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I can see its advantage over a standard CVT
I think it would be better if the lever was driven by a motor so the rider could have a 'Sports' Mode at the touch of a button.
Sort of like a poor mans Burgman 650 Electronic CVT :D

Andy
 

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I'm with the others on another belt but there are other things that would concern me like the friction between the two belts and if the secondary belt was able to pull/adjust the pulleys they why wouldn't the load being driven do the same thing without the input? There would have to be some way to lock the ratio.
 

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I can't see how this would have any advantage over the gear drive system in the 650s CVT. It's at least as complicated and as others have said you have another belt to worry about.

Maybe if you were trying to set up a manually shifted CVT instead of an automatic one. Maybe hook the shift up to a throttle like grip on the left side so you could adjust the ratio to what ever you wanted instead of relying on a variator or ECM to do it for you.
 

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Maybe if you were trying to set up a manually shifted CVT instead of an automatic one.
Funny when I first saw it I thought suicide shifter. On the Burgy you could just pull the CVT motor and add a geared lever to manually shift. :D
 

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I think you guys are looking at this slightly wrong, The arm and extra belt assembly replace a conventional variator/weight setup and make it manually adjustable instead. so instead of roller weights etc... you would have either a level or and electronic motor changing the gearing for you.
 

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Discussion Starter #9
Hello.

Please take another look, now at:

http://www.pattakon.com/pattakonPatBox.htm#PECVT






It is the electronically-controlled version of the PatBox CVT.

In the PatBox (the mechanical and the electronic versions) the auxiliary belt is not transerring energy - power.
The loads on the auxiliary belt and on the rollers on the lever are quite small.
There is no sliding between the two belt.
The auxiliary belt just follows - without resistance - the motion of the external periphery of the V-belt (it is like the front wheel of your scooters that rolls on the road surface transferring a part of the weight of the scooter).

Thanks
Manolis Pattakos
 

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Manolis:

Is this set up an idea, or do you have a working prototype with some endurance/functional testing accomplished? I like the idea of having selectable gearing, but also enjoy the simplicity of a CVT for around town riding. The CVT is a proven well engineered method to variable gearing without a lot of complicated hardware to make it function. It isn't without its shortcomings, but still remains the gearing method of choice for almost every Scooter Manufacturer in the world.
I could see your application being applied to a specially designed scooter set up for Drag races, but most of those guys use a a version of the HiT clutch.
If you had a link to an actual working model rather than a 3D CAD it may be more sellable. For now, I see this as perhaps a good idea but with no proven mileage behind it to reinforce your reliability and "Greener" claims.
 

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Discussion Starter #11
Hello Roger32849.

The PatBox is a recent project we have here in pattakon.
There is no prototype, yet.

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Manolis Pattakos
 

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Manually controlled CVT transmissions are a very old idea, and was used to regulate or fine tune speed of conveyor belts and other stuff in production lines, to name an application.
Now frequency converters are used instead.
 

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Discussion Starter #13
Manually controlled CVT transmissions are a very old idea, and was used to regulate or fine tune speed of conveyor belts and other stuff in production lines, to name an application.
Now frequency converters are used instead.
Hello ErikDK;797161

Please take another look at the post no.3 of this thread to see the Electronically-controlled version of the PatBox CVT .

Its functionality (modes of operation) is equivalent to SECVT of Suzuki Burgman 650. Isn't it?

Instead of pushing the slidable sheave of the front pulley (as in Burgman SECVT), in the PECVT PatBox an auxiliary belt rides on the V-belt at the one pulley side. The lever pulls the auxiliary belt that forces the V-belt to get deeper into the one pulley.

The auxiliary belt follows – without resistance – the motion of the external surface of the V-belt, adding neither friction, nor wear.
In case the auxiliary belt is a steel band (like those used in the V-belts in the automatic car’s CVT’s) the auxiliary belt acts as a cooler (a fin) that further reduces the V-belt temperature.

Now think: can the SECVT be used in a conventional CVT (those with the centrifugal variator) of a scooter to provide additional modes of operation?
Manual modes or automatic modes, it doesn't matter.
The PatBox can because it controls the V-belt in a different way.

The SECVT and the PECVT differ also in the loads acting on the V-belt.

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Maolis Pattakos
 

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The auxiliary belt follows – without resistance – the motion of the external surface of the V-belt, adding neither friction, nor wear.
I'm sorry but I do not see that being the case with force applied to a rotating belt.

Now think: can the SECVT be used in a conventional CVT (those with the centrifugal variator) of a scooter to provide additional modes of operation?
Manual modes or automatic modes, it doesn't matter.
The PatBox can because it controls the V-belt in a different way.
Correct me if I'm wrong but I do not see a way in the plans of holding the spring loaded pulleys from moving on their own as they are either on the driven end (assuming the ratio changing belt is on the driven end then the load end) or load end (assuming the ratio changing belt is on the load end then the driven end). Basically if the ratio changing belt is held changing load on the other one will cause the belt to unload or slip pulling on the other spring loaded pulley.

On the Burgman CVT the secondary pulley can't move the primary pulley because it is being held by the screw drive from opening or closing due to the electric motor/controller. Your design only holds the belt from moving outward not inward if the other pulley pulls on it from what I can see this will cause a loss of tension between the drive and ratio changing belts.
 

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Discussion Starter #15
Hello MJR.

You write:
“I'm sorry but I do not see that being the case with force applied to a rotating belt.”

Think of the front wheel / tire of your scooter.
It passes to the road nearly half of the scooter weight and rolls on the surface of the road without resistance / friction (only when you press the brake, only then a friction force – opposite to the direction of the motion of the wheel – is created that consumes energy and decelerates the vehicle).
During normal driving, the friction between the front tire and the road surface is normal to the vehicle motion (this is why it consumes no energy).

