What kind of motor is used in syringe pumps?

[hanson]

What does it take to manufacture such a syringe pump?
What kind of motor is usually used in these systems?
http://www.macros.com.tw/p_kds.asp

 

[hanson]

can we see it better in this picture?
http://www.syringepump.com/oem.htm

 

[mgb_phys]

Usually a stepper motor driving a lead screw.
You run the stepper from a simple clock circuit that provides a train of pulses to the stepper driver IC.

 

[hanson]

But how would one get that train of pulses?
And is there anything related to microprocessor?
(I am sorry. I am an idiot in electronics)

 

[mgb_phys]

You could just use a simple RC circuit and a stepper driver IC
Some example circuits here http://www.doc.ic.ac.uk/~ih/doc/stepper/control2/connect.html

In a real product you would probably use either a very simple micro (8051) or a PIC just because it is easier to use a single board across a range of products with different features and a micro is useful if you want to add things like a keypad or have accurately adjustable rates.

 

[hanson]

Thanks mgb_phys, regarding the "very simple micro (8051)", is there any good online introduction or tutorial that i could follow?

I think i would need a real product setting. Basically, I would like to reproduce the above micr-processer controlled syringe pump. Is it difficult to do so?

 

[mgb_phys]

Generally board level micros require you to buy a dev kit and programming hardware.
If you are doing large production runs it's worthwhile but if this is just a hobby/ptorotype project you might be better off with a Basic stamp. This is a single chip computer that runs BASIC and can control lots of things like stepper motors - you program it with a serial lead from your PC.
They are made by a few companies - see http://en.wikipedia.org/wiki/BASIC_Stamp
If you are in the UK these people are very helpful http://www.milinst.com/

The next step up if you want to do 'C' or assembler is a PIC - again a very simple single chip micro. http://en.wikipedia.org/wiki/PIC_microcontroller

Either way you will need a driver chip to control the stepper - the micro cannot drive the current needed for the motor directly.

 

[hanson]

Do you think a step motor will do?
I mean would it deliver reasonably smooth motion for my application?
And how much would you estimate the entire system to be?
I will need a prototype only.

 

[mgb_phys]

Stepper motors are typically 200 steps/revolution.
The lead screw would be perhaps 1/8inch (3mm) pitch so one step would be 1/100mm movement of the syringe. Max speed of the stepper is typically 1/second so you would only move the syringe 3mm/sec.

Advantage of a stepper is high torque - so no need for a gearbox, simple to drive.
Disadvantages - expensive, large and high peak current.

For a cheap product you could use a small DC motor and a gear box.
Put a slotted disc on the end of the lead screw and use a LED/photo-diode pair to count the rotation and control the speed and distance of the screw.

 

[FredGarvin]

McMaster-Carr has some nice little DC motors with step down gear boxes on them for a relatively cheap price:

24 VDC— Have sleeve bearings.
p/n: 6331K35 $59.93

 

[anju420]

i too m working on syringe pumps...I'll be using 3717 ICs to drive them...But how do i choose the right stepper motor. My specs are :1.8 degree, unipolar, hybrid stepper motor...200 steps/revolution...How do i decide on the rpm, torque, current/voltage rating? i'll be using a gear ratio of 1:120...n flow rate required is 0-10ml/hour.
I need help coz once i decide on the motor I can decide the Vmm for my IC.