Valve assembly, in particular shut-off valve assembly for a fuel cell system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PUREM GMBH
- Filing Date
- 2025-12-01
- Publication Date
- 2026-07-30
Smart Images
Figure EP2025084857_30072026_PF_FP_ABST
Abstract
Description
[0001] Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0002] - 1 -
[0003] Valve assembly, in particular shut-off valve assembly for a fuel cell system
[0004] Description
[0005] The present invention relates to a valve assembly which can be used, for example, as a shut-off valve assembly, bypass valve assembly or control valve assembly to selectively release, interrupt or adjust the intensity of gas flows to or from one or more fuel cells in a fuel cell system, for example in a vehicle.
[0006] In the operation of a fuel cell supplied with hydrogen (H₂) or hydrogen-containing gas at the anode and with oxygen (O₂)-containing gas, such as air, at the cathode, water or water vapor is produced in the cathode. This water is released from the fuel cell with the cathode exhaust and, for example, expelled to the environment via an exhaust system. Water can also accumulate in the anode, having diffused through a membrane separating the cathode and anode. Such water or water vapor accumulated in the anode, along with other generally gaseous impurities that accumulate there, can be expelled from the anode during a purge process and released to the environment via an exhaust system.
[0007] To interrupt or release a flow of cathode exhaust gas from a cathode output, or to interrupt or release a flow of anode exhaust gas from an anode output, valve units designed, for example, like control flaps can be used. In these units, a flap, actuated by an electric motor with a drive torque or force, provides a valve element and is adjusted between a closed position (interrupting the flow of cathode or anode exhaust gas) and an open position (releasing the flow of cathode or anode exhaust gas). This also applies to shutting off and releasing a cathode input. (Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG)
[0008] - 2 -
[0009] Such a valve unit can be used to supply oxygen-containing air as cathode gas to a cathode inlet.
[0010] At very low ambient temperatures, water accumulating in the area of such a valve unit can freeze, thereby blocking the flap that acts as the valve element from moving. This condition can occur particularly when, for example, a fuel cell system integrated into a vehicle is not active while the vehicle is parked outdoors. Since, in such a condition, the various valve units of the fuel cell system are generally in a closed position, there is a risk that when the vehicle or the fuel cell system is started, such a frozen valve unit cannot be moved into a state that allows flow, and therefore the fuel cell system cannot be used to generate electrical energy.
[0011] To counteract this problem, it is possible to apply a relatively high voltage to an electric motor installed in such a valve unit when the valve element (i.e., the flap) is in the closed position. This is done to force the flap towards the open position, generating a sufficiently high torque to break free from the frozen flap. However, this approach can lead to the problem that, in order to generate a sufficiently high torque, the voltage applied to the electric motor must be so high that the windings of the motor, which is operating in a short circuit with the flap initially stationary, can be damaged. Furthermore, a sudden release of the flap by the electric motor can result in an undefined, jerky movement of the flap towards the open position.
[0012] The object of the present invention is to provide a valve assembly, in particular a shut-off valve assembly for a fuel cell system, in which a valve element blocked by icing can be released without the risk of damaging system areas of the valve assembly and without the occurrence of undefined states of the valve element. Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0013] - 3 -
[0014] According to the invention, this problem is solved by a valve assembly, in particular a shut-off valve assembly for a fuel cell system, comprising:
[0015] a valve unit with a valve element adjustable between a closed position that essentially interrupts the flow of the medium and an open position that releases the flow of the medium,
[0016] an electric motor to actuate the valve element to move it between the closed position and the open position,
[0017] a control unit that controls the electric motor to actuate the valve element.
[0018] The control unit is designed to actuate the electric motor to actuate the valve element in the direction of the closing position when the valve element is in the closed position, and / or to actuate the electric motor to actuate the valve element in the direction of the open position when the valve element is in the open position.
[0019] In the present invention, the electric motor, which is generally used to move a valve element, is operated in a state where the valve element is frozen and thus blocked from movement, by energizing its windings in a short circuit and thereby used as a heater. Since in this state no attempt is made to break the valve element free, but rather the valve element is subjected to the torque generated by the electric motor in a direction in which further movement is fundamentally impossible, the electrical voltage applied to the electric motor can be selected such that the short-circuit current flowing in this state is sufficiently high to heat the valve assembly, particularly in the area of the valve element, by heating the windings of the electric motor and thereby thawing the ice blocking the valve element from movement.A short-circuit current high enough to generate sufficient torque to break free of the valve element is not required. If the heat generated by the short-circuit current eliminates the icing condition, allowing the valve element to move again from its iced state, then the following applies: Forehands-Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG.
