Filter and a method for checking the suitability of a filter element

Abstract

A filter element is provided and includes a filter medium having an axial channel, end plates each sealingly covering one axial end of the filter medium, one end plate having an opening in fluid communication with the channel, a hole arranged on the liquid path, not on the filter medium, and a closing member which is arranged in the hole and which is configured: to prevent liquid from flowing through the hole when the liquid pressure upstream the closing member is below a predetermined threshold to open at the threshold, to allow liquid to flow through the hole, and, after it has been opened, to remain open. A method is provided for checking the suitability of a filter element, at first use after a filter element change. The method includes monitoring the liquid pressure at a point of the liquid circuit located outside of and near a port of a filter housing receiving the filter element, when an electrical pump of the liquid circuit is restarted for the first time, comparing the evolution of the monitored liquid pressure over time with a predetermined evolution over time of the liquid pressure at the point for a new reference filter element.

Claims

1. A filter element intended to be mounted in a liquid filter arrangement comprising: a filter medium having a general annular shape around a central axis and forming a central channel extending substantially axially; a first end plate and a second end plate, each end plate covering one axial end of the filter medium and being sealingly mounted on the axial end, at least one of the first end plate and the second end plate having an opening in fluid communication with the central channel; at least one closing member, the closing member being configured when the filter element is mounted into the liquid filter arrangement: to remain closed when a liquid pressure that applies on the closing member is below a predetermined threshold pressure in order to prevent a liquid flow through a flow path of the liquid filter arrangement, the flow path being formed through at least the filter medium, to open only once when the liquid pressure that applies on the closing member reaches the predetermined threshold pressure in order to allow a liquid flow through the flow path, and after the closing member has been opened, to remain open, even if the liquid pressure that applies on the closing member drops below the predetermined threshold pressure.

2. The filter element according to claim 1, wherein the closing member is arranged into a hole that is part of the filter element.

3. The filter element according to claim 2, wherein the hole is arranged in the flow path.

4. The filter element according to claim 2, wherein the hole equipped with the closing member is arranged on the first end plate or the second end plate of the filter element.

5. The filter element according to claim 2, wherein the hole equipped with the closing member forms an inlet for the liquid to be filtered.

6. The filter element according to claim 2, wherein the hole equipped with the closing member is located on the first end plate or the second end plate, outside the filter medium.

7. The filter element according to claim 6, wherein the one of the first end plate and the second end plate on which is located the hole equipped with the closing member comprises a sealing element on its outside periphery, for providing sealing with an inner face of a peripheral wall of a filter housing intended to receive the filter element.

8. The filter element according to claim 2, wherein the hole equipped with the closing member and the opening in fluid communication with the central channel are distinct and are both arranged on the first end plate or the second end plate.

9. The filter element according to claim 2, wherein the hole equipped with the closing member is formed by the opening in fluid communication with the central channel.

10. The filter element according to claim 1, wherein the closing member comprises a membrane designed to break when the liquid pressure on one side of the membrane reaches the predetermined threshold pressure.

11. The filter element according to claim 1, wherein the closing member comprises a valve including a first element and a second element movable with respect to the first element from a closed position to an open position, the second element being in the closed position before the first use of the filter element and until the liquid pressure reaches the predetermined threshold pressure, and the second element being configured to move towards the open position when the liquid pressure reaches the predetermined threshold pressure.

12. The filter element according to claim 11, wherein the motion of the second element from the closed position to the open position is irreversible.

13. The filter element according to claim 11, wherein the valve further comprises means for maintaining the second element in the open position with respect to the first element.

14. The filter element according to claim 13, wherein the second element is a sealing ball and means for maintaining the sealing ball in the open position with respect to the first element, are realized by flexible or deformable legs or by a flexible or deformable collar which are or is designed to authorize motion of the sealing ball from the closed position to the open position and to prevent motion of the sealing ball from the open position to the closed position.

15. The filter element according to claim 14, wherein the first element is a valve body comprising an inlet and an outlet which are in fluid communication through a liquid passage formed in the valve body when the sealing ball is in the open position and in that the valve comprises, arranged in the valve body, a spring urging the sealing ball towards the closed position.

