FILTER UNIT WITH A RIGID FILTER AND A FLEXIBLE COVERING AND METHOD FOR MANUFACTURING SUCH A FILTER

Description

[0001] The invention relates to a filter unit which is capable of filtering out at least one gas and / or particles from a gas mixture, in particular from breathing air, as well as two methods for producing such a filter unit.

[0002] In one application, such a filter unit is a replaceable component of a respiratory mask. This respiratory mask comprises the actual mask, which a person wears in front of their face, a holder for the mask, for example a headband, and at least one filter unit, preferably two filter units. Typically, a filter unit can be screwed into and unscrewed from a screw thread or bayonet connection of the mask and thus replaced. The or each filter unit filters at least one gas, particle and / or coarse dust from the inhaled air and thereby protects the lungs and respiratory tract of the person wearing the respiratory mask. Such a respiratory mask is described, for example, in WO 2019 / 233 708 A1.

[0003] The filter unit comprises at least one filter that captures a gas and / or the particles. A filter in the form of a monolith made of activated carbon is known, capable of filtering out at least one gas from a gas mixture. Several parallel channels run through the filter. Such a filter is described in DE 10 2015 012 410 A1.

[0004] A filter unit with a relatively rigid filter is also described in DE 100 21 582 B4, DE 102 20 672 B4 and DE 103 04 216 B3.

[0005] The invention is based on the object of providing a filter unit for filtering out at least one gas and / or particles from a gas mixture, in particular from breathing air, wherein the filter unit can be used with greater operational reliability than known filter units. Furthermore, the invention is based on the object of providing a method for producing such a filter unit.

[0006] The object is achieved by a filter unit having the features of claim 1 and by a method having the features of claim 13. Advantageous embodiments are specified in the subclaims. Advantageous embodiments of the filter unit according to the invention are, where appropriate, also advantageous embodiments of a method according to the invention, and vice versa.

[0007] In the following, a person who uses a filter unit according to the invention to filter the inhaled air is referred to as "the wearer" of the filter unit.

[0008] The filter unit according to the invention is designed to filter at least one gas and / or particles from a gas mixture, optionally several different gases, while this gas mixture flows through the filter unit. The gas mixture can be homogeneous or heterogeneous and is, in particular, breathing air, which may contain harmful gases and solid particles.

[0009] The filter unit according to the invention comprises a filter, a casing made of an elastically deformable material and a cover made of a rigid material.

[0010] The filter unit provides an inflow side and an outflow side. When a gas mixture, from which at least one gas and / or particle is to be filtered out, flows through the filter unit, this gas mixture flows from the inflow side through the filter unit and through the filter to the outflow side. The inflow side has an inflow opening, and the outflow side has an outflow opening. The gas mixture flows into the filter unit through the inflow opening, flows through the filter, with the filter filtering out the gas or at least one gas or particle from the gas mixture, and leaves the filter unit in a filtered state through the outflow opening.

[0011] The filter is designed as a rigid body, extends along a central axis, and has a lateral surface. The lateral surface surrounds the central axis at a radial distance. The filter is preferably shaped like a cylinder, a truncated cone, a column, or a truncated pyramid with an n-sided cross-sectional area, n >= 3. Other geometric shapes are also possible.

[0012] The filter is designed to filter out at least one gas and / or particles from the gas mixture flowing through the filter, optionally several gases.

[0013] The casing of the filter unit surrounds the outer surface of the filter, preferably the entire outer surface. The casing preferably rests against the outer surface. The casing is made of a deformable and thus flexible material, in particular of a plastic and / or elastic material. As a result, the casing is capable of absorbing kinetic energy acting on the outer surface from the outside, particularly caused by an impact. The casing is preferably capable of reversible deformation when kinetic energy acts from the outside. The casing surrounds the inlet-side opening.

[0014] The cover is adjacent to the casing at the end facing the downstream side. The cover surrounds the downstream opening.

[0015] According to the invention, the outflow-side opening is recessed into the rigid cover. This feature enables a coupling unit to be connected to the cover. In particular, a screw thread or a bayonet connection, and / or the cover, can be designed to encompass and provide the coupling unit. Using this coupling unit, the filter unit can be connected, preferably detachably, to a mask or other device supporting the filter unit. The filter unit is held at a specific location on the device. Mechanical stability is increased because the cover is made of a rigid material.

[0016] According to the invention, the filter is designed as a rigid body. In many cases, a filter designed as a rigid body offers relatively low resistance to the breathing of a person using the filter unit, in particular lower resistance than a differently constructed filter with similar filtering performance. In particular, a rigid body made of activated carbon can be used as the filter—more generally, a rigid body made of a material comprising activated carbon. Because such a filter in the form of a rigid body offers relatively low resistance to breathing, the respiratory muscles of the wearer of the filter unit are less strained and only fatigue after a longer period of time compared to other possible filters with similar filtering performance. Furthermore, such a rigid filter is in some cases lighter than a differently designed filter with similar filtering performance.

[0017] Particularly due to the lower breathing resistance, the filter unit according to the invention allows the wearer to stay longer in a room whose air is contaminated with at least one harmful gas and / or particles and / or requires fewer filter unit changes. Nevertheless, the rigid filter according to the invention is actually capable of achieving the required airflow rate.

[0018] In many cases, a filter designed as a rigid body is easier to manufacture and / or handle than filtration using bulk material.

[0019] In one embodiment, the rigid filter is designed as a single rigid body. In another embodiment, the rigid filter consists of a sequence of individual rigid bodies. The sequence design allows the individual bodies to have at least two different properties overall, allowing the rigid filter to filter different gases from a gas mixture or to use different filtering methods. Both of these increase reliability in many cases.

[0020] A common disadvantage of a rigid filter is that it can break relatively easily when exposed to mechanical force. This mechanical force occurs, for example, when the filter unit falls to the ground or collides with a rigid object during use or transport.

[0021] The risk of mechanical damage to the filter of the filter unit according to the invention is reduced, on the one hand, by the casing, which, according to the invention, surrounds the casing surface and the inflow-side opening of the filter and is made of a reversibly deformable material. Due to its deformability, the casing is capable of absorbing kinetic energy to a certain degree and, in one embodiment, transferring it to the rigid cover and thus to a coupling point. On the other hand, the risk of damage is reduced by the fact that, according to the invention, the outflow-side opening is surrounded by a cover made of a rigid material.

[0022] The flexible casing around the filter's outer surface protects the filter in many cases, preventing a portion of the filter from breaking off or the filter from breaking, especially if the filter unit falls to the ground. In conjunction with the cover, the casing protects the filter from chemical environmental influences, especially water and water vapor, and to a certain extent also from thermal environmental influences, both from direct flame exposure and from extreme heat, especially when the filter unit is used in a smoky or fuming environment.

[0023] The filter is preferably made of a material comprising activated carbon. A plurality of parallel channels is preferably arranged through the filter. These channels connect the inflow side to the outflow side. A gas mixture flows through these channels, and at least one gas and / or particles are filtered out. The filter can be impregnated.

[0024] According to the invention, the filter extends along a central axis. The lateral surface surrounds this central axis. Every cross-section through the filter perpendicular to the central axis has the shape of a circle, an ellipse, or an n-gon with n greater than or equal to 3. It is possible for the filter to always have the same cross-sectional area along the central axis, or for it to have a cross-sectional area that increases in a direction from the inflow side to the outflow side.

