Talk:Hybrid Synergy Drive

message: At the end of the article schematics of the drive are given showing what connects to what. The Camry hybrid does not conform to any of these schematics. In particular it uses two gears and the R gears are connected and the output comes from the R gear. The motor goes into S on the second gear. C on the second gear is held still. See http://www.osti.gov/bridge/servlets/purl/922327-5ktfCi/922327.PDF.
I agree with other peoples comments that for many people a definition of S, C, and R would be good.
Hlovatt (talk) 04:54, 8 January 2009 (UTC)
thread_title: Schematics 

message: I'm confused over the figures illustrating the HSD.  None of the figures have legends.  What do the different labels mean? (70.229.84.73 21:46, 10 April 2007 (UTC)
thread_title:  Figures 

message: The article states:  "Reverse gear: There is no reverse gear as in a conventional gearbox: the computer feeds negative voltage to MG2, applying negative torque to the wheels."
Both MG1 and MG2 are permanent magnet AC motors.  They aren't fed "negative voltage" to reverse the torque.  It should read "reverse phase sequence is applied to MG2"  Wefoij (talk) 05:58, 16 January 2008 (UTC)
thread_title:  Reverse Gear 

message: Why use MG-T and MG-S here? Isn't that just being deliberately perverse, given that this article is specifically discussing Toyota's Hybrid Synergy Drive, and they use the names MG1 and MG2? --KJBracey 22:53, 12 November 2005 (UTC)
replies: text: I know what you mean - I can never remember which one is MG1 and which is MG2 myself. But then if Wikipedia used Toyota's  terms throughout the article, it might help us remember :) --KJBracey 16:46, 13 November 2005 (UTC)
thread_title:  MG-T and MG-S? 

message: *Oppose - Hybrid synergy driver article is long enough.  There is a link to the comparison in the HSD article.  If people want to see the car comparison they can click on the link. Daniel.Cardenas 01:53, 21 April 2006 (UTC)
thread_title: Proposal to merge with [[Comparison of Toyota hybrids]]

message: Originally, someone claimed the Escape Hybrid's real-world mileage of 28-32 was "comparable to a conventional four-cylinder SUV such as the Honda CRV". This is B.S. A quick check at fueleconomy.gov shows the CR-V's real-world numbers at 20-24 for all versions (2WD, 4WD, manual, automatic) while the Escape Hybrid averages between 28-34. Probably a case of comparing real-world numbers of one car to EPA estimates of another. The Escape Hybrid is, in fact, the most fuel-efficient SUV in existence, as far as I am aware. Also it incorrectly stated Ford licensed HSD from Toyota, which isn't accurate. Ford developed their own technology but it was nearly identical to HSD so they needed a license from Toyota. CGameProgrammer 17:51, 21 April 2006 (UTC)
thread_title: Comparison of Escape Hybrid with CRV

message: In 2008, the Corolla will also have a HSD hybrid version. .
Moved from page, there is no evidence for this. However, Toyota will eventually release a version, as stated in their model refresh plans. Just a matter of time, but it is speculation at this point and I have moved it here for that reason.--Ng.j 04:27, 19 March 2007 (UTC)
thread_title:  Toyota Corolla Hybrid 

message: "The Toyota Prius has decent, but not sport-car-like, acceleration but has extremely high mileage for a mid sized four-door sedan: 45 mpg (US) is typical of brief city jaunts; 55 mpg is not uncommon, especially for extended drives (which allows the engine to warm up fully). This is noticeably less than twice the fuel efficiency of a similarly equipped four-door sedan with a conventional power train. Not all of the extra efficiency of the Prius is due to the HSD system [...]"
I don't quite understand the bolded sentence.  It seems like it's trying to state the fact that 45city/55highway is less than two times the fuel economy of similar, but conventionally powered, vehicles.  However, saying "noticeably less than twice" has more of a negative connotation to it while "slightly less than twice" seems more neutral.  Isn't average gas mileage for similar, conventional sedans something like 25city/30highway?  That makes a difference of five (5) mpg per category (according to the 2x factor), which doesn't seem worthy of "noticeably".  Does anyone else have thoughts on this or care to do some additional research?
--Godfoster 00:29, 24 May 2007 (UTC)
thread_title:  "Noticeably" less than twice the fuel efficiency of a conventional four-door sedan? 

