AIR PUMP WITH PRESSURE INDICATION

Abstract

A manually operable pump for cooperation with a container to reduce pressure inside the container; the pump comprising, a cylinder having a lower end for cooperation with the container, a piston movable inside the cylinder, a closure element arranged around a lower end of the piston, wherein the closure element comprises a bottom and a wall surrounding the lower end of the piston, wherein the bottom is adaptable between a rest position wherein a pressure difference over the bottom is lower than a predefined threshold and an indicator position when the pressure difference equals or exceeds the predefined threshold.

Claims

1. A manually operable pump for cooperation with a container to reduce pressure inside the container; the pump comprising: a cylinder having a lower end for cooperation with the container; a piston movable inside the cylinder; and a closure element arranged around a lower end of the piston, wherein the closure element comprises a bottom and a wall surrounding the lower end of the piston, wherein the bottom is adaptable between a rest position when a pressure difference over the bottom is lower than a predefined threshold and an indicator position when the pressure difference equals or exceeds the predefined threshold.

2. The pump according to claim 1, wherein the bottom is adaptable between the rest position and the indicator position to provide an indication to a user when a predetermined pressure difference between the container and the environment is reached.

3. The pump according to claim 1, wherein at least a part of the wall of the closure element is adaptable between a sealing position in which it provides for sealing between the piston and the cylinder and a free position allowing for a passage of air between the wall and the cylinder.

4. The pump according to claim 3, wherein the wall is in the sealing position when the piston moves upwardly with respect to the cylinder, and wherein the wall is in the free position when the piston moves downwardly with respect to the cylinder.

5. The pump according to claim 1, wherein the closure element is from a resilient material.

6. The pump according to claim 1, wherein, in the rest position, the bottom is in a concave position, and/or wherein in the indicator position, the bottom is in a convex position.

7. (canceled)

8. The pump according to claim 1, wherein a thickness of the bottom of the closure element is larger towards the walls than in a center of the bottom, and/or wherein the closure element is absent of predefined deformation lines.

9. (canceled)

10. The pump according to claim 1, wherein the wall of the closure element is provided with at least one wall connection element for engagement with a corresponding piston connection element.

11. The pump according to claim 10, wherein the wall connection element is provided as an inwardly protruding element, and wherein the piston connection element is configured as a recess, wherein the inwardly protruding wall connection element is configured to fit into the corresponding recess in an outer wall of the piston.

12. The pump according to claim 1, wherein the lower end of the piston is provided with an outwardly extending skirt, and/or wherein the skirt provides for a wall of the recess.

13. (canceled)

14. The pump according to claim 12, wherein a thickness of the wall connection element is larger than a distance between the skirt of the piston and an inner wall of the cylinder.

15. The pump according to claim 3, wherein the wall of the closure element comprises an outer flange that is configured to be adaptable between the sealing position and the free position.

16. (canceled)

17. The pump according to claim 1, wherein the pump is provided with at least one through hole, providing a fluid connection between an inside of the piston and an environment outside of the piston, and/or wherein the at least one through hole is provided at or near an upper end of the pump.

18. (canceled)

19. The pump according to claim 18, further comprising a sound deflector arranged inside of the piston to deflect and/or dampen and/or absorb sound waves generated by the bottom of the closure element; and/or wherein a user can partially or fully close the at least one through hole, so as to dampen sound waves generated by the bottom of the closure element and/or so as to receive such sound waves as a tactile stimulus.

20. The pump according to claim 1, wherein the cylinder is provided with at least one cooperating element at the lower end thereof, and/or wherein the cooperating element is adapted for cooperation with the container.

21. (canceled)

22. The pump according to claim 20, wherein the cooperating element is provided with a seat which seat is configured for cooperation with the closure element.

23. The pump according to claim 1, wherein the closure element is a single piece element, manufactured by injection moulding, compression moulding, or 3D-printing.

24. The pump according to claim 1, wherein a sudden adoption of the closure element from the rest position to the indicator position provides audible, visual, and/or haptic feedback to a user of the pump, and/or generates a sound, which provides for an audible feedback to the user indicating that the predefined pressure difference is reached.

25. (canceled)

26. The pump according to claim 1, wherein the piston has a hollow interior, such that sound waves can move from the closure element towards a head of the pump.

