Method for manufacturing a filter unit for an air purification respirator and such a filter unit

Abstract

A method of manufacturing a filter unit (100) for an air purification respirator, the method comprising: providing a sheet (20) of filter material; supplying a portion of the filter material to an open mold (11, 12) of an injection molding machine; closing the mold (11, 12) to thereby cut out filter walls (112, 122) from the sheet (20); holding the filter walls within the mold (11, 12); forming filter panel frames (111, 121) around the filter walls (112, 122) by injection molding a polymer material onto the filter walls (112, 122); opening the mold (11, 12); and recovering filter panels (110, 120) comprising the filter walls (112, 122) and the filter panel frames (111, 121) secured to the filter walls. Also disclosed is a filter unit for an air purification respirator.

Description

Technical Field

[0001] The present disclosure generally relates to air-purifying respirators, and more specifically to a method for manufacturing filter units for such air-purifying respirators. Also disclosed is a filter unit for an air-purifying respirator.

Background Art

[0002] Air-purifying respirators are air filtration devices that protect against inhalation of both large and small particles by removing contaminants through filtration or absorption. They may be passive APRs or powered PAPRs. PAPRs have a greater advantage over APRs as they require only a simple fit test and do not increase breathing. Also, PAPRs provide positive pressure inside the face mask, reducing the risk of leakage into the mask caused by growth such as beards and wrinkles.

[0003] Air-purifying respirators typically include a mask for covering the wearer's nose and mouth (half of the face) or the entire face (the whole face), a valve element, and a filter unit for purifying the inhaled air by filtering the air entering from the ambient atmosphere with the mask.

[0004] Therefore, the filter unit constitutes an important component of the air-purifying respirator. Naturally, the filter unit should be able to remove dangerous or other undesirable particles from the inhaled air. Other desirable characteristics of the filter unit are that it should be easily replaceable, lightweight and small so as not to impede the wearer, environmentally friendly, and can be manufactured quickly at low cost.

[0005] One type of previously known filter unit includes a relatively thin sheet of filter media that is pleated to form an accordion-shaped filter insert that is inserted into and sealed to the inner wall of a filter housing having an air inlet and an air outlet. Another type of well-known filter unit includes a relatively thick felt-like filter material, one or several layers of which are inserted into the filter housing and sealed to the inner wall for attachment.

[0006] Patent Document 1 discloses a filter unit panel comprising a plurality of filter units and an outer frame surrounding these units. Each of the plurality of filter units includes a pleated filter medium and a frame body supporting the filter medium.

[0007] Patent Document 2 discloses a method for manufacturing an air filter unit, which includes disposing an air filter medium in a metal mold and forming a support frame at the peripheral portion of the air filter medium.

[0008] Patent Document 3 discloses an automatic filter net generation device comprising an automatic net supply device, an injection molding machine, and a waste recycling device.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0010] The object of the present invention is to provide an improved manufacturing method for a filter unit for an air purification respirator.

[0011] Another object is to provide such a method that enables the filter unit to be manufactured at high speed and low cost.

[0012] A further object is to provide such a method that enables modular manufacturing that can easily change the total filter area of the filter unit.

[0013] Yet another object is to provide a method that enables easy recycling of the filter unit after use.

[0014] Yet another object is to provide an improved filter unit for an air purification respirator.

[0015] In general, all terms used in the claims should be construed according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to elements, apparatuses, components, means, steps, etc. should be construed broadly as referring to at least one example of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein need not be performed in the exact order disclosed, unless explicitly recited.

[0016] According to a first aspect, the present disclosure provides a method of manufacturing a filter unit for an air purification respirator as defined in appended claim 1. The manufacturing method includes the following steps, namely, providing a sheet of filter material; feeding a portion of the filter material into an open mold of an injection molding machine; wherein the mold comprises two mold halves, and the two mold halves have a mold cavity and a corresponding mold shape for forming at least one filter panel, an inlet wall panel, and an outlet wall panel, step; closing the mold, thereby cutting a filter wall from the sheet; within the mold at least one holding the filter wall; In order to form a filter panel, within the mold, at least one forming a filter panel frame around the filter wall by injection molding a polymeric material onto the filter wall; at least one of the filter wall each opening the mold; simultaneously, by injection molding a polymer material into the mold, forming an inlet wall panel and an outlet wall panel as an integral part together with at least one filter panel, wherein the pair of panels are interconnected by respective bridge portions, step; recovering the filter panel, the filter panel having the filter wall and a filter panel frame fixed to the filter wall. the inlet wall panel and the outlet wall panel; folding a plurality of panels in a zigzag form at the bridge portions to form a stack of panels having at least one filter panel disposed between the inlet wall panel and the outlet wall panel, step. ​

