WO2023066619A1

WO2023066619A1 - Jet pump module for a fuel cell system, fuel cell system

Info

Publication number: WO2023066619A1
Application number: PCT/EP2022/076778
Authority: WO
Inventors: Michael Kurz
Original assignee: Robert Bosch Gmbh
Priority date: 2021-10-18
Filing date: 2022-09-27
Publication date: 2023-04-27
Also published as: DE102021211733A1

Abstract

The invention relates to a jet pump module (1) for recirculating anode gas in an anode circuit of a fuel cell system, comprising a first propelling nozzle (2) and a second propelling nozzle (3) which is arranged parallel to the first propelling nozzle (2). The two propelling nozzles (2, 3) are arranged downstream of a common hydrogen metering valve (4) for supplying hydrogen and a control module (5) for switching between a first supply path (6) paired with the first propelling nozzle (2) and a second supply path (7) paired with the second propelling nozzle (3) so that the two propelling nozzles (2, 3) can each be individually operated. The invention additionally relates to a fuel cell system comprising a jet pump module (1) according to the invention.

Description

Title:

Jet pump module for a fuel cell system, fuel cell system

The invention relates to a jet pump module for recirculating anode gas in an anode circuit of a fuel cell system. Furthermore, a fuel cell system with a jet pump module according to the invention is proposed.

State of the art

Hydrogen-based fuel cells require hydrogen and oxygen to convert them into electrical energy, heat and water. The hydrogen is fed to an anode via an anode circuit. The air, which serves as the oxygen supplier, reaches a cathode via an air system. The two gas spaces within a fuel cell are each separated from one another by an electrolyte membrane that is permeable to protons.

A mobile fuel cell system is usually operated with an excess of hydrogen (lambda > 1). The excess hydrogen is recirculated via a recirculation path of the anode circuit and fed back to the fuel cells. The recirculation can be effected actively and/or passively, a recirculation pump being used for active recirculation and a jet pump with a propulsion nozzle being used for passive recirculation. Since a single jet pump can only inadequately cover the entire load range of a fuel cell system, concepts are known from the prior art that use two jet pumps or propulsion nozzles connected in parallel. In order to be able to operate these independently of each other depending on the load, a hydrogen metering valve is connected upstream of each driving nozzle. The respective propulsion nozzle is activated by opening the hydrogen metering valve. However, the combination of two driving nozzles and two hydrogen metering valves increases the space requirement and the costs. The present invention is therefore concerned with the task of specifying a jet pump module with two driving nozzles to cover the largest possible load range, which can be implemented more compactly and at the same time more cost-effectively.

To solve the problem, the jet pump module with the features of claim 1 is proposed. Advantageous developments of the invention can be found in the dependent claims. Furthermore, a fuel cell system with a jet pump module according to the invention is specified.

Disclosure of Invention

The jet pump module proposed for the recirculation of anode gas in an anode circuit of a fuel cell system comprises a first driving nozzle and a second driving nozzle arranged parallel to the first driving nozzle, with the two driving nozzles having a common hydrogen metering valve for supplying them with hydrogen and a control module for switching between a first supply path assigned to the first driving nozzle and a second supply path assigned to the second driving nozzle, so that both driving nozzles can each be operated individually.

A large load range can be covered with the help of the two parallel arranged propulsion nozzles, which can be operated individually. This applies in particular if the two propulsion nozzles are of different sizes or are designed for different loads. Since both propulsion nozzles are operated with one and the same hydrogen metering valve in the jet pump module according to the invention, installation space and costs can be saved. Instead of a further hydrogen metering valve, only one control module is provided, with the aid of which the supply of hydrogen to the two propellant nozzles can be controlled.

The control module is preferably pressure-controlled, so that no additional actuators are required. That is, the control module can be constructed simply.

According to a preferred embodiment of the invention, the control module has a control housing and a control piston in the control housing for controlling two axially spaced open ungsquer erseh nitte is guided axially displaceable. Depending on the axial position of the control piston, either the first opening cross section or the second opening cross section is released, so that either the first drive nozzle or the second drive nozzle is supplied with hydrogen. For this purpose, the supply paths assigned to the driving nozzles are connected to the opening cross sections. This means that the first driving nozzle is connected to the first opening cross section via the first supply path and the second driving nozzle is connected to the second opening cross section via the second supply path. The hydrogen metered in with the aid of one hydrogen metering valve can thus be fed to the first or the second propulsion nozzle.

