DE102016214773A1 - Method for checking the tightness of a hydrogen-carrying motor vehicle - Google Patents

Abstract

The technology disclosed herein relates to a method for checking the tightness of a motor vehicle with hydrogen-carrying components. The method may include the step of generating a gas flow around the motor vehicle and / or flowing through the motor vehicle within a hydrogen-tight enclosure. The method disclosed herein further includes the step of detecting hydrogen within the enclosure.

Description

The technology disclosed herein relates to a method for checking the tightness of a hydrogen-carrying motor vehicle. Further, the technology disclosed herein relates to a method of manufacturing a motor vehicle.

In the assembly of hydrogen-carrying parts (hydrogen fuel system, fuel cell system, hydrogen combustion engine, etc.) in a motor vehicle, the tightness of the systems must be very carefully checked. This is also necessary later in service in the workshop or as part of the main inspection ("TÜV"). This may be because the service and safety concept requires regular leak proofing or because hydrogen-carrying parts had to be replaced so that the tightness of the entire system can be proven again. The verification and the proof of the tightness with respect to hydrogen is very important, since escaping hydrogen with the oxygen of the air can form a combustible mixture and thus represents a security risk. For the proof of density different methods are considered. As a rule, proof of tightness is provided by the absence of escaping hydrogen.

Local processes and global processes can be imagined (the latter are also called "integral"): local processes seek local hydrogen leakage. This is for example possible by "sniffing" with a hydrogen probe. Also, localized spraying with leak detection spray, which responds to leaks due to blistering (similar to soap bubbles), belongs to this category.

In integral processes, the entire system of hydrogen-carrying components is examined for leakage. For the proof of tightness in production, assembly, service and in particular the integral methods make sense, since the local search is too time-consuming, because with the local search all potential leakage points would have to be examined, in order to lead the tightness proof. Immersion of the entire motor vehicle in a bubble-forming liquid is also not a viable solution, especially for a workshop.

Local hydrogen accumulations ("hydrogen bubbles"), especially unnoticed hydrogen accumulations, should be avoided for safety reasons.

It is a preferred object of the technology disclosed herein to reduce or eliminate at least one disadvantage of the previously known solutions. It is a preferred object to use mass production test methods that can be used without great delays, uncomplicated, reliable, in a small space and / or cost preferred for various motor vehicle series. Other preferred objects may result from the beneficial effects of the technology disclosed herein. The object (s) is / are solved by the subject matter of claim 1. The dependent claims are preferred embodiments.

The technology disclosed here relates in particular to integral methods for checking the tightness of a motor vehicle with hydrogen-carrying components. The processes collect the hydrogen leaks and thus ideally consider the sum of all leaks. For this, the ascending leaks can be caught in a kind of inverted funnel over the test object. It then collects the hydrogen at the highest point and can be detected there completely. Hydrogen is the lightest gas, which is the least dense, and thus always rises at ambient temperatures. (Alternatively, by immersing test objects in liquids (in the simplest case, water), hydrogen leaks may bubble up and collect above the liquid level, and by observing the beginning of the bubble traces, the leak points can be determined.

This solution is in the 1 shown. A disadvantage of this solution is that hydrogen trapped in cavities can not be detected. The hydrogen tanks and the other hydrogen-carrying components can be installed in the motor vehicle so that hydrogen leaks can not rise freely upwards. There is therefore the danger that the hydrogen which has flowed out instead gets trapped in "hydrogen bubbles" within the cavities of the body. Only when these cavities are completely filled with hydrogen, the hydrogen will be effectively "overrun" and detectable above the motor vehicle. The fact that the hydrogen gas rises, the vertical directions are reversed to the behavior of liquids. Thus, the "overflow" takes place at the bottom of the cavity.

The further idea of the technology disclosed here is to free the fuel trapped in cavities and to detect it via suitable detection means. For this purpose, various methods are disclosed below, which can also be combined with each other. In these methods, it is provided to pre-pressurize the hydrogen-containing components with hydrogen. For this purpose, the hydrogen introduced into the hydrogen-carrying components may for example have a differential pressure to Have environment of about 0.5 bar or 1 bar or more.

