JP2024536128A - Solenoid valve and hydrogen tank system equipped with solenoid valve - Google Patents

Abstract

The present invention relates to a solenoid valve (1), in particular a shutoff valve for a hydrogen tank system, which comprises a solenoid armature (3) accommodated in an armature chamber (2) and a solenoid coil (4) at least partially surrounding the solenoid armature (3), the solenoid armature (3) being guided for stroke movement via a ferromagnetic sleeve (5) that defines the armature chamber (2). According to the invention, the solenoid armature (3) has a number of radially protruding web-like and/or pin-like guide elements (7) for forming a defined radial air gap (6). Furthermore, the present invention relates to a hydrogen tank system comprising a solenoid valve (1) according to the invention.

Description

The present invention relates to a solenoid valve, in particular a shutoff valve for a hydrogen tank system. Furthermore, the present invention relates to a hydrogen tank system comprising a solenoid valve according to the present invention as a shutoff valve.

2. Description of the Related Art In electromagnetic valves with large strokes, such as those applicable to shutoff valves for hydrogen tank systems, solenoid actuators with plunger-type armatures are usually used, since in these actuators the magnetic force does not demagnetize as significantly as in flat armature structures as the spacing between the armature and its immovable stop increases.

DE 10 2018 221 602 A1 discloses, for example, a tank arrangement for storing hydrogen, which comprises an electromagnetically actuable valve arrangement, which has a movable valve element cooperating with a valve seat for opening and closing the outlet opening. The valve element is biased by the spring force of a spring in the direction of the valve seat, so that the valve arrangement is closed when the solenoid coil is not energized. In the open position, the valve element opens the outlet opening with a defined diameter and the flow passage leading to the outlet opening. The valve element simultaneously forms or is connected to a solenoid armature, which works according to the plunger armature principle. When the solenoid coil is energized, a magnetic field is formed which surrounds the coil. The field lines of this magnetic field extend over the pole bodies, the valve housing and the solenoid armature. In DE 10 2018 221 602 A1, the outer sleeve and the inner pole are formed in one piece in a pole body. This pole body includes a sleeve-like section that surrounds the solenoid coil on the outside and directs the magnetic field to the outside of the solenoid coil, and a cover section that closes the solenoid valve above the solenoid armature and forms the inner pole and at the same time a stroke stop for the solenoid armature. In this case, the lines of force run across the axial gap between the solenoid armature and the cover section of the pole body, so that in this gap a force is generated that lifts the solenoid armature or valve element from the sealing seat against the spring force of the spring and moves it axially towards the pole body.

In the valve device of DE 10 2018 221 602 A1, the solenoid armature or valve element is moved in hydrogen. Since the solenoid armature is surrounded by a medium different from air, the armature chamber containing the solenoid armature must be sealed against the coil chamber containing the solenoid coil. Here too, the plunger-type armature structure offers advantages, since for example, as described in DE 10 2018 221 602 A1, a sleeve-like section of the valve housing can be used for sealing. This section simultaneously forms the outer magnetic pole and serves to guide the solenoid armature. Alternatively, a separate sleeve can be used for sealing and guiding the solenoid armature. In this case, this sleeve is usually made of a non-magnetic material, since otherwise the sleeve would form a bypass for the magnetic field, bridging the air gap. The magnetic force is therefore significantly reduced. If a sleeve made of a non-magnetic material is used, it can be considered as a radial air gap with respect to the magnetic field. This air gap is still present when the solenoid armature is in contact with the outer pole body in its upper rest position. This has the advantage that the solenoid armature is prevented from magnetically adhering both to its stroke stop and to the outer pole. Furthermore, the lateral forces acting on the solenoid armature due to the asymmetry are significantly reduced.