The control piston preferably has a central supply bore and two axially spaced outer circumferential circumferential grooves which are connected to the supply bore, so that the central supply bore can be connected to one of the two opening cross-sections via the circumferential grooves, depending on the axial position of the control piston. Depending on the axial position of the control piston, either a first circumferential groove is brought into overlap with the first opening cross section, so that a connection of the first supply path with the central supply bore is established, or the second circumferential groove is brought into overlap with the second opening cross section, so that a connection between the second supply path and the central supply borehole is established via this. Depending on the position of the control piston, the first or the second supply path can thus be connected to the central supply bore.

The central supply hole in turn is preferably connected to an outlet of the hydrogen metering valve, so that the supply hole can be charged with hydrogen. The hydrogen can then be introduced via the central supply hole into the first supply path to supply the first driving nozzle or into the second supply path to supply the second driving nozzle, depending on the position in which the control piston is located. If more hydrogen flows into the central supply well than can flow out via the released supply path, the pressure in the central supply well increases. This has the consequence that on the control piston a pneumatic pressure force acts, which leads to an axial displacement of the piston. The shift causes the control module to switch so that the previously enabled supply path is blocked and the previously blocked supply path is released. Accordingly, the previously active propulsion nozzle is deactivated and the previously inactive propulsion nozzle is activated.

In order to oppose a force to the pneumatic pressure force, it is also proposed that the control piston be prestressed in the direction of a stop with the aid of a spring. The stop defines an end position of the control piston in which a connection is made between the central supply bore and one of the two supply paths, so that the recirculation of hydrogen is ensured with the aid of the propulsion nozzle assigned to the supply path. To switch from this driving nozzle to the other driving nozzle, the pressure in the central supply hole must then be increased, so that a pneumatic pressure force acts on the control piston, which is able to move the control piston axially against the spring force of the spring. If the pressure in the central supply bore falls again, the control piston can be returned to its initial position, which is predetermined by the stop, with the aid of the spring force of the spring.

When designing the control module, the opening cross sections and circumferential grooves are preferably dimensioned and arranged in such a way that only one circumferential groove can be brought into complete or partial overlap with an opening cross section. In the event of an axial displacement of the control piston, the currently blocked opening cross section is therefore only released when the currently released opening cross section is completely blocked. This means that with an axial displacement of the control piston, the open cross-section of the opening decreases continuously, so that less and less hydrogen can flow out of the central supply bore and the pressure in the central supply bore increases. This means that the opening cross-sections that are only partially released also act as a throttle. In this way, rapid switching can be realized.

The hydrogen metering valve and the control module are advantageously arranged coaxially. This enables a particularly compact arrangement, since the water serstoffdosierventil can be immediately upstream of the control module. The metered-in hydrogen can thus be fed directly to the control module.

Furthermore, it is proposed that the hydrogen metering valve and the control module form a structural unit. The arrangement can then be made even more compact, so that installation space is saved. For example, the outlet of the hydrogen metering valve can be formed through the control housing, so that the hydrogen metering valve meters the hydrogen directly into the control module or into the central supply bore of the control piston.

Ideally, the two propulsion nozzles of the proposed jet pump module are designed for different system loads. The smaller of the two motive nozzles can then be activated at low loads and the larger of the two motive nozzles at high loads. In this way, the entire load range can be covered with the help of the jet pump module.

Further preferably, the two propulsion nozzles each open into a mixing tube. The freshly metered hydrogen and the recirculated anode gas mix in the mixing tube. For this purpose, each mixing tube has a connection to the anode circuit, via which the recirculated anode gas reaches the mixing tube. The two mixing tubes are preferably also designed for different levels of system loads, the mixing tube designed for higher loads being assigned to the motive nozzle designed for higher loads and the mixing tube designed for lower loads being assigned to the motive nozzle designed for lower loads.