• – Überführen des Kraftfahrzeugs aus einer Gebrauchsposition des Kraftfahrzeugs in eine Überkopf-Position des Kraftfahrzeugs, wobei das Kraftfahrzeug zumindest während des Überführens von einer wasserstoffdichten Einhausung umgeben sein kann; und
• – Detektieren von aus dem Kraftfahrzeug ausströmenden bzw. ausgeströmten Wasserstoff, insbesondere während und/oder nachdem das Kraftfahrzeug in die Überkopf-Position überführt wird/wurde.

The technology disclosed herein relates to a method for checking the tightness of a hydrogen-carrying motor vehicle, which may also be referred to as a method for detecting hydrogen leakage from a hydrogen-carrying motor vehicle. The method comprises the steps:

• - Transfer of the motor vehicle from a use position of the motor vehicle in an overhead position of the motor vehicle, wherein the motor vehicle may be surrounded at least during the transfer of a hydrogen-tight housing; and
• Detecting hydrogen flowing out of the motor vehicle, in particular during and / or after the motor vehicle has been transferred to the overhead position.

These steps describe a method for detecting hydrogen. If no hydrogen is detected, then it can be assumed that the motor vehicle has no leakage. However, if hydrogen is detected, there is a risk that the motor vehicle is not tight. The corresponding vehicle can then be examined in more detail for leaks. For this purpose, for example, other integrative or local methods can be used. For example, the hydrogen-carrying components can be checked for leakage with a leak-detection spray.

A hydrogen-carrying motor vehicle can be any motor vehicle in which at least one component that carries hydrogen is installed. For example, the hydrogen-carrying motor vehicle may be a motor vehicle which comprises at least one fuel cell system. The fuel cell system is intended, for example, to provide the energy for at least one drive machine for locomotion of the motor vehicle. A fuel cell system comprises, in addition to the at least one fuel cell, peripheral system components (BOP components) which can be used during operation of the at least one fuel cell.

A hydrogen-tight housing is a housing completely surrounding the motor vehicle, which does not let hydrogen through or only in negligible quantities. The term "hydrogen-tight enclosure" thus also includes enclosures which have a negligible hydrogen permeation rate. A negligible hydrogen permeation rate in the present case is a permeation rate which is so low that it does not influence the detection of hydrogen or only insignificantly. Expediently, hydrogen present within the enclosure is detected. The use position of the motor vehicle is the position in which the motor vehicle (especially after completion or a repair) is aligned for driving use, ie i.d.R. "On all four wheels", if wheels are mounted. In other words, the use position is a starting position GP of the motor vehicle, in which the motor vehicle roof is arranged higher than the door sill.

As a rule, the construction position of the motor vehicle is the use position. However, the motor vehicle can also be arranged deviating from the horizontal starting position in an inclined starting position, which is also still to be regarded as a use position. In such a horizontal or moderately inclined starting position, escaping hydrogen would continue to accumulate in the cavities.

The overhead position of the motor vehicle is in particular the position in which hydrogen trapped in the cavities can at least partially (preferably completely) escape from the cavity due to gravity or buoyancy upwards. The positional angles which define and thus define the overhead position depend on the geometry of the cavities: if the vertical direction is reversed, then the overhead position corresponds to the amount of all vehicle positions requiring at least partial (preferably complete) emptying (= "dumping ") Cause of liquid-filled cavities. The motor vehicle is thus essentially turned upside down. In particular, the overhead position of the motor vehicle may be the position in which at least one (preferably both) door sill is arranged higher than at least one region of the motor vehicle roof.

The technology disclosed herein may include the step of holding and / or panning the motor vehicle in the overhead position for at least 5 seconds, more preferably at least 20 seconds or 60 seconds.

The technology disclosed herein further includes the step of bringing the vehicle back to the use position. Further preferably, the technology disclosed herein may include the step of transferring the automobile several times to the overhead position and back to the use position.

