[Diy_efi] RE: [offlist] Strain gauge on engine mounts

Wed Apr 20 21:50:55 UTC 2005

Hugh,
I'm with you on this...
Ernie B.
----- Original Message ----- 
From: "Hugh Keir" <hugh at sol.co.uk>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, April 20, 2005 10:56 AM
Subject: Re: [Diy_efi] RE: [offlist] Strain gauge on engine mounts


> Seems to me that the engine mounting rubbers will move in much the same 
> way that the prop shaft will twist.
>
> Why is the potentiometer / strain gauge from the inner wing to the engine 
> cam / rocker cover not just as good and a whole lot simpler to read?
>
> Hugh
>
>
> ----- Original Message ----- 
> From: "Marc Reviel" <marc at powerlogix.com>
> To: <diy_efi at diy-efi.org>
> Sent: Wednesday, April 20, 2005 5:33 PM
> Subject: [Diy_efi] RE: [offlist] Strain gauge on engine mounts
>
>
>> One good thing about using rubber is it's easy to "calibrate" on the 
>> bench - just put a known torque on it and measure the twist. Not 
>> super-accurate, but probably get within a few % of actual. Can also 
>> correlate the torque curve of this to a real chassis dyno. I do think the 
>> same thing can be done replacing the rubber with the driveshaft. In any 
>> case, the only real challenge is getting the sensors rigidly mounted, and 
>> to where they float with any shaft/coupler movement.
>>
>>
>> -Marc
>>
>>
>>
>> At 11:03 PM +0800 4/20/05, niche at iinet.net.au wrote:
>>>At 07:51 AM 20/04/05, you wrote:
>>>>Not sure that is such a good idea Mike ... the rubber is non
>>>>linear ... just like the mounts would be, and resolving the
>>>>edges requires some very fast counters at high speed and
>>>>quite big counters at low speed ... plus who wants that much
>>>>slop in the drivetrain ... it's not like you can swap this
>>>>thing in and out all that easily is it?
>>>
>>>Interesting point, think I misread this initially too, way too
>>>many mailboxes here...
>>>
>>>I think it should be possible to do this without any rubber,
>>>and avoid any drivetrain slop and be fully differential
>>>in respect of drivetrain lateral or even axial motion... !
>>>
>>>I mean, consider this:-
>>>
>>>a.   Toothed ring gear (pitch to be determined) on tail shaft
>>>       close as possible to universal joint, firmly attached
>>>
>>>b.   Second toothed ring gear as above but at furthest other
>>>      end so max length of tailshaft between gears
>>>
>>>c.   Tailshaft balanced appropriately
>>>
>>>Question arises, would there be enough twist of the tailshaft
>>>over the most appropriate length for the dynamic range of
>>>torque measurement needed ?
>>>
>>>ie. At lowest extreme the tailshaft twist may be so low that
>>>there wont be much discernible phase shift for a coarse
>>>pitch ring gear.
>>>At highest extreme it may well skip a cycle if too fine pitch,
>>>so a sync method would be needed if one is interested in
>>>wide dynamic range - which obviously is fairly easy to implement...
>>>
>>>Any mech structural engineers here care to estimate degrees
>>>of twist for say 100 newton metres of torque over length of say
>>>650mm and 80mm dia... ?
>>>
>>>
>>>>Regards from
>>>>
>>>>
>>>>Mike Massen
>>>>Perth, Western Australia
>>>>VL Commodore Fuse Rail that wont warp or melt !
>>>>http://niche.iinet.net.au
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>>Cheers
>>>>Rod
>>>>
>>>>-----Original Message-----
>>>>From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
>>>>Behalf Of niche at iinet.net.au
>>>>Sent: Tuesday, April 19, 2005 11:13 AM
>>>>To: diy_efi at diy-efi.org
>>>>Subject: RE: [Diy_efi] Strain gauge on engine mounts
>>>>
>>>>
>>>>At 01:51 AM 20/04/05, you wrote:
>>>>>Anyone ever done or considered doing a simple DIY driveshaft torque 
>>>>>design?
>>>>Heavy rubber coupler with two multi-toothed rings around each end, two
>>>>sensors mounted to display phase difference as torque increases?
>>>>
>>>>Now thats a good idea, far easier than the method in the link just 
>>>>posted,
>>>>probably be a lot cheaper too,  makes an inherent lot of sense, use an
>>>>all digital method  overall.
>>>>
>>>>There was a poster before who suggested something similar, use ABS
>>>>type pickup, think I misread that, thinking he was using only one, but 
>>>>of
>>>>course logical and clever to use two and look for phase difference.
>>>>
>>>>mmmm, Think I'll take a closer look under my car next chance I get
>>>>
>>>>Thanks for that,
>>>>
>>>>:o)
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>>Dealing with nonlinearities of rubber engine mounts (amoung other
>>>>>>things) is asking for trouble (as in huge wasted time relearning
>>>>>>whats already been arrived at), far far more direct, efficient, 
>>>>>>effective
>>>>>>and less invasive to measure the twist of the tailshaft :o)
>>>>>>
>>>>>>Regards from
>>>>>>
>>>>>>
>>>>>>Mike Massen
>>>>>>Perth, Western Australia
>>>>>>VL Commodore Fuse Rail that wont warp or melt !
>>>>>>http://niche.iinet.net.au
>>>>>
>>>>>--
>>>>>Marc Reviel
>>>>>
>>>>>PowerLogix
>>>>>http://www.powerlogix.com
>>>>>_______________________________________________
>>>>
>>>>_______________________________________________
>>>>Diy_efi mailing list
>>>>Diy_efi at diy-efi.org
>>>>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>
>>>Regards from
>>>
>>>
>>>Mike Massen
>>>Perth, Western Australia
>>>VL Commodore Fuse Rail that wont warp or melt !
>>>http://niche.iinet.net.au
>>>
>>>_______________________________________________
>>>Diy_efi mailing list
>>>Diy_efi at diy-efi.org
>>>http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>
>>
>> -- 
>> Marc Reviel
>>
>> PowerLogix
>> http://www.powerlogix.com
>> _______________________________________________
>> Diy_efi mailing list
>> Diy_efi at diy-efi.org
>> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>
>
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>