16. The liquid filter arrangement comprising: a filter housing comprising a bottom wall, a peripheral wall, and an open axial end opposite the bottom wall; a filter cover removably secured to the filter housing at the open axial end and defining with the filter housing a filter chamber; a filter element according to claim 1 that is mounted in the filter chamber; an inlet and an outlet being arranged in the filter housing and/or in the filter cover for the liquid to be filtered and, respectively for the filtered liquid, one of the inlet and the outlet being in fluid communication with the opening in fluid communication with the central channel; the flow path being formed by at least the inlet, a zone of the filter chamber located upstream from the filter medium, the filter medium, the central channel, the opening and the outlet.

17. An engine arrangement comprising an internal combustion engine and a liquid circuit for supplying liquid to the engine, the liquid circuit comprising: an electrical pump; the liquid filter arrangement according to claim 16, located downstream from the pump; a pressure sensor located inside or outside the filter chamber designed to measure pressure data; an electronic control unit designed to receive the pressure data measured by the pressure sensor, and to control the electrical pump.

18. A vehicle comprising the engine arrangement according to claim 17.

19. A set of filter elements according to claim 1, comprising: at least one filter element of a first filter element category, the or each filter element of the first filter element category being equipped with a closing member of a first kind designed to open at a first predetermined pressure threshold; at least one filter element of a second filter element category, the or each filter element of the second filter element category being equipped with a closing member of a second kind designed to open at a second predetermined pressure threshold different from the first predetermined pressure threshold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

(2) In the drawings:

(3) FIG. 1 is a schematic view of an engine arrangement according to the invention;

(4) FIG. 2a-2c are graphs showing the evolution of liquid pressure over time, for three filter elements of various categories;

(5) FIG. 3a-3b are graphs showing the evolution of liquid pressure over time, respectively for a liquid filter arrangement receiving a new reference filter element and for a liquid filter arrangement receiving no filter element;

(6) FIG. 4a-4b are graphs showing the evolution of liquid pressure over time, respectively for a new reference filter element and for an unsuitable filter element;

(7) FIG. 5 shows a detail of a liquid circuit including a liquid filter arrangement according to an embodiment of the invention, comprising a filter element equipped with a closing member, said closing member being in a closed state;

(8) FIGS. 6 and 7 show the liquid filter arrangement of FIG. 5 respectively when the closing member is being opened, and when the closing member is in the open state;

(9) FIG. 8 is a graph showing the evolution of the liquid pressure P1 over time, at a point located upstream from the closing member, as shown in FIG. 5, for various categories of filter elements;

(10) FIG. 9 is a graph showing the evolution of the liquid pressure P2 over time, at a point located downstream from the closing member, as shown in FIG. 5, for various categories of filter elements;

(11) FIGS. 10 and 11 show a first embodiment of a closing member, respectively before it is opened and after it has been opened; cracking membrane

(12) FIG. 12-15 show a second embodiment of a closing member, respectively before it is opened, during its opening, and after it has been opened.

DETAILED DESCRIPTION

(13) FIG. 1 shows an engine arrangement 1 comprising an internal combustion engine 2 and a liquid circuit 3 for supplying liquid to the engine 2.

(14) The liquid circuit 3 comprises a liquid tank 4 and a pipe 5 carrying liquid to the engine 2. On the pipe 5 is located an electrical pump 6, which can be an electrical low pressure pump and a liquid filter arrangement 10 located downstream from the electrical pump 6. An additional liquid filter arrangement 7 may be provided between the liquid tank 4 and the electrical pump 6.

(15) The liquid circuit 3 further comprises a pressure sensor 8 located outside the liquid filter arrangement 10. In the embodiment illustrated in FIG. 1 the pressure sensor 8 is located downstream from the liquid filter arrangement 10. However, other embodiments could be envisaged. Indeed, in different other embodiments, the pressure sensor can be located upstream the liquid filter arrangement and/or inside the liquid filter arrangement 10.

(16) The liquid circuit 3 further comprises an electronic control unit 9 designed to receive the pressure data measured by the pressure sensor 8 and to control the electrical pump 6.

(17) As shown in FIGS. 5-7, the liquid filter arrangement 10 comprises a filter housing 14 and a filter cover 15. The filter housing 14 and the filter cover 15 define a filter chamber 13. The filter housing 14, which is generally cylindrical, has an axis 16 and comprises a bottom wall 17, a peripheral wall 18, and an open axial end 19 opposite the bottom wall 17. The filter cover 15 is removably secured to the filter housing 14 at its open axial end 19. For example, the filter cover 15 comprises a disc-like plate and a skirt provided with an external thread for cooperation with an internal thread of the peripheral wall 18 of the housing 14. Two ports 11, 12 are arranged in the liquid filter arrangement, for instance, in the filter housing 14, one port being an inlet for the liquid to be filtered, the other one being an outlet for the filtered liquid. A portion of the pipe 5 is sealingly mounted in fluid communication with each of the ports 11, 12 for carrying the liquid to be filtered/once filtered.