[0025] According to the invention, the sheath is capable of absorbing kinetic energy and is made of an elastic material. Preferably, the sheath has a resilient effect and therefore deforms reversibly when a mechanical impulse acts on the sheath from the outside. Kinetic energy is absorbed when the resiliently designed sheath is compressed against the spring force. Preferably, the sheath expands again due to the spring force and, particularly preferably, returns to its original shape when the mechanical impulse is no longer applied.

[0026] In one design, the hardness of the casing remains constant in one direction from the casing surface to the central axis. In another design, the hardness of the casing decreases toward the central axis of the filter. Or the elasticity of the casing increases toward the central axis of the filter. In many cases, this design leads to even better mechanical protection of the rigid filter.

[0027] The casing preferably has a thickness of at least 0.1 cm, more preferably at least 0.5 cm, and in particular at least 1 cm. Thickness refers to the smallest dimension of the casing in a direction perpendicular to the central axis of the filter. In many cases, such a thick casing can better protect the rigid filter from mechanical damage than a thinner casing.

[0028] It is possible that the thickness of the casing may vary across its extension, particularly because the rigid filter deviates from an ideal geometric shape, for example, it is not an ideal cylinder. In this case, the thickness, which is preferably greater than or equal to 0.1 cm, is understood to be the minimum dimension of the casing in a direction perpendicular to the central axis of the filter.

[0029] According to the invention, the filter, designed as a rigid body, extends along a central axis and comprises a lateral surface surrounding the central axis. This lateral surface preferably extends from an inflow-side end face to an outflow-side end face. The gas mixture flows from the inflow-side end face to the outflow-side end face. Each end face can be perpendicular or oblique to the central axis. The two end faces can be arranged parallel or oblique to each other.

[0030] In one embodiment, the casing surrounds and covers only the outer surface of the filter, leaving both end faces exposed. Preferably, the casing extends along the entire length of the outer surface. In another embodiment, the casing covers not only the outer surface but also a region of the upstream end face of the filter. The casing leaves the upstream opening exposed and surrounds this upstream opening like a collar. In many cases, this embodiment results in a better connection between the casing and the rigid filter, or between the casing and an optional additional particulate filter arranged in front of the upstream end face of the rigid filter. In many cases, this embodiment provides even better support for the edge between the outer surface and the upstream end face of the filter.

[0031] In a further development of the two designs described above, the casing projects beyond the upstream end face. The dimension of the casing in a direction parallel to the central axis is thus larger than the dimension of the filter's surface area. Because the casing projects beyond, the risk of damage to the rigid filter with the casing is further reduced. The projecting casing can, to a certain extent, absorb kinetic energy due to a mechanical impulse, even if this mechanical impulse is directed at the upstream end face. Such an impulse can occur, for example, if the filter unit falls to the ground with the upstream end face facing downwards.

[0032] According to the invention, the filter unit comprises a rigid cover and a flexible casing. In one embodiment, the cover is mechanically connected to the casing. For example, a material connection, in particular an adhesive connection, connects the cover to the casing.

[0033] In another embodiment, the filter unit additionally comprises a rigid housing. The flexible casing is located between the outer surface of the rigid filter and the rigid housing. Preferably, the casing fills the entire area between the filter and the rigid housing, particularly preferably along the entire outer surface of the filter. The rigid cover is mechanically connected to the rigid housing. In this embodiment, the rigid housing can absorb mechanical impulses that impinge on the filter unit parallel or obliquely to the central axis of the filter and transmit them to the cover. In many cases, the rigid housing also protects the casing from external mechanical and chemical influences. Preferably, the thickness of the rigid housing is less than the thickness of the flexible casing. Just like the casing, the rigid housing can protrude beyond the inflow side.Preferably, the rigid housing surrounds the entire surface of the casing.

[0034] In In one embodiment, the filter unit additionally comprises a film. This film surrounds the outer side of the casing facing away from the filter. In one embodiment, the film is applied directly to the casing; in another embodiment, it is applied externally to the optional rigid housing. The film preferably surrounds the entire casing or at least that part of the casing that surrounds the outer surface of the filter, or the entire housing. The casing and the optional rigid housing are thus located between the filter and the film. The thickness of the film is preferably less than the thickness of the casing and also less than the thickness of the optional rigid housing.

[0035] The film can be designed to be water-repellent and / or to repel other chemicals that could be harmful to the filter. The film can be made from a flame-retardant material, thereby reducing the risk of the rest of the filter unit catching fire; in other words, the film can act as a flame retardant. A marking can be applied to the film, for example, a marking that distinguishes a specific filter unit from all other filter units in a group of filter units, or a marking that specifies the conditions for the application of the filter unit, e.g., a maximum service life, maximum ambient temperature, or maximum ambient humidity. The film can reflect light and / or fluoresce, allowing it to glow even in dark environments.This makes it easier for the wearer to find the filter unit to screw it on, and also for the wearer to find the filter unit. The film can also absorb light and other electromagnetic waves, thereby preventing the wearer from being seen.

[0036] Instead of a film, a layer of paint or varnish can be applied, which achieves a corresponding effect.

[0037] The gas mixture, for example, the breathing air, flows through the filter unit from the inflow side to the outflow side. In one embodiment, the gas mixture first flows through a particle filter, preferably made of paper, and then reaches the rigid filter. The rigid filter is thus arranged between the paper filter and the cover. The particle filter filters particles out of the gas mixture so that these particles cannot reach the rigid filter. The particle filter preferably covers the entire inflow side of the filter so that particles cannot bypass the particle filter and then reach the rigid filter.

[0038] The design with the particle filter in addition to the rigid filter reduces the risk of particle filters reaching the user, reduces the risk of particles in the gas mixture reaching the wearer, which could pose a health risk, and eliminates the need for the rigid filter to filter out particles from the gas mixture. The design in which the particle filter is positioned upstream of the rigid filter reduces the risk of particles settling in the rigid filter.

[0039] In one embodiment, the filter unit additionally comprises a handle guard. This handle guard is attached in front of the inlet opening and is connected to the casing or to the optional rigid housing, preferably by a materially bonded connection. The rigid filter is therefore located between the handle guard and the rigid cover. The handle guard prevents a user from reaching into the filter unit through the inlet opening and touching the inlet face of the filter, which can happen unintentionally, for example, when putting on or removing the filter unit. In addition, the handle guard reduces the risk of damage to the filter if the filter unit strikes an object in such a way that the object hits the inlet face of the filter. The handle guard thus prevents the filter from being mechanically damaged by reaching through the inlet opening.The handle guard preferably comprises a grid through which the gas mixture to be purified can flow. A gap preferably exists between the handle guard and the inflow-side face of the rigid filter.

[0040] The optional particulate filter is located between the handle guard and the rigid filter. In one embodiment, the particulate filter is applied to the inside of the handle guard and / or is held by the handle guard in a desired position relative to the rigid filter.

[0041] The design with the grip guard can be combined with a design in which the shroud protrudes beyond the upstream face of the filter. When the grip guard is connected to the protruding shroud or to an optional housing that also protrudes, a gap is created between the grip guard and the rigid filter. This design further reduces the risk of damage to the rigid filter.

