I've been doing a bit of research on the L210 gearbox, as I think they're a fair bit lighter than the L110 (450H). I have a new project car coming soon that the LS300H transmission might just suit nicely.
sfk wrote: ↑Sun Jun 07, 2020 7:43 pm
I'm pretty sure the bearings depend on oil circulated by at least 1 of the oil pumps operating. In addition to cooling and actuation of the final output planetary clutch packs.
Interesting idea though. Could reduce a lot of bulk and eliminate the diameter of the bell housing. But you might want to look at the version of this gearbox in the Lexus IS instead. It's similar except doesn't have the 2stage final output. It's called the L210 (as opposed to the L110 in the GS)
I found this online...
The new transmission contains two sets of planetary gears, two electric motors/generators mounted end-to-end in line with the vehicle tail shaft (MG1 and MG2), a hydraulic control system for the planetary gears, an oil pump to generate hydraulic pressure when the petrol engine is stopped, and a cooling system for the electric motors.
The component layout - beginning with the input shaft and working rearward - is a damper to reduce NVH (Noise, Vibration and Harshness), MG1, the first set of planetary gears, MG2, the second set of planetary gears and the output shaft.
MG1 acts mainly as a generator and also as the starter motor for the petrol engine.
MG2 is primarily the electric drive motor, but also acts as a generator during regenerative braking.
The first planetary gear set acts as a power-split device to divide petrol-engine power between driving the rear wheels and MG1.
The second planetary gear set acts as a two-stage motor speed reduction device, allowing a reduction in the size of the electric-drive motor while still achieving impressive initial acceleration.
I have been thinking more about this gearbox too as an option. My only reservation is whether it would be suitable for highway cruising solely in EV mode without the 2-stage final output gearing that the L110 has. Surely it can operate at that speed as it is fixed in relation to the output shaft RPM. And evidently the gearbox on the whole can operate at highway speeds. Just a question of whether it will be sufficient with just the electric motors operating?
wovenrovings wrote: ↑Sun Sep 06, 2020 6:21 am
So I read it to mean that the Is300h gearbox is 2 speed like the gs450h.
That's what the original text seemed to imply, but other Lexus sources confirm it's a two step reduction, not a two speed. To make it work, I would have needed to adopt the ~2.7:1 diff ratio and that wasn't going to happed without more modification of the Lotus rear end than I want to get involved with.
sfk wrote: ↑Sat Sep 12, 2020 9:22 pm
Does that mean with the input shaft locked MG1 would be spinning about 2x 14,000rpm?
No. The front planet assembly connects directly to the output shaft, which means its still very likely -2.6:1 like all the previous generations. This is still a guess though, as there isn’t much material available on the L210.
Everything I've read indicates the L210 is the same as the L110 minus the 2 stage final output housing on the rear.
This means if the ICE input shaft is locked to the housing in order to run as a pure EV using both MG1 & MG2 to generate torque, MG1 will be spinning approx 2.6 times faster than MG2.
MG2 might have a rev limit of 14,000 but will never be able to reach that speed without MG1 bearings flying to pieces.
The way around this is to weld up the planetary gears to lock the MG1 & MG2 together, but is more permanently destructive of course.
Jack Bauer wrote: ↑Sun Sep 13, 2020 10:17 am
You would need to take the weld route due to no external 12v oil pump.
So what would happen to the oil pressure when you come to a stop?
I guess nothing is moving so lubrication wouldn't be super important until you get going again.
With the planetary gear welded it would effectively be just be a straight shaft motor?
Jack Bauer wrote: ↑Sun Sep 13, 2020 10:17 am
You would need to take the weld route due to no external 12v oil pump.
So what would happen to the oil pressure when you come to a stop?
I guess nothing is moving so lubrication wouldn't be super important until you get going again.
With the planetary gear welded it would effectively be just be a straight shaft motor?
For MG1, yes. MG2 would still have 3.33 reduction.
Jack Bauer wrote: ↑Sun Sep 13, 2020 10:17 am
You would need to take the weld route due to no external 12v oil pump.
