Abstract
Negative pressure device for treating and removing fluid from a wound has a housing having a first end connectable to the wound and an opposite second end, wherein the-housing is in a single piece, hollow and cylindrical. A piston slides inside the housing to generate the negative pressure, and a constant-force mechanism is loaded and activates the piston, the constant-force mechanism is fixed to the second end of the housing and to the piston and is placed inside the housing. A valve system draws air from the housing when the piston slides towards the first end and brings fluid into the housing when the piston slides towards the second end. The constant-force mechanism is entirely contained inside the housing, and the piston and the second end of the housing comprise a rear opening such as to allow a user to manually slide the piston and load the constant-force mechanism.
Claims
1. A negative pressure device for treating a wound and removing fluid from said wound, the device comprising: a longitudinal housing having a first end configured to be connected to the wound and a second end opposite the first end, wherein the longitudinal housing is a structure in a single piece, hollow and cylindrical, a piston inside the housing, the piston being slidable in the housing to generate a negative pressure, a constant-force mechanism configured to be loaded and operated by the piston, wherein said constant-force mechanism is fixed at the second end of the longitudinal housing and to the piston and is arranged inside the housing, and a valve system for drawing air out of the housing when the piston slides towards the first end of the housing and for bringing wound fluid into the housing when the piston slides towards the second end of the housing, wherein the constant-force mechanism is entirely contained inside the longitudinal housing where the piston slides and the second end of the longitudinal housing comprises a rear opening such as to allow the insertion of one or more fingers of an individual's hand to manually slide the piston and load the constant-force mechanism.
2. The device according to claim 1, wherein the housing comprises a rear cover curved at the second end and partially covering the back of the device.
3. The device according to claim 2, wherein the rear cover element comprises a fixing element for fixing the constant-force mechanism to the housing.
4. The device according to claim 1, wherein the constant-force mechanism comprises at least one constant-force spring fixed to the piston in a laminar manner which can be activated by the pressure exerted by one or more fingers of a single user.
5. The device according to claim 2, wherein the constant-force mechanism comprises a single constant-force spring mounted on a cylindrical support, wherein the spring is formed by a metallic band which can be wound around said cylindrical support, in which one end of the band is fixed to the cylindrical support and the other end of the band is provided with a connecting element, in particular a through hole, for connecting to the rear cover, wherein the metallic band follows the curved profile of the rear cover when connected to said rear cover.
6. The device according to claim 1, wherein the piston comprises a main body with a first surface defining a pressure chamber with the first end of the housing and the constant-force mechanism is confined, at least partially, in an inner region of said main body of the piston.
7. The device according to claim 6, wherein the main body of the piston comprises a second surface used to manually load the constant-force mechanism.
8. The device according to claim 1, wherein the valve system is placed at the first end of the longitudinal housing.
9. The device according to claim 1, wherein the valve system comprises two one-way valves.
10. The device according to claim 1, wherein the valve system comprises a cover element fixable to the first end of the longitudinal housing and a circular membrane positioned between the cover element and the first end of the longitudinal housing.
11. The device according to claim 10, wherein the cover element comprises a first opening for the entry of wound fluid and a second opening for the exit of air.
12. The device according to claim 11, wherein the longitudinal housing comprises a front portion at the first end, wherein said front portion comprises an inlet hole at the first opening of the cover element and an outlet hole at the second opening of the cover element.
13. The device according to claim 10, wherein the circular membrane consists of a central disc element and a circumferential element concentric with the disc element and positioned externally thereto, wherein the circumferential element acts as a gasket and is fixed between the cover element and the longitudinal housing.
14. The device according to claim 10, wherein the longitudinal housing comprises a front part at the first end, wherein said front part has a pointed profile and comprises two surfaces defining said tip and which are configured to be alternately contacted with a half of the circular membrane following the sliding of the piston inside the longitudinal housing.
