Hi, guys. I am making a low cost engine dyno. The loading is achieved by a hydraulic pump for which I vary the restriction of the oil flow. See video of it in action here: Now I want to change the manual restrictor/throttle valve that you see I am operating with an electrically controlled one. That way I can make control electronics that give an automatic sweep across the RPM range or make it locked at any (max) RPM for example. I have tried to search for such a valve but have not found one yet, or at least I am not sure. There are lots of valves out there, many different types and many of them with little information. I would be glad for some good pointers here! The engine has about 80 horsepower. Thanks for your help! Cheers, Jostein
Hi, I don't have a valve suggestion for you, but a reference which is relevant to the work you're doing. (hydrostatic dyno) They have a similar project at the University of Wisconsin's Powertrain Control Research Laboratory. http://powertrain.engr.wisc.edu/ For a bit of detail, click Research and then Transient dynamometer System Development. Be sure to also check out the Photos section - there is quite a bit of detail there. Best of luck on your project! Kevin
Can't watch your video at work so I don't know what kind of valve you're using now, but if the valve itself works why not just keep it and operate it with a gearmotor or other type of electrically controlled actuator?
Kevin, cool stuff you found at Wisconsin University! Dana, yes, I though about that. It is possible indeed. But I believe there are valves out there with the motor or actuator or whatever already in one package. That is what I am looking for first. Cheers, Jostein
There are a few techniques which work depending on whether you want to calibrate this as a dyno or just load the engine for testing purposes. I suggest not using a variable orifice but a proportional pressure relief valve cartridge. You can then set the blow-off pressure which will remain constant at variable flows at different rpm. The power draw can be estimated using P (pressure) x Q (flow) /600 = kW. If you have a fixed displacement pump the flow will be proportional to rpm, pressure is cheaply measured by gauge or electronically. If you wish to automate the process, pressure can be contolled and power draw can be programmed. If you don't want to calibrate the power draw then a cheap aluminium gear pump is ok, otherwise use a cast iron gear pump (Parker Hannafin have a suitable range) or axial piston pump which is more expensive. These are much more efficient and will give more accurate result. Suitable proportional cartridges are made by Hydraforce, available worldwide. Check their website. Last thing is keep temperature of oil 50-60C optimum. You will need a cooler with 100% engine power dissipation. At 60C an alli pump will run 85% efficient. Cast iron 90+% and an axial piston 95%+. Good luck.
ChrisW, thanks a lot for your input, just what I needed. I found a Hydraforce valve I think is suitable, the TS10-26 for example. I have a fixed displacement pump (cheap aluminium thing) but I only use it and the valve to retard the motor. I don't really care about the pressure (except for safety). The pump is mounted to a bearing so it can rotate, but is prevented from rotating by an arm hooked up to a load cell. Then I made electronics that read the load cell and the RPM, and feed it to the PC and from there I can draw the torque and HP curves. This should be accurate, apart from not accounting for the heat generated. Now I will expand the electronics to control the valve, and I should have an automatic sweep of the RPM range! Thanks, Jostein
Actually it does account for the heat, since you're measuring the torque on the motor shaft, before any heat losses in the pump. The heat is lost on the other side, so rpm x torque will give you the exact shaft horsepower.
Svinaldo, your setup is perfectly competent and should do the job well. Nice touch using the torque arm and load cell which can be accurately calibrated by deadweight. You are right Dana, the measurement is independent of the load system apart from possibly some non-linearity in the load as temperature in the system rises. Do remember that ALL the power output will be absorbed by the hydraulic system so the oil will receive 60kW input and temperature will rise very fast. 60C is a good maximum to aim for, 80-90C is sustainable by the system for brief periods but hazardous if you should contact it. By about 105C the oil has lost all lubricity and a seizure will follow! Take care!
I think this post will really help me and it is a beneficial post for all those who are looking to work using hydraulic restrictor or valve. But I still have few question in my mind can I ask you? Like if I what to make a dumping machine what kind of hydraulic system I can use in that.
This is very nice post i m very like it and i appreciate you for good work keep it up it is very useful for me..
