GS450H Solenoids SL1 SL2

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GS450H Solenoids SL1 SL2

Post by catphish »

What is the function of SL1 and SL2? I have seen conflicting answers to this. Has anyone confirmed with certainty how these interact with the gearing, and how they should be used to select high and low ratio.

Also, what checks should be done (PB1 / PB2?) should be done before actuating them?

I have my own ideas based on the diagrams I've seen, and I know it's been asked before, but I haven't been able to find a definitive answer.
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Re: GS450H Solenoids SL1 SL2

Post by xp677 »

This is covered in the documents from ORNL on the LS600h unit:

https://www.osti.gov/servlets/purl/947393

The brakes actuated by SL1 and SL2 are shown on the attached diagram.

SP is for line pressure control and is modulated.
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gs450h mech diagram.PNG
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

xp677 wrote: Mon Dec 06, 2021 1:43 pm The brakes actuated by SL1 and SL2 are shown on the attached diagram.
Thank you, this appears to be the correct answer, but I'm afraid to say my knowledge of gearboxes is insufficient to understand it. Would you be able to explain like I'm 5 what will actually happen in each of the 4 cases:

* Both brakes disengaged
* B1 engaged
* B2 engaged
* Both brakes engaged
xp677 wrote: Mon Dec 06, 2021 1:43 pm SP is for line pressure control and is modulated.
This part I think I understand, but what do each of the sensors, PB1, PB2 and PB3 indicate? I will need to look at regulating pressure using a combination of the electric oil pump speed, and if necessary, SP.
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Re: GS450H Solenoids SL1 SL2

Post by xp677 »

catphish wrote: Mon Dec 06, 2021 4:04 pm
xp677 wrote: Mon Dec 06, 2021 1:43 pm The brakes actuated by SL1 and SL2 are shown on the attached diagram.
Thank you, this appears to be the correct answer, but I'm afraid to say my knowledge of gearboxes is insufficient to understand it. Would you be able to explain like I'm 5 what will actually happen in each of the 4 cases:

* Both brakes disengaged
* B1 engaged
* B2 engaged
* Both brakes engaged
xp677 wrote: Mon Dec 06, 2021 1:43 pm SP is for line pressure control and is modulated.
This part I think I understand, but what do each of the sensors, PB1, PB2 and PB3 indicate? I will need to look at regulating pressure using a combination of the electric oil pump speed, and if necessary, SP.
I have no idea, I never looked into it. I never intended to use the two-speed transmission in the gearbox.

What I do know is that both disengaged is the high gear, and I believe (from reading on here) that both engaged is the low gear.

PB1 2 3 are covered somewhere on this forum already. I believe one of them is used for overall pressure sensing (to ensure there is sufficient pressure) and the other two monitor the status of the clutches. Or something like that.
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

Thanks, I also saw that people were using both disengaged for high ratio, and both engaged for low ratio, but this seems completely contrary to the video and description by Damien here:

I will test myself as soon as I can and post my own results here, but I thought I'd ask if anyone else had a definitive answer first.
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

Today I did a brief test of all 4 solenoid states

Image

PB1 PB2 and PB3 appear to be inverted (low level is active). PB3 is low whenever the oil pump is running, and I am working under the assumption that PB1 and PB2 indicate the state of the two brakes.

Outputting a high level to both SL1 and SL2 seems to be the only combination that engages low ratio (the output shaft becomes much harder to turn by hand), so that state is clear. It also seems apparent that SL1 is inverted, so having both outputs low actually engages B1, whereas having both outputs high engages B2.

However, what remains a mystery to me are the other 2 states. Based on the PB1 / PB2 outputs both appear to disengage both brakes, but why? And why are both indistinguishable from high ratio? Perhaps my hand based torque measurement just isn't good enough.
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Re: GS450H Solenoids SL1 SL2

Post by PatrcioEV-ATX »

catphish wrote: Tue Dec 07, 2021 9:49 pm Today I did a brief test of all 4 solenoid states

Image

PB1 PB2 and PB3 appear to be inverted (low level is active). PB3 is low whenever the oil pump is running, and I am working under the assumption that PB1 and PB2 indicate the state of the two brakes.

