patent drawingThree years to the day after I filed the non-provisional patent application with the US Patent and Trademark Office, the examiner has allowed a patent for my Variably Expanding Chain Transmission to issue! Once the Notice of Allowance is mailed, and after I pay the requisite fee and submit any required changes or corrections to the application, the patent should issue in a few weeks! At that time, VECTr will no longer be “patent pending,” but an actual patented invention!

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So, testing and adjustments were progressing in August 2017, until . . .

Hurricane Harvey struck Houston, and well, things got off-track. We were fine, but a lot of people were not, and the day job prevented invention work for a while.

But, the latter has resumed, and progress has been made. Here’s a shot of the working model working.

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VECTr – Variably Expanding Chain Transmission (Patent pending)

A video of the 5 bolt design in action will be coming soon! Check back for updates.

 

 

More Improvements

Posted: July 31, 2017 in Uncategorized
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Chain ring bolts interfere with movement of gear segments

It has been a while since I updated the progress being made on VECTr (in part because that progress has been slowed by my day job consuming the free time I would have devoted to inventing). Well, a couple of developments have taken place since January. First, while the 110 BCD five gear segment design showed promise, the placement of the bolts in that design interfered with the movement of the gear segments.

So in January, I modified the design of the base plate to allow the free movement of the gear segments, and began testing the design in February.

 

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Throughout February and March, I tested various designs for the locking pin, trying to find one that would keep the pin perpendicular to the plane of the base plate while sliding into and out of the locking notches in the base plate. In addition, I was trying to figure out the best spring type to bias the pin into the locked position, a type that would fit into the very small space between the gear segment and the base plate.  The locking pin/spring combination is really the key to VECTr being able to achieve expanding gears at a light weight and hopefully low production cost.

 

One other improvement was to affix the control plate guide more securely to the frame. In the end, I replaced the temporary wooden bracket with a steel one I fashioned which is much more durable, and will probably be incorporated into the final product design.

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New 5-Bolt base plate with gear segments and control plate guide affixed with steel bracket.

Now, as I had indicated in the prior blog post, I still need to find the proper angles for the control plates that will unlock and move the gear segments both from inner to outer positions, and vice versa.  We are getting close!

 

In the last post, I said that I had been focusing my attention on a 5-arm 110 BCD version of VECTr that used the same idea for the locking pin as the version in the video.  That basic idea consists of the locking pin moving laterally when contacting the control plates to unlock the gear segment, and being pushed along the contour of the control plate into its new radial position as the crank turns.  I had said that I had been trying to get this to work, and the fact that I was trying, meant that I was unsuccessful.

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Old version of control plate mechanism, with long sweeping outside plate (on the left).

Well, it’s a funny thing about tinkering that sometimes ideas strike you while trying to do something else. When I was working on the laterally locking pin design last spring, I was indeed unsuccessful, and so went back to the drawing board (or CAD program) and came up with perpendicularly drawn locking pin design.  And in the fall, I was trying to get this new design to work, when, seeing some parts from the old design on my desk, I wondered again why it wouldn’t work.  So I reassembled them, but tested them with the control plates for the new design, and what to my wondering eyes should happen, but the hybrid of old and new worked (sort of).  I discovered that it wasn’t the lateral locking pin that was the problem, but the control plates (which seemed necessary for the version in the video and had worked there — see image to the right).

 

 

Instead of the long sweep for the outside control plate, the new design had two simple angled control plates, but they seemed able to unlock and re-position the gear segment of the old design, but not as smoothly as they should.  So, as a result, for the last few weeks, I have revived the old design and tested various shapes for the control plates.

20170127_113644Finally, I found that by modifying the inside control plate from the old design, it would contact the locking pin on the gear segment at an appropriate angle to unlock it and slide it to the desired radial position.  (It took much trial and error to find the appropriate angle — a better understanding of geometry and the physics of friction might have led to a good design, a priori, but what can you do . . . .)

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Gear segment being moved to the outside of the expansion arm by contacting the new inside control plate.