[0042] In one embodiment, the filter unit additionally comprises a coupling unit, in particular an internal thread or an external thread or a bayonet connection. This coupling unit allows the filter unit to be connected, preferably detachably, to another device, in particular to a face mask or other mask or to a delivery unit for the gas mixture. The coupling unit is part of the rigid cover or is firmly connected to the cover and is preferably also rigid. The outflow-side opening preferably extends through the cover and the coupling unit.

[0043] According to the invention, the cover and the optional coupling unit are made of a rigid material. The cover supports the casing made of the deformable material. This design increases the mechanical stability of the filter unit. The cover and the coupling unit can form a single component or be two components that are firmly connected to each other.

[0044] According to the invention, the casing is integrally connected to the rigid filter. This design reduces the risk of the rigid filter moving undesirably relative to the casing. It is possible for the casing to also be integrally connected to the rigid housing. A relative movement of the filter could also lead to an undesirable movement of the filter relative to the rigid cover or the rigid housing and damage the filter. The integral connection is established on the casing surface, specifically on the entire casing surface or at least on a region of the casing surface. It is also possible for the casing to be stretched by the filter, therefore tending to contract, and thereby holding the filter.

[0045] The invention further relates to a method for producing a filter unit according to the invention.

[0046] According to the manufacturing method according to the invention, a molding body is used that provides a cavity. A circumferential inner wall of the molding body defines and delimits the cavity.

[0047] The manufacturing process with the forming body includes the following steps: A filter is provided. This filter is designed as a rigid body and is made in particular from a material that includes activated carbon. The filter extends along a central axis and has a lateral surface and two end faces. The filter is capable of filtering out at least one gas and / or particles from a gas mixture that flows through the filter. In addition, a cover made of a rigid material is provided. The rigid filter is placed in the cavity provided by the shaping body. The shaping body and the filter are designed and the filter is placed in the cavity in such a way that the cavity can accommodate the entire filter and a circumferential gap occurs between the lateral surface of the filter and the circumferential inner wall of the shaping body. InA flowable material is introduced into this gap between the outer surface and the shaping body. For example, a bulk material is poured into the gap, or a liquid or viscous material flows into the gap. Once introduced, the flowable material in the gap surrounds the outer surface of the filter, completely or at least partially. The flowable material in the gap hardens, completely or at least partially. It is therefore possible that the flowable material will still be flowable to a certain extent even after partial hardening. It is possible that the flowable material will expand or contract during hardening. After hardening, the flowable material forms a casing made of a flexible material, in particular a plastic and / or elastic material. This casing surrounds the outer surface of the filter, preferably completely.It is possible for the casing to protrude beyond one end face of the filter. The casing leaves an opening free on each of the two end faces of the filter. These openings function as the inflow and outflow openings. Such an opening can expose the entire end face or just part of the end face. Preferably, the flowable material bonds firmly to the casing surface of the filter upon curing. It is also possible for the flowable material to contract during curing and thereby hold the filter in place. These designs can be combined with one another. Once the flowable material has fully or at least partially cured, a workpiece is created which comprises the rigid filter and the casing. The cover is mechanically connected to this workpiece. After mechanical connection, the outflow-side end face of the filter faces the cover.

[0048] The filter, the casing around the outer surface of the filter and the cover connected to the casing belong to the filter unit produced according to the invention.

[0049] This manufacturing process allows the filter, cover, and flowable material to be manufactured separately, even at different locations and using a customized manufacturing process. In many cases, this manufacturing process is easier than if a filter had to be manufactured from a rigid body first in the casing.

[0050] According to the invention, the flowable material bonds to a certain degree with the filter material during curing, so that the casing is firmly bonded to the filter at the casing surface, either completely or at least partially. The flowable material exerts only a relatively low mechanical impact on the filter in the molding body when the flowable material is introduced into the gap. Therefore, the risk of damage to the filter during filling with the flowable material is relatively low.

[0051] The flowable material, which is introduced into the cavity provided by the forming body, adapts to the dimensions and geometry of the filter and those of the forming body. It is not necessary to precisely adapt the forming body to the geometry and dimensions of the filter. Furthermore, it is not necessary to manufacture and provide a suitable casing in advance.

[0052] This manufacturing process makes it possible to produce or provide a relatively large quantity of flowable material in a single manufacturing process and to use this relatively large quantity to produce the casings for several filter units according to the invention. Because the flowable material at least partially hardens in the gap, a workpiece is created that comprises the rigid filter and the casing around the rigid filter.

[0053] In a further development of this embodiment, this workpiece is pushed out of the forming body after the flowable material in the gap has hardened. The forming body belongs to a manufacturing tool and can be used to successively produce several filter units according to the invention. After pushing out, the cover is mechanically connected to the casing. To connect the cover to the casing, the filter element is preferably gripped and held by gripping the casing from two opposite sides.

[0054] It is also possible for the workpiece to be pushed out of the forming body and into a rigid housing. The rigid cover is connected to this rigid housing.

[0055] In this refinement, the molding body is available again at an early stage to produce another filter unit according to the invention or to clean the molding body. The molding body does not hinder the process of mechanically connecting the rigid cover to the flexible casing or to the rigid housing.

[0056] In a further development of the embodiment, the cover is first connected to the casing made of the cured or curing flowable material while the filter is located in the molding body. This creates the filter unit in the molding body. The filter unit is then removed from the molding body. This development makes it possible to grip the filter unit at the cover, in particular at a coupling unit of the cover, and to remove the thus gripped filter unit from the molding body.

[0057] In one embodiment, the outer surface of the casing, which is created by the curing of the flowable material, forms the outer surface of the filter unit. The cover is mechanically connected to the casing. The molding body, into which the filter and then the flowable material are placed, belongs to a manufacturing tool. This manufacturing method is preferably used to successively produce several similar filter units according to the invention.

[0058] The rigid filters of these filter units according to the invention can differ from one another in terms of dimensions and / or geometry, yet the same manufacturing tool can still be used. Such differences between different examples of the rigid filter are generally unavoidable, particularly due to manufacturing tolerances. The molding body can be relatively easily adapted to specified requirements, in particular to a desired casing thickness.

[0059] In a further development of this embodiment, the manufacturing tool further comprises a state-change unit. This state-change unit externally changes the state of the flowable material in the molding body. For example, the state-change unit supplies steam to the flowable material, thereby causing it to harden. Preferably, the state-change unit does not exert any relevant mechanical influence on the filter.

[0060] In another embodiment of the manufacturing method according to the invention, a rigid housing is provided. This rigid housing is used as the molding body or forms part of the molding body. The gap occurs between the outer surface of the filter and the inner wall of the rigid housing. InThe flowable material is placed in this gap and cures there, at least partially. After curing, the casing is located between the outer surface of the filter and the inner wall of the rigid housing. The cover is mechanically connected to the rigid housing.

[0061] Preferably, several filter units according to the invention are produced successively using the manufacturing method according to the invention. Both the rigid filters and the rigid housings may differ from one another in terms of dimensions or geometry, particularly due to unavoidable manufacturing tolerances. As a result, the gap between the filter and the housing varies from filter unit to filter unit. The flowable material and the flexible casing produced from it adapt to the respective geometry of this gap.

[0062] Two embodiments of the molding body were described above: a molding body of a manufacturing tool and a rigid housing of the filter unit as the molding body. In both embodiments, it is possible to produce several filter units according to the invention in succession, using the same flowable material each time. It is also possible to produce several filter units in succession using different flowable materials in order to produce several filter units with different casings that meet different requirements.