15. The device according to claim 13, wherein the front portion of the housing comprises an outer central edge, the cover element comprises an inner central edge and the central disc of the circular membrane is divided into two half-discs following the crushing of said central disc between said outer central edge and said inner central edge.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1a-b show a front and rear schematic perspective depiction of the device according to an example of the invention.
[0047] FIG. 2a-b show a schematic perspective depiction of the device of FIG. 1.
[0048] FIG. 3a-b show a schematic perspective depiction of the piston and of the cover element of the device of FIG. 1.
[0049] FIG. 4a-b show a schematic depiction of the constant-force mechanism and the circular membrane of the device of FIG. 1.
[0050] FIG. 5 shows a schematic depiction of the device of FIG. 1 with exploded view.
[0051] FIG. 6a-b show a schematic depiction of the back (a) and the front (b) of the device of FIG. 1.
[0052] FIG. 7a-b show a schematic depiction of the device of FIG. 1 in longitudinal section along the cut A-A of FIG. 6a.
[0053] FIG. 8a-b show a schematic depiction of the device of FIG. 1 in longitudinal section along the cut B-B of FIG. 6a.
[0054] FIG. 9a-b show a schematic longitudinal section depiction of the device of FIG. 1 (a) and a detail of the valve system (b).
[0055] FIG. 10 shows a schematic depiction of the circular membrane.
[0056] FIG. 11 shows a schematic longitudinal section view of the device of FIG. 2.
[0057] FIG. 12a-b show the front part of the housing with and without circular membrane.
[0058] FIG. 13a-b show the back part of the cover element with and without circular membrane.
[0059] FIG. 14a-b show a front and rear schematic perspective depiction of the device according to another example of the invention.
[0060] FIG. 15a-b show a schematic perspective depiction of the device of FIG. 14.
[0061] FIG. 16a-b show a schematic perspective depiction of the piston and of the cover element of the device of FIG. 14.
[0062] FIG. 17a-b show a schematic depiction of the constant-force mechanism and the circular membrane of the device of FIG. 14.
[0063] FIG. 18 shows a schematic depiction of the device of FIG. 14 with exploded view.
[0064] FIG. 19 shows a schematic depiction of the back of the device of FIG. 14.
[0065] FIG. 20a-b show a schematic depiction of the device of FIG. 14 in longitudinal section along the cut A-A of FIG. 19.
[0066] FIG. 21a-b show a schematic depiction of the device of FIG. 14 in longitudinal section along the cut B-B of FIG. 19.
[0067] FIG. 22a-b show a schematic longitudinal section depiction of the device of FIG. 14 (a) and a detail of the valve system (b).
[0068] FIG. 23 shows a schematic depiction of the circular membrane.
[0069] FIG. 24a-b show a show a schematic longitudinal section depiction of the device of FIG. 14 with detail of the first end.
[0070] FIG. 25a-b show the front part of the housing with and without circular membrane.
[0071] FIG. 26a-b show the back part of the cover element with and without circular membrane.
[0072] FIG. 27a-b show a schematic depiction of the device of FIG. 14.
DETAILED DESCRIPTION
[0073] The main features of the device 1, 1′ will be described in more detail in the following figures.
[0074] The device 1, 1′ comprises a longitudinal housing 10. The housing 10 is cylindrical with a first end 101 configured to be connected to a wound and a second end 102. A piston 11 can slide inside the housing 10 which consists of a main body 21 and a first surface 22 defining a pressure chamber 17 with the first end 101 of the housing. The constant-force mechanism 12, 12′ is connected to the piston 11 and to a point of the housing 10 at the second end 102 and can be loaded to activate the piston 11. In particular, the constant-force mechanism 12, 12′ is inserted at least partially in an inner region 23 of the main body 21. It should be noted that a part of the constant-force mechanism 12, 12′ is outside this inner region 23 and connects to a point of the housing at the second end 102. The main body 21 comprises a second surface 24 which is utilized to manually load the constant-force mechanism. In other words, through the rear opening 14 of the housing 10 it is possible to push (for example using one or more fingers of an individual's hand) the piston 11 by acting directly on the second surface 24 and thus load the constant-force mechanism 12, 12′. The main body 21 of the piston 11 comprises a first surface 22 which, together with the inner walls and the first end 101 of the housing 10, defines a pressure chamber 17 within which negative pressure is generated. The device 1 further comprises a valve system 13 which acts as a vent for the air when the piston 11 slides in the housing 10. The valve system 13 can be positioned in any region of the housing 10 (such as at one end, the piston, or a side wall) as long as it ensures the exit of air from the housing 10 when the piston slides towards the first end 101 and fluid entry in the housing 10 (i.e., inside the pressure chamber 17) when the piston slides towards the second end 102. More details on the operation of the device will be described with reference to the following examples.
