Two speed gerotor motor

摘要

A two-speed gerotor motor of the type having a stationary valve member (19) defining a plurality of stationary valve passages, each including an upstream passage portion for commutating fluid communication with a moveable valve member (43), and a downstream passage portion in continuous fluid communication with a volume chamber (33) of the gerotor gear set. In some of the stationary valve passages (113), the upstream (115) and downstream (117) passage portions are blocked from direct fluid communication. A control valve spool (89) has a first position (FIG. 8) permitting unrestricted fluid communication between the upstream and downstream passage portions, for normal low-speed operation. The control valve spool has a second position (FIG. 9) blocking communication between the upstream (115) and downstream (117) passage portions, and connecting all of the downstream portions together, communicating with a fluid accumulation region (91), such that fluid from those volume chambers recirculates, to provide a high-speed mode of operation.