Posted by: admin

Great, let us know how the testing is going and where you buy the valves!

Hi , Plenty vendors sell V-grooved ball valves , haven't place a order with any at this stage.

https://www.bray.com/ball-valves/control-valves/advanced-v-control

https://whatisneedlerollerpin.com/2VULport+hollow+SS316-SS304+balls.htm

Don't know of any European suppliers that are closer to you.

I will be for the experimentation purposes  modifying a standard ball valve at work , turning and grinding spherical shapes with V grooves. Also cylindrical valve arrangement with a V groove is much easier to turn on a lathe/grind and mount into a housing.

I also thinking along the lines of a pintal orifice design a bit more work in concept.

At this stage my H&F GB4 dyno has a V-groove  cylindrical  valve arrangement similar to one of your websites pictures you posted on  http://yourdyno.com/brakeabsorber-dynos/

Bye

Eric91,

That's a lot of steps!! It will not work like you have set it up. You have 9700 steps between 0 brake and 100% brake, and max 2000 steps per second. So it is going to take about 5 seconds for the valve to go from 0 to 100% brake. That's way too slow. 

Can you configure your stepper controller to use 200 steps per rev, or is this set by your stepper motor? I would consider swapping out the motor if that is not possible. Also see if you can get a higher gearing such that the stepper does not need to go so many revs from min to max brake. 

My stepper driver have minimum 400 pulse/rev. I will try with 400pulse/rev, but valve from fully open to fully closed have almost 10 turns, 4000 steps. 2000 steps/second is the Maximum speed allowed?

PS i have nema 34 stepper motor. 

Sorry for banal request, but it's my first experience with stepper motors. 

Hi eric91  , what external Supply Voltage are you using to the nema 34 stepper motor ?

 I see that the MS_driver ST_M5045  can control a Vdc - 24V to 50Volts ,

I'm going to use this 4.5Nm Nema 34 1 Axis Stepper Motor & Driver ( https://www.ebay.com.au/itm/112373699571 ) or Stepper Kit 4.0Nm(566oz.in) Nema 24 Stepper Motor & Driver ( https://www.ebay.com.au/itm/172864922496 )  , I haven't yet decide which of the two but one has feedback ( for future upgrade potential !)  or even maybe smaller unit 3.0Nm Nema 23 Stepper Motor & Driver (  https://www.ebay.com.au/itm/171994207870 ) .

What size Nema stepper motor will do the job ? Don't know yet ?

Bye

Hi, I use 36v 5a external supplier for nema 34 engine. Look stepper online.com, have a lot of stepper Engines. I choose high torque nema 34 Motor because vmp valve have the resisteance of spring. With normal flow valve is necessary less torque.. 

Hi, today I have made some test with 400 pulse/rev and 1200 steps from 0% to 100% brake. I have reduce the stroke of the valve at about 3 turns, but the System is yet instable, I think I must find the correct value of kp and ki value. With kp 0.3 and ki 0 The System is instable. With kp 0.1 ki 0 System is quite stable but with some errors. Could you suggest me a  good brake curve to set pid controller? Thanks a lot

Eric

Hi, 

So you are getting closer to a good setup. It is still about 1.5 seconds from no brake to full brake, which is slow. If you are below 0.5 seconds, best to have below 0.5 seconds. You may add a gearing. 

Anyway, with slow valve control you need low Kp and Ki. It will still work but it means the regulator will be less able to adjust to sudden changes. 

Indeed any setup without Ki will have a static error, only Ki can fix that. You are on the right track, you can experiment a bit more with Kp and Ki, but better to increase the speed of the valve control.

Hi, 

Have you any suggest to gearing the Motor? Is not possible increase velocity by software or stepper driver? 

 QUOTE , " Member :  eric91- Hi, I use 36v 5a external supplier for nema 34 engine. Look stepper online.com, have a lot of stepper Engines. I choose high torque nema 34 Motor because vmp valve have the resisteance of spring. With normal flow valve is necessary less torque. "

Hi Eric, that is why I asked what voltage are you using to step your stepper motor.

quote, "Technical Parameter - ST-M5045 Micro-Stepping Stepper Motor Driver Supply Voltage: 24~50Volts DC & Output Current (peak): Min 1.0 Amps, max 4.2Amps"

My thinking is if the stepper motor driver can control 50 Volts DC maximum to the stepper motor that will give you more speed and torque than what will 30 volts DC going to the stepper motor. Is my thinking wrong ? OR right ?

Example - if you get a 12 volt wiper motor and supply it 12 Volts DC ( & pulling 4 amps approx with a load )  from a car battery charger it will spin nicely with plenty of speed & torque , then if  you change the voltage on the charger to 6 Volts DC it will slow down in speed and torque drops down considerably on the wiper motor.  Just my observation and thinking the same will apply to stepper motors and voltages supplied to them.

Sounds like I'm going to be faced with the same problem as from no load to full load is 14 approximately full turns of a shaft on the H&F hydraulic water brake dyno just to turn a cylindrical shaped V grooved valve to control the water outlet.

Post a few pictures of your dyno setup Eric please and thanks.

Bye

Hi, I think that the velocity of stepper motor is regulated only by stepper driver and software. Software have Maximum 2000steps/sec both at 24v and 50v. If you change volts or ampere, I think that change only the torque.

I think the better choice is to put  2 plastic gears between stepper Motor and flow valve. Is quite simple, the only problem can be the vibrations..

I have only few photos...now I upgrade the System with flow valve instead of vmp 12 spring valve, and works better.. 

Posted by: admin

Hi, 

So you are getting closer to a good setup. It is still about 1.5 seconds from no brake to full brake, which is slow. If you are below 0.5 seconds, best to have below 0.5 seconds. You may add a gearing. 

Anyway, with slow valve control you need low Kp and Ki. It will still work but it means the regulator will be less able to adjust to sudden changes. 

Indeed any setup with Ki will have a static error, only Ki can fix that. You are on the right track, you can experiment a bit more with Kp and Ki, but better to increase the speed of the valve control.

 

 

Hi jostein, 

I make some calculations, but If I havent make an error, with 1200steps from 0 to 100% with 400pulse/rev and 2000steps/sec the time necessary or valve to go from 0 to 100% it's about 0.6sec not 1.5sec

Infine i have bought 2 plastic gears (rs online) mod. 1, one 32theets and one 16theets, thus the transmission ratio between stepper motor and flow valve will be 0.5 and the velocity to go from 0% to 100% brake (4 turns) must be about 0.4sec (with 400pulse/rev and 2000step/sec)

Hi, yes you are right with regards to the speed. Anyway, if you drag the slider in the brake setup quickly from 0% to 100% brake, then you see how fast it is :-).

How is it working now? 

Next daysI will build a gear for stepper engine and I Will make some test! I will post here results, impressions and answers 😁

Thanks a lot

Eric