[0075] FIGS. 1a and 1b depict the negative pressure device 1 according to an example of the invention. The device 1 comprises a longitudinal housing 10 having a first end 101 configured to be connected to the wound and a second end 102 opposite the first end 101. The second end 102 of the longitudinal housing 10 comprises a rear opening 14 such as to allow the insertion of at least one finger of an individual's hand to manually slide a piston 11 inside the housing 10. The piston 11 (or rather the gasket 111 thereof) defines together with the inner walls and the first end 101 of the housing 10 a pressure chamber 17 inside which the negative pressure is generated. The movement of the piston 11 varies the volume inside the housing 10, i.e., the pressure chamber 17. In particular, as the volume increases, the air pressure is reduced, resulting in a subsequent suction from the wound region. FIG. 1a shows in particular the situation where the piston 11 is at the second end 102 of the housing 10 and the volume of the pressure chamber 17 is maximum. In this case, the constant-force mechanism 12 is not loaded. FIG. 1b instead shows the situation where the piston 11 is at the first end 101 of the housing 10 and the volume of the pressure chamber 17 is minimal. The sliding of the piston 11 towards the first end 101 of the housing is achieved by a thrust thereof through the rear opening 14. Thereby, the constant-force mechanism 12, which is fixed to the second end 102 of the housing 10 and at the same time attached to the piston 11, is loaded and the device 1 is ready for the suction process.
[0076] FIGS. 2a and 2b show a perspective view of the device of FIG. 1. The housing 10 and thus the pressure chamber 17 comprises two fixing points 103 at the second end 102 to allow the constant-force mechanism 12 to be fixed with the housing 10. Furthermore, the device 1 comprises a valve system 13 at the first end 101. In particular, the valve system 13 comprises a cover element 131 having a first opening 133 connected by means of a tube or cannula system to a special wound dressing positioned in the patient's tissue and a second opening 134 for the exit of air from the pressure chamber 17.
[0077] FIGS. 3a and 3b show a perspective view of the piston 11 and valve system 13. The piston 11 consists of a gasket 111 and a support 112. The constant-force mechanism 12 is connected to the support 112 of the piston 11 by means of first connectors 113 (described in detail in the following figures) and is connected to the housing 10 by means of second connectors 201 which interact with the fixing points 103 of the housing 10. The valve system 13 is composed of a cover element 131 and a circular membrane 132.
[0078] FIGS. 4a and 4b show a perspective view of the constant-force mechanism 12 and the circular membrane 132. The constant-force mechanism 12 according to an example comprises two constant-force springs 121 arranged one above the other in the longitudinal direction of the housing 10 and each mounted on a cylindrical support 122. Specifically, each constant-force spring 121 is made of a metallic band wound around said cylindrical support 122, in which one end of the band is fixed to the cylindrical support 122 while the other end is provided with a connecting element 123, for example a through hole, to connect to the second connectors 201 of the constant-force mechanism 12. The two springs 121 are wound around the supports 122 according to two opposite winding directions. The circular membrane 132 consists of a central disc element 135 and a circumferential element 136 concentric with the disc element 135 and positioned externally thereto. More details of the circular membrane 132 will be described in the following figures.