Alternatively or additionally, the method disclosed herein may include the step of transferring the motor vehicle to the overhead position by rotating and / or pivoting the motor vehicle about an axis of rotation becomes. Preferably, the motor vehicle is rotated about several axes, in particular the motor vehicle longitudinal axis and / or motor vehicle transverse axis.

Preferably, the method disclosed herein may include the step of attaching the motor vehicle to an apparatus for pivoting and / or rotating the motor vehicle prior to transferring the motor vehicle to the overhead position. Preferably, the apparatus is a multi-axis pivoting or multi-axis turning device. Preferably, the device for pivoting and / or turning is integrated in a production line.

Suitably, the motor vehicle during pivoting and / or turning on the wheels, on the wheel suspension, in particular the wheel hub or the wheel attachment, and / or be held on the axles of the motor vehicle.

The technology disclosed herein further includes the method whereby the enclosure is pivoted and / or rotated together with the motor vehicle. Suitably, the housing and the motor vehicle can be coupled together and / or decoupled to a device for pivoting and / or rotating.

Alternatively or additionally, the method disclosed here may include the step of generating a gas flow around the motor vehicle and / or flowing through the motor vehicle within the hydrogen-tight enclosure. A gas flow flowing around the motor vehicle is a gas flow which is guided along or flows along the outer skin of the body of the motor vehicle. A gas flow flowing through the motor vehicle is a gas flow which flows through the motor vehicle, in particular through the front-side cooling openings of the motor vehicle, particularly preferably through the radiator grille. Particularly preferably, the gas flow is an air flow. Particularly preferably, the hydrogen is detected downstream of the motor vehicle. Further preferably, the gas flow can be recirculated. This means that the gas flow flowing away from the motor vehicle is brought again in front of the motor vehicle and the motor vehicle again flows through or flows around. Preferably, a gas conveyor may be provided upstream of the motor vehicle, suitably in front of the motor vehicle. The gas flow may include laminar and / or turbulent regions. The laminar gas flow is well suited to carry escaping gas. The turbulent gas flow is well suited to achieve (for example in front of the detector) a uniform mixing of the hydrogen in the gas flow.

Preferably, the housing is rinsed after checking the tightness. However, it is also conceivable that only the change in the hydrogen concentration is detected, so that a rinse can be omitted.

The housing may advantageously have a hydrogen-tight plastic film and / or hydrogen-tight plastic shell which at least partially surrounds the motor vehicle.

Particularly preferred for motor vehicles with different outer contours different housings can be used. Wherein the contour of the enclosure can be adapted to the outer contour of the motor vehicle. Suitably, the contour of the enclosure is designed so that the volume of the enclosure in which the motor vehicle is located as low as possible. Advantageously, therefore, a particularly small control volume can be created in which even very small amounts of hydrogen can be reliably detected.

The detection of hydrogen present within the enclosure may be within the enclosure and / or outside the enclosure. For this purpose, for example, at least a part of the detection device can be arranged within the enclosure. For example, a detection device with the housing at least temporarily be fluidly connected. It is also conceivable that a gas sample is taken from the housing and a detection device is fed continuously or discontinuously.

For example, a hydrogen sensor or a hydrogen indicative material may be used for detection.

Advantageously, the gas can be evaluated for detection of hydrogen, which accumulates within the enclosure at the highest point or adjacent thereto. The highest point is the point at which ascending hydrogen accumulates due to buoyancy. In one embodiment, a hydrogen sensor or a material indicative of hydrogen may be arranged at this point. A point adjacent to the highest point is a point which deviates only insignificantly from the highest point, for example at most 150 cm, furthermore preferably at most 50 cm or at most 10 cm, and in which the approximately maximum hydrogen concentration can likewise be detected.

Alternatively or additionally, a removal point for a gas sample and / or a connection of the detection device may be provided, preferably at the highest point or adjacent thereto.

