2 Speed Gearbox

Open for any sort of non-technical discussion regarding EVs
Post Reply
gttool
Groupie
Posts: 79
Joined: Mon, 26 May 2008, 01:46
Real Name: Geoff OToole
Location: sydney
Contact:

2 Speed Gearbox

Post by gttool » Fri, 22 May 2009, 02:48

Running a cluch center reduces the harshness of on/off throttle due to the inertia of the motor ?

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

2 Speed Gearbox

Post by Electrocycle » Fri, 22 May 2009, 15:33

I have just found a modern auto box with lockup torque converter and I have an 11kw induction motor waiting to go on it :)

The only problem I can see so far is that the auto is much heavier than a manual!

I have looked into controlling the auto boxes before, when I wanted to make a push button shift controller to replace a dodgy auto computer.

With careful control of the shift times and hydraulic line pressure (there's a solenoid that drops the line pressure when it's energised) I think it'd be fairly easy to get nice shifts without the torque converter.
The Engine Whisperer - fixer of things

AMPrentice
Senior Member
Posts: 401
Joined: Tue, 05 Aug 2008, 19:30
Location: down south

2 Speed Gearbox

Post by AMPrentice » Fri, 22 May 2009, 16:52

Which auto Ecycle?
You definately wont need the TQC as the torque of the motor should be superior to the ICE hence their need for one. That in itself will save plenty of weight.
http://www.zeitgeistmovie.com/

No Queen, No Prime Minister, No hierarchical system to break down our communities
Never vote Labour, Liberal or Maggots like them.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Fri, 22 May 2009, 19:11

Squiggles wrote: Are clutchless gear changes really a problem when using an electric motor?
I always thought that the shock springs in a clutch plate were there because of the impulse nature of the ICE power, where as the electric motor has a much smoother characteristic, add to that the virtual lack of mechanical resistance when in power off mode.
The problem is not the shock loading effect of a sprung clutch disk as performance clutch plates often have no springs at all. Basically the springs in the clutch plate takes up the load when the clutch is let back out and the clutch plate is once again trapped between the pressure plate and the flywheel causing a direct hook up. Because we are trying to avoid having a heavy reciprocating mass, (roughly 13-15kgs with pressure plate) which the motor doesn’t need, and the associated extra weight sitting on a ball bearing... Petrol engines use plain bearings that handle weight load far better.

So the whole purpose of trying to get rid of the clutch is not because it isn’t required but rather to make the electric motors life a much happier one.

The biggest issue is more related to changing gears without crunching or wearing out the syncros in the box. It’s all about slowing the input shaft speed of the gearbox so the gear change can be made smoothly. When the clutch is applied the motor and gearbox are completely disconnected, when an electric motor is directly coupled to a gearbox it has the weight of the motor reciprocals trying to turn.

Auto is probably a better way of doing it but has a whole heap of other challenges to work around. Again you really don’t want the weight of a heavy torque convertor with a few litres of ATF sitting on the end of the electric motor either. An auto is probably better equipped to make smoother gear changes that an manual because the auto uses clutch packs inside the box to give the same sliding action that the clutch produces in a manual.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Fri, 22 May 2009, 19:13

Electrocycle wrote: I have just found a modern auto box with lockup torque converter and I have an 11kw induction motor waiting to go on it :)

The only problem I can see so far is that the auto is much heavier than a manual!

I have looked into controlling the auto boxes before, when I wanted to make a push button shift controller to replace a dodgy auto computer.

With careful control of the shift times and hydraulic line pressure (there's a solenoid that drops the line pressure when it's energised) I think it'd be fairly easy to get nice shifts without the torque converter.
If you take out the convertor and machine off the factory bellhousing it brings them a little closer.
gttool wrote: Running a cluch center reduces the harshness of on/off throttle due to the inertia of the motor ?


Nope becuase it only really has an effect during clutch re-engagement. So a solid coupling or a sprung one would make little difference on a manual, maybe lessen the gear shock loading on the gears a bit.
Last edited by EV2Go on Fri, 22 May 2009, 09:16, edited 1 time in total.

