Method for operating a two-stage opening solenoid valve, two-stage opening solenoid valve and fuel gas tank with a two-stage opening solenoid valve

Abstract

The invention relates to a method for operating a two-stage opening solenoid valve (10) with two coaxially arranged valve pistons (1, 2) which are guided in one another for movement and are surrounded by a solenoid coil (3) for opening the solenoid valve (10), so that when the solenoid coil (3) is energized, both valve pistons (1, 2) lie in the magnetic flux (12), wherein the following steps are carried out to determine the position of the two valve pistons (1, 2) during opening: a) Measuring a voltage (U i ), b) temporal integration of the measured induced voltage (U i ) and calculating the chained flux (Ψ) according to the equation Ψ = ∫ U idt c) Comparing the course of the calculated interlinked flux (Ψ) with a characteristic course of the interlinked flux (Ψ ref. ). The invention further relates to a two-stage opening solenoid valve (10) and a fuel gas tank with a solenoid valve (10) according to the invention.

Description

[0001] The invention relates to a method for operating a two-stage opening solenoid valve, particularly in its function as a shut-off valve for a fuel gas tank. Furthermore, the invention relates to a two-stage opening solenoid valve for a fuel gas tank and a fuel gas tank with a two-stage opening solenoid valve.

[0002] The preferred field of application of the invention is fuel cell and / or gas vehicles which are powered by a fuel gas which is stored on board in a fuel gas tank. State of the art

[0003] Mobile fuel gas tank systems are known, with at least one fuel gas tank for storing fuel gas, such as hydrogen or natural gas. The fuel gas tanks are typically designed as high-pressure tanks. A high-pressure tank always requires a shut-off valve to seal the tank tightly when the vehicle is not in use. For safety reasons, the shut-off valve is designed as a normally closed valve.

[0004] DE 10 2021 205 684 A1 discloses, for example, a two-stage opening solenoid valve functioning as a shut-off valve for hydrogen tank systems. This comprises a main valve and a control valve for controlling the main valve. The main valve has a valve piston accommodated in a valve housing for reciprocating movement, which interacts with a valve seat formed in the valve housing. The control valve has a reciprocating control piston arranged coaxially to the valve piston, which interacts with a sealing seat formed in the valve piston to release and close an outlet throttle formed in the valve piston. The movements of the control piston, which are controlled by a solenoid coil, can vary a control pressure in a control chamber that is limited by the valve piston of the main valve. The opening of the main valve can thus be controlled via the control pressure in the control chamber.Spring forces keep the control valve and the main valve securely closed when the solenoid coil is de-energized.

[0005] In a two-stage solenoid valve with a main valve and a control valve, opening the control valve changes the pressure conditions at the main valve, causing it to open as well. In the event of a fault, for example, due to a jam, the main valve cannot open or cannot open completely. This must be detected. The present invention addresses this problem.

[0006] This object is achieved by the method having the features of claim 1 and the solenoid valve having the features of claim 6. Advantageous developments of the invention can be found in the respective subclaims. Furthermore, a fuel gas tank with a solenoid valve according to the invention is specified. Disclosure of the invention

[0007] A method is proposed for operating a two-stage opening solenoid valve with two coaxially arranged valve pistons that are guided within each other for stroke movement and surrounded by a solenoid coil to open the solenoid valve. When the solenoid coil is energized, both valve pistons are in the magnetic flux. The following steps are performed to determine the position of the two valve pistons during opening: a) Measuring a voltage U induced by the movement of the valve pistons i , b) temporal integration of the measured induced voltage U i and calculating the linked flux Ψ according to the equation Ψ=∫Uidt c) Comparing the course of the calculated interlinked flux Ψ with a characteristic course of the interlinked flux Ψ stored as a characteristic curve ref. .

[0008] The position of the two valve pistons determined using the proposed method indicates whether the solenoid valve was successfully opened. Upon successful opening, the interlinked flow exhibits a characteristic curve. This can be determined in advance and stored as a characteristic curve, serving as a reference for the comparison to be made in step c).

[0009] The procedure requires that both valve pins of the solenoid valve are in the magnetic flux when the solenoid coil is energized. A two-stage opening solenoid valve suitable for performing the procedure is specified below.

[0010] When carrying out the method in step c), the number and / or position of kinks in the respective course of the interlinked flow is / are preferably compared. If two valve pistons move relative to one another, the number of kinks should also be two. If the course of the calculated interlinked flow has two kinks, both valve pistons have moved. If no kinks occur, neither valve piston has moved. If there is only one kink, only the first stage of opening could be achieved. This means that the inner valve piston has moved, but not the outer one. If the course has more than two kinks, this is an indication that the solenoid valve is jammed or is not working reliably.

[0011] Furthermore, in step c), the maximum value of the calculated chained flow Ψ is preferably compared with the maximum value of the stored chained flow Ψ ref, compared. If the maximum values match, the solenoid valve is fully open or the outer valve piston has reached a stroke stop.

