This invention concerns a cleaning device and method or, more precisely, a cleaning device and method with which it is possible to effectively clean moving conveyor belts and webs, including ordinary conveyor belts, but also including larger conveyor belts such as the wire of a paper machine, which until now have proved difficult to clean effectively.

Regardless of the purpose for which a conveyor belt is used, it gathers various impurities, sometimes slowly and sometimes more quickly. In any case, conveyor belts must be cleaned, some by a continuous or nearly continuous process and others now and again.

Until now, conveyor belts have been cleaned mainly by jets of compressed air or water.

Washing the belts with water is not suitable in all cases, and always causes difficulties due to the fairly large amounts of water involved. On the other hand, the use of a compressed air jet is a particularly inefficient way of cleaning.

The purpose of this invention is to achieve an improvement on the above-mentioned cleaning methods and devices, by maximizing cleaning effectiveness, facilitating the separation of impurities and the recycling of air, and minimizing the device's total need for power.

These and other benefits and advantages of the invention are achieved by a method and device whose characteristic features are presented in the appended claims.

The invention is described in more detail in the following, with reference to the appended drawing showing the principles on which a device

according to the invention is based, in a certain embodiment of the invention. The method will become apparent by way of the drawing of the device.

Although the invention is not limited solely to the embodiment presented here as a drawing, the drawing nevertheless well describes the principles of the invention. Other embodiments of the invention are presented at the end of this descriptive section.

Device 1, therefore, is formed in principle of two parts, a blowing part 2 and a suction part 3. In the blowing part, an air flow is caused in the normal way by overpressure, while correspondingly the suction part is affected by underpressure. The amount of underpressure is not necessarily the same as the amount of overpressure.

The blowing part is equipped with a pipe system 21 which feeds air to device 1. As is explained in the following, the pipe system is formed of a number of pipes, each of which feeds its own blowing "box" 23-26. Each pipe 21 also includes a valve 22 whose purpose is to open or close the air flow as instructed.

Correspondingly, the suction part 3 is equipped with a pipe system 31 , consisting of the same number of pipes as in the pipe system 21 , with valves 32 arranged in the same way as in the blowing part, and suction "boxes" 33-36, the number of which equals that of the blowing boxes. In addition, the sides of the suction boxes 33-36 may be equipped with a suitable bristle row 37, if so desired. The bristle row 37 controls the suction airflow and allows a certain degree of vertical movement in belt 4 without negatively affecting the suction efficiency.

In this embodiment the belt, web or wire 4 travels between the blowing boxes 23-26 and their corresponding suction boxes 33-36. The boxes are relatively near to and opposite each other. The valves and other

operations are controlled and directed by the control centre 5.

A common disadvantage, and one which negatively affects operating conditions, especially in the case of broad belts, is that it is impossible t get equipment to work properly if it is necessary to use a cleaning devic designed, for example, to clean belts that are many metres wide, with compressed air. This is solved by the invention by dividing the width of the belt into parts, where each part is a sector, 23,33; 24,34; 25,35 and 26,36, as shown in the drawing, comprising a blowing part and a corresponding suction part. Only some, and frequently only one, of the sectors will operate at a time.

By opening a pair of valves 22 and 32 while the other pairs are closed, it is possible to achieve a well-controlled blowing and suction air flow through this sector. When the cleaning process has occurred for the desired length of time, the open pair of valves is closed and simultaneously a second pair of valves is opened, so that the cleaning is transferred to a second sector, and so on. Thus the device may be used to clean belt 4 sector by sector, by continually changing the cleaning sector. The volume of air used can be closely controlled and the requirements for size and power of the equipment are reasonable. If the equipment has enough power, it is possible to use two or more sectors simultaneously, with only some of the sectors being out of use.

The embodiments presented above presuppose that the belt to be cleaned is of a type which lets an air current pass through it to the desired extent. Otherwise the blowing and suction parts operating in different parts of the belt could not carry out their work in pairs.

It is possible, however, to arrange the operation so that the blowing part 2 and the suction part 3 are situated consecutively on the same side of belt 4. Then it will work so that the dirt and impurities loosened by the air of the blowing part 2 will be vacuumed, in the travelling direction of

the wire, by the suction part 3, located either before or after the blowing part 2, in a way corresponding to that which has just been described, but now only from the side occupied by the boxes of the blowing part. The box pairs still operate one after the other, and the cleaning occurs on only a part of the web or belt width.

A third alternative is that the "box pairs" are only one in number, and that this pair is moveable across the belt 4, so that part of the belt is continually being cleaned by one and the same device, in such a way that the device changes its place. This same inventive concept applies to all three solutions.