reading 5 volts), the voltage on the >other end is, say, 1 volt. That could be done with a nominal 8 mA >current source and 500 ohm pot, as an example. The two ends would range >between 1 and 5 volts (nominal), and be inverse of each other. One >check the ECM could do is verify that the two voltages at any moment in >time add up to 6 volts. Quite pssibly how they do it - I was just showing a "simple" example.
From: clare on 8 Mar 2010 19:55
On Mon, 08 Mar 2010 09:10:29 -0500, News <News(a)Group.Name> wrote: >http://www.independent.co.uk/news/uk/home-news/ice-probable-cause-of-boeing-777-crash-1893650.html > > > >DAS wrote: >> "I looked it up". >> >> Could one or both of you provide a URL for us to follow? >> >> Gelling -- not "jelling"... :-) -- or ice formation... would like to read >> up, as I was under the impression from the brief reports I heard on the >> general news that it was diesel gelling, but that might just have been my >> dodgy memory... >> Both Jelling and Gelling are correct english usage. Jell- to become clear, substantial, or definite; crystallize: The plan began to jell once we all met to discuss it. –verb (used with object). 3. to cause to jell. ... >> DAS >> >> To reply directly replace 'nospam' with 'schmetterling' >> -- >> "News" <News(a)Groups.Name> wrote in message >> news:pKSdnRReuqPLGQnWnZ2dnUVZ_rOdnZ2d(a)speakeasy.net... >>> clare(a)snyder.on.ca wrote: >>>> On Sun, 07 Mar 2010 18:05:07 -0500, News <News(a)Groups.Name> wrote: >>>> >>>>> clare(a)snyder.on.ca wrote: >>>>>> On Sun, 7 Mar 2010 11:10:20 -0800, "theref" <theref(a)seanet.com> wrote: >>>>>> >>>>>>> "Grumpy AuContraire" <GrumpyOne(a)GrumpyvilleNOT.com> wrote in message >>>>>>> news:99adnZJAetdSdQ7WnZ2dnUVZ_qidnZ2d(a)giganews.com... >>>>>>>> bjn wrote: >>>>>>>>> On Sat, 06 Mar 2010 10:38:19 -0500, Bill Putney <bptn(a)kinez.net> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> jim beam wrote: >>>>>>>>>>> if you buy all this fear-mongering idiocy that electronic throttle >>>>>>>>>>> is a problem, and that brakes, transmissions and ignition kill >>>>>>>>>>> switches can all simultaneously fail causing a driver to lose >>>>>>>>>>> control, it might be worth auto manufacturers of all stripes to >>>>>>>>>>> adopt a slightly different implementation of electronic throttle >>>>>>>>>>> [e.t.] - if not for mechanical reasons, but to shut the idiots >>>>>>>>>>> up... >>>>>>>>>> The lawyers, politicians, and news media can convince the public of >>>>>>>>>> the impossible (failure even a totally fail safe system) any time >>>>>>>>>> they decide to do it depending on political or monetary motivation. >>>>>>>>>> IOW - the people and companies who do a good job of designing are >>>>>>>>>> going to get punished anyway (unless they know how to play the game >>>>>>>>>> in a corrupt system). There are people in our society whose life >>>>>>>>>> goal is to make sure that that happens. >>>>>>>>> The problem is that now lawyers, politicians and news media are >>>>>>>>> driving (no >>>>>>>>> pun intended) solution. The way I see them talking, cars will wind >>>>>>>>> up with >>>>>>>>> a fail-safe throttle that is more fail-safe than the controls of a >>>>>>>>> jumbo >>>>>>>>> passenger jet. >>>>>>>>> >>>>>>>> I'm not sure about this but for sure... The causes you cite >>>>>>>> certainly contributed in getting to where we're at! >>>>>>>> >>>>>>>> Oh, don't forget that little incident when a B-777's engines went to >>>>>>>> idle about a minute before touch down at Heathrow about a year ago. >>>>>>>> Aircraft was totaled but there were no major injuries. >>>>>>>> >>>>>>>> Cause has been assessed to software/computer glitch. >>>>>>>> >>>>>>>> JT >>>>>>> I believe that was traced to icing in the fuel system. SOP now is to >>>>>>> cycle fuel after prolonged low temp at altitude. >>>>>> Icing on a JET????????? >>>>>> Don't think so. >>>>> Absolutely. Determined to be cause of BA 777 landing short at Heathrow. >>>> OK - I looked it up. Technically this was fuel jelling - common with >>>> diesel fuel in arctic conditions. In the case of the Rolls turbines, >>>> it was a design fault in the fuel pre-heater unit which resulted in a >>>> mandatory replacement with a redesigned heat exchanger. >>>> >>>> Different than the carb icing on a prop plane. >>> It was ice in the fuel blocking the pre-heater, not fuel jelling. Get it >>> straight. >> >> |