27. The pump according to claim 1, wherein the lower end of the cylinder is arranged for cooperation with a bottle and/or a stopper inserted in an opening of the container.

28. A set of the pump according to claim 1 and a vacuum stopper, wherein the vacuum stopper is provided with a valve and is mountable in an opening of the container, and/or multiple closure elements, each closure element having a different predetermined pressure difference threshold value.

29. (canceled)

Description

[0024] These and other aspects will be further elucidated with reference to the drawing comprising figures of exemplary embodiments. Corresponding elements are designated with corresponding reference signs. In the drawing shows:

[0025] FIG. 1 a cross-section of a pump according to the invention with the closure element in rest position;

[0026] FIG. 2 a cross-section of a pump according to the invention with the closure element in indicator position;

[0027] FIG. 3 a perspective exploded view of the pump of FIG. 1 having a through hole in the wall of the piston;

[0028] FIG. 4a a cross-section of the pump of FIG. 1 in engagement with a vacuum stopper;

[0029] FIG. 4b a detail of the closure element resting on the cooperating element, when the piston is in the lowest position;

[0030] FIG. 5a a cross-section of a lower end of the pump when the piston moves upward;

[0031] FIG. 5b a cross-section of a lower end of the pump when the piston moves downward;

[0032] FIG. 6 a cross-section of the lower end of the piston with the closure element in indicator position;

[0033] FIG. 7 a cross-section of the upper end of the piston showing the path of the sound waves;

[0034] FIG. 8a a side view of the closure element;

[0035] FIG. 8b a cross-section of the closure element

[0036] FIG. 9a a perspective view of the pump with an alternative head;

[0037] FIG. 9b a cross-section of a detail of the head of the pump of FIG. 9a

[0038] FIG. 9c the detail of FIG. 9b with an insert;

[0039] FIG. 9d the detail of 9b with a finger of a user;

[0040] FIGS. 10a, 10b, 10c and 10d the closure element in various positions;

[0041] FIG. 11 a configuration of the pump with a closure element for use as a blowing pump.

[0042] It is to be noted that the figures are given by way of exemplary examples and are not limiting to the disclosure. The drawings may not be to scale.

[0043] FIG. 1 shows a manually operable pump 1. The pump 1 comprises a cylinder 2 having a lower end 3 for cooperation with a container. Inside of the cylinder 2, there is a piston 4 provided. The piston 4 is movable upwardly and downwardly in the cylinder 2. The piston 4 has a lower end 5 and an upper end 6. Around the lower end 5, a closure element 7 is arranged. The closure element has a bottom 8 and a wall 9. The wall 9 surrounds the lower end 5 of the piston 4. The bottom 8 is adaptable between a first position, shown in FIG. 1, in which the pressure difference between the container and the environment outside the container, being the pressure difference over the bottom 8 between a chamber below the bottom 8 and an inside of the piston 4 above the bottom 8, is lower than a predefined threshold. When the pressure difference over the bottom 8 is equal to or exceeding the predefined threshold, the bottom 8 suddenly and abruptly adapts to a second position, the indicator position. This position is shown in FIG. 2. Since the bottom 8 of the closure element 7 only changes position when the predefined pressure difference over the bottom 8 is reached, an indication of the pressure inside of the container is given to the user.

[0044] Depending on the shape of the closure element 7, the pump 1 can be operated as a vacuum pump or can be operated as a pressure pump. In the embodiment shown in FIG. 1 and FIG. 2, the closure element 7 has a concave shape in rest position and a convex shape in the indicator position, the pump thus acting as a vacuum pump. Alternatively, the closure element 7 can have a convex shape in rest position and a concave shape in indicator position, the pump then acting as a pressure pump. The principle of the closure element 7 remains the same. As soon as a predetermined pressure difference between the container and the environment outside of the container is reached, under pressure or over pressure, the bottom 8 of the closure element 7 flips to the indicator position.

[0045] At the upper end 6 of the piston 4, a head 10 is provided to close off the piston 4 at the upper end 6. The head 10 can be provided in the form of a knob such that it easily fits into a hand of a user. The user manipulates the head 10 to operate the pump 1 and to move the piston 4 in the cylinder 2 up and down. The head 10 is here provided as an assembly comprising an insert 11 in the upper end 6 of the piston 4, that is closed of by a cap 12. A ring 13 firmly connects the insert 11 to the piston 4.

