Planetary gearboxes?

[machin]

A conventional planetary geartrain requires an operating system and a direct engagement clutch. If the system chosen is mechanical, pneumatic or hydraulic then it will be heavier, bulkier and more complex than the current layshaft control systems. This thread is in general terms and in such terms the planetary geartrain would not be chosen.

Auto, thank you for some good technical input.

I must say; I disagree with your thought that an electrically actuated epicyclic gearbox would be lighter than a hydraulically actuated one however (which is implied in your answer, but not actually written).

I am looking at a similar problem at work at the moment; we need to power 6 winches. The winches are used one at a time (I.e not simultaneously), and each is about 7kW. we can either fit hydraulic motors or electric motors to them. The hydraulic motors are far smaller and lighter (roughly 1/5th of the equivalent electric motor weight).... but of course they do require a hydraulic pump, tank, fluid and piping to power them. since we only want to power one winch at a time, it means we only need one 7kW (plus a little for system losses) hydraulic pump unit. The hydraulic system works out far lighter and a lot less volume than the all-electric solution. Plus we can place the hydrualic pump unit wherever we want so we can package the system better whereas the electric system has to have a big heavy motor right there on each winch....

Replace "winch" for gear ratio and its basically the same engineering problem... e.g like my winches; we only want to change gears one at a time so we can use one hydraulic pump for the whole gearbox rather than one electric motor for each ratio . in fact an F1 car already has a hydraulic pump so the weight gain for hydraulic actuation of the planetary is even less...

now I know you'll say the electric motors in your gearbox serve a dual purpose; being also the KERS motor/generators, but I think this makes the situation worse.... imagine the scenario where all but one of the gearboxes stages is freely rotating... that means only one motor can be providing KERS power/charging and that means it must solely be sized for the full KERS output.... the result is that every other electric motor is merely an extra weight to the car.... don't you agree?

[autogyro]

A conventional planetary geartrain requires an operating system and a direct engagement clutch. If the system chosen is mechanical, pneumatic or hydraulic then it will be heavier, bulkier and more complex than the current layshaft control systems. This thread is in general terms and in such terms the planetary geartrain would not be chosen.

Auto, thank you for some good technical input.

I must say; I disagree with your thought that an electrically actuated epicyclic gearbox would be lighter than a hydraulically actuated one however (which is implied in your answer, but not actually written).

lets say it takes 1kW to change gear... if you had an electric motor on each stage of a 7 ratio planetary you need 7x 1kW motors (possibly 6)... the beauty of a hydraulic system is you only need one 1kW hydraulic pump and some small bore tubing.

I am looking at a similar problem at work at the moment; we need to power 6 winches. The winches are used one at a time (I.e not simultaneously), and each is about 7kW. we can either fit hydraulic motors or electric motors to them. The hydraulic motors are far smaller and lighter (roughly 1/5th of the equivalent electric motor weight).... but of course they do require a hydraulic pump, tank, fluid and piping to power them. since we only want to power one winch at a time, it means we only need one 7kW (plus a little for system losses) hydraulic pump unit. The hydraulic system works out far lighter and a lot less volume than the all-electric solution. Plus we can place the hydrualic pump unit wherever we want so we can package the system better whereas the electric system has to have a big motor right there on each winch....

Replace "winch" for gear ratio and its basically the same engineering problem... e.g like my winches; we only want to change gears one at a time so we can use one hydraulic pump. in fact an F1 car already has a hydraulic pump so the weight gain for hydraulic actuation of the planetary is even less...

now I know you'll say the electric motors in your gearbox serve a dual purpose; being also the KERS motor/generators, but I think this makes the situation worse.... imagine the scenario where all but one of the gearboxes stages is freely rotating... that means only one motor can be providing KERS power/charging and that means it must solely be sized for the full KERS output.... the result is that every other electric motor is merely an extra weight to the car.... don't you agree?

Simple answer is no (but you knew that).
In the hybrid or KERS application, only two planetary set would be unavailable for full energy harvesting and then only during shift over lap and even then electrical energy could still be applied and recovered. In direct top all planetary sets would be available. All the planetary sets in the geartrain other than the one in use (and not even one in direct top), are locked together and have no gear to gear movement at all (no need for gear tooth lube). In this condition each set acts as the armature of a five (or six) segement electric motor. The unlocked set still recovers or applies energy but at a different armature rpm. When the vehicle is in pure electric mode (ic engine off and stationary using the motor segments only to drive forwards or reverse)the planetary annulus 'armature' segments can even be rotating in the reverse direction or in unloaded neutral freewheel, they can still apply energy, recover energy, or undertake controlled gear shifting and or direct drive mechanical application locking.

Your winch analogy is similar but not the same engineering problem.
Your prime objective is not to apply all your available torque to one specific output. or to recover energy from that source.

[autogyro]

The electric motors driving your winches are presumably bought in from established suppliers and are conventional designs going back what 200 years in basic technology Machin?
Sets of windings, magnets and basic control system?
Much the same as the current thinking for all electric motor application including hybrid and full electric vehicle traction.


Developments in motor design and even more important the control systems, is opening up a revolution for this technology.
A multi stepped ratio planetary gear set that is also a multi segmented electric motor generator has huge advantages over current gearbox, hybrid and KERS thinking.

[autogyro]

now I know you'll say the electric motors in your gearbox serve a dual purpose; being also the KERS motor/generators, but I think this makes the situation worse.... imagine the scenario where all but one of the gearboxes stages is freely rotating... that means only one motor can be providing KERS power/charging and that means it must solely be sized for the full KERS output.... the result is that every other electric motor is merely an extra weight to the car.... don't you agree?

Sorry Machin, I just noticed that you are not fully aware of how my geartrain design works. I did not wish to bring it up and risk another ban, so I will be brief.
There can never be a condition in drive use when my geartrain has planetary sets freely rotating.
This only occurs when the vehicle is stationary in neutral or when the ic engine is frewheeled to stationary using the first set.
When any one ratio is locked in engagement and the vehicle is driving all the other planetary sets are locked internaly with no gear movement and the torque flows through these sets as through one rotating unit.
The gear sets DO NOT freewheel.
Therefore ALL are available as motor/generator armatures at all times.

[Tommy Cookers]

Just a few points before I forget,

My EM creeper clutch combined with a torque-modulated dog clutch (I meant to say) should drop into semi automatics easily. 99% of the time in a manual or semiauto a friction clutch rated at 200% torque is being modulated at less than 20% torque, the software torque control would allow dog engagement before upping the torque.

This is for a one step at a time revolution.


The Fell locomotive (differential input planetary? )gearbox was over 99% efficient.
Pratt & Whitney are into a huge programme of geared turbofans. These are medium sized, up to about 30000 lb thrust. 99.5% gearbox efficiency

Yes, gearing is needed in electric motoring (unless all our cars are to be slaved together).

Shame that coal-fired steam generated electricity can be presented as wholesome and efficient if used in a car ! Shame that it is hugely subsidised re first cost and exemption from motor fuel duty !

In integrating mechanical and electrical aspects, let's consider the greater EM efficiency of a liquid magnetic flux path, rather than air, so design the electrical electriacl side around this. Don't let the electrics people (another self-serving clique) be the tail wagging the dog !

[Tommy Cookers]

Also technology/scope for CVT or efficient auto ? I think Mr Fell would appreciate it !

[Richard]

Discussion specific to Autogyro's ESERU moved to the relevant thread

viewtopic.php?p=332401#p332401

Sorry to disrupt this thread, but the ESERU is a sensitive topic on the forum!