[0020] - 4 -
[0021] Since the valve is in a free position, there is no risk of it spontaneously and unpredictably moving out of that position. Rather, it is first necessary to terminate the current flowing to the electric motor, which is acting on the valve in a direction where further movement is fundamentally impossible, and then to control the motor in such a way that a defined movement of the valve subsequently occurs from its current position, or the position it occupies while frozen.
[0022] It should be noted that in the valve assembly constructed according to the invention, the measures for eliminating icing by heating the valve assembly using the energized electric motor can be implemented both when the valve element freezes in the closed position and is thus blocked against movement, and when the valve element freezes in the open position and is thus blocked against movement. Alternatively, the valve assembly according to the invention can also be constructed such that, for example, because such icing can or will only occur in the closed position or only in the open position, these measures are implemented only in connection with the position critical with regard to icing and thus blockage of the valve element, i.e., only in connection with the closed position or only in connection with the open position.
[0023] To specify a defined positioning of the valve element, a closing position stop can be provided, whereby when the valve element is positioned in the closed position, the valve element is blocked against further movement towards the closed position by the closing position stop, or / and an open position stop can be provided, whereby when the valve element is positioned in the open position, the valve element is blocked against further movement towards the open position by the open position stop.
[0024] The valve unit can comprise a valve housing with a housing body providing an electric motor intake volume and a valve element intake volume. Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0025] - 5 -
[0026] In order to achieve an efficient and as uniform a distribution as possible of the heat generated by the electric motor, it is particularly advantageous if the housing body is formed in one piece, at least in the area providing the electric motor intake volume and the valve element intake volume.
[0027] The design of the housing body with a material that conducts heat well, especially metal material such as steel or aluminum or aluminum-containing material, or plastic material, is also particularly advantageous.
[0028] In order to detect the potential danger of icing of the valve element using simple means, it is proposed that at least one temperature sensor be provided, and that the control unit be designed to actuate the electric motor to actuate the valve element towards the closing position when the valve element is in the closed position, and / or to actuate the electric motor to actuate the valve element towards the open position when the valve element is in the open position, if a temperature signal output by the at least one temperature sensor indicates a temperature below a first threshold temperature.
[0029] For the most precise determination possible of whether or not there is a potential risk of icing, it is advantageous if the temperature sensor for detecting a temperature is arranged in the area of the valve assembly, for example in the area of the housing body.
[0030] In an alternative design, which allows the movement or lack thereof of the valve element to be detected using simple means, a current sensing unit is provided to detect the motor current flowing through the electric motor. The control unit is designed to activate the electric motor to actuate the valve element towards the closed position when the motor current exceeds a threshold current, and / or when the valve element is in the closed position and actuated towards the open position. [posi-Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG]
[0031] - 6 -
[0032] to actuate the electric motor to actuate the valve element in the direction of the open position when, with the valve element positioned in the open position and actuated in the direction of the closing position, the motor current exceeds a threshold current.
[0033] In order to determine the position of the valve element and, in particular, to be able to take the correct control measure in the event of icing, in accordance with the respective position of the valve element, at least one position sensor can be provided to detect the position of the valve element.
[0034] In order to be able to deduce whether an icing condition exists, taking into account the output signal of the position sensor, the control unit can be designed to actuate the electric motor to actuate the valve element towards the closing position when the valve element is in the closed position, if the position sensor does not detect any movement of the valve element from the closed position when the valve element is in the closed position and actuated towards the open position, or / and to actuate the electric motor to actuate the valve element towards the open position when the valve element is in the open position and actuated towards the closing position when the position sensor does not detect any movement of the valve element from the open position.
[0035] The invention further relates to a fuel cell system comprising at least one fuel cell and at least one valve assembly constructed according to the invention for selectively shutting off and releasing a gas flow from the at least one fuel cell and / or for selectively shutting off and releasing a gas flow to the at least one fuel cell.
