"Small" torque converter

[briangmr]

I am looking for a lock-up torque converter to be used on a 1500lb GVW vehicle equipped with a 15HP diesel motor. Ideally, stall would occur at 2000 rpm and lockup at 3000-3500 rpm. Torque multiplication factor is open at this point. I have looked at a number of torque converter manufacturers (and auto OEMs), but have been unable to find anything in this size. Are there any European or oil embargo era vehicles that might have a GVW and low HP diesel motor similar to my application? Any manufacturers offering torque converters for small, low power vehicles?

Thanks!

Brian

 

[Chumley]

Just a guess, but I think that with a 15 hp engine and a 1500 lb. vehicle, you'll find that a torque converter is too inefficient and consumes too much of the available engine power prior to lockup. Most likely, that's why you are having trouble finding a manufacturer that makes what you're looking for. 1:100 power to weight ratio loading is just slightly more than the short term peak power of an olympic class athelete on a bicycle.

We used shaft mounted centrifugal type mechanical clutches in the days when we mounted a 5 hp lawn mower engine on a 250lb go-kart with driver. They can be designed to lock up at almost any RPM above about 1200 and are much less complicated than a fluid coupling but provide no torque multiplication.

Variable ratio open belt drives(CVT's) combined with a centrifugal clutch might be a better, more economical solution than a fluid coupling in that hp/weight range.

Chumley

 

[briangmr]

Chumley,

Thanks for the feedback. I am sure you are right about the inefficiency and power-to-weight restrictions. I had considered centrifugal clutches, but I would prefer the torque multiplication and smooth response of a torque converter. Engine will be run decoupled from driveline at higher than idle RPM to recharge batteries. I could also use the torque multiplication from the torque converter for high torque, low speed conditions and then lock-up for higher efficiency, low torque conditions. The CVT option is perfect, but the cost may prove prohibitive.

Thanks again.

Brian

 

[butelja]

It sounds like a rubber belt CVT similar to what a snowmobile uses should work. A similar setup was used on the Honda Oddysey, which was a small offroad dune buggy powered by a 250cc 2-stroke engine. They use a combination of cams on the driven pulley and centrifugal weights on the driver pulley to sense torque and engine RPM and vary the gear ratio. At low rpm, the motor pully sheeves are wide apart to allow the belt to be slack. This also acts as the clutch.

 

[DutchDollar]

Hi,

There exist small torque converters on japanese K-class cars like Honda today, Suzuki cappucino, daihatsu, subaru and so on.

I have no data but the engines run 6000-7000 RPM with 75 hp so you should be in similar torque ranges as with 15 hp diesel slow runner. No lock up on these but stiff behaviour. I think their invariant must lie around 500.

DutchDollar

 

[Roncallo]

I cant tell you the specifications on the bike, but I know that Honda made a 4 cycle 400 CC motorcycle with an automatic transmission about 20 years ago. In that time fram I would estimate that engine to be about 20 HP. I dont know if it was a lock up converter.