阅读说明：本技术 过滤装置和用于接通和/或关闭过滤装置的方法 (Filter device and method for switching on and/or off a filter device ) 是由 S·贝尔 M·斯泰金 S·曼斯基 P·瓦特肖特 于 2019-06-26 设计创作，主要内容包括：本发明涉及过滤装置和接通和/或关闭过滤装置的方法。过滤装置用于从待净化气体中分离杂质,包括由盖子和罐组成的过滤器壳体；盖子设有待净化气体的入口和已净化气体的出口；罐中安装有过滤元件,其由顶盖、底盖和顶盖和底盖之间的滤芯组成；顶盖设有入口管道,入口管道入口可连接到盖子入口,使得待净化气体经入口管道进入滤芯；在盖子和顶盖之间有空间,该空间可连接到盖子出口；过滤装置还设置有具有入口端口和出口端口的开关元件,开关元件可旋转地安装在盖子中,开关元件能够在关闭位置和扭转位置之间旋转,在关闭位置中入口端口或出口端口分别连接到盖子的入口或出口,在扭转位置中则非如此并且顶盖的入口管道的入口可连接到盖子的入口。(The invention relates to a filter device and a method for switching on and/or off a filter device. The filtering device is used for separating impurities from gas to be purified and comprises a filter shell consisting of a cover and a tank; the cover is provided with an inlet for gas to be purified and an outlet for purified gas; the tank is internally provided with a filter element which consists of a top cover, a bottom cover and a filter element between the top cover and the bottom cover; the top cover is provided with an inlet pipe, the inlet of the inlet pipe can be connected to the inlet of the cover, so that the gas to be purified enters the filter element through the inlet pipe; a space between the lid and the top cover, the space being connectable to the lid outlet; the filter device is further provided with a switching element having an inlet port and an outlet port, the switching element being rotatably mounted in the lid, the switching element being rotatable between a closed position, in which the inlet port or the outlet port is connected to the inlet or the outlet of the lid, respectively, and a twisted position, in which this is not the case and the inlet of the inlet duct of the top cover is connectable to the inlet of the lid.)

1. A filter device for separating impurities from a gas to be cleaned,

the filter device (1) comprises a filter housing (2) consisting of a cover (3) and a tank (4);

the lid (3) is provided with an inlet (6) for gas to be cleaned and an outlet (7) for cleaned gas;

a filter element (9) is arranged in the tank (4), and the filter element (9) consists of a top cover (10), a bottom cover (11) and a filter element (12) between the top cover and the bottom cover;

the top cover (10) is provided with an inlet duct (17), the inlet duct (17) having an inlet (18), the inlet (18) of the inlet duct (17) being connectable to the inlet (6) of the cover (3) such that gas to be cleaned enters the filter cartridge (12) through the inlet duct (17);

between the lid (3) and the lid top (10) there is a space (21), which space (21) is connectable to the outlet (7) of the lid (3),

characterized in that the filter device (1) is further provided with a switching element (22) having an inlet port (23) and an outlet port (24), the switching element (22) being configured in the following manner:

the switching element is rotatably mounted in the cover (3); and

the switching element is rotatable between a closed position, in which the inlet port (23) or the outlet port (24) is connected to the inlet (6) or the outlet (7) of the lid (3), respectively, and a twisted position, in which this is not the case and the inlet (18) of the inlet duct (17) of the top cover (10) is connectable to the inlet (6) of the lid (3).

2. A filter device according to claim 1, wherein the switch element (22) is a bypass element, wherein the inlet port (23) and the outlet port (24) are in fluid communication with each other through a bypass duct (25) such that the gas to be cleaned can flow from the inlet (6) of the lid (3) to the outlet (7) of the lid (3) when the switch element (22) is rotated to the closed position.

3. A filter device as claimed in claim 2, characterized in that a filter material (26) is provided in the bypass duct (25).

4. A filter device according to claim 1, wherein the inlet port (23) and the outlet port (24) of the switch element (22) are not in fluid communication with each other when the switch device (22) is rotated to the closed position, such that gas to be cleaned cannot flow from the inlet (6) of the lid (3) to the outlet (7) of the lid (3).

5. A filter device as claimed in any one of claims 1 to 4, characterized in that a rotation device (27) for rotating the switch element (22) in the cover (3) is provided, which is designed to be controllable when mounting the cover (3) to the tank (4).

