Filter units are used to separate different types and different sizes of materials from each other, such as impurities or solid particles from liquids, or other different types or different sizes of materials from each other. In the filter unit, the liquid, material or equivalent that is to be filtered is passed through the filter unit and the filtered liquid, material or equivalent is led off in one direction and the impurities or other solid matter are directed in another. The purpose of the filter unit used to filter liquids is to separate impurities and solid matter from the liquid reliably and as effectively as possible. When handling solid materials, the purpose is to separate materials, products or other such substances into different grades of the same material or into different types of material.

The various types of filter elements in filter units are very different in construction. One type of filter unit in general use is a slot filter, in which impurities and solid matter remain in the slots of the filter unit. The problem with these units is the reliable cleaning of the filter unit slots and the efficient and reliable removal from the filter of the filtered materials, impurities and solid matter. There are also filter units containing disc- shaped filter elements, which are mounted in an interlocking manner, but these cannot be used to effectively and reliably clean different materials, for example, liquids.

The purpose of this invention is to introduce a filter unit which eliminates the drawbacks associated with present filter units. In particular, the purpose of the invention is to introduce a filter unit that can be used to effectively remove impurities and solid matter from liquids and to transfer them out of the filter or to separate solid materials from each other. In

addition, the purpose of the invention is to introduce a filter unit that can be manufactured cost effectively.

The purpose of the invention is achieved with a filter unit that possesses the characteristics presented in the appended claims.

In the filter unit according to the invention, the filter elements are plates mounted on axles, which are adjacent and at some distance from each other, and where the distance between them is essentially the same size as the thickness of the plate. When the distance between the plates is such, the plates on adjacent axles are able to move against each other in the gaps. The liquid, material or equivalent which is to be filtered out, flows or passes through the filter unit through the gaps between adjacent plates on the same axle when they are open, or in other words, when the plates on the adjacent axle are not in the gaps. Other material, or in the case of a liquid, impurities or solid matter contained in it, remains in the gaps between the plates on the same axle. However, when the plates mounted in an interlocking position revolve, they effectively clean the gaps between the plates on the adjacent axles. The plates transfer the material, impurities and/or solid matter which is in the gaps away from the gaps and also move forward the particles on top of the plates. This takes place continually, reliably and consistently. The unit therefore cleans itself and is self-cleaning as a result of its own operation. The filter unit according to the invention is open, the filter area is significantly larger than in other filters, and is therefore extremely effective.

The construction of the filter unit is simple and its production costs are favourable. When the axles are situated such that the plates are partly interlocked in every position there are no large gaps at any stage. In this way the unit functions reliably at all times.

When relatively small-sized material and/or impurities are separated from a liquid, a layer of these impurities and solid matter is formed on the plates. This layer also functions as a filter when filtering liquids.

In the advantageous arrangement of the invention, the profile of the plates is mainly square in shape. With this shape it is possible to

effectively clean the accumulated impurities from the gaps, but the liquid can still pass as desired, and in a controlled manner, between the gaps when the cleaning filter element is not in the gap. The square shape can vary in different adaptations. It can be advantageously rectangular- shaped, with long and short sides. In this case, the plates clean the gaps of the plates on the adjacent axle twice during one revolution.

In an additional advantageous arrangement of the invention, the corners of the plates are rounded, which makes their structure more effective.

Other structural aspects, such as the long sides, can also be slightly at an angle.

The distance between adjacent axles and the size of the plates is advantageously such that the plates are, when in their furthest position, in the immediate vicinity of the adjacent axle. In this manner the plates clean the gaps effectively throughout the whole movement.

In one advantageous arrangement of the invention the filter unit also includes a power unit, which is connected to the axles via a power transmission system in order to rotate the axles. The power transmission system includes connecting rods attached to both sides of the housing, to which the ends of the axles are attached. This kind of structure based on connecting rods facilitates the effective transfer of power and the sure and reliable operation of the axles and filter elements.

In the following, the invention is defined in more detail with reference to the attached illustrations, in which: Figure 1 shows an arrangement of the filter unit according to the invention, viewed from the side, figure 2 shows the filter unit according to figure 1, viewed from above, figure 3 shows the construction of a different arrangement of the filter unit according to the invention, viewed from the side, figure 4 shows the construction according to figure 3, viewed from above, figure 5 shows the details of the construction shown in figure 4 on a larger scale.

figure 6 shows the construction shown in figure 3, to which has been attached connecting rods, viewed from the side,

figure 7 shows the construction shown in figure 6, viewed from above, figure 8 shows an arrangement of the filter element, viewed from the side, figures 9 and 10 show the individual details of the construction of an arrangement of the unit according to figure 3, viewed from the side and above, and figures 11-16 show the different stages of the rotation of the filter elements, viewed from the side.