[0063] Optionally, a film is applied, for example, glued, to the casing or the rigid housing. This film surrounds at least the outer surface of the casing or the rigid housing. In one embodiment, the film is applied after the flowable material has cured and forms the casing. Particularly preferably, the film is glued to the outside of the rigid housing. It is also possible to apply a layer of paint or varnish to the casing or the housing. It is also possible to apply the layer of paint or varnish to the outside of the housing before the rigid filter and subsequently the flowable material are introduced into the housing.

[0064] In another embodiment, the circumferential inner wall of the forming body is bonded to a film, the filter is placed in the cavity, and then the flowable material is filled into the gap. In this embodiment, the gap into which the flowable material is introduced is located between the filter and the film. In many cases, this design allows the hardening, flowable material to bond firmly to both the outer surface of the filter and the inner surface of the film. In many cases, this eliminates the need for an adhesive bond between the film and the casing.

[0065] The manufacturing method according to the invention shows a way to produce a filter unit with a filter in the form of a rigid body, whereby - compared to other possible manufacturing methods - the risk of the filter being damaged during production is reduced.

[0066] The process allows the filter to be manufactured separately from the other components of the filter unit, making it possible to produce a large number of filter units one after the other.

[0067] In the following, the invention is described using several exemplary embodiments. Figure 1 schematically shows a side view of a filter unit according to the invention in accordance with the granulate embodiment; Figure 2 schematically shows a cross-sectional view in the plane A - A of Figure 1the filter unit according to the granulate embodiment; Figure 3 schematically shows in a side view how a filter unit according to the granulate embodiment and with a rigid housing is manufactured; Figure 4 schematically shows in a side view how a filter unit according to the granulate embodiment and without a rigid housing is manufactured: granulate is filled in and hardens; Figure 5 continuation of the granulate embodiment of Figure 4 : The filter unit is pushed out of the pot; Figure 6 schematically shows a side view of a filter unit according to the invention according to the foam embodiment; Figure 7 schematically shows a side view of how a tube made of liquid plastic for the filter unit according to the foam embodiment is produced; Figure 8 schematically shows a cross-sectional view in the plane B - B of Figure 7 the die for the production of the hose from Figure 7; Figure 9 schematically in a side view, how a filter unit according to the foam embodiment is made from the hose of Figure 7 is manufactured.

[0068] In the exemplary embodiments described below, the invention is used for a respiratory mask. This respiratory mask allows a person, such as a member of the fire department or police, to be in a contaminated area while still breathing pollutant-free air. This person is referred to below as the "wearer" of the respiratory mask. Thanks to the respiratory mask, the wearer breathes filtered air.

[0069] The filter unit can also be used in a respiratory protection device. This respiratory protection device comprises a face mask, at least one filter unit according to the invention, and a gas delivery unit, for example, a pump. This delivery unit draws in ambient air, which flows through the filter unit or at least one filter unit according to the invention. The filter unit or at least one filter unit according to the invention filters the drawn-in breathing air, and the wearer then inhales this breathing air purified of pollutants.

[0070] The respiratory protection mask comprises the actual face mask, which fits snugly against the face, and at least one filter unit, preferably at least two filter units. The face mask is made of a deformable material to adapt to the shape of the wearer's head and fit fluid-tight against the head. It also includes a threaded socket for the or each filter unit, into which a filter unit can be screwed and unscrewed. Alternatively, the or each filter unit can be detachably connected using a bayonet connection. Thanks to the detachable connection, the wearer can replace a filter unit without having to remove the face mask.

[0071] In the following, two embodiments of a filter unit 100 according to the invention are described, which are referred to as "granulate embodiment" and "foam embodiment".

[0072] Figure 1shows schematically in a side view a filter unit 100 according to the granulate embodiment, Figure 2 schematically a cross-sectional view in the plane A - A of Figure 1 . Figure 3 illustrates schematically in a side view how a filter unit 100 according to the granulate embodiment with a rigid housing is manufactured. Figure 4 and Figure 5 schematically illustrate in a side view the production of a filter unit 100 according to the granulate embodiment without a rigid housing. Figure 6 shows schematically in a side view a filter unit 100 according to the foam embodiment. Figure 7 illustrates schematically in a side view how a hose is produced from foam, which is subsequently used for the production of a filter unit 100 according to the foam embodiment. Figure 8shows schematically in a cross-sectional view in the plane B - B of Figure 7 which are used to manufacture the filter unit 100 according to Figure 7 used matrix. Figure 9 shows a schematic side view of how a filter unit 100 according to the foam embodiment is manufactured from a foam tube. The figures are not necessarily to scale.

[0073] According to both embodiments, a filter unit 100 has the shape of a cylinder with a truncated cone attached to the cylinder, which carries a thread 5. The filter unit 100 comprises an inflow side, which Figure 1 , and Figure 3 until Figure 6 shown below and through which the inhaled or sucked-in breathing air flows into the filter unit 100, and an outflow side through which the breathing air flows out of the filter unit 100 and which is shown above. The thread 5 is arranged on the outflow side. In Figure 1 and Figure 6 the direction in which air flows through the filter unit 100 is represented by an arrow L pointing from bottom to top.

[0074] The inhaled or sucked-in air flows through an inflow opening Ö.e on the inflow side into the filter unit 100, flows through the actual filter 1, and exits the filter unit 100 again on the outflow side through an outflow opening Ö.a. The filter 1 filters at least one gas from the breathing air while this breathing air flows through the filter 1. The filter 1 of the exemplary embodiment is not capable of filtering particles from the breathing air.

[0075] In both exemplary embodiments, the filter unit 100 comprises a filter 1 which is produced using pressed activated carbon and can be referred to as an activated carbon honeycomb monolith. The filter 1 can also be produced, for example, from Ca(OH) 2. The filter 1 is preferably impregnated with a suitable agent. The filter 1 is traversed by a plurality of parallel channels which extend parallel to the direction L and are preferably not connected to one another. This filter 1 can be constructed as described in DE 10 2015 012 410 A1 and in particular have one of the material compositions described therein. The filter unit 100 is constructed such that the breathing air which flows through the filter unit 100 also flows through the filter 1 and does not bypass the filter 1.

[0076] In one embodiment shown in the figures, the filter 1 is a single rigid body in the shape of a cylinder. It is also possible for the filter 1 to consist of several discs arranged one behind the other in a sequence. This design makes it easier to manufacture the filter 1 from different materials, allowing it to filter out different gases.

[0077] A monolithic filter 1 made of activated carbon in the form of a rigid body or a sequence of rigid bodies exerts significantly lower flow resistance and thus breathing resistance than another filter with similar filtering performance. Therefore, using such a monolithic filter 1 places less strain on the wearer than another filter. In some cases, such a filter is lighter (less heavy) than another filter with similar filtering performance. In some cases, a monolithic filter takes up less space than another filter with similar filtering performance.

[0078] In the exemplary embodiment, the rigid filter 1 has the shape of a cylinder extending along a central axis MA and having a lateral surface M, a circular inflow-side end face Sf.e and a circular outflow-side end face Sf.a. The central axis MA and the lateral surface M are perpendicular to the plane of the drawing of Figure 2. The inflow side forms the inflow end face Sf.e of the cylinder, and the outflow side forms the outflow end face Sf.a. The surface area M extends between these two end faces Sf.e, Sf.e. The rigid filter 1 can also have the shape of a truncated cone, with the diameter increasing from the inflow end face Sf.e to the outflow end face Sf.a.