If you are still confused,
think of the auxiliary belt as a belt “tensioner”, like those used in the timing belt that drives the camshaft of the car engines.
The tensioner is a free roller that pushes the timing belt to keep it in “tension”. For as long as the peripheral speed of the tensioner equals to the speed of the timing belt periphery, the energy consumed in a tensioner is insignificant.
In a similar way, with the peripheral speeds of the auxiliary belt and of the V-belt – wherein the one abuts on the other – being equal, there is no energy loss (friction).


You write:
“Correct me if I'm wrong but I do not see a way in the plans of holding the spring loaded pulleys from moving on their own as they are either on the driven end (assuming the ratio changing belt is on the driven end then the load end) or load end (assuming the ratio changing belt is on the load end then the driven end). Basically if the ratio changing belt is held changing load on the other one will cause the belt to unload or slip pulling on the other spring loaded pulley.”

There is a spring per each pulley.
The spring on the pulley wherein the auxiliary belt abuts onto the V-belt is adequately stiffer. This means that when you leave the lever free, the system goes to the condition wherein the pulley wherein the auxiliary belt abuts on the V-belt gets at its maximum effective diameter.
The two halves of the other pulley are apart from each other and the spring is compressed.

Suppose now you pull, by the lever, the auxiliary belt to get deeper in the pulley wherein the auxiliary belt abuts on the V-belt, and the effective diameter of this pulley decreases. The spring of this pulley is further compressed.
The spring of the other pulley pushes the two halves closer to each other, increasing the effective diameter. The increase of the effective diameter of this pulley stops when the V-belt tries to compress the “adequately” stiffer spring of the other pulley.

If it is not yet clear,
think that the pulley wherein the auxiliary belt is NOT abutting onto the V-belt, is nothing more than the rear pulley of the Suzuki Burgman SECVT; when the front pulley of the SECVT is pushed, by the screw shaft, to a bigger effective ratio, the “constant length” V-belt gets deeper into the rear pulley compressing the spring.

Instead of pushing (by the screw shaft) the slidable sheave of the front pulley of the SECVT to approach the other sheave (increasing the effective diameter of the front pulley and forcing the back pulley, through the V-belt, to get to a shorter affective diameter), in the PatBox PECVT the auxiliary belt and the lever do the work of the screw-shaft of the Suzuki SECVT.

Because the auxiliary belt acts directly, in the “correct” direction, the necessary force it has to apply to the V-belt is several times smaller than the force that has to be applied to the slidable sheave of the front pulley of the SECVT of Burgman (this depends on the angle of the cones).

If you think deeper, you can see a substantial difference in the V-belt loading in the two cases (SECVT and PECVT).


You write:
“On the Burgman CVT the secondary pulley can't move the primary pulley because it is being held by the screw drive from opening or closing due to the electric motor/controller. Your design only holds the belt from moving outward not inward if the other pulley pulls on it from what I can see this will cause a loss of tension between the drive and ratio changing belts.”

As explained before, the spring of the pulley wherein the auxiliary belt abuts on the V-belt in the PECVT PatBox is adequately stiffer / stronger than the spring of the other pulley.
Does it answers to you?

Thanks
Manolis Pattako
 

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Interesting, but how from p3 to p4 the speed is increasing whereas it can be kept constant at given rpm. Also by "progressively releasing the lever 7" is meant the driver has to regulate the acceleration manually all the time being involved in the process of controlling throttle, AND the lever? Sounds more complicated than just kicking the gear and applying the throttle after brief play with the clutch on a conventional motorcycle. :confused:
 

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Discussion Starter #17
Hello Bolzen.

You write:
“but how from p3 to p4 the speed is increasing whereas it can be kept constant at given rpm”.

The “centrifugal” variator does this in most CVT’s.
The effective diameter of the one pulley increases, of the other pulley decreases and the scooter’s speed increases without a noticeable (or substantial) increase of the engine revs.

The PatBox can operate in various ways.

For instance, the CVT can continue the automatic operation and only when the rider wants / needs a shorter transmission ratio he can use the lever.

Or the rider, by a button or lever, can change the “preloading” of the restoring spring of the lever, resulting in a more “sporty” behavior” (it is like replacing – on the fly – the rollers of the variator by lighter ones).

The PatBox can also be electronically-controlled (in this case it does not need a centrifugal variator), just like the Suzuki Burgman SECVT. The control unit, based on several operating parameters, displaces the lever and selects the desired transmission ratio (in this case each pulley has its own spring).

If you want to add to a conventional cheap CVT a number of manual ratios, here is a version of the PatBox CVT:



In this case the gear shift is made by “just kicking the gear and applying the throttle (without playing with a clutch)”.

Take a look and let me know to further explain.

Thanks
Manolis Pattakos
 

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The “centrifugal” variator does this in most CVT’s.
The effective diameter of the one pulley increases, of the other pulley decreases and the scooter’s speed increases without a noticeable (or substantial) increase of the engine revs.
Oh, that is the graph for the fully open throttle then, is that it. Now if you want to raise rpm first to say 8000 and release the lever after i seem to smell a slipping belt, or do i?
 

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I'm sorry but I do not see that being the case with force applied to a rotating belt.
Looks like he means the secondary belt is resting over the V and running concurrently with it, pushing it to another position at request of a lever much as cliffyk does when installing the clutch and the variator, using a modified wooden handle.
 

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Discussion Starter #20
Oh, that is the graph for the fully open throttle then, is that it. Now if you want to raise rpm first to say 8000 and release the lever after i seem to smell a slipping belt, or do i?
If the CVT is capable of transfering the power of the engine at 8000rpm, I can't see how you can make the V-belt slipping.

Thanks
Manolis Pattakos
 
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