This application claims priority of German patent application no. 10 2022 120 289.5, filed Aug. 11, 2022, and European patent application no. 23 183 539.8, filed Jul. 5, 2023, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a butterfly valve assembly that can be used for example for a gas flow in a fuel cell system, in particular in a vehicle, for the purposes of providing electrical energy.
In such fuel cell systems, depending on the operating state, it is necessary to conduct different gas flows through or past the anode region, and through or past the cathode region, of a fuel cell or of a fuel cell stack. Here, stringent demands are placed on the leak-tightness of butterfly valve assemblies used to regulate such gas flows, in order to ensure, in particular in operating states in which a particular gas flow should not be conducted through a fuel cell or should not be conducted past a fuel cell, that leakage flows can be ruled out and substantially no gas can escape to the surroundings.
It is an object of the present disclosure to provide a butterfly valve assembly, in particular for a gas flow in a fuel cell system, in particular in a vehicle, which butterfly valve assembly can substantially prevent gas leakage while being of structurally simple configuration.
This object is, for example, achieved according to the disclosure via a butterfly valve assembly, in particular for a gas flow in a fuel cell system, in particular in a vehicle, including a butterfly valve housing which provides a gas flow channel, a butterfly valve which is adjustable in the butterfly valve housing between a closed position, substantially preventing a gas flow through the gas flow channel, and at least one open position, opening up the gas flow channel for a passage of flow, and which has a disk-shaped butterfly valve element supported on a pivot shaft which is rotatable about a pivot shaft axis, the pivot shaft having a first pivot shaft end portion, which is provided for coupling to a pivot shaft drive and which in a first bearing region is supported rotatably about the pivot shaft axis on the butterfly valve housing, and a second pivot shaft end portion, which in a second bearing region is supported rotatably about the pivot shaft axis on the butterfly valve housing, at least one bearing region out of the first bearing region and second bearing region including a bearing unit, which rotatably supports the pivot shaft, and at least one sealing element, which is subjected to axial load by the bearing unit and which lies against an outer circumferential surface of the pivot shaft.
Through the provision of the at least one sealing element that lies against the outer circumferential surface of the pivot shaft, it is ensured that, even if bearing play arises in the region of the at least one bearing unit, tight closure of the butterfly valve assembly that prevents an escape of gas is achieved.
Since the first pivot shaft end portion of the pivot shaft has to be led through the associated first bearing region in order to enable coupling to the pivot shaft drive, it is particularly conducive to gas-tight closure if the at least one bearing region is the first bearing region. In the second bearing region, in which the pivot shaft does not need to be led with its second pivot shaft axis through the bearing region or out of the bearing region, a gas-tight closure can be implemented by other measures, for example complete encapsulation of the second pivot shaft end portion via a bearing bushing.
To achieve a completely gas-tight connection of the at least one sealing element to the pivot shaft over the entire circumference of the pivot shaft, it is proposed that the at least one sealing element annularly surrounds the pivot shaft axis, and/or that the bearing unit annularly surrounds the pivot shaft axis.
In order to be able to firstly ensure stable positioning of the sealing element in the structural material of the bearing unit, and secondly ensure interaction with the pivot shaft that leads to adequate sealing, the at least one sealing element may include a holding portion, which is subjected to axial load by the bearing unit, and a sealing portion, which lies against the pivot shaft.
Here, in order to obtain an axially compact structure, the holding portion may extend substantially radially, and the sealing portion may extend radially inward from the holding portion toward the pivot shaft. Here, the at least one sealing element is thus substantially in the shape of an annular disk.
For defined axial clamping of the at least one sealing element, the bearing unit may include at least one bearing ring, and the holding portion of the at least one sealing element may be held between the at least one bearing ring and a base of a bearing bushing of the at least one bearing region and/or between the at least one bearing ring and the butterfly valve housing.
In order to be able to provide areal support for the at least one sealing element, it is proposed that, in its region which supports the at least one sealing element, the base of the bearing bushing, and/or the butterfly valve housing, is oriented substantially orthogonally with respect to the pivot shaft axis and is substantially planar.
In order to be able to reliably maintain the load-exerting action generated by the at least one bearing ring, it is proposed that the at least one bearing ring is held in the bearing bushing with an interference fit.
For a configuration that requires little maintenance, the bearing unit may be a plain bearing unit.
To implement the required sealing function, the at least one sealing element may be constructed with elastomer material.