message: The article states that '... HSD "neutral gear" is achieved by turning the engine off ...'.  I don't think this is accurate, though my knowledge comes from instrumentation and discussion of the NHW11 Prius, before Toyota started calling the powertrain the "HSD".  In that car, the main thing that happens when you put the mode selector in N is that the motor/generator drive electronics is (usually) disabled.  This prevents torque from being applied to the wheels from either the engine or the motor generators themselves.  In some circumstances, the engine will still run, mainly to prevent MG2 MG1 from spinning excessively fast.  This information comes from Toyota's "New Car Features" publication, is accepted in discussion groups and I have personally verified it in an instrumented MY 2001 Prius.  Can anyone state positively that there the HSD operates in a different manner?--GrahamDavies 19:46, 20 August 2007 (UTC)
replies: text: I do not think neutral in the HSD relies on stationary planetary gears. For example, ICE can be run in neutral without sending traction to the wheels. This is a common condition: when ICE has been activated by low SOC before selecting neutral. It is correct that in neutral circuits to all motors are open (to prevent unintended drive to the car). All energy consumed by ICE operation is wasted (as heat) and HB will be drained by car electronics. Running ICE then delivers power only into the path of low resistance: freely spinning / open circuit motors. This gives the same effect as neutral in a conventional car (it pushes easily in either direction, and rolls freely backwards down a slight incline, even with ICE running) but without physically disengaging ICE from the drive train. Quite a neat feature of the HSD planetary gear set. It is worth being clear, as this Wikipedia page is one of the few accessible places that deals with this topic. R Ge B (talk) 02:55, 21 October 2023 (UTC)
thread_title:  Neutral Gear 

message: :Image:Lexus hybrid logo.GIF is being used on this article. I notice the image page specifies that the image is being used under fair use but there is no explanation or rationale as to why its use in this Wikipedia article constitutes fair use. In addition to the boilerplate fair use template, you must also write out on the image description page a specific explanation or rationale for why using this image in each article is consistent with fair use.
Please go to the image description page and edit it to include a fair use rationale. Using one of the templates at Wikipedia:Fair use rationale guideline is an easy way to insure that your image is in compliance with Wikipedia policy, but remember that you must complete the template. Do not simply insert a blank template on an image page.
If there is  other fair use media, consider checking that you have specified the fair use rationale on the other images used on this page.  Note that any fair use images uploaded after 4 May, 2006, and lacking such an explanation will be deleted one week after they have been uploaded, as described on criteria for speedy deletion. If you have any questions please ask them at the Media copyright questions page. Thank you.
BetacommandBot 16:16, 1 October 2007 (UTC)
replies: text: So apparently the problem was that the rationale didn't mention which article the logo was in.  Thanks for fixing that, Addhoc! Issue resolved. Enigma3542002 18:44, 1 October 2007 (UTC)
thread_title: Fair use rationale for Image:Lexus hybrid logo.GIF

message: Could we get a few words about how big the engine is (displacement) and it's horsepower rating, and the the horsepower ratings of the electric motors?  physical dimensions might be interesting too.  —Preceding unsigned comment added by 68.80.95.189 (talk) 00:26, 4 March 2009 (UTC)
thread_title:  Size of engine  and motors? 

message: An image of what appears to be a Toyota Super CVT-i transmission has been included in this article. This is not a component of the HSD, not does the HSD use the variable diameter pulley mechanism that that transmission uses.
The HSD does not actually have a CVT in it at all, it's the power split device that allows the HSD to *act* like a CVT.
Suggest this image should be removed.  —Preceding unsigned comment added by Grs1969 (talk • contribs) 20:08, 29 September 2009 (UTC)
replies: text: Thanks. Although a number of HSD cars use the Super CVT-i, the image is replaced. SynergyStar (talk) 20:21, 29 September 2009 (UTC)
thread_title:  CVT? 