[0036] The invention further relates to a method for operating a valve assembly constructed according to the invention, preferably in a fuel cell system constructed according to the invention, comprising the following measures:
[0037] a) Determine whether the valve element is iced up, Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0038] - 7 -
[0039] (b) Activating the electric motor to actuate the valve element in the direction of the closing position when the valve element is positioned in the closed position, if in step (a) the presence of an icing condition of the valve element was determined,
[0040] or / and
[0041] b2) Controlling the electric motor to actuate the valve element in the direction of the open position when the valve element is positioned in the open position, if in step a) the presence of an icing condition of the valve element was determined.
[0042] In this context, it should also be noted that measures bi) and b2) can be provided in combination in the method according to the invention, so that, depending on whether a potentially critical icing condition is detected when the valve element is in the closed position or in the open position, the respective measure for heating the valve unit by the energized electric motor can be carried out. If, for example, it can be assumed that such an icing condition can or will only occur in one of the end positions of the valve element, then only the measure bi) or b2) associated with the potentially critical end position can be implemented in the method according to the invention.
[0043] To determine whether a potentially critical icing condition exists with regard to a blockage of the valve element, in measure a) a temperature, preferably in the area of the valve assembly, can be recorded, and the existence of an icing condition of the valve element can be determined if the temperature is below a first threshold temperature.
[0044] This shows that, in accordance with the present invention, even on the basis of information that suggests the possibility of an icing condition but does not prove it, the existence of an icing condition can be determined in order to take the measures according to the invention as soon as the potential danger of such a condition is recognized. Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0045] - 8 -
[0046] An alternative procedure for detecting whether or not an icing condition exists may involve the following: in measure a) with the valve element in the closed position, the electric motor is activated to actuate the valve element towards the open position, and the presence of an icing condition of the valve element is determined if, with the valve element in the closed position and actuated towards the open position, the valve element does not move towards the open position; or / and in measure a) with the valve element in the open position, the electric motor is activated to actuate the valve element towards the closed position, and the presence of an icing condition of the valve element is determined if, with the valve element in the open position and actuated towards the closed position, the valve element does not move towards the closed position.
[0047] With this approach, for example, when the fuel cell system is put into operation, the electric motor can initially be controlled in such a way as is necessary to move the valve into the position intended for the subsequent operation of the fuel cell system. In measure a), the electric current flowing through the electric motor can then be monitored, and the absence of movement of the valve, i.e., a blockage of the valve, particularly due to icing, can be detected if the electric current flowing through the electric motor exceeds a threshold current.An electric current exceeding a threshold current indicates that the expected response of the valve element when an electrical voltage is applied to the electric motor—namely, its movement from its current position—does not occur. This suggests that the valve element is most likely blocked from movement by icing. The operational reliability of the valve assembly can be increased by combining the two aforementioned measures: temperature detection and motor current monitoring. For example, if a comparatively low temperature is detected along with an excessively high motor current, it can be assumed with a high degree of certainty that the valve element is iced up. [The following appears to be unrelated and possibly a separate document fragment: Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG.]
[0048] - 9 -
[0049] If the temperature recorded simultaneously falls within a range where icing appears unlikely or impossible, a defect in the valve assembly can be inferred. This can then be used as a trigger for a corresponding warning.
[0050] In order to be able to take the correct control measure for de-icing the valve assembly in the event of icing, depending on the current position of the valve element, it is proposed that in measure a) it is determined, based on the output signal of the position sensor, whether the valve element is positioned in the closed position, or / and that in measure a) it is determined, based on the output signal of the position sensor, whether the valve element is positioned in the open position.
[0051] An alternative approach to determining whether the valve element moves when the electric motor is energized involves measure a) detecting the absence of valve movement if the position sensor's output signal indicates no change in the valve element's position. This measure can also be combined with temperature monitoring, so that if a comparatively high temperature is present, making icing unlikely, a fault condition can be inferred and appropriate safety measures can be taken.
[0052] To ensure that, after taking the defrosting measures according to the invention for the valve assembly, the valve element can be brought into the position intended for subsequent operation, the method can include a measure ci) for detecting a temperature, preferably in the area of the valve assembly, while in measure bi) the electric motor is actuated to actuate the valve element in the direction of the closing position, wherein, if the temperature detected in measure ci) is above a second threshold temperature, the actuation of the electric motor to actuate the valve element in the direction of the closing position is terminated when the valve element is positioned in the closed position, and / or the method can include a measure C2).