Outputting a high level to both SL1 and SL2 seems to be the only combination that engages low ratio (the output shaft becomes much harder to turn by hand), so that state is clear. It also seems apparent that SL1 is inverted, so having both outputs low actually engages B1, whereas having both outputs high engages B2.

However, what remains a mystery to me are the other 2 states. Based on the PB1 / PB2 outputs both appear to disengage both brakes, but why? And why are both indistinguishable from high ratio? Perhaps my hand based torque measurement just isn't good enough.
Is it possible the hybrid system disengages both brakes when running the output shaft purely from engine power?
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

[/quote]
Is it possible the hybrid system disengages both brakes when running the output shaft purely from engine power?
[/quote]

Seems that would only work if system applies resistance torque on MG1 so all (most?) engine torque can pass from blue to green then out the back. I'd assume that in full engine power mode, brake 1 is on, MG1 is providing very heavy power generation resistance which 1. biases engine power out the prop shaft and 2. powers up MG2 to add to prop torque.

Then when cruising, MG1 loosens up providing just enough juice for engine+MG2 to maintain speed and recharge batteries.

Thank you for the opportunity to just make stuff up :)
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

My bench GS450H is now installed in a vehicle, so this question will be on hold until that vehicle has its wheels and batteries installed. Once that's done, I will test the following:
* Using 0/0 as high ratio
* Using 1/1 as low ratio
* Switching between high and low ratio, both directly, and via the intermediate state 1/0 which I *hope* will momentarily disengage both brakes to allow a smoother change.
Any further knowledge always appreciated.
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

catphish wrote: Wed Dec 08, 2021 6:46 pm My bench GS450H is now installed in a vehicle, so this question will be on hold until that vehicle has its wheels and batteries installed. Once that's done, I will test the following:
* Using 0/0 as high ratio
* Using 1/1 as low ratio
* Switching between high and low ratio, both directly, and via the intermediate state 1/0 which I *hope* will momentarily disengage both brakes to allow a smoother change.
Any further knowledge always appreciated.
I'll also do some testing as my vehicle is about 2 weeks from rolling -- getting ready to mount batteries and install new drive shaft.
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Re: GS450H Solenoids SL1 SL2

Post by muehlpower »

xp677 wrote: Mon Dec 06, 2021 1:43 pm This is covered in the documents from ORNL on the LS600h unit:

https://www.osti.gov/servlets/purl/947393

The brakes actuated by SL1 and SL2 are shown on the attached diagram.

SP is for line pressure control and is modulated.
If I interpret the picture correctly, R stands for ringgear, C for carrier and S for sungear. This means when R and S are stationary at the same time, C cannot move, i.e. the output is blocked. If neither R nor S are fixed, the output is free. This would mean that one magnet must be active in order to drive, if not one of the two clutches is NC.
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

muehlpower wrote: Wed Dec 08, 2021 7:22 pm If I interpret the picture correctly, R stands for ringgear, C for carrier and S for sungear. This means when R and S are stationary at the same time, C cannot move, i.e. the output is blocked. If neither R nor S are fixed, the output is free. This would mean that one magnet must be active in order to drive, if not one of the two clutches is NC.
Thank you, this is my interpretation too. I can't explain why, but I can confirm that it's impossible to activate both brakes and lock the output shaft.

What's less clear to me is what happens when both brakes are deactivated. When doing this, I couldn't feel any difference vs high ratio, but hopefully this is still the correct intermediate state for a ratio change.
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Re: GS450H Solenoids SL1 SL2

Post by xp677 »

I think we previously found that both solenoids off is high gear, and both on is low gear.

