Rotary Strainer

This invention relates to a rotary strainer for separating sludge such as chips and a liquid such as washing or cleaning liquid or oil.

The devices using a filter or a magnet for separating a liquid-solid mixture such as above-mentioned are well known, but none of these known devices could produce a constant satisfactory separating effect either because the filter would become clogged in long time use, lowering the filtering performance or because certain types of sludge material would not be adsorbed or sucked up by the magnet.

It is therefore an object of the present invention to provide a strainer whereby an excellent separating effect can be constantly obtained.

Another object of the present invention is to obtain a strainer which has high throughput capacity and which is free of trouble such as clogging even if it is used for a long time.

The strainer according to the present invention features a primary separating action provided by a filter net stretched over the entire periphery of a revolving box-like structure and a secondary separating action produced by the liquid flow during carriage of the sludge dropped onto a screw conveyor chute having a slant bottom face, said both primary and secondary separating actions being combined to achieve effective and efficient separation of the sludge such as chips and liquid such as washing or cleaning liquid.

The other objects, features and advantages of the present invention will become apparent from the following detailed description of the invention as taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front elevation showing schematically an embodiment of the present invention; and

FIG. 2 is a sectional view taken along the line II--II of FIG. 1.

Referring to the drawings, there is shown a strainer, generally designated 1, comprising a hexagonal box-like structure 2 of which the rear side is closed with a base plate 3 while the front side is opened through a circular opening 4' formed in a plate 4. A filter net 5 is spread over the periphery of the box-like structure. The base plate 3 of the strainer 1 is secured through a cylindrical retainer 3' to a horizontally disposed driving shaft 6 so that the strainer 1 will rotate integral with said driving shaft 6.

The fore end portion of said driving shaft 6 projects out from the opening 4' of the strainer 1 and is provided therearound with a screw 7 that continues from the portion inside the structure 2. Provided below said screw 7 is a screw conveyor chute 8 having a bottom face slanted toward the strainer 1. It is to be noted that the vane diameter of the screw 7 changes successively in its axial direction in accordance with the angle of slant of said conveyor chute 8. The conveyr chute 8 is provided with an upper cover 8'. This upper cover 8' and the fore end of the conveyor chute 8 define a downwardly bent discharge port 9. Provided beneath the conveyor chute 8 is a passage 10 which opens into the box-like structure 2 through the opening 4' and which is designed to introduce the mixture materials such as sludge and liquid therethrough into the inside of said structure 2.

There are also provided a tank 11 and a plurality of partition plates 12 arranged radially in the inside of the structure 2. These partition plates 12 function to positively guide the sludge such as chips in the strainer 1 upwardly with rotation of said strainer 1.

In operation of the present strainer, it is rotated by the driving shaft 6 at the rate of about one rotation per minute in the direction of arrow A and the mixture materials to be separated are introduced into the box-like structure 2 through the passage 10 as shown by arrow B, whereby the liquid such as cleaning liquid or oil is guided into the tank 11 through the filter net 5 spread around the periphery of said structure 2 while the sludge such as chips is reservoired within the structure 2, and thus the primary separation is accomplished by the filter net 5. The sludge reservoired within the structure 2 is guided upwardly by the partition plates 12 with rotation of the strainer 1 until finally it is dropped onto the screw conveyor chute 8. The sludge dropped onto said chute 8 has still attached thereto the liquid such as cleaning liquid or oil, but such liquid is separated from the sludge by the secondary separating action that is performed during carriage by the screw 7. That is, as the bottom face of the conveyor chute 8 is inclined downwardly toward the inside of the structure 2, the liquid such as cleaning oil is obliged to flow to the right in FIG. 2 on the inclined bottom face of the conveyor chute 8 when the sludge is carried toward the discharge port 9 by the screw 7 with rotation of the driving shaft 6, and thereby the liquid is substantially separated from the sludge. Arrangement may be made such that the liquid remaining on the conveyor chute 8 will be flown over the upper edge of the chute, or a suitable hole or holes may be formed in the chute 8 to let the liquid fall down through such hole or holes. The liquid dropped from the conveyor chute 8 is again guided into the tank 11 by passing through the filter net 5.

Needless to say, the sludge discharged out from the discharge port 9 as shown by arrow C is removed by a suitable means. Also, a suitable discharge means is provided in the tank 11 so that the surface of the liquid in the tank will not rise above a certain level.

Preferably, an air nozzle 13 for injecting air is provided immediately above the strainer 1 as shown in FIG. 2. By this means, the sludge particles such as chips adhering to the filter net 5 are forcibly excluded to keep the filter net 5 almost perfectly safe from clogging.

While the present invention has been described by way of a preferred embodiment as illustrated in the accompanying drawings, it should be understood that the present invention can be also embodied in various other forms within the scope of the appended claims.