DE102008029224A1 - Check valve's function i.e. tightness, testing method for fluid pipe in motor vehicle, involves implementing difference pressure-observation by valves during period and controlling observation in no-load operation by control unit - Google Patents

Abstract

The method involves supplying gaseous fluid running from a tank of a consumer e.g. drive unit, of a motor vehicle through a fluid pipe. Difference in pressure-observation is automatically implemented by closed check valves during certain time period of operation of the motor vehicle such that a pipe section guided to the valves is connected with the tank. The difference in pressure-observation is controlled in no-load operation of the consumer's tank by an electronic control unit. The check valves are arranged in series in the fluid pipe.

Description

The invention relates to a method for checking the function of at least one arranged in a fluid line in a motor vehicle shut-off valve, through which line a particular gaseous fluid from a tank to a consumer, in particular the drive unit of the motor vehicle, is supplied, in the broadest sense about a period of time a differential pressure consideration is performed on the closed shut-off valve. The prior art is by way of example on the DE 10 2004 016 378 A1 directed.

Next Motor vehicles containing liquid fuels such as gasoline or diesel are also recent hydrogen powered vehicles on the way. As an escape in particular gaseous hydrogen from the fuel supply system the motor vehicle on the one hand because of lack of practical experience as well on the other hand, in itself in substantially closed rooms (Garage, multi-storey car park) are classified as critical is considered a leakage of gasoline or diesel, the function should be or tightness of shut-off valves in the fluid lines of the Fuel supply system are provided, checked regularly become. Such a functional or leak test of a Shut-off valve can in principle by means of a differential pressure consideration a certain period of time by checking is, if otherwise constant boundary conditions, a pressure gradient over this valve remains unchanged.

In this regard, an advantageous method for checking the Function of at least one in a fluid line in a motor vehicle arranged shut-off valve according to the preamble of claim 1 to show, is an object of the present invention.

The Solution to this problem is characterized in that this differential pressure consideration during the operation of the Motor vehicle in idle mode of the consumer controlled by a electronic control unit automatically several times in a certain time interval is performed.

According to the invention a relatively insensitive, simpler and more feasible so-called Verklemmtest suggested, with which found in the first place can be, whether the shut-off valve ever free is or could possibly be frozen, which in particular in connection with cryogenic in the tank of the motor vehicle stored cryogenic hydrogen could well happen. In this so-called. Jamming test is or will be in idle mode the vehicle user or the consumer in general the or the tank-near shut-off valve (s) is closed for a short time and it is checked whether the pressure in the fluid lines or tank extraction lines, in which this or these shut-off valve (s) is / are provided, then downstream of it or the same drops. (Usually there are two tank-close shut-off valves, namely one for the removal of fluid from the Fuel tank and one for the filling of the Fuel tanks).

If a tank close check valve is leaking, the pressure in the respective Fluid line, eg. In the adjoining the Absperrbventil Withdrawal pipe, do not drop as quickly as in the case of a dense Shut-off valve, as some fluid or hydrogen flow from the tank can. Due to the opening of the valves necessary time, this test is essentially only in idle mode be carried out by the consumer, as at higher Extraction rates of the consumer whose further supply is no longer could be guaranteed. On the other hand, or advantageously however, such a simple test is often done which results in a high security potential, because despite this simple process and continue operation of the possible Consumer recognized almost all safety-critical valve leaks can be.

Around to detect even the smallest leaks in a shut-off valve, can also do a slightly more extensive leak test using a differential pressure view over the shut off valve, due to certain boundary conditions in one ultimately becoming a consumer or Fzg. drive unit leading fluid line or Withdrawal pipe from the tank several shut-off valves arranged in series can be what the test process naturally something more complicated. Because of this series of valves namely, so-called sleeping errors could occur, to the effect that a leaking valve is not recognized because both upstream and downstream thereof Close valve tight. Present is in the sense of a advantageous development thus proposed, either in conjunction with each startup of the motor vehicle or within a predetermined period at least once in a temporal succession for each of the in the fluid conduit or withdrawal conduit serially arranged shut-off valves controlled a differential pressure consideration to perform automatically by an electronic control unit, for which each leading to the check valve to be checked Line section is previously connected to the tank.

there It should be noted that the one used in the preceding paragraph Concept of "commissioning" of the motor vehicle does not mean that the said test is in direct connection or in short temporal relation with a start of the vehicle drive unit or consumer, but that with it just to be expressed that every time the motor vehicle is put into operation after a rest period, for example, only with stopping or parking the motor vehicle the said test is to be carried out. Preferably, this can Test performed only after stopping the motor vehicle be, as - as explained below - in the Within the scope of this test procedure, the previously operated vehicle drive unit is switched off.

