A plate-type filter lubricating oil or the like. The filter includes a cylindrical, rotatable filter element which is to be cleaned in closed condition by flow reversal along a portion of the filter surface. During the normal operation the entire filter surface is to be effectively available. The device includes a rinsing channel wall having a U-shaped profile, one leg of which constantly engages against the filter element and consequently serves as a wiper body during rotation of the element. To clean the filter element, both legs are pressed against the element, so that a rinsing channel results which communicates with a rinse-out opening and represents a back or return flow through the filter surface. A combination of two such filters provides an advantageous device for machines that are continuously operated.

The present invention relates to a plate-type filter for lubricating oil or 
the like, with partial return or back flow for self cleaning. The filter 
includes a cylindrical filter element rotatable in a cylindrical housing 
having an inlet and outlet opening arranged externally of the mantle 
surface of the filter element, which in turn has a rinse-out opening in 
one face plate thereof; a wiper body engages along one mantle region of 
the filter element, and a rinsing channel wall with a U-shaped cross 
section is open toward the rinse-out opening and spans a segment of the 
filter element. 
A plate-type filter of this general type is disclosed by British Pat. No. 
1,113,114. This arrangement has the considerable drawback that the rinsing 
channel wall does not engage sealingly against the filter element, so that 
a continuous leakage oil loss occurs from the outer annular chamber 
externally of the filter element toward the rinsing channel. This effects 
an undesired pressure loss at the filter. A further disadvantage is that 
the surface of the entire filter element is never available for filtering 
purposes, but rather a segment is continuously closed by the wiper body 
and has flow therethrough in the reverse direction from the inside to the 
outside. Consequently, the filter is to be a arranged larger with a 
completely engageable filter insert compared with the foregoing. 
It is an object of the present invention to provide a filter which can be 
cleaned during operation and which in continuous operation has a maximum 
filter surface with respect to the overall dimensions, permits only 
minimum leakage oil losses, and is distinguished by its simple and 
operationally reliable construction.

The filter of the present invention is characterized primarily in that the 
leg of the rinsing channel wall which is to the rear when viewed in the 
direction of rotation, forms the wiper body and is in constant engagement 
with the filter element; furthermore the rinsing channel wall has an 
adjustment member for lifting the front leg from, and pressing it against, 
the filter element; the rinse-out opening is provided with a valve which 
can be opened for the rinsing procedure. 
During continuous operation, the valve at the rinse-out opening is closed, 
and the front edge of the rinsing channel wall is at a distance from the 
filter element. The dirty oil entering through the inlet opening in the 
housing externally of the filter element has access to the entire 
periphery of the filter element and flows through the element at uniform 
pressure distribution over the entire surface. Thus, the greatest possible 
throughput quantity, or the least pressure loss, is provided in an 
advantageous manner at prescribed external dimensions of the filter. The 
filtered oil leaves the interior of the filter at a face surface thereof, 
and suitably enters a collecting chamber after leaving the housing by way 
of and through an outlet. 
In the first operation of cleaning the filter, the filter element is 
rotated by at least 360.degree. in the prescribed direction upon its axis 
by means of a handwheel or the like arranged externally of the housing, 
whereby the dirt deposited externally on the filter elements accumulates 
ahead of the wiper body along the adjoining edge of the rinsing channel 
wall. The filter remains in operation in an unchanged manner with a once 
again cleaned filter element. Preferably directly after this wiping 
procedure, the front edge of the rinsing channel wall is pressed by means 
of the adjustment device against the filter element, and the valve at the 
rinse-out opening is opened. Consequently, the rinsing-out procedure 
starts, according to which the clean oil in the interior of the filter 
element, which clean oil is at a higher pressure compared with the 
rinsing-out return, passes in the region of the rinsing channel as a 
return flow through the corresponding segment of the filter element, 
carrying along the dirt accumulated by the wiper body on out of the 
rinsing channel. During wiping-off of the dirt, there exists the danger 
that individual dirt particles may be pressed into the filter gap, where 
they could settle. This can be eliminated by rotating the filter element a 
further 360.degree. during the rinsing-out procedure, so that rinsing-out 
occurs through every region of the plate-type cylinder. The pressure loss 
subsequently measurable at the filter thus again reaches according to 
measurements the readjusted condition. 
A special advantage of the arrangement of the present invention is that 
first the entire filter surface is completely cleaned again by the wiper 
before, for rinsing out the dirt, the filter surface is reduced slightly 
around the segment adjoining the rinsing channel. The higher pressure loss 
through the reduced filter surface therefore occurs only with a clean 
filter, and is smaller than with an extremely dirty filter element having 
full flow therethrough. After the short rinsing procedure, the valve is 
closed again and the rinsing channel wall is lifted again by the 
adjustment member at the front edge until the next cleaning procedure of 
the filter. 
According to an especially advantageous inventive embodiment of the rinsing 
channel wall and of the adjustment member, a spring supported against the 
housing is arranged externally of the rinsing channel for pressing the 
rinsing channel wall against the filter element; furthermore within the 
rinsing channel or an extension attached to the rinsing channel wall, 
there is located a cam, which is rotatable by an axially parallel rod, for 
lifting the rinsing channel wall from the filter element; and furthermore, 
the movable leg of the rinsing channel wall, at least at the front ends, 
has a guide which slides on pins secured to the housing, or slides along 
an axially parallel rod; the guide is arranged at an angle to the radial, 
and is inclined inwardly toward the rear leg of the rinsing channel wall. 