[0053] - 10-
[0054] sen to detect a temperature, preferably in the area of the valve assembly, while in measure b2) the electric motor is activated to actuate the valve element in the direction of the open position, and that when the temperature detected in measure C2) is above a second threshold temperature, the activation of the electric motor to actuate the valve element in the direction of the open position is terminated with the valve element positioned in the open position.
[0055] An alternative approach may involve that, in measure bi), the electric motor is activated for a predetermined period of time to actuate the valve element in the direction of the closed position, and / or that, in measure b2), the electric motor is activated for a predetermined period of time to actuate the valve element in the direction of the open position.
[0056] The present invention is described in detail below with reference to the accompanying figures. These show:
[0057] Fig. 1 shows a sectional view of a valve unit of a valve assembly designed as a control flap;
[0058] Fig. 2 shows a basic representation of a valve assembly used in conjunction with a fuel cell.
[0059] Fig. 1 shows a valve unit 10 designed in the manner of a control flap, which can be used in a valve assembly 12 described in detail below with reference to Fig. 2 to selectively open and close a flow path for a medium, in particular a gaseous medium.
[0060] The valve unit 10 comprises a valve housing 14, in which, for example, a channel-shaped valve element receiving volume 16 and, for example, a pot-shaped electric motor receiving volume 18 are formed. A valve element 20, designed as a disc-shaped flap, is supported on a pivot shaft 22 in the valve element receiving volume 16. The pivot shaft 22 is connected to the valve housing 14 on both sides of the valve element 20 by means of respective bearing arrangements 24, 26.
[0061] - 11 -
[0062] The valve element 20 is rotatably mounted so that by rotating the pivot shaft 22 about its longitudinal axis, it can be moved between a closed position shown in Fig. 1, in which a flow path through the housing 14 is essentially closed, and an open position, in which the flow path through the valve housing 14 is released.
[0063] To generate this movement of the valve element 20 or the pivot shaft 22 supporting it, an electric motor 28 is positioned in the electric motor housing 18. A rotor 30 of the electric motor 28, only indicated in principle in Fig. 1, is coupled to the pivot shaft 22 by means of a gear arrangement 32, not shown in detail in Fig. 1, so that by energizing the electric motor 28 and thereby causing rotation of the rotor 30, the pivot shaft 28 is driven to rotate and the valve element 20 is moved between its closed position and its open position.
[0064] The gear arrangement 32 can, for example, include a stepped gear 34 which has a gear section with a larger diameter which meshes with a drive gear 36 provided on the rotor 30 of the electric motor 28, and a gear section with a smaller diameter which meshes with a segment gear 38 which is rotationally fixed to the pivot shaft 22.
[0065] The valve element 20 is associated with a closing position stop 40 on the valve housing 14, for example, provided by a valve seat. The valve element 20 rests on the valve seat with its outer circumference in the closed position, thus achieving a substantially gas-tight seal of the flow path passing through the valve housing 14. For this purpose, a sealing element made of elastic material can be provided, for example, on the outer circumference of the valve element 20 and / or on the closing position stop 40. To avoid excessive compression of such a sealing element, the closing position stop 40 can alternatively be provided at a different location, for example, in the area of the pivot shaft 22 or the gear assembly 32, so that movement of the valve element 20 towards the closed position is prevented by the closing position stop.
[0066] - 12 -
[0067] The lung stop 40 is terminated or blocked when the sealing element is already effective in creating a tight seal, but before it is excessively compressed.
[0068] It should be noted that the valve unit 10 shown in Fig. 1 is representative of a multitude of different possible configurations of such a valve unit designed in the manner of a control flap. These possible configurations relate, for example, to the torque transmission between the electric motor 28 and the pivot shaft 22, i.e., the design of the gear unit 32, or to the bearing arrangement of the pivot shaft 22 on the valve housing 14. The positioning of the valve element receiving volume 16 relative to the electric motor receiving volume 18 can also be chosen differently, whereby, for the reasons explained below, positioning these two volumes relatively close to each other and, in particular, within a housing body 42 of the valve housing 14 formed in one piece, preferably with metal material, for example steel or aluminum, or with a good thermal conductivity in plastic, is particularly advantageous.Although a one-piece construction of the housing body 42 is particularly advantageous in its area providing the valve element receiving volume 16 and the electric motor receiving volume 18 due to the good thermal conductivity, a multi-piece construction of the housing body 42 is also possible in principle in this area.