One such verification procedure can now be specific proceed as follows: First, the drive unit operated and supplied from the tank, however, the vehicle itself should preferably stand still. Then can an electronic control unit, such as an external diagnostic tester in a service operation, but alternatively also in the vehicle Control unit start the test. Here are by in the Control unit deposited first the tank near shut-off valves closed in the leading out of the tank fluid lines. This causes the drive unit to pressurize the fluid (For example, hydrogen pressure) in the extraction line downstream of the tank near Shut-off valves is lowered, d. H. the drive unit or generally the consumer "sucks the line empty", as long as until the drive unit for lack of further supply to a standstill comes. Are given in this process predetermined time thresholds and / or pressure thresholds hurt, d. H. exceeded or fallen below, so will from this a leak in the tank near shut-off valves closed. Thereafter, the next downstream of the tank near shut-off valves provided shut-off valves closed and it is the downstream pressure the close-to-tank shut-off valves observed. A pressure change indicates for a leak of the same. It is possible even calculate a leakage rate, which at a pressure rise downstream of the close-to-tank shut-off valves from the detected pressure change per Time multiplied by the volume in which this pressure change observed is determined.

in the next process step is a tank close check valve opened, which causes in the line volume between this and the downstream thereof provided second shut-off valve in the Tank prevailing pressure is applied. Downstream of this second shut-off valve on the other hand, in the error-free case, the low pressure, by the suction of the drive unit or consumer has arisen. Then it is through the electronic control unit the detectable by means of suitable sensors pressure upstream and downstream of this second, now closed shut-off valve observed. If a change in the pressure values is detected, then From this closed on a leak. Leave it as already explained above, the leakage rate determine. In the next step is for the third in series shut-off valve analogous to the second proceeded in series shut-off valve.

in principle a leakage of a check valve is thus determined by that a pressure difference is generated over this valve and then checking if it persists or whether the pressure balances in the broadest sense. It can such a detailed review for all valves connected in series only Occasionally, such as in a service center, by an electronic Control unit controlled. Then should for safety reasons, however, be assured that within a given period of, for example, 100 days this review actually carried out becomes. In this sense, in an electronic control unit be provided of the vehicle, that in the case that within the specified period of time to be performed leak test was not performed, a new filling the tank through this electronic control unit on appropriate Way, for example, by not releasing an automatically lockable Tank filling opening, is prevented.

It However, it is also possible to have such a detailed Leak test of valves connected in series at least once during each commissioning (to define this Term, see above) of the motor vehicle or by an electronic control unit provided in the vehicle to have carried out. For this purpose, when parking the vehicle whose drive unit or generally said Consumers will continue to operate a little further to those described above Function to run, with a tracking over a few seconds can be enough. Alternatively could the withdrawal line, in which the to be checked Shut-off valves are provided in the well-known in the art boil-off system a hydrogen tank, the hydrogen in the cryogenic state too save, or be relaxed in the environment. Alternatively, the fact could be used that no Valve is absolutely tight, so while longer Standstill phases of the motor vehicle for the leak test necessary pressure difference also by this quasi natural Leakage and appropriate switching operations of the affected valves can be generated.

With an inventive, carried out automatically by an electronic control unit Thus, the highest level of safety is provided, in particular since human error is ruled out, and this check can advantageously be carried out relatively often and in a simple manner. In particular, this reduces the likelihood or the error rate for sleeping errors (= undetected leak in a valve), wherein it should also be pointed out that quite a number of details can be deviated from the above explanations without departing from the content of the patent claims.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102004016378 A1 [0001]

Claims (3)

Method for checking the function of at least one arranged in a fluid line in a motor vehicle shut-off valve, through which line a particular gaseous fluid is supplied from a tank to a consumer, in particular the drive unit of the motor vehicle, wherein in the broadest sense over a certain period of time Differential pressure consideration is performed on the closed shut-off valve, characterized in that this differential pressure observation is performed automatically during operation of the motor vehicle at a certain time interval in the idle mode of the consumer controlled by an electronic control unit. The method of claim 1 with a leak test for a plurality of shut-off valves arranged in series in the fluid line, characterized in that either in connection with each commissioning of the motor vehicle - possibly afterwards to a stylist of the motor vehicle - or within a predetermined period of time for each of the shut-off valves controlled in time, a differential pressure consideration is carried out automatically by an electronic control unit, what to the check valve to be checked leading line section previously connected to the tank becomes. Method according to claim 2, characterized in that that in the event that within a given time period to be performed leak test not performed was, a new filling of the tank by an electronic control unit of the vehicle is prevented.