This provides on the one hand, by means of a rod and cam, a simple 
adjustment member which can cooperate especially advantageously with a 
single curved steel wire in the form of a spring, and on the other hand, 
by means of the inclined arrangement of the guide, there results the 
special advantage for the rinsing-out procedure that the wiping body 
removes itself a short distance from the accumulated dirt during pressing 
into engagement of the rinsing channel wall tangentially against the 
filter element, whereby this dirt lies free in the rinsing channel and the 
danger is reduced that a portion of the dirt is incompletely rinsed-out 
along an edge. In an especially advantageous embodiment, respective 
axially parallel rods or pins are mounted in the face surfaces of the 
filter for holding the spring, for guiding the rinsing channel, and for 
adjusting the cam. The inventive embodiment represents a simple and 
operationally reliable arrangement. 
According to another embodiment of the present invention, the rear leg of 
the rinsing channel wall, which leg acts as a wiper body, in the 
longitudinal section has a surface profile which complements the surface 
profile of a longitudinal section of the plate-type cylinder as far as to 
the filter gap. 
The entire arrangement is preferably provided for wire plate-type filters, 
according to which a smooth edge of the wiping body assures a satisfactory 
wiping on the plate-type cylinder. This is the simplest and least 
complicated embodiment. In so far as a different construction is provided 
in place of a wire net for the plate-type cylinder, for instance discs 
having different diameters and provided with recesses and arranged in 
layers, the surface of the wiper body is correspondingly embodied, for 
instance as a comb which engages the recessed areas of the plate-type 
cylinder. 
Referring now to the drawing in detail, the filter element 1 in FIG. 1 
comprises a rotational axis 2, a carrier star or support 3, and the gap or 
plate-type cylinder 4. The filter element 1 is rotatable relative to a 
face plate 21 of member 20 fixed to the housing; this plate 21 of member 
20, together with a further front face plate 19, carries or supports the 
pins or rods 8, 9, 10, 11. A spring 7 is held by two axially-parallel rods 
10 and 11; this spring 7 presses the rinsing channel wall 6 against the 
filter element 1. That leg 12 of the rinsing channel wall 6 which is to 
the rear when viewed in the direction of rotation, engages the plate-type 
cylinder 4, while the front leg 13 is lifted from the filter element by 
the cam 14 of the adjustment member. The rinse-out opening 17 is arranged 
in the face plate 20 and, axially viewed, inside the rinsing channel 5. 
Dirty oil from outside the plate-type cylinder 4 enters the plate-type 
filter through a non-illustrated inlet in the housing; the dirty oil flows 
through the filter element from the outside to the inside over the entire 
periphery thereof. If a predetermined time of operation has elapsed, or 
the greatest permissible degree of filter contamination or dirtiness has 
occurred, the filter element 1 is rotated in the direction indicated by 
the arrow at least 360 degrees upon the rotational axis 2. In so doing, 
the dirt deposited on the plate-type cylinder 4 collects on the wiper 
body. 
FIG. 2 shows the second phase of the cleaning procedure, according to 
which, by rotating the cam 14 with the rod 8, also the front edge 13 of 
the rinsing channel wall 6 is brought by spring 7 into engagement against 
the plate-type cylinder 4, the latter being designated in a lower left 
corner of FIGS. 1 and 2 as well as in FIG. 3. As a result, the rinsing 
channel 5 as such is closed off, and in the particular section of the 
plate-type cylinder 4 being handled, dirty oil no longer flows in. After 
opening the valve 18 at the rinse-out opening 17, there occurs in this 
segment a reversed through-flow from the interior of the plate-type 
cylinder 4 into the interior of the rinsing channel 5 and toward the 
rinse-out opening 17. During a pivoting away of the cam 14 from the 
extension 15 on the rinsing channel wall 6, this wall moves along a path 
prescribed by cooperation of the guide rod 9 and the guide 16. This radial 
movement of the guide 16 simultaneously generates a tangential movement, 
whereby the wiper body is moved away from the collected dirt in the 
direction of rotation. Consequently, accumulation of the dirt in the edge 
formed by the plate-type cylinder and the wiper body is avoided. After 
rinsing out the dirt, which can be enhanced by a further rotation of the 
plate-type cylinder by 360.degree., the reverse flow is interrupted by 
closing the valve 18 and, by rotating the adjustment member, the normal 
filter flow is re-established again also in the region of the rinsing 
channel 5. 
FIG. 3 shows the face plate 20, an oppositely located second face plate 19, 
and the plate-type cylinder 4 which is rotatable relative thereto. The 
rinse-out opening 17 is in the left face plate 20, with the valve 18 
therebehind. The end surfaces of the face plates are fixed at a distance 
from one another corresponding approximately to the length of the rinsing 
channel wall 6. The face plates, which are fixed to the housing, are 
normally not themselves parts of the housing, but rather are only the 
supports for the rotational axes as well as for the rods 8, 9, 10, 11; 
these face plates are embodied in such a way as to be removable as a unit 
with the filter element 1 from the housing of the filter. Consequently, 
the rinsing channel wall 6 does not have to be repositioned relative to 
the filter element 1 after inspection of the filter element for damage or 
the like. 
FIG. 2A has primes added to reference numeral designations corresponding to 
those of FIGS. 1, 2 and 3; one lamination or disc 23 is visible to the 
left though partially broken away to show another lamination or disc 22 to 
the right thereof. 
As shown in FIG. 4, the surface of the wiper body, i.e. the rear leg 12' of 
wall 6', need not necessarily be smooth. Rather, this surface can 
correspond to the configuration of the plate-type filter. Thus, for 
example, if the filter is comprised of lamination or discs 22 and 23 
having different diameters, the correspondingly embodied wiper body 
surface would be in the form of a comb in order to properly engage the 
surface of the filter. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawing, but also encompasses any 
modifications within the scope of the appended claims.