| 摘要 |
The present invention includes one illustrative embodiment that relates to a system that includes a piston pump, an open center valve, and an electronic controller. The piston pump is configured to provide a pressurized flow, such as to the open center valve. The open center valve is fluidly coupled to the piston pump, and configured thereby to receive the pressurized flow from the piston pump. The electronic controller is electrically connected to the piston pump. The electronic controller is also configured to receive operator input and to electronically control the piston pump, responsively to the input, to provide the pressurized flow to the first open center valve at a flow rate that is selectable from a range that is continuously variable from zero flow to a preselected maximum. Additional embodiments include, for example, a means for electronically controlling the piston pump, or a power machine with a frame, ground engaging members, and an engine. Among other advantages, embodiments offer continuous variability of flow rates, thereby improving cycle times and allowing selectable flow to a given attachment, for example. The flow can also be reduced to zero when there are no functions demanding it, thereby saving power and improving cooling, and the piston pump may be controlled electronically instead of with load sense signals, among additional advantages in various embodiments.
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