Question about planetary gears
11-12-15, 12:46 PM
#1
Question about planetary gears
According to Lexus, the current GS 450h contains a planetary-gear transmission that can switch between two gear ratios. Under what circumstances is the gearing changed?
11-12-15, 07:21 PM
#2
So I believe there is a high-low gear ratio.
From Wikipedia (https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive):
Since this was introduced & implemented starting from the 3GS hybrid, here is a great topic that covers a lot of what you may be curious about: https://www.clublexus.com/forums/hyb...-it-works.html
Keep in mind, the change is planetary-gear transmission is different than electronically changing the throttle mapping (which happens when you shift between the Eco, Normal, and Sport/Sport+ modes).
I'll see if neurocity can add more comments or make any corrections to what I have stated since he's a very knowledgeable member we have here.
~ Im2bz2p345
From Wikipedia (https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive):
Toyota Hybrid Synergy Drive (HSD):
"In 2006 and 2007, a further development of the HSD drivetrain, under the Lexus Hybrid Drive name, was applied on the Lexus GS 450h / LS 600h sedans. This system uses two clutches (or brakes) to switch the second motor's gear ratio to the wheels between a ratio of 3.9 and 1.9, for low and high speed driving regimes respectively. This decreases the power flowing from MG1 to MG2 (or vice versa) during higher speeds. The electrical path is only about 70% efficient, thus decreasing its power flow while increasing the overall performance of the transmission. The second planetary gearset is extended with a second carrier and sun gear to a ravigneaux-type gear with four shafts, two of which can be held still alternatively by a brake/clutch. The GS 450h and LS 600h systems utilized rear-wheel drive and all-wheel drive drivetrains, respectively, and were designed to be more powerful than non-hybrid versions of the same model lines, while providing comparable engine class efficiency."
"In 2006 and 2007, a further development of the HSD drivetrain, under the Lexus Hybrid Drive name, was applied on the Lexus GS 450h / LS 600h sedans. This system uses two clutches (or brakes) to switch the second motor's gear ratio to the wheels between a ratio of 3.9 and 1.9, for low and high speed driving regimes respectively. This decreases the power flowing from MG1 to MG2 (or vice versa) during higher speeds. The electrical path is only about 70% efficient, thus decreasing its power flow while increasing the overall performance of the transmission. The second planetary gearset is extended with a second carrier and sun gear to a ravigneaux-type gear with four shafts, two of which can be held still alternatively by a brake/clutch. The GS 450h and LS 600h systems utilized rear-wheel drive and all-wheel drive drivetrains, respectively, and were designed to be more powerful than non-hybrid versions of the same model lines, while providing comparable engine class efficiency."
Keep in mind, the change is planetary-gear transmission is different than electronically changing the throttle mapping (which happens when you shift between the Eco, Normal, and Sport/Sport+ modes).
I'll see if neurocity can add more comments or make any corrections to what I have stated since he's a very knowledgeable member we have here.
~ Im2bz2p345
11-12-15, 07:42 PM
#4
So I believe there is a high-low gear ratio.
From Wikipedia (https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive):
Since this was introduced & implemented starting from the 3GS hybrid, here is a great topic that covers a lot of what you may be curious about: https://www.clublexus.com/forums/hyb...-it-works.html
Keep in mind, the change is planetary-gear transmission is different than electronically changing the throttle mapping (which happens when you shift between the Eco, Normal, and Sport/Sport+ modes).
I'll see if neurocity can add more comments or make any corrections to what I have stated since he's a very knowledgeable member we have here.
~ Im2bz2p345
From Wikipedia (https://en.wikipedia.org/wiki/Hybrid_Synergy_Drive):
Since this was introduced & implemented starting from the 3GS hybrid, here is a great topic that covers a lot of what you may be curious about: https://www.clublexus.com/forums/hyb...-it-works.html
Keep in mind, the change is planetary-gear transmission is different than electronically changing the throttle mapping (which happens when you shift between the Eco, Normal, and Sport/Sport+ modes).
I'll see if neurocity can add more comments or make any corrections to what I have stated since he's a very knowledgeable member we have here.
~ Im2bz2p345
This guy right here is controlling your car.
11-24-15, 07:52 AM
#5
Hi maurerc,
Just incase you wanted a video showing the same "switch in gearing" in a 4GS hybrid, see below:
The shift in gearing happens at:
1st attempt 0:26
2nd attempt 0:45
Also, I came across a lot more technical information on how exactly the Toyota/Lexus hybrid transmission functions with the electric motors.
http://john1701a.com/prius/documents...lit-Device.pdf
http://www.eahart.com/prius/psd/
Pretty amazing technology. I cannot wait until we have more efficient battery power that doesn't add as much weight, so that the car can be propelled even more with battery power off the line.
~ Im2bz2p345
Just incase you wanted a video showing the same "switch in gearing" in a 4GS hybrid, see below:
The shift in gearing happens at:
1st attempt 0:26
2nd attempt 0:45
Also, I came across a lot more technical information on how exactly the Toyota/Lexus hybrid transmission functions with the electric motors.
http://john1701a.com/prius/documents...lit-Device.pdf
http://www.eahart.com/prius/psd/
Pretty amazing technology. I cannot wait until we have more efficient battery power that doesn't add as much weight, so that the car can be propelled even more with battery power off the line.
~ Im2bz2p345
Last edited by Im2bz2p345; 11-25-15 at 09:07 AM.
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