electronic throttle
in [Toyota]
|
Prev: Toyota Provided No Evidence of Testing Electronic Throttle toUS Congress
Next: Increase your penis size and feel better about yourself!!
From: clare on 7 Mar 2010 17:34 On Sun, 07 Mar 2010 07:12:45 GMT, "MasterBlaster" <Nobodys.Home(a)My.Place> wrote: > >"jim beam" wrote: > >> > Jeff Strickland wrote: >> > YOU (probably in a drunken stupor) said it is feasable to use a mechanical >> > linkage to open the throttle, then use the some other means to close it. >> > Sheer stupidity. >> >> then you're not reading what i said or understanding the control principle. > >I think I understand it. Let's see... > >Similar concept to a Quadrajet carburetor's secondary throttle plate? >In that example, the secondary's linkage is connected to the primary's, >and moves when you floor the gas pedal, but if the choke hasn't opened >all the way yet, then the secondary plates are locked, and not permitted to >open, to prevent the engine from bogging or even stalling when cold. > >As above, with your cable/computer hybrid system, flooring the gas pedal will still >allow the spring-loaded linkage to move, but the throttle plate will only follow the >linkage and open *if* the computer thinks it's safe to do so. If the system sees >you're also pushing hard on the brake pedal, or the car is sliding sideways, or the >ABS system kicks in on a slippery road, or the magic eye scans the invisible bar >code on the speed limit sign and decides you're going too fast, it can override the >gas pedal's position and close the throttle, either partially or completely. All you'd >feel is a decrease in power, and more resistance at the gas pedal as the throttle >plate was pulled closed against the "follow-me" spring in the linkage. >Sounds a lot like the "Traction Control" systems already in use on some cars. > "tandem throttle" Where the computer cannot OPEN the throttle unless the cable op throttle is also open, but the computer can close the throttle any time it likes. The computer can also control the opening of the throttle within the confines of the limit established by the cable op throttle.
From: Bill Putney on 7 Mar 2010 17:38 jim beam wrote: > On 03/07/2010 12:42 PM, Bill Putney wrote: > how did you manage before the days of vacuum assist? In spite of my having gotten my driver's license in about 1966 or 67, My family nor I has ever owned a vehicle without power brakes since then. I did however drive someone's car to an airport one time that did not have power brakes - and I must say - I thought something was seriously wrong with the brakes. Later, I even loudly complained to the owner for having me drive their car in such a dangerous condition (they were a family friend). It was explained to me that that was a car without power brakes - and was typical of them. All I have to say is "WOW". >> - the >> engine will likely overcome the brakes in being able to sustain highway >> speeds (and this is before fade comes into the picture). > > fade is a feature of people that don't brake decisively and let the > vehicle speed up again. or defective design/parts. Beating the dead horse, but we're talking about two different things - vacuum depletion and fade. We're going in circles. >> Saying that 63 sq. in. is a big surface area and so even a tiny little >> vacuum will give you huge force means nothing. Fact is the assist force >> on the diaphragm with the very low vacuum under acceleration is less >> than 15% of what it was designed to use under normal stored vacuum >> conditions. > > how did anyone drive a car before the days of vacuum assist? From my one time of driving that car without assist - that's a good question. Stopping distances must have been absolutely awful. >>> you're supposed to apply the brakes and keep them on. only if you >>> release do you lose vacuum. >> >> Right or wrong, many people were taught to pump the brakes. Some people >> will in fact pump the brakes, for any number of reasons. > > some people will hold their foot on the gas believing it to be the brake > too. That's a whole other problem of course. >>> ...again, if that's your experience, i think you're working with >>> something not representative of most vehicles. certainly not anything >>> post 1980. >> >> Nope. Your assumptions are wrong on both counts. > > why? why does my car come to halt when i brake hard at full throttle? > why doesn't yours? No argument if it's a single long application of the brakes. Are we talking about after the brakes are pumped a couple of times after application of throttle? My experiences were on things like an '86 Subaru Turbo wagon, an '88 Cadillac DeVille, '99 Buick Century, and 2 2nd generation Chrysler Concordes - all in tip-top mechanical shape. >>> where is your "theory" that people pump brakes? i saw someone on a >>> freeway in rain in los angles one time, skating along with their >>> brakes locked, car gently rotating, and the look on her face was that >>> of someone trying to break the pedal off she was pushing it so hard. >>> there's no way that person, as an average driver, was going to let off >>> that pedal, and thus, even though she was going to crash, she was not >>> going to lose vacuum. >> >> You keep throwing in scenarios totally different than what we're talking >> about. > > no, i'm pointing out the flaw in the argument. for the argument to be > valid, it has to work universally. otherwise you need to qualify it to > specific circumstances. >> Again - you can't prove your claim that hardly anyone pumps the >> brakes any more than my claim that a lot of people would pump the brakes >> - so from that standpoint, it's what we each want to believe until >> someone presents some hard evidence. Your observations in life are no >> more or no less valid than mine are - so quit belittling mine and >> touting your just as anecdotal observations as more than they are. > > but dude, why do we have abs? it's not because people pump the brakes > because then they'd be unnecessary! Some people were taught and developed a lifelong habit of pumping brakes. >>>> 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. 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. >>> 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. 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? -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
From: clare on 7 Mar 2010 17:40 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.
From: clare on 7 Mar 2010 17:47 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. 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.
From: clare on 7 Mar 2010 17:49
On Sun, 07 Mar 2010 08:39:54 -0800, jim beam <me(a)privacy.net> wrote: >On 03/07/2010 08:13 AM, Bill Putney wrote: >> jim beam wrote: >>> On 03/06/2010 08:36 PM, Bill Putney wrote: >>>> Jeff Strickland wrote: >>>> >>>>> ...We have not explored the interaction of traction control and >>>>> antilock brakes preventing the brakes from stopping a car with a >>>>> throttle intent on being set to the maximum setting. We also have not >>>>> looked at the issue of brake fade that comes from the brakes getting >>>>> hot. If the brakes locked the front tires, the ABS would sense this >>>>> and unlock them. The driver might keep his foot planted firmly on the >>>>> brake pedal which has sunk to the floor, but the car still would not >>>>> stop. The brakes get hot and fade badly, and the car wouldn't even >>>>> slow down... >>>> >>>> Read my previous post. With throttle applied (even partial throttle), >>>> the booster vacuum gets depleted *rapidly*. There is no way to use the >>>> brakes to stop a car with an engine of any power at all with throttle >>>> applied since, with throttle applied, intake vacuum drops to close to >>>> zero. No vacuum = essentially no brakes. Try the experiment I described >>>> in my previous post. >>>> >>> >>> no dude. even with no engine running to replenish vacuum, there is >>> still sufficient vacuum reserve in the booster to apply the brakes >>> full-on three times. unless you have a leak of course, which could >>> also be affecting your experience. >>> >> >> By the second stab, typically brake effectiveness is reduced >> considerably. By third stab - engine overpowers brakes - power assist is >> negligible. No leaks, > >i'll bet you haven't actually tested that. all you know from driving is >that there is sufficient vacuum for the brakes to appear to work ok, >i.e., evacuation rate > leak rate. it's only when leak rate > >evacuation rate that people notice anything. in the mean time, a slow >leak might be sufficient to lose vacuum in 30 seconds or less. I know from many years of working as a mechanic, and years of competition driving, that without constant manifold vacuum, counting on the SECOND stab of the pedal is a gamble. The third stab is guaranteed to disapoint. > > >> multiple cars in perfect condition. >> |