[0046] In the piston 4, at the upper end 6 thereof, at least one through hole 14 is provided. In this example, one through hole 14 is provided in the piston 4. Alternatively, for example, two through holes opposite each other may be provided. The one or more through holes 14 provide for a fluid connection between an inside 15 of the piston 4 and the environment 16 outside of the piston 4. Due to the sudden change of the bottom 8 from the rest position, in FIG. 1, to the indicator position in FIG. 2, when a predefined pressure difference over the bottom 8 is reached, a sound is generated. This sound can travel through the inside 15 of the piston 4 and through the at least one through hole 14 towards the environment. To improve the propagation of the sound towards the environment, a sound deflector 17 may be provided at the upper end 6 of the piston 4. In this example, the sound deflector 17 is formed as a part of the insert 11 of the head 10. Additionally, the sudden flip of the position of the bottom 8 may also induce vibrations in the wall of the piston 4 that may travel upwardly to the head 10, where they can be felt by a user holding the head 10, thus serving as haptic feedback to the user. The head 10 can be a knob that the user can hold to manipulate the piston 4 up and down in the cylinder 2. The at least one through hole 14 may be wholly or partially closable, e.g. by a sliding element or any other type of covering element. By partially closing the at least one through hole, the user can adapt the volume of the audible feedback. When the user entirely closes the at least one through hole, the audible feedback is blocked, and, possibly, only the haptic or tactile feedback, the vibrations felt by the user, may remain to give the user an indication that the predefined threshold is reached. For some users and/or in some environments, the haptic feedback may be sufficient, and the audible feedback may be closed.

[0047] The lower end 3 of the cylinder 2 is arranged for cooperation with a container, or, for cooperation with a stopper inserted in an opening of the container. In some examples, the cylinder 2 may directly cooperate with the container, in other examples, the cylinder 2 may cooperate with the stopper inserted in the container. The container can be e.g. a bottle, a stopper may then be inserted in a neck of the bottle, and the cylinder 2 of the pump 1 may then engage the stopper inserted in the opening of the container. To provide for an air-tight connection of the cylinder 2 with the container and/or with the stopper, the lower end 3 of the cylinder 2 can be provided with a soft edge, e.g. an elastic material that can be slightly compressed with engaging with the container and/or with the stopper. In this example, shown in FIG. 1 and FIG. 2, the lower end 3 of the cylinder 2 is provided with a cooperating element 18. The cooperating element 18 can for example be an element of a plastic material, such that, in engagement with the container and/or with the stopper an air-tight connection is obtained. The cylinder 2 has an upper end 31 against which the lower end 5 of the piston 4 abuts when in the most upward position. The upper end 31 is thereto provided with a shoulder 32 having an abutment surface 33, which abutment surface 33 is facing downwardly. The lower end 5 of the piston 4 is provided with a stop 51 that is arranged for abutting the abutment surface 33 when in the most upward position. When the stop 51 contacts the abutment surface 33 of the shoulder 32 of the cylinder 2, the piston 4 has reached an end of its stroke and can be moved downwardly. The shoulder 32 thus prevents the piston 4 from unintentionally being removed from the cylinder 2, and, provides for a stop surface as well.

[0048] FIG. 3 shows an exploded view of the pump 1, with the head 10 comprising the cap 12, the insert 11 and the ring 13. The cylinder 2 and the piston 4 are shown, with the closure element 7 connectable to the lower end of the piston 4. The cooperating element 18, that optionally can be provided to the lower end 3 of the cylinder 2, is also shown. Here, it can be seen that the closure element 7 is a single piece element with an upwardly extending wall 9 and a bottom 8.

