Method for producing filter unit for air purification respirator and such filter unit

Abstract

A method of manufacturing a filter unit (100) for an air purifying respirator is disclosed, the method comprising the steps of: providing a sheet (20) of filter material; feeding a portion of the filter material to an open mold (11, 12) of the injection molding machine; closing the mould (11, 12) to cut the filter wall (112, 122) from the sheet (20); holding the filter wall in the mould (11, 12); forming a filter panel frame (111, 121) around the filter walls (112, 122) by injection molding a polymeric material onto the filter walls (112, 122); opening the mould (11, 12); and removing the filter panel (110, 120), the filter panel (110, 120) comprising a filter wall (112, 122) and a filter panel frame (111, 121) secured to the filter wall. A filter unit for an air purifying respirator is also disclosed.

Description

Technical Field

[0001] The present invention generally relates to air purifying respirators, and more particularly to a method of manufacturing a filter unit for an air purifying respirator. The present invention also discloses a filter unit for an air purifying respirator. Background Art

[0002] An air purifying respirator is an air filtering device that prevents the inhalation of large and small particles by removing contaminants through filtration or absorption. Air purifying respirators can be either passive PAPRs or active PAPRs. PAPRs have significant advantages over APRs because PAPRs require only a simple fit test and do not increase the work of breathing. Because PAPRs provide positive pressure inside the mask, they also reduce the risk of leakage into the mask due to the growth of beards, wrinkles, etc.

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

[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 easy replacement, light weight and small size that does not hinder the wearer, environmentally friendly, and it should be able to be manufactured quickly at low cost.

[0005] One known type of filter unit comprises a relatively thin sheet of filter media which has been folded into an accordion-like filter insert which is inserted into a filter housing and attached in a sealed manner to the inner wall of the filter housing, wherein the filter housing has an air inlet and an air outlet. Another known type of filter unit comprises a relatively thick felt-like filter material, one or more layers of which are inserted into the filter housing and attached in a sealed manner to the inner wall. Summary of the invention

[0006] It is an object of the present invention to provide an improved method of manufacturing a filter element for an air purifying respirator.

[0007] Another object is to provide a method which allows the production of filter units at high speed and low cost.

[0008] A further object is to provide a method which allows modular manufacturing so that the total filter area of ​​the filter unit can be easily varied.

[0009] A further object is to provide a method which allows easy recovery of the filter unit after use.

[0010] Yet another object is to provide an improved filter unit for an air purifying respirator.

[0011] In general, unless otherwise expressly defined herein, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field. Unless otherwise expressly stated, all references to "a / an / the element, means, component, mode, step, etc." should be broadly understood to refer to at least one example of the element, means, component, mode, step, etc. Unless otherwise expressly stated, the steps of any method disclosed herein do not have to be performed in the exact order disclosed.

[0012] According to a first aspect, the present invention provides a method of manufacturing a filter unit for an air purifying respirator as defined in the accompanying claim 1. The method comprises the steps of providing a sheet of filter material; feeding a portion of the filter material to an open mold of an injection molding machine; closing the mold to cut out a filter wall from the sheet; retaining the filter wall in the mold; forming a filter panel frame around the filter wall by injection molding a polymer material onto the filter wall; opening the mold; and removing the filter panel, the filter panel comprising the filter wall and the filter panel frame fixed to the filter wall.

[0013] Therefore, the method allows to easily produce a filter panel forming a part of a filter unit at a single operating station in the combined filter material cutting and filter panel frame injection molding operation. This reduces the need for intermediate processing and storage of the components. The method also allows high-speed manufacturing to be achieved at low cost. The operating station preferably includes a mold formed by at least two half molds or components, and at least two half molds or components can be moved relative to each other to open and close the mold. At least one of the half molds or components includes a cutting tool, which is arranged to cut out a filter wall from the filter material sheet when the mold is closed.

[0014] Furthermore, the method also allows a modular manufacturing process and a corresponding modular construction of the filter unit. This is because the method allows any number of identical filter panels obtained by the method to be stacked together when forming the final filter unit. In this way, the total filter area of ​​the filter unit can be easily adapted to various requirements.