[0079] A disadvantage of a filter designed as a rigid body made of activated carbon is the following: In the event of an impact, a part of the filter 1 may break off or the filter 1 may even break. Such an impact occurs, for example, when the filter unit 100 falls to a floor or collides with a hard object during use, for example, when the wearer turns their head.

[0080] In both embodiments, the filter unit 100 comprises several components that reduce the risk of damage to the filter 1 in the event of an impact, but cannot completely eliminate this risk. These components are described below.

[0081] The filter unit 100 according to the granulate embodiment comprises - in addition to the filter 1 - the following components: the thread 5 on the outflow side, wherein the thread 5 is made of a rigid material, preferably of a metal or a rigid plastic, a cover 2 made of a rigid material, preferably of a metal or a rigid plastic, wherein the cover 2 has the shape of a truncated cone, a housing 7 made of a rigid material, wherein the housing 7 comprises a tube, a casing 3 made of an elastically deformable material in the form of hardened granules, a particle filter 8 in front of the inflow-side end face Sf.e of the filter 1, optionally a flame protection 4 in the form of a film or a layer of paint or varnish around the housing 7 and a handle protection 6 in front of the inflow-side opening Ö.e.

[0082] In the granulate embodiment shown, the sheath 3 consists of cured granules. Other elastic materials are also possible, for example, a thermoplastic elastomer, an epoxy resin or other synthetic or natural resin, a polyurethane, a butyl compound, a silicone, or even an elastic hot-melt adhesive. The sheath 3 can be fully cured. If the sheath 3 is surrounded by a rigid housing 7, it is also possible that the sheath 3 is not fully cured.

[0083] The casing 3 is located between the outer surface M of the rigid filter 1 and the tube of the rigid housing 7. Preferably, the casing 3 completely fills the space between the outer surface M of the filter 1 and the rigid housing 7.

[0084] During the manufacture of the filter unit 100, the casing 3 is preferably bonded to the outer surface M of the cylindrical filter 1. A manufacturing method is described further below. Preferably, no separate step is required to connect the casing 3 to the filter 1. In particular, no adhesive bond or snap-in connection is required. Furthermore, there is not necessarily a further layer, for example, a layer of nonwoven fabric, between the outer surface M of the filter 1 and the casing 3.

[0085] According to the invention, the casing 3 is elastic. As a result, the casing 3 provides a resilient effect, which further reduces the risk of damage to the filter 1. Figure 1 , Figure 5 and Figure 6 the thickness of the sheath 3 is exaggerated.

[0086] The casing 3 absorbs kinetic energy acting on the filter unit 100 from the outside and thus protects the filter 1, and in particular its outer surface M and the two transitions between the outer surface M and the two end faces Sf.e, Sf.a, from mechanical damage to a certain extent. In one embodiment, the casing 3 provides an integral wall, i.e., the hardness of the casing 3 decreases from the outside to the inside. This enables the casing 3 to absorb kinetic energy even better. The elasticity of the casing 3 is preferably greater on the inside, i.e., in an area adjacent to the filter 1, than on the outside.

[0087] In the exemplary embodiment, the thickness of the sheath 3, i.e. the minimum dimension perpendicular to the central axis MA, is between 0.5 mm and 1.5 mm.

[0088] The housing 7 has the shape of a cylinder, which is completely open on the outflow-side end face and releases the circular opening Ö.3 on the inflow-side end face. It is made of a metal or a rigid plastic and surrounds the casing 3. The cover 2 is connected to the housing 7 by a material fit or by a snap connection. In one embodiment, the cover 2 is additionally connected to the end face of the casing 3 facing the outflow side, preferably by an adhesive connection and optionally additionally or instead by a snap connection. The thread 5 is firmly connected to the cover 2. It is possible for a force impulse to act on the filter unit 100 parallel or obliquely to the central axis MA on the cover 2, specifically from the inflow-side opening Ö.e. This force impulse is introduced into the rigid housing 7.

[0089] The flame-retardant film 4 is wrapped around the outward-facing surface of the housing 7 and is integrally bonded to this surface, preferably by an adhesive bond. In some applications, the flame-retardant film 4 enables the filter unit 100 to withstand higher temperatures compared to a design without a flame-retardant film 4. In other applications, the heat resistance of the housing 7 and the casing 3 is sufficient, so that a flame-retardant film 4 is not required. In some applications, the flame-retardant film 4 may also be necessary so that the filter unit 100 can be used in an environment with high humidity or heavy rain, optionally in conjunction with a high temperature. A marking of the filter unit 100 can be applied to the flame-retardant film 4.For example, this marking distinguishes the filter unit 100 from all other filter units used in a specific area. This marking can be linked to information about the filter unit 100, which information can optionally be stored in a database, e.g., a maximum usage period. The flame-retardant film 4 can reflect or fluoresce light and other electromagnetic waves, or even absorb them.

[0090] In an alternative embodiment (not shown), the rigid housing 7 is omitted. The cover 2 is then firmly bonded to the casing 3. The flame-retardant film 4 is applied to the outward-facing surface of the casing 3.

[0091] The grip guard 6 prevents the wearer's finger or a larger object from touching the inflow-side end face Sf.e of the filter 1 through the inflow-side opening Ö.e, which could lead to damage or contamination of the filter 1. The grip guard 6 is preferably in the form of a grid and is made of plastic or metal, for example, by casting or injection molding. The gas mixture to be filtered can flow through the grip guard 6. In the exemplary embodiment, the grip guard 6 is attached to the inflow-side end face of the rigid housing 7.

[0092] In the exemplary embodiment, a particle filter 8 is located in front of the inflow-side end face Sf.e of the filter 1, as seen in the flow direction L. This particle filter 8 filters particles from the air flowing through it. This particle filter 8 is located between the handle guard 6 and the filter 1, is preferably made of paper, and is preferably in the form of a pleated filter or a ring filter. Microglass fibers and / or polymer fibers are optionally added to the paper of the particle filter 8, and small amounts of cellulose are optionally added.

[0093] In the granulate embodiment, the casing 3 extends beyond the inflow-side end face Sf.e of the filter 1. The grip guard 6 is firmly bonded to the edge of the rigid housing 7 facing the inflow side and additionally to the inflow-side end face of the casing 3. Therefore, a gap exists between the inflow-side end face Sf.e of the filter 1 and the grip guard 6. This gap further reduces the risk of damage.

[0094] The casing 3 can protrude beyond the inlet-side end face Sf.e even if no grip guard is present. In the figures, the distance over which the casing 3 protrudes is exaggerated. Preferably, the casing 3 protrudes by a few millimeters, particularly preferably by less than 1 mm.

[0095] In one embodiment, the inflow opening Ö.e occupies the entire inflow end face Sf.e on the inflow side of the filter unit 100. In another embodiment, which is Figure 1 As shown, the casing 3 not only completely encloses the casing surface M of the filter 1, but also the inflow-side opening Ö.e and rests in a ring-like manner on the end face Sf.e of the filter 1 facing the inflow-side opening Ö.e. As a result, the casing 3 protects the filter 1 to a certain degree from mechanical damage even if a mechanical impulse acting from the inflow side acts on the filter unit 100, in particular if the filter unit 100 falls to the ground with the handle guard 6 first. The handle guard 6 is connected to the casing 3 and is at a distance from the inflow-side end face Sf.e.