[0012] Furthermore, it is proposed that the position of the two valve pistons determined according to the proposed method be output to a control unit as a CAN ("Controller Area Network") signal via a control unit for controlling the solenoid coil. This is particularly important if the determination of the position has shown that the solenoid valve could not be opened or could not be opened completely. This may require regulatory intervention. This can then be done, for example, with the help of the control unit. Since the solenoid valve can be, in particular, a shut-off valve of a fuel gas tank through which a fuel cell system can be supplied with fuel gas, failure of the solenoid valve to open can impair the fuel supply to the fuel cell system. The control unit to which the CAN signal is output can therefore be, in particular, a control unit of a fuel cell system.Analogously, it can be an engine control unit if the fuel gas tank containing the solenoid valve serves to supply fuel gas to a gas engine of a gas vehicle.

[0013] Since the integration of the induced voltage U i is computationally complex and requires a lot of computing power, the proposed method for determining the position of the two valve pistons of the solenoid valve is preferably only carried out during certain operating phases. This frees up computing power that can be used for other tasks.

[0014] According to a preferred embodiment of the invention, the solenoid valve is a shut-off valve for a fuel gas tank, through which a vehicle can be supplied with fuel gas. In this case, the solenoid valve is opened to extract fuel gas from the fuel gas tank, and steps a) to c) for determining the position of the two valve pistons are preferably performed only when the vehicle is started and / or shut down. This ensures that the vehicle's operation is not impaired.

[0015] Furthermore, a two-stage opening solenoid valve with two coaxially arranged valve pistons is proposed. The valve pistons are guided within each other for stroke movement and are surrounded by a solenoid coil for opening the solenoid valve, so that when the solenoid coil is energized, both valve pistons are exposed to the magnetic flux. The outer valve piston has a sealing body, which interacts at one end with a sealing seat on the housing and at the other end forms a sealing seat for the inner valve piston.

[0016] The proposed solenoid valve is particularly suitable for implementing the method according to the invention described above, or can be operated according to this method. Thus, the same advantages can be achieved. In particular, the position of the valve pistons can be determined when the solenoid valve opens, so that it can be determined whether the solenoid valve is actually open. This is because both valve pistons must move – at different times – to open.

[0017] The proposed solenoid valve is suitable for implementing this method because both valve pistons are located in the magnetic flux when the solenoid coil is energized. This is ensured in the proposed solenoid valve by the fact that the valve pistons are guided within each other for stroke movement, i.e., they are arranged one inside the other, and thus both are surrounded by the solenoid coil. This, in turn, requires a certain length of the outer valve piston.

[0018] According to a preferred embodiment of the invention, the sealing body of the outer valve piston is made of an elastomer material and is penetrated by an axial bore to form the sealing seat for the inner valve piston. The design of the sealing body from an elastomer material increases the tightness of the solenoid valve, particularly when the solenoid valve is a gas valve or is used to extract fuel gas from a fuel gas tank. The axial bore penetrating the sealing body preferably forms a throttle point or has a throttle point. The opening of the inner valve piston in the first stage can thus be effected with little force. Only in the second stage, with the opening of the outer valve piston, is a sufficiently large cross section opened for the extraction of fuel gas.

[0019] The outer valve piston is preferably designed as a hollow piston so that it can accommodate the inner valve piston. Furthermore, the outer valve piston is preferably composed of a base body that accommodates the sealing body and a sleeve that extends the base body. The multi-part design of the outer valve piston facilitates the production and assembly of the solenoid valve. The sleeve allows the required length of the outer valve piston to be easily achieved.

[0020] Since the solenoid valve is particularly suitable as a shut-off valve for a fuel gas tank, a fuel gas tank with a solenoid valve according to the invention is further proposed. The solenoid valve is preferably integrated, together with at least one other valve, into a tank unit connected to the fuel gas tank. The tank unit can also contain other components, for example, filters, sensors, and the like. drawing

[0021] The invention and its advantages are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic longitudinal section through one half of a first and a second solenoid valve according to the invention, Fig. 2 a diagram for graphically representing the course of the concatenated flux as a function of the current and Fig. 3 a flow chart to explain a preferred method sequence for determining the position of the valve pistons during the opening of the solenoid valve. Detailed description of the drawings

[0022] In the Fig. 1, the left half shows a first two-stage opening solenoid valve 10 according to the invention, and the right half shows a second two-stage opening solenoid valve 10 according to the invention. Both solenoid valves 10 each have two coaxially arranged valve pistons 1, 2 that are guided within one another for stroke movement. The outer valve piston 1 of the second solenoid valve 10 (right half), in contrast to the outer valve piston 1 of the first solenoid valve 10 (left half), is composed of a base body 1.1 and a sleeve 1.2. Otherwise, both solenoid valves 10 are essentially identical in design, so that they are described below as one solenoid valve 10.

