INJECTION MODULE FOR A SUPPLY UNIT OF A FUEL CELL SYSTEM

Description

Technical area

[0001] The present invention relates to an injection module for a delivery unit of a fuel cell system for conveying and / or recirculating a gaseous medium, in particular hydrogen. State of the art

[0002] Fuel cells are increasingly being used as energy converters, including in vehicles, to convert chemical energy stored in a fuel, such as hydrogen, together with oxygen, directly into electrical energy. Fuel cells typically have an anode, a cathode, and an electrolytic membrane arranged between the anode and cathode. Oxidation of the fuel occurs at the anode, and reduction of the oxygen occurs at the cathode. This produces water on the cathode side.

[0003] Typically, the anode of fuel cells is continuously supplied with excess gaseous fuel—that is, more fuel than would be stoichiometrically required for a given amount of oxygen supplied to the cathode. The excess fuel is usually recirculated or fed back to the anode, particularly via an injection module for a fuel cell system's delivery unit.

[0004] DE 10 2014 225 274 A1 discloses an injection module for a delivery unit of a fuel cell system for conveying and / or recirculating a gaseous medium, in particular hydrogen, with a metering valve. The injection module has a connecting opening and / or an inlet opening through which the gaseous medium flows into the injection module. Furthermore, the injection module has a small nozzle body with a first drive nozzle and a large nozzle body with a second drive nozzle through which the gaseous medium flows out of the injection module. The small nozzle body is arranged in the large nozzle body and / or in the injection module so as to be movable along a longitudinal axis.The small nozzle body and the large nozzle body each have a gas flow path III, IV, whereby the gaseous medium can flow either only through the first gas flow path III or through the first gas flow path III and the second gas flow path IV simultaneously, whereby the second gas flow path IV can be opened or closed by a movement of the small nozzle body. Both drive nozzles are also controlled by a common metering valve, with the second drive nozzle being activated via a spring-loaded connection valve formed by the inner nozzle. This arrangement results in a very simple and compact design of a jet pump with two nozzles and a common metering valve.

[0005] EP 2 242 138 A1 shows a valve unit for regulating the flow of working fluid between a working chamber of a fluid processing machine and both a first and a second working fluid line.

[0006] JP 2006 252863 A discloses a fuel cell reaction gas supply device and fuel cell control device including the reaction gas supply device.

[0007] From US 2017 / 244116 A1 a fuel gas circulation apparatus is known, with a diffuser which is accommodated in a fastening hole of a body, wherein an injector can be connected upstream of the diffuser by means of an attachment.

[0008] The injection module for a delivery unit known from DE 10 2014 225 274 A1 may have certain disadvantages.

[0009] When the metering valve opens, a jet pump pressure from the second motive nozzle develops on the downstream side of the injection module. This jet pump pressure from the second motive nozzle acts on the end faces of a small nozzle body, causing the activation valve to close again, particularly gas flow path IV. This results in a no longer stable activation function of the second motive nozzle. Disclosure of the invention

[0010] According to the invention, an injection module for a delivery unit of a fuel cell system for conveying and / or recirculating a gaseous medium, in particular hydrogen, is proposed. The injection module has a connecting opening and / or an inlet opening through which the gaseous medium flows into the injection module. The injection module has the small nozzle body with a first drive nozzle and a large nozzle body with a second drive nozzle through which the gaseous medium flows out of the injection module. Furthermore, the small nozzle body is arranged in the large nozzle body and / or in the injection module so as to be movable along a longitudinal axis.The small nozzle body and the large nozzle body each have a gas flow path III, IV, wherein the gaseous medium can flow either only through the first gas flow path III or through the first gas flow path III and the second gas flow path IV simultaneously, wherein the second gas flow path IV can be opened or closed by means of a movement of the small nozzle body.

[0011] With reference to claim 1, the injection module is designed such that the small nozzle body bears against a stop disk and / or at least indirectly against the large nozzle body, thus forming an opening pressure surface, wherein the opening pressure surface and a closing pressure surface, located in particular on the downstream side of the small nozzle body, are of equal size, wherein the opening button can be subjected to a dynamic pressure on the upstream side. In this way, the advantage can be achieved that the small nozzle body does not move in the direction of the longitudinal axis towards the stop disk and / or the large nozzle body and come into contact with it in such a way that the flow connection of the second gas flow path IV is closed, and thus only the first gas flow path III is flowed through by the gaseous medium.When the sequence valve opens due to the movement of the small nozzle body, the jet pump pressure of the second drive nozzle is inherently generated on the downstream side. This prevents the downstream jet pump pressure, which acts particularly on the closing pressure surface of the small nozzle body, from causing the small nozzle body to close. Instead, a stable function of such a simple design with a concentric double nozzle can be achieved, achieving stable, pressure-controlled opening of the sequence valve and ensuring that the second gas flow path IV remains stably open even when the jet pump pressure is present. This allows the injection module to reliably supply the hydrogen required by the operating state of a fuel cell in the required quantity.This ensures a stable activation function of the second nozzle and the efficiency of the entire fuel cell system can be increased across different operating states.

[0012] The subclaims relate to preferred developments of the invention.

