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Automated Manual with Assist clutch
Posted: 25 Jun 2021, 07:11
by NL_Fer
Browsing transmissions I found this design. It is a 5-speed automated manual transmission, but it replaced the 5th gear syncronizer with an assist clutch. The benefit is to prevent power interruption as follows:
When the transmission is in 1st gear and wants to upshift, the assist clutch is engaged and torque starts to transfer via the 5th gear. When the 1st gear transfers zero torque, it can be shifted to 2nd gear and the assist clutch disengages the 5th to resume torque transfer via the 2nd gear.
So the 5th is only engaged briefly to assist en smoothen the upshift and a clever and compact way to improve the automated manual.
Did anyone see this technology in a real roadcar? If not, why not? It looks simple and great for lowcost aumtomatic cars.
https://www.hitachi.com/rev/pdf/2004/r2004_04_103_3.pdf
https://core.ac.uk/download/pdf/11414743.pdf
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 13:09
by Big Tea
NL_Fer wrote: ↑25 Jun 2021, 07:11
Browsing transmissions I found this design. It is a 5-speed automated manual transmission, but it replaced the 5th gear syncronizer with an assist clutch. The benefit is to prevent power interruption as follows:
When the transmission is in 1st gear and wants to upshift, the assist clutch is engaged and torque starts to transfer via the 5th gear. When the 1st gear transfers zero torque, it can be shifted to 2nd gear and the assist clutch disengages the 5th to resume torque transfer via the 2nd gear.
So the 5th is only engaged briefly to assist en smoothen the upshift and a clever and compact way to improve the automated manual.
Did anyone see this technology in a real roadcar? If not, why not? It looks simple and great for lowcost aumtomatic cars.
https://www.hitachi.com/rev/pdf/2004/r2004_04_103_3.pdf
https://core.ac.uk/download/pdf/11414743.pdf
Did Citroen not use something similar? dont recall the car, posibly Diane?
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 13:15
by Just_a_fan
Big Tea wrote: ↑25 Jun 2021, 13:09
NL_Fer wrote: ↑25 Jun 2021, 07:11
Browsing transmissions I found this design. It is a 5-speed automated manual transmission, but it replaced the 5th gear syncronizer with an assist clutch. The benefit is to prevent power interruption as follows:
When the transmission is in 1st gear and wants to upshift, the assist clutch is engaged and torque starts to transfer via the 5th gear. When the 1st gear transfers zero torque, it can be shifted to 2nd gear and the assist clutch disengages the 5th to resume torque transfer via the 2nd gear.
So the 5th is only engaged briefly to assist en smoothen the upshift and a clever and compact way to improve the automated manual.
Did anyone see this technology in a real roadcar? If not, why not? It looks simple and great for lowcost aumtomatic cars.
https://www.hitachi.com/rev/pdf/2004/r2004_04_103_3.pdf
https://core.ac.uk/download/pdf/11414743.pdf
Did Citroen not use something similar? dont recall the car, posibly Diane?
That had a centrifugal clutch as an anti-stall device, I think.
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 13:18
by Big Tea
Just_a_fan wrote: ↑25 Jun 2021, 13:15
Big Tea wrote: ↑25 Jun 2021, 13:09
NL_Fer wrote: ↑25 Jun 2021, 07:11
Browsing transmissions I found this design. It is a 5-speed automated manual transmission, but it replaced the 5th gear syncronizer with an assist clutch. The benefit is to prevent power interruption as follows:
When the transmission is in 1st gear and wants to upshift, the assist clutch is engaged and torque starts to transfer via the 5th gear. When the 1st gear transfers zero torque, it can be shifted to 2nd gear and the assist clutch disengages the 5th to resume torque transfer via the 2nd gear.
So the 5th is only engaged briefly to assist en smoothen the upshift and a clever and compact way to improve the automated manual.
Did anyone see this technology in a real roadcar? If not, why not? It looks simple and great for lowcost aumtomatic cars.
https://www.hitachi.com/rev/pdf/2004/r2004_04_103_3.pdf
https://core.ac.uk/download/pdf/11414743.pdf
Did Citroen not use something similar? dont recall the car, posibly Diane?
That had a centrifugal clutch as an anti-stall device, I think.
I thought it did did something like the Rover freewheel? but it was many years ago so I am probably mistaken
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 13:19
by Just_a_fan
Big Tea wrote: ↑25 Jun 2021, 13:18
Just_a_fan wrote: ↑25 Jun 2021, 13:15
Big Tea wrote: ↑25 Jun 2021, 13:09
Did Citroen not use something similar? dont recall the car, posibly Diane?
That had a centrifugal clutch as an anti-stall device, I think.
I thought it did did something like the Rover freewheel? but it was many years ago so I am probably mistaken
Could have. As you say, it was a long time ago.
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 13:22
by Big Tea
Just_a_fan wrote: ↑25 Jun 2021, 13:19
Big Tea wrote: ↑25 Jun 2021, 13:18
Just_a_fan wrote: ↑25 Jun 2021, 13:15
That had a centrifugal clutch as an anti-stall device, I think.
I thought it did did something like the Rover freewheel? but it was many years ago so I am probably mistaken
Could have. As you say, it was a long time ago.
After more thought, I think you are correct and I mis-remeber.
BTW, early automated manuals were better than later ones as the system included a 'throttle blip' which was ruled 'un eco friendly' so removed.
Re: Automated Manual with Assist clutch
Posted: 25 Jun 2021, 18:43
by NL_Fer
Throttle blip assist the downshift, it even helps during manual downshifts and clutch disengaged.
This assist clutch is improve the upshift, because often an automated manual upshift is perceived as someone pulling the handbrake between shifts. With assist clutch the torque transfer between engine and wheels is not interrupted during shifting and upshift should be smoother.
Re: Automated Manual with Assist clutch
Posted: 26 Jun 2021, 08:18
by etusch
I think once you use a second clutch it is better the make it dct anymore. This maybe why it didn't wide prefered.
Single clutch automateds are generally bad at lower gears. I have a civic with i-shift a.t. transmission. it is bad at shifting from 1 to 2 and a bit vibrating when car is stationary and 1st gear selected. Another thing is; if battery empty but engine is running then no gear change. Gear selector only powered by battery.
If you want to do it cheaper what I will suggest is not good but If you want to do a decent one it can work. It is just a mild hybrid. when it starts to shift especially at lower gears e.m. will deploy to keep momentum. maybe you can omit first gear by e.m. help unless uphill start.
Re: Automated Manual with Assist clutch
Posted: 26 Jun 2021, 09:52
by Tzk
NL_Fer wrote: ↑25 Jun 2021, 07:11
Did anyone see this technology in a real roadcar? If not, why not? It looks simple and great for lowcost automatic cars.
If i got this right, then this additional clutch will help with engine braking during upshifts and transfer some torque from the engine to the output shaft during the shift, making it (almost) seamless. But you'd still need a regular clutch to fully stop. So this only helps with upshifts, but you can't drive it like a fully automatic (two pedals) transmission. And this is where i think the issue is. If you want a regular automatic transmission, then you'd go for a converter gearbox or a dual-clutch setup (DCT). And in motorsports, you'd use a sequential transmission with throttle-blip and spark-cut for up/downshifts.
So my guess is that this system just too complex and expensive for the benefit it has. At least on a roadcar.