Fluid handling – Self-proportioning or correlating systems – Self-controlled branched flow systems
Reexamination Certificate
1997-05-16
2001-06-19
Rivell, John (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-controlled branched flow systems
C137S544000, C123S510000, C210S446000
Reexamination Certificate
active
06247486
ABSTRACT:
PRIOR ART
The invention relates on a liquid filter with a built-in pressure regulator for fuels in accordance with the species disclosed in more detail in the preamble of claim
1
.
Such a liquid filter with a built-in pressure regulator for fuels is already known from U.S. Pat. No. 5,078,167, wherein the otherwise separate components, such as the filter and the pressure regulator, are combined in a common unit and are known by the name returnless fuel systems (RLFS). The pressure regulator of such a liquid filter operates with a diaphragm, on which the pressure to be regulated acts against the force of a spring. It is disadvantageous in connection with the liquid filter that the flow through the filter element here goes from the inside to the outside, which can result in a considerable reduction of its service life; bridges can be formed because of deposits, which reduce the entry cross section, which is critical in particular when large amounts of dirt are developed. Furthermore, it is necessary here to return the pressure from a clean side of the filter element to a side of the diaphragm, for which purpose an elaborate chamber structure on the diaphragm is required. It is furthermore disadvantageous here that the pressure regulator is placed between the inlet connector and the tank connector and therefore is completely situated on the dirt side of the filter element. Because of this dirt particles can get into the valve of the pressure regulator and hamper its function. The actual valve of this pressure regulator represents a component separated from the diaphragm, which results in a relatively elaborate construction, which also requires many shaped sheet metal elements. The ring-shaped diaphragm must be clamped on its inner and its outer edge, because of which the risk of drift is increased. Furthermore, this filter is designed for installation in a tank and has an unguided fuel return, so that it is not well suited for connection by means of lines. Mainly, however, the function of the pressure generator is interferingly affected by possible backpressure, which occurs in particular when using jet pumps in the tank.
A liquid filter with a built-in pressure regulator is furthermore known from U.S. Pat. No. 4,011,848, wherein the liquid filter is essentially designed as a line filter, on whose oppositely located front ends of the housing the inlet connector and outlet connectors are disposed. A third connector with the tank, in which a simple ball valve is provided as the pressure regulating valve, extends radially from the side of the housing. A safety valve is furthermore assigned to the outlet connector, which is intended to block the connection to the tank when the fuel supply fails. The pressure regulator of this liquid filter is also directly connected with the dirt side. The pressure regulator here operates without a diaphragm and, because of the ball valve used, is relatively inaccurate and prone to become dirty. The perpendicular position in respect to each other of the connectors for the outlet connector and the tank connector is very unfavorable in many installation cases.
A liquid filter is furthermore known from DE 44 30 852 A, into whose housing cover a pressure regulator has been integrated in such a way that the flow through the filter element runs from the outside to the inside and the pressure regulator lies on the clean side. The embodiment of the pressure regulator in the cover cannot be seen there; the cover with the pressure regulator requires much space.
ADVANTAGES OF THE INVENTION
In contrast thereto, the liquid filter in accordance with the invention with a built-in pressure regulator for fuels, having the characterizing features of the main claim, has the advantage that an extremely simple, compact and cost-effective construction is made possible with this integration of the pressure regulator into the liquid filter, wherein the operation of the pressure regulator is independent of any backpressure at all; therefore it can be easily used in connection with jet pumps in the tank, since their backpressure no longer has an effect on the pressure control. Since pressure medium acts on the pressure regulator only from the clean side, only clean fuel flows through all its components, so that wear or leaks caused by jammed dirt particles is impossible. With this type of construction it is furthermore possible the the flow through the filter element takes place in the most advantageous manner from the outside to the inside, so that by means of this the same service life as with a filter alone can be achieved. The liquid filter with the integrated pressure regulator can be easily and simply installed at any arbitrary location of the vehicle; no additional connections at the tank are necessary. The integrated construction of the pressure regulator allows a particularly assembly-friendly structure which, because of its cost-efficient construction, is also suitable for throw-away filters. The amount of liquid flowing off when the pressure regulator is actuated can flow off relatively unhampered, which favors a compact and small structural size. Also, the danger of flow noises and pressure pulses is considerably reduced, since the liquid flow is guided without any extensive deviations and has an essentially constant course from the inlet to the outlet. The pressure regulator compensates a possible pressure drop, which can be caused by the addition of a filter in an advantageous manner in that the regulation is performed on the clean side.
Advantageous further developments and improvements of the liquid filter with a built-in pressure regulator disclosed in the main claim are possible by means of the steps recited in the dependent claims. Thus, by means of claim
2
, an increased service life can be achieved because of the advantageous flow through the filter element. Embodiments in accordance with claims
3
and
4
favor a simple and compact construction, which in addition can be made more cost-effective and is advantageous in assembly and handling. Furthermore, the embodiments in accordance with claims
5
to
8
are also advantageous, wherein the arrangement of the inlet connector and the tank connector on the same front face of the housing results in short hose connections between the filter and the tank. The disposition of the pressure regulator in the housing also results in that the clamping position of the diaphragm, which is critical in connection with sealing, is located inside the housing, so that no additional sealing place toward the exterior is created. It is also possible to save a component by integrating the pressure regulator in the housing. It is advantageous for a safe and extended operation of the pressure regulator if in accordance with claims
9
or
12
a sealed connection is provided. It is furthermore advantageous if in accordance with claim
10
the pressure regulator is embodied as a plug-in module, because of which it can be constructed particularly cost-effectively and simply; in addition, the danger of an excursion of the diaphragm is reduced by the pressure connection at the clamping position. A particularly advantageous and compact construction results in accordance with claims
12
to
16
, which in addition permits a simple assembly. In this connection it is advantageous if in accordance with claim
17
plastic components are used. Further advantageous embodiments ensue from the remaining claims, the specification and the drawings.
REFERENCES:
patent: 3695438 (1972-10-01), Malpassi
patent: 4011848 (1977-03-01), Coddington
patent: 4971689 (1990-11-01), Burrows
patent: 5078167 (1992-01-01), Brandt et al.
patent: 5275203 (1994-01-01), Robinson
patent: 5433241 (1995-07-01), Robinson
patent: 92 14 297 (1994-12-01), None
patent: 4430852A1 (1995-04-01), None
patent: 443 04 71 (1996-02-01), None
patent: 0 702 142 A1 (1996-03-01), None
Bueser Wolfgang
Lucas Bernhard
Projahn Ulrich
Schwegler Helmut
Rivell John
Robert & Bosch GmbH
Striker Michael J.
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