6. A filter device as claimed in any one of claims 1 to 4, characterized in that the rotation means (27) comprise a pin (28), the pin (28) being connected to the switch element (22) or being formed as part of the switch element (22) and extending through the cover (3).

7. A filter device as claimed in any one of claims 1 to 4, characterized in that blocking means (32) are provided for blocking the cover (10) with respect to the switch element (22), the blocking means (32) being arranged such that the cover (10) rotates together with the switch element (22).

8. A filter device as claimed in any one of claims 1 to 4, characterized in that the inlet port (23) of the switch element (22) is provided with a non-removable seal (33) on the side closest to the inlet (6) of the cover (3) in the closed position and/or the outlet port (24) of the switch element (22) is provided with a non-removable seal (33) on the side closest to the outlet (7) of the cover (3) in the closed position.

9. A filter device according to claim 8, characterised in that the seal (33) on the inlet port (23) and/or the outlet port (24) is cast into a recess provided for it, so that the seal (33) is part of the switch element (22).

10. A filter device according to claim 8, wherein the seal (33) on the inlet port (23) and/or the outlet port (24) is made of a thermoplastic elastomer.

11. A filter device as claimed in any one of claims 1 to 4, characterized in that the switch element (22) is made of metal.

12. A filter device as claimed in any one of claims 1 to 4, characterized in that an indication or display device (29) is provided which is configured to indicate or display whether the switch element (22) is in the closed position or in the twisted position.

13. A filter device as claimed in any one of claims 1 to 4, characterized in that the inlet (6) of the cover (3) is provided with a rounding or chamfer on the side closest to the inlet port (23) of the switch element (22) in the closed position and/or the outlet (7) of the cover (3) is provided with a rounding or chamfer on the side closest to the outlet port (24) of the switch element (22) in the closed position.

14. A filter device as claimed in any one of claims 1 to 4, characterized in that the cover (3) is provided with a recess on at least one of its two opposite sides, which in the twisted position is closest to the inlet port (23) and the outlet port (24) of the switching element (22), respectively.

15. A filter device according to claim 14, wherein the recess is a gradual recess in a direction coinciding with a tangential direction in which the switching element is rotatable.

16. A method for switching off and/or on a filter device (1) for separating impurities from gas to be cleaned,

the filter device (1) comprises a filter housing (2) consisting of a cover (3) and a tank (4);

the lid (3) is provided with an inlet (6) for gas to be cleaned and an outlet (7) for cleaned gas;

a filter element (9) is arranged in the tank (4), and the filter element (9) consists of a top cover (10), a bottom cover (11) and a filter element (12) between the top cover and the bottom cover;

the top cover (10) is provided with an inlet duct (17), the inlet duct (17) having an inlet (18), the inlet (18) of the inlet duct (17) being connectable to the inlet (6) of the cover (3) such that gas to be cleaned enters the filter cartridge (12) through the inlet duct (17);

between the lid (3) and the lid top (10) there is a space (21), which space (21) is connectable to the outlet (7) of the lid (3),

characterized in that the filter device (1) is further provided with a switching element (22) having an inlet port (23) and an outlet port (24), wherein the switching element (22) is rotated in the lid (3) between a closed position, in which the inlet port (23) or the outlet port (24) is connected to the inlet (6) or the outlet (7) of the lid (3), respectively, and a twisted position, in which this is not the case and the inlet (18) of the inlet duct (17) of the top cover (10) is connectable to the inlet (6) of the lid (3).

17. Method according to claim 16, characterized in that the cover (10) is rotated together with the switching element (22) by blocking the blocking means (32) of the cover (10) with respect to the switching element (22).

18. Method according to claim 16 or 17, characterized in that the switching element (22) is rotated in the lid (3) by means of a rotating device (27), wherein the rotating device (27) is controllable when mounting the lid (3) on the tank (4).

19. Method according to claim 16 or 17, characterized in that the indication or display means (29) are used to indicate or display whether the switching element (22) is in the twisted or in the closed position.

Technical Field

The invention relates to a filter device and a method for switching on and/or off a filter device.

More specifically, the filtering apparatus is used to filter out impurities (such as oil and dust) from a gas (such as compressed air).

Background

Known filter devices include a filter housing in which a filter element can be placed. The filter housing comprises a lid and a canister containing the filter element, the lid typically being screwed onto the canister or connected to the canister by a bayonet fitting.

The lid is provided with an inlet for gas to be cleaned and an outlet for cleaned gas.

