The filter device as claimed in the invention will be detailed below using one embodiment. The figures are schematic and not to scale.
FIG. 1 shows a front view of a longitudinal section of the head-side part of the filter device as claimed in the invention;
FIG. 2 shows the filter element which can be inserted into the filter device as shown in FIG. 1 with a trigger part in a perspective top view;
FIG. 3 shows a perspective top view of the trigger part as shown in FIGS. 1 and 2;
FIGS. 4 to 7 show in a perspective top view different embodiments of insertable valve means, FIG. 6 showing the opened operating state of the valve means as shown in FIG. 5.
The filter device as shown in FIG. 1 has a cup-shaped filter housing part 10 which surrounds the filter element 12, as is shown for example in FIG. 2. Flow takes place through the filter element 12 from the outside to the inside viewed in the direction of looking at FIG. 1 and the filter element has a conventional filter element structure which is not detailed, for example consisting of a pleated, multilayer filter mat which is supported against a fluid-permeable support pipe. In this connection, fouled fluid is optionally supplied from a hydraulic circuit which is not detailed via the fluid supply 14 to the filter device, and cleaned, filtered fluid travels via a center channel 16 of the filter element 12 to the fluid discharge 18 of the filter device. In order to be able to backflush the filter element 12, it would also be conceivable to operate the filter device in the reverse fluid direction; likewise it would be possible in a specially designed filter element 12 to reverse the direction of fluid throughflow so that then the fluid to be cleaned flows through the filter element 12 from the inside to the outside. In these instances then, generally to support the pleated filter material, a support pipe or other support element such as a grating must be attached on the outer peripheral side. This structure of a filter device is conventional so that it will not be detailed here. It is likewise conventional for the other filter housing part 20 which forms a type of filter head to have a supply 14 and a discharge 18 and to extend over the filter housing part 10 on its upper free end on the front and to be detachably connected to the filter housing part 10 via a screw-on section 22.
The filter device furthermore has a valve means 24 as shown in FIG. 4. Other solutions for the valve means 24 are shown in FIGS. 5 to 7. If, as shown in FIG. 1, the two housing parts 10, 20 are connected to one another, the valve means 24 is moved into the open position which clears the fluid-carrying path, and in the separated state of the housing parts 10, 20 from one another the pertinent fluid-carrying path between the center channel 16 and the fluid discharge 18 is blocked. In the absence of a control part and designed as a complete closure (valve function) the valve means remains closed until the pressure p1 has reached or exceeded the opening pressure P0 of the valve means, i.e., p1<p0:p2=0 for an unpressurized connection to the tank, volumetric flow Q=0, p1>=p0:p2=p1·Δpvalve, ideally for Δpvalve=0:p2=p1.
In the absence of the control part and designed as a choke (spiral disk with passages) a pressure drop will take place over the component so that p1>p2. The resulting pressure difference Δpvalve is used to trigger a signal of an optionally connected fouling display.
As shown in greater detail in FIG. 4, the valve means 24 has a valve element 26 which can be actuated via a trigger part 28, as is detailed in FIG. 3. In this case the trigger part as shown in FIGS. 1 and 2 is a component of the filter element 12, and as a result of its conically tapering control parts on its free front end in the form of opposing bridge surfaces is able to push against the closed valve disk as shown in FIG. 4, into an open spiral configuration, as shown in FIG. 1. If the two filter housing parts 10, 20 are separated from one another by unscrewing over the screw-on section 22, the trigger part 28 disengages from the valve means 24, and the valve element 26 assumes its largely closed position in the form of a flat membrane surface as shown in FIG. 4.
Since the valve component of the valve element 26 in the embodiments as shown in FIGS. 1 and 4 is consequently formed from a spiral arm 32 with spring-elastic properties, this process of pushing can be repeated as often as desired for an opening process and spring-elastic resetting for closing the valve means 24 so that in this way a very large number of changing processes for new filter elements 12 is possible if, when fouled, they are to be replaced accordingly by new filter elements. Since the valve means 24 can be fixed interchangeably in the upper filter housing part 20, for a possible failure of the spiral arm 32, replacement of the valve element 26 is also possible. This interchangeability is however not absolutely necessary. The spiral arm 32 which can be obtained from a flat metal plate can be obtained by means of conventional cutting technology, also including laser cutting, water jet cutting, etc. A correspondingly wound wire with round or rectangular cross section could likewise be used.
The metal base plate as the base material, preferably made in circle form, itself need not be spring-elastic, and the resetting moment for closing the valve means 24 can likewise arise exclusively by the raising of the spiral arm 32 in helical form by the trigger part. The raising plug 34 which tapers to the outside (compare enlargement as shown in FIG. 3) in terms of its outside contour is matched to the spiral line of the raising arm so that in this way the spiral arm 32 undergoes guidance both for the pushing process and also for the resetting process which in this respect ensure especially careful actuation of the valve element 26. Fundamentally however a cylindrical raising pin (not shown) could assume the function of the conical raising plug 34.
