Butterfly valve assembly, in particular for a gas flow in a fuel cell system

A butterfly valve assembly includes a butterfly valve housing defining a channel for accommodating a flow of gas therethrough. The assembly includes a butterfly valve adjustable in the housing between a closed position preventing the flow of gas through the channel and an open position opening up the channel for allowing passage of the flow of gas. A pivot shaft is rotatable about a pivot shaft axis and has first and second pivot shaft end portions corresponding to first and second bearing regions. A disk-shaped butterfly valve element is supported on the pivot shaft. At least one of the first and second bearing regions includes a bearing unit rotatably supporting the pivot shaft. The pivot shaft has an outer peripheral surface. At least one seal is subject to an axial load by the bearing unit and lies against the outer peripheral surface of the pivot shaft.

CROSS-REFERENCE TO RELATED APPLICATIONS

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.

TECHNICAL FIELD

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.

BACKGROUND

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.

SUMMARY

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:a) arranging the at least one sealing element in a bearing bushing of the at least one bearing region,b) pressing at least one bearing ring of the bearing unit into the bearing bushing such that the at least one bearing ring subjects the at least one sealing element to axial load and the at least one sealing element is deformed radially inward by the axial load.

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.

DETAILED DESCRIPTION

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 toFIG.1, and the basic construction of a butterfly valve assembly which, in particular when assigned to the cathode region of such a fuel cell system, can be used to regulate the gas flow or shut off a flow through the cathode region, will be discussed with reference toFIG.2.

The fuel cell system100illustrated inFIG.1includes, as a main system region, a fuel cell denoted generally by 102, having an anode region104, which is to be fed with hydrogen or with a gas containing hydrogen, and having a cathode region106, which is to be fed with oxygen or with a gas containing oxygen, for example air.

The anode region104is assigned a feed line108and a discharge line110with respective valves112,114in order to allow the hydrogen or the gas containing hydrogen to be introduced into the anode region104and/or to allow anode off-gas to be discharged therefrom, and if necessary to allow the anode region104to be closed off entirely.

The cathode region106is assigned a feed line116via which the gas containing oxygen, for example air, can be introduced into the cathode region, for example via a compressor118or the like. A butterfly valve assembly denoted generally by 10 is provided in the feed line116, via which butterfly valve assembly the gas flow via the feed line116can be regulated, or the cathode region106can be substantially gas-tightly closed off in its inlet region.

For the discharge of cathode off-gas, the cathode region106is assigned a discharge line120. This leads to a fuel cell off-gas system122in which, for example, water contained in the cathode off-gas can be separated off using a water separator. Also arranged in the discharge line120is a further butterfly valve assembly10′ via which the discharge line120and thus outlet region of the cathode region106can be substantially gas-tightly closed off.

A bypass line124runs between the feed line116and the discharge line120of the cathode region106. A butterfly valve assembly10″ is also arranged in the bypass line124, via which butterfly valve assembly the gas flow via the bypass line124can be regulated or the bypass line124can be substantially gas-tightly closed off.

The construction of the fuel cell system100as illustrated inFIG.1and described above represents one example out of numerous different possibilities for the feed and discharge of gas, in particular at the cathode region106. It is essential that at least one and optionally several butterfly valve assemblies10,10′,10″ are provided so as to be assigned to the cathode region106, wherein, if several such butterfly valve assemblies10,10′,10″ are provided, these may in principle be structurally identical to one another, or may also be of different configuration depending on the region in which they are positioned and what degree of gas-tightness they are intended to provide.

The butterfly valve assembly10illustrated inFIG.2and used for example in the fuel cell system100ofFIG.1includes a butterfly valve drive12based for example on an electric motor and includes, in a butterfly valve housing14which is tubular and bounds a gas flow channel46, a butterfly valve denoted generally by 16.

The butterfly valve16includes a disk-shaped butterfly valve element24which is supported so as to be pivotable about a pivot shaft18axis A and which has two butterfly valve element parts20,22, which each provide one valve wing. A butterfly valve seat26is provided on the butterfly valve housing14so as to be assigned to the butterfly valve16, against which butterfly valve seat the butterfly valve16lies, when in a closed position, by way of a closure region40which is situated radially at the outside in relation to a central region Z of the butterfly valve16.

To move the butterfly valve16between the closed position and a fully opened position, in which the disk-shaped butterfly valve element24is oriented substantially orthogonally with respect to the plane of the drawing andFIG.1and thus substantially completely opens up the gas flow channel46in the butterfly valve housing14for a passage of flow, a drive shaft34of the butterfly valve drive12is coupled rotationally conjointly to the pivot shaft18, which is supported in bearing regions28,30on the butterfly valve housing14so as to be pivotable about the pivot shaft axis A, via a coupling arrangement32. Here, the coupling arrangement32includes, for example, a coupling part38, which is connected rotationally conjointly to the drive shaft34, and a coupling part36, which is connected rotationally conjointly to the pivot shaft18and which engages with the coupling part38with rotational coupling action.

Each of the two bearing regions28,30includes a bearing bushing42,44, which is supported on the butterfly valve housing14and which is for example fixed to an outer circumferential surface thereof by welding and in which a respective axial end portion of the pivot shaft18is received so as to be rotatable about the pivot shaft axis A.