[0017] Thus, the method enables a filter panel forming part of a filter unit to be readily manufactured in one operating station in an operation combining cutting of a filter material and injection molding of a filter panel frame. This reduces the need for intermediate handling and storage of components. The method also enables low cost and high manufacturing speed. The operating station preferably comprises a mold formed from at least two mold halves or members movable relative to each other for opening and closing the mold. At least one of the mold halves or members comprises a cutting tool arranged to cut a filter wall from a filter material sheet when the mold is closed.

[0018] In addition, the method also enables a modular manufacturing process and corresponding modular structure of the filter unit. This is because when forming the final filter unit, any number of identical filter panels achieved by the method can be stacked together. Thereby, the total filter area of the filter unit can be easily adapted to various requirements.

[0019] Furthermore, the entire filter unit having an inlet wall panel, an outlet wall panel, and any number of intermediate filter panels can be easily manufactured.

[0020] In some embodiments, the filter material and the injected polymeric material comprise the same polymeric material. This enables the filter frame to be joined to the filter wall by material fusion during injection molding. In addition, this facilitates reuse of the filter panel as the entire panel can be reused as a unit without the need to separate the filter wall from the filter panel frame.

[0021] The same polymeric material may be PP (polypropylene) or PA (polyamide resin).

[0022] Alternatively or in combination, the step of closing the mold to cut out the filter walls can include the step of cutting out a plurality of filter walls simultaneously, and the step of forming the filter panel can include the step of simultaneously forming a number of filter panels corresponding to the plurality of filter walls.

[0023] The inlet wall panel and the outlet wall panel can be manufactured by injection molding of a suitable material. Preferably, the inlet wall panel and the outlet wall panel contain the same material as the filter panel of the filter unit. By this means, the reuse of the entire filter unit is facilitated. Further, by using the same material, the panels can be sealed and joined to each other by material fusion for forming a sealed filter unit.

[0024] This method can include sealing and joining the peripheral edges of the filter panel, the inlet wall panel, and the outlet wall panel. Thereby, a filter unit including the inlet panel, the discharge port panel, and the intermediate filter panel can be directly connected to an air purification respirator without being received in or sealed and attached to any airtight housing or similar additional components in order to prevent the filtered air flow inside the filter unit from being mixed with the ambient air.

[0025] The peripheral edge may be sealed and joined by adhesion, heat fusion, ultrasonic welding, or by mechanical engagement means.

[0026] According to a second aspect, the present disclosure provides a filter unit for an air purification respirator as defined in claim 9. The filter unit comprises an inlet wall panel having an air inlet opening, an outlet wall panel having an air outlet opening, at least one a filter panel, each filter panel comprising filter frame; a filter wall and a ventilation passage at least one the filter panel, and the plurality of panels are formed as an integral part together with a pair of panels interconnected by respective bridge portions and bent at the bridge portions in a zigzag form, of the panelsealed Form a stack and A plurality of filter panels are disposed between an inlet wall panel and an outlet wall panel, and the stack defines an inner ventilation passage from an air inlet opening through a filter wall and a ventilation path to an air outlet opening, and this inner ventilation passage is sealed from the outside of the stack.

[0027] In an embodiment of the filter unit, the filter panel is planar.

[0028] Each filter panel may comprise a peripheral sealing portion that extends along the periphery of the panel and is arranged to make a sealing contact with a corresponding peripheral sealing portion of an adjacent panel.

[0029] Each filter panel comprises an inner sealing portion that extends around the air through the ventilation path and is arranged to make a sealing contact with a corresponding inner sealing portion of an adjacent filter panel.

[0030] Each filter panel may comprise a peripheral frame surrounding the filter wall.

[0031] The filter wall and the filter frame may comprise the same polymeric material.

[0032] The filter panel, the inlet wall panel and the outlet wall panel may comprise the same polymeric material.

[0033] Further objects and advantages of the method and the full face mask will be apparent from the following description of the embodiments and the appended claims.

Brief Description of the Drawings

[0034] Here, with reference to the accompanying drawings, embodiments and implementations will be described by way of example.

Figure 1

Figure 1b

Figure 2a - 2b

Figure 3a - 32b

[0035] Aspects of the present disclosure will now be described in more detail below with reference to the accompanying drawings, in which certain embodiments of the invention are shown.