User avatar
Johny
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

2 Speed Gearbox

Post by Johny » Fri, 22 May 2009, 20:08

I wonder when those dual clutch gearboxes as used by Audi (and others) will appear in wrecking yards. I guess they might get picky if the gearbox ECU can't talk to the engine ECU. Nice gearbox though. Hmm - probably not available for RWD.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

2 Speed Gearbox

Post by Electrocycle » Fri, 22 May 2009, 20:11

a sprung clutch center does help to dampen the engine's torsional vibration and makes the drive train quieter.
I found when I ran a solid center clutch I had harmonics happening at certain speeds. Obviously this is not a problem with an electric motor!
The solid center clutch was fine when engaging, and if anything was less prone to shudder than the sprung performance clutches I've used.


The auto box I have is from a Silvia. It's a bit of overkill, but it's free - and easy to mess around with.
These boxes can handle massive torque.

I'm tempted to try it with the torque converter on, and make good use of the lockup - mainly because it's simpler from a conversion point of view.
Removing the torque converter and driving the box directly would also be nice, especially with some well integrated control of the gearchanges.
The Engine Whisperer - fixer of things

BG
Noobie
Posts: 20
Joined: Wed, 04 Mar 2009, 17:54

2 Speed Gearbox

Post by BG » Fri, 22 May 2009, 20:47

Have you thought of getting rid of the rest of the gearbox and just using the lockup torque converter?? It might seem silly at first, but it could solve a bunch of problems. The torque multiplication (3x ?) allows you to do a hill start in a gear which would normally be left for cruising. It would also give you that 'kick' off the line which is kind of lacking in induction motors.. and you don't need to worry about changing gears.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Fri, 22 May 2009, 20:52

Johny wrote: I wonder when those dual clutch gearboxes as used by Audi (and others) will appear in wrecking yards. I guess they might get picky if the gearbox ECU can't talk to the engine ECU. Nice gearbox though. Hmm - probably not available for RWD.


Are you talking about a twin disk clutch? if so why would you be so cruel to yourself. A well designed single will work just as well as a duel without the nightmare that accompanies the twin plate.

Andrew I was thinking about using the same box for my 180, but decided on the C4 as they worked out only slightly dearer around the $6k mark instead of about $5k, and once you had all the billet input shafts etc in it and was capable of higher power levels, but I think a freshened up or standard rebuilt Jatco box out of a Silvia would be more than enough for any electric motor. Memory serves me right 4th gear was an electronic overdrive on the Jatco.

Can’t remember was the bell housing bolted on or cast into the main case?

BG check page 4
Last edited by EV2Go on Fri, 22 May 2009, 10:53, edited 1 time in total.

User avatar
Johny
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

2 Speed Gearbox

Post by Johny » Fri, 22 May 2009, 20:58

EV2Go wrote:Are you talking about a twin disk clutch? if so why would you be so cruel to yourself. A well designed single will work just as well as a duel without the nightmare that accompanies the twin plate.

No, these gismos

Squiggles
Senior Member
Posts: 742
Joined: Wed, 22 Apr 2009, 03:19
Real Name: Neil
Location: Newcastle NSW

2 Speed Gearbox

Post by Squiggles » Fri, 22 May 2009, 21:03

Johny wrote: I wonder when those dual clutch gearboxes as used by Audi (and others) will appear in wrecking yards. I guess they might get picky if the gearbox ECU can't talk to the engine ECU. Nice gearbox though. Hmm - probably not available for RWD.


I drive a diesel golf with said dual clutch box and 320Nm of torque, fantastic thing gear changes are near undetectable. The box is a sealed non serviceable unit, hope it has a long life!! Apparently a replacement is worth $7k+.

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Fri, 22 May 2009, 21:53

ok not the cheapest gearbox on the market (not the dearest either). Not very good without pictures, but it sounded like the clutches were in the actual box much like an auto.