[0049] FIG. 4a shows the vacuum pump 1 engaged to a stopper 19, that is mounted to a container 20. Here, a stopper 19 is provided as described in PCT application WO 2021/054825A1. However, any type of vacuum stopper that can be inserted in an opening of a container, can be provided. Although the coopering element 18 is adapted to cooperate with the stopper 19 as shown here, the vacuum pump 1 according to the invention is not limited to the use with such a stopper. The cooperating element 18 is here provided with a recess 182 in which a flange 191 of the stopper 19 fits. The stopper 19 has a valve 21 that can open and close. When a different stopper is used, a correspondingly adapted cooperating element 18 can be provided and can be connected to the lower end 3 of the cylinder 2. The cooperating element 18 is provided with an internally protruding rim 22 that engages with a groove 23 in the lower end 3 of the cylinder 2. By this rim-groove connection, the cooperating element 18 can relatively easily be connected and disconnected from the cylinder 2, and thus be replaced by a different cooperating element 18 that may be adapted for a different vacuum stopper. In the cooperating element 18, there is a bore 24 allowing air to pass through. In the configuration shown in FIG. 4a, when the pump 1 engages the stopper 19 that is mounted into an opening of the container 20, a chamber 25 is created between the closure element 7, the cylinder 2, and the stopper 19. When the valve 21 of the stopper 19 is open, the chamber 25 is in fluid connection with an interior of the container 20. The pressure difference over the bottom 8 of the closure element 7, meaning the pressure difference between the chamber 25 and the environment 16 that is in fluid connection with the inside of the piston, determines the change of the position of the bottom 8 of the closure element. When said pressure difference is below a predefined threshold, the bottom 8 remains in the rest position. When said pressure difference equals or exceeds the predefined threshold, the bottom 8 swaps to the indicator position. The pressure difference is an indication of the under pressure reached in the interior of the container 20.

[0050] In FIG. 4a it can be seen that the lower end 5 of the piston 4 is provided with a skirt 26 against which the bottom 8 of the closure element 7 rests in rest position. As such, the resilient bottom 8 can be supported in the rest position. The skirt 26 is shaped correspondingly to the shape of the closure element 7 in rest position. The lower end 5 of the piston 4 is further provided with connection element 27, here embodied as a circumferential groove, in which a corresponding wall connection element 28 can engage. The wall connection element 28 is here embodied as an inwardly protruding rim that engages in the piston connection element 27 formed as groove 27. Alternatively, a groove may be provided on the closure element 7 and a corresponding rim may be provided on the lower end 5 of the piston 4. The connection elements may be provided continuously in the circumference, or can be embodied as a discrete number of cooperating fingers and recesses, or hooks and grooves etc. Many variants of such connection elements can be envisaged.

[0051] Advantageously, the radial thickness t of the wall connection element 28 and the height h thereof, provide for a relatively stiff part of the wall 9 of the closure element 7. The free, i.e. uncompressed, height of the wall connection element 28 may, in an example, be somewhat larger than a height h of the corresponding piston connection element 27 to provide for a clamping engagement. For example, a relatively thick and stiff inwardly protruding rib can be obtained. Such inwardly protruding wall connection element can be sufficiently stiff that it deforms less than the rest of the closure element 7 due to the piston movement up and down inside of the cylinder 2. As such, the wall connection element 28 provides for a firm and reliable connection to the piston connection element 27, here the annular recess 27. The lower wall of the recess 27 is provided by the skirt 26. Between an outer edge of the skirt 26 and the inner wall 30 of the cylinder 2 a distance d is provided. The radial thickness t of the wall connection element 28 is preferably larger than the distance d between the skirt 26 and the wall 30 of the cylinder 2, to prevent the wall connection element 28 from slipping through the annular opening with distance d when deformed due to piston movement. As such, the wall connection element 28 provides for firm and reliable connection of the closure element 7 to the piston 4, even when elastically deformed due to the piston movement. Advantageously, the thickness t is larger than the distance d to prevent slipping through or falling down of the closure element.

[0052] The wall 9 of the closure element 7 is at least partially adjustable, between a sealing position in which the wall 9 engages with the cylinder 2, and a free position, in which the wall 9 is free from the cylinder 2, allowing air to pass through a passage between the cylinder 2 and the wall 9. In particular, the wall 9 is provided with an upwardly extending flange 29. Said flange 29 contacts an inner surface 30 of the cylinder 2 in the sealing position, thereby providing for a sealing engagement between the closure element 7 and the cylinder 2. In the free position, the flange 29 is moved somewhat inwardly to come loose from the inner cylinder surface 30 and to provide for a passage between the inner cylinder surface 30 and the closure element 7 to allow air to pass through. The single piece closure element 7 is sealing element and indicator element in one single component. This may facilitate manufacturing and/or assembly and/or maintenance.