The filter element itself comprises a top cap, a bottom cap and a filter element between the top cap and the bottom cap, the filter element consisting of a filter material.

The top cover is provided with an inlet duct which can lead the gas to be purified to the inside of the filter cartridge. The filter element may be mounted such that the inlet of the inlet duct is connected to the inlet of the cover, so that the gas to be purified flowing into the filter device via the inlet of the cover is guided to the filter element.

Between the cover and the top cover there will be a space which is connected to the outlet of the cover, so that the gas which has passed through the filter element can leave the filter device through the space and the outlet.

It is well known that the design of the inlet duct in the head cover will play an important role in the pressure drop in the filter device.

It is well known that over time the cartridge becomes saturated and needs to be replaced.

For this purpose, the machine using the filter device will be shut down. Next, the canister may be removed from the lid, and the filter element may be removed from the canister. A new filter element is then placed in the canister and the canister is reattached to the lid.

This has the disadvantage that the machine must be stopped and then restarted. For example, if the machine is a compressor, the supply of compressed gas is stopped, which is undesirable for consumer applications that continuously require compressed gas.

Furthermore, for most machines, the number of restarts should be limited as much as possible, since this would lead to wear of the machine.

In order to limit the number of restarts and interruptions of the compressed gas supply, solutions have been established in which a bypass line is arranged in parallel with the filter device and externally, with the necessary additional piping and shut-off valves, to allow the filter device to be bypassed so that it can be taken out of operation for replacing the filter element without interrupting the machine.

Sometimes, an additional filter is provided in the bypass line to ensure that the gas passing through the bypass line is still more or less purified of contaminants during replacement of the filter element.

However, the additional piping and shut-off valves result in an additional pressure drop and an additional risk of gas leakage, which may have an impact on the energy efficiency of the machine.

Furthermore, the additional piping and shut-off valves create additional filter installation complexity, which means higher installation costs, larger filter installation size, and longer filter installation time than filter installations without these additional piping and shut-off valves.

Disclosure of Invention

The present invention aims to provide a solution to at least one of the above and/or other drawbacks by providing a filter device that enables the closing and/or switching of the filter element without the need for additional valves and possible piping.

The subject of the invention is a filter device for separating impurities from a gas to be purified,

the filter device comprises a filter housing consisting of a cover and a tank;

the lid is provided with an inlet for gas to be cleaned and an outlet for cleaned gas;

a filter element is arranged in the tank and consists of a top cover, a bottom cover and a filter element between the top cover and the bottom cover;

the top cover is provided with an inlet duct having an inlet, the inlet of the inlet duct being connectable to the inlet of the cover such that gas to be purified enters the filter cartridge through the inlet duct;

between the lid and the top cover there is a space, which is connectable to the outlet of the lid,

characterized in that the filter device is further provided with a switching element having an inlet port and an outlet port, the switching element being configured in the following manner:

the switch element is rotatably mounted in the cover; and

the switching element is rotatable between a closed position, in which the inlet or outlet port is connected to the inlet or outlet, respectively, of the lid, and a twisted position, in which this is not the case and the inlet of the inlet duct of the top cover is connectable to the inlet of the lid.

The advantage is that by integrating the switch element in the cover of the filter device, the filter device can be deactivated without additional shut-off valves by rotating the switch element to the closed position, after which the canister can be removed for replacing the filter element without releasing raw gas to the environment.

In a preferred embodiment of the invention, the switching element is a bypass element, wherein the inlet port and the outlet port are in fluid communication with each other through a bypass duct, such that gas to be cleaned can flow from the inlet of the lid to the outlet of the lid when the switching element is rotated into the closed position.

An advantage of this embodiment is that the filter element can be replaced without having to shut down the machine, since the gas to be cleaned will flow through the lid via the bypass element.

Furthermore, there are no additional conduits and shut-off valves, thus avoiding the associated disadvantages.

Preferably, a filter material is provided in the bypass duct, so that the gas to be cleaned is still more or less cleaned of contaminants, even if the filter device is bypassed when the bypass element is rotated into the closed position.

In an alternative design, the inlet port and the outlet port of the switch device are not in fluid communication with each other when the switch device is rotated to the closed position, such that gas to be cleaned cannot flow from the inlet of the lid to the outlet of the lid. Thus, when the switch element is rotated to the off position, the filter element can still be replaced in a correct and safe manner.

