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Hybrid Vehicles Hybrid Vehicles - Archived Discussions How do Hybrids work? Newbie questions encouraged! 
139 messages, Last post on Aug 02, 2007 at 5:38 PM
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Replying to: otis1 (Jan 27, 2006 7:26 am) You wrote "Hopefully this won't turn into a discussion about Einstein" I second that !! Here's maybe what you are missing in your knowhow. Internal combustion engines typically have a maxx efficiency point around a 38% power loading. Lower power loadings are less efficient because fixed losses predominate. Higher loadings are less efficient because losses proportional to engine speed predominate. A 38% power loading is still too high for just plain cruising at any speed below 65mph. -- Others may wish to know what good this is well.... Prius hypermilers who want to travel efficiently below a steady 42mph can use a pulse and glide technique. They slowly come up to within 42mph in electric mode so the ICE won't have an excuse to start and gradually deplete the battery. This is the glide part of course. Then at around 20% state of charge (SOC) the engine will fire up automatically. The ICE now has two jobs, provide motive power and charge the battery. If the battery is warm it will have full capacity and charge in a few minutes to 90%. This double loading operates the ICE at its most optimum power for a short period which is known as the pulse. The driver monitors the display to know when 90% SOC is reached and will then momentarily slow to encourage the ICE to stop. Then 'feathers' the speed back up to within 42 mph under electric power only to begin the whole glide process over again. I hope this explanation answers some questions for you and helps a bunch more who are new to Prius. Visit john1701a.com for more Prius stuff. As another poster wrote " I can try explain it for you, but I cannot understand it for you". ! T2
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Replying to: toyolla2 (Feb 24, 2006 6:55 pm) What kind of driving can best charge the battery to 8 bars? Should I set the transmission to B instead of P? If I am at 6 bars, I cannot seem to get the battery to continue charging unless it is cold out or I am going down a long hill. Any help will be appreciated. AutocrossTom
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Replying to: autocrosstom (Mar 28, 2006 4:30 pm) Manual Charging With the Ready light on and the gear in P, press the accelerator padel. ICE will start and charge the HV battery Automatic Fast Charging 1. Start the car 2. Put it in Drive 3. Depress both the brake and gas pedal simultaneously to the floor. 4. The car will recognise that you want to charge the battery and move into a special "fast charging" mode. 5. This can take up to 5 minutes depending on the charge state of your battery (you can even get it up to 100% - FULL GREEN) 6. The car will NOT overrev and will adjust the engine speed back as the battery charges. Dennis |
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Replying to: midnightcowboy (Oct 27, 2005 7:47 am) Why? Because that's the basic principle of E-CVT. Yes, that's how HSD transmission works in a nutshell. The ICE make only 82 lbs-ft torque. It does not produce enough twisting power to properly accelerate the Prius. This situation prevents the ICE from making it's maximum power since it can't rev the RPM fast enough (already too hard to twist). So what does it do? The Power Split Device comes to the rescue. It spins the MG1 so fast that it generates electricity. This allows ICE to make maximum (or necessary) power while MG1 steals away that energy. MG1 generating electricity and supplying it to MG2 creates massive (295 lbs-ft) torque -- equivalent of 1st gear. Now, all the power of ICE is going out to the wheel. E-CVT stands for electrically controlled variable transmission. How does it control electrically? Well, it depends on the speed of MG1 -- how much electricity it generates. If you stop the MG1, you loose the control and it can't be variable anymore. You might as well call it E-NCST (Electrically Not Controlled Static Transmission). ---------------------------------------------------- "In my higher math, before calculus of several variables, I thought that 66 was greater than 51." You do not need Calculus for this, just Arithmetic and Common-sense. You are comparing 1.0 liter Insight ICE to 1.5 liter Prius ICE. Why don't you look at the Civic Hybrid 1.3 liter highway 47 mpg? Which is greater? 51 or 47? By looking at the results, Honda's IMA is less efficient because 1.3 liter engine is getting less mpg on the highway than Prius 1.5 liter engine. Prius is even bigger than Civic. ------------------------------------------------------- "Why is the highway mileage of the Prius less than the City mileage while the Insight is higher?" Because Insight simply sux in the City, even though there is less air drag in low speed city driving. Prius is equally good in both City and Highway. The reason Highway mpg is lower is due to air resistance at high speed. PS: I know I am replying to a very old post because no one actually addressed it. Dennis
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Replying to: usbseawolf2000 (Mar 28, 2006 6:54 pm) 
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Replying to: midnightcowboy (Mar 29, 2006 9:31 am) |
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I am looking into buying a HH. I currently have a 4Runner and a preschooler with alot of stuff. Can you tell me anything about the car. How it drives, stops (I read about the breaking problem), anything you feel could be helpful to me. Also if anyone knows of a better car. I want a Hybrid for the green factor and to hopefully save a few pennies. I would like to hear from people who love their car and why. I also want to know what you hate abouy it. Are the cupholders in a good place. I am still a woman and we like to know these trival things. THANK YOU all in advance for any help,ideas.
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Replying to: melski (Jul 26, 2006 7:26 am) You can get tons of feedback on this vehicle in our Toyota Highlander Hybrid discussion. Lots of current owners participate there. |
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Having just recently purchased a Toyota Prius. I find it amazing that when the ICE starts it is so seamless, less noticeable than a typical automatic transmission shift! I was wondering if the ICE internals where always moving with the CVT therefore no spinup time is required?
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Replying to: enrolb (Aug 22, 2006 12:15 pm) The quick answer is for speeds below 42mph you'll find the engine is fully stopped quite often. It is always fully meshed with the drive train same as an auto transmission. However the similarity ends there because there are no slipping clutches or hydraulic torque converters employed here. What there is is just this differential gear that the engine feeds to. A small but powerful servo feeds this differential gear system also. Power takeoff to the wheels is through a third gear. It is this gear which drives directly to the wheel axle with a 4:1 stepdown. If the wheels are turning and the engine is not required then the Prius computers will instruct the small servo to rotate precisely at the right speed so that the crankshaft can remain stationary. But how does it do it is a whole other question ! If you want to know more, first take a look at the line dwg on Post #470 on the Toyota Camry Hybrid board. That top drawing is your car. See the planetary gear in the centre ? Well it's not clear from the drawing, at least not as clear as it could be, but the crankshaft of your engine is connected to the planetary carrier which supports the planet gears which race around the sun. The sun gear itself is driven by a hollow shaft from the smaller servo (if you can call 30kw (42Hp) small ! ) commonly referred to as MG1. Now here's the tricky part. In order for the crankshaft to meet the planet carrier it has to go through the hollow center of MG1 and its shaft and then proceed through to the other side of the side of the planetary assy where it can then join rigidly to the carrier. The third part of a planetary gearbox is the outer ring gear. This is the internal tooth gear the planets run around inside. It also connects directly to MG2, your main 67Hp traction motor. And eventually the wheels as the diagram shows. T2 |
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