(18) The liquid filter arrangement 10 also comprises a filter element 20 mounted in the filter chamber 13, substantially coaxially. The filter element 20 comprises a filter medium 21 forming a channel 22 extending along a central axis X and having a general annular cross-section around the central axis X. The filter medium 21 can be made of a sheet of cellulosic material or synthetic material folded so as to have, in cross section, the shape of a star having a plurality of branches. A rigid perforated central lube (not shown) provided with holes can be arranged in the channel 22 to prevent the filter medium 21 from flattening due to the liquid flow through it.

(19) The filter element 20 further comprises a first and a second end plates 25, 26, each end plate covering one axial end of the filter medium 21 and being sealingly mounted on said axial end. The first end plate 25 has an opening 27 in fluid communication with the channel 22. Typically, the opening 27 can be coaxial with the channel 22. When the filter element 20 is mounted in the filter chamber 13, the opening 27 is further in fluid communication with one of the inlet 11 and outlet 12 of the filter housing 14. In the embodiment of FIG. 5, the opening 27 is in fluid communication with the outlet 12.

(20) In use, a liquid to be filtered flows from the inlet 11 of the filter housing 14 through the filter medium 21, for example from the outside of the filter medium 21 towards the channel 22, and then out of the filter element 20 through the opening 27, and ultimately out of the liquid filter arrangement 10 through the outlet 12. Alternatively, the liquid to be filtered can flow reversely, i.e. from the channel 22 towards the outside of the filter medium 21.

(21) As the end plates 25, 26 are sealingly mounted on the filter medium 21, the inside and the outside of the filter medium 21 are not in fluid communication, except through the filter medium 21.

(22) When the filter medium 21 has become clogged, the filter element 20 is removed from the filter housing 14 during a maintenance operation and a new filter element 20 is inserted in the filter housing 14.

(23) It is of paramount importance that the inserted filter element 20 be appropriate, i.e. have the required properties for its intended use.

(24) The filter element 20 is chosen among a set of filter elements which pertain to various categories depending in particular on its size, on its capacity and/or on its efficiency which may depend on the filter medium constituent material, on the number of folds in the filter medium 21, etc . . . .

(25) It is also of paramount importance to ensure that a filter element 20 has been inserted in the filter housing 14, and that this filter element, in addition to pertaining to the appropriate category, has not been altered (i.e. has no manufacturing defect, is not at least partially clogged, has not been damaged, etc.).

(26) The invention provides a method for checking the suitability of a filter element 20 received in the filter housing 14 of the liquid filter arrangement 10, after a filter element change.

(27) The method is carried out at first use of the liquid filter arrangement 10 after a filter element 20 change, when the electrical pump 6 is restarted for the first time. The liquid pressure at a point A of the liquid circuit 3 located near a port of the filter housing 14, inside or outside the filter housing 14, is measured and monitored over time, by the pressure sensor 8 and the electronic control unit 9.

(28) A pump 6 of the electrical type is advantageously used in the method according to the invention because it can be operated regardless the operating state of the engine and regardless the engine speed.

(29) Moreover, the evolution of said monitored liquid pressure overtime is compared with a predetermined evolution over time of the liquid pressure at said point A for a new reference filter element, at first use of the new reference filtering filter element after a filter element change, when the electrical pump 6 is restarted for the first time. Indeed, as shown in FIGS. 2a-2c, the graph showing the evolution of liquid pressure over time, at a predetermined point of the liquid circuit 3, can be predetermined for a new reference filter element of a given filter element category, i.e. a filter element which has never been used, which has no defects, and which has predetermined characteristics (size, capacity, efficiency, etc . . . ).

(30) As shown in FIGS. 2a-2c, the typical pressure evolution from the pump first restart at t0 is a pressure increase, for example substantially linearly, until the pressure reaches the normal operating pressure PN. Moreover, the time for build-up pressure from the pump restart to the normal operating pressure depends on the filter element type. More specifically, when point A is located downstream from the filter element 10, the time for build-up pressure Δt is Δt1 for a filter element 20 having a small size, Δt2>Δt1 for a filter element 20 having a medium size, and Δt3>Δt2 for a filter element 20 having a large size.