[0036] However, these aspects may be embodied in many different forms and should not be construed as limiting. Rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the technology of all aspects of the invention to those skilled in the art. Like reference numerals refer to like elements throughout the description.

[0037] FIG. 1 schematically shows a manufacturing station and the steps of a manufacturing method according to an embodiment. The manufacturing station includes an injection molding machine 10, which has a first mold half 11 and a second mold half 12 that is movable to engage and disengage from the first mold half 11. The first mold half 11 has a mold cavity 11a, and the second mold half 12 has a corresponding geometric shape 12a for forming, together with the cavity 11a, a space that defines the shape of a filter panel (not shown in FIG. 1) to be manufactured. Further, the second mold half includes a cutting tool 13. In the illustrated example, the cutting tool 13 includes a knife. However, the cutting tool may comprise other means for cutting or severing the filter wall from a sheet 20 of filter material. Such other means can include punching means, thermal cutting means, and the like. The cutting tool may be disposed in either of the mold halves, or may include two or more cooperating tools disposed in both mold halves. The cutting tool 13 has a shape corresponding to the peripheral shape of the filter wall to be cut.

[0038] The supply roll 21 of the sheet-like filter material is arranged to supply the sheet 20 of the filter material between the first mold half 11 and the second mold half 12 when the mold is open. The free end of the filter material sheet 20 is received by the collection roll 22. The supply roll and the collection roll 22 are arranged to stretch or maintain tension on the sheet during the cutting operation. The filter material can include a variety of different materials having filtering properties. In the illustrated example, the sheet includes non-woven fibers of PP. However, other examples of suitable filter materials include PTFE (polytetrafluoroethylene) and PA (polyamide resin).

[0039] In the illustrated exemplary embodiment of the method of manufacturing the filter unit, the sheet 20 of the filter material is supplied between the first mold half 11 and the second mold half 12 when the mold is open. Then, the mold is closed, whereby the cutting tool 13 cuts off a portion of the filter material. The cut-out portion of the filter material is held in a predetermined position within the mold cavity 11a by the clamping action applied by the cooperating first mold half 11 and second mold half 12. Alternatively or in combination, the mold can comprise separate clamping means (not shown) for holding the cut-out portion of the filter material within the mold cavity 11b. While keeping the mold closed and holding the cut-out portion of the filter material within the mold cavity 11a, the polymeric material is injected into the mold cavity 11a through the passage 11b disposed within the first mold half 11. The polymeric material to be injected can be selected from a wide range of thermoformable polymers. Preferably, the injected material should be fusible with the filter material such that the material injected when forming the filter panel is firmly fixed to the filter material. The injected material can include, for example, the same polymeric material as the filter material. In the illustrated example, both the filter material and the injected material include PP. In an alternative example not shown, both the filter material and the injected material include PA.

[0040] The mold cavity 11a is formed such that when the injected material is cured, it forms a rigid frame around the cut portion of the filter material, and this frame is fixed to the filter material. When the injected material is cured, the mold is opened, and a filter panel including the filter wall and the filter frame fixed thereto is removed from the mold cavity 11a.

[0041] In an alternative example (not shown), the first mold half comprises a plurality of mold cavities, and the second mold half comprises a corresponding number of corresponding geometries and a corresponding number of cutting tools. In such an embodiment, a sheet of filter material is supplied between the mold halves so as to overlap all the mold cavities. Such an embodiment enables several filter panels to be manufactured in each injection cycle of the injection molding machine.

[0042] To complete the filter unit, the inlet wall panel and the outlet wall panel may be manufactured by injection molding in a separate injection molding machine. Alternatively, the inlet wall and / or the outlet wall panel may be injection molded in the same injection molding machine either with or simultaneously with the filter panel. The inlet wall panel and the outlet wall panel typically do not contain any filter material, so the mold cavities for forming these panels need not be covered by the filter material when the mold is closed.

[0043] In a further alternative example (not shown), a plurality of mold halves may comprise mold cavities, corresponding mold geometries, for forming one or more filter panels, an inlet wall panel, and an outlet wall panel, and these panels are formed as an integral part together with a pair of panels interconnected by respective bridge portions. The bridge portions may act as hinges, and the panels are folded in a zigzag configuration to form a stack of panels with one or several filter panels arranged between the inlet wall panel and the outlet wall panel.