[0069] Figure 2 shows a fuel cell system 44, for example, that can be used in a vehicle to generate electrical energy. The fuel cell system 44 comprises a fuel cell 46, for example, configured as a fuel cell stack, with an anode section 48 and a cathode section 50. During fuel cell operation, hydrogen (H2) or hydrogen-containing anode gas is supplied to the anode section 48 at an anode inlet 54 from a storage tank 52, which can be shut off by a hydrogen shut-off valve 51. During fuel cell operation, air, i.e., a cathode gas containing oxygen (O2), is supplied to the cathode section 50 at a cathode inlet 56, for example, by means of a blower, compressor, or the like. Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0070] - 13-
[0071] During fuel cell operation, cathode exhaust gas containing water or water vapor is produced in the cathode region 50. This gas can be discharged from the fuel cell 46 via a cathode outlet 58 towards an exhaust system 60 and from there to the environment. For purge operations, anode exhaust gas accumulating in the anode region 48 can be directed towards the exhaust system 60 via an anode outlet 62, for example, either together with the cathode exhaust gas stream or in phases instead of the cathode exhaust gas stream.
[0072] The valve assembly 12, described in detail below with regard to its structure and function, is assigned to the cathode outlet 58 in the illustrated embodiment of a fuel cell system, so that the cathode exhaust gas leaving the cathode outlet 58 can be directed to the exhaust system 60 via the valve unit 10 when the valve element 20 is in the open position. When the valve element 20 is in the closed position, the cathode outlet 58 is sealed off against the escape of cathode exhaust gas.
[0073] Figure 2 shows that a cathode inlet valve 62 is associated with the cathode inlet 56 to selectively allow or interrupt the flow of oxygen-containing cathode gas, i.e., the flow of air, into the cathode region 50. An anode outlet valve 66 is associated with the anode outlet 62, through which the anode outlet 62 can be opened, for example, to perform purge operations, and thus anode exhaust gas can be discharged from the anode region 48.
[0074] It should be noted that the valve assembly 12 shown in the fuel cell system 44 of Fig. 2 in connection with the cathode outlet 58, i.e., as a cathode outlet valve, could also be used in the same way as a cathode inlet valve 64 or as an anode outlet valve 66. In particular, such a valve assembly 12 can be used in the context of a fuel cell system 44 in connection with such flow paths in which a gaseous medium containing water (H2O) flows and there is therefore a potential risk of condensation and, at low ambient temperatures,
[0075] - 14-
[0076] If water freezes, icing occurs and the valve element 20 is blocked against movement. Since this risk is potentially greatest in the context of a fuel cell system in connection with the cathode outlet 58, the valve assembly 12 is shown in connection with the cathode outlet 58, without being limited to this application.
[0077] Water generated in the cathode region 50 during fuel cell operation, or transported in the cathode exhaust gas, can condense in the area of the valve unit 10. This condensation can occur, particularly when the fuel cell system 44 is deactivated at relatively low ambient temperatures, in the area of the valve element 20, which is generally in its closed position when the fuel cell system is deactivated. Such icing can block the valve element 20 from moving out of the closed position, preventing the flow path through the cathode region 50 from being opened during a subsequent attempt to start the fuel cell system 44.
[0078] To counteract this problem, the fuel cell system 44 and the valve assembly 12 are designed so that, when such an icing condition exists or there is a potential risk of such an icing condition, the electric motor 28, controlled by a control unit 68, is initially controlled in such a way that it generates a torque acting on the valve assembly 20 in the direction of its closed position when the valve element 20 needs to be moved from its closed position to the open position for the commissioning of the fuel cell system 44. The existence of the closed position of the valve element 20 can be detected or verified in the valve assembly 12 by, for example, a position sensor 74 that detects the rotational position of the pivot shaft 22, and whose output signal, representing the rotational position of the pivot shaft 22, is supplied to the control unit 28.Since, when the valve element 20 is in the closed position, it is already in contact with the closed-position stop 40, further movement of the valve element 20 in this direction is essentially impossible. The valve element 20 thus also blocks the movement of the electric motor 28 or its rotor, which leads to the following: Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG.
[0079] - 15-
[0080] This is because, due to the electrical voltage applied to the electric motor 20 by means of the control unit 68, generally to the stator windings of the DC electric motor 28, a short-circuit current flows through the electric motor 28 or its windings. This short-circuit current leads to heating of the electric motor 28, which in turn heats the surrounding area of the valve housing 14 or the housing body 42. Since, as shown in Fig. 1, the electric motor 28 is positioned relatively close to the valve element 20, the area of the housing body 42 surrounding the valve element 20 or the valve element receiving volume 16 is also heated, with the result that the valve element 20 thaws any blocking ice and, at the end of this de-icing process, the valve element 20 is free to move from its closed position.