(31) As a consequence, comparing the pressure evolution of the filter element 20 under test with the pressure evolution of a new reference filter element makes it possible to detect:

(32) if a filter element is present;

(33) if the filter element under test is of the appropriate type (size, capacity, efficiency . . . );

(34) if the filter element under test is new and intact.

(35) For example, if the pressure evolution over time of a new reference filter element is the one shown in FIG. 3a, and if the pressure evolution of the filter element under test is the one shown in FIG. 3b—i.e. the time to build-up pressure Δtb from the pump restart t0 to the normal operating pressure PN is lower than a reference time to build up pressure Δta—then the method according to the invention enables a user to know the filter element which has been inserted in the filter housing is unsuitable. In this case, the filter element may have a smaller capacity, or may even be absent.

(36) Another example is shown in FIGS. 4a and 4b. If the pressure evolution over time of a new reference filter element is the one shown in FIG. 4a, and if the pressure evolution of the filter element under test is the one shown in FIG. 4b—i.e. the time to build-up pressure Δtb from the pump restart t0 to the normal operating pressure PN is higher than a reference time time to build up pressure Δta—then the method according to the invention enables a user to know the filter element which has been inserted in the filter housing is unsuitable. In this case, the filter element may have a higher capacity.

(37) The method as described above can be carried out with a filter element as previously described.

(38) The method may comprise comparing other parameters on the pressure evolution graph.

(39) For example, the method can comprise using a specific filter element 20, as illustrated in FIGS. 5-7. Such a filter element includes a closing member 31. The closing member 31 is configured to prevent liquid from flowing through a flow path of the liquid filter arrangement 10 when the liquid pressure upstream the closing member 31 is below a predetermined threshold Pth. The closing member 31 is then in a closed state, as illustrated in FIG. 5. The closing member 31 is in this closed stale before its first use, and during its first use until said pressure reaches the predetermined threshold Pth.

(40) The flow path can be formed by at least the inlet 11, the dirty side of the filter chamber 13 that is to say the zone of the filter chamber that is located upstream from the filter medium 21, the central channel 22, the opening 27 and the outlet 12.

(41) Besides, when the liquid pressure upstream the closing member 31 reaches the predetermined threshold Pth, the closing member 31 is also configured to open, as illustrated in FIG. 6, and therefore allows liquid to flow through said flow path, as illustrated in FIG. 7.

(42) Finally, the closing member 31 remains open after it has been opened even if the liquid pressure that applies on the closing member 31 drops below said predetermined threshold pressure Pth.

(43) The filter element can also include a hole 30 that is arranged in the flow path. In the illustrated embodiment, the hole 30 is preferably equipped with the closing member 31 and is arranged on the first end plate 25, outside the filter medium 21. Furthermore, the first end plate 25 may comprise a sealing element 32 on its periphery, for providing sealing with the inner face of the peripheral wall 18 of the housing 14. In this exemplary embodiment, the hole 30 forms an inlet for the liquid to be filtered.

(44) Other implementation could however be envisaged, provided the hole 30 is arranged on the flow path of the liquid inside the filter housing 14. The hole 30 can be, for instance, arranged on the second end plate 26 of the filter element 20.

(45) FIGS. 8 and 9 show the typical pressure evolution over time, for new reference filter elements of two different filter element categories. A first new reference filter element that belongs to a first filter element category and that is equipped with a closing member 31 of a first kind that is designed to open at a first predetermined pressure threshold Pth1. A second new reference filter element that belongs to a second filter element category and that is equipped with a closing member 31 of a second kind that is designed to open at a second predetermined pressure threshold Pth2.

(46) FIG. 8 shows the evolution of pressure P1, upstream from the closing member 31, for instance, at a point A′ between the liquid filter arrangement 10 and the electrical pump 6 (see FIG. 1). FIG. 9 shows the evolution of pressure P2, downstream from the closing member 31, for instance, a point A (see FIG. 1) downstream from the liquid filter arrangement 10.

(47) The typical evolution of P1 from the pump first restart at t0 is a pressure increase, until the pressure reaches the predetermined threshold Pth causing the closing member 31 to open. The pressure peak Pth is obtained at time t, and then P1 decreases and then returns the normal operating pressure PN. Pressure P1 then remains substantially constant.

(48) The parameters of the pressure peak, in particular the values of Pth and t, depend on the filter element type, and among other characteristics on the kind of the closing member 31.