message: But I can personally vouch for the rough behavior described at the end of the Performance section:
:This results in a large decline in performance under certain conditions: an early-model Prius can achieve over 90 mph (140 km/h) on a 6 degree upward slope, but after about 2,000 feet (610 m) of altitude climb the battery is exhausted and the car can only achieve 55–60 mph on the same slope.
I owned two different Priuses(sp?), a 2005 and a 2006 model, which aren't even the very early models. I made a cross country move from the East Coast to Seattle in the first, and another from Seattle back to the East Coast in the second. In both cases, while crossing the Rockies, I had to climb a particularly tough slope at least once, with a car stuffed to the brim with my stuff (probably the equivalent weight of a driver plus 3-4 passengers), and in the East to West move, I had a second passenger to boot. I was going 84 MPH from South Dakota through Montana whenever I could (tires are rated for 85, and I was sticking to 9 miles over the 75 MPH speed limit to limit the damage if I got a ticket). But on a particularly long uphill slope heading west in Wyoming, I got about halfway up the mountain at that speed (using cruise control) before the battery ran out. The instant the battery drained, I dropped to about 50 MPH, and even flooring the accelerator manually I couldn't get above 54-56 MPH until I reached the top of the mountain a couple minutes later. On the way back, I had a similar experience on a long upward slope (not quite a mountain) in Montana, but luckily, the problem only kicked in about 10 seconds from where the slope leveled off and began to go down again, so it wasn't a big issue. In both cases I was traveling in May; the vent was on but not the AC, as the temperature in the mountains was in the high 50s to low 70s range.
Like I said, this isn't a proper citation, but even on a later model Prius (can't say for the very latest model), draining the battery is a possibility and has a *very* noticeable effect on performance. —ShadowRanger (talk|stalk) 17:23, 5 August 2010 (UTC)
thread_title:  Not a citation 

message: From memory the NHW11 motors are rated by Toyota at 33kW and the ICE at 76kW.  The correct values (or values for a newer model) could easily be cited to support an added phrase such as "because the max power drops by a third". 
We don't have those kind of climbs in the UK. My experience is that with both power sources operating it drives like a high spec Golf.  With battery depleted it drives like an old beetle. Shannock9 (talk) 08:53, 6 August 2013 (UTC)
thread_title:  Possible citation 

message: I don't believe this is accurate.  This might be the best speed (not necessarily with respect to thermodynamic efficiency) for an Atkinson Cycle engine in a hybrid, but a typical ICE in a non-hybrid vehicle is more thermodynamically efficient at much higher RPMs-this is from the "Engine Efficiency" article: 
"Engine efficiency peaks in most applications at around 75% of rated engine power, which is also the range of greatest engine torque (e.g. in most modern passenger automobile engines with a redline of about 6,000 RPM, maximum torque is obtained at about 4,500 RPM, and maximum engine power is obtained at about 6,000 RPM). At all other combinations of engine speed and torque, the thermal efficiency is less than this maximum.”
Perhaps the existing sentence is too vague or broad to begin with.
VTEC1981 (talk) 07:04, 16 December 2015 (UTC)
thread_title:  "The most efficient speed (RPM) for an ICE is often around 1500–2000 RPM..." 

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thread_title:  External links modified 

message: I'm confused by this sentence:
:When cruising at high speed, the engine turns more slowly than the wheels but develops more torque than needed. MG2 then runs as a generator to remove the excess engine torque, producing power that is fed to MG1 acting as a motor to increase the wheel speed.
Is MG1 connected to the wheels? I thought MG1 sits between engine and battery/MG2. If this sentence is correct as written, then this mode of operation is missing from the "Power flows" section in the article. AxelBoldt (talk) 18:39, 16 August 2017 (UTC)
thread_title:  Confusing sentence 

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