[0081] To ensure that such a measure, which would generally delay the commissioning of the fuel cell system 44, is only necessary when actually required, a temperature sensor 70, advantageously positioned close to the valve element 20, can be provided, for example, in conjunction with the valve housing 14. Its output signal indicates the temperature in the area of the valve housing 14 or the valve element 20 and can thus be used as an indicator of whether there is a potential risk of icing. For this purpose, a first threshold temperature can be specified, which, for example, could be in a range between 0°C and -10°C.If it is detected that the temperature detected by the temperature sensor 70 in the area of the valve unit 10 is below this first threshold temperature, the preceding procedure for energizing the electric motor 28 in such a way that it generates a torque that further acts on the valve element 20, which is already positioned in its closed position, can be initiated.
[0082] For an alternative approach to deciding whether a de-icing process is necessary or not, a current sensing unit 72 can be assigned to the electric motor 28. This unit detects the electric current flowing through the electric motor 28 and generates a signal indicating this current, which is then evaluated in the control unit 68. Upon commissioning of the fuel cell system 44, the electric motor 28 can then initially be controlled, as would generally be required, such that it opens the valve element 20 from its closed position.
[0083] - 16-
[0084] The electric motor 28 generates a torque moving the valve towards its open position and applies this torque to the valve element 20. If the valve element is blocked from moving from its closed position due to icing, a short-circuit current will flow in the electric motor 28, which is significantly higher than the current that would flow during normal operation and the onset of movement of the valve element 20. If it is detected that the electric current flowing through the electric motor 28 is greater than a threshold current, this can be interpreted as an indicator that, despite the electrical voltage applied to the electric motor 28 and the electric current flowing through it, no movement of the valve element 20 has occurred.This in turn can be interpreted as an indicator that the valve element 20 is blocked against movement by icing, so that the measure described above is subsequently taken and the electric motor 28 is controlled in such a way that it generates a torque that initially acts on the valve element 20 in its closed position in order to carry out a de-icing process with the heat then generated in the electric motor 28 in this state.
[0085] In another alternative approach to detecting whether the valve element 20 is blocked against movement from its closed position, the output signal of the position sensor 74 can be used to determine whether, with the valve element 20 being actuated towards the open position or with the electric motor 28 being energized accordingly, the pivot shaft 22 and with it the valve element 20 begin to move. If this is not the case, it can be concluded that a condition exists in which the valve element 20 is blocked against movement from the closed position detected by the output signal of the position sensor 74, which generally indicates that an icing condition is present.
[0086] The measures described above for detecting or recognizing whether an icing condition exists can be combined with each other, so that if, on the one hand, an excessively high current through the electric motor 28 and / or the output signal of the position sensor 74 indicates that the valve element 20 is not moving from the closed position, and on the other hand, the temperature sensor Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0087] - 17-
[0088] If the temperature measured by sensor 70 indicates a potential risk of icing, it can be determined with greater certainty that icing is actually present. If the temperature measured by sensor 70 is in a range where icing is generally not expected, an excessively high current flowing through the electric motor 28 can be interpreted as an indicator of a malfunction in the valve unit 10, and a corresponding warning can then be generated. Since, with such a combination of information, the temperature does not necessarily have to be measured in the area of the valve assembly 12, a temperature signal present in a vehicle, representing, for example, the ambient temperature, can be used.
[0089] In order to avoid damage to the electric motor 28, particularly in its windings, during the de-icing function to be carried out according to the invention, the output signal of the current sensing unit 72 can be used to adjust the electric current flowing through the electric motor 28 in this state or to apply a corresponding voltage to the electric motor 28 so that damage to the electric motor 28 cannot occur in principle.Such a voltage, which leads to a short-circuit current through the electric motor 28 suitable for heating the valve unit 10 in a sufficiently short time, is generally lower than a voltage applied to the electric motor 28 in normal operation, with which a movement of the valve element 20 between its open position and its closed position is actually effected, or is selected in such a way that a threshold current that excludes damage to the electric motor 28 is not exceeded.