[0079] FIG. 5 shows an exploded view of the device 1 according to the example of FIGS. 1-4. As shown above, the cover element 131 comprises a first opening 133 connected by means of a tube or cannula system to the patient's wound and a second opening 134 for the exit of air from inside the pressure chamber 17. Similarly, the housing 10 comprises an inlet hole 1011 that can be coupled to the first opening 133 and an outlet hole 1012 that can be coupled to the second opening 134. According to this example, the housing 10 has a cylindrical shape and therefore the gasket 111 of the piston 11 has a circular shape of the same size as the cross-section of the housing 10 so as to perfectly adhere to the inner walls of the housing 10. From the figure it can be noted that the first connectors 113 between the piston 11, i.e., the support 112, and the constant-force mechanism 12, i.e., the springs 121, consist of two pins which pass through two holes in the support 112 and are fixed to the cylindrical supports 122. Furthermore, from the figure it can be noted that the second connectors 201 between the housing 10 at the second end 102 and the constant-force mechanism 12, i.e., the springs 121, consist of two pins which pass through two holes 103 in the housing 10 and connect to the connecting elements 123 of the springs 121 at one of the ends thereof. The scaled indicator 16 extending longitudinally outside the housing 10 marks the load state of the device.
[0080] FIG. 6a shows the back of the device 1. Specifically, the figure shows the presence of a rear opening 14 through which one or more fingers of a hand can be inserted to activate and load the constant-force mechanism 12. FIG. 6b instead shows the front part of the device 1 in which the first and second openings 133, 134 are present for the connection with the wound and for the exit of air from the pressure chamber 17.
[0081] FIGS. 7a and 7b show the device 1 according to a longitudinal section along the cut A-A of FIG. 6a, while FIGS. 8a and 8b illustrate the device 1 according to a longitudinal section along the cut B-B of FIG. 6a. These figures show the details of the interior of the device 1 and specifically, the pressure chamber 17 represented by the volume defined by the piston 11, i.e., the gasket 111, the inner walls of the housing 10 and the first end 101 of the housing 10, i.e., the upper part of the housing 10. Furthermore, the figures show the arrangement of the springs 121 forming the constant-force mechanism 12 and the connection thereof with the piston 11, i.e., the support 112.
[0082] FIGS. 9a and 9b show the device 1 in longitudinal section and a detail of the valve system 13 positioned at the first end 101 of the housing 10. From FIG. 9b it can be noted that the housing 10 comprises an inlet hole 1011 and an outlet hole 1012 connected to the valve system 13. The circular membrane 132 is configured to fit the surfaces of the cover element 131 and the top of the housing 10. In particular, the circular membrane comprises two half-discs 1351 and 1352 which can move alternately to close or open the air or fluid passages determined by the first and second openings 133, 134 on the cover element 131 and by the inlet and outlet hole 1011, 1012 on the upper part of the housing 10.
[0083] FIG. 10 shows the circular membrane 132 in detail. The membrane 132 consists of a central disc element 135 and a circumferential element 136 concentric with the disc element 135 and positioned externally thereto. The circumferential element 136 acts as a gasket and is fixed between the cover element 131 and the longitudinal housing 10, i.e., the top of the housing 10. The membrane 132 comprises a central hole 137 for improving the alignment thereof at the cover element 131 and the housing 10 and comprises at least two side edges 139 connecting the central disc 135 to the circumference element 136. The central disc 135 is divided into two half-discs 1351, 1352 which may be referred to as “semi-valves”. The division of the central disc 135 in two is ensured by the crushing of said central disc 135 between an outer central edge 153 present on the upper part of the housing 10, i.e., on the pointed profile 15 defined by the inclined surfaces 151 and an inner central edge 138 present on the cover element 131.