[0015] In some embodiments, the filter material and the injected polymer material comprise the same polymer material. This allows the filter frame to be bonded to the filter wall by material fusion during the injection molding process. Additionally, this facilitates recycling of the filter panel, as the entire panel can be recycled as a unit without the need to separate the filter wall from the filter panel frame.

[0016] The same polymer material may be PP (polypropylene) or PA (polyamide).

[0017] The method may include repeating the step of forming a plurality of filter panels.

[0018] Alternatively or in combination, the step of closing the mold to cut out the filter walls may include: cutting out a plurality of filter walls simultaneously; and the step of forming the filter panel may include: forming a plurality of filter panels simultaneously, the plurality of filter panels corresponding to the plurality of filter walls.

[0019] The method may further comprise the steps of: providing an inlet wall panel and an outlet wall panel; stacking a plurality of filter panels, the inlet wall panel and the outlet wall panel, so that a plurality of filter panels are stacked between the inlet wall panel and the outlet wall panel. In this way, the entire filter unit may be easily manufactured, the entire filter unit comprising the inlet wall panel, the outlet wall panel and any desired number of intermediate filter panels.

[0020] The inlet wall panel and the outlet wall panel can be produced by injection molding of suitable materials. Preferably, the inlet wall panel and the outlet wall panel comprise the same material as one or more filter panels of the filter unit. In this way, the recovery of the entire filter unit is facilitated. In addition, using the same material allows the panels to be combined together in a sealed manner by material fusion to form a sealed filter unit.

[0021] The method may include joining the peripheral edges of the filter panel, the inlet wall panel, and the outlet wall panel in a sealed manner. This allows the filter unit including the inlet wall panel, the outlet wall panel, and one or more intermediate filter panels to be directly connected to the air purifying respirator without being contained in or attached in a sealed manner to any airtight housing or similar additional components, thereby preventing ambient air from mixing with the filtered air flow in the filter unit.

[0022] The peripheral edges may be joined in a sealed manner by gluing, heat fusing, ultrasonic welding or by means of mechanical engagement means.

[0023] According to a second aspect, the present application provides a filter unit for an air purifying respirator as defined in the attached claim 9. The filter unit comprises: an inlet wall panel having an air inlet opening; an outlet wall panel having an air outlet opening; and a plurality of filter panels, each filter panel having a filter wall and an air through-channel, wherein: the panels are stacked together in a sealed manner to form a stack of panels, in which the filter panel is arranged between the inlet wall panel and the outlet wall panel, the stack defining an internal air channel, the internal air channel starting from the air inlet opening, passing through the filter wall and the air through-channel to the outlet opening, the internal air channel being sealed from the outside of the stack.

[0024] In an embodiment of the filter unit, the panel is flat.

[0025] Each panel may include a perimeter seal extending along the perimeter of the panel and arranged to be in sealing contact with a corresponding perimeter seal of an adjacent panel.

[0026] Each filter panel may comprise an inner sealing portion extending around the air through-channel and arranged to be in sealing contact with a corresponding inner sealing portion of an adjacent filter panel.

[0027] Each filter panel may comprise a perimeter frame surrounding the filter wall.

[0028] The filter wall and the filter frame may comprise the same polymer material.

[0029] The filter panel, the inlet wall panel and the outlet wall panel may comprise the same polymeric material.

[0030] Other objects and advantages of the method and the full-face mask appear from the following description of embodiments and from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Various aspects and embodiments are described below by way of example with reference to the accompanying drawings, in which:

[0032] Figure 1 A cross-sectional view schematically illustrates steps of one embodiment of a method for manufacturing a filter unit.

[0033] Figure 2a and Figure 2b are perspective views from different angles of a filter unit manufactured by one embodiment of the method.

[0034] Figure 3a and Figure 3b yes Figure 2a and Figure 2b Exploded perspective views of the filter unit at different angles shown in FIG. DETAILED DESCRIPTION

[0035] Various aspects of the present application will be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the present application are shown.