[0044] After providing the filter panel, the inlet wall panel, and the outlet wall panel by any of the above methods, with one or more filter panels disposed between the inlet wall panel and the outlet wall panel, the plurality of panels are stacked vertically. Thereafter, the peripheral edges of the panels are sealingly joined to each other such that the interior of the filter unit, including the stack of panels, is sealed from the surrounding atmosphere. This can be achieved by mechanical engagement means that clamp the stacked panels together to make sealing contact. Alternatively or in combination, the edges of the panels may be joined to each other by adhesion, heat fusion, and / or ultrasonic welding.

[0045] Thereby, the filter unit is easily manufactured in a quick and cost - efficient manner. The resulting filter unit can be directly attached to the mask of an air - purifying respirator without the need for an additional filter housing.

[0046] Figures 2a and 2b show an exemplary filter unit 100 when assembled, in respective perspective views. Figures 3a and 3b show the filter unit 100 in respective perspective exploded views.

[0047] The filter unit 100 includes a first filter panel 110, a second filter panel 120, an inlet wall panel 130, and an outlet wall panel 140, which are stacked together with the filter panels 110, 120 disposed between the inlet wall panel 130 and the outlet wall panel 140.

[0048] Both filter panels 110, 120 are manufactured as described above and include filter panel frames 111, 121 and filter walls 112, 122 where the filter walls are made of a breathable filter material and are surrounded by the filter panel frames 111, 121. Each filter panel frame 111, 121 has two peripheral sealing portions 111a, 111b, 121a, 121b that face each other in opposite directions.

[0049] The inlet wall panel 130 and the outlet wall panel are generally impermeable to air, except for the inlet opening 135 and the outlet opening 145, respectively. Each of the inlet wall panel 130 and the outlet wall panel 140 includes peripheral sealing portions 131, 141 facing the adjacent filter panels 110, 120.

[0050] When stacked, the peripheral sealing portion 131 of the inlet wall panel makes sealing contact with the upper peripheral sealing portion 111a of the first filter panel 110. Correspondingly, the lower peripheral sealing portion 111b of the first filter panel 110 makes sealing contact with the upper peripheral sealing portion 121a of the second filter panel 120, and the lower peripheral sealing portion 121b of the second filter panel makes sealing contact with the peripheral sealing portion 141 of the outlet wall panel 140. By this means, the interior of the filter unit 100 is sealed from the surrounding atmosphere, except for the inlet opening 135 and the outlet opening 145.

[0051] Both filter panels 110, 120 further show first ventilation passages 113, 123 surrounded by first sealing rims 114, 124 that cooperate with each other. The first filter panel 110 disposed adjacent to the inlet wall panel 130 further shows a second ventilation passage 115 aligned with the inlet opening 135 disposed in the inlet wall panel 130. The second ventilation passage 115 and the inlet opening 135 are surrounded by respective second sealing rims 116, 136 that cooperate with each other.

[0052] In FIGS. 2a - 3b, the flow of unfiltered air is represented by solid arrows, and the flow of filtered air is represented by dashed arrows. When the filter panels 110, 120, the inlet wall panel 130, and the outlet wall panel 140 are stacked and sealed as described above, air from the surroundings enters the filter unit 100 through the inlet opening 135 of the inlet wall panel and continues through the second air passage 115 of the first filter panel 110. The unfiltered inlet air flow is prevented from entering the space between the inlet wall panel 130 and the first filter panel 110 by the cooperating sealing rims 116, 136. After passing through the second air passage 115 of the first filter panel 110, the unfiltered flow is divided into a first flow passing through the filter wall 112 of the first filter panel and a second flow passing through the filter wall 122 of the second filter panel 120. The unfiltered air flow is prevented from entering the first air passages 113, 123 by the cooperating first sealing rims 114, 124.

[0053] The air flow passing through the filter wall 112 of the first filter panel is filtered in this air passage through the filter wall 112 and enters the space between the first filter panel 110 and the inlet wall panel 130. From this space, the filtered air passes through the first air passages 113, 123 and enters the space between the second filter panel 120 and the outlet wall panel 140.

[0054] The second flow is filtered when passing through the filter wall 122 of the second filter panel and merges with the first, now filtered, air flow within the space between the second wall panel 120 and the outlet wall panel 140. From this space, the filtered air exits through the outlet opening 145 of the outlet wall panel 140.

[0055] Thus, the filter unit 100 forms a complete filter unit sealed from the surroundings except for the inlet opening 135 and the outlet opening 145. By this means, the outlet opening 145 of the filter unit 100 may be directly connected to the inlet opening of a mask (not shown) of an air - purifying respirator without the need for an additional filter housing or other sealing means.