[0053] The lower end cooperating element 18 is at an under side thereof provided with the recess 182 for engagement with a stopper. At the upper side of the lower end cooperating element 18, opposite the side that is configured for engagement with the stopper, the cooperating element 18 can be provided with a seat 181. The seat 181 is configured to receive the closure element 7, in particular the bottom 8 of the closure element 7. In the lowest position of the piston 4 within the cylinder 2, the bottom 8 of the closure element 7 rests onto the seat 181, as can be seen in FIG. 4b. The seat 181 is provided as a recess that corresponds with the size of the bottom 8 of the closure element 7. In particular an outer edge 81 of the bottom 8, while a center 82 of the bottom 8 is not in the same plane as the outer edge 81, abuts to the seat 181 when in the lowest position of the piston 4. As such, dead space in the piston can be minimalized, and the piston 4 can become more efficient because less dead space needs to be overcome when starting pumping.

[0054] The operation of the pump 1 and the closure element 7 is shown in FIG. 5a and FIG. 5b. In use, the pump 1 is mounted to the stopper 19, which is inserted to the container 20 to close off an opening of the container. The pressure in the container 20 can be reduced by extracting air out of the container 20. By moving the piston 4 up and down in the cylinder 2, air can be sucked out of the container 20. FIG. 5a shows the piston 4 in an upward movement, along the direction indicated with arrow A. When moving the piston 4 up with respect to the cylinder 2, the flange 29 of the wall 9 of the closure element 7 moves outwardly and contacts the inner surface 30 of the cylinder 2 thereby sealing any passage between the piston 4 and the cylinder 2. The flange 29 sealingly engages the inner wall 30 of the cylinder 2 thereby acting as a sealing element. As such, a separate sealing element can be obviated. Between the closure element 7, the inner wall 30 of the cylinder 2 and the stopper 19, the chamber 25 is provided.

[0055] When moving the piston 4 upwardly, the chamber 25 becomes larger and the pressure in the chamber 25 decreases. There is then a pressure difference over the closure element 7, with the pressure above the closure element, i.e. in the environment 16, larger than the pressure below the closure element 7, in the chamber 25. Due to this pressure difference, the flange 29 moves outwardly and provides for the sealing engagement with the inner wall 30 of the cylinder 2. Also, when the pressure in the chamber 25 decreases, the valve 21 of the stopper 19 opens and air is sucked out of the container 20 trough the bore 24 in the lower end cooperating element 18 into the chamber 25. In upward movement, when the valve 21 of the stopper 19 is open, the container 20 and the chamber 25 are fluidly connected and have substantially the same pressure. The flow of the air is indicated by arrows R. When the piston 4 has reached the upper end of the cylinder 2, and the stop 51 of the piston 4 contacts the shoulder 32 of the cylinder 2, the piston 4 has reached the end of its stroke. The user can then move the piston 4 down.

[0056] The downward movement of the piston 4 is shown in FIG. 5b. When moving the piston 4 downwardly, along the direction indicated by arrow B, the chamber 25 becomes smaller. Due to the decreasing volume of the chamber 25, the pressure difference over the closure element 7, between the environment 16 and the chamber 25, changes. The pressure in the chamber now becomes larger than the pressure of the environment 16, causing the flange 29 to move inwardly. Due to the flange 29 moved inwardly, a passage 34 between the flange 29 and the inner surface 30 of the cylinder 2 opens and allows air to pass through, indicated by arrows R in FIG. 5b. Also, due to the increasing pressure in the chamber 25, the valve 21 of the stopper 19 closes, preventing air to go back into the container 20. Air that has passed the passage 34 further flows upwardly towards the environment, and can pass through a passage between the piston 4 and the shoulder 32 of the cylinder 2, where there is no sealing engagement, but instead an open connection to the environment. As such, air that was extracted from the container 20 can be discharged to the environment 16, thereby reducing the pressure in the container 20.