Since there are no other valid states for the 2-speed transmission, there was no need to do any further investigation.
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

xp677 wrote: Thu Dec 09, 2021 11:17 pm I think we previously found that both solenoids off is high gear, and both on is low gear.
This absolutely appears to be the case. :idea:
xp677 wrote: Thu Dec 09, 2021 11:17 pm Since there are no other valid states for the 2-speed transmission, there was no need to do any further investigation.
This is the part I am questioning. I know nothing about automatic transmissions, so this is guesswork, but I would imagine that having neither brake engaged would be a valid state, useful only during a ratio change to guarantee that there is no period when both brakes are partially engaged, and ensure a smooth transition. I will test this (instantaneous change vs staggered change) when I can, and report back. :?:
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

So I've got my car rolling and testing shifts. What "gear" is the trans in with default code:


digitalWrite(TransSL1,LOW); //turn off at startup
digitalWrite(TransSL2,LOW); //turn off at startup
digitalWrite(TransSP,LOW); //turn off at startup
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

Also, setting either or both TransSLs to HIGH causes clicking sounds in the trans that continue until I switch back to LOW
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

ggeter wrote: Thu Apr 28, 2022 1:21 am So I've got my car rolling and testing shifts. What "gear" is the trans in with default code:


digitalWrite(TransSL1,LOW); //turn off at startup
digitalWrite(TransSL2,LOW); //turn off at startup
digitalWrite(TransSP,LOW); //turn off at startup
May have answered my own question testing last night. This setting appears to be high gear. Good thing -- because the racket those solenoids make when I set them HIGH is not good....
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

ggeter wrote: Thu Apr 28, 2022 5:03 pm May have answered my own question testing last night. This setting appears to be high gear. Good thing -- because the racket those solenoids make when I set them HIGH is not good....
It's well established that leaving all solenoids off is high ratio. The questions that remain in my mind are as follows:

1) Why is the transmission in high ratio when both solenoids are off? According to the available documentation, I'd expect the transmission to be in Neutral when both brakes are disengaged.
2) Is the state of one of the solenoids inverted, so that the default OFF/OFF state is actually engaging one of them?
3) It's claimed that turning on both solenids select low ratio. However, again based on documentation, I'd expect this to be an invalid (and very unpleasant!) state. I believe people who have tried this say that is makes a nasty bang if you do it while the transmission is turning.
4) What is the impact of turning on just just one solenid or the other?
5) Can we achieve a smooth gear change by engaging one at a time, with a short safety period where both are off, or perhaps switching from 0/0 to 1/1 via 0/1 or 1/0 (which would make sense if one is inverted)
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

I've just read back through this thread. It looks like I did do some testing on this, but I had no high voltage available at the time. I concluded that the most likely correct approach is as follows:

* For high hear, leave both outputs SL1 and SL2 low.
* For low gear set both outputs SL1 and SL2 high.

To switch gears, it's not safe to switch both simultaneously while the vehicle is in motion. Therefore my *guess* is that if it's possible to switch gears at all, the correct approach must be to do so via an intermediate state, either SL1 high and SL2 low, or vice versa.

I would therefore propose writing code to do the following:
* Set torque to zero
* Switch one of the solenoids
* Wait a fixed duration
* Switch the other one

Of course, the order of switching, and time period will be subject to testing and tuning, and I could be completely wrong.
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

Maybe it's a failsafe that when oil pressure comes up, the trans is in high gear and the clutches are locked if power is lost to the transmission. Will have to test that. If no 12v to the solenoid connector at cruising speed, will motor begin to freewheel?
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

ggeter wrote: Thu Apr 28, 2022 7:46 pm Maybe it's a failsafe that when oil pressure comes up, the trans is in high gear and the clutches are locked if power is lost to the transmission. Will have to test that. If no 12v to the solenoid connector at cruising speed, will motor begin to freewheel?
I'm quite sure it will default to high gear if power or pressure are lost. I've seen it theorized that this is safety feature. Also, per my speculation above, if B1 is inverted, then no power to the solenoid connector will always mean B1 is engaged. Still guessing a lot though!
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Re: GS450H Solenoids SL1 SL2

Post by PatrcioEV-ATX »

@ggeter - are you sure you have the right components? There was a whole batch of boards that had the wrong components on IC1,3,4,and 7 (mine included) which caused them to work opposite of the code (it's in the VCU discussion thread I believe). I've also had the clicking noise when I set SL1 and SL2 to HIGH and hoped it was just because I still don't have any oil in the transmission. For now, I've completely removed anything in the code that would allow them to go HIGH. I can't recall now if I had that after I changed out the components or not. Also, right now I have the transmission in the car and the inverter on the bench, so I'm unable to do any testing.
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Re: GS450H Solenoids SL1 SL2

Post by ggeter »