[0036] However, these aspects can be embodied in many different forms and should not be construed as limiting. Instead, these embodiments are provided by way of example so that this application will be thorough and complete and fully convey the scope of all aspects of the application to those skilled in the art. The same number refers to the same element throughout the specification.

[0037] Figure 1The manufacturing station and the steps of the manufacturing method according to one embodiment are schematically shown. The manufacturing station comprises an injection molding machine 10 having a first mold half 11 and a second mold half 12, the second mold half 12 being movably engaged and disengaged with 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 structure 12a for forming, together with the cavity 11a, a filter panel to be manufactured ( Figure 1 The second half mold includes a space of the shape of the filter wall (not shown). In addition, the second half mold includes a cutting tool 13. In the example shown, the cutting tool 13 includes a knife. However, the cutting tool may include other devices for cutting out or cutting off the filter wall from the filter material sheet 20. Such other devices may include a punching device, a thermal cutting device, etc. The cutting tool may be arranged in either of the two half molds, or may include two or more cooperating tools arranged in the two half molds. The cutting tool 13 has a shape corresponding to the peripheral shape of the filter wall to be cut.

[0038] The supply roller 21 of the filter material formed by the sheet is arranged to supply the filter material sheet 20 between the first half mold 11 and the second half mold 12 when the mold is opened. The free end of the filter material sheet 20 is received on the collecting roller 22. The supply roller and the collecting roller 22 are arranged to keep the sheet stretched or tensioned during the cutting operation. The filter material can include various different materials with filtering properties. In the example shown, the sheet includes the non-woven fiber of PP. However, other examples of suitable filter materials include PTFE (polytetrafluoroethylene) and PA (polyamide).

[0039] In the exemplary embodiment of the method for manufacturing the filter unit shown, when the mold is opened, the filter material sheet 20 is provided between the first half mold 11 and the second half mold 12. Then, the mold is closed, whereby the cutting tool 13 cuts out a part of the filter material. The cut-out portion of the filter material is held in place in the mold cavity 11a by the clamping action applied by the first half mold 11 and the second half mold 12 of the cooperation. Alternatively or in combination, the mold can be provided with a separate clamping device (not shown) for holding the cut-out portion of the filter material in the mold cavity 11b. While keeping the mold closed and holding the cut-out portion of the filter material in the mold cavity 11a, the polymer material is injected into the mold cavity 11a through the channel 11b arranged in the first half mold 11. The injected polymer material can be selected from a wide range of thermoformable polymers. Preferably, the injection material should be fused with the filter material so that the injection material is firmly fixed to the filter material when forming the filter panel. For example, the injection material can include the same polymer material as the filter material. In the example shown, both the filter material and the injection material include PP. In an alternative not shown, both the filter material and the injection material comprise PA.

[0040] The mold cavity 11a is formed so that the injected material forms a rigid frame around the cut-out portion of the filter material when hardened, which is fixed to the filter material. When the injected material has hardened, the mold is opened and the filter panel including the filter wall and the filter frame fixed to the filter wall is taken out from the mold cavity 11a.

[0041] In an alternative not shown, the first mold half comprises a plurality of mold cavities, and the second mold half comprises a corresponding number of corresponding geometric structures and a corresponding number of cutting tools. In such an embodiment, the filter material sheet is fed between the mold halves so that the filter material sheet overlaps all mold cavities. Such an embodiment allows a plurality of filter panels to be produced in each injection molding cycle of the injection molding machine.

[0042] In order to complete the filter unit, the inlet wall panel and the outlet wall panel can be produced by injection molding in a separate injection molding machine. Alternatively, the inlet wall panel and / or the outlet wall panel can be injection molded simultaneously with one or more filter panels in the same injection molding machine. Since the inlet wall panel and the outlet wall panel usually do not include any filter material, the mold cavity for forming these wall panels does not need to be covered by the filter material when the mold is closed.

[0043] In another alternative not shown, the mold halves may include mold cavities and corresponding mold geometries for forming one or more filter panels, inlet wall panels, and outlet wall panels, which are formed as one integral piece, wherein pairs of panels are interconnected by corresponding bridge portions. The bridge portions may act as hinges so that the panels may be folded in a zigzag configuration to form a stack of panels, with the one or more filter panels being arranged between the inlet wall panel and the outlet wall panel.