[0096] Figure 3 to Figure 5schematically illustrate two preferred embodiments of a method for producing a filter unit 100 according to the granulate embodiment. In both embodiments, a granulate 13 is used which has the form of a bulk material at room temperature and sufficiently low air humidity. This granulate 13 becomes liquid or viscous and expands when the granulate 13 is heated and, optionally, the air humidity is additionally increased. Upon subsequent cooling, the granulate 13 solidifies and preferably does not contract at all or at least does not return to the expansion before heating. This granulate 13 can also be referred to as a hardening particle foam. Examples of materials from which such a granulate 13 can be made are: expandable polypropylene (EPP), expandable polystyrene (Styrofoam, EPS), another semi-crystalline thermoplastic.

[0097] Instead of granules 13, an alternative material can also be produced that is flowable and hardens at least to a certain degree, for example, by cooling or by adding a hardener to the material before use. The alternative material is, for example, a foam or another material mentioned above.

[0098] In the example of Figure 3 A filter unit 100 is manufactured with a rigid housing 7 made of metal or a hard plastic. The housing 7 has the shape of a cylinder with a fully open first end face and a second end face into which a circular opening is recessed, which is surrounded by a circular ring of the housing 7.

[0099] The rigid filter 1, the rigid housing 7 and the cover 2 with the thread 5 are prepared. The housing 7 is placed on a base so that the second end face points downwards. A disc-shaped placeholder 15 is inserted into the circular opening. The placeholder 15 completely fills the opening in the second end face. The particulate filter 8 is placed on the placeholder 15. The rigid filter 1 is placed on the particulate filter 8 so that the inflow-side end face Sf.e faces the particulate filter 8 and thus the placeholder 15. A circumferential gap Sp occurs between the outer surface of the housing 7 and the outer surface M of the filter 1.

[0100] The flowable granules 13 are poured into this gap Sp from above or introduced in another way, for example, after being heated. The granules 13 flow downwards and fill the gap Sp, surrounding the spacer 15. The gap is preferably designed such that no or only a small amount of flowable granules 13 enters the channels of the filter 1 and clogs them. In some cases, it may be useful for the granules 13 to penetrate into the channels to a small extent in order to better bond the filter 1 to the granules 13. In many cases, the granules 13 bond to the rigid filter 1 to a certain extent.

[0101] The granulate 13 hardens, for example, by cooling or by a hardener in the granulate 13 undergoing a chemical change. The hardened granulate 13 forms the casing 3. As soon as the granulate 13 has hardened sufficiently, the spacer 15 is removed, forming the inflow-side opening Ö.e. A schematically shown cutting tool 26 cuts off the granulate 13 that protrudes upwards above the housing 7.

[0102] The cover 2 with the thread 5 is placed on the housing 7 from above and mechanically connected to the housing 7. Optionally, the flame retardant film 4 is glued to the outer surface of the housing 7. Now, a filter unit 100 according to Figure 1 and Figure 2 manufactured.

[0103] Figure 4 and Figure 5 schematically illustrate the manufacture of a filter unit 100 without a rigid housing 7. Figure 4shows the following components of a tool which is used to produce such a filter unit 100, preferably used to produce several similar filter units 100 according to the invention in succession: a shaping body (reusable master mold) 10 in the form of a cylindrical pot, in the outer surface of which a plurality of openings are recessed, a lid 11 for the shaping body 10, in which a plurality of openings are preferably also recessed, a disc-shaped projection 14 on the bottom of the pot-shaped body 10 and a plurality of nozzles 12.1, ..., 12.6 at the level of the openings in the outer surface of the body 10.

[0104] The inner wall of the cup-shaped body 10 defines and surrounds a cylindrical cavity. The diameter of this cavity is larger than the diameter of the cylindrical filter 1. Therefore, a circumferential gap Sp occurs between the outer surface M of the filter 1 in the body 10 and the inner wall of the outer surface of the body 10.

[0105] The manufacturing process according to Figure 4 and Figure 5 includes the following steps: The cup-shaped body 10 is or will be positioned so that it is open at the top. Optionally, a particulate filter 8 is placed on the bottom of the cup-shaped body 10 or on the projection 14. The filter 1 is manufactured or provided and inserted into the cup-shaped body 10 such that the central axis MA of the filter 1 coincides with the central axis of the cup 10 and one end face of the cylindrical filter 1 rests on the projection 14 and the other end face points upwards. The projection 14 is smaller than the end face, so that the end face projects beyond the projection 14 on all sides. The end face that rests on the projection 14 becomes the inflow-side end face Sf.e, and the other end face becomes the outflow-side end face Sf.a. Optionally, the filter 1 is placed on the particulate filter 8 such that the inflow-side end face Sf.e touches the particulate filter 8.Granules 13, which as described above have the form of a bulk material at room temperature, are introduced into the gap Sp from above. Preferably, enough granules 13 are introduced that the entire gap Sp up to the upper edge of the body 10 is filled with granules 13. It is also possible for an upper area of ​​the gap Sp to remain free of granules 13. The cover 11 is placed on the shaping body 10 and preferably detachably connected to the body 10. The nozzles 12.1, ..., 12.6 eject hot steam or other hot steam, cf. . Figure 4This hot steam penetrates openings in the outer surface of the body 10 and in the lid 11 and reaches the granules 13 in the gap Sp. The granules 13 become liquid or viscous due to the steam and the heating. Optionally, the granules 13 expand during this process. The supply of heated steam is stopped. The granules 13 in the gap Sp harden. The hardening of the granules 13 in the gap Sp is limited on one side by the shaping body 10 and the lid 11 and on the other side by the filter 1. Therefore, the granules 13 harden under pressure. Optionally, the granules 13 contract during hardening. In one embodiment, the granulate 13 bonds to the filter 1 to a certain degree during curing. After curing, the cured and solidified granulate 13 forms the casing 3 around the casing surface M and around a part of the inflow-side end face Sf.e of the filter 1.The disc-shaped projection 14 causes the inflow-side opening Ö.e to be formed. Liquid granules 13 can penetrate into the channels in the filter 1 from below, but not from the side. The inflow-side opening Ö.e remains free of granules thanks to the projection 14. After the granules 13 have completely hardened, a deformable casing 3 is formed around the filter 1. In one embodiment, this casing 3 is integrally connected to the outer surface M of the filter 1. The cover 11 is removed again, and the casing-covered filter 1 is pushed out of the body 10 in the direction S, cf. Figure 5In one embodiment, the projection 14 belongs to a stamp which is extended and pushes the coated filter 1 out of the body 10 in the direction S. While the filter 1 is pushed out of the pot 10, granules 13 which have oozed out through the openings in the outer surface of the body 10 are cut off by means of a cutting tool 26 and thereby separated from the casing 3. Optionally, the lid 11 is displaced or pivoted in a direction perpendicular to the direction S such that granules 13 which have escaped through openings in the lid 11 are also cut off. A cylindrical coated filter 1 is now produced. Optionally, the flame-retardant film 4 is integrally bonded to the outer surface M of the coated filter 1, preferably by gluing.The cover 2 and the thread 5 are manufactured and connected to each other, which is preferably carried out separately from the manufacture and casing of the filter 1. The cover 2 is connected to the end face Sf.a of the casing 3 facing the exhalation side, preferably by a material connection, particularly preferably by gluing.