However, it has been found that the realization of sealing and guiding via a separate non-magnetic sleeve causes problems when high pressures arise in the armature chamber. In this case, the wall thickness of the sleeve must be designed so that it can withstand the forces that are exerted on the sleeve. The sleeve must therefore have a correspondingly large wall thickness. This wall thickness of the sleeve also increases the radial air gap that it creates and is bridged by the magnetic field. The current required to generate the magnetic field is correspondingly increased. To solve this problem, the sleeve can be made of a ferromagnetic material. In this case, a disk made of a non-magnetic material is inserted between the sleeve and the outer pole body for magnetic separation. This disk must be located between the solenoid armature and the outer pole body at the height of the air gap in the axial direction, so that the magnetic field cannot bypass this air gap via the ferromagnetic sleeve section. If a sleeve-like section of the valve housing is used for sealing and guiding as well as for forming the outer pole, a similar process may be carried out, as illustrated, for example, in DE 10 2018 221 602 A1. However, a drawback with this solution is that the lack of air gap in the attraction state of the solenoid armature leads to a solid magnetic adhesion of the solenoid armature to the outer pole body as well as to the stroke stop. Furthermore, even if the solenoid armature is only slightly axially offset within its guide clearance, lateral forces act on the solenoid armature, which lead to considerable frictional forces and therefore wear in the guide area. Attempts to realize the radial air gap by a larger guide clearance between the solenoid armature and the sleeve would only lead to an even larger axial offset of the solenoid armature and therefore even larger frictional forces in the guide area.

A known solution to reduce these problems is to insert a thin non-magnetic disk between the solenoid armature and the inner pole, which ensures a residual air gap even in the suction state. The geometry of the stroke stop may also be designed in such a way that mechanical contact between the solenoid armature and the inner pole is only achieved on a very small part of the inner pole face. However, these solutions have the disadvantage that the contact surfaces between the solenoid armature and the inner pole, respectively, are very susceptible to wear, since they come into contact with a soft additional component or with a greatly reduced contact surface.

The present invention addresses the problem of providing a solution that does not result in the above-mentioned drawbacks. In particular, it is required to provide a solenoid valve with a solenoid armature capable of stroking that is optimally guided and does not tend to magnetically stick. This solenoid valve is particularly intended to be usable as a shut-off valve for hydrogen tank systems.

To achieve this object, a solenoid valve is proposed having the features of claim 1. Advantageous refinements of the invention can be seen from the dependent claims. Furthermore, a hydrogen tank system comprising a solenoid valve according to the invention is described.

Disclosure of the invention The proposed solenoid valve comprises a solenoid armature accommodated in an armature chamber and a solenoid coil at least partially surrounding the solenoid armature, the solenoid armature being guided for stroke movement via a ferromagnetic sleeve defining the armature chamber. According to the invention, the solenoid armature has a number of radially protruding web-like and/or pin-like guide elements to form a defined radial air gap. The proposed solenoid valve may in particular be a shutoff valve for a hydrogen tank system.

Since the sleeve is made of a ferromagnetic material, it does not form a "radial gap" with respect to the magnetic field. This means that the design of the sleeve's wall thickness based on the required pressure resistance no longer influences the current required to generate the magnetic field. At the same time, however, it is important to prevent magnetic adhesion of the solenoid armature. This is achieved in the proposed solenoid valve in that the "radial gap" is not formed by the sleeve, but by a special configuration of the solenoid armature. For this purpose, the solenoid armature has a number of web- and/or pin-shaped guide elements that protrude radially beyond the actual outer circumferential surface of the solenoid armature, so that, on the one hand, the solenoid armature is guided via the guide elements and, on the other hand, a defined radial gap is formed. In this case, the width of the gap in the radial direction essentially corresponds to the radial excess dimension of the guide elements relative to the actual outer circumferential surface of the solenoid armature. Depending on the outer contour of the solenoid armature, which is recessed from the guide element, the width of the gap can be varied over the entire axial length of the solenoid armature.

When the solenoid coil is energized, a magnetic field is generated. The field lines of this magnetic field first pass from the sleeve to the solenoid armature, preferentially in the region of the guide element. The axial extension of the guide element is preferably selected in such a way that a fraction of the total magnetic flux is already sufficient to magnetically saturate the guide element. In this case, the remaining magnetic flux passes evenly distributed over the entire length of the solenoid armature or sleeve. In this way, a radial air gap is always left, and the radial forces acting on the armature remain extremely small, even in the case of axial offsets within the guide clearance.