Advantageously, a suction device may be provided which sucks gas from the interior of the enclosure. The suction device is preferably arranged at the highest point or adjacent thereto. But it can also be arranged in other places.

The hydrogen detection location can thus be directly a hydrogen detection device or a removal point from which hydrogen is supplied to the hydrogen detection device.

The technology disclosed herein further includes a method of manufacturing a motor vehicle. The tightness of the hydrogen-carrying motor vehicle, in particular of the hydrogen-carrying components, is checked by one of the methods disclosed here. In particular, the tightness of the hydrogen-carrying components of the motor vehicle is checked after the hydrogen-carrying components of the motor vehicle have been mounted. Preferably, the tightness of the hydrogen-carrying components of the vehicle can be checked, preferably before further body components, in particular a door, a hood, a boot lid, and / or a glass pane, are mounted. Advantageously, the entire system can thus be tested on hydrogen-carrying components without unnecessarily hydrogen-blocking cavities being formed by such body components. This further reduces the risk of undetected hydrogen leakage.

Preferably, the technology disclosed herein comprises a method for manufacturing a motor vehicle, wherein the method for checking the tightness of the motor vehicle by a pivoting and / or rotating device, which is integrated into a production line. For example, the swivel hangers commonly used in the automotive industry are suitable for this application.

In the technology disclosed herein, the method comprises detecting hydrogen by means of a device whose lower detection limit is so low that leaked hydrogen can still be detected even when it has been diluted with the air mass present in the enclosure. With the methods disclosed herein, it is possible to collectively provide evidence of hydrogen-tightness. The methods can be used comparatively well in production, in the workshop, in service, in the main inspection, etc. It may be appropriate to dispense with a manual leak detection. The procedures are comparatively fast and safe and work on the entire vehicle. The check can also be more failsafe.

The technology disclosed herein will now be explained with reference to the figures. Show it:

1 a schematic representation of a motor vehicle 10 with cavities 30 ;

2 a schematic representation of a motor vehicle 10 in an enclosure 50 ; and

3 another schematic representation of a motor vehicle 10 in an enclosure 50 ,

The 2 shows a first embodiment of the technology disclosed herein. The enclosure 50 Here is a test room with a roof tapering upwards against the vertical. At the highest point of the enclosure 50 Here is a hydrogen detection site 55 intended. The car 10 is here in the enclosure 50 initially positioned in the use position the GP. Subsequently, the motor vehicle 10 ten around the pivot and / or rotation axis 64 turned. This can be done by turning several axes. The car 10 is rotated and / or panned until it can be assumed that the hydrogen from all cavities 30 could liberate. The hydrogen rises within the enclosure 50 due to its lower density relative to the ambient air against gravity and accumulates at or adjacent to the hydrogen detection site 55 , There, the hydrogen indicative of a leak can be reliably detected. The car 10 can by means of a mounting device 60 to the swivel and / or rotation axis 64 be attached. In this case, the mounting device 60 at the wheel fixings 62 or attack the motor vehicle axles.

Alternatively to the embodiment shown here, in which only the motor vehicle 10 rotates, may also be provided that a to the outer contour of the motor vehicle 10 clinging enclosure 50 as it were with the motor vehicle 10 around the swivel and / or rotation axis 64 rotates. Such a configuration is particularly advantageous for an integration of the method for checking the tightness in a continuous production process. Such a housing 50 can for example with the motor vehicle 10 transported simultaneously on a conveyor belt. Furthermore, this embodiment may have the advantage that the test volume of gas within the enclosure 50 is lower than in the embodiment according to the 2 ,

In other words, the technology disclosed herein relates to a method for checking a hydrogen-carrying motor vehicle with regard to the tightness of the hydrogen-carrying system. Because the cavities 30 in the 1 shown motor vehicle 10 normally prevent hydrogen from rising, becomes the motor vehicle 10 brought into a position according to the technology disclosed here, that the cavities 30 no longer prevent the upgrade to the hydrogen detector. This can be done by the motor vehicle is rotated or pivoted about the longitudinal and / or transverse axis. For this purpose, a mounting device 60 be used on the motor vehicle, for example, at the wheel attachment 62 is locked. The mounting device 60 and the motor vehicle attached thereto 10 are then around the pivot axis 64 pivoted.