[0057] When, in an upward movement of the piston 4, the pressure difference over the closure element 7, between the environment 16 above the closure element 7 and the container 20 below the closure element 7, reaches a certain predefined value, the bottom 8 of the closure element 7 suddenly and abruptly changes position towards the indicator position. The bottom 8 suddenly flips from one position, the rest position in which it has a concave shape, towards another position, the indicator position in which it has a convex shape. This sudden flipping of position of the bottom 8 of the closure element 7 generates a sound, which is visually indicated in FIG. 6. A sound in the sense of a POP is generated. The sound waves then travel upward in the piston 4 towards the upper end 6 of the piston 4. FIG. 7 shows how the sound travels to the environment 16 through the at least one through hole 14 in the piston 4. The sound deflector 17 that is arranged on the insert 11 of the piston head 10, aids in deflecting the sound waves towards the through hole 14. Here, the at least one through hole is provided in a wall 41 of the piston 4, alternatively, a through hole can be provided in the head 10, or in the cap 12 of the head 10. In the latter, no sound deflector is needed, as the sound waves then may travel straight ahead.

[0058] FIGS. 8a and 8b show the closure element 7. In the side view of FIG. 8a of the closure element, two recesses 35 are shown. These recesses 35 are distributed evenly over the circumference of the wall 9. Multiple recesses 35 may be provided. The recesses 35 facilitate air to flow from the chamber 25 to the passage 34 when the flange 29 is in the inward, free position. By providing these recesses the flow rate of air that can flow towards the passage 34 can become larger, thereby preventing a whistle noise that would occur when the flow rate of the air during downward movement of the piston 4 would be too small. The recess 35 here has a triangular shape, but can have any other shape.

[0059] The flange 29 has a beveled upper edge 36 provided with an outer surface 40 of the flange 29 with an angle with respect to the wall 9. The angle alpha between the wall 40 of the beveled upper edge 36 and the wall 9 can be between about 5 degrees to about 45 degrees. By providing this beveled edge 36, a circumferential line contact can be created between the beveled edge 36 and the inner wall 30 of the cylinder 2, when the flange 29 is in the sealing position. Such circumferential line contact provides for a more reliable sealing. Alternatively, a circumferential surface contact between the surface 40 and the inner wall 30 of the cylinder 2 can be provided, allowing for more distribution of the forces in the sealing position, and thus for less wear of the flange 29. In the cross-section of FIG. 8b the inwardly protruding wall connection element 28 is visible as the rim 28 or rib 28. The wall connection element 28 cooperates with the piston connection element 27 to firmly connect the closure element 7 to the lower end 5 of the piston 4. The corners of the wall connection element 28 are here beveled such that the rim more easily fits into the groove 27. Additionally, such beveled corners provide for a more easy removal of a mould when e.g. injection moulding.

[0060] The thickness profile of the bottom 8, being the variation in thickness of the bottom 8 in radial direction, as can be seen in the cross-section of FIG. 8b, provides for a thinner bottom 8 in the center of the bottom. By this radial variation in thickness of the bottom 8, the bottom 8 can flip from the rest position towards the indicator position without the need of a predefined deformation line. By varying the thickness profile and/or by varying the thickness and/or by varying the material properties, the predetermined threshold value of the pressure difference over the closure element 7, that defines at which pressure difference the bottom 8 flips from the rest position to the indicator position, can be adjusted. Optionally, the geometry of the bottom 8 can be varied as well to change the threshold value of the pressure difference. For example, the convex curvature of the bottom 8 can be made more flat, or more steep. As such, the threshold value for the pressure difference at which the bottom 8 flips from the rest position towards the indicator position, can be set while maintaining a smooth bottom profile without a predefined deformation line.

[0061] Thus, different closure elements 7, each having a different predetermined threshold value, can be made available. Since the closure element 7 can be easily connected to the lower end 5 of the piston 4 by a user by engaging the wall connection element 28 with the piston connection element 27, the user can relatively simply replace the closure element 7 by a different closure element, e.g. when a different pressure is needed in a container. To reach the closure element 7, the user can remove the lower end cooperating element 18 from the lower end 3 of the cylinder 2, by disengaging the rim 22 from the groove 23. The user can then reach the closure element 7 and remove it, and replace it by a different closure element 7. The user can then remount the lower end cooperating element 18. Optionally, the piston head 10 can be removed from the upper end 6 of the piston 4. Then, the piston 4 can be removed from the cylinder 2 via the lower end 3 of the cylinder 2, from which the cooperating element 18 is disengaged. When the piston 4 is removed, the user can also change the closure element 7.