In the proposed solenoid valve, the sleeve may be formed as a separate component or may be formed by a housing part of the solenoid valve. In the latter case, the housing part may be an outer sleeve surrounding the solenoid coil or a sleeve engaging in the solenoid coil to form the outer pole of the magnetic circuit. Furthermore, the housing part may be configured to form not only the outer sleeve but also the outer pole arranged inside the solenoid coil. By using the housing part to form the outer pole, it is ensured that this housing part is made of a ferromagnetic material. Furthermore, a separate sleeve for forming the outer pole and the armature guide can be dispensed with. This at the same time eliminates the need for at least one sealing point.

According to a preferred embodiment of the invention, the guide elements are arranged at an axial distance from one another, preferably in the region of the upper and lower ends of the solenoid armature. This arrangement prevents the solenoid armature from tilting, so that the solenoid armature is optimally guided.

To form the guide element, the solenoid armature may have a region with a reduced outer diameter, a grinding on the outer circumferential surface and/or a groove on the outer circumferential surface. In this case, the guide element is formed integrally with the solenoid armature or is a constituent part of the solenoid armature. Depending on the region with a reduced outer diameter, in particular a web-like guide element can be formed which extends over the outer circumferential surface of the solenoid armature. In order to reduce the contact area of this web-like guide element with the sleeve, the guide element may be formed interrupted in the circumferential direction. For the interruption, in particular grindings and/or grooves may be provided.

Alternatively or additionally, it is proposed that the guide element is formed as a separate ring, in particular press-fitted or shrink-fitted, onto the solenoid armature. The guide element thus forms a separate component and may therefore be manufactured from a different material than the solenoid armature. The material selection may in particular be made in relation to the function of the guide element. It is particularly advantageous to manufacture the guide element from a non-magnetic material. In a refinement of the invention, it is proposed that the solenoid armature has at least one cutout for mounting the ring. This cutout reduces the outer diameter of the solenoid armature, so that space is provided for the annular guide element. However, the depth of the cutout is selected to be smaller than the width of the annular guide element in the radial direction, so that the guide element has a radial excess dimension required to form a radial air gap with respect to the solenoid armature. As long as one annular guide element is respectively arranged at the end of the solenoid armature, each end may be provided with a cutout. The guide elements can be supported in the axial direction via radially extending steps that define the cutouts. However, the cutouts at the ends reduce the armature pole surface. Alternatively, therefore, only one cutout may be provided, which extends over substantially the entire axial length of the solenoid armature but maintains a distance to the armature pole surface. Thus, the original size of the armature pole surface continues to be maintained. To maintain a defined axial distance between the guide elements, an intervening sleeve, preferably made of a ferromagnetic material, may be provided. This sleeve is placed, preferably press-fitted or shrink-fitted, on the solenoid armature together with the guide elements in the region of the cutouts.

According to a further preferred embodiment of the invention, the guide elements are formed as separate pins that are partially inserted, in particular pressed, into the solenoid armature. Via this pin, the contact area between the solenoid armature and the sleeve can be further reduced. Since the pin forms a separate component, in this embodiment too, a free material selection, in particular with regard to its magnetic properties, can be made. Preferably, the solenoid armature has at least one radial hole for receiving the pin. This radial hole can be formed as a through hole or as a blind hole. In the latter case, one blind hole is provided for each pin. A pin that protrudes on both sides or two individual pins can be inserted, in particular pressed, into the through hole. If a pin that extends all the way is used, this can be additionally lengthened or calibrated to the correct guide diameter by over-turning or over-grinding. Preferably, the end face used for the guide is provided with a radius. This radius can be adapted in particular to the inner diameter of the outer pole. In the case of pins that protrude only on one side, the guide clearance can be adjusted depending on the press-in depth. The end faces of the pins that serve as guides are preferably rounded. In this case, the rounding can be adapted in particular to the inner diameter of the outer pole.

Advantageously, the guide elements are evenly distributed in the circumferential direction, in particular at equal angular intervals from one another, so that the solenoid armature is guided uniformly. The number of guide elements may be varied.

More preferably, the guide elements are made of a non-magnetic material, so that, from a magnetic point of view, they do not bridge the radial gap between the solenoid armature and the outer pole.