[0090] To end the defrosting function, a predetermined time period can be set, for example, which ensures that the electric motor 28 can provide sufficient heat to remove the blockage of the valve element 20 caused by icing, even at very low ambient temperatures down to -40°C. Alternatively, it is possible to infer from the temperature detected by the temperature sensor 70 in the area of the valve unit 10 that it has warmed up sufficiently, particularly in the area of the valve element 20, and that the icing has therefore been eliminated. This also depends on Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG
[0091] - 18-
[0092] Depending on the positioning of the temperature sensor 70, a second threshold temperature can be specified. If the temperature detected by the temperature sensor 70 is above the second threshold temperature, which is above the first threshold temperature, the defrosting operation can be terminated and the electric motor 28 can then be excited by applying a corresponding voltage to generate a torque that acts on the valve element 20 in the direction of its open position.
[0093] Finally, it should be noted that the de-icing functionality described above can also be provided if there is a potential risk that the valve element 20, when positioned in its open position, is blocked from moving towards the closed position due to icing. This could be the case, for example, if, in a deactivated system, such as the fuel cell system 44, the valve unit 10 remains in a state with the valve element 20 in the open position.In this case too, if the position of the valve element 20 in its open position is detected by the position sensor 74 and an icing condition is found, the electric motor 28 can first be controlled in such a way that it generates a torque acting on the valve element 20 in its open position in order to remove any previously existing icing by the heating that occurs in the area of the valve element 20.
Claims
Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG - 19- Claims 1. Valve assembly, in particular a shut-off valve assembly for a fuel cell system, comprising: a valve unit (10) with a valve element (20) adjustable between a closed position which substantially interrupts the flow of the medium and an open position which releases the flow of the medium, an electric motor (28) for actuating the valve element (20) to move it between the closed position and the open position, a control unit (68) for actuating the electric motor (28) to actuate the valve element (20), wherein the control unit (68) is designed to actuate the electric motor (28) to actuate the valve element (20) in the direction of the closing position when the valve element (20) is in the closed position and / or to actuate the electric motor (28) to actuate the valve element (20) in the direction of the open position when the valve element (20) is in the open position.
2. Valve assembly according to claim 1 , characterized in that a closing position stop (40) is provided, wherein, when the valve element (20) is positioned in the closed position, the valve element (26) is blocked against further movement towards the closed position by the closing position stop (40), or / and that an open position stop is provided, wherein, when the valve element is positioned in the open position, the valve element (20) is blocked against further movement towards the open position by the open position stop.
3. Valve assembly according to claim 1 or 2, characterized in that the valve unit (10) comprises a valve housing (14) with a housing body (42) providing an electric motor intake volume (18) and a valve element intake volume (16).
4. Valve assembly according to claim 3, Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG - 20 - characterized in that the housing body (42) is formed in one piece at least in its area providing the electric motor receiving volume (18) and the valve element receiving volume (16).
5. Valve assembly according to claim 3 or 4, characterized in that the housing body (42) is constructed with metal material, preferably steel or aluminium or aluminium-containing material, or with plastic material.
6. Valve assembly according to one of claims 1-5, characterized in that at least one temperature sensor (70) is provided, and that the control unit (68) is configured to actuate the electric motor (28) to actuate the valve element (20) in the direction of the closing position when the valve element (20) is in the closed position, and / or to actuate the electric motor (28) to actuate the valve element (20) in the direction of the open position when the valve element (20) is in the open position, if a temperature signal output by the at least one temperature sensor (70) indicates a temperature below a first threshold temperature.
7. Valve assembly according to claim 6, characterized in that the temperature sensor (70) is arranged in the area of the valve assembly (12) for detecting a temperature.
8. Valve assembly according to one of claims 1-7, characterized in that a current sensing unit (72) is provided for sensing a motor current flowing through the electric motor (28), and that the control unit (68) is configured to actuate the electric motor (28) to actuate the valve element (20) in the direction of the closing position when the valve element (20) is positioned in the closed position and actuated in the direction of the open position, if the motor current exceeds a threshold current, or / and when the valve element (20) is positioned in the open position. Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG - 21 - The electric motor (28) is to be driven to actuate the valve element (20) in the direction of the open position when, with the valve element (20) positioned in the open position and actuated in the direction of the closing position, the motor current exceeds a threshold current.
9. Valve assembly according to one of claims 1-8, characterized in that at least one position sensor (74) is provided for detecting a position of the valve element (20).