Preferably, blocking means are provided to block the cap relative to the switching element such that the cap rotates with the switching element.

This will cause the cap and the switch element to rotate together, so that either the cap will be connected to the inlet of the lid or the switch element will be connected to the inlet of the lid, depending on the position of the switch element.

This has the advantage that both the cover and the switch element are in the correct position by one action, so that the filter device can be easily switched on or off in a correct and safe manner.

Alternatively, it is also possible, for example, to rotate the cover and then the switching element. This of course requires two actions and may also lead to errors.

In a practical form of the invention, the inlet and outlet ports of the switching element are provided with non-removable seals.

This has the advantage that the sealing between the inlet and outlet ports and the lid inlet and lid outlet, respectively, will be very good, so that no leakage occurs.

The mechanical or chemical connection between the seal and the switching element is very important to ensure that the seal is not damaged or loosened during rotation of the switching element.

Therefore, it is preferred to use a non-removable seal, instead of e.g. a removable O-ring placed in a correspondingly provided groove, because the O-ring tends to loosen during rotation.

The invention also provides a method for switching off and/or on a filter device for separating impurities from gas to be cleaned,

the filter device comprises a filter housing consisting of a cover and a tank;

the lid is provided with an inlet for gas to be cleaned and an outlet for cleaned gas;

a filter element is arranged in the tank and consists of a top cover, a bottom cover and a filter element between the top cover and the bottom cover;

the top cover is provided with an inlet duct having an inlet, the inlet of the inlet duct being connectable to the inlet of the cover such that gas to be purified enters the filter cartridge through the inlet duct;

between the lid and the top cover there is a space, which is connectable to the outlet of the lid,

characterised in that the filter device is also provided with a switching element having an inlet port and an outlet port, wherein the switching element is rotated in the lid between a closed position, in which the inlet port or the outlet port is connected to the inlet or the outlet of the lid, respectively, and a twisted position, in which this is not the case and the inlet of the inlet duct of the top cover is connectable to the inlet of the lid.

Drawings

In order to better illustrate the characteristics of the invention, some preferred embodiments of the filtering device according to the invention are described below, by way of non-limiting example, with reference to the accompanying drawings, in which:

fig. 1 shows a filter design according to the invention in a schematic perspective view;

fig. 2 shows a cross section according to the line II-II in fig. 1 in a schematic perspective view;

fig. 3 shows the switching element from fig. 2 in a schematic perspective view;

fig. 4 and 5 show in enlarged views the part shown at F4 in fig. 2 in two different positions.

Detailed Description

Fig. 1 shows a filter device 1 according to the invention for separating impurities from a gas.

The gas may be, for example, compressed air, but the invention is not limited thereto.

The impurities may be oil, water and/or dust.

The filter device 1 comprises a filter housing 2, the filter housing 2 consisting of a lid 3 and a tank 4, the lid 3 and the tank 4 being mountable on top of each other to form the filter housing 2.

In the example shown, the can 4 is screwed into the lid 3, wherein both the lid 3 and the can 4 are provided with cooperating threads 5.

It is not excluded that the can 4 is fixed in the lid 3 by means of a bayonet fitting or other means.

The lid 3 is provided with an inlet 6 for gas to be cleaned and an outlet 7 for cleaned gas. Typically, the filter device 1 with the cover 3 is mounted in a pipe of a machine (e.g. a compressor device). For this purpose, the cover 3 is provided with suitable flanges 8 at the inlet 6 and the outlet 7.

In the filter housing 2, more specifically in the tank 4, a filter element 9 is mounted. This is shown in fig. 2, showing a cross-section.

The filter element 9 comprises a top cover 10 and a bottom cover 11 with a filter insert 12 of filter material therebetween.

The bottom cover 11 is optionally provided with means 13 for positioning and/or fixing the filter element 9 in the can 4 in translation in each direction after mounting the can 4 in the cover 3.

The means 13 may be a cavity 14 or a recess which cooperates with a rod 15 provided in the bottom 16 of the tank 4.

Furthermore, the device 13 is designed such that the filter element 9 can be rotated in the tank 4. This means that the filter element 9 can be rotated about an axis in the tank 4.

The detailed figures 4 and 5 clearly show how the cap 10 is manufactured.

The top cover 10 is provided with an inlet duct 17, which inlet duct 17 can lead the gas to be cleaned to the filter cartridge 12 when the top cover 10 is rotated into the corresponding position in the cover 3. From now on, this position will be referred to as "twisted position".