[0023] The outer valve piston 1 is designed as a hollow piston and has a sealing body 4 made of an elastomer material at one end. This interacts with a sealing seat 5 formed by a valve housing 9. The sealing body 4 is penetrated by an axial bore 7 to form a sealing seat 6 for the inner valve piston 2. To open the solenoid valve 10, a solenoid coil 3 is provided, which surrounds both valve pistons 1, 2 so that, when the solenoid coil 3 is energized, both valve pistons 1, 2 are located in the magnetic flux 12. The closing of the solenoid valve 10 is effected by means of a spring 8, which is supported on the inner valve piston 2. During closing, the inner valve piston 2 presses the outer valve piston 1 into the sealing seat 5 on the housing side.

[0024] The solenoid valve 10 is presently integrated into a tank unit 11, via which the solenoid valve 10 can be connected to a fuel gas tank (not shown).

[0025] When opening the solenoid valve 10, it is important to ensure that the solenoid valve 10 is actually open, i.e., that both valve pistons 1, 2 have moved – with a time offset. With this movement, the valve pistons change their position relative to the solenoid coil 3, so that the movement induced voltage U i This is exploited by the method according to the invention, which is described below with reference to Fig. 3 is explained.

[0026] During the opening of the solenoid valve 10, the voltage U induced by the movement of the valve pistons 1, 2 i measured (step S1). The time integration of the induced voltage U i provides the linked flux Ψ as a function of the current I (step S2). The course of Ψ is compared with a reference value P ref. Compared (step S3), which is stored, for example, as a characteristic curve in a control unit 14. A characteristic curve is shown, for example, in the Fig. 2. If two kinks 13 occur (see Fig. 2), both valve pistons 1, 2 have moved. Reaching an upper stop can be determined based on the maximum flow. The position of the valve pistons 1, 2 determined in this way can then be transmitted, for example, as a CAN signal, to a higher-level control unit (step S4). If the induced voltage Ui ≠0 (step S5), the measurement is repeated or step S1 is started again. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 205 684 A1

[0004]

Claims

[1] Method for operating a two-stage opening solenoid valve (10) with two coaxially arranged valve pistons (1, 2), which are guided in one another for movement and are surrounded by a solenoid coil (3) for opening the solenoid valve (10), so that when the solenoid coil (3) is energized, both valve pistons (1, 2) lie in the magnetic flux (12), wherein the following steps are carried out to determine the position of the two valve pistons (1, 2) during opening: a) Measuring a voltage U induced by the movement of the valve pistons (1, 2) i ), b) temporal integration of the measured induced voltage (U i ) and calculating the chained flux (Ψ) according to the equation Ψ=∫Uidt c) Comparing the course of the calculated interlinked flux (Ψ) with a characteristic course of the interlinked flux (Ψ ref. ). [2] Method according to claim 1, characterized bythat in step c) the number and / or position of kinks (13) in the respective course is / are compared. [3] Method according to claim 1 or 2, characterized by that in step c) the maximum value of the calculated chained flow (Ψ) is compared with the maximum value of the stored chained flow (Ψ ref. ) is compared. [4] Method according to one of the preceding claims, characterized by that the determined position of the two valve pistons (1, 2) is output as a CAN signal to a control unit, for example to a control unit of a fuel cell system, via a control unit (14) for controlling the magnetic coil (3). [5] Method according to one of the preceding claims, characterized bythat the solenoid valve (10) is opened to extract fuel gas from a fuel gas tank via which a vehicle is supplied with fuel gas and steps a) to c) for determining the position of the two valve pistons (1, 2) are only carried out when starting and / or stopping the vehicle. [6] Two-stage opening solenoid valve (10)) with two coaxially arranged valve pistons (1, 2), which are guided in one another for movement and are surrounded by a magnetic coil (3) for opening the solenoid valve (10), so that when the magnetic coil (3) is energized, both valve pistons (1, 2) lie in the magnetic flux (12), wherein the outer valve piston (1) has a sealing body (4) which cooperates at one end with a housing-side sealing seat (5) and at the other end forms a sealing seat (6) for the inner valve piston (2). [7] Solenoid valve (10) according to claim 6, characterized bythat the sealing body (4) is made of an elastomer material and is penetrated by an axial bore (7) to form the sealing seat (6), which bore preferably forms or has a throttle point. [8] Solenoid valve (10) according to claim 6 or 7, characterized by that the outer valve piston (1) is designed as a hollow piston, which is preferably composed of a base body (1.1) receiving the sealing body (4) and a sleeve (1.2) extending the base body (1.1). [9] Fuel gas tank with a solenoid valve (10) according to one of claims 6 to 8, wherein preferably the solenoid valve (10) is integrated together with at least one further valve into a tank unit (11) connected to the fuel gas tank.

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