10. Valve assembly according to claim 9, characterized in that the control unit (68) is designed to actuate the electric motor (28) to actuate the valve element (20) in the direction of the closing position when the valve element (20) is positioned in the closed position, if the position sensor (74) does not detect any movement of the valve element (20) from the closed position, or / and if the valve element (20) is positioned in the open position, to actuate the electric motor (28) to actuate the valve element (20) in the direction of the open position, if the position sensor (74) does not detect any movement of the valve element (20) from the open position.
11. Fuel cell system comprising at least one fuel cell (46) and at least one valve assembly (12) according to one of claims 1-10 for selectively shutting off and releasing a gas flow from the at least one fuel cell (46) and / or for selectively shutting off and releasing a gas flow to the at least one fuel cell (46).
12. Method for operating a valve assembly (12) according to one of claims 1-10, preferably in a fuel cell system (44) according to claim 11, comprising the measures: a) Determine whether the valve element (20) is iced up, Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG - 22 - bi) Controlling the electric motor (28) to actuate the valve element (20) in the direction of the closing position when the valve element (20) is positioned in the closed position, if in step a) the presence of an icing condition of the valve element (20) was determined, or / and b2) Controlling the electric motor (28) to actuate the valve element (26) in the direction of the open position when the valve element (20) is positioned in the open position, if in step a) the presence of an icing condition of the valve element (20) was determined.
13. Method according to claim 12, characterized in that in measure a) a temperature, preferably in the area of the valve assembly (12), is detected, and that the presence of an icing state of the valve element (20) is determined when the temperature is below a first threshold temperature.
14. Method according to claim 12 or 13, characterized in that, in measure a), with the valve element (20) positioned in the closed position, the electric motor (28) is actuated to actuate the valve element (20) in the direction of the open position, and that the presence of an icing condition of the valve element (20) is detected if, with the valve element (20) positioned in the closed position and actuated in the direction of the open position, the valve element (20) does not move in the direction of the open position, or / and that, in measure a), with the valve element (20) positioned in the open position, the electric motor (28) is actuated to actuate the valve element (20) in the direction of the closed position, and that the presence of an icing condition of the valve element (20) is detected if, with the valve element (20) positioned in the open position and actuated in the direction of the closed position, the valve element (20) does not move in the direction of the closed position.
15. Method according to claim 14, Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG - 23 - characterized in that in measure a) the electric current flowing through the electric motor (28) is monitored, and that the absence of movement of the valve element (20) is detected when the electric current flowing through the electric motor (28) is above a threshold current.
16. Method according to one of claims 12-15 in conjunction with claim 9, characterized in that in measure a) based on the output signal of the position sensor (74) it is determined whether the valve element (20) is positioned in the closed position, or / and that in measure a) based on the output signal of the position sensor (74) it is determined whether the valve element (20) is positioned in the open position.
17. Method according to claim 16, insofar as it refers back to claim 14, characterized in that in measure a) the absence of movement of the valve element (20) is detected when an output signal of the position sensor (74) does not indicate a change in the position of the valve element (20).
18. Method according to one of claims 12-17, characterized in that the method comprises a measure ci) for detecting a temperature, preferably in the area of the valve assembly (12), while in measure bi) the electric motor (28) is actuated to actuate the valve element (20) in the direction of the closing position, wherein, if the temperature detected in measure ci) is above a second threshold temperature, the actuation of the electric motor (28) to actuate the valve element (20) in the direction of the closing position is terminated when the valve element (20) is positioned in the closed position, and / or that the method comprises a measure C2) for detecting a temperature, preferably in the area of the valve assembly (12), while in measure b2) the electric motor (28) is actuated to actuate the valve element (20) in the direction of the open position, and that then,if the temperature recorded during measure C2) exceeds a second threshold temperature Purem GmbH 68964P DE-1 / 3323 DE / 1 SBS Feintechnik GmbH & Co. KG, - 24 - The actuation of the electric motor (20) to actuate the valve element (20) in the direction of the open position is terminated when the valve element (20) is positioned in the open position.
19. Method according to one of claims 12-18, characterized in that, in measure bi), the electric motor (28) is actuated for a predetermined period of time to actuate the valve element (20) in the direction of the closed position, or / and in measure b2), the electric motor (28) is actuated for a predetermined period of time to actuate the valve element (20) in the direction of the open position.