The trigger part 28 is shown as an individual component in FIG. 3 for better illustration. The trigger part 28 on the bottom side has a contact-making plate 36 which can be moved into the top end of the filter element 12 until the free end of the filter element 12 comes into contact with the encompassing edge 38. This encompassing edge 38 on the outer peripheral side has an engagement groove 40 which is interrupted by engagement points 42 which point down, which are preferably diametrically opposite one another, and which ensure that by way of a corresponding catch or lock connection the annular trigger part 28 is detachably fixed with a corresponding strip-like or cam-like engagement part 44 on the inside of the cup-shaped filter housing part 10 (compare FIG. 1). A cylindrical center plug 48 is located on the top of the contact-making plate 36 by way of individual stiffening bridges 46 and is permanently connected to the contact-making plate 36 and to the encompassing edge 38, the individual stiffening bridges 46 extending radially to the outside away from the longitudinal axis 50.
The top of the center plug 48 is connected to the aforementioned raising plug 34, the three inserted control parts 30 extending between an annular flange 52, on the top end of the center plug 48, and a contact-making and pushing pin 54 on the free end of the trigger part 28. These bridge-like trigger parts 30 can be further stiffened by at least one middle ring 56. The fluid passages 58, bordered by the stiffening bridges 46, and the top of the contact-making plate 36 and the bottom of the encompassing edge 38 are used for incident flow onto the actual filter element with its filter medium in the seated state. The fluid passages 58 more or less form the inflow channel between the filter element and the optional “dirt catcher” which is shown here and which is used to catch dirt in the direction of flow through from the outside to the inside. The insertion bevels 60 which point down on the stiffening bridges 46 facilitate insertion of the trigger part 28 into the (optional) dirt catcher along its upper edge. This trigger part 28 consists preferably of a plastic material which can be economically produced for example by means of an injection molding process. For permanent connection of the trigger part 28 which is made in one piece to the filter material of the filter element 12 there can be a cement connection which is not detailed. Instead of three control parts 30, there can also be a different number of control parts (not shown).
The filter element 12 with the trigger part 28 forms a type of manageable function unit which can be completely replaced as a replacement part and thrown away. But it is possible to reuse or recycle the plastic trigger part 28. It is still within the scope of the invention, in an embodiment which is not shown, to assign the trigger part 28 to the other filter housing part 20 and to provide the valve means 24 on the filter element 12 accordingly.
If, as shown in FIG. 4, the valve element 26 of the valve means 24 forms an essentially closed membrane surface, when the filter element is replaced and insertion of a new filter element 12 is forgotten, the valve means 24 cannot be pushed by the trigger part 28 of the filter element 12 as shown in FIG. 1 into its open position, but remains in the closed valve function with the result that a reporting or control means would immediately relay an error report to the operator to indicate that the filter element 12 to be inserted for reliable operation of the system is lacking. In this way dirt damage caused by lack of filtration within the hydraulic circuit can be reliably avoided. Another approach for a functional valve means 24 is given by the embodiment as shown in FIGS. 5 and 6. There, in the closed position as shown in FIG. 5, between the parts of the spiral arm 32 there is a choking passage site 62 which both in the opened position of the spiral spring valve as shown in FIG. 6 and also in its closed state as shown in FIG. 5 enables a choked fluid flow coming from the middle channel 16 in the direction of the fluid discharge 18. Due to this fluid passage point, the hydraulic function can be further maintained; a fouling indicator which is not detailed and which operates based on pressure difference detection would however be able, in the absence of the filter element 12 and accordingly with the closed spiral spring valve configuration as shown in FIG. 5, to signal the pertinent system state as fouling in order to compel filter element replacement in which it is then established that the element 12 is not in its place in the housing part 10.
These pressure difference-controlled fouling displays are easily commercially available in a plurality of versions, and when a working new filter element has been inserted, the pressure difference to be detected between the fluid supply 14 and the fluid drain 18 in the ideal case is near 0. As fouling increases, the pressure difference value then increases until the fouling indicator suggests replacement of the used filter element 12. A comparable pressure difference situation arises when the helical spring valve as shown in FIG. 5 remains closed without the filter element 12 inserted and choked fluid flow takes place only by way of the passage point 62. As a result of the spring elastic configuration of the respective spiral arm 32 it is moreover ensured that on the top of the filter element 12 a type of adjustment force is applied which presses the respective filter element 12 in the direction of the bottom part of the filter housing part 10; this likewise contributes to an increase of operating reliability.
The other embodiment of the valve element 26 shown in FIG. 7 for the valve means 24 has the particularity that in addition to the spiral arm 32, a fixing ring 64 is molded on in one piece to the outside and has two continuous points of application 66 for an actuating tool which is not detailed, designed as spreading pliers with which it is possible to again detachably fix the valve element 26 as a snap ring in an assignable engagement groove 68 (compare FIG. 1) in the head-side filter housing part 20. In this configuration as shown in FIG. 7, the valve element 26 in turn in the middle has an engagement opening 70 for possible passage of the contact-making and pushing pin 54 (compare FIG. 3).
Another desirable side effect in the described configuration of the filter device is that a type of key port system is achieved, i.e., for obtaining a serviceable filter device for a hydraulic circuit it is necessary for the filter element 12 to have the indicated trigger solution 28; otherwise malfunctions on the hydraulic system occur. Since fundamentally knockoffs are being found to an increased degree in the replacement parts business and are often of lower quality, which the user cannot easily detect, it is possible in this way for only original filter elements with the trigger part 28 and the fluid housing to be used with special valve technology. Cheap single elements conversely cannot be serviceably used. The bridges 30 with the center ring 56 of the trigger part moreover form a type of capture structure which keeps small parts such as screws, nuts or the like from falling into the interior of the filter element 12.
Patent Application
20080047890