(49) FIG. 8 shows two graphs for two different kinds of closing members 31, leading to two different pressure peaks, namely: t1, Pth1; and t2, Pth2. FIG. 8 also shows a graph G obtained with an altered filter element, i.e. for example a filter element having an open closing member. It clearly appears that a used filter element can be easily detected by this method, as graph G is devoid of any pressure peak. This method further makes it possible to know if the filter element under test is the appropriate one, by detecting a pressure peak and comparing at least one parameter Pth or t of the detected pressure peak with at least reference value t1, Pth1; t2 or Pth2. The reference value preferably corresponds to said parameter Pth, t of said detected pressure peak wherein said parameter is determined for a reference pressure peak occurring with a new reference filter element equipped with a closing member. For instance, if for a given vehicle the suitable filter element category is determined as being the first one and if said parameter of the detected pressure peak is, for instance, the maximum pressure value Pth, said reference value will be the maximum pressure value Pth1 of the pressure peak that is reached with the first new reference filter element. If Pth matches or corresponds to Pth1 that means than the tested filter element belongs to the suitable filter element category, i.e. the first filter element category.

(50) By comparison with a new filter element that doesn't use a closing member 31, a filter element equipped with the closing member 31 according to the invention, will also delay at a first restart of the pump after filter element change the time it to build up pressure from the pump restart t0 to the normal operating pressure PN. Such as represented on FIGS. 8 and 9, each different pressure peak Pth1, Pth2 will also affect differently Δt1, Δt2 the time Δt to build up pressure from the pump restart t0 to the normal operating pressure PN.

(51) FIG. 9 also shows two graphs for two different lands of closing members 31, resulting from two different pressure peaks, namely: t1, Pth1; and t2, Pth2. FIG. 9 also shows a graph G obtained with an altered filter element, i.e. for example a filter element having an open closing member. As can be seen on FIG. 9 the pressure peaks can be difficult to detect when pressure is monitored downstream from the closing member 31. However it clearly appears that a used filter element can be easily detected by this method. This method further makes it possible to know if the filter element under test is the appropriate one, by comparing the mesured time Δt to build up pressure from the pump restart t0 to the normal operating pressure PN, with a reference time Δt1, Δt2 to build-up pressure from the pump restart to the normal operating pressure for a new reference filter element. Δt1 is a reference time for the first filter element category and Δt2 is a reference time for the second filter element category. The time Δt1, Δt2 are sufficiently different to allow identifying if the filter element belongs to the suitable filter element category. For instance, if for a given vehicle the suitable filter element category is determined as being the first one and if the measured time Δt, doesn't match or doesn't correspond to the reference time Δt1 that means that the filter element that has been inserted in the filter housing 14 doesn't belong to the suitable filter element category, i.e. the first filter element category.

(52) Checking the suitability of a filter element by the detection of a pressure peak is particularly reliable.

(53) A method according to the invention can also be carry out to identify, among different filer element categories, to which filter element category a new filter element 20 belongs and to adjust the maintenance interval between two successive maintenance operations depending on which filter element category the new filter element is identified to belong.

(54) By maintenance operation it is understood in the present description an operation that comprises the replacement of a used filter element by a new one.

(55) To this aim a specific method according to the invention can comprise the following steps:

(56) providing, in a step a, a set of filter elements 20 comprising:

(57) at least one filter element of a first filter element category, each filter element of said first filter element category being equipped with a closing member 31 of a first kind designed to open at a first predetermined pressure threshold Pth1,

(58) at least one filter element of a second filter element category, the or each filter element of said second filter element category being equipped with a closing member 31 of a second kind designed to open at a second predetermined pressure threshold Pth2 different from the first predetermined pressure threshold Pth1,

(59) receiving, in a step b, in the filter chamber 13 a new filter element 20 belonging to said first filter element category or to said second filter element category;

(60) monitoring, in a step c1, the liquid pressure at a point of the liquid circuit located near an inlet 11 or an outlet port 12 of the liquid filter arrangement 10, inside or outside filter chamber 13, when the electrical pump 6 is restarted for the first time after having received in the filter chamber 13 the new filter element 20,

(61) comparing, in a step d and when the electrical pump 6 is restarted for the first time, at least one parameter Pth, t and or Δt of said liquid pressure monitored over time with reference values Pth1, t1, Δt1, Pth2, t2, and/or Δt2 for said first and second filter element categories,

(62) depending on the result of the comparison performed in step d, identifying, in a step e, to which filter element category belongs the new filter element.

