PISTON FOR A VALVE, ELECTROMAGNETIC VALVE AND FUEL CELL SYSTEM

A piston for a valve configured to control a gaseous medium, the piston including a piston head configured as a closure element and including a seal configured to seal the piston at a valve seat, wherein the seal is arranged at the piston head by a retainer. An electromagnetic valve configured to control a gaseous medium, the electromagnetic valve including an armature; and the piston operatively connected with the armature, wherein the piston head is applicable to the valve seat for closing one or plural pass-through openings of the electromagnetic valve. A fuel cell system including at least one fuel cell stack; a cathode supply; an anode supply; and the electromagnetic pressure regulation valve arranged in the anode supply.

RELATED APPLICATIONS

This application claims priority from and incorporates by reference German application DE 10 2022 114 019.9 filed on Jun. 2, 2022.

FIELD OF THE INVENTION

The invention relates to a piston for a valve for controlling a gaseous medium, an electromagnetic valve for controlling a gaseous medium and a fuel cell system, including the valve.

BACKGROUND OF THE INVENTION

A general configuration for a fuel cell system for a motor vehicle is well known. Fuel cell systems with an anode supply and a cathode supply are also well known. Fuel cell systems use a chemical reaction of a fuel with oxygen into water for generating electrical energy. In order to supply a fuel cell stack of the fuel system with operating agents an anode supply for feeding and extracting the anode operating agent, e.g. hydrogen a cathode supply for feeding and exhausting the cathode operating agents, e.g. air and a coolant loop are provided. The anode and cathode supply respectively include a supply conduit for feeding the operating agent and an exhaust gas conduit. The anode supply furthermore includes a recirculation conduit configured to feed hydrogen included in the anode side exhaust gas of the fuel cell stack back into the fuel cell stack.

The fuel cell system uses various valves for various functions including a pressure regulation valve in the anode supply between a high-pressure range and a medium pressure range.

The automobile industry constantly thrives for economic and functional optimization. Thus, it is an object of the invention to provide an improved piston for a valve for controlling a gaseous medium. Another object of the invention is to provide an optimized electromagnetic valve for controlling a gaseous medium and a fuel cell system configured therewith.

BRIEF SUMMARY OF THE INVENTION

Thus, the object is achieved by the features of claim1. The piston according to the invention for a valve for controlling a gaseous medium, in particular hydrogen includes a piston head configured as a closure element, wherein the piston head includes a seal at a face of the piston head, the seal configured to seal the piston at a valve seat. According to the invention, the seal is arranged at the piston head by a retainer. In known pistons the seals are typically injection molded onto the closure element. This process is complex and time consuming. The invention facilitates replacing this complex process by a simple assembly process.

According to an advantageous embodiment of the invention the seal is arranged in a recess of the piston head and includes a circumferential support portion at a face oriented away from the piston head. The seal can then be mounted by a simple assembly process in the recess of the piston head and attached in the support portion.

Advantageously the support element is configured as a sleeve with a radially inward oriented circumferential protrusion, wherein the sleeve is connected with the piston head by friction locking and the retaining portion of the seal is supported by the protrusion at the piston head. Put differently, the sleeve can be pressed onto the piston head in a simple manner. The seal or the piston head do not require any complex shapes.

According to an advantageous embodiment of the invention the seal can include a central seal portion at a face oriented away from the piston head inside the circumferential retaining portion wherein the sealing portion extends axially beyond the retaining portion. This facilitates a contact at the advantageously annular valve seat and thus sealing when the closure element is closed in a simple manner.

Advantageously the seal includes a center sealing portion at its face oriented away from the piston head and arranged inside the circumferential retaining portion, wherein the sealing portion axially extends beyond the circumferential protrusion of the retainer so that the sealing is assured.

The object is also achieved by an electromagnetic valve for controlling a gaseous medium, in particular hydrogen, the electromagnetic valve comprising a magnetic armature and a piston operatively connected with the magnetic armature wherein the piston head is applicable to a valve seat to close one or plural pass-through openings of the valve.

According to another advantageous embodiment the valve is configured as a pressure regulation valve.

The object is also achieved by a fuel cell system including at least one fuel cell stack, a cathode supply and an anode supply and a pressure regulation valve arranged in the anode supply.

The subsequent detailed description of the invention and the patent claims define further advantageous embodiments and features of the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a view of a known fuel cell system of a vehicle, in particular of an electric vehicle including an electric traction motor which is supplied with electric energy by the fuel cell system1.