In the arrangements shown in the figures, the filter unit includes a housing 1 and the axles 3 located within it, the plate-type filter elements 4 mounted on the axles, and the motor 5 at some distance away from the axles. The axles are attached at regular intervals from each other to a frame 6 attached to the housing. The number of plates and axles can vary in different arrangements of the invention in the desired and appropriate manner.

The rotational speed of the plates can be regulated as desired by the motor 5, which is connected by the power transmission system 2 to the axles 3 in the appropriate manner. In the arrangements shown in figures 1 and 2, a chain or equivalent method has been used as the power transmission system. In the arrangements shown in figures 3-7 the motor is connected by means of the flange wheels 2 on the sides of the frame and the shafts 10 to the connecting rods 9, and the connecting rods 9 are arranged so as to turn the axles. The flange wheels 2 are located at both ends of the housing and the shafts 10 are connected to the flange wheels at a point some distance from centre point of the flange wheels. The flange wheels on different sides are connected together by the axle 11.

The connecting rods 9, attached to the ends of the axles, are attached to the shafts 10. The connecting rods 9 are formed from a bar 9, which has been bent into a slight S-shape. One end of the bar is attached to the end of the axle and the other end is attached to a centre pin 12 or equivalent, which is, in turn, attached to the shaft 10.

The plates 4, which function as the filter elements, are attached to the axles 3 at intervals approximately equal to the thickness of the plates. A collet or other such spacer is advantageously placed between the plates.

The axles are, in turn, attached to the frame 6 at a distance which is slightly larger than the distance between the farthest corners of the plates 4 and the axle 3 and collet. The distance between the axles is large enough that the plates can turn and do not contact the adjacent axles or the collets on them, but the plates do, however, extend right into the immediate vicinity of the collets on the axles.

The size and thickness of the plates can vary in different arrangements.

When filtering liquids the thickness of the plates can be even 0.1 mm or larger, and are advantageously around 0.5 mm or larger. When separating solid materials the thickness of the plates can be, for example, 1 mm or larger. The thickness of the plates determines the width of the gap between them because the plates have to rotate in an interlocking manner. The gaps between the plates function as filter slots and their width determines the size of the impurities and solid matter that pass through them.

The plate-type filter elements 4 are mainly rounded rectangular shapes, as shown in the arrangements shown in figures 9 and 11-16. The plates have a hole in the centre for the axle. Other shapes of the plates can also be used in other arrangements of the invention. In the arrangement shown in figure 8 the long sides of the plate are slightly angled so that the outer edge of the plate is thinner than the centre. The shape of the elements on adjacent axles is identical. The plates attached to the outer axles are an exception, and are round-shaped as shown in figure 9. In this case, there is a plate or equivalent fixed between them and the frame so that impurities do not pass through the filter unit.

When the filter unit is being used to filter liquids, the liquid to be filtered is fed into the filter unit from above, or elsewhere, so that it reaches the filter elements. The filter unit can be piaced in different positions with respect to the flowing liquid, but one advantageous position is the sloping position shown in figure 1. In this arrangement the plates are rotated so that they rotate in a clockwise direction according to the figure, in other words the plates transfer the impurities in an upward direction. The impurities can be removed from the filter via the opening 8. It is also possible to rotate the plates in the other direction, when they

transfer the impurities downwards. The outlet pipe 7 is at the bottom of the housing, through which the filtered liquid is removed from the unit.

Figures 11-16 show the operation of the filter elements when using the filter unit. When the motor 5 is started, the power transmission system transfers the motion to the axles, the axles 3 start to rotate and they turn the plates 4. In this case, all the plates rotate clockwise. The plates are positioned, according to the arrangement shown in the figures, so that the plates on adjacent axles are always at right angles to the others.

Other respective positions can also be used. When the plates turn, they clean the gaps between the plates on the adjacent axles and, at the same time, lift the impurities and solid matter on top of the plates. The gaps are partly open so that the liquid to be filtered or equivalent passes via these open gaps through the filter unit. The impurities then remain in the gaps and, in the next stage, the plates move them away from the gaps and along the structure out of the unit.

When separating solid materials, the filter unit is used in the above- mentioned manner arranged for the situation in which solid material of pre-determined size passes through the gaps but material exceeding this size does not pass through them. In this way the material passing through the gaps is separated from the material that remains on the filter elements and is removed. This can be adapted to different applications in which materials or products of pre-determined size are separated from each other from the flow of the material.

In another arrangement of the invention, the filter elements used in the filter unit can be formed from two or more axles and plates, which are positioned on top of each other.

The invention is not limited to the advantageous arrangements shown but can vary within the framework of the invention concept formed by the claims.