[0084] FIG. 11 shows a schematic depiction of the device 1 in which the presence of a scaled indicator 16 positioned on the surface of the housing 10 is highlighted, for example the outer surface and a corresponding piston indicator 18 placed on the support 112 of the piston 11. The position of the latter indicator 18 changes depending on the load state of the device 1, i.e., depending on the position of the piston 11 relative to the first end 101 or second end 102 of the housing 10. Advantageously, the scaled indicator 16 defines the load state of the device 10 with different colours.
[0085] FIG. 12a shows the front portion 104 of the housing 10 which is defined by a pointed profile 15 with two inclined surfaces 151 (consider, for example, the sections in FIG. 8a). The inlet hole 1011 and the outlet hole 1012 are on these surfaces. The tip of the front portion 104 of the housing 10 is defined by the centre edge 153 used to crush the circular membrane 132 and divide it into two half-discs 1351, 1352. The front portion 104 of the housing 10 further comprises a central hole 105 for aligning with the membrane 132 by means of the corresponding hole 137.
[0086] FIG. 12b shows the front 104 of the housing 10 of FIG. 12a on which the membrane 132 lies. The circumferential element 136 of the membrane 132 acts as a gasket while the central disc 135 acts as an alternating valve as explained above.
[0087] FIG. 13a shows the back of the cover element 131 having the first opening 133 and the second opening 134. In particular, the cover element comprises an inner pin 1311 which serves for the alignment of the membrane 132 with the front portion 104 of the housing 10 by inserting said pin 1311 with the central holes 137 and 105, respectively of the membrane 132 and the front portion 104 of the housing 10. Furthermore, there is a central inner edge 138 which serves to define the two half-discs 1351 and 1352 of the circular membrane 132 following the crushing of the central disc 135 of the membrane 132 between said central inner edge 138 and the central outer edge 153 of the front 104 of the housing 10. To ensure the maximum seal, the outer part of the diameter 1312 of the cover element 131 is coupled with the circumferential element 136 of the circular membrane 132.
[0088] FIG. 13b shows the back of the cover element 131 of FIG. 13a on which the membrane 132 lies. The circumferential element 136 of the membrane 132 acts as a gasket while the central disc 135 acts as an alternating valve as explained above. The inner pin 1311 passes through the hole 137 of the membrane 132.
[0089] It should be noted that the device 1 of FIGS. 1-13 shows a valve system 13 placed at the first end 101. However, as described above, the valve system 13 can advantageously be positioned differently in other parts of the device 1.
[0090] FIGS. 14a and 14b depict the negative pressure device 1′ according to another example of the invention. This device differs from the previous one essentially by the mere fact that the constant-force mechanism consists of a single spring. Thus, identical components between the two devices will not necessarily be described again. The reference numbers of identical components therefore remain unchanged.
[0091] As in the case of the device 1, of FIGS. 1-13, the device 1′ comprises a longitudinal housing 10 having a first end 101 configured to be connected to the wound and a second end 102 opposite the first end 101. The second end 102 of the longitudinal housing 10 comprises a rear opening 14 such as to allow the insertion of at least one finger of an individual's hand to manually slide a piston 11 inside the housing 10. The piston 11 (or rather the gasket 111 thereof) defines together with the inner walls and the first end 101 of the housing 10 a pressure chamber 17 inside which the negative pressure is generated. The movement of the piston 11 varies the volume inside the housing 10, i.e., the pressure chamber 17. In particular, as the volume increases, the air pressure is reduced, resulting in a subsequent suction from the wound region.
[0092] FIGS. 15a and 15b show a perspective view of the device of FIG. 14. The housing 10 and therefore the pressure chamber 17 comprises a curved rear cover 19 partially covering the back of the device 1′ at the second end 102. There is a fixing element 191 for the constant-force mechanism 12′ on this cover 19. The cover element 131′ instead covers the first end 101 of the device 1′.
[0093] FIGS. 16a and 16b show a perspective view of the piston 11 and the cover element 131′. The piston 11 consists of a gasket 111, a support 112 and a component 114. From the figure it can be noted that the constant-force mechanism 12′ comprises a single spring 121 which can be fixed at an end thereof to the rear cover 19 by corresponding fixing means 1211. In addition to the first and second openings 133, 134, the cover element 131′ comprises a central alignment hole 1313.