The present disclosure furthermore relates to a method for producing a butterfly valve assembly constructed in accordance with the disclosure, including the measures:
The pressing-in of the at least one bearing ring causes such an axial load to be exerted on the at least one sealing element that the latter deflects radially inward, and a reliable sealing action is achieved as a result of the at least one sealing element abutting radially against the pivot shaft.
Here, the measures a) and b) may be carried out after the pivot shaft has been positioned so as to engage with one of its pivot shaft end portions into the bearing bushing of the at least one bearing region. In this approach, the at least one sealing element, and subsequently the at least one bearing ring, are positioned in the bearing bushing so as to encompass the pivot shaft end portion. Here, the at least one bearing ring is loaded in the direction of the sealing element that encompasses the pivot shaft end portion, in such a way that the at least one bearing ring subjects the at least one sealing element to axial load, and the sealing element is thus deformed, or deflects, radially inward in the direction of the pivot shaft that is already extending through the sealing element.
In an alternative approach, the measures a) and b) may be carried out before the pivot shaft is positioned so as to engage with one of its pivot shaft end portions into the bearing bushing of the at least one bearing region. For example, the at least one sealing element and the at least one bearing ring may be positioned in the bearing bushing before the bearing bushing is arranged on and fixed to the butterfly valve housing, which already contains the butterfly valve and thus also the pivot shaft.
The disclosure furthermore relates to a fuel cell system, in particular for a vehicle, including at least one butterfly valve assembly according to the disclosure, preferably produced by way of a method according to the disclosure.
The invention will now be described with reference to the drawings wherein:
Before the embodiment according to the disclosure of a butterfly valve assembly for a fuel cell system is described in detail below, in particular with regard to a structure thereof which is intended for providing a sealed closure, the basic construction of a fuel cell system which can be used to provide electrical energy in a vehicle will be described with reference to
The fuel cell system 100 illustrated in
The anode region 104 is assigned a feed line 108 and a discharge line 110 with respective valves 112, 114 in order to allow the hydrogen or the gas containing hydrogen to be introduced into the anode region 104 and/or to allow anode off-gas to be discharged therefrom, and if necessary to allow the anode region 104 to be closed off entirely.
The cathode region 106 is assigned a feed line 116 via which the gas containing oxygen, for example air, can be introduced into the cathode region, for example via a compressor 118 or the like. A butterfly valve assembly denoted generally by 10 is provided in the feed line 116, via which butterfly valve assembly the gas flow via the feed line 116 can be regulated, or the cathode region 106 can be substantially gas-tightly closed off in its inlet region.
For the discharge of cathode off-gas, the cathode region 106 is assigned a discharge line 120. This leads to a fuel cell off-gas system 122 in which, for example, water contained in the cathode off-gas can be separated off using a water separator. Also arranged in the discharge line 120 is a further butterfly valve assembly 10′ via which the discharge line 120 and thus outlet region of the cathode region 106 can be substantially gas-tightly closed off.
A bypass line 124 runs between the feed line 116 and the discharge line 120 of the cathode region 106. A butterfly valve assembly 10″ is also arranged in the bypass line 124, via which butterfly valve assembly the gas flow via the bypass line 124 can be regulated or the bypass line 124 can be substantially gas-tightly closed off.
The construction of the fuel cell system 100 as illustrated in
The butterfly valve assembly 10 illustrated in
The butterfly valve 16 includes a disk-shaped butterfly valve element 24 which is supported so as to be pivotable about a pivot shaft 18 axis A and which has two butterfly valve element parts 20, 22, which each provide one valve wing. A butterfly valve seat 26 is provided on the butterfly valve housing 14 so as to be assigned to the butterfly valve 16, against which butterfly valve seat the butterfly valve 16 lies, when in a closed position, by way of a closure region 40 which is situated radially at the outside in relation to a central region Z of the butterfly valve 16.
To move the butterfly valve 16 between the closed position and a fully opened position, in which the disk-shaped butterfly valve element 24 is oriented substantially orthogonally with respect to the plane of the drawing and
Each of the two bearing regions 28, 30 includes a bearing bushing 42, 44, which is supported on the butterfly valve housing 14 and which is for example fixed to an outer circumferential surface thereof by welding and in which a respective axial end portion of the pivot shaft 18 is received so as to be rotatable about the pivot shaft axis A.
