Abstract:
A filter device includes at least one filter element ( 10 ) housed in a filter housing ( 22 ) and connected for the flow of fluid by fluid connections ( 30, 36 ) to a fluid device, in particular in the form of a hydraulic tank ( 40 ), using a connector device ( 44 ). A plunger valve arrangement is achieved, whereby the connector device ( 44 ) is provided with at least one longitudinally-displaceable blocking piece ( 46 ). In the blocking position, the blocking piece blocks the provided fluid connections ( 30, 36 ). After displacement into an open position, it releases the fluid connections. A blocking or releasing of the fluid connections in a rapid operation process is permitted to carry out a filter element exchange for the used filter medium.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a filter device with at least one filter element held in a filter housing, connected to carry fluid by fluid connections to a fluid means, especially in the form of a hydraulic tank, by a connecting device. 
     BACKGROUND OF THE INVENTION 
     These filter devices are readily available on the market in a plurality of designs and versions. Among their functions is to filter dirt in fluids, such as hydraulic oil, out of these fluids. Hydraulic oil is fouled during installation and when the respective hydraulic system is started up. In addition to this initial fouling, fouling during operation can occur, for example by penetration of dirt at the hydraulic tank due to inadequate tank ventilation, pipe penetrations, piston rod seals, and the like. To the extent fouling within the fluid stored in the hydraulic tank occurs in hydraulic systems of machines such as earth moving machines, excavators or the like, it can be advantageous to implement filtration directly in the area of the hydraulic tank, for example by attaching the filter device directly to the tank. The hydraulic oil removed from the tank is delivered directly to a filter element to filter out dirt which filter element is held in the filter housing. The fluid which has been cleaned in this way then returns again to the tank by the filter housing. Here add-on solutions are known in which the filter device cleans only the contents of the tank. Solutions are also conceivable in which the filter device delivers the correspondingly filtered and cleaned fluid to the hydraulic circuit of the machine, in order from there to return to the tank the fluid fouled with solid particles in the pertinent circulation in the hydraulic circuit. 
     Where the filter device filters only the contents of the tank, fluid is removed from the tank, filtered and then returned again to the tank. To avoid interruptions in the operation of the respective hydraulic system, the contents of the fluid means, especially in the form of a hydraulic tank, is advantageously blocked off relative to the filter housing to replace a fouled and used filter element by a new one, or for changing this filter element to completely dismount the filter housing with the used filter element from the fluid means in the form of the tank. After appropriate maintenance of the unit of the filter housing with the filter element, especially by replacement of the used filter element by a new one, this unit can be re-connected to the fluid means for use. It is also possible to connect a new unit of the filter housing with the unused filter element to the fluid means, while in the other dismounted unit the filter element is changed. For this reason, in the known solutions the pipes must be separated from each other in a complicated manner, sealed, and by complex rotary slide valve parts, the fluid connection between the fluid means (tank) and the filter housing with the filter element must be separated and later re-connected. The rotary slide valve parts, as a component of a connecting means between the filter housing and the fluid means, are not only expensive to produce and complicated to maintain, but also entail the danger that correspondingly large amounts of fluid will emerge from the fluid means as a leaking oil flow. This leakage leads to fouling problems in the vicinity. These solutions are also prone to failure in operation. In this regard, they are less reliable, since an operator often has problems at the assumed position of the rotary slide valve parts in recognizing whether they are in their blocking or in their open position. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved filter device meeting the above described requirements for their operation in a space-saving and reliable manner with low production, installation and maintenance costs. 
     This object is achieved by a filter device having connecting means provided with at least one longitudinally displaceable blocking part which blocks the fluid connection in a blocking position. After displacement into the open position, the fluid connection is cleared. A blocking slide valve is implemented making it possible to block or clear the fluid connections with only a brief actuation process to change the filter element for the used filter medium and to re-use the filter element stored in the filter housing for the filtration tasks under consideration. Since it can be seen from the outside, the operating position of the blocking slide valve is also evident to an operator, which operating position the filter device currently assumes. Based on the configuration of the blocking part as a longitudinally displaceable blocking slide valve, it requires little installation space and can be easily used for cramped installation conditions. The linear displacement motion of the blocking part can be mechanically controlled easily and effectively. This arrangement helps reduce the production, installation and maintenance costs. Operation of the connecting device as the blocking and clearance means, even under difficult ambient conditions, is achieved. 