More preferably, a non-magnetic disk is in contact with one end face of the sleeve. This non-magnetic disk is used for magnetic separation between the sleeve and another part of the magnetic circuit. This other part may be, for example, a pot-shaped magnetic pole body or a ferromagnetic cover that defines the armature chamber. In this case, the magnetic pole body or the cover, respectively, forms the inner magnetic pole of the magnetic circuit. The non-magnetic disk is preferably arranged at the height of the axial gap, so that the non-magnetic disk prevents the formation of a bypass surrounding the axial gap.

Furthermore, a hydrogen tank system is proposed, which comprises at least one compressed gas container and a solenoid valve according to the invention for isolating the compressed gas container. In this application, the advantages of the solenoid valve according to the invention are particularly clearly applicable, since the defined radial gap in the guide area of the solenoid armature prevents magnetic adhesion. At the same time, no axial offset of the solenoid armature occurs, since the solenoid armature is optimally guided. Furthermore, hydrogen can be supplied to the armature chamber, since the armature chamber is hermetically sealed by the outer pole formed as a ferromagnetic sleeve. Since the sleeve is made of a ferromagnetic material, the wall thickness of the sleeve can be dimensioned in such a way that a high internal pressure is possible without increasing the current requirement of the magnetic circuit.

Below, a preferred embodiment of the present invention and its advantages are described in detail with reference to the accompanying drawings.

1 is a schematic vertical cross-sectional view of a solenoid valve according to the present invention; 2 is a schematic vertical cross-sectional view of a solenoid armature of the solenoid valve of FIG. 1; FIG. 3 is a possible cross-sectional view of the solenoid armature of FIG. 2; 3 is a possible cross-sectional view of the solenoid armature of FIG. 2; 3 is a possible cross-sectional view of the solenoid armature of FIG. 2; 1 is a schematic longitudinal sectional view of a solenoid armature for a solenoid valve according to the present invention; FIG. 5 is a plan view of the solenoid armature of FIG. 4 . 1 is a schematic longitudinal sectional view of a solenoid armature for a solenoid valve according to the present invention; FIG. 4 is a schematic longitudinal sectional view of another solenoid armature for a solenoid valve according to the present invention.

Detailed description of the drawings The solenoid valve 1 shown in FIG. 1 has an annular solenoid coil 4 acting on a stroking solenoid armature 3 formed as a plunger-type armature. The solenoid armature 3 is accommodated in an armature chamber 2, which is radially bounded by a housing part 8. To guide the solenoid armature 3, the housing part 8 forms a sleeve 5 which separates the armature chamber 2 from a coil receiving chamber 15 in which the solenoid coil 4 is accommodated. This sleeve 5 simultaneously forms the outer pole of the plunger-type armature magnetic circuit. In the axial direction, the armature chamber 2 is bounded by a cover 16, which, like the housing part 8, is made of a ferromagnetic material. This cover 16 forms the inner pole of the magnetic circuit and at the same time a stroke stop for the solenoid armature 3. To magnetically separate the cover 16 from the sleeve 5 forming the outer pole, a non-magnetic disk 14 is inserted between the sleeve 5 and the cover 16.

When the solenoid coil 4 is energized, a magnetic field is formed that has a magnetic force that moves the solenoid armature 3 toward the cover 16, thereby closing the axial gap 19. The return of the solenoid armature 3 after the solenoid coil 4 is de-energized is achieved by the spring 17.

To create a defined radial gap 6, the solenoid armature 3 shown in FIG. 1 has a number of web-like guide elements 7. These guide elements 7 are arranged at an axial distance from one another, so that they are each located at the end of the solenoid armature 3. The guide elements 7 are formed integrally with the solenoid armature 3 (see FIG. 2). As a result, the guiding of the solenoid armature 3 is achieved exclusively via the web-like guide elements 7. The contact area between the solenoid armature 3 and the sleeve 5 is correspondingly reduced.