[0106] A filter unit 100 suitable for use is now manufactured.

[0107] In a modification of this method (not shown), the cover 2 comprising the thread 5 is connected to the upwardly facing end face of the casing 3 while the casing-covered filter 1 is still located in the shaping body 10.

[0108] In a further modification of the method, before the granulate 13 is poured in, not only the filter 1 but also the film 4 is placed into the pot 10. The film 4 is placed from the inside against the circumferential inner wall of the pot 10 so that ideally there is no gap between the film 4 and the inner wall. The granulate 13 is then placed in the gap Sp between the film 4 and the filter 1. After hot steam is supplied, the granulate 13 bonds firmly to both the filter 1 and the film 4. In one embodiment, the hot steam is introduced from above through the lid 11 and from below through openings in the base of the pot 10, while the outer surface of the pot 10 has no openings.

[0109] Figure 6 shows a filter unit 100 according to the foam embodiment. The same components have the same reference numerals as in the filter unit 100 according to the granulate embodiment ( Figure 1 and Figure 2 ).

[0110] The filter unit 100 according to the foam embodiment has, instead of a casing 3 made of a hardened granulate 13, a casing 9 in the form of a molded part made of a deformable material, in particular of at least one of the following materials, optionally of a mixture of several of the following materials: expanded thermoplastic foam, silicone elastomer, natural rubber elastomer (commonly called "rubber").

[0111] This casing 9, just like the casing 3, absorbs kinetic energy and surrounds the entire surface area M of the filter 1, but in this exemplary embodiment does not cover an end face Sf.e, Sf.a of the filter 1 and does not protrude beyond the inflow-side end face Sf.e of the filter 1. Therefore, the inflow-side opening Ö.e covers the entire end face Sf.e of the filter 1 facing the inflow side. A rigid housing 7 surrounds the surface area of ​​the casing 9 and the inflow-side opening Ö.e. The handle guard 6 is integrally connected to the housing 7 and covers the inflow-side opening Ö.e and therefore the entire end face Sf.e facing the inflow side. A particle filter 8 is located between the handle guard 6 and the inflow-side end face Sf.e of the filter 1.

[0112] In a preferred embodiment, the sheath 9 is made of an endless tube 19 made of one of the deformable materials mentioned above. Figure 7 and Figure 8 illustrate how this hose 19 is manufactured from liquid plastic 24. A preferred device for manufacturing the hose 19 comprises the following components: a die 21 with a round mandrel 25 and at least one web 23, an adhesive tool 22 and a feed tool not shown.

[0113] The matrix 21 extends in a plane perpendicular to the plane of the drawing of Figure 7 and in the drawing plane of Figure 8 lies. Figure 8 shows the matrix 21 in the plane B - B of Figure 5The die 21 has a circular recess. The web 23 or webs hold the round mandrel 25 in the center of this circular recess, so that the die 21 as a whole provides a recess in the shape of a circular ring (torus).

[0114] The feed tool presses liquid plastic 24 through this recess in the form of a circular ring. Preferably, this plastic 24 has previously been chemically and / or physically mixed with propellant gases. Figure 7 Arrows PR indicate the direction in which the feed tool presses the liquid plastic 24 through the die 21. This creates an endless tube, which hardens and, upon hardening, becomes the tube 19 made of the deformable material. The bonding tool 22 closes the slit or slits in this tube created by the web 23.

[0115] Figure 9schematically illustrates a possible embodiment of how the sheath 9 is manufactured using the endless tube 19. The preferred manufacturing method comprises the following steps: A schematically shown cutting tool with a cutting edge 20 cuts off a piece of the hose 19. The length of this piece of hose is preferably equal to the length of the filter 1, i.e. equal to the distance between the two end faces Sf.e, Sf.a of the filter 1. The cut-off piece of hose can also be longer than the filter 1. This piece of hose is pulled over the filter 1 in such a way that the inner wall of the piece of hose slides over the outer surface M of the releasably held filter 1. It is also possible for the filter 1 to be pushed into the piece of hose. In both cases, the piece of hose is moved in a feed direction VR relative to the filter 1. In both cases, the cut-off piece of hose forms the casing 9 after the relative movement. After the relative movement, the outer surface M of the filter 1 is completely surrounded by the casing 9.The cover 2 with the thread 5 is firmly connected to one end face of this casing 9, the handle protection 6 to the other end face.

[0116] In a modification, the hose 19 is first pulled over the filter 1 or the filter 1 is pushed into the hose 19, whereby the inner wall of the hose 19 slides over the outer surface M of the filter 1. Subsequently, the piece of the hose 19 that surrounds the outer surface M is cut off from the rest of the hose 19 by means of the cutting edge 20.

[0117] It is possible that the hose 19 or the cut-off hose section will be heated and expand. The filter 1 is pushed into the expanded hose 19 or the expanded cut-off hose section. The hose 19 or the cut-off piece will contract again and hold the filter 1 in place.

[0118] In a further modification, the workpiece comprising the rigid filter 1 and the cut-off hose section is pushed into a rigid housing 7, or the rigid housing 7 is pulled over this workpiece. Subsequently, the cover 2 is firmly connected to the rigid housing 7 with the thread 5. List of reference symbols

[0119] 1 Filter made of activated carbon (monolith), has the shape of a cylinder with a surface area M and two end faces Sf.e, Sf.a, is traversed by parallel channels 2 Cover of the filter unit 100, with the rigid housing 7 or the particle foam 3 or the hose piece 9 firmly connected 3 Casing in the form of hardened granulate 13, surrounds the surface M of the filter 1, can protrude beyond the inflow-side face Sf.e, produced from the granulate 13, surrounded by the rigid housing 7 4 optional flame retardant film, glued to the outside of the rigid housing 7 or to the casing 3, 9 5 Thread, firmly connected to the cover 2 6 Handle protection in front of the inlet opening Ö.e 7 rigid housing, has the shape of a cylinder, surrounds the casing 3, 9 8 Optional paper particle filter in front of the inlet face Sf.e, located between filter 1 and handle guard 6 9 Sheathing made of a deformable material, in particular of thermoplastic foam or elastomer, surrounds the outer surface M of the filter 1, is produced from the hose 19, wherein the cutting edge 20 cuts off a piece of the hose 9 10 shaping body (original form) in the shape of a pot, defines a cylindrical cavity to accommodate the filter 1 11 Lid for the shaping body 10 12.1, ... Nozzles which expel hot steam into the interior of the pot 10 13 Granules, which are filled into the rigid housing 7 or into the shaping body 10 and then surround the surface M of the filter 1, act as the flowable material 14 disc-shaped projection at the bottom of the shaping body 10, which creates the inflow opening Ö.e, pushes the coated filter 1 out of the body 10 15 disc-shaped placeholder for the inflow-side opening in the casing 3, arranged at the bottom of the housing 7 during production 19 endless tube made of thermoplastic foam from which the sheath 9 is cut off 20 Cutting edge which cuts the sheath 9 from the hose 19 21 Die through which liquid plastic 24 is pressed to produce the tube 19 comprises the mandrel 25 and the web 23 22 Adhesive tool that closes the hose 19 23 Web in the die 21, holds the mandrel 25 24 liquid plastic from which the hose 19 is made, optionally mixed with propellant gases 25 Mandrel in the die 21, held by the web 23 26 Cutting tool which cuts off granules 13 which protrude beyond the pot 10 after curing 100 Filter unit, comprises the filter 1, the cover 2, the thread 5 and the handle protection 6 as well as the casing 3 made of hardened granulate (granulate embodiment) or the casing 9 made of foam or rubber (foam embodiment) L Direction in which the inhaled breathing air flows through the filter unit 100 M Shell surface of the cylindrical filter 1, surrounded by the casing 3, 9 MA Central axis of the cylindrical filter 1 Ö.a outlet-side opening, arranged in cover 2 Ö.e inflow-side opening, protected by the handle guard 6 PR Direction in which the feed tool presses the liquid plastic 24 through the die 21 S Direction in which the stamp with the projection 13 pushes the coated filter 1 out of the forming body 10 Sf.a outflow-side face of the cylindrical filter 1, is perpendicular to the central axis MA Sf.e inflow-side face of the cylindrical filter 1, is perpendicular to the central axis MA Sp Gap between the inner wall of the rigid housing 7 or the outer surface M of the shaping body 10 and the outer surface M of the filter 1 in the housing 7 / body 10 is filled with granulate 13 VR Feed direction in which the hose 19 is moved relative to the filter 1 to produce the casing 9

