Fluid handling – Systems – Multi-way valve unit
Reexamination Certificate
1999-03-19
2001-10-23
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Systems
Multi-way valve unit
C029S890131, C137S315090, C137S625690, C251S367000
Reexamination Certificate
active
06305418
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a hydraulic valve, in which by relative movement between a piston and a housing, which in spatially defined configuration has supply and user connections, via which pressure medium can flow from a pressure supply aggregate to a user and from this back to a supply container of the pressure supply aggregate, various defined flow paths can be selected, which are associated with various defined functions of the user, for example, forward movement, resting or backwards movement of the piston of a hydraulic cylinder, wherein in various functional positions of the hydraulic valve various respectively defined combinations of flow paths are opened or closed off or subcombinations of such paths are opened and other sub-combinations closed off, wherein segments of such flow paths are formed by grooves in the housing and/or the piston as well as housing and/or piston channels, which communicatingly connect such path sections with each other or with supply or as the case may be user connections.
DESCRIPTION OF THE RELATED ART
n-way/m-position-valves of this type are generally known and are offered as either switch valves which are switchable between discrete functional positions or as proportional valves which, with increasing displacement of their piston out of a base position, increasing open up a flow-path cross-section, and are offered by hydraulic component suppliers in the most compatible, that is, corresponding, variations of known configurations of their supply, user and/or control connections, so that a unit manufactured by one manufacturer is exchangeable with a corresponding unit of another manufacturer.
The housing of such valves is as a rule produced of aluminum or steel cast parts, in which at least the basic shape as defined by a central through-going housing channel, which receives the valve piston, the basic shape of this channel including widening grooves, the flow in such grooves joining lengthwise or transverse channels, which are in communicating connection with connection openings of the valve housing, as well as the flow or path of channels which internally connect housing grooves with each other without being directly in communicating connection with a supply or user connection of the valve housing, is predetermined by the shape of a cast core, which is introduced into the outer cast shape, which in turn determines the shape of the outer surfaces of the housing, wherein this cast core after the casting of the valve housing can fall apart and the core material, fine grained sand, must be quantitatively removed in a simple manner from the cast body.
This embodiment of the valve housing as cast part is completely practical in the view point of a highest possible fluid-tightness (avoidance of the requirement for an external plugging internally with each other communicating transverse and longitudinal boreholes of the housing), the mechanical load carrying capacity and also the somewhat rational manufacturing process; however it is also associated with a variety of serious disadvantages:
Even when it is so organized, that a rational manufacturing process of numerous housings is possible in a single casting process, the production of the cast core is associated with a high technical demands, which is expensive.
The shapes of the housing hollow spaces in the housing, which during casting are filled with sand kernels, must be so constructed or shaped, that the kernel material after the casting is reliably removable after casting. Herein it is required, for reasons of the sufficient stability of the casting kernels, that minimum cross-sections of cast core batches are required, which for example connect housing internal grooves of the central housing channel with each other.
Since a follow-up processing of the central channel of the cast housing, for example with conventional penetrating tools, is unavoidable in order to achieve sufficiently precise housing side control edges, through which by positive or negative overlapping with piston side control edges the various functional positions of the valve are achievable, the axial separation of such housing side control edges must as a rule be selected to be substantially greater than would be necessary from flow technical reasons. The manufacturing length of the known valves is thus for reasons of product finishing as a rule significantly greater than would be required for physical reasons. Correspondingly, the axial dimensions of the pistons in linear displacement valves must be greater, which also results in a corresponding enlargement of their mass.
SUMMARY OF THE INVENTION
The task of the invention is thus, to improve a hydraulic valve of the above-described type such that it can be manufactured, without detracting from the functional characteristics and the precision of the arrangement and construction of its control edges as well as with a good sealing of the housing, with substantially less expenditure and also can be produced with significantly smaller spatial dimensions.
According thereto the housing of the valve is assembled from planar-parallel, plate-shaped segment-sheets, in which segments of longitudinal channels of the housing are formed by clearances having a cross-section with a closed edge, which overlap or are aligned with corresponding channel sections of adjacent channels; radial channels or segments of such channels, which are connected in communication with a supply connection or a user connection, are formed by radial bulges of central openings of the housing segments, which are oriented or provided along a common central longitudinal axis; the cross-section of a housing channel defined by the edges of a central opening, within which the valve piston in pressure type manner is axially displaceable and/or rotationally turnable, radial widening grooves are formed by clearances of larger diameter of the housing segment which positively overlap the central channel in cross-section; the segment plates are materially joined by brazing, wherein during the brazing process they are positively and form-fittingly joined or in certain cases materially joined into a dimensionally stable package; a brazing material required for the mechanically secure material joining of the segment plates is introduced into enclosed compartments, which are formed by group-wise interconnecting clearances of the segment plates and which extend over the entire series of the segment plates.
By this design of the inventive valve technical advantages are achieved including at least the following: The clearances or through-holes of the individual segment sheets can be produced on NC- or CNC-controlled bore and/or punching or stamping machines with high precision, wherein also channel paths can be produced in simple manner, which in casting technology practically are not realizable or are realizable only at great expense.
Since axial groove widths are determined in simple manner by the thickness of the segment sheets, which by the edge of their clearances determines the flow path of the groove base, such groove widths can in simple manner be limited to the physically required minimal value and for example in the case of magnet controlled linear displacement valves, can be tailored to the lift or stroke of the available control magnets, whereby shortenings of the axial construction length of the valve housing can be achieved which correspond to 30% of the construction length of a conventional valve housing. The mass of the piston is also reduced by a corresponding percentage value.
The thin brazed layers, which are produced as a result of the capillary action between the sheet metal plate segments, produce an absolute tight and secured connection of the housing segments with each other. The sealing and mechanical load capacity of the housing is equivalent to that of a conventional cast housing. It can further be said that the casting flaws which are statistically unavoidable with cast housings, for example contraction cavities, cannot occur, so t hat the valve housings produced according to
Michalsky Gerald A.
Pendorf & Cutliff
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