[0062] The closure element 7 is a single piece, made from a single material, preferably by injection moulding. The material of the closure element 7 is preferably a thermoplastic polymer or a silicone rubber or any other type of resilient material that is elastically deformable, such as e.g. polyolefin. By varying the properties of the material and/or by varying the thickness profile of the bottom of the closure element, a different threshold value for the predefined pressure difference can be set. Advantageously, the material of the closure element 7 is a so-called self-lubricating, sweating, or oil bleeding silicone material, that during use, gradually releases a kind of lubricant, thereby providing for lubrication between the closure element 7 and the cylinder 2. After a certain period of use, the material may run dry, and the closure element 7 may need to be replaced. Alternatively, the closure element may be provided from liquid silicone rubber, this material is resistant against material creepage and retains its original molded shape over time. Also, this material is resistant to oil and resistant to wearing and tearing which can be beneficial when used in combination with a metal or metal edged container.

[0063] Replacement of the closure element 7, however, is simple, by removing the cooperating element 18, if present, and optionally removing the piston head 10 to remove the piston 4 from the cylinder 2. The thickness of the bottom 8 is largest at an outer radial edge 81, where the bottom 8 meets the wall 9 and is smallest at the center 82 of the bottom 8. The thickness of the bottom 8 gradually decreases from the outer radius to the center of the bottom 8, the decrease in thickness over the radius of the bottom 8 may be linear or non-linear, but remains smooth without a predefined deformation line.

[0064] FIGS. 9a and 9b show an alternative embodiment of the head 10 of the pump 1. Here, the piston 4 is absent of any through holes, the at least one through hole 14 being provided in the head 10. The head 10 comprises the cap 12 and the ring 13, there is no insert 11 anymore. Also, there is no sound deflector anymore. The sound now moves from the closure element 7 through the hollow interior 15 of the piston 4 towards the head 10, and can leave the inside 15 of the piston 4 via the through hole 14 in the head 10. The sound waves can propagate in axial direction of the piston 4 and can leave the piston 4 in axial direction as well. No sound deflection is required. The head 10 may be covered by a covering element for partially or wholly closing the through hole 14 in the head 10, to reduce or to dampen the sound propagated via the through hole 14. Alternatively, the insert 11 with the deflector 17 can be used in combination with the head 10 to prevent the sound from propagating to the through hole 14 in the cap 12. The head 10 comprises the cap 12 that is engaged to the piston 4 via corresponding screw thread 52. The cap 12 is provided with an inner screw thread which engages with an outer screw thread on the upper end 6 of the piston 4. Over the cap 12, the ring 13 is mounted. By providing the ring 13, the head 10 may obtain a more ergonomic grip. The cap 12 is provided with outwardly extending ribs 121 that may fit into corresponding grooves 131 of the ring 13. The ring 13 may then be mounted first over the piston 4, the cap 12 can be fitted to the ring 13, by fitting the ribs 121 in the corresponding grooves 131, and tightening the cap 12 via the screw thread 52 to the piston 4, the head 10 can be firmly connected to the piston 4. By loosening the cap 12 and the ring 13, the head 10 can be disassembled from the piston 4, e.g. for cleaning purposes. All components are dishwasher-safe. The through hole 14 is here provided in a V-shape, but can, evidently be provided in any other shape. Further, an indent 53 is provided at the lower end 5 of the piston 4 allowing the user to more easy remove the closure element 7 from the piston. For example, the user may grab more easy behind the flange 29 to remove the closure element 7 from the piston.

[0065] FIG. 9c shows the embodiment of FIG. 9b further comprising an insert 11 that is provided to the upper end 6 of the piston 4, in particular, the insert 11 here engages to the cap 12 of the head 10 and extends over the inner diameter of the inside 15 of the piston 4. The insert 11 can fully or partially block the through hole 14 to prevent the sound from propagating through the through hole 14 or to reduce the sound level through the through hole 14. The insert 11 can for example contain sound absorbing material to absorb partially or fully the sound generated by the flipping of the closure element 7 to the indicator position. FIG. 9d shows that a user can also partially or fully close the through hole 14, and thus can control the level of the sound coming through the through hole 14.