Claims

1. Filter unit (100) comprising - a filter (1), - a casing (3, 9) made of an elastically deformable material and - a cover (2, 5) made of a rigid material, wherein the filter unit (100) comprises - an inflow side having an inflow-side opening (Ö.e) and - an outflow side having an outflow-side opening (Ö.a), wherein the outflow-side opening (Ö.a) is recessed in the cover (2, 5), wherein the filter unit (100) is designed such that a gas mixture can flow from the inflow side through the inflow-side opening (Ö.e), the filter (1) and the outflow opening (Ö.a) to the outflow side, wherein the cover (2, 5) adjoins the casing (3, 9) at the end of the casing (3, 9) facing the outflow side, wherein the filter (1) - is designed as a rigid body, - extends along a central axis (MA), - has a lateral surface (M) which surrounds the central axis (MA), and - is designed to filter out at least one gas and / or particles from a gas mixture flowing through the filter (1), in particular from breathing air, and wherein the casing (3, 9) - surrounds the lateral surface (M) of the filter (1), - is integrally bonded to the filter (1) on the lateral surface (M) of the filter (1) and - is designed to absorb kinetic energy acting on the lateral surface (M).

2. Filter unit (100) according to claim 1, characterized in that the casing (3, 9) has a resilient effect.

3. Filter unit (100) according to any of the preceding claims, characterized in that the hardness of the casing (3, 9) decreases in a direction towards the central axis (MA) of the filter (1) and / or the elasticity of the casing (3,9) increases in a direction towards the central axis (MA) of the filter (1).

4. Filter unit (100) according to any of the preceding claims, characterized in that the casing (3, 9) has a thickness of at least 0.1 cm, preferably of at least 0.5 cm, in particular of at least 1 cm, and preferably of at most 1.5 cm, particularly preferably of at most 0.5 cm.

5. Filter unit (100) according to any of the preceding claims, characterized in that the filter (1) designed as a rigid body has an inflow-side end face (Sf.e) and an outflow-side end face (Sf.a), wherein the casing (3, 9) - protrudes beyond the inflow-side end face (Sf.e) and - surrounds the inflow-side opening (Ö.e).

6. Filter unit (100) according to claim 5, characterized in that the casing (3, 9) covers a region of the inflow-side end face (Sf.e) of the filter (1).

7. Filter unit (100) according to any of the preceding claims, characterized in that the cover (2, 5) is connected to the casing (3, 9) at the end of the casing (3, 9) facing the outflow side.

8. Filter unit (100) according to any of the preceding claims, characterized in that the filter unit (100) comprises a rigid housing (7), wherein the casing (3, 9) is located between the lateral surface (M) of the filter (1) and the rigid housing (7) and wherein the cover (2, 5) is mechanically connected to the rigid housing (7), preferably at an end of the rigid housing (7) facing the outflow side.

9. Filter unit (100) according to any of the preceding claims, characterized in that the filter unit (100) comprises a film (4), wherein the film (4) surrounds the outer side of the casing (3, 9) facing away from the filter (1) or an outward-facing surface of the rigid housing (7).

10. Filter unit (100) according to any of the preceding claims, characterized in that the filter unit (100) comprises a grip guard (6) in front of the inflow-side opening (Ö.e), wherein the grip guard (6) is connected to the casing (3, 9) or to the rigid housing (7).

11. Use of a filter unit (100) according to any of the preceding claims as a component of a breathing apparatus, in particular a breathing mask, for filtering out at least one gas and / or particles from breathing air.

12. Breathing apparatus comprising at least one filter unit (100) according to any of claims 1 to 10.

13. Method for producing a filter unit (100), wherein the method is carried out using a shaping body (7, 10, 11), wherein the shaping body (7, 10, 11) provides a cavity and wherein the method comprises the steps whereby a filter (1) is provided, which - is designed as a rigid body, - extends along a central axis (MA), - has a lateral surface (M) which surrounds the central axis (MA), as well as an inflow-side end face (Sf.e) and an outflow-side end face (Sf.a) and - is designed to filter out at least one gas and / or particles from a gas mixture flowing through the filter (1), in particular from breathing air, a cover (2, 5) made of a rigid material is provided, the filter (1) is placed into the cavity provided by the shaping body (7, 10) in such a way that a gap (Sp) occurs between the lateral surface (M) of the filter (1) and a circumferential inner wall of the shaping body (7, 10, 11), wherein the cavity preferably surrounds the entire lateral surface (M), a flowable material (13), in particular a bulk material, is introduced into the gap (Sp) in such a way that the flowable material (13) in the gap (Sp) surrounds the lateral surface (M) of the filter (1), the flowable material (13) hardens in the gap (Sp) so that the flowable material (13) integrally bonds to the lateral surface (M) of the filter, the hardened material (13) forms a casing (3) made of a flexible material, which completely surrounds the lateral surface (M) of the filter (1) and leaves an opening (Ö.a, Ö.e) free on each of the two end faces (Sf.e, Sf.a) of the filter (1), the cover (2, 5) is mechanically connected to the workpiece created after hardening in such a way that the outflow-side end face (Sf.a) of the filter (1) faces the cover (2, 5), wherein the filter (1), the casing (3) around the lateral surface (M) of the filter (1) and the connected cover (2, 5) jointly belong to the produced filter unit (100).

14. Method according to claim 13, characterized in that a rigid housing (7) is provided, wherein the rigid housing (7) is used as the shaping body (7, 10, 11) or as a part of the shaping body (7, 10, 11), wherein the gap (Sp) into which the flowable material (13) is introduced occurs between the lateral surface (M) of the filter (1) and the inner wall of the rigid housing (7), wherein the casing (3), which is formed after the hardening of the flowable material (13), is located between the lateral surface (M) of the filter (1) and the inner wall of the rigid housing (7) and wherein the step of connecting the cover (2, 5) to the workpiece comprises the step of mechanically connecting the cover (2, 5) to the rigid housing (7).

15. Method according to claim 13, characterized in that after the flowable material (13) has hardened, the workpiece comprising the filter (1) and the casing (3) is pushed out of the shaping body (10, 11) and the step of connecting the cover (2, 5) to the workpiece comprises the step of connecting the cover (2, 5) to the casing (3), preferably by means of an integral bond