[0094] FIGS. 17a and 17b show a perspective view of the constant-force mechanism 12′ and the circular membrane 132. The constant-force mechanism 12′ according to this example comprises a constant-force spring 121 mounted on a cylindrical support 122. Specifically, the constant force spring 121 is made of a metallic band wound around said cylindrical support 122, in which one end of the band is fixed to the cylindrical support 122 while the other end is provided with a connecting element 123, for example a through hole, to connect to the rear cover 19 by fixing means 1211. The circular membrane 132 consists of a central disc element 135 and a circumferential element 136 concentric with the disc element 135 and positioned externally thereto.
[0095] FIG. 18 shows an exploded view of the device 1 according to the example of FIGS. 14-17. As shown above, the cover element 131′ comprises a first opening 133 connected by means of a tube or cannula system to the patient's wound and a second opening 134 for the exit of air from inside the pressure chamber 17. Similarly, the housing 10 comprises an inlet hole 1011 that can be coupled to the first opening 133 and an outlet hole 1012 that can be coupled to the second opening 134. According to this example, the housing 10 has a cylindrical shape and therefore the gasket 111 of the piston 11 has a circular shape of the same size as the cross-section of the housing 10 so as to perfectly adhere to the inner walls of the housing 10. From the figure it can be noted that the device 1′ comprises a pin 113′ which extends from the support 112, passes through the cylindrical support 122 and is fixed to the additional component 114 which holds everything in position. The figure also shows the presence of a scaled indicator 16 positioned outside on the housing 10 to indicate the load state of the device 1′.
[0096] FIG. 19 shows the back of the device 1′. Specifically, the figure shows the presence of a rear opening 14 through which one or more fingers of a hand can be inserted to activate the constant-force mechanism 12′. From the figure it can be seen that the rear cover 19 partially covers the opening 14.
[0097] FIGS. 20a and 20b show the device 1 according to a longitudinal section along the cut A-A of FIG. 19, while FIGS. 21a and 21b illustrate the device 1 according to a longitudinal section along the cut B-B of FIG. 19. These figures show the details of the interior of the device 1′ and specifically, the pressure chamber 17 represented by the volume defined by the piston 11, i.e., the gasket 111, the inner walls of the housing 10 and the first end 101 of the housing 10, i.e., the upper part of the housing 10. Furthermore, the figures show the arrangement of the spring 121 forming the constant-force mechanism 12 and the connection thereof with the piston 11, i.e., the support 112.
[0098] FIGS. 22a and 22b show the device 1′ in longitudinal section and a detail of the valve system 13 positioned at the first end 101 of the housing 10. From FIG. 22b it can be noted that the housing 10 comprises an inlet hole 1011 and an outlet hole 1012 connected to the valve system 13. The circular membrane 132 is configured to fit the surfaces of the cover element 131′ and the top of the housing 10. In particular, the circular membrane 132 comprises two half-discs 1351 and 1352 which can move alternately to close or open the air or fluid passages determined by the first and second openings 133, 134 on the cover element 131′ and by the inlet and outlet hole 1011, 1012 on the upper part of the housing 10. To hold in position the membrane 132, the cover element 131′ and the housing 10 in place, the upper part of the housing 10 comprises a pin 154 which passes through the central hole 137 of the membrane 132 and the central hole 1313 of the cover element 131′. It can also be noted from the figure that the profile of the outer surface of the cover element 131′ is not flat but comprises a raised region at the second opening 134 to facilitate the exit of air. This configuration of the cover element 131′ can also be applied to the example of FIGS. 1-13 described above. In particular, the circumferential element 136 is configured so that it can be crushed between the covering element 131′ and the housing 10.