[0044] After filter panel, inlet wall panel and outlet wall panel have been provided in the above-mentioned either way, these panels are stacked one on the top of another, and one or more filter panels are arranged between the inlet wall panel and the outlet wall panel.Then, the peripheral edge of the panel is linked together in a sealed manner so that the inside of the filter unit comprising the stack of panels is sealed and isolated from the surrounding atmosphere.This can be achieved by mechanical engagement means, which makes the stacked panels clamped to contact with sealing.Alternately or in combination, the edge of the panel can be linked to each other by bonding, thermal fusion and / or ultrasonic welding.

[0045] In this way, the filter unit is easy to manufacture in a fast and cost-effective manner. The resulting filter unit can be directly attached to the mask of an air-purifying respirator without the need for any additional filter housing.

[0046] Figure 2a and Figure 2bA perspective view of an assembled exemplary filter unit 100 is shown respectively. Figure 3a and Figure 3b An exploded perspective view of the filter unit 100 is shown respectively.

[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, wherein the first filter panel 110, the second filter panel 120, the inlet wall panel 130 and the outlet wall panel 140 are stacked together, wherein the filter panels 110 and 120 are arranged between the inlet wall panel 130 and the outlet wall panel 140.

[0048] Both filter panels 110, 120 are manufactured as described above and comprise filter panel frames 111, 121 and filter walls 112, 122, wherein the filter walls are made of air permeable filter material and are surrounded by the filter frames 111, 121. Each filter frame 111, 121 has two peripheral seals 111a, 111b, 121a, 121b facing in opposite directions.

[0049] The inlet wall panel 130 and the outlet wall panel are generally air-impermeable except at the inlet opening 135 and the outlet opening 145. Each of the inlet wall panel 130 and the outlet wall panel 140 comprises a perimeter seal 131 , 141 facing the adjacent filter panel 110,120.

[0050] When stacked, the perimeter seal 131 of the inlet wall panel is in sealing contact with the upper perimeter seal 111a of the first filter panel 110. Correspondingly, the lower perimeter seal 111b of the first filter panel 110 is in sealing contact with the upper perimeter seal 121a of the second filter panel 120, and the lower perimeter seal 121b of the second filter panel is in sealing contact with the perimeter seal 141 of the outlet wall panel 140. In this way, the interior of the filter unit 100 is sealed from the surrounding atmosphere except at the inlet opening 135 and the outlet opening 145.

[0051] Both filter panels 110, 120 also have first air through-channels 113, 123 surrounded by cooperating first sealing edges 114, 124. The first filter panel 110 arranged adjacent to the inlet wall panel 130 also has a second air through-channel 115 aligned with an inlet opening 135 arranged in the inlet wall panel 130. The second air through-opening 115 and the inlet opening 135 are surrounded by respective cooperating second sealing edges 116, 136.

[0052] exist Figures 2a to 3bIn the embodiment of the present invention, unfiltered air flow is represented by solid arrows, and filtered air flow is represented by dotted arrows. When filter panels 110, 120, inlet wall panel 130 and outlet wall panel 140 have been stacked and sealed as described above, air from the surrounding enters the filter unit 100 through the inlet opening 135 in the inlet wall panel, and continues to pass through the second straight-through opening 115 in the first filter panel 110. Prevent unfiltered inlet air flow from entering the space between the inlet wall panel 130 and the first filter panel 110 by cooperative sealing edges 116, 136. After having passed through the second straight-through opening 115 in the first filter panel 110, unfiltered air flow is divided into a first flow through the filter wall 112 of the first filter panel and a second flow through the filter wall 122 of the second filter panel 120. Prevent unfiltered air flow from entering the first air straight-through passage 113, 123 by cooperative first sealing edges 114, 124.

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

[0054] The second airflow is filtered while passing through the filter wall 122 of the second filter panel and joins with the currently filtered first airflow in the space between the second wall panel 120 and the outlet wall panel 140. The filtered air flows out from the space through the outlet opening 145 in the outlet wall panel 140.

