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In 2001, INNAS introduced the ‘Shuttle’ technology for noise reduction and efficiency improvement of hydrostatic machines. The current study revisits this technology for application in hydrostatic pumps and motors. In many hydrostatic pumps and motors, commutation is imposed by a fixed component like a valve plate. Designing a valve plate (or comparable component) that ensures good commutation at one specific operating condition, is fairly simple. However, an inherent problem of such a component is that it should ensure good commutation at all of the operating conditions. In an attempt to minimise losses and reduce noise emission caused by improper commutation, so-called shuttles were introduced by INNAS in 2001. These shuttles act as small pistons between two working chambers, essentially providing a connection to the ports while the valve plate is still closed. In theory, this will result in a check-valve like commutation. In the original paper, shuttles were implemented in a hydraulic transformer. This paper discusses and analyses the use of shuttles in pumps and motors. Simulation results show that the introduction of shuttles can reduce commutation losses to negligible levels. Furthermore, the results suggest that the use of shuttles could also reduce noise emissions. |
