Telescoping Piston Concept

Telescoping Piston Concept

Joined: June 30th, 2011, 11:13 pm

May 23rd, 2012, 8:07 pm #1

Lots of very technical chat below about supersizing pumpers and the like; most of which is beyond my comprehension. A thought occured to me that a telescoping piston would drive a significantly larger volume of air into a valve. This design, if feasible, would be very useful for SSP-type pumpers, but may have value in a multi-pump scenario.



Does this concept make any sense at all?
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Joined: April 23rd, 2012, 11:10 pm

May 23rd, 2012, 8:34 pm #2

Sure does !

Been pondering it meself, but haven't got the details quite worked out.

The surface area of the larger diameter gets real big, real fast, so the idea does have merit for both volume, and pressure.
Kinda sorta a multi-stage compressor, all in one stroke. ( if the details of making it work materialize )

The full size big piston would do high volume, low pressure, while inner smaller pistons would do progressively less volume, but higher pressure, having been pre-charged by the larger diameter.
As the surface area /diameter reduces, so does pumping effort due the proportionally advancing mechanical advantage.
Think about the "gearless" constant RPM transmissions in higher end cars these days.
Real high efficiency there.

Of course, taken to extreme, it's a collapsable cup seal.
Hmmm....
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Joined: March 1st, 2002, 12:22 am

May 23rd, 2012, 9:10 pm #3

cant seem to find the post though. Fairly recent....

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
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Joined: July 17th, 2005, 5:16 pm

May 23rd, 2012, 9:13 pm #4

Lots of very technical chat below about supersizing pumpers and the like; most of which is beyond my comprehension. A thought occured to me that a telescoping piston would drive a significantly larger volume of air into a valve. This design, if feasible, would be very useful for SSP-type pumpers, but may have value in a multi-pump scenario.



Does this concept make any sense at all?
I'm too weak in engineering to know if it will or not but it's EXACTLY the sort of creative conceptualization needed to resolve the issues that prevent the MSP from dominating airgunning again.

From my weak perspective it appears to have a good chance of working. Hope to see others far more qualified than myself tell us why it will or won't. Tom
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Joined: April 28th, 2010, 12:23 am

May 23rd, 2012, 9:20 pm #5

Last edited by robnewyork on May 23rd, 2012, 9:22 pm, edited 1 time in total.
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Joined: April 1st, 2009, 3:18 am

May 23rd, 2012, 9:37 pm #6

Lots of very technical chat below about supersizing pumpers and the like; most of which is beyond my comprehension. A thought occured to me that a telescoping piston would drive a significantly larger volume of air into a valve. This design, if feasible, would be very useful for SSP-type pumpers, but may have value in a multi-pump scenario.



Does this concept make any sense at all?
...will still be the surface area of the largest piston diameter. The same end result if the design was just a large diameter piston the same diamter of the larger telescopic piston.

Once all the pistons have been collapsed, the piston is solid.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: April 1st, 2009, 3:18 am

May 23rd, 2012, 9:45 pm #7

cant seem to find the post though. Fairly recent....

dr_subsonic's pneumatic research lab

the Lunatic Fringe of American Airgunning
Southwest Montana's headquarters for Airgunning Supremacy
Proud Sponsor of team_subsonic
The problem? Well, the clutch design in it, once set, would always prematurely release. No matter how it was set. Well, duh, it turns out that as pressure builds in an MSP the pressure acting on the piston surface builds! Who would have thought!?

Anyway, the best solution was to shorten an actual FX PCP pump. Got it down to draw 130cc of air. This little tube section will attach to the valve and the top will attach where the lever toggle pins. The end result? An on board PCP pump MSP. Again, here is the pump ready to go. The pump is two inches shorther than pictured (made a bo-bo and over measured on the outter tube - problem fixed now):



"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
Last edited by Duane30 on May 23rd, 2012, 9:47 pm, edited 1 time in total.
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Joined: April 28th, 2010, 12:23 am

May 23rd, 2012, 9:55 pm #8

...will still be the surface area of the largest piston diameter. The same end result if the design was just a large diameter piston the same diamter of the larger telescopic piston.

Once all the pistons have been collapsed, the piston is solid.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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Joined: April 23rd, 2012, 11:10 pm

May 24th, 2012, 12:06 am #9

...will still be the surface area of the largest piston diameter. The same end result if the design was just a large diameter piston the same diamter of the larger telescopic piston.

Once all the pistons have been collapsed, the piston is solid.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
The same end result if the design was just a large diameter piston the same diamter of the larger telescopic piston.
Depends. ( but definitely no IF the details get worked out )
As I alluded earlier, I haven't got the mechanics quite resolved, but it goes like this...

If the squish area is also matching concentric rings....
In other words, there are matching progressively smaller cylinders into which the telescoping piston parts travel. Probably opposite of what you're thinking based on the diagram.

The largest diameter compresses to its "shelf," reducing its squish to zero. At that point, the next smaller diameter continues to travel to its "shelf," further on in the stroke. So on and so on, until all that is left is the smallest diameter, proceeding to the valve inlet.
This way, as each larger diameter bottoms out, it effectively becomes the cylinder wall for the next smaller diameter, until the next smaller passes the shelf for the larger, at which point the shelf becomes the cylinder wall for that size, and the larger irrelevant, as it's now completely passed by the next smaller.
Spring pressure for the larger diameters needs to be higher than the highest expected cylinder pressure at that level of compression to insure the larger diameter ring in fact, bottoms on its self before the next inner diameter begins to move independently of the outer.

Minimum pumping effort would be the sum of all springs divided by mechanical advantage of the linkage.
Maximum effort would be determined by the highest expected PSI developed by the smallest diameter.
The smallest having no spring loading, and so being a direct mechanical connection to the pump linkage.
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Joined: April 1st, 2009, 3:18 am

May 24th, 2012, 12:06 am #10

Ya know, if the pistons can be designed to where they do not prematurely collapse in on themselves, the idea just may work. My logic came from the fact of friction. The piston design would in fact work on the open stroke as it should, but the concern comes from friction of the seals when closing. The friction would cause the pistons to simultaneously closed once closing movement began. Design around that, problem solved.

"The majority of things in our lives are created by folks no smarter than the rest. Afterall, the world is comprised, and operated by C average people intellctually, academically, and morally. These people are often the great pioneers that set the precedent for what excellence should be."
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