On the outlet side, the two mixing tubes can be brought together again or connected to a supply line, via which the freshly metered hydrogen and the recirculated anode gas can be fed to a fuel cell. Preferably, the two mixing tubes are each connected to the supply line via a non-return valve, so that--in particular when the propulsion nozzle is inactive--no anode gas flows back from the supply line into the respective mixing tube.

Since the preferred area of application of a jet pump module according to the invention is a fuel cell system, a fuel cell system is also used proposed with an anode circuit in which a jet pump module according to the invention is integrated. The space requirement can be reduced due to the compactness of the jet pump module. Furthermore, the cost can be reduced.

Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings. These show:

1a) shows a schematic longitudinal section through a first jet pump module according to the invention with the first propulsion nozzle active and the second propulsion nozzle inactive,

Fig. lb) the control module of Fig. la) in an enlarged view,

2a) the jet pump module of FIG. la) but with a changed position of the control piston of the control module,

Fig. 2b) the control module of Fig. 2a) in an enlarged view,

Fig. 2c) the control module of Fig. 2a) after switching,

3 shows the jet pump module of FIG. 1a) but with the first propulsion nozzle inactive and the second propulsion nozzle active, and

4 shows a schematic longitudinal section through a further jet pump module according to the invention with the first driving nozzle inactive and the second driving nozzle active.

Detailed description of the drawings

The jet pump module 1 shown in FIGS. 1 and 2 is used for the passive recirculation of anode gas in an anode circuit of a fuel cell system in which the jet pump module 1 is integrated. For this purpose, the jet pump module 1 comprises a first propulsion nozzle 2 and a second propulsion nozzle 3, which are arranged in parallel (see FIG. 1a)). The two propulsion nozzles 2, 3 are each assigned a mixing tube 17, 18, which—similar to the propulsion nozzles 2, 3—are designed for loads of different magnitudes. Depending on the load, one or the other propulsion nozzle 2, 3 are activated, so that the entire load range can be covered. The anode gas recirculated via the driving nozzles 2, 3 is introduced via the mixing tubes 17, 18 and check valves 19, 20 arranged on the outlet side of the mixing tubes 17, 8 into a supply line 21, via which the recirculated anode gas can again be supplied to a fuel cell. In the illustrated embodiment, the first propellant nozzle 2 and the mixing tube 17 are designed for lower loads and the second propellant nozzle 3 and the mixing tube 18 are designed for higher loads.

To activate the propulsion nozzles 2, 3, a single hydrogen metering valve 4 is provided. A control module 5 is also provided in order to feed the hydrogen metered in with the aid of the hydrogen metering valve 4 to the first or the second propellant nozzle 2, 3.

As can be seen in particular from FIG. 1b), the control module 5 comprises a control housing 8, in which a control piston 9 is guided in an axially displaceable manner. The control piston 9 has a central supply bore 12 which can be charged with freshly metered hydrogen. The central supply bore 12 is connected to circumferential grooves 13, 14 of the control piston 9 arranged on the outer circumference, which—depending on the position of the control piston 9—can be brought into overlap with a first opening cross section 10 or a second opening cross section 11 of the control housing 8. The first opening cross section 10 is connected to the first propulsion nozzle 2 via a first supply path 6 . The second opening cross section 11 is connected to the second propulsion nozzle 3 via a second supply path 7 . The widths of the circumferential grooves 13, 14 and their axial distance from one another is adapted to the position and dimensions of the opening cross sections 10, 11 in such a way that only one circumferential groove 13, 14 can be brought into overlap with an opening cross section 10, 11. In FIG. 1b), the control piston 9 is in a position in which the circumferential groove 13 opens up the opening cross section 10, so that hydrogen passes from the central supply bore 12 into the supply path 6. The opening cross section 11 , on the other hand, is blocked, so that no hydrogen can get into the supply path 7 . In this position, the control piston 9 is force-balanced, since there is a force balance between a pneumatic pressure force Fp caused by the pressure in the central supply bore 12 and the spring force Ff of a spring 16 prevails, by means of which the control piston 9 is pretensioned in the direction of a stop 22 (see FIG. 1a)).

