Hydraulic Motor design

[ecope]

Hello, I am needing to design a hydraulic motor (don't ask why I cannot just go buy one). Is there any information on the internet or books for designing the motor?

Thanks!

 

[hydtools]

None that I have found. We had our own proprietary design for a gear motor. You will find general information on principles of operation, but not specific design information. Manufacturers keep their design details in-house. You may use Nichols gerotor elements in a housing you design according to their guidelines. You then design the shaft and shaft sealing to meet your requirements.

Ted

 

[EdDanzer]

What type of motor are you trying to design piston, gear or gerotor, high speed or low speed? What is the application?

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[budt]

A company I worked for that manufatured cylinders had several in house Internal and External Hones to hone the cylinder tubing and Piston Rod mateial.

Somebody came up with the bright idea to drive one of the hones with (3) Double Acting Hydraulic Cylinders positioned radially around and driving a Crankshaft. Each one had a 4-Way Directonal Control Valve that were controlled by Limit Switches on a Cam that shifted the valves to make the cylinders push or pull as the Hone turned.

The hone turned at about 150 RPM and honed cylinder tubing up to 16" Dia.

The other function of the drive was to test new ideas on cylinder design amd material since many cycles were put on the cylinders quickly at (3) shifts a day 5 days a week.


Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING

 

[ecope]

The type of motor would be a gerotor, low speed, high torque and the application would be turning a special roller at different speeds.

 

[hydromech]

I wont ask why you cannot just go out and buy a motor, but I will say that you should do it.

It is much easier to buy a motor that has a torque output that matches your requirements than it would be to design one.

To design a rotor form that gives the torque and displacement you require would be tricky to say the least.

The distributor valve design and manufacture would be equally tricky.

You could spend thousands and take several years to design the perfect motor to suit your application, then find one with exactly the same performance at your local motor stockist.

All of the above excludes work on castings, shafts and shaft seals...etc.

Adrian

 

[hydtools]

Making a motor using Nichols gerotor elements isn't that tough. We machined housings out of aluminum stock. We hard anodized them for wear. Parker/Nichols provides the dimensions and tolerances for their gerotor element sets. There are no distributor valves, you machine the ports into the housing. The center of rotation is the same as the ouput shaft center so you don't have the 'dog bone' connector. The center gerotor gear directly drives the ouput shaft. You decide on how you want to support the output shaft and you decide how you want to seal the shaft. You decide how you want to mount the motor; even to making it intergral to the whole product.

No, I don't work for Parker. I have used their gerotor elements in product design.

http://www.parker.com/nichport/development.asp

Ted

 

[hydromech]

hydtools...


Could you give more details about the porting in these motors?

I cannot see how, through static ports in the housing, the oil can be fed into a moving rotor set and still keep the set turning.

Thanks

Adrian

 

[hydtools]

The gear set does not nutate like the gear set in an orbiting gerotor motor. The gear set rotates about a fixed axis, therefore the increasing and decreasing volumes between the inner and outer gears is stationary similar to the operation of two external gears in a gear motor. The ports are static since the increasing and decreasing volumes don't move relative to the motor housing. Imagine running an internal/external gear set. The inside(external tooth gear) gear rotates about its axis while the ouside (internal tooth gear) gear rotates about its axis. The eccentricity makes the motor work. The gear teeth have minimal clearance 180-deg from their mesh position. This creates the working volumes of the motor.

The key is the gear set rotates around a fixed axis. It doesn't orbit around the fixed axis. Therfore you can use static ports and do not need the rotating valve or the intermediate drive connector to the ouput shaft. It is an internal/external gear version of the external/external gear set.

Ted

 

[hydtools]

Go to this link to see the illustration of the gear set operation.

http://www.parker.com/ead/cm2.asp?cmid=8954

Ted

 

[EdDanzer]

Using a gerotor is the manner shown in your link will be a high speed motor, not a low speed high torque motor like a CharLynn, Ross or White. If the geroter runs around the ring you get a reduction and this requires a rotary valve. Low speed high torque gerotor motors have pressure and speed limits that are in part from the valve operation. The Parker catalog shows the operating speeds of HPI Nichols motors and their low speed high torque geroter motors and there is a significant difference.
If you must build a motor start with a 2000, 4000, 6,000 or 10,000 series bearing less Charlynn, purchase their soft splined shaft and go from there.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[hydtools]

Yes, the non-orbiting design is used for high speeds. But they are also used for low speeds.

Now the design work begins knowing the variations available. Determine the speeds and torque required. Sort through the motor displacements for the required performance. Determine hydraulic flows and pressure, the hydraulic system already exists. The motor may be an orbiting gerotor or non-orbiting gerotor. The catalog will help by giving data against which the requirements can be compared.

Only ecope can decide.

Ted