The inlet duct 17 has an inlet 18, which inlet 18 can be connected to the inlet 6 of the lid 3 when the top lid 10 is in a twisted position when the tank 4 is mounted in the lid 3. The inlet conduit 17 also has an outlet 19, the outlet 19 being connected to the interior 20 of the filter cartridge 12.

In the "twisted position" described above, the gas entering the filter device 1 through the inlet 6 must first pass through the filter element 12 before it can leave the filter device 1 through the outlet 7.

As can be clearly seen in fig. 4, there is a space 21 between the lid 3 and the top cover 10, which is connected to the outlet 7 of the lid 3.

The space also accommodates a switching element 22, in this case a bypass element, shown in detail in fig. 3.

The bypass element as the switching element 22 is provided with an inlet port 23 and an outlet port 24, which are connected to each other via a bypass conduit 25, namely: the inlet port 23 and the outlet port 24 are connected to each other via a bypass conduit 25.

The switch element 22 is rotatably mounted in the lid 3 so as to be rotatable between a closed position, in which the inlet port 23 is connected to the inlet 6 of the lid 3 and the outlet port 24 is connected to the outlet 7 of the lid 3, and a twisted position, in which it is not.

In the closed position, gas entering the filter device 1 through the inlet 6 will be able to flow directly to the outlet 7 without having to pass through the filter element 12.

In the twisted position, the inlet 18 of the inlet duct 17 of the top cover 10 will be connected to the inlet 6 of the lid 3.

The outlet 7 of the lid 3 will then be connected to the aforementioned space 21 as described above and no longer to the outlet port 24.

In this example, the switching element 22 is made of metal, but is not excluded from being made of plastic or ceramic material.

The switching element 22 may be manufactured by 3D printing, for example.

A filter material 26 may be provided into the bypass duct 25.

In order to allow the switching element 22 to rotate in the filter device 1, a rotation device 27 is provided for rotating the switching element 22 in the cover 3, the rotation device 27 being designed such that the rotation device 27 is controllable when the can 4 is mounted in the cover 3.

This will allow the switch element 22 to rotate when the filter device 1 is installed in a machine.

In this case, the aforementioned rotation means 27 comprise a pin 28, the pin 28 being connected to the switch element 22 or being formed as part of the switch element 22 and extending through the cover 3. By means of the rotation pin 28, the switching element 22 can be rotated in the lid 3 from the closed position to the twisted position.

In order to give a visual indication of the position of the switch element 22 when the filter element 1 is installed in a machine, an indication or display device 29 is provided for indicating or displaying whether the switch element 22 is in the closed position or in the twisted position.

Fig. 1 shows how, in this example, an indication or display device 29 is made, i.e. in the form of a notch 30 in the aforementioned pin 28 and two symbols 31 or signs on the cover 3, i.e. indications "BP" and "F", respectively indicating "bypass" for the closed position and "filter" for the twisted position.

In this example, a blocking device 32 is provided for blocking the cover 10 relative to the switching element 22 so that the cover 10 rotates together with the switching element 22.

This would be the following way, namely: the same is true of the cover 10 when the switch element 22 is in the closed position. When the switch element 22 is rotated into its twisted position by means of the aforementioned pin 28, the cover 10 will automatically rotate into its twisted position, whereby the inlet 18 of the inlet duct 17 of the cover 10 is connected to the inlet 6 of the lid 3.

The blocking means 32 may be implemented in different ways.

For example, the cap 10 and the switch element 22 may be provided with corresponding features (e.g., grooves and fins), or a snap-fit connection may be formed therebetween.

One requirement for the blocking device 32 is that: the blocking means must be detachable or the cover 10 must be detachable or removable from the switch element 22.

Finally, in the closed position, a non-removable seal 33 is provided between the inlet port 23 or the outlet port 24 of the switching element 22 and the inlet 6 or the outlet 7 of the cover 3, respectively.

The seals 33 at the inlet port 23 and the outlet port 24 will prevent fluid leakage at the connection points where the inlet port 23 is connected to the inlet 6 of the lid 3 and the outlet port 24 is connected to the outlet 7 of the lid 3.

By providing a non-removable seal, the seal 33 may be prevented from loosening or moving when the lid 3 is mounted on the can 4. This provides additional security against poor sealing.

The seal 33, which is preferably made of a thermoplastic elastomer, is preferably cast in a groove provided for it on the inlet port 23 or the outlet port 24.

