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Old 05-01-2010, 10:14 PM   #1
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Default A simple electronic RPM based actuator?

I've been churning a secret squirrel idea in my head for a couple weeks now. I need some sort of actuator to make my idea work though. I need something that can adjust angle (spin) or length based on RPM. As an example, VVT adjusts angle based on RPM - but it's much too complicated for my particular use. Are there any examples of simple motors/actuators/etc that I can use and control with an aftermarket ECU? It's probably out there plain as day, but I can't think of anything.

Thanks!
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Old 05-01-2010, 10:27 PM   #2
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so you need a variable output instead of just an on off at a certian rpm? You may be able to build some circuit based on the pwm of the injector channel. im pretty sure the water meth circuit works off of pwm based on rpm in megasquirt.
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Old 05-01-2010, 10:33 PM   #3
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yes, on/off would make it pointless

I'm running a hydra, so I can run it from it's own PWM.
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Old 05-01-2010, 10:52 PM   #4
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Stepper motor w/ driver circuit?
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Old 05-01-2010, 11:08 PM   #5
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never heard of a stepper motor, but looked it up, and it could very well work. Also gave me the idea to use some sort of servo...I've got a very nice RC car - why didn't i think of that!?!?...

So I wiki'd "servo"...

RC servos are composed of an electric motor mechanically linked to a potentiometer. Pulse-width modulation (PWM) signals sent to the servo are translated into position commands by electronics inside the servo. When the servo is commanded to rotate, the motor is powered until the potentiometer reaches the value corresponding to the commanded position.

Now I'm trying to find a larger than RC, high torque servo!!
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Old 05-01-2010, 11:16 PM   #6
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How much torque do you need? RC servos are made pretty big.
http://www3.towerhobbies.com/cgi-bin...&I=LXGLN4&P=ML
152 oz/in

http://www3.towerhobbies.com/cgi-bin...?&I=LXAAD4&P=7
292 oz/in
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Old 05-01-2010, 11:27 PM   #7
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292 oz/in = 1.52 ft-lbs?

i was thinking 10 ft/lbs or so would be fantastic, maybe overkill, but not sure yet.

i keep looking, and it seems like servo motors go from RC applications at under $100 to industrial size/industrial cost systems, which are ridiculously oversized. Seems like they would make something appropriate for robotics, but having trouble finding it. I'll keep looking tomorrow, but really have to go to bed now
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Old 05-01-2010, 11:57 PM   #8
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Why not use a solenoid and Hydra's electronic boost control? I haven't used Hydra, but it's pretty standard protocol to allow boost per rpm.
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Old 05-02-2010, 12:33 AM   #9
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Quote:
Originally Posted by fooger03 View Post
Now I'm trying to find a larger than RC, high torque servo!!
These guys rock: http://servocity.com/

Specifically, they have big linear servos (up to 115 lbs thrust): http://servocity.com/html/linear_servos.html
and massive, mega-torque rotational servos: http://servocity.com/html/robotzone_servos.html

4,995 in/oz enough for you? (That's 26 ft/lbs.)




Also various servo controllers:
http://servocity.com/html/servo_controllers.html
http://servocity.com/html/dual_servo_driver.html



Just make sure that your ECU will generate a variable duty-cycle PWM signal at a fixed frequency, and you're golden.
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Old 05-02-2010, 08:20 AM   #10
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Quote:
Originally Posted by Joe Perez View Post
These guys rock: http://servocity.com/

Specifically, they have big linear servos (up to 115 lbs thrust): http://servocity.com/html/linear_servos.html
and massive, mega-torque rotational servos: http://servocity.com/html/robotzone_servos.html

4,995 in/oz enough for you? (That's 26 ft/lbs.)




Also various servo controllers:
http://servocity.com/html/servo_controllers.html
http://servocity.com/html/dual_servo_driver.html



Just make sure that your ECU will generate a variable duty-cycle PWM signal at a fixed frequency, and you're golden.
You, Sir, are my hero
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Old 05-02-2010, 12:13 PM   #11
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What are you trying to do? Make an adjustable rear wing?
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Old 05-02-2010, 12:30 PM   #12
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adjustable length intake manifold.....
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Old 05-02-2010, 12:34 PM   #13
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interesting
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Old 05-02-2010, 12:52 PM   #14
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I've got 2 designs floating around in my head with the idea of maximizing helmholtz resonance across the entire RPM range by adjusting the length of the runners as engine speed varies.

I wish I had an ME degree

I wish I had a machine shop

I wish I had welding experience
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Old 05-02-2010, 01:35 PM   #15
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Trombone
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Old 05-02-2010, 01:59 PM   #16
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Thats 1 of the 2
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Old 05-02-2010, 02:08 PM   #17
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Quote:
Originally Posted by fooger03 View Post
I've got 2 designs floating around in my head with the idea of maximizing helmholtz resonance across the entire RPM range by adjusting the length of the runners as engine speed varies.

I wish I had an ME degree

I wish I had a machine shop

I wish I had welding experience
I know...thats why I went back to school to be a machinist.Now I have 2 out of the 3 and I know about30 people with the 3rd.Good luck with the design...thata what I thought you were going to build.
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Old 05-02-2010, 02:12 PM   #18
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Quote:
Originally Posted by fooger03 View Post
I've got 2 designs floating around in my head with the idea of maximizing helmholtz resonance across the entire RPM range by adjusting the length of the runners as engine speed varies.
Depending on what you are doing maybe you could retrofit components from a variable length runner setup from a bike, like a Yamaha R6.
http://www.sportrider.com/bikes/146_.../photo_02.html
I'll bet that it would be really expensive to get a used one though since that particular feature has not been out for long. Sportbike tech wars, gotta love it.
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Old 05-02-2010, 02:27 PM   #19
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Quote:
Originally Posted by ZX-Tex View Post
Depending on what you are doing maybe you could retrofit components from a variable length runner setup from a bike, like a Yamaha R6.
http://www.sportrider.com/bikes/146_.../photo_02.html
I'll bet that it would be really expensive to get a used one though since that particular feature has not been out for long. Sportbike tech wars, gotta love it.
My best friend and I track motorcycles, we learned about that system when they were coming out with it. It's a fantastic concept, and achieves a similar thing to what the 99-00 VICS achieves by changing the dynamics of the resonance chamber to accomodate two seperate focused RPM ranges (although I suspect the YZF does a MUCH better job at it.) Ideally, I would like to be able to tune such that the intake runner length is "infinitely" adjustable between the maximum length (Idle) and minimum length (8k rpms) so that at any given RPM, the intake runners are tuned for that engine speed.
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Old 05-02-2010, 07:53 PM   #20
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On our honda outboard motors BF225A 4 strokes they have a dual stage intake manifold. It works off a vacuum pot, Changes the intake from long runner to open chamber as the rpms increase. I believe the engine is a v6 originally from a honda CRV. They also have VTEC. I think somewhere online honda has a video describing this. Dunno if this helps but it was very interesting when I went to school for them.
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