Good question. I remember that discussion. Some of the output switches/transistors were wrong? I'm 99% sure I checked mine and all looked good. I honestly don't think I'd be able to go 40-50 mph like I have been in first gear. It's not jumping off the line, so definitely feels like second gear...
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Re: GS450H Solenoids SL1 SL2

Post by xp677 »

catphish wrote: Thu Apr 28, 2022 5:15 pm
ggeter wrote: Thu Apr 28, 2022 5:03 pm May have answered my own question testing last night. This setting appears to be high gear. Good thing -- because the racket those solenoids make when I set them HIGH is not good....
It's well established that leaving all solenoids off is high ratio. The questions that remain in my mind are as follows:

1) Why is the transmission in high ratio when both solenoids are off? According to the available documentation, I'd expect the transmission to be in Neutral when both brakes are disengaged.

So that the car is still drivable in case of a failure of any part of the system.

2) Is the state of one of the solenoids inverted, so that the default OFF/OFF state is actually engaging one of them?

Not electrically, but you may be correct in that one brake is released with fluid pressure rather than engaged by it.

3) It's claimed that turning on both solenids select low ratio. However, again based on documentation, I'd expect this to be an invalid (and very unpleasant!) state. I believe people who have tried this say that is makes a nasty bang if you do it while the transmission is turning.

Try it and see. Somebody has to do it. Enough people have tried that there must be an answer by now.

4) What is the impact of turning on just just one solenid or the other?

No idea, try it on the bench.

5) Can we achieve a smooth gear change by engaging one at a time, with a short safety period where both are off, or perhaps switching from 0/0 to 1/1 via 0/1 or 1/0 (which would make sense if one is inverted)

Yes, probably. They may be modulated as well, who knows.
Answers in bold, sorry if they aren't helpful.

Just to put that age old question to bed....if you spin up MG2 without the oil pump running and with no solenoids plugged in at all, you'll get torque out at the high gear ratio. Anyone who disagrees can just try it out on the bench or in a vehicle.
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Re: GS450H Solenoids SL1 SL2

Post by catphish »

xp677 wrote: Sat May 07, 2022 10:36 pm
catphish wrote: Thu Apr 28, 2022 5:15 pm
ggeter wrote: Thu Apr 28, 2022 5:03 pm May have answered my own question testing last night. This setting appears to be high gear. Good thing -- because the racket those solenoids make when I set them HIGH is not good....
It's well established that leaving all solenoids off is high ratio. The questions that remain in my mind are as follows:

1) Why is the transmission in high ratio when both solenoids are off? According to the available documentation, I'd expect the transmission to be in Neutral when both brakes are disengaged.

So that the car is still drivable in case of a failure of any part of the system.

2) Is the state of one of the solenoids inverted, so that the default OFF/OFF state is actually engaging one of them?

Not electrically, but you may be correct in that one brake is released with fluid pressure rather than engaged by it.

3) It's claimed that turning on both solenids select low ratio. However, again based on documentation, I'd expect this to be an invalid (and very unpleasant!) state. I believe people who have tried this say that is makes a nasty bang if you do it while the transmission is turning.

Try it and see. Somebody has to do it. Enough people have tried that there must be an answer by now.

4) What is the impact of turning on just just one solenid or the other?

No idea, try it on the bench.

5) Can we achieve a smooth gear change by engaging one at a time, with a short safety period where both are off, or perhaps switching from 0/0 to 1/1 via 0/1 or 1/0 (which would make sense if one is inverted)

Yes, probably. They may be modulated as well, who knows.
Answers in bold, sorry if they aren't helpful.

Just to put that age old question to bed....if you spin up MG2 without the oil pump running and with no solenoids plugged in at all, you'll get torque out at the high gear ratio. Anyone who disagrees can just try it out on the bench or in a vehicle.
I've done bench testing without the motors spinning, my results are summarized in the table above. Essentially, this shows that HIGH/HIGH selects low gear, LOW/LOW selects high gear, and the other combinations are a little confusing.

I intend to test with high voltage in a real vehicle on Monday, so I'll be able to gather more data then, and more importantly, test my theory of changing gear by momentarily switching to the (mysterious) HIGH/LOW state. I will report back ASAP.
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