| 主权项 |
1. A steering system configured for attachment to a steering wheel, the steering system comprising:
a fluid motor; a steering unit configured for receiving and expelling fluid; wherein the steering unit is in fluid communication with the fluid motor, the steering unit including:
a fluid meter configured to meter fluid to the fluid motor in response to actuation of the steering unit;a valve housing in fluid communication with the fluid meter, the valve housing defining a valve bore; anda valve assembly disposed in the valve bore and configured for receiving an input from the steering wheel;wherein the valve assembly is moveable between a first open position and a second open position;wherein the valve assembly defines a first variable orifice, a second variable orifice, a third variable orifice, and a fourth variable orifice on a primary fluid path to the fluid meter and to the fluid motor from the fluid meter;wherein the valve assembly further defines the first variable orifice, the fourth variable orifice, and a bypass orifice on a secondary fluid path to the fluid motor, that bypasses the fluid meter;wherein the valve assembly includes:
a sleeve defining a bore; anda spool disposed in the bore of the sleeve;wherein the sleeve and the spool cooperate to define the bypass orifice;wherein the sleeve and the spool extend about a central longitudinal axis and the spool is configured to rotate about the central longitudinal axis, relative to the sleeve, such that the spool is rotationally displaced, relative to the sleeve, about the central longitudinal axis in response to receiving input from the steering wheel; andwherein the valve assembly moves between the first open position and the second open position in response to an amount of rotational displacement between the spool and the sleeve;wherein the bypass orifice is open when the valve assembly is in the first open position such that the secondary fluid path is open and fluid is permitted to flow through each of the primary fluid path and the secondary fluid path;wherein the amount of rotational displacement between the spool and the sleeve is less than or equal to 5 degrees when the valve assembly is in the first open position;wherein the amount of rotational displacement between the spool and the sleeve is greater than 5 degrees when the valve assembly is in the second open position;wherein fluid flows through the secondary fluid path in response to input from the steering wheel, as a function of a volumetric inefficiency of the fluid motor; andwherein the bypass orifice is closed when the valve assembly is in the second open position such that the secondary fluid path is closed and fluid is permitted to flow through the primary fluid path and fluid is not permitted to flow through the secondary fluid path. |