So does it use a convetional clutch, it doesn't sound like it?

Sounds perfect for an EV.

User avatar
Johny
Senior Member
Posts: 3729
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

2 Speed Gearbox

Post by Johny » Fri, 22 May 2009, 22:27

Google "dual clutch gearbox". There are a few videos etc.
The wikipedia article suggests some interesting implementations such as the Nissan and they have been around for long enough to be in crashes - especially by those who they would appeal to...

Squiggles
Senior Member
Posts: 742
Joined: Wed, 22 Apr 2009, 03:19
Real Name: Neil
Location: Newcastle NSW

2 Speed Gearbox

Post by Squiggles » Fri, 22 May 2009, 23:49

They are worth studying.
The clutches drive two concentric shafts (one inside the other). each shaft drives half the gears 1,3,5 & 2,4,6. Computer preselects a gear on the non driven shaft, the clutches swap and you don't feel a thing.
I suspect that there is a bit of rev matching going on as well, after all these things are computer driven so all is possible.

edit: yes the clutches are inside, from memory they are multi-plate wet type.
Last edited by Squiggles on Fri, 22 May 2009, 13:51, edited 1 time in total.

Arniem
Noobie
Posts: 4
Joined: Wed, 30 Jul 2008, 22:57
Real Name: Arnold Mitt
Location: Rozelle NSW

2 Speed Gearbox

Post by Arniem » Sat, 23 May 2009, 02:38

I would really like to hear what learned people on this forum think about the question posed by coulomb and BG, that would it be viable to attach a TC directly to a motor, and use that to supply "variable gearing", instead of using using an auto box (with or without a TC).

It's an interesting idea, with the main benefit being that the motor current draw at take off, or during times of high climbing, (and hence the heat generated in the controller, cables, and at the batteries) will be reduced even though there really only one gear - that provided by the diff (at the expense of road speed - can't get something for nothing...). Although maximum torque from a motor is available at basically 0 RPM, it is at the expense of high current draw. If I understand the physics of it all, reduced current draw would also mean driving range is increased (fewer coulombs leaving the batteries for the same distance). The idea, of course, would be to lockup the TC as soon as possible, and slip out of it when the current draw becomes too high.

I can see two disadvantages - TCs typically have a one-way clutch or ratchet, which prevents the TC rotor going into reverse. Hence, no reverse by simply switching the motor polarity (though maybe you could start the TC in locked mode when in reverse?). The other is activating the lockup mechanism - I think (though I maybe wrong here) it needs TC fluid pressure, activated by a solenoid, to push the TC surfaces together to create the lockup. EV2Go pointed out that the lockup mechanism can't take large amounts of torque - why not use an beefy oversized TC (from say a V8) instead?

antiscab
Senior Member
Posts: 2443
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

2 Speed Gearbox

Post by antiscab » Sat, 23 May 2009, 09:38

Arniem wrote: If I understand the physics of it all, reduced current draw would also mean driving range is increased (fewer coulombs leaving the batteries for the same distance).


No, current at the battery will *increase* as you are both developing more mechanical power at the wheels, and the system effeciency has been signifcantly lowered (since you are letting the TC slip).

only motor side current is reduced when achieving the same torque at the differential (which if you are using the torque converter, you would be trying to make more).

Matt
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

2 Speed Gearbox

Post by Electrocycle » Sat, 23 May 2009, 16:38

BG wrote: Have you thought of getting rid of the rest of the gearbox and just using the lockup torque converter??


yes, this is what I mentioned in the previous thread about autos :)

The only hassle is that the lockup part of the lockup torque converter is actually in the gearbox. There's just another clutch that locks the input and output of the torque converter together.
The Engine Whisperer - fixer of things

User avatar
KDRYAN
Groupie
Posts: 122
Joined: Sun, 28 Sep 2008, 16:26
Real Name: Kim Ryan
Location: Cairns

2 Speed Gearbox

Post by KDRYAN » Sat, 23 May 2009, 19:54

Hi All
I have tried the clutchless gearbox and direct drive assembly. Both have there problems.
I am now building a direct drive unit using a Toyota L-130 automatic transmission with lockable torque converter. All the internals/ gears will be removed from the transmission, linking the input shaft direct to the pinion transfer gear is the only internal modification. I will also need to install a small low pressure oil pump to feed the oil system for when standing at traffic lights and for reversing the motor / transmission unit.

