What did we learn from the Chief Engineer?

[john1701a]

"Two-Speed" seems to be the most appropriate label I've encountered for the design/behavior. It avoids the craziness associated with Two-Mode while indicating that there is a second something available.

Anyone hear of an official identifier?

.

[windstrings]

Originally Posted by Rae Vynn

Oh, dear. What is the chief engineer's name? Please? I'm labeling photos...

Don't forget Rae, you also have to say his name clearly three times within 5 seconds or you are not worthy!

[qbee42]

Originally Posted by HTMLSpinnr

I didn't get "2 speed" from the presentation, just that we saw a planetary reduction gear on MG2. Anyone else specifically see/hear otherwise or is it speculation?

I believe it is a fixed planetary gear. I suppose it could be a two-speed planetary gear, but then you need brake bands or clutches, and you start down the path to GM's dual-mode system.

Tom

[Rae Vynn]

Originally Posted by windstrings

Don't forget Rae, you also have to say his name clearly three times within 5 seconds or you are not worthy!

I love you too.

[ken1784]

Hi all,
Let me clarify about reduction gears.

The NHW10/NHW11/NHW20 Priuses have low-speed/high-torque MG2 and the ring gear is driven by the MG2 directly, no reduction gear.

The RX400h/Highlander/Camry have high-speed/low-torque MG2 and the ring gear is driven by the MG2 through reduction gear (single stage).

The GS450h/LS600h/2010 Prius are designed to cover wide range of speed more efficiently, then the ring gear is now driven by the MG2 through two-stage reduction gear.

TOYOTA: Company > Technology

Ken@Japan

[Tideland Prius]

Originally Posted by ken1784

Hi all,
Let me clarify about reduction gears.

The NHW10/NHW11/NHW20 Priuses have low-speed/high-torque MG2 and the ring gear is driven by the MG2 directly, no reduction gear.

The RX400h/Highlander/Camry have high-speed/low-torque MG2 and the ring gear is driven by the MG2 through reduction gear (single stage).

The GS450h/LS600h/2010 Prius are designed to cover wide range of speed more efficiently, then the ring gear is now driven by the MG2 through two-stage reduction gear.

TOYOTA: Company > Technology

Ken@Japan

hmm....

TOYOTA: Company > Technology

[bedrock8x]

The HSDII for the TCH has a second planetary gear set for MG2 speed reduction. The ratio is 2.6:1 and single speed only.

I believe the G3 uses the same system.

Originally Posted by miscrms

I've never studied the Camry/HH/Lexus system, but here's the kind of thing I remember (from john1701a's blog)

"11-30-2007 Multi-Stage Hybrid. Camry-Hybrid differs from Prius by having a second PSD. The purpose is to enable delivery of a second speed, much like gearing"

I thought I had heard several indications that the new Prius system was essentially the same, so I guess I assumed that meant effectively two-speeds. Not sure if that was a correct assumption or not.

Rob

[ken1784]

Originally Posted by bedrock8x

The HSDII for the TCH has a second planetary gear set for MG2 speed reduction. The ratio is 2.6:1 and single speed only.

I believe the G3 uses the same system.

Japanese press clearly says 2010 Prius has two-stage reduction gear.
2010 Prius at Detroit show

Ken@Japan

[jprates]

Originally Posted by ken1784

Hi all,
Let me clarify about reduction gears.

The NHW10/NHW11/NHW20 Priuses have low-speed/high-torque MG2 and the ring gear is driven by the MG2 directly, no reduction gear.

The RX400h/Highlander/Camry have high-speed/low-torque MG2 and the ring gear is driven by the MG2 through reduction gear (single stage).

The GS450h/LS600h/2010 Prius are designed to cover wide range of speed more efficiently, then the ring gear is now driven by the MG2 through two-stage reduction gear.

TOYOTA: Company > Technology

Ken@Japan

Thank you Ken.
Can you provide for a better link where a nice diagram of the GS450h/LS600h system is found? Anyone?
I would like to understand what are the connections, what spins with what, and that page that Ken provided at Toyota does not show that.

P.S. - Ken I have sent you a private message some days ago, can you please check it? Thanks.

[qbee42]

Originally Posted by ken1784

Japanese press clearly says 2010 Prius has two-stage reduction gear.
2010 Prius at Detroit show

Ken@Japan

Interesting, Ken. Thank you for the information. This begs several other questions:

1) How is gearing shifted between the two ratios?

2) Will we be able to detect the shift, as in some sort of shift shock?

3) Will the shifting mechanism reduce the overall reliability of the HSD?

I can take a guess, and that's all this is:

1) I imagine they are using a planetary gear system where one section freewheels or is locked depending on the ratio.

2) Shift shock should be minimal, since we are dealing with a fast electric motor, but I'm going to guess that we will be able to detect it. If we can't feel it, then they might be using some sort of smooth braking system on the planetary gear; perhaps an electromechanical lock.

3) More parts, more mechanical things to break. I don't suppose it's a big hit, given Toyota's track record, but added complexity always concerns me. That's one of the things I like about the original HSD - it's so darned simple.

Tom