If the metering of fresh hydrogen is increased via the hydrogen metering valve, the pressure in the central supply hole 12 and thus the pneumatic pressure force Fp acting on the control piston 9 increases, so that there is no longer a balance of forces and the control piston 9 is displaced axially against the spring force Ff of the spring 16 (see Figure 2a)). With a progressive increase in pressure, which is accelerated by the fact that the circumferential groove 13 no longer completely opens up the opening cross section 10 (see Figure 2b)), but acts as a throttle, the control piston 9 assumes a position in which the opening cross section 10 is completely blocked and the opening cross section 11 is partially released (see Figure 2c)). At this point in time, the control module 5 switches so that the first driving nozzle 2 is no longer supplied with hydrogen via the first supply path 6 , but instead the second driving nozzle 3 is supplied with hydrogen via the second supply path 7 . If the dosing is further increased, the control piston 9 assumes a position in which the circumferential groove 14 is brought into complete overlap with the opening cross section 11, so that this is completely released (see FIG. 3).

In order to prevent a pressure cushion from building up on the spring side of the control piston 9 , a relief bore 23 is provided in the control housing 8 , which in turn is connected to the supply line 21 . In this way essentially only the spring force Ff of the spring 16 has to be overcome in order to move the control piston 9 axially.

FIG. 4 shows a further preferred embodiment of a jet pump module 1 according to the invention. This differs from that of FIGS. 1 and 2 primarily in that the hydrogen metering valve 4 and the control module 5 form a structural unit. In this way, even more installation space can be saved. The hydrogen metering valve 4 has an outlet 15 which is formed by the control housing 8 of the control module 5 so that the outlet 15 is the inlet of the control module 5 at the same time.

Claims

- 9 - Claims

1. Jet pump module (1) for recirculating anode gas in an anode circuit of a fuel cell system, comprising a first motive nozzle (2) and a second motive nozzle (3) arranged parallel to the first motive nozzle (2), the two motive nozzles (2, 3) having a common Hydrogen metering valve (4) for supplying hydrogen and a control module (5) for switching between a first supply path (6) assigned to the first driving nozzle (2) and a second supply path (7) assigned to the second driving nozzle (3) are connected upstream, so that both Propulsion nozzles (2, 3) can each be operated individually.

2. Jet pump module (1) according to claim 1, characterized in that the control module (5) has a control housing (8) and a control piston (9) which is located in the control housing (8) for controlling two axially spaced openings (10th , 11) is guided in an axially displaceable manner.

3. Jet pump module (1) according to Claim 2, characterized in that the control piston (9) has a central supply bore (12) and two axially spaced-apart peripheral grooves (13, 14) on the outer circumference, which are connected to the supply bore (12) so that the central supply bore (12) can be connected to one of the two opening cross sections (10, 11) via the circumferential grooves (13, 14) depending on the axial position of the control piston (9).

4. Jet pump module (1) according to claim 3, characterized in that the central supply bore (12) is connected to an outlet (15) of the hydrogen metering valve (4), so that the supply bore (12) can be charged with hydrogen.

5. jet pump module (1) according to any one of claims 2 to 4, characterized in that the control piston (9) is biased in the direction of a stop (22) by means of a spring (16).

6. Jet pump module (1) according to one of the preceding claims, characterized in that the hydrogen metering valve (4) and the control module (5) are arranged coaxially and/or form a structural unit, with the outlet (15) of the hydrogen metering valve (4) preferably passing through the control housing (8) is formed.

7. jet pump module (1) according to any one of the preceding claims, characterized in that the two driving nozzles (2, 3) are designed for different levels of system loads.

8. Jet pump module (1) according to one of the preceding claims, characterized in that the two propulsion nozzles (2, 3) each open into a mixing tube (17, 18), the two mixing tubes (17, 18) preferably also being for different levels of system loads are designed.

9. Jet pump module (1) according to claim 8, characterized in that the two mixing tubes (17, 18) are connected to a supply line (21) on the outlet side, preferably via a check valve (19, 20).

10. Fuel cell system with an anode circuit, in which a jet pump module (1) according to one of the preceding claims is integrated.