     With the filter device of the present invention, it is possible to separate the unit formed from the filter element and the filter housing from the remaining fluid means in a fluid-tight manner, in order to replace the used filter element with a new one on site, that is to say, on the fluid means. By preference, the possibility also exists of completely removing this unit from the fluid means, and to replace the element elsewhere. Then additional maintenance operations can be carried out. The change of the element takes only seconds. With the present invention, it is also ensured that fluid (oil) cannot escape to the exterior, leading to environmental pollution. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings which form a part of this disclosure: 
         FIG. 1  is a side elevational view in section of the important components of a filter device, with the filter housing and filter element being separated from the fluid means according to an embodiment of the present invention; 
         FIG. 2  is a side elevational view in section of the filter device of  FIG. 1 , in the assembled state; and 
         FIGS. 3A-3C  are perspective views of the filter device of  FIGS. 1 and 2 , with  FIG. 3A  showing the filter housing separated from the fluid means,  FIG. 3B  showing the filter device assembled and blocked, and  FIG. 3C  showing the filter device assembled and open. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The filter device shown in the figures has a cylindrical filter element  10  of conventional design. The filter element  10  is used to filter dirt, especially in the form of solid particles, out of a fluid flow, such as a hydraulic medium. For this purpose, the filter element  10  is provided with a preferably pleated filter mat  12  supported on the interior on a perforated support tube (not shown). Furthermore, the filter mat  12  is cylindrical, and held between two end caps  14 ,  16 . This element structure is conventional and prior art, so that it will not be described further. The upper end cap  14  can be equipped with a bypass means, for example a bypass valve (not shown) to ensure that when the filter element  10  is clogged with dirt the fluid flow can freely pass the filter element  10  via the end caps  14 ,  16  to avoid obstacles in operation of a fluid or hydraulic system. The lower end cap  16 , as viewed in  FIG. 1 , is held along one cylindrical mounting connection piece  18 , and is sealed via a gasket  20  against the latter. 
     The filter element  10  can be held in a cylindrical filter housing  22  by the mounting connection piece  18 . To replace the fouled filter element  10  with a new filter element  10 , the filter housing  22  on its top has a removable cover part  24  which is otherwise sealed against the interior of the remaining filter housing  22  by another gasket  26 . The essentially cylindrical filter housing  22  tapers downward, as viewed in  FIG. 1 . In the area of this taper  28 , housing  22  has a fluid connection  30  connected to the interior of the filter element  10  to carry fluid via the mounting connection piece  18 . The longitudinal axis  32  of the fluid connection  30  extends at a right angle to the longitudinal alignment or longitudinal axis  34  of the filter housing  22 . Another fluid connection  36  with a longitudinal axis  38  is located on top of fluid connection  30  and is likewise perpendicular to the longitudinal axis  34  of the filter housing  22 . The diameters of the two fluid connections  32 ,  36  correspond or are equal to each other, with the fluid connection  30  forming the fluid outlet and the fluid connection  36  forming the fluid inlet of the filter device. The dirty fluid flows via the fluid inlet  36  into the interior of the filter housing  22  and from there flows from the outside to the inside through the filter element  10  with its filter mat  12 . Any dirt in the fluid flow, especially in the form of solid particles, adheres to the filter mat  12 . The cleaned fluid travels via the interior of the filter element  10  and the mounting connection piece  18  to the side of the fluid connection  30  and accordingly to the outlet side of the filter device. 
     The two fluid connections  30 ,  36  can be connected to a fluid means or container, especially in the form of a hydraulic tank  40 . In the figures, of the hydraulic tank  40 , only one part in the form of the front connecting plate  42  is shown. By a connecting device  44 , the unit of the filter housing  22  and the filter element  10  can be coupled to the fluid means, preferably in the form of a hydraulic tank  40 , and detached again. The connecting device  44  is provided with a blocking part  46  which can be displaced or can slide tranlationally in the longitudinal direction, and is located between and accessible from exterior surfaces of the filter housing and the fluid means. Blocking part  46 , in the blocking position (compare  FIGS. 1 and 3A  and B), blocks the fluid connections  30 ,  36 , and after moving into the open position (compare  FIGS. 2 and 3C ) clears these fluid connections  30 ,  36 . 
     The blocking part  46  is a plate-shaped sliding valve part which is guided sealed between the front connecting plate  42  and another or back connecting plate  48  of the connecting device  44  by a sealing device  50 . As already described, one connecting plate  42  is facing the fluid means or the tank  40 , and the other, second connecting plate  48  faces the unit of the filter housing  22  and the filter element  10 . Both the sliding valve part and the two connecting plates  42 ,  48  are essentially rectangular. The sealing means  50  includes a conventional ring seal between the connecting plates  42 ,  48  and the sliding valve part. The sliding valve part is guided in between in the middle as a blocking part  46 . The sealing device  50  extends annularly around the fluid passages  52 ,  54  extending in the two connecting plates  42 ,  48  and having longitudinal axes coaxial to the longitudinal axes  32 ,  38  of the fluid connections  30  and  36 , respectively.  FIG. 1  illustrates the blocking position of the blocking part  46  with fluid passages  52 ,  54  covered by the wall parts  56  of the blocking part. The fluid passages are kept cleared in the open position shown in  FIG. 2 . 
