Lubrication – Systems – For chassis lubrication
Reexamination Certificate
2000-02-29
2001-08-21
Hepperle, Stephen M. (Department: 3753)
Lubrication
Systems
For chassis lubrication
C137S501000, C137S503000
Reexamination Certificate
active
06276491
ABSTRACT:
DESCRIPTION
The invention relates to a controller for controlling a medium flow fed to at least one hydrostatic or aerostatic pocket of a bearing, a threaded spindle nut or a guide, in accordance with the preamble of claim
1
.
Controllers of the type addressed here are known for liquids (DE 35 33 037 C1). They are distinguished by the fact that the fluid flow influenced by the controller increases in the event of a pressure rise in the hydrostatic pocket. Hydrostatic bearings, threaded spindle nuts or guides which cooperate with controllers of the above-named type are distinguished on the basis of this in that the achievable stiffnesses and loadings of these elements are substantially higher in the case of comparable technical data than those with alternative systems. The flow rate Q is proportional to the third power of the gap height or the height h of the pocket gap through which the medium flows. The result in the case of laminar flow is the condition Q~p·h
3
/&eegr;, &eegr; denoting the dynamic viscosity of the medium or the liquid. This relationship is valid in a similar way for gaseous media.
It follows from the assignment reproduced here that the change in the height h owing to a pressure change in the hydrostatic pocket through an increase in the liquid flow or the flow rate Q can be reduced, or virtually completely avoided. Thus, if a hydrostatic pocket is loaded such that the pressure prevailing in this hydrostatic pocket is increased, it is possible to counteract a change in gap height, and thus a displacement of the parts which are guided or supported, by virtue of the fact that the fluid flow flowing from the controller into the hydrostatic pocket is enlarged. The result of this is a higher stiffness.
The known controller is conceived such that normally at least two controllers are combined in one block and are fed by a common pressure connection. This concept leads in many cases to the fact that it is necessary to create relatively long connecting lines between the controllers and the hydrostatic pockets with an outlay which is partly considerable, the spatial accommodation of these lines frequently being very difficult, for example, when supplying screw drives which have a hydrostatic nut. It is, furthermore, disadvantageous in the known controller that the latter frequently tends to vibrate because of the high kinetic energy of the fluid/gas in the lines.
It is therefore the object of the invention to create a controller which can be used for liquid and also for gaseous media and which does not have the said disadvantages.
In order to achieve this object, a controller is proposed which has the features named in claim
1
. The controller is distinguished in that the mating surface is assigned to the bearing, the threaded spindle nut or the guide, and wherein the controller housing has a bearing surface, comprising a passage orifice for the medium flow, with the aid of which in the mounted state the controller housing bears against the mating surface assigned to the bearing, the threaded spindle nut or the guide, thus creating a direct medium connection between the controller and pocket and, if appropriate, between the controller and the medium supply. In connection with the present invention, a “direct” medium connection is understood to be a connection which is made without screwing and additional mounting elements. Thus, the medium connection is formed at the same time as the controller is fitted on the mating surface. As a result, it is possible to simplify the design of the controller, on the one hand, and to reduce the outlay on mounting it, on the other hand. The mating surface can, for example, be a partial surface of a housing of the bearing, the threaded spindle nut or the guide. It is thereby possible to arrange the controller in the immediate vicinity of the hydrostatic/aerostatic pocket, so that it is possible to implement short connecting lines between the controller and the pocket. It is thereby possible to prevent vibrations of the medium in the connecting lines, but at least largely to reduce or weaken them. The controller can be mounted simply and quickly and is also distinguished by a simple design.
In an advantageous embodiment of the controller, it is provided that the controller housing comprises at least two housing parts between which the first pressure chamber, the control element, the second pressure chamber and the second flow resistance are arranged. It is thereby possible to implement a particularly compact design of the controller.
Also preferred is an embodiment of the controller in which the first flow resistance is recessed into the bearing surface, formed on the first housing part, and/or into the mating surface. “Recessing” is understood to mean both the introduction of the first flow resistance by means of a cutting tool, for example a miller, and noncutting machining. The first flow resistance can thus also be pressed or forced into the surface provided therefor, or can be molded during production of the first housing part and/or the mating surface.
Further advantageous refinements follow from the remaining subclaims.
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Hepperle Stephen M.
Ostrolenk Faber Gerb & Soffen
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