Of the two bearing regions28,30, the bearing region28forms a first bearing region in which a first pivot shaft end portion48of the pivot shaft18is rotatably mounted. The first pivot shaft end portion48projects axially beyond the first bearing region28in order to be coupled via the coupling arrangement32to the drive shaft34. The bearing region30forms a second bearing region in which a second pivot shaft end portion50of the pivot shaft18is mounted so as to be rotatable about the pivot shaft axis A.

FIG.3illustrates the first bearing region28in detail. The first bearing region28includes the bearing bushing42, which is, for example, fixed gas-tightly to the outer circumferential surface54of the butterfly valve housing14by a fully encircling weld seam52. The bearing bushing42includes a circumferential wall56and a base58which adjoins the circumferential wall and which has an opening60through which the pivot shaft18extends. The bearing bushing42may also have only the circumferential wall56and no base wall, which, in particular in the case of the domed contour of the outer circumferential surface54of the butterfly valve housing14, allows the bearing bushing42to be more easily fixed to the butterfly valve housing14, also allows a configuration of the bearing bushing42which is easier to produce.

A bearing unit denoted generally by 62 is received in the bearing bushing42. In the embodiment illustrated, the bearing unit62includes a bearing ring64which receives and radially supports the first pivot shaft end portion48, and is thus configured as a plain bearing unit. The bearing ring64is received in the bearing bushing42with an interference fit, and thus held in a defined axial position on the circumferential wall56of the bearing bushing42. The pivot shaft18may be supported axially on the bearing ring64by way of a flange-like pivot shaft head66which is provided on the first pivot shaft end portion48. A preload force that holds the pivot shaft head66of the pivot shaft18in contact with the bearing ring64may be provided by a preload spring68which acts between the pivot shaft18or the coupling part36, on the one hand, and the drive shaft34or the coupling part38, on the other hand, such that the defined position of the bearing ring64in the bearing bushing42also determines a defined position of the pivot shaft18, and thus of the butterfly valve16as a whole, in the butterfly valve housing14.

To provide a gas-tight closure in the first bearing region28, an annular-disk-shaped sealing element constructed with elastomer material is furthermore provided, which is denoted generally by 70. The sealing element70is held or clamped with a holding portion72between the bearing ring64and the base58of the bearing bushing42. By way of a sealing portion74, the sealing element70lies, radially at the inside, against an outer circumferential surface of the pivot shaft18under radial preload. An opening76through which the pivot shaft18extends is formed in the sealing portion74. InFIG.3, a bearing play formed between the bearing ring64and the pivot shaft18is illustrated on an exaggerated scale in order to better illustrate the construction of the sealing element70.

As a result of the sealing element70being subjected to axial load via the bearing ring64and the holding portion72being clamped axially between the bearing ring64and the base58, the sealing element70, which is in principle deformable but which is substantially not compressible, is subjected to load in a radially inward direction, such that the holding portion74is pressed with greater intensity against an outer circumferential surface of the pivot shaft18. To achieve areal abutting contact between the sealing element70and the base58, the base58is substantially planar, and oriented orthogonally with respect to the pivot shaft axis A, in its region that axially supports the sealing element70. Correspondingly, the bearing ring64is also substantially planar, and oriented orthogonally with respect to the pivot shaft axis A, at its end side which presses the sealing element70against the base58.

Correspondingly to the substantially planar form of the base58, the butterfly valve housing14may also, in its region that supports the bearing bushing42, be substantially planar and oriented orthogonally with respect to the pivot shaft axis A. In particular, this also applies if the bearing bushing42has no base, and the sealing element70is thus pressed against the outer circumferential surface54of the butterfly valve housing14by the bearing ring64.

In order to be able to reliably maintain the state in which the sealing element70is pressed radially against the pivot shaft18by axial exertion of load, the bearing ring64is received in the bearing bushing42with an interference fit, as already stated. This interference fit, or the friction force generated here between the bearing ring64and the circumferential wall56of the bearing bushing42, is of such intensity that, when a force F that is applied in order to press the bearing ring64in is withdrawn after the bearing ring64has been pressed in, the bearing ring64reliably remains in its position in the bearing bushing42in which the bearing ring exerts axial load on, and thus radially inwardly deforms, the sealing element70.

In the construction of the butterfly valve assembly10illustrated inFIGS.2and3, the bearing ring64, and with it the sealing element70, can be positioned in the bearing bushing42before the pivot shaft is arranged on the butterfly valve housing14. Alternatively, if the bearing bushing42has already been attached to the butterfly valve housing14, it is possible for the pivot shaft18to firstly be positioned in the butterfly valve housing14, and thus with the pivot shaft end portion48in the bearing bushing42, before the bearing ring64and the sealing element70are positioned in the bearing bushing42. In order that the pivot shaft head66does not pose an obstruction during the assembly process, it is possible for the pivot shaft head to be arranged on the pivot shaft18, and fixed thereto for example by welding, only after the pivot shaft18has been positioned in the two bearing regions28,30.

In principle, such a structure could also be provided in the second bearing region30. Since it is however not intended for the pivot shaft18to be led out in the second bearing region30, a gas-tight closure can for example also be achieved by virtue of the bearing bushing44of the second bearing region30completely 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 bushing44being provided on a circumferential wall of the bearing bushing44.

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.