[0056] An important advantage of the manufacturing method and the filter unit is that the structure of the filter unit 100 is modular and can be easily adapted to different applications by selecting the number of filter panels included in the stack. Thereby, the total area of the filter material contained in the filter unit and exposed to unfiltered air can be easily adapted by selecting any desired number of filter panels that form part of the stack.

[0057] Aspects of the present disclosure have mainly been described above with reference to some embodiments and examples thereof. However, other embodiments other than those disclosed above are equally possible within the scope of the invention as defined by the appended claims, as will be readily understood by those skilled in the art.

Claims

1. A method for manufacturing a filter unit (100) for an air purification respirator, comprising: providing a sheet (20) of filter material; feeding a portion of the filter material into an open mold (11, 12) of an injection molding machine; closing the mold (11, 12), thereby cutting filter walls (112, 122) from the sheet (20); holding the filter walls within the mold (11, 12); forming filter panel frames (111, 121) around the filter walls (112, 122) by injection molding a polymer material onto the filter walls (112, 122); opening the mold (11, 12); recovering filter panels (110, 120), the filter panels (110, 120) having the filter walls (112, 122) and the filter panel frames (111, 121) fixed thereto; A manufacturing method comprising the above steps.

2. The manufacturing method according to claim 1, wherein the filter material and the injected polymer material comprise the same polymer material.

3. The manufacturing method according to claim 2, wherein the same polymer material is PP or PA.

4. The manufacturing method according to any one of claims 1-3, including repeating steps for forming a plurality of filter panels (110, 120).

5. The manufacturing method according to any one of claims 1-4, wherein the step of closing the mold to cut the filter walls includes simultaneously cutting a plurality of filter walls, and the step of forming the filter panels includes simultaneously forming a plurality of filter panels corresponding to the plurality of filter walls.

6. providing an inlet wall panel (130) and an outlet wall panel (140); stacking a plurality of filter panels (110, 120), the inlet wall panel (130), and the outlet wall panel (140), and stacking the plurality of filter panels (110, 120) between the inlet wall panel (130) and the outlet wall panel (140);

7. The manufacturing method according to claim 6, including sealing and joining the peripheries of the plurality of filter panels (110, 120), the inlet wall panel (130), and the outlet wall panel (140).

8. The manufacturing method according to claim 7, wherein the periphery is sealed and joined by adhesion, heat fusion welding, ultrasonic welding, or mechanical engagement means.

9. A filter unit (100) for an air purification respirator, comprising: An inlet wall panel (130) having an air inlet opening (135); An outlet wall panel (140) having an air outlet opening (145); A plurality of filter panels (110, 120), each filter panel having a filter wall (112, 122) and a ventilation passage (113, 123), the filter panels (110, 120); A plurality of panels (110, 120, 130, 140) are stacked together in a sealed manner to form a stack of panels. The plurality of filter panels (110, 120) are disposed between the inlet wall panel (130) and the outlet wall panel (140). The stack defines an inner ventilation passage from the air inlet opening (135) through the filter walls (112, 122) and the ventilation passages (113, 123) to the air outlet opening (145), and the inner ventilation passage is sealed from the outside of the stack, the filter unit (100).

10. The filter unit according to claim 9, wherein the plurality of panels (110, 120, 130, 140) are planar.

11. Each panel (110, 120, 130, 140) includes a peripheral sealing portion (111a, 121b, 121b, 131, 141), and the peripheral sealing portion (111a, 121b, 121b, 131, 141) extends along the periphery of each panel (110, 120, 130, 140) and is arranged to make sealing contact with the corresponding peripheral sealing portions (111a, 111b, 121a, 121b, 131, 141) of adjacent panels (110, 120, 130, 140). The filter unit according to claim 9 or 10.

12. Each filter panel (110, 120) includes an inner sealing portion (114, 124), and the inner sealing portion (114, 124) extends around the ventilation passages (113, 123) and is arranged to make sealing contact with the corresponding inner sealing portions (114, 124) of adjacent filter panels (110, 120). The filter unit according to any one of claims 9-11.

13. Each filter panel (110, 120) includes a peripheral frame (111, 121) surrounding the filter wall (112, 122). The filter unit according to any one of claims 9-12.

14. The filter wall (112, 122) and the filter frame (111, 121) include the same polymer material. The filter unit according to any one of claims 9-13.

15. The plurality of filter panels (110, 120), the inlet wall panel (130), and the outlet wall panel (140) include the same polymer material. The filter unit according to any one of claims 9-14.

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