The web-like guide elements 7 may be formed so as to extend over the entire circumference or may have interruptions in the circumferential direction. As illustrated in FIG. 3a), the web-like guide elements 7 may be interrupted by regions 9 having a reduced outer diameter, so that they each extend over only a partial circumferential region of the solenoid armature 3. In this case, the angular spacing between the guide elements 7 is selected to be equal. Alternatively, the interruptions may be produced by grinding 10. This embodiment is illustrated in FIG. 3b). Another embodiment is shown in FIG. 3c).

The guide element 7 may furthermore be formed by a pin which is inserted, in particular pressed, into at least one radial hole 13 of the solenoid armature 3. This embodiment can be seen in Figs. 4 and 5. The radial holes 13 shown are each formed as through holes and each accommodate one pin. This one pin has an excess length in relation to the radial holes 13 so that it can be inserted, in particular pressed, into the radial holes 13 overhanging on both sides. Instead of one pin, two pins can also be inserted, in particular pressed, into one radial hole 13 from both sides. Depending on the pressing depth, the radial overhang of the pin and thus the radial gap 6 can then be adjusted.

Alternatively or additionally, annular guide elements 7 may be provided. In this case, the solenoid armature 3 preferably has at least one cutout 12 for mounting the annular guide element 7 (see Figs. 6 and 7). In the embodiment of Fig. 6, one cutout 12 is provided at each of the two ends of the solenoid armature 3. In the embodiment of Fig. 7, the solenoid armature 3 has only one cutout 12. However, this cutout 12 extends over a relatively large length of the solenoid armature 3. In this way, the largest possible armature pole surface 18 remains obtained. In order to hold the annular guide elements 7, in particular press-fitted onto the solenoid armature 3 in the region of the cutouts 12, at an axial distance from one another, sleeves 11 are arranged between the guide elements 7. The annular guide elements 7 are preferably made of a non-magnetic material. The sleeves 11 are preferably made of a ferromagnetic material. The radial gap can then be adjusted in the area of the cutout 12 of the solenoid armature 3 according to the outer diameter of the sleeve 11, regardless of the diameter of the solenoid armature 3.

Claims (10)

A solenoid valve (1), in particular a shutoff valve for a hydrogen tank system, comprising:
A solenoid armature (3) housed in the armature chamber (2);
a solenoid coil (4) at least partially surrounding the solenoid armature (3);
The solenoid valve (1), wherein the solenoid armature (3) is guided so as to be capable of stroke movement through a ferromagnetic sleeve (5) that defines the armature chamber (2),
The solenoid valve (1), characterized in that the solenoid armature (3) has a plurality of radially protruding web-like and/or pin-like guide elements (7) so as to form a defined radial gap (6). The solenoid valve (1) according to claim 1, characterized in that the sleeve (5) is formed by a housing part (8). The solenoid valve (1) according to claim 1 or 2, characterized in that the guide elements (7) are arranged at an axial distance from one another, preferably in the region of the upper and lower ends of the solenoid armature (3). The solenoid valve (1) according to any one of claims 1 to 3, characterized in that the solenoid armature (3) has a region (9) with a reduced outer diameter, a grinding portion (10) on the outer circumferential surface side and/or a groove on the outer circumferential surface side to form the guide element (7). The solenoid valve (1) according to any one of claims 1 to 4, characterized in that the guide element (7) is formed as a separate ring that is fitted, in particular press-fitted or shrink-fitted, onto the solenoid armature (3), the solenoid armature (3) preferably having at least one cut-out (12) for mounting the ring. The solenoid valve (1) according to any one of claims 1 to 5, characterized in that the guide element (7) is formed as a separate pin that is partially inserted, in particular pressed, into the solenoid armature (3), and preferably the solenoid armature (3) has at least one radial hole (13) for receiving the pin. The solenoid valve (1) according to any one of claims 1 to 6, characterized in that the guide elements (7) are evenly distributed in the circumferential direction, in particular at equal angular intervals from one another. The solenoid valve (1) according to any one of claims 1 to 7, characterized in that the guide element (7) is made of a non-magnetic material. The solenoid valve (1) according to any one of claims 1 to 8, characterized in that a non-magnetic disk (14) is in contact with one end face of the sleeve (5). A hydrogen tank system comprising at least one compressed gas container and a solenoid valve (1) according to any one of claims 1 to 9 for isolating the compressed gas container.

Images