     The two fluid connections  30 ,  36  of the filter housing  22  are oriented in the longitudinal direction of the latter, one on top of the other in the same manner as the fluid passages  52 ,  54  in the connecting plates  42 ,  48  of the connecting device  44 . Between the blocking wall parts  56  of the blocking part  46 , the blocking part has clearance openings  58  which are cylindrical and which in the open position of the blocking part  46  (compare  FIG. 2 ) are congruent with the fluid passages  52 ,  54  of the connecting device  44  so as to carry fluid. In this open position, the longitudinal axes of the holes of the respective connections extend in a line or are coaxial so that no unnecessary edges are formed which could possibly lead to cavitation or swirling. Holes for fluid passage discharge are in a common plane, relative to the outside contour of the filter housing  22  and to the outside contour of the connecting device  44 . The two fluid connections  30 ,  36  of the filter housing  22  are each provided with one valve  60 ,  62 , respectively. The valve disk of one valve  60  located on the fluid outlet  30  projects over the outlet  30  to the outside. The valve disk of valve  62  is located at the fluid inlet  36 , and is integrated into it. Each respective valve disk opens as shown against the action of the resetting force or biasing of a compression spring, and has a convex arch pointed against the direction of flow of the fluid to be triggered. 
     The fluid connections  30 ,  36  of the filter housing  22  are surrounded on the outer peripheral side by flange-like attachment parts  64 . These attachment parts  64  are used to attach the filter housing  22  to the flange parts  66  of the facing connecting plate  48 . The flange parts encompass the fluid connections  53 ,  54 . The filter housing  22  with the filter element  10  can be attached stationary to the connecting device  44  and accordingly to the fluid means in the form of a hydraulic tank  40  by a conventional screw connection. As viewed in  FIG. 3A , the upper attachment part  64  has a locking part in the form of a locking pin  68 . For passage or receipt of this locking pin  68 , the connecting plate  48  has a through hole  70  which can be made congruent with a recess  72  in the blocking part  46 , as soon as the unit is attached to the connecting device  44  and the sliding valve-shaped blocking part  46  has assumed its open position as shown in  FIG. 2  and  FIG. 3C . In this way, a plausibility check is achieved and operating errors are for the most part precluded, since the unit of the filter housing  22  and the filter element  10  can only be attached when the locking pin  68  has engaged the recess  72  from its free end on the front side. The screws of the attachment parts  64  and the flange parts  66  are tightened to complete the attachment process. This catching engagement of the locking pin  68  results in the sliding valve-like blocking part  46  not unintentionally traveling into its closed position as shown in  FIG. 1 . 
     The blocking part  46 , viewed in the figures on its top, has a handle  74  having a through hole into which the operator can fit his hand accordingly. The filter housing  22  on its side facing away from the connecting device  44  has another handle  76  in the form of a knuckle bow via which the unit of the filter housing  22  and the filter element  10  can be easily handled by the operator. The filter housing  22  itself is preferably of an aluminum diecasting. The blocking part  46  can be of a steel or plastic material. 
     With reference to  FIGS. 3A-C , the important operating sequence is described with reference to the filter device of the present invention. 
     As viewed in  FIG. 3A , the blocking part  46  is in its upper blocking position, as also shown in  FIG. 1 . In this blocking position, the continuous wall sections  56  cover the fluid passages  52 ,  54 . On the sides of the fluid means  40  in the form of the hydraulic tank, an operating overpressure of for example 10 bar is to prevail. As a result of the spring force support, the valves  60 ,  62  are closed. The filter housing  22  should have a new, unused filter element  10  with the formation of a new unit. According to  FIG. 3B , an intermediate position is shown there in which the screws of the attachment parts  64  and the flange parts  66  already engage each other, and the locking pin  68  has already penetrated the hole  70  in the connecting plate  48 . The pin free end adjoins the top of the plate-shaped blocking part  46 . At this point the blocking part  46  is moved farther down and then assumes its open position of  FIG. 3C . Since the handle  74  is provided with stop shoulders at the location of the transition to the recess  72 , the stop shoulders are positioned on the respective parts at the top on the connecting plate  48  so that the blocking part  46  is prevented from being able to slip down out of the guide formed between the two connecting plates  42 ,  48 . The recess  72  is now positioned such that the locking pin  68  engages as soon as the screw connections are definitively fixed. This operating or open position is reproduced according to the sectional view in  FIG. 2 . Based on the prevailing fluid pressure on the sides of the fluid means  40 , the valve  62  which is uppermost in  FIG. 2  is pushed open, and dirty fluid can enter the filter device for a cleaning process through the filter element  10 . The cleaned fluid then leaves the filter housing  22  via the other, second valve  60  which opens by the valve disk being pressed in the direction of the fluid passage  52 . 
     For a decoupling process of the unit from the connecting device  44 , the indicated attachment processes proceed in the reverse sequence. The sliding valve-shaped blocking part  46  closes the fluid means  40 . The valves  60 ,  62  reliably close the filter housing  22  with its contents relative to the exterior. The used filter element  10  can now be cleaned at another suitable location or optionally can be replaced by a new element. Since the fluid means is blocked against the exterior by the blocking part  46 , oil cannot escape from the system to the exterior. In another execution of the solution of the present invention, it is also conceivable to decouple the fluid means from the unit and consequently from the filter housing  22  by the blocking part  46 , on site, but, that is to say, directly on the equipment, to replace the element after loosening the cover part  24 . In place of only one blocking part  46 , several blocking parts or sliding valves can also be assigned to each fluid opening and can assume the blocking function. In this respect it is not necessary to shut down the hydraulic system for a replacement or maintenance process. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.