The clutch in the torque converter is engaged / disengaged with the use of oil pressuer on both sides of the clutch plate. When oil pressure is equal on both sides of the plate the clutch is disengaged, reducing pressure on the front side engages the clutch.

Should have the Proton up and running within a month I hope all going well, hopefully with positive results.

Regards
Kim

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Sun, 24 May 2009, 03:01

For those who don't know how a torque convertor works take a look at this http://www.youtube.com/watch?v=MvLoX0z9qoY then it will become very obvious why it is the weak link (not pyshically but efficency) as he describes in the video that stator basically just sits there and spins below a certain rev which results in no movement of the car.

i.e energy in no movement out. This is how the stall or slip is produced that allows the petrol engine to build revs to take off, and it should also be obvious even at higher rpm it still in very inefficent as it is using the ATF to drive the things.

As I said before the lockup mechanism should only be engaged in top gear when the maximum load is off the torque converter. It is only like a roll pin and will shear easily if you try to engage under any kind of load.

User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

2 Speed Gearbox

Post by Electrocycle » Sun, 24 May 2009, 14:33

yeah the torque converter is not very efficient, but it does make for an easy way to smoothly increase takeoff torque in a fairly small package.

The lockup can be controlled in sync with the motor so it doesn't have to lock up under load.
The Engine Whisperer - fixer of things

User avatar
EV2Go
Senior Member
Posts: 2059
Joined: Wed, 16 Jul 2008, 00:21
Real Name: Paul
Location: Brisbane 1963

2 Speed Gearbox

Post by EV2Go » Sun, 24 May 2009, 21:58

Don't get me wrong I don't fundementally see anything wrong with using a torque convertor to improve a torque increased take off, but when it is all said and done once you get to the point of trying to make the torque convertor a stand alone affair you may as way use a simple gearbox where this thread started.

User avatar
acmotor
Senior Member
Posts: 3595
Joined: Thu, 26 Apr 2007, 03:30
Real Name: Tuarn
Location: Perth,Australia

2 Speed Gearbox

Post by acmotor » Sun, 24 May 2009, 22:17

... or just use a bigger emotor ! Image
iMiEV MY12     105,131km in pure Electric and loving it !

aversion
Noobie
Posts: 4
Joined: Sun, 17 May 2009, 23:50

2 Speed Gearbox

Post by aversion » Mon, 25 May 2009, 06:00

Might be missing something here (or quite a lot Image ) but could you adapt something like a landrover overdrive unit or a defender o/d which is operated via solenoid?

User avatar
acmotor
Senior Member
Posts: 3595
Joined: Thu, 26 Apr 2007, 03:30
Real Name: Tuarn
Location: Perth,Australia

2 Speed Gearbox

Post by acmotor » Mon, 25 May 2009, 06:12

Lando OD is 0.782:1 or to put it another way, 1.28:1 Image
What is required in a two speed box is more like 2:1 ? to make enough difference to go to all the trouble of two ratios, even if the OD was put in back to front since one of the ratios needs to be like second gear. (assuming typical emotor revs, not a 10,000rpm beast !) Image   
iMiEV MY12     105,131km in pure Electric and loving it !

CZal
Groupie
Posts: 67
Joined: Tue, 12 May 2009, 21:20
Real Name: Costa
Location: Melbourne

2 Speed Gearbox

Post by CZal » Mon, 25 May 2009, 15:37

How about your transfer case Tuarn? for those of us who don't mind coming to a complete stop to shift down.... can you shift up while on the move?

Post Reply