The technology disclosed here will now be described with reference to the schematic 3 explained in more detail. The car 10 is here in the enclosure 50 positioned. Upstream of the motor vehicle 10 here is the gas conveyor 70 arranged. The gas conveyor 70 generates a gas flow, which is the motor vehicle 10 flows around or flows through. The car 10 is thus brought into a gas-tight enclosure. A gas conveyor or air winder 70 ensures a sufficient flow around the motor vehicle 10 so that too the cavities 30 be flowed through. The air flow, in the case of hydrogen leakage with hydrogen mixed therein, becomes here at the hydrogen detection site 55 blown past, by means of which the hydrogen contained in the air flow can be detected.

As can easily be seen from the figures shown here, represents the cavity 30 In the methods disclosed here, there is no longer any obstacle to the hydrogen and it can freely escape upwards, where it passes through the gas-tight enclosure 50 to the highest point attached hydrogen detection site 55 is directed. However, the detection can also be carried out by another detection device and with other method steps.

For the sake of legibility, the term "at least one" has been omitted for simplicity. If a feature of the technology disclosed herein is described in singular or undetermined (eg, the / a motor vehicle, the / a hydrogen tank, the / a cavity, the / a use position, the / an overhead position, the enclosure, the / a detection device, the / a mounting device, the / a suspension, the / an axis, the / a gas conveyor, etc.) should be at the same time also their plurality disclosed (eg the at least one motor vehicle, the at least one hydrogen tank, the at least a cavity, the at least one use position, the at least one overhead position, the at least one housing, the at least one detection device, the at least one mounting device, the at least one wheel suspension, the at least one axle, the at least one gas conveyor, etc.).

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

LIST OF REFERENCE NUMBERS

 10

 motor vehicle

20

 Hydrogen tank

 30

 cavity

 GP

 use position

 UP

 Overhead position

 50

 housing

55

 Hydrogen detection site

 60

 mounter

 62

 Arm

64

 axis

 70

 gas producer

Claims (10)

Method for checking the tightness of a hydrogen-carrying motor vehicle, comprising the steps of: - generating a motor vehicle ( 10 ) flowing around and / or the motor vehicle ( 10 ) flowing gas flow within a hydrogen-tight housing ( 50 ); and - detecting from within the enclosure ( 50 ) existing hydrogen. The method of claim 1, wherein the hydrogen downstream of the motor vehicle ( 10 ) is detected.  The method of claim 1 or 2, wherein the gas flow is recirculated.  Method according to one of the preceding claims, wherein the gas flow is guided so that the front-side cooling openings of the motor vehicle, in particular the radiator grille, are flowed through. Method according to one of the preceding claims, wherein in the enclosure ( 50 ) in front of the motor vehicle ( 10 ) a gas conveyor ( 70 ) is provided. Method according to one of the preceding claims, comprising the step of transferring the motor vehicle ( 10 ) from a use position (GP) of the motor vehicle ( 10 ) in an overhead position (UP), wherein the motor vehicle from a hydrogen-tight housing ( 50 ) is surrounded. Method according to one of the preceding claims, wherein the enclosure ( 50 ) a the motor vehicle ( 10 ) at least partially surrounding plastic film and / or plastic shell. Method according to one of the preceding claims, wherein for motor vehicles ( 10 ) with different outer contours enclosures ( 50 ) are used with different contours. A method of manufacturing a motor vehicle, wherein the leak-tightness is tested according to the method of any one of the preceding claims after hydrogen-carrying components of the motor vehicle have been mounted. The method of claim 9, wherein the tightness according to the method of any one of the preceding claims 1 to 8 is checked before body parts, in particular a door, a hood, a luggage compartment door, and / or a glass pane mounted.

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