Patent Application
20240216838
This application claims priority to German Patent Application No. DE 10 2021 002 647.0, filed on May 20, 2021 with the German Patent and Trademark Office. The contents of the aforesaid Patent Application are incorporated herein for all purposes.
The invention relates to a filter device comprising a filter housing which has an inlet for unfiltered medium and an outlet for filtrate and which accommodates a replaceable, hollow cylindrical filter element for a flow of unfiltered medium from outside to inside.
This background section is provided for the purpose of generally describing the context of the disclosure. Work of the presently named inventor(s), to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
A filter element designed as a replaceable element is disclosed in WO 2018/082799 A1, the element material of which, formed as a hollow body and extending between two end caps, is pleated with individual filter pleats, the element material comprising a filter material made of cellulose. When the fluid flows through, the cellulose fibers have a coalescing effect, resulting in the formation of enlarged droplets from the water portion of the emulsion which sink to the bottom due to the difference in density of water and oil, so that separation of the less dense medium takes place. A filter element of this type separates the aforementioned water in a reliable manner and is additionally cost-efficient to produce.
The known filter element can be fixed in a device with a filter housing by means of a mounting rod as part of a fixing device, each end cap of the filter element having a spacer with a sealing function, one on the fixing device and one on an intermediate base of the filter housing. In this manner, there is no need for any additional holding means that protrude beyond the outer circumference of the filter element, which enables a space-saving design.
EP 3 334 512 B1 discloses an oil filtration unit for removing solid contaminants from contaminated oil, comprising:
The associated oil filter or filter element is formed as a hollow cylinder and consists in this respect of cellulose material. A disc-shaped end plate of the oil filter comprises the filter outlet of the filter housing, it being possible for the corresponding end plate to comprise a porous material of natural or synthetic polymer and cellulose material. The flow passes through the known filter element, as the oil filter, from the inside out, a hydraulic resistor being formed by the said end plate made of porous material, which resistor in this respect provides a flow restriction between the inner filter volume and the environment in order to achieve the pressure graduation p1>p2>p3 already mentioned. The purpose of this pressure graduation is to prevent a back pressure for the filter element in this way which occurs, for example, if a hydraulic pump device or similar is connected on the output side of the filter.
In addition to the flow from outside to inside, it is necessary for operation that the element material on the base end of the filter element is provided with a sealing device with respect to the accommodating filter housing which, on the one hand, limits the effective filter surface on the filter element and, on the other hand, entails a certain amount of technical equipment effort on the filter housing.
A need exists to provide a filter element that enables a functionally reliable filtration operation, wherein the efficiency during filtration is improved.
The need is addressed by filter devices and methods for operating a filter element according to the independent claims. Embodiments of the invention are described in the dependent claims, the following description, and the drawings.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description, drawings, and from the claims.
In the following description of embodiments of the invention, specific details are described in order to provide a thorough understanding of the invention. However, it will be apparent to one of ordinary skill in the art that the invention may be practiced without these specific details. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the instant description.
In a filter device according to some embodiments, it is provided that when unfiltered medium flows through the replaceable filter element from outside to inside, it flows through both a hollow cylindrical element material and an element material which closes off said hollow cylinder at its one free end, at the other free end thereof, an element cap with a central recess is used to discharge filtrate to the outlet in the filter housing which outlet is connected to the central recess, and the respective element material is accommodated seal-free in the filter housing for flow around all sides, from outside to inside, with the result that there is only one single pressure stage, at which the pressure p1 outside the filter element is greater than the discharge pressure p2 on the inside of the hollow cylindrical element material that is closed off towards one side. This results in a substantially improved cleaning balance for the flow of unfiltered medium and proves to be favorable in terms of energy which is also helped by the fact that the hollow cylindrical element material is accommodated on its filtrate discharge side with a continuous discharge opening within the filter housing so that the flow through the filter element takes place to this effect from the base to the head end. The corresponding upward filtration direction for the flow of filtrate to the pressure-reduced discharge side is also favorable from the energy balance point of view.
Since the flow through the element material of the filter element as a whole is from outside to inside and accordingly no additional sealing device of the filter housing engages on the element material on the base end, the full filter surface is available for filtration and the technical equipment effort is reduced due to the omission of such a sealing device.
The filter element for the filter device for example consists entirely of cellulose material on the circumference of the hollow cylindrical element material and also for element material closing off the hollow cylinder which is particularly beneficial, due to the homogeneous formation of the element material, when it is necessary to separate small-particle contaminants from a fluid flow which is the case, for example, when there is a desire to separate oil ageing products (varnish) from the a fluid flow. The method ensures a filtration operation to this effect with the above-mentioned device together with filter element and, due to the only single pressure stage p1 present, fluid resistances in the direction of p2 are reduced and a high filtration performance is achieved during use of the method.
In some embodiments of the filter element, it is provided that the hollow cylinder of the filter element is formed of individual, for example identical, annular filter discs which, arranged one above the other, are firmly connected to one another, for example bonded to one another, on their mutually adjacent end faces and in that the element material which closes off the hollow cylinder at its one free end is formed of a closed filter disc. In this way, the filter element can be constructed in any length, the flow passing through the same annular filter disks which are arranged one above the other, in the sense of a modular system. In addition, the annular filter disks can be produced in large numbers as identical components in the manner of series production which is cost-efficient.
