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Characteristic features

• No bearings in the piston actuating mechanism:

The most significant difference to all other piston machines is the absence of any bearing in the power train (between the pistons and a drive shaft). Piston forces are transformed in a torque without using a single bearing transmitting piston forces. Therefore, the pistons can be enlarged to any size at any pressure. Piston forces are not more restricted by the limitations of bearings. (The drive shaft is axially balanced.)

• Kinematic and work process are unique:

A bearing-less piston actuating mechanism with only rotating pistons generates a relative stroke motion between pistons and cylinders without mass forces normally belonging to it. It is the best kinematic possible.

The pistons, passing over the inlet port, suck in and push to the same time backwards against the high working pressure in the housing. That`s basically the entire pump-process. On the other half of one revolution the pistons have nothing to do anymore. They could be taken out for this time period. (They are not air-tight in this phase.) All what they do is moving in the start position for the next working phase.

This new work process has numerous dramatic consequences. Piston forces can be totally balanced. Furthermore, the "compression phase" in the cylinder is eliminated, that means a fluid-gas mixture can be pumped - even against high pressure. Gas can be compressed almost as high as fluid pressure.

• Most complete balance of all forces:

Oscillating mass forces are not present. Both rotors revolve around the centers of gravity.

The cylinder block is hydraulically balanced by funneling high pressure under the cylinders which are partially closed for this purpose.
The drive shaft, piston plate, and pistons are one piece and are axially balanced by making the area content of the cross section of the drive shaft (on the shaft seal) equal to the sum of all active piston areas. The hydraulic forces on the pistons and on the drive shaft compensate each other in axial direction, because the pistons are pushing backwards.

• Total oil-free operation for pumps, compressors, water hydraulic motors etc.

Friction is dramatically minimized that this rotary piston machine is able to run without any lubrication - even at high pressure, high volume and high speed.

• Largest range in volume and pressure:

The Wolfhart Principle has no limitations in the possible range of volume and pressure. The product "volume times pressure" is the highest. There are principles for high volume and others for high pressure; this principle can both at the same time. A typical application may a water pump for 1000 GPM at 1000 PSI, where no other principle is suitable.

• Largest range of speed:

Some principles must run with a minimum speed, some are not able to run fast. This principle can both. The kinematic of this machine has no limitations. (The maximal speed will determined by other parameters like the viscosity of the medium etc.)

• Highest possible efficiency:

Low friction, low acceleration of the fluid, and large ports etc are the means for a smooth operation and a high efficiency. The tests show that this new principle has the highest possible efficiency. (Test data are available.)

• No lateral forces between pistons and cylinders:

The connecting rods are screwed on the piston plate with an specific angle that in the working phase of the stroke motion the connecting rods are straitened in the cylinders and lateral forces minimized. A certain overcompensation drives the cylinder block. That means the cylinder rotor is hydraulically driven.

• Highest possible durability:

Simplicity breeds Durability. This simplest piston principle has also the highest durability.
If foreign particles are coming in, the cylinder block is able to lift up from the valve plate. The piston sealing elements are also hold in place only by a spring. They can actually stop moving in the cylinders until the particle is gone.
If one connecting rod should break, the piston remains on the ground of the cylinder and the pump is still running generating pressure.

• High live expectancy:

No bearing is better than the best bearing. If the piston plate is directly attached to the shaft of an electrical motor, the entire pump has no bearing. The remaining wear on cylinder block and pistons is minimized by eliminating of unnecessary contact pressure.
The cylinder block is hydraulically adjusted for a minimum of contact pressure.
The spring-load of the piston rings is about 10 times lower compared with conventional piston pumps allowing a small leakage, but a much greater live span.

• Disadvantages of this new principle:

It is unknown and not on the market

To the theory:

The inventor found by an mathematical analysis a "magic angle" of 5° for the inclination angle between both rotors which opens up enough volume, while the distortions, caused by the inclination angle, are still insignificant. This is the base of this invention.

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