A new project of a super compact open center valve with very low actuating torque, only 5 degrees of dead-zone, good proportionality, higher maximum flow and a huge lifespan. Up to 60 bar of pressure.
Thank you aonemarine,Motor is an outrunner 750Kv 25A.Pump is from "Vivoil oleodinamica Vivolo" an italian brand. Displacement is 0.25 cubic centimeters x rev.Bye...
Very nice work, where can i buy this valve? Or is it homemade? This pump I have too and I am very satisfied. 60 bar?? Oh what a tubing? When you send me some link I will be very happy. Thank you a lot
Thank you, this valve is part of a little serial production for me and some friends. If you are interested to purchase them, please contact me at cmp_79@hotmail.com.I will give you all the explanation and details you need.Tubes are in Rilsan, the diameter 4x2,5mm is given for 88Bar of burst pressure, the 5x3mm for 100Bar.Talk to you soon...
I like the super-short large-diameter brushless motor :) Open centre is great as long as you never have more than one function running at the same time. Are you planning to add more functions? The valve block looks like a 2-function block?
Hi YensR, when you need low rpm and high torque in a compact shape this kind of motors works very well. :)In the first photo you can see three valves (three functions), with servo installed only on one of them. Since the concept is modular, each valve is a separate part that has to be assembled sequentially at the side of the previous valve. You can assemble from 1 to 10 valves or more, at the extremity of the valve pack there are the inlet and the outlet connection flange in aluminium that you see. Since the assembly of the valve blocks is in line, the open center flow line is in a series configuration. Therefore the oil circulate through the open center only when all valves are closed simultaneously. After even only one of the valves is moved away from the center the system go up at full pressure set by the relief valve in the center of the test bench beside the pump. All valves/function are independent and simultaneously usable. So the motor start up without the load on the pump and temperature of oil and motor don't raise when the model is stationary, so you are saving energy. It's good in circuits with 1 function and in others with 10 functions. And if someone don't want the open center function, there is a little hole in the inlet flange that must be kept closed and the system became closed center.In my Cat 330 the functions are from 6 to a maximum of 9 with bucket change and demolition claw. In a small scale production series i built 100 valves for me and some friends. :)
Very interesting, although I am not sure how you have managed to switch from OC to CC so seamlessly. Usually, with OC, your system pressure is the load pressure plus the pressure drop across the valve, which means that the system pressure is variable and hence one function's load state will affect the other functions. But I guess that's your trade secret ;)
Ho YensR,To switch from OC to CC I have to change the aluminium inlet flange of the distributor with another that don't have the hole for the OC, so it's not a thing you can do 10 times a day with the touch of a finger, but you can freely choose between OC and CC before you install the valves on the model."Usually, with OC, your system pressure is the load pressure plus the pressure drop across the valve, which means that the system pressure is variable and hence one function's load state will affect the other functions."This is true for CC too.When you turn five degrees a valve, don't matter wich, the system behavior became exactly the same of CC and the load/speed of a function affect the others (due to the pressure drop) depending of the oil flow from the pump. If you want to eliminate the pressure drop and so the interdependance of the functions you have to increase the flow from the pump a lot, but it can be done. All the valves are independant means that, apart from the open center circuit in series, the valves are in parallel configuration. If you burn a servo you loose only the function of the correspondant valve. And there is'nt a valve electronically piloted to close the center; the center close mechanically.There is no secret, it's an OC like the common industrial design.
why does the pressure rice to near maximum when there are no load at the cylinder, apart for some internal friction? Pressure loss in hoses, valve, filter?
Hi Rimrock,when you start moving the stick and hence rotating the valve, after 5 degrees the center circuit became close and the oil flow from the pump is sent back to the tank, flowing through the valve of maximum pressure. Immediatly after the center is closed, if you move the stick further, the rotation of the valve open the circuit to the cylinder wich start to move slowly and, beeing the oil flow very little, the pressure remain at the max value. From this point the behavior of the system is exacly the same of a closed-center valve: while the cylinder is moving, the more you open the valve and the lower the flow from the pump, the more is the pressure drop in the system.
Hello Erik79, I am very interested in the way you have the three hydraulic valves arranged in an OC series configuration. Do you operate all three functions (valves) at the same time? If you operate the first valve closest to the pump supply will the other valves work while that valve is not bypassing the fluid? If so how are you achieving the flow to the other valves? I thought about putting a pilot controlled flow control valve at the return end of the open center flow so all valves can work at the same time while there is a slight pressure fed to the flow control pilot valve as long as one of the three function valves is activated. In essence I'm trying to think of a full-time oc setup with all valves being able to operate as needed. As soon as the last valve in motion is moved back to center the pilot looses pressure and the oc return line opens reducing the system pressure. Would you mind sharing your hydraulic valve diagram with me? Perhaps even the CAD drawing so I can fully understand your layout. Any help would be greatly appreciated. Thank you.
Hi Jeremy, nice to meet you. My system allows you to move all the actuators connected to valves in a total independent way (being true that the pump has the ability to provide enough flow, of course). The OC layout is made in a way that the center line is open only when all the valves are in the center position. This is done by a non-conventional layout that i cannot share. So when you turn slightly one of the valves the center circuit became closed and the right amount of oil flow is provided by the pump controlled by a radio mixing. The pump rotates at an idle speed when the system is still and so the center is open. When at work the pump RPM increases in proportion with the sum of the aperture of the valves, providing the needed oil flow and minimizing the waste troughout the pressure release valve. Playing with pump displacement, motor RPM, valves flow and radio mixing you can customize the behaviour of excavator, finding the best balance between speed of movements, force, autonomy, and load sensitivity. See my video of the CAT365 at Bologna.See you!
Ciao Andrea, che fai, mi scrivi in inglese? Ha haa.... Il giunto motore - pompa è auto costruito per essere super compatto. Il lato motore ha due spine di trascinamento di acciaio che si inseriscono in due fori sul lato pompa con interposti due gommini morbidi. Il tutto è poi montato allineato entro un decimo.
Hello Friend, how are you? Would you like to know if you make these pieces to sell? I need a 4-way valve, this model of yours seems to me to be the best.
Hello Caetano, i'm fine. Nice to meet you, where are you from?Please contact me at cmp_79@hotmail.com I will give you all the information you need about these valves, ok?