[0055] Thus, filter unit 100 forms a complete filter unit that is sealed from the surrounding environment except at inlet 135 and outlet 145. In this way, outlet opening 145 of filter unit 100 can be directly connected to an inlet opening in a mask (not shown) of an air purifying respirator without the need for any additional filter housing or other sealing means.

[0056] An important advantage of the manufacturing method and filter unit is that the construction 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. Thus, the total area of ​​filter material included in the filter unit and exposed to unfiltered air can be easily adjusted by selecting any desired number of filter panels forming part of the stack.

[0057] Various aspects of the present application are mainly described on the basis of reference to a few embodiments and examples thereof. However, as is readily appreciated by those skilled in the art, other embodiments than the embodiments disclosed above are equally possible within the scope of the present application as defined by the attached patent claims.

Claims

1. A method for manufacturing a filter unit (100) for an air purifying respirator, the method comprising the following steps: 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 molds (11, 12) to cut filter walls (112, 122) from the sheet (20); retaining the filter wall in the mold (11, 12); forming a filter panel frame (111, 121) around the filter wall (112, 122) by injection molding a polymer material onto the filter wall (112, 122); Opening the mold (11, 12); as well as The filter panel (110, 120) is taken out, wherein the filter panel (110, 120) includes the filter wall (112, 122) and the filter panel frame (111, 121) fixed to the filter wall.

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

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

4. The method according to any one of claims 1 to 3, comprising: The steps of forming a plurality of filter panels (110, 120) are repeated.

5. The method according to any one of claims 1 to 4, in, The step of closing the mold to cut out the filter wall comprises: cutting out a plurality of filter walls simultaneously; and The step of forming the filter panel includes: forming a plurality of filter panels at the same time, and the plurality of filter panels correspond to the plurality of filter walls.

6. The method according to claim 4 or 5, comprising the following steps: providing an inlet wall panel (130) and an outlet wall panel (140); The plurality of filter panels (110, 120), the inlet wall panel (1130) and the outlet wall panel (140) are stacked such that the plurality of filter panels (110, 120) are stacked between the inlet wall panel (130) and the outlet wall panel (140).

7. The method according to claim 6, comprising: The peripheral edges of the filter panels (110, 120), the inlet wall panel (130) and the outlet wall panel (140) are joined in a sealing manner.

8. The method according to claim 7, wherein: The peripheral edges are joined in a sealed manner by gluing, heat welding, ultrasonic welding or by means of mechanical engagement.

9. A filter unit (100) for an air purifying respirator, the filter unit comprising: an inlet wall panel (130) having an air inlet opening (135); an outlet wall panel (140) having an air outlet opening (145); and A plurality of filter panels (110, 120), each filter panel having a filter wall (112, 122) and an air through-channel (113, 123), wherein: The panels (110, 120, 130, 140) are stacked together in a sealed manner to form a stack of panels, in which the filter panels (110, 120) are arranged between the inlet wall panel (130) and the outlet wall panel (140), and the stack defines an internal air channel, which starts from the air inlet opening (135), passes through the filter wall (112, 122) and the air through-channel (113, 123) to reach the outlet opening (145), and the internal air channel is sealed from the outside of the stack.

10. The filter unit according to claim 9, wherein: The panels (110, 120, 130, 140) are flat.

11. The filter unit according to claim 9 or 10, wherein: Each panel (110, 120, 130, 140) includes a peripheral seal (111a, 111b, 121a, 121b, 131, 141), which extends along the periphery of the panel (110, 120, 130, 140) and is arranged to be in sealing contact with the corresponding peripheral seal (111a, 111b, 121a, 121b, 131, 141) of the adjacent panel (110, 120, 130, 140).

12. The filter unit according to any one of claims 9 to 11, wherein: Each filter panel (110, 120) comprises an inner seal (114, 124) extending around the air through-channel (113, 123) and arranged to be in sealing contact with a corresponding inner seal (114, 124) of an adjacent filter panel (110, 120).

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

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

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

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