Abstract
Within hydraulic axial piston machines, critical components experience centrifugal forces, which can limit the performance of the actual machine. Often, this results in tipping of the cylinder block or barrel, causing friction in the barrel-port plate interface and affecting the efficiency and durability of the machine. In a hydraulic machine based on the floating cup technology, such as pumps, motors, and hydraulic transformers, the centrifugal force experienced by the cups is counteracted by the fixed pistons. The combined reaction forces on the cups cause a tipping torque on the barrel plate. Although a hydrostatic trust bearing can be used to compensate for such tipping, the effectiveness of the bearing depends on the pressure within the system and is limited in the amount of torque it can compensate for. This solution is sufficient for machines up to a certain size and a maximal rotational speed. However, if the machine requirements exceed these limits, a different solution is needed.
Ideally, the centrifugal forces on the cups are counteracted by the barrel plate, since it rotates around the same axis as the cups. This can be realized by introducing an opposite force using counterweights connected to the barrel plate. The centrifugal force on the counterweight is redirected via a lever to counteract the centrifugal force on the cup, minimizing the interaction between the cup and piston. As a result, the barrel plate tipping torque is diminished, decreasing the friction between the barrel plate and the port plate, which in turn results in an increase in efficiency and durability of the machine. The new solution also creates the opportunity to further increase the maximum rotational speed. This is especially important for electro-hydraulic actuators and hydraulic transformers.