So what would happen to the oil pressure when you come to a stop?
I guess nothing is moving so lubrication wouldn't be super important until you get going again.
With the planetary gear welded it would effectively be just be a straight shaft motor?
The pump is only needed for bushing lubrication and cooling. No longer needed for applying clutch packs.
Jack Bauer wrote: ↑Sun Sep 13, 2020 10:17 am
You would need to take the weld route due to no external 12v oil pump.
You could always get creative. Remove the mechanical pump, plug the hole (drill/tap a passage, or possibly plug with epoxy) and plumb in an external electric pump. Then you can keep the 2.6:1 reduction for the additional torque/power.
One of these has landed in my garage. At least, I hope that's what it is. It was listed as from a 2015 GS300h.
Also came with the damper which will come in very handy if I go the input shaft locking route.
I guess if the ICE is turning the oil pump, then I need to open up the MG1/bell housing end to take a look in there. Plus check out how the planetary gears work up that end.
Lexus-tech suggests that the oil seal around the ICE input shaft needs to be replaced if it's removed, but maybe if you're removing the whole bell housing you don't actually need to pop the seal out.
FYI, it won’t take much of an oil pump since there are no clutch packs. It only needs lube flow (for all the bushings/bearings). I suspect 15psi and 1GPM should be plenty.
A little earlier I took the MG1 end (bell housing) off of my L210. It was actually very straightforward. The only tricky (messy) part was that you have to take the oil pan off to access three of the bolts.
Everything is the same as the GS450h CVT as far as I can tell from looking at the pics in the OSTI doc, except, that the ring gear has teeth on the outside and there is a second gear attached to the oil pump which is driven by the ring gear.
So, it looks like MG1 or the ICE can drive the oil pump. Those little gears on the oil pump have some sort of one-way mechanism. They only catch going forwards (counter-clockwise in that pic).
I took a quick little video to demonstrate as well.
So, I want to check (and re-check) everything, but, it looks like you could use this CVT in the same way as the GS540h one. Lock the input shaft. MG1 and MG2 will both drive the oil pump. Or, if you want to just use MG2, that will work as well.
MG1 will spin backwards if you lock the input shaft. When you do this does the one way clutch spin the oil pump? Check the output shaft to make sure you are spinning the correct direction.
slow67 wrote: ↑Thu Oct 01, 2020 12:19 am
MG1 will spin backwards if you lock the input shaft. When you do this does the one way clutch spin the oil pump? Check the output shaft to make sure you are spinning the correct direction.
Yep, if I spin MG2 (by turning the output shaft) clockwise (looking at it from the input shaft end) and hold the input shaft still, MG1 spins counter-clockwise. And yes, the oil pump still turns, because the MG2 oil pump gear is still turning in the correct direction. Note the little red mark I put on the MG1 gear.
Here's some detail on the clutches on the oil gears so you can see how they work.
So, I've been puzzling through this a little more today to make sure I'm not being dense. When the ICE turns the input shaft (clockwise), then the MG1 gear also turns clockwise (at a higher speed).
When the ICE is turning MG1 clockwise it's acting as a generator. So I guess clockwise is backwards for MG1.
Then I asked myself, if I want MG1 to contribute to traction, which way do I need to spin it? So, I pulled the ring gear out a bit to make it easier to turn. Then turned the MG1 gear. The test here is backwards as I want the ring gear to turn clockwise, but you get the idea. This confirms that counter-clockwise is forward for MG1 and I want to spin MG1 counter-clockwise to have it contribute to traction.
So, the only remaining concern is the speed that MG1 will end up spinning - as others have noted - when the input shaft is locked. I'll try and get a rough measure of the ratio between MG1 and MG2 when the input shaft is locked tomorrow.
The alternative is to not lock the input shaft and do the Prius transaxle weld job on the planet carrier. Then MG1 and MG2 would be locked together and spin at the same speed. But I think I would do some bench testing before doing that. Plus, you'd have to spin MG1 backwards if you do the weld job.