Motor vehicles – Including one or more ski-like or runner members – With at least one surface-engaging propulsion element
Patent
1993-02-09
1994-06-21
Focarino, Margaret A.
Motor vehicles
Including one or more ski-like or runner members
With at least one surface-engaging propulsion element
180132, 91401, 92 135, 92 138, B62D 512, B62D 908
Patent
active
053221427
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a hydraulic auxiliary power steering, especially for motor vehicles, with a working piston that can be shifted in a housing on a threaded spindle and a steering valve that--as a function of the steering direction--directs pressure oil into one of the working chambers of the working piston. The working piston has an axial borehole in which--on both sides of the borehole outlet--sit turnoff valves whose plungers stick out of the working piston. To turn the auxiliary power off in the two steering deflection positions, the plungers run against stops inserted in radial walls of the housing. During the initial assembly, these stops can automatically, by means of the working piston, be pressed into the exact activation position in which the wheels reach the terminal stops.
Such a steering device is known from PCT publication WO 89/07064. There, the stops, made as sleeves, sit in boreholes of the radial housing walls, that is to say, the stops can be taken out only after the steering has been dismantled. Because the stops, following steering assembly, during the first steering action, are forced over the entire steering deflection to a press-in degree coordinated with the wheel stops, the steering can no longer be tested over the entire stroke range of the working cylinder without in the process altering the steering limitation setting. This means that the stops, which are movable for setting purposes must, after an examination, be pressed back into the starting position over the entire piston stroke by the pertinent housing drill holes, in other words, from the outside, so that they may subsequently once again be set by steering against the wheel stops. A new setting of the steering limitation can under certain circumstances also be required at the customer's end if the vehicle maker did the wrong setting.
The purpose of the invention is so to improve the steering limitation that even subsequent setting changes can be done without any major assembly effort.
According to a first embodiment of the present invention, the stops, made as sleeves, sit on bolts that can be screwed into the housing walls. The combination, consisting of bolt and sleeve, can easily be preassembled outside the housing. Here, the permitted shifting force can be monitored much more easily between a minimum value and a maximum value. According to the state of the art, monitoring the shifting forces in housing parts of different size is much more difficult.
Using the improved steering limitation, the threading holes in the housing and in the lid of the working cylinder can first of all be closed off with normal screws, so that the entire stroke range of the working piston can be examined. After the end of the testing procedure, one screws the bolts in with the movable sleeve, one tests the tightness of the arrangement, and one subsequently sets the predetermined turnoff points by coupling the working piston. If the vehicle customer should find that the steering limitation was set erroneously, then the combination, consisting of bolt and sleeve, can be easily exchanged from the outside, or the sleeve can be newly set on the bolt outside the steering. One can thus avoid having to dismantle the steering. The structural components, that can be stuck upon each other, have a lesser weight and can therefore be handled easily.
According to a further embodiment of the present invention, one can make the bolts also as sleeves that can be screwed in and one can press the stops in the form of small pistons into the sleeves. Using this variant, one can achieve the same setting and assembly advantages as with the model according to the first embodiment of the present invention set forth above.
If, according to a further aspect of the present invention, one provides the seat of the stops (sleeves or small pistons) with ring-shaped bulges, then one can thus achieve an improvement in the adhesion friction.
According to a further aspect of the present invention, the small pistons of the variant reveal relief boreholes so that the pressu
REFERENCES:
patent: 4159723 (1979-07-01), Baatrup et al.
patent: 4773303 (1988-09-01), Stroud
patent: 5086864 (1992-02-01), Elser
Focarino Margaret A.
Mattix C.
Zalkind Albert M.
ZF Friedrichshafen AG.
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