 

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The gear segment in the new outermost position with its locking pin released to lock the gear segment in place.

 

So, this is (hopefully) the last major hurdle to finalizing a truly functional design.  I know of many smaller hurdles and tweaks that will be necessary, and I will probably discover others, but I feel good that VECTr is getting closer to the marketable stage.

Further Refinements

Posted: January 6, 2017 in Uncategorized

While the original video of VECTr garnered positive feedback and interest, there were many questions about its operation as well as suggestions for improvement.  (You can see a representative sample in the comments on various pages of the this website.)  Easily, the number one criticism was that the expanding chainring design has been tried and found commercially wanting.  As I continue to point out, there have been many expanding chainring designs that have not had sustainable commercial success, but the differences among them probably account for their varying degrees of profitability.  Trying to find the simplest, most reliable design producible for the least cost is the true challenge in design in general, and specifically in the expanding chainring transmission game.

20170102_173953There were concerns specific to the VECTr design which I have spent my time trying to address.  The first had to do with the smoothness of the operation.  It has always been an aim of the design process to make a device which is compatible with current bicycle standards, and so I made a four gear segment mechanism which could be fitted to the 64 BCD fittings of a MTB crank arm.

It was noted, however, that this made the operation of VECTr appear “lumpy” and uneven, and viewers thought it would make for an uncomfortable ride. Yet, increasing the number of gear segments would increase steps between the gear ratios, and thus limit the range of settings for the device.

20170102_174309aAlso, the design of the locking/adjustment mechanism of the gear segment consisted of three pieces for the sliding motion, plus a pin/bolt and spring for the locking motion, in addition to the actual chain-engaging gear segment.  These were all held together with simple blind rivets, which I knew were none too strong, and probably would not hold up to the stresses of actual road use.  In working up some cost estimates for the manufacture of VECTr in that iteration of the design, it became clear that it would be difficult to entice a manufacturer to license the design, or for me to make them out of my garage.  I thought, too, that simplifying the design of the gear segment mechanism would decrease the weight and offset the additional mass of added gear segments.

20170102_174008The result of rethinking these issues led me to design VECTr with five expansion arms (fitted for 110 BCD cranks) and five gear segments which would slide within narrower channels, still having notches on one edge into which a locking pin would fit.  In a prior blog post I detailed how I had to call upon my trigonometric acumen (latent and seldom used as it was) to work out the proper spacing of the notches for the five arm design.

20170102_174223In this new design, I replaced the three-piece sliding parts with simple bolts (which also took the place of the rivets) and the locking bolt sliding with the rest; it would be biased into locking position by an external elastic band or other small spring.

I spent much of my time working on VECTr this past year (when I could work on it) trying to get this design to work, as well as working to make the control mechanism compatible with a Shimano indexed shifter.  I detail some of that work in a prior blog post, too.

Given that I say that I tried to get this new design to work is a pretty good indication that it was not successful.  I will have to let you know the insights this process gave me that led me to the current design, which I think shows even greater promise.

Not Dead Yet!

Posted: January 2, 2017 in Uncategorized

drawingDespite the dearth of posts on VECTr, progress has been proceeding, albeit in fits and starts. (I have been making some major transitions in my day job, too,  over this time.)  Encouraged by the interest in the original video of VECTr’s operation (which now has over 12K views), I sought to refine and simplify the design so as to make it more feasible for me to conduct a first run at manufacturing it commercially.  I also tried to take into account suggestions for making it more compatible and smoother in its operation.  In the weeks ahead, I will be detailing the improvements I made, designs I tried, and challenges I encountered in these past intervening months.  I will also be giving updates on the state of the current design and progress in testing it, hopefully continuing to move toward the point of making a salable product for widespread use.  Stay tuned for further updates!

Thanks to all of you who have visited the original VECTr video on YouTube. Our number of visitors has now exceeded 10,000! Check out an updated version of the video here: https://www.youtube.com/watch?v=fVFmUcA6sjc.