The 2017 Accord Hybrid is a real challenger to Toyota hybrid cars

Honda's system should have less losses than any PSD type of system. Its MG/1 is a starter and generator, and doesn't need to work with and against the ICE in order to produce variable gear ratios. Being direct drive makes it even simpler mechanically. The motor is the more efficient part of the ICE/motor duo. The efficiency of making electricity is the limiting factor. Which drops at highway speeds, and why the ICE clutches in then.

In a bigger and heavier car, this system comes close to matching the gen3 Prius. The improvements for the gen4 Prius come from improving the ICE efficiency and cutting weight.

 

The Prius Prime operates exactly like a regular gen 4 Prius when the gas engine is running. The one-way clutch in the Prime only plays a role when the gas engine is off. It allows both electric motors to propel the car together by preventing the gas engine from spinning backwards so that MG1 can push against the locked-up engine and all of its power will flow to the ring gear and thus mix with the power from MG2 that drives the wheels.

The Volt and the Malibu use essentially the same new "Voltec 2" hybrid transmission but with some tweaks between their electric motors and the Malibu does not need or contain the Volt's dual motor one-way clutch that effectively acts like the Prime's one-way clutch although it is implemented differently.

The Volt and Malibu have a direct-drive parallel hybrid mode at vehicle speeds above 30 or so mph but it is used only under some conditions.

Unlike the Honda, which uses its parallel direct drive for essentially all highway driving, the Volt and Malibu use a second continuously variable series/parallel mode that mechanically links MG2 and the wheels to MG1 which allows torque from MG2 to mechanically recirculate to the power-split planetary gear. This lowers the amount of electrical power recirculating that would otherwise take place (in a Prius, for example) at highway speeds. It increases the total flow of mechanical power from the gas engine to the wheels at higher vehicle speeds while still allowing variable engine gearing to help keep the engine in its most efficient rpm/torque range.

The Malibu hybrid competes directly against the Accord hybrid and Toyota Camry. While the 2017 Accord is rated as 49/48/47 (city/combined/highway) the 2016 Malibu hybrid is rated as 47/46/46. The 2016 Camry hybrid is rated 43/41/39 and has clearly fallen behind Honda and Chevrolet. I believe the Camry hybrid powertrain is also used in the RAV4 hybrid. I assume a newly updated version of this powertrain will show up within the next year or two.

 

That was my understanding of how Honda's system works at highway speeds. Well, as a split hybrid; some engine power is spinning MG/1 to power MG/2. At lower speeds, it operates as a series hybrid using just the motor to directly drive the wheels like a BEV. Honda says it doesn't have a transmission, because there is no changing of gear ratios in the drive line; they are all fixed.

Toyota's HSD is an eCVT. It varies MG/1 speed and even direction, with that of the ICE in order change the transaxle's effective gear ratio. It could simulate the direct drive of the Accord's system, but so can an ICE car with automatic transmission when the tranny locks up, disengages the torque convertor and directly connect the engine to the drive line.

 

something is not right with honda hybrids. great cars and engineering, but something is not right. let's revisit the 2017 accord hybrid in 2022.

 

Right now the Hyundai IonIQ looks like the car that *might* give Prius some viable competition. Part of the reason you are buying a Prius is (1) high MPG; (2) practical space/ big cargo space hatchback; and (3) low maintenance making it the lowest cost of all USA cars on the road. Topping that is a tall order, but let the games begin.

 

I'll believe it when I see it. I wish I had a dollar for every article like this. All have fallen short.

 

don't forget 20 years track record.

 

every decent hybrid will eat into prius sales. and even some not so decent ones. but gen 4 is designed to go after a new market of non hybrid drivers. i expect a big year, no matter the competition.

 

curious where you guys go to learn all this info on how the hybrid systems work. i don't find much public information. would love to learn more and be able to understand and picture more of waht you're saying.

 

you're looking on youtube? there should be tons of stuff. start with john1701's home page.

 

Graham's Toyota Prius Area

Is a good place to start.

 

What is wrong with Honda's new I-MMD hybrid design? It seems to be the mpg winner between the Camry/Malibu/Accord. It's more powerful than the powertrain used in the Prius Liftback but gets close to the same mpg in a car weighing about 500 pounds more.

Does anyone have specific criticism of the I-MMD performance, NVH, or efficiency under varying conditions?

HSD could not really "simulate" the series mode behavior since most of the engine power inherently flows mechanically in HSD. At higher speeds I suppose HSD could be programmed to hold MG1 still (where it is free-spinning on the Honda) but the engine's fixed gear ratio to the wheels wouldn't necessarily be a good match with Honda's system. I don't know what Honda's fixed ratio is. I plan to figure all this out in detail soon.

One of Honda's claims is that their system has about half of the transmission losses in engine highway mode due to its simplicity and that makes up for other efficiency differences where a Prius-like transaxle might do better.

 

By direct drive I meant how the Accord's traction motor, and when engaged, the ICE, is directly tied to the wheels by a single gear ratio.

My other example of simulating this was an automatic step transmission on an ICE in lock up. When locked up, the engine's output is no longer propelling the car by pushing transmission fluid around in the torque converter, but directly clutched in to the transmission's input shaft. The engine is directly driving the wheels through a single gear ratio. The transmission has other ratios, but shifting isn't done during lock up. The shifts would be harsh, and possibly damaging.

 

i don't know anything about their hybrid design. my criticism is with honda the company.
we have been waiting 20 years for some decent hybrids, and we're still waiting.
now you'll tell me that the accord is available again. great, but have you ever seen so many botched attempts?
see me in 5 - 10 years, when they have consistently produced a winner.

 

you can search many from
hondarandd.jp
or
SAE website

 

It's too expensive...
the MG2 is around 130kw, mg2 is 105KW. comparing with camry hybrid's mg2 104kw, and estimated 70kw MG1
honda once said it can reduce the cost of their motor to near toyota level, but how can they neglect those horse power of motor.

I-MMD has advantage in highway cruising indeed, does it worth the extra cost of motor?

 

search for some national lab's test on accord hybrid, they figured out the gear ratio.
their words are "engine speeds of 2000 rpm and 4000 rpm correlate with a vehicle speed of 66 MPH and 112 MPH"
curiously, 66,112, how can they be 2000 and 4000 rpm.