In some embodiments of the filter element, it is provided that all filter discs of cellulose material have the same filter properties, in particular the same filter fineness, and in that the annular filter discs are all constructed identically in terms of their element material. The said filter disks made of cellulose are produced in accordance with DIN EN ISO 5269-2 using the so-called Rapid-Kathen method and, as a standardized method in this respect, a high level of process reliability is achieved during production.
In some embodiments of the filter element, it is provided that the individual annular filter disks have recesses on the outer circumference which are formed by incisions or by adjacent spacers between the filter discs. On the one hand, the recesses obtained increase the stability in the composite sheet with the individual filter discs and permit flow guidance for the flow of unfiltered medium which flows through the filter element with the filter discs from outside to inside. Beneficially, in this case the disc-shaped element material which closes off the hollow cylinder at the end can be provided with an additional geometry, for example in the form of an inlet device which engages in the interior of the hollow cylinder. For targeted flow guidance inside the hollow cylindrical filter element from the base end towards the head end of the filter element, the inlet device may for example, in terms of the outer circumference, have a trumpet shape, the largest cross-section of which merges integrally into the element material of the closed filter disc. Since the inlet device on the base end of the element material also represents a certain resistance for the flow through the filter element, there is an improved flow in the head region of the element and thus overall a homogenised flow distribution during filtration operation.
In some embodiments of the filter element, it is provided that the hollow cylindrical element material is held between two end caps, the one end cap of which, configured as a twin mounting, simultaneously serves to fix the closed, disc-shaped element material to the end of the annular element material. In this way, the hollow cylindrical element material can be separated from the disc-shaped element material by means of the twin mounting and each can be replaced separately with a new element material. For example, however, it is provided that the disc-shaped element material is permanently bonded or welded to the hollow cylindrical element material at the end so that the disc merges into the hollow cylinder without a gap. In this way, a homogenized incident flow is also achieved in the region where the disc-shaped element material joins the hollow cylindrical element material and the filter element constructed in this way can be replaced as a whole with a single new element.
For improved flow guidance and in some embodiments, it is further provided that the two end caps each have a central recess, the diameter of which is identical, the diameter of the end cap with which the filter element can be connected to an outlet of the filter housing having a diameter which corresponds to the inner diameter of the hollow cylinder of the filter element. In particular, the latter feature enables resistance-free discharge of the filtrate towards the outlet of the filter device.
For example, the closed, disc-shaped element material is to be formed from a filter blank which comes from a sheet former, in particular from a Rapid-Kathen sheet forming system available on the market.
In an example method for operating a filter element in a filter device as discussed above, the system is used to clean contaminants, for example varnish, from a fluid flow, the filter element being accommodated in a filter housing, with an inlet for unfiltered medium and with an outlet for filtrate, wherein, when unfiltered medium flows through the filter element from outside to inside, it flows through both a hollow cylindrical element material and an element material which closes said hollow cylinder at its one free end, the filtrate flow being guided from the inside of the hollow cylinder to the outlet of the filter housing, and the respective element material being accommodated seal-free in the associated filter housing for flow around all sides, from outside to inside. Varnish is regularly not listed in the literature as a “hard” particle and thus does not represent actual particulate contamination; in fact, it is routinely sludge-like oil ageing products.
The cellulose used for the filter element can be constructed in the manner of a composite material. In this case, the cellulose can be combined with fillers, additives, filter aids, etc.
Silicates, for example kaolin, carbonates, for example chalk; sulphates, for example gypsum, barium sulphate; oxides, for example titanium dioxide; aramid fibers and/or carbon fibers, are regularly used as fillers. Suitable additives include sizing agents, binder systems, dry and wet strengtheners, pigments, dyes, dewatering and retention agents, and defoamers. Diatomaceous earth, silica gel, perlite, zeolites or activated carbon can be used as filter aids.
Reference will now be made to the drawings in which the various elements of embodiments will be given numerical designations and in which further embodiments will be discussed.
Specific references to components, process steps, and other elements are not intended to be limiting. Further, it is understood that like parts bear the same or similar reference numerals when referring to alternate FIGS.
To replace the filter element 16, a head-end housing part must be separated from a foot- or pot-end housing part holding the filter element 16, which is common practice, with the result that this will not be discussed in greater detail here. The upper element cap 26 is slid on over a connection socket as part of the outlet 14 and is sealed in this region via a sealing ring 30 on the housing side as the only seal between the element 16 and the housing 10. Otherwise, the respective element material 18, 22 is accommodated seal-free in the filter housing 10 according to
In the embodiment of a filter element 16 shown in
As the embodiment according to
As
In the embodiment according to
In the embodiment according to
As
The solution according to the teachings herein is used in particular to remove so-called varnish from a fluid flow, regularly formed of oil ageing products which are not listed in the literature as “hard particles” and which accordingly do not represent particulate contamination in the proper sense. The application further relates to dewatering, in particular cellulose has the property of being able to absorb water. In this way, it is also possible to achieve oil-water separation. Finally, there is also the possibility of particulate filtration.
The invention has been described in the preceding using various exemplary embodiments. Other variations to the disclosed embodiments may be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor, module or other unit or device may fulfil the functions of several items recited in the claims.
The term “exemplary” used throughout the specification means “serving as an example, instance, or exemplification” and does not mean “preferred” or “having advantages” over other embodiments. The term “in particular” and “particularly” used throughout the specification means “for example” or “for instance”.
The mere fact that certain measures are recited in mutually different dependent claims or embodiments does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 002 647.0 | May 2021 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/061180 | 4/27/2022 | WO |