The fuel cell system1includes a fuel cell stack2which is typically configured as a stack of PEM-fuel cells. A cathode supply30for feeding and exhausting a cathode operating agent, e.g. air is associated with a common cathode cavity3and an anode supply40for feeding and exhausting an anode operating agent, e.g. hydrogen is associated with a common anode cavity4.

The cathode supply30includes a cathode supply conduit31which feeds air pulled from ambient to the common cathode cavity3of the fuel cell stack2. A cathode exhaust conduit32exhausts cathode exhaust gas from the cathode cavity3. Optionally the cathode exhaust gas is fed to a non-illustrated exhaust system.

The anode supply40includes an anode supply conduit41which provides the anode operating agent, in particular hydrogen from a hydrogen tank43to the anode cavity4. The anode supply conduit41typically includes a pressure control valve49, a tank valve50, a dosing valve51and a cut off valve52. An anode exhaust gas conduit42exhausts anode exhaust gas from the anode cavity4. The anode supply40furthermore includes a recirculation conduit44configured to feed hydrogen included in the anode exhaust gas of the fuel cell stack2back into the fuel cell stack2through a recirculation device45, e.g. a recirculation blower.

Furthermore, the anode exhaust gas conduit41includes a water precipitator46including a downstream drain valve47configured to drain product water generated by the fuel cell reaction and a purge valve48configured to drain the anode gasses, mostly nitrogen.

FIG.2shows an exemplary pressure regulation valve49configured as an electromagnetic proportional valve and arranged between a high-pressure portion and a medium pressure portion of the anode supply40.

The pressure control valve49includes an electromagnetic drive53including a magnetic armature54that is received axially movable in a pole cap57by a magnet coil55including the armature54. A synthetic material housing56envelopes the magnet coil55at an outer circumference and at least at one face wherein the housing56is attached and sealed at a valve housing58. The pole cap57can be integrally configured in one piece and includes a pole core and a pole tube in axial sequence, which however can also be configured as discrete and separate elements.

A piston60operatively connected with the armature54includes a piston head61configured as a closure element and applicable to a valve seat63for closing one or plural pass-through openings62. The illustrated embodiment includes a pass-through opening62integrally configured in one piece with the valve seat63. This pass-through opening62connects a pressure connection P with an outlet A of the valve body58.

As evident fromFIG.2the pressure control valve49is closed in a condition where no electricity flows and the piston head61of the piston60is pressed against the valve seat63since the armature54is pressed towards a closed position by the compression spring64. When the magnet coil55is provided with current, the armature54moves upward in the illustrated embodiment, this means in the opening direction so that the pass-through opening62is opened as a function of the electrical current and the pressure connection P is connected with the outlet A.

FIG.3illustrates a cross section of the piston60. The disc shaped piston head61includes a seal65at a face of the piston head configured to seal the piston60at the valve seat63. Thus, the seal65is arranged at the piston head61by a retainer69. In known pistons the seals are typically injection molded onto the closure element. This process is complex and time consuming. The invention replaces this complex process with a simple assembly process.

It is evident that the seal65is arranged in a recess67of the piston head1and includes a circumferential retaining portion68at a face oriented away from the piston head so that the seal65can be mounted in the recess67of the piston head61by a simple assembly process and attached in the retaining portion68.

The retainer69that is configured as a sleeve with a radially inward oriented circumferential protrusion70is connected form locking with the piston head61so that the retaining portion68of the seal65can be retained at the piston head61by the protrusion70. As evident in particular fromFIG.4showing a blown-up detail Z of the piston60the sleeve is pressed onto the piston head61with a cylindrical wall71.

The seal65includes a center sealing portion72at a face oriented away from the piston head61within the circumferential retaining portion68wherein the central sealing portion72extends axially beyond the retaining portion68and the circumferential protrusion70of the retainer69. This achieves the contact at the advantageously annular valve seat in a simple manner and thus reliable sealing when the closure element is closed.

Since a thickness of the seal65in the retaining portion68is narrower than or identical to a recess depth of the recess67, thus forming an air gap between the protrusion70and the retaining portion68, the sleeve69can be pressed into contact with the piston head61, so that the seal65can be arranged in the piston head61without deformation.

All features described and shown in the individual embodiments of the invention can be used in various combinations when practicing the invention in order to achieve their advantageous effects. The spirit and scope of the invention is defined exclusively by the patent claims and is not limited by the features provided in the description or shown in the drawing figures.