electronic throttle
in [Technical]
|
From: jim beam on 7 Mar 2010 00:58 On 03/06/2010 08:26 PM, Bill Putney wrote: > jim beam wrote: >> On 03/06/2010 11:48 AM, Ed Pawlowski wrote: > >>> ...Emergencies do happen and a driver should be competent enough >>> to shift into neutral. >> >> or stomp the brakes - which are three times more powerful than the >> engine,... > > 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. > > 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. i've experienced that too, one particular time on a major hill in san francisco approaching a busy intersection. yes, it's scary stuff. but when i changed the pads on my civic from after-market to oem, all fade problems disappeared. even fully loaded, repeatedly decelerating from speed. [i learned my "honda oem is best" lesson that way.] > > Also, once the booster is depleted of vacuum during that experiment, the > vacuum charge in the booster will remain depleted until a second or so > after the throttle is released - IOW - deplete it and continue applying > the throttle (again - doesn't have to be anywhere near WOT) for several > seconds. Every once in a while, while still applying the throttle, try > the brakes again. You will not have any effective braking until *after* > you release the throttle. > > I urge anyone who doesn't believe what I claim above to try it before > commenting. i have. my results and comments are as above. -- nomina rutrum rutrum
From: dsi1 on 7 Mar 2010 00:59 On 3/6/2010 5:30 AM, jim beam wrote: > > this would not only address the "potential" for a runaway failure > [although how exactly a computer is supposed to fail such that it won't > switch off, disables brakes, disables transmission select, but still > runs its injection code is something i have never seen explained, even > by the most strident "but it must be the electronics" crowd], but it > would also remove the single most annoying thing i have ever experienced > in any vehicle driving experience: chevy's idiot idea that they need a > multi-second delay between foot pedal movement and e.t movement. anyone > that's ever tried to drive a chevy hhr on a winding mountain road knows > what i mean. I think most technically minded person would tend to agree that it's probably the control electronics. You're wrong in assuming that folks like us would think that unintended acceleration would be accompanied by failure of all the systems you cite. That's absurd. :-) > > y'all can now wait for at least 10 years for arrival, but i throw it out > there for what it's worth. I don't think it's worth as much as you think since it's likely that we'll be using electric motors instead of air pumps to move cars.
From: jim beam on 7 Mar 2010 01:13 On 03/06/2010 09:59 PM, dsi1 wrote: > On 3/6/2010 5:30 AM, jim beam wrote: >> >> this would not only address the "potential" for a runaway failure >> [although how exactly a computer is supposed to fail such that it won't >> switch off, disables brakes, disables transmission select, but still >> runs its injection code is something i have never seen explained, even >> by the most strident "but it must be the electronics" crowd], but it >> would also remove the single most annoying thing i have ever experienced >> in any vehicle driving experience: chevy's idiot idea that they need a >> multi-second delay between foot pedal movement and e.t movement. anyone >> that's ever tried to drive a chevy hhr on a winding mountain road knows >> what i mean. > > I think most technically minded person would tend to agree that it's > probably the control electronics. well, i'm technical, and i know a bit about electronics. and i know electronics can be considerably more reliable than mechanical systems. what i see with this well orchestrated and persistent toyota smear campaign is the "electronics" poop sticking to the fan because it's the "black box" the average shade-tree mechanic knows the least about. nothing scares the proles like "fear of the unknown". > You're wrong in assuming that folks > like us would think that unintended acceleration would be accompanied by > failure of all the systems you cite. That's absurd. :-) sure is! > >> >> y'all can now wait for at least 10 years for arrival, but i throw it out >> there for what it's worth. > > I don't think it's worth as much as you think since it's likely that > we'll be using electric motors instead of air pumps to move cars. maybe, but i doubt it. until you can get 300+ miles out of an electric charge, and re-charge in 10 minutes or less, i see gasoline/diesel remaining with us for a looooong time yet. -- nomina rutrum rutrum
From: dsi1 on 7 Mar 2010 01:15 On 3/6/2010 6:26 PM, Bill Putney wrote: > jim beam wrote: >> On 03/06/2010 11:48 AM, Ed Pawlowski wrote: > >>> ...Emergencies do happen and a driver should be competent enough >>> to shift into neutral. >> >> or stomp the brakes - which are three times more powerful than the >> engine,... > > 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. > > 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. > > Also, once the booster is depleted of vacuum during that experiment, the > vacuum charge in the booster will remain depleted until a second or so > after the throttle is released - IOW - deplete it and continue applying > the throttle (again - doesn't have to be anywhere near WOT) for several > seconds. Every once in a while, while still applying the throttle, try > the brakes again. You will not have any effective braking until *after* > you release the throttle. I certainly believe you. You can get a feel for the amount of reserve vacuum boost on your car by simply repeatedly pressing down on the brakes without starting your engine. If your brakes are working properly, you'll feel the pedal getting firmer until you'll only be able to move the brake pedal a couple of inches of deflection. At that point, you'll have used up all your vacuum reserve. I figure that you should be able to get around 3 stabs at the brakes with mostly full boost. This means you'll only get maybe two chances for full braking after the initial attempt at braking. That's the breaks I guess. :-) > > I urge anyone who doesn't believe what I claim above to try it before > commenting. >
From: MasterBlaster on 7 Mar 2010 02:12
"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. |