[0066] FIGS. 10a, 10b, 10c, 10d show the closure element in various elastically deformed positions. The closure element 7 is made from resilient material, such material is elastically deformable. Due to this resilience of, also the bottom 8 of, the closure element 7, the up-and-downward movement of the piston 4 in the cylinder 2 when pumping may cause some deformation of the bottom 8 of the closure element 7. Such elastic deformation may be elongation of the shape of the bottom 8 in rest position due to the pumping movement of the piston 4. It is however only when the predetermined pressure difference threshold is reached that the bottom 8 flips suddenly from the rest position to the indicator position. FIG. 10a shows the closure element 7 in the undeformed rest position. Here, the closure element 7 is configured for the pump as vacuum pump. FIG. 10b shows an elastic deformation of the bottom 8 that can occur during movement of the piston, as long as the pressure difference threshold has not yet been reached. FIG. 10c shows the indicator position, the position to which the bottom 8 suddenly flips when the pressure difference threshold is reached. FIG. 10d shows another example of an elastic deformation of the bottom 8 that can occur during movement of the piston, after the pressure difference threshold and thus the indicator position (FIG. 10c) has been reached. FIG. 10d shows a possible elongation of the bottom 8 of the closure element. All these deformations are elastic deformation, meaning that, after removal of the cause of the deformation, the closure element and its bottom, return to the undeformed rest position.

[0067] FIG. 11 shows an alternative embodiment of the pump 1. Here, the closure element 7 is connected upside down to the lower end of the piston 4 With the closure element 7 in such upside-down position, the pump 1 can function as a blowing pump. The closure element 7 may also, similar as for the embodiment of e.g. FIG. 1, suddenly flip to the indicator position when the pressure difference threshold is reached. In this respect, the functioning of the closure element 7 remains essentially the same when mounted in this position to the piston, and for reasons of conciseness this will not be repeated here. In case of a blowing pump the pressure difference is mirrored with respect to a vacuum pump, the pressure inside the container now becomes higher than the environmental pressure. In view of this pressure mirroring, the closure element is mirrored as well, while the functioning thereof otherwise remains the same.

[0068] Aspects of the disclosure are explained using the drawings. It is understood that many aspects can be embodied differently, e.g. when a different stopper is used, the cooperating element is adapted accordingly. Also, the connection elements between the closure element and the piston can be embodied differently and alternatively. Also, many variants of the piston head 10 are possible without removing of the scope of the invention as claimed.

[0069] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the claims and disclosure may include embodiments having combinations of all or some of the features described. It may be understood that the embodiments shown have the same or similar components, apart from where they are described as being different.

[0070] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word comprising does not exclude the presence of other features or steps than those listed in a claim. Furthermore, the words a and an shall not be construed as limited to only one, but instead are used to mean at least one, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage. Many variants will be apparent to the person skilled in the art. All variants are understood to be comprised within the scope defined in the following claims.

LIST OF REFERENCE SIGNS

[0071] 1 vacuum pump [0072] 2 cylinder [0073] 3 lower end of cylinder [0074] 4 piston [0075] 5 lower end of piston [0076] 6 upper end of piston [0077] 7 closure element [0078] 8 bottom [0079] 9 wall [0080] 10 head of piston [0081] 11 insert of head [0082] 12 cap of head [0083] 13 ring of head [0084] 14 through hole [0085] 15 inside of piston [0086] 16 environment [0087] 17 sound deflector [0088] 18 lower end cooperating element [0089] 19 stopper [0090] 20 container [0091] 21 valve [0092] 22 rim [0093] 23 groove [0094] 24 bore [0095] 25 chamber [0096] 26 skirt [0097] 27 piston cooperating element [0098] 28 wall cooperating element [0099] 29 flange [0100] 30 inner surface of cylinder [0101] 31 upper end of cylinder [0102] 32 shoulder [0103] 33 abutment surface [0104] 34 passage [0105] 35 recess [0106] 36 beveled edge [0107] 40 outer surface [0108] 41 wall of piston [0109] 51 stop [0110] 52 screw thread [0111] 53 recessed region in lower end piston [0112] 81 outer edge of bottom [0113] 82 center of bottom [0114] 121 ribs on cap 12 [0115] 131 grooves in ring 13 [0116] 181 seat of cooperating element [0117] 182 recess of cooperating element [0118] 191 flange of stopper [0119] Alpha angle of beveled edge of closure element [0120] d distance between skirt 26 and cylinder wall 30 [0121] A upward movement [0122] B downward movement [0123] h height of wall cooperating element [0124] R direction of flowing air [0125] t thickness of wall cooperating element