(63) For instance, if said parameter (Pth, t and/or Δt) matches with reference value determined for said first filter element category, it is identified that the new filter element belongs to the first filter element category.

(64) Although the method described above mentions in step a two filter element categories, the method is not limited to only two filter element categories. More than two filter element categories can be used in the above method.

(65) Said parameter Pth, t, Δt can be the measured time Δt to build-up pressure from the pump restart 10 to the normal operating pressure PN when the electrical pump 6 is restarted for the first time after filter element change and reference values are reference time Δt1, Δt2 to build-up pressure, at said point A, A′, from the pump restart t0 to the normal operating pressure PN for a new reference filter element of each filter element category.

(66) For instance, if the measured time Δt matches or corresponds to the reference time Δt1, determined for said first filter element category, it is identified that the new filter element belongs to the first filter element category.

(67) Preferably, the method further comprises a step c2 consisting in or comprising detecting, during the evolution of the liquid pressure monitored over time according to step c1, a pressure peak before the monitored liquid pressure drops and returns to the normal operating pressure PN and in that the step d consists, preferably, in or comprises comparing at least one parameter Pth, t of said detected pressure peak with reference values (Pth1, t1, Pth2, t2) for said first and second filter element categories.

(68) Preferably, the reference values correspond to said parameter Pth, t of said detected pressure peak wherein said parameter is determined for reference pressure peaks occurring with a new reference filter of each filter element category.

(69) Said parameter can be the pressure value Pth measured at the pressure peak. Preferably, said references values are the first predetermined pressure threshold Pth1 and the second predetermined pressure threshold Pth2 predetermined for each filter element category. In a variant, said parameter can be the time t between the pump restart t0 and the pressure peak.

(70) Preferably, in the set of filter elements previously described, filter elements belonging to different filter element categories have different filtering capacities and/or efficiencies and for each filter element category it is predetermined a specific maintenance interval that is different from one filter element category to another.

(71) Advantageously, in a further step f, following step e, it is determined, depending on which filter element category the new filter element 20 belongs, a maintenance interval, a time before the next maintenance operation or a distance that the vehicle can drive before the next maintenance operation.

(72) The maintenance interval, the time before the next maintenance operation or the distance that the vehicle can drive before the next maintenance operation can be displayed to user as a recommendation.

(73) According to an embodiment, the closing member 31 can comprise a membrane 33 which is initially intact, as shown in FIG. 10, and which is designed to break, or burst, when the pressure on one side of the membrane 33 reaches a threshold Pth. Depending on the constituent material of the membrane 33, on its thickness, or other parameters, the value of the threshold Pth can be different.

(74) According to another embodiment, the closing member 31 can comprise a valve 40, as shown in FIGS. 12-15. The valve may include a first element 41 and a second element 42 movable with respect to the first element 41 from a closed position to an open position. The second element 42 is in the closed position before the first use of the filter element 20 (FIG. 12). When the filter element 20 used, that is to say when the electrical pump 6 is energized, the second element 42 may remain in the closed position until the pressure reaches a threshold Pth. When the threshold pressure is reached, it can progressively move apart from the first element 41 (FIGS. 13 and 14) towards its open position, (FIG. 15). The second element 42 then remains in the open position (FIG. 15) with respect to the first element 41. Means can be provided to maintain the second element 42 in its open position. Therefore, the motion of the second element 42 from the closed position to the open position is irreversible. Because the valve 40 opens only once, the valve 40 is also called in the present application as a single opening valve.

(75) Such as represented, for instance, on FIG. 12, the second element 42 can be a sealing ball and means 46 for maintaining the sealing ball 42 in the open position with respect to the first element 41 can be, for instance, realized by flexible or deformable legs which are designed to authorize motion of the sealing ball 42 from the closed position to the open position and to prevent motion of the sealing ball 42 from the open position to the closed position.

(76) In a variant, means 46 for maintaining the the sealing ball 42 in the open position with respect to the first element 41 can be realized by a flexible or deformable collar designed to authorize motion of the sealing ball from the closed position to the open position and to prevent motion of the sealing ball from the open position to the closed position.

(77) The first element 41 can be realized by a valve body comprising an inlet 43 and an outlet 44 which are in liquid communication through a liquid passage 45 (see FIG. 15) formed into the the valve body 41 when the sealing ball 42 is in the open position. The valve preferably comprises, arranged in the valve body 41, a spring 47 urging the sealing ball 42 towards the closed position.

(78) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.