[0099] FIG. 23 shows the circular membrane 132 in detail. As in the previous example, the membrane 132 consists of a central disc element 135 and a circumferential element 136 concentric with the disc element 135 and positioned externally thereto. The circumferential element 136 acts as a gasket and is fixed between the cover element 131 and the longitudinal housing 10, i.e., the top of the housing 10. The membrane 132 comprises a central hole 137 for improving the alignment thereof at the cover element 131′ and the housing 10 and comprises at least two side edges 139 connecting the central disc 135 to the circumference element 136. The central disc 135 is divided into two half-discs 1351, 1352 which may be referred to as “semi-valves”. The division of the central disc 135 in two is ensured by the crushing of said central disc 135 between a central edge 153 present on the upper part of the housing 10, i.e., on the pointed profile 15 defined by the inclined surfaces 151 and an inner central edge 138 present on the cover element 131.
[0100] FIGS. 24a and 24b show a schematic depiction of the device 1′ with detail on the front part 104 of the housing 10 cut to ¾. FIG. 24b shows the alignment of the circular membrane 132 with respect to the housing 10 and the cover element 131′ determined by inserting the pin 154 in the central holes 137 and 1313 of the central membrane 132 and cover element 131′, respectively.
[0101] FIG. 25a shows the front 104 of the housing 10 which is defined by a pointed profile 15 with two inclined surfaces 151. The inlet hole 1011 and the outlet hole 1012 are present on these surfaces 151 (consider for example the section in FIG. 20a). The tip of the front portion 104 of the housing 10 is defined by the centre edge 153 used to crush the circular membrane 132 and divide it into two half-discs 1351, 1352. The front portion 104 of the housing 10 further comprises a central pin 154 for aligning with the membrane 132 by means of the corresponding hole 137.
[0102] FIG. 25b shows the front 104 of the housing 10 of FIG. 25a on which the membrane 132 lies. In particular, the membrane 132 lies on the outer portion 106 of the housing 10. The circumferential element 136 of the membrane 132 acts as a gasket while the central disc 135 acts as an alternating valve as explained above.
[0103] FIG. 26a shows the back of the cover element 131′ having the first opening 133 and the second opening 134. In particular, the cover element comprises a central hole 1313 which serves for aligning the membrane 132 with the front part 104 of the housing 10 by inserting the pin 154 of the front part 104 of the housing 10. Furthermore, there is a central inner edge 138 which serves to define the two half-discs 1351 and 1352 of the circular membrane 132 following the crushing of the central disc 135 of the membrane 132 between said central inner edge 138 and the central edge 153 of the front 104 of the housing 10. To ensure the maximum seal, the outer part of the diameter 1312 of the cover element 131′ is coupled with the circumferential element 136 of the circular membrane 132.
[0104] FIG. 26b shows the back of the cover element 131′ of FIG. 13a on which the membrane 132 lies. The circumferential element 136 of the membrane 132 acts as a gasket while the central disc 135 acts as an alternating valve as explained above. The inner pin 154 passes through the hole 137 of the membrane 132.
[0105] FIGS. 27a and 27b show a schematic depiction of the device 1′ in which the presence of a scaled indicator 16 positionable on the surface of the housing 10 is highlighted, for example the outer surface and a corresponding piston indicator 18 placed on the support 112 of the piston 11. It should be noted that these figures show only some components of the device 1′. For example, the housing 10 and the constant-force mechanism 12′ are omitted from the figures. The position of the indicator 18 changes depending on the load state of the device 1, i.e., depending on the position of the piston 11 relative to the first end 101 or second end 102 of the housing 10. Advantageously, the scaled indicator 16 defines the load state of the device 10 with different colours.
[0106] It should be noted that the device 1′ of FIGS. 14-27 shows a valve system 13 placed at the first end 101. However, as described above, the valve system 13 can advantageously be positioned differently in other parts of the device 1.
[0107] A person skilled in the art can perform several and further modifications and variants to the device 1, 1′ described above, in order to satisfy further and contingent needs, all said modifications and variants however included within the scope of protection of the present invention as defined by the appended claims.
