| 摘要 |
<p>A servo-assisted steering system has a rotary gate valve composed of a rotary distributor (10) forming a single piece with the steering column (3) and a valve bush (20) forming a single piece with a threaded spindle (5). To carry away return oil for each direction of rotation, return bores (11-17) longitudinally arranged one after the other form two adjacent bore rows (9 or 9A). Each bore row (9 or 9A) is associated with a control groove (24 or 22) in the valve bush (20) linked to the working cylinder. The return bore (17) lies between the two bore rows (9 or 9A) and has an unvarying residual cross-section. To control the pressure increase, all return bores have in their active pressure chambers (30 or 31) flat control windows (51-57) of various circumferential lengths. The return cross-section created by the return bores can be changed by a driving piston (60) arranged in a concentric bore (45) of the rotary distributor (10). The driving piston (60) can be adjusted according to a driving speed dependent pressure. The change in cross-section of the bore rows (for example 9) that help control the pressure allows the actuating forces of the steering wheel to be adapted to each driving condition.</p> |
