Liquid purification or separation – Flow – fluid pressure or material level – responsive – Fluid pressure responsive by-pass
Reexamination Certificate
2001-12-18
2003-09-02
Drodge, Joseph (Department: 1723)
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Fluid pressure responsive by-pass
C210S167150, C210S171000, C210S432000, C210S497300
Reexamination Certificate
active
06613221
ABSTRACT:
BACKGROUND
The invention is directed to a sieve filter for fluid conduits having a hollow cylindrical main body with a fluid inlet and a fluid outlet, and a fine mesh filter element adapted to allow fluid flow therethrough, with a bypass for use when the filter element is stopped up or in the event of highly viscous fluid, and it is especially advantageously suited for hydraulic pressure lines in internal combustion engines.
It is generally known to the person skilled in the art that, after assembly of the individual parts of an internal combustion engine, it is not possible to avoid some finishing-related dirt particles, such as shavings, jointing solution residues and the like, remaining in the interior of internal combustion engine despite cleaning of the individual parts. Especially with internal combustion engines which are outfitted with a hydraulic device for relative rotation of the camshaft relative to the crankshaft of the internal combustion engine, there exists the danger of these dirt particles getting into the lubricant circulation of the internal combustion engine from which also the device for relative rotation of the camshaft is hydraulically supplied. Since as a rule an electromagnetic control valve is connected in series ahead of this device, which controls fluid feed and removal to and from this device through one of the camshaft bearings in the cylinder head of the internal combustion engine, it is consequently not to be ruled out that if dirt particles exceed a certain magnitude, they will cause impairments in the function of the control valve up to completely blocking it. A thorough cleaning of the individual parts of the internal combustion motor for avoiding these impairments of function has, however, above all in mass production, proven to be uneconomical, so that in order to create a remedy, first of all a fine mesh wire filter was incorporated into the oil duct to the electromagnetic control valve of the device. This filter indeed protects the control valve from the penetration of dirt particles, but in practice it has nonetheless become apparent that if the filter becomes completely stopped up, not only do malfunctions occur with the device to be controlled, but also undersupplying lubricants to the camshaft bearing used to feed and remove fluid occurs, which can in the worst case lead to total failure of the internal combustion engine due to bearing seizures.
Through genus-defining EP 0 965 376 A1, a rod-like pipe filter for fluid conduits was proposed which is arranged in a junction of a pressure line and makes available a bypass function when the filter element is stopped up. This pipe filter basically consists of a fine mesh filter element and a hollow cylindrical main body of plastic which forms a fluid inlet and a fluid outlet through stiffening bars joined with each other. The stiffening bars are here provided with cam-like spacers which keep the filter element at a distance to the walling of the pressure line. The fluid inlet of the pipe filter is sealed off toward the walling of the pressure line while the fluid outlet lying on a shoulder in the pressure line has several bypass openings which create a connection from the interior of the pipe filter to the exterior. Under normal operating conditions, the main flow of the fluid consequently takes place through the interior of the pipe filter through its filter element into the exterior as well as toward the junction of the pressure line. When the filter element is stopped up, or in the event of highly viscous fluid, the fluid reaches the exterior unfiltered through the bypass openings in the fluid outlet to the exterior and consequently likewise the junction of the pressure line.
The disadvantage with this known pipe filter is, however, that this is usable only in the region of a junction of a pressure line and consequently presupposes a certain configuration of the fluid passages in an internal combustion motor which do not always exist or are not always realizable. Above and beyond this, the construction of the bypass function of this pipe filter has, at least under normal conditions, the disadvantage that the fluid, following the principle of the least resistance, rather passes unfiltered through the constantly opened bypass opening in the fluid outlet to the exterior of the pipe filter as well to the junction of the pressure line than flows filtered as anticipated through the fine mesh filter tissue to the exterior of the pipe filter and to the junction of the pressure conduit. In this way, a pipe filter of this type is practically functionless, so that the dirt particles contained in the fluid most of the time forge ahead unhindered to the unit to be provided with a finely filtered fluid and can cause the functional disturbances mentioned with an electromagnetic control valve. Moreover, it cannot be ruled out that when using the fluid flow through the bypass openings at the fluid outlet of the pipe filter, already filtered out dirt particles from the interior of the pipe filter are carried along through the bypass openings to the junction of the pressure line so that the danger of functional disturbances on an electromagnetic control valve is increased even further.
Moreover, through DE 37 18 068 C1, an additional rod-like sieve filter is known which is comparable in basic construction with the previously mentioned solution and is especially suited for incorporation in the flow pathway of a hydraulic control device of a fuel injection pump for an internal combustion engine. This rod-like sieve filter likewise constructed with a bypass function has (for the event of a paraffin stoppage of its sieve mesh fabric at extremely low temperatures) in its interior an additional bypass pipe with a pressure relief valve opening in the direction of flow which is arranged at the height of the fluid inlet of the sieve filter and is constructed as a sprung ball valve or as a thermostat valve.
With this inherently very advantageous sieve filter for fluid lines, it is indeed possible to avoid the disadvantages of the previously mentioned solution to a great extent. But it has the disadvantage that its manufacture demands high finishing expenditures and costs due to the additional bypass pipe.
SUMMARY
For this reason, underlying the invention is the object of designing an economical sieve filter for fluid lines which is simply assembled with regard to construction, especially for hydraulic pressure lines in internal combustion engines, which is insertable at any desired site within a fluid line or passage and makes available a bypass function which permits a fluid flow through the bypass only when the filter element is clogged or in the event of highly viscous fluid and thereby avoids carrying along dirt particles already filtered out of the fluid.
In accordance with the invention, this object is accomplished with a sieve filter having a hollow cylindrical main body (
3
,
3
′) with a fluid inlet (
4
,
4
′) and a fluid outlet (
5
,
5
′), and a fine mesh filter element (
6
,
6
′) adapted to allow fluid flow therethrough, with a bypass for use when the filter element (
6
,
6
′) is stopped up or in the event of highly viscous fluid, wherein the fluid outlet of the sieve filter stands in operative connection with a spring element, and the sieve filter together with the spring element is insertable between two opposing surfaces spaced axially apart inside the pressure line so the fluid inlet of the sieve filter and the spring element lie under prestress on the opposing surfaces, and the main body of the sieve filter is movable axially between the opposing surfaces. The main body of the sieve filter thereby closes off, when the filter element is subject to normal through flow, an additional bypass fluid channel passing the filter element of the sieve filter which is openable when the filter element is clogged or in the case of highly viscous fluid, through an axial displacement of the main body of the sieve filter against the force of the spring element resulting from the ris
Golovatai-Schmidt Eduard
Lauterbach Frank
Ottersbach Rainer
Cecil Terry K.
Drodge Joseph
INA-Schaeffler KG
Volpe and Koenig P.C.
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