Of the two bearing regions 28, 30, the bearing region 28 forms a first bearing region in which a first pivot shaft end portion 48 of the pivot shaft 18 is rotatably mounted. The first pivot shaft end portion 48 projects axially beyond the first bearing region 28 in order to be coupled via the coupling arrangement 32 to the drive shaft 34. The bearing region 30 forms a second bearing region in which a second pivot shaft end portion 50 of the pivot shaft 18 is mounted so as to be rotatable about the pivot shaft axis A.
A bearing unit denoted generally by 62 is received in the bearing bushing 42. In the embodiment illustrated, the bearing unit 62 includes a bearing ring 64 which receives and radially supports the first pivot shaft end portion 48, and is thus configured as a plain bearing unit. The bearing ring 64 is received in the bearing bushing 42 with an interference fit, and thus held in a defined axial position on the circumferential wall 56 of the bearing bushing 42. The pivot shaft 18 may be supported axially on the bearing ring 64 by way of a flange-like pivot shaft head 66 which is provided on the first pivot shaft end portion 48. A preload force that holds the pivot shaft head 66 of the pivot shaft 18 in contact with the bearing ring 64 may be provided by a preload spring 68 which acts between the pivot shaft 18 or the coupling part 36, on the one hand, and the drive shaft 34 or the coupling part 38, on the other hand, such that the defined position of the bearing ring 64 in the bearing bushing 42 also determines a defined position of the pivot shaft 18, and thus of the butterfly valve 16 as a whole, in the butterfly valve housing 14.
To provide a gas-tight closure in the first bearing region 28, an annular-disk-shaped sealing element constructed with elastomer material is furthermore provided, which is denoted generally by 70. The sealing element 70 is held or clamped with a holding portion 72 between the bearing ring 64 and the base 58 of the bearing bushing 42. By way of a sealing portion 74, the sealing element 70 lies, radially at the inside, against an outer circumferential surface of the pivot shaft 18 under radial preload. An opening 76 through which the pivot shaft 18 extends is formed in the sealing portion 74. In
As a result of the sealing element 70 being subjected to axial load via the bearing ring 64 and the holding portion 72 being clamped axially between the bearing ring 64 and the base 58, the sealing element 70, which is in principle deformable but which is substantially not compressible, is subjected to load in a radially inward direction, such that the holding portion 74 is pressed with greater intensity against an outer circumferential surface of the pivot shaft 18. To achieve areal abutting contact between the sealing element 70 and the base 58, the base 58 is substantially planar, and oriented orthogonally with respect to the pivot shaft axis A, in its region that axially supports the sealing element 70. Correspondingly, the bearing ring 64 is also substantially planar, and oriented orthogonally with respect to the pivot shaft axis A, at its end side which presses the sealing element 70 against the base 58.
Correspondingly to the substantially planar form of the base 58, the butterfly valve housing 14 may also, in its region that supports the bearing bushing 42, be substantially planar and oriented orthogonally with respect to the pivot shaft axis A. In particular, this also applies if the bearing bushing 42 has no base, and the sealing element 70 is thus pressed against the outer circumferential surface 54 of the butterfly valve housing 14 by the bearing ring 64.
In order to be able to reliably maintain the state in which the sealing element 70 is pressed radially against the pivot shaft 18 by axial exertion of load, the bearing ring 64 is received in the bearing bushing 42 with an interference fit, as already stated. This interference fit, or the friction force generated here between the bearing ring 64 and the circumferential wall 56 of the bearing bushing 42, is of such intensity that, when a force F that is applied in order to press the bearing ring 64 in is withdrawn after the bearing ring 64 has been pressed in, the bearing ring 64 reliably remains in its position in the bearing bushing 42 in which the bearing ring exerts axial load on, and thus radially inwardly deforms, the sealing element 70.
In the construction of the butterfly valve assembly 10 illustrated in
In principle, such a structure could also be provided in the second bearing region 30. Since it is however not intended for the pivot shaft 18 to be led out in the second bearing region 30, a gas-tight closure can for example also be achieved by virtue of the bearing bushing 44 of the second bearing region 30 completely encapsulating, that is, also axially encapsulating, the second pivot shaft end portion, for example by virtue of a cover which axially closes off the bearing bushing 44 being provided on a circumferential wall of the bearing bushing 44.
A butterfly valve assembly constructed in accordance with the disclosure may also be used in other applications, in particular also in the case of static fuel cell systems.
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
10 2022 120 289.5 | Aug 2022 | DE | national |
23 183 539.8 | Jul 2023 | EP | regional |