Thus, the respective seal 33 is part of the switching element 22.

However, it is not excluded: the side of the inlet 6 and outlet 7 of the lid 3 closest to the inlet port 23 and outlet port 24, respectively, of the switching element 22 in the closed position may be provided with a non-removable seal 33 instead of being provided on the inlet port 23 and outlet port 24, respectively, of the switching element 22.

In order to protect the seal 33 from damage, the inlet 6 and/or the outlet 7 of the lid 3 may be provided with a fillet or chamfer on the side closest to the inlet port 23 or the outlet port 24, respectively, of the switching element 22 in the closed position. For example, the chamfer may be formed as a straight chamfer of the edge between the inlet 6 and outlet 7, respectively, and the side of the cover 3 closest to the inlet 6 and outlet 7, respectively, in the closed position, the straight chamfer making an angle between 5 ° and 45 ° with the side of the cover 3 closest to the inlet 6 and outlet 7, respectively.

In addition, the cover 3 may have a recess on at least one of the two opposite sides of the cover closest to the inlet port 23 and the outlet port 24 of the switching element 22 in the twisted position, so that the seal 33 on the switching element 22 is not pressed when the filter device 1 is not in the closed position. This ensures that deformation of the seal 33 due to pressure loading over time is limited, thereby enhancing the service life and reliable operation of the seal 33.

The above-mentioned recesses are progressive recesses in a direction coinciding with the tangential direction in which the switching element 22 is rotatable, so that the seal 33 is pressed in a progressive manner when the filter device 1 is rotated into the closed position. In this way, the risk of damaging the seal 33 when the switching element 22 is rotated from the closed position to the twisted position (and vice versa) is reduced.

The operation of the filter device 1 is very simple, as follows.

During normal operation of the filter device 1, the switch element 22 and the top cover 10 will be in the twisted position described above.

This will allow a flow of gas to be cleaned to enter the filter device 1 through the inlet 6 in the cover 3 and then from the top cover 10 into the filter cartridge 12 through the inlet 18 and the inlet duct 17.

The outlet 19 of the inlet duct 17 is connected to the interior 20 of the filter element 12 so that the gas to be cleaned will flow through the filter element 12 from the inside to the outside, thereby removing impurities from the gas when passing through.

The cleaned gas then enters the region 34 between the filter cartridge 12 and the canister 4, from where it enters the space 21 between the top cover 10 and the lid 3.

The cleaned gas may then leave the filter device 1 through the outlet 7 in the cover 3.

When the cartridge 12 becomes saturated with contaminants, the cartridge 12 must be replaced.

In order to remove the filter device 1 in a correct and safe manner, the switch element 22 is rotated by the pin 28 into the closed position.

This means that, if the switching element 22 is a bypass element, the inlet 6 of the cover 3 and the outlet 7 of the cover 3 are connected to each other via a bypass conduit 25.

At this point, the gas to be cleaned will not pass through the filter element 9, but will flow through the bypass duct 25.

After the pressure in the filter housing 2 is released, the can 4 can then be unscrewed from the lid 3. In this way, the canister 4 with the filter element 9 can be removed.

In order to achieve this, the blocking means 32 must be removable, i.e. the cover 10 must be able to be separated from the switching element 22.

The filter element 9 can be removed from the tank 4 and a new filter element 9 can be placed in the tank 4.

The can 4 with the new filter element 9 can then be screwed back onto the lid 3.

In this case, the blocking means 32 will re-act or interfere with each other such that the cover 10 cannot rotate relative to the switching element 22.

Finally, the switching element 22 is rotated into the twisted position by means of the pin 28.

This will also cause the top cover 10 to rotate therewith, so that the inlet 6 of the lid 3 will be reconnected to the inlet 18 of the inlet duct 17.

In this way, the normal filtering operation of the filtering apparatus 1 is resumed.

During replacement of the saturated filter element 9, the switch element 22 will be rotated to the closed position and, if the switch element 22 is a bypass element, the gas to be cleaned will temporarily flow through the bypass duct 25. If filter material 26 is installed in the bypass duct 25 of such a bypass element, the gas to be cleaned will be at least partly cleaned of contaminants so that the downstream system is not adversely affected by the raw gas.

The invention is not limited to the embodiments described as examples and shown in the drawings, but a filter device according to the invention can be realized in all shapes and sizes without going beyond the scope of the invention.