[0013] According to an advantageous embodiment of the injection module, the small nozzle body is at least nearly cylindrical in the direction of its longitudinal axis. This allows for a compact design of the delivery unit.

[0014] According to a particularly advantageous development of the injection module, the sum of the downstream and upstream end faces of the small nozzle body, excluding the closing pressure surface and the opening pressure surface, are at least virtually equal. This makes it possible to achieve the advantage that when the sequence valve is opened by means of the movement of the small nozzle body and thus the opened second gas flow path IV, the latter can be kept in a stable state, since the sum of the downstream and upstream end faces is at least virtually equal. Thus, with at least approximately equal back pressure and jet pump pressure, a force equilibrium is established on the small nozzle body, preventing it from moving in the direction of its longitudinal axis.This leads to improved efficiency of the injection module and / or the delivery unit and / or the entire fuel cell system. According to an advantageous embodiment of the injection module, the small nozzle body has at least one disc-shaped guide element on its surface facing away from the longitudinal axis, by means of which disc-shaped guide element the small nozzle body is guided in the large nozzle body, in particular orthogonal to the longitudinal axis. In this way, on the one hand, quick and cost-effective assembly can be achieved in that the respective small nozzle body can be inserted into the large nozzle body, in particular in the direction of the longitudinal axis. This reduces the overall costs of the injection module. On the other hand, reliable guidance of the small nozzle body in the large nozzle body can be achieved, so that reliable opening of the connection valve can be achieved over the entire service life of the injection module.In this way, the reliability of the entire fuel cell system can be increased.

[0015] According to a particularly advantageous development of the injection module, the injection module has a spring element, wherein the spring element is located, in particular, in the direction of the longitudinal axis between the large nozzle body and the small nozzle body, and wherein the spring element presses the small nozzle body against the stop disk and / or indirectly against the large nozzle body by means of a spring force. In this way, the advantage can be achieved that the small nozzle body is moved back to a basic position by the spring element as soon as the inflow-side dynamic pressure falls below a certain pressure level, for example, in a low operating state and / or a low power output of the fuel cell and / or a closed metering valve, whereby the second gas flow path IV is closed.This eliminates the components required to return the small nozzle body to its home position on the stop disc and / or the large nozzle body, thereby reducing the complexity of the injection module and thus reducing manufacturing and assembly costs.

[0016] According to a particularly advantageous development, the back pressure in the intermediate space increases continuously when the metering valve is open, while in particular the jet pump pressure downstream of the intermediate space remains at least virtually constant until a switching pressure level is reached at which the pressure force exerted on the opening pressure surface exceeds the spring force and moves the small nozzle body away in the direction of the longitudinal axis such that the valve seat is lifted and a second gas flow path IV opens. In this way, the advantage can be achieved that the small nozzle body is not influenced by the jet pump pressure in a pressure chamber and has a stable opening behavior. The opening function of the sequence valve, in which the second flow path opens for flow, is not dependent on the jet pump pressure and / or back pressure of the second drive nozzle. This ensures a stable switching function of the second drive nozzle.This also allows for continuous adjustment of the dosing quantity to control the pressure in the anode system.

[0017] According to an advantageous embodiment of the injection module, the spring force of the spring element, particularly during movement of the small nozzle body, does not run linearly over the path upon compression or decompression of the spring element, but rather the spring element has a spring constant that progressively changes over the spring path. In this way, the movement path of the small nozzle body can be designed to be adjustable depending on the magnitude of the back pressure, so that a maximum opening path of the small nozzle body is only reached at the greatest possible back pressure. This allows the injection module to be designed to be even better adapted to the operating conditions, which has the advantage of improving the efficiency of the entire delivery unit and / or the fuel cell system.

[0018] According to an advantageous development of the injection module, the spring element has a progressively variable spring constant, which is achieved by varying the coil diameter of the closing spring and / or by the closing spring being constructed from at least two spring segments, wherein the spring segments have different spring constants. This provides the advantage of achieving a compact design of the injection module.

[0019] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of one skilled in the art. Short description of the drawing

[0020] The invention is described in more detail below with reference to the drawing.

[0021] It shows: Figure 1 shows a schematic sectional view of a delivery unit with an injection module, a jet pump and a metering valve, Figure 2 shows a schematic sectional view of the delivery unit with an enlarged view of the injection module, Figure 3 shows a sectional view of the injection module and the metering valve in an enlarged view, Figure 4 shows a schematic representation of a fuel cell arrangement according to the invention with a fuel cell and the delivery unit, Embodiments of the invention

[0022] The representation according to Fig. 1 shows a schematic sectional view of a delivery unit 1 with an injection module 2, a jet pump 4 and a metering valve 10, in particular with a base body 8 of the jet pump 4.

[0023] The jet pump 4 has a first inlet 28, a second inlet 36, a suction area 7, the mixing tube 9, and a diffuser area 11. The metering valve 10 has the second inlet 36 and a nozzle 12, 14. The metering valve 10 is inserted into the jet pump 4, in particular in the direction of a longitudinal axis 52, in an opening in the base body 8 of the jet pump 4. Fig. 1 It is also shown that a medium to be conveyed flows through the conveying unit 1 in a flow direction III. The majority of the flow-through regions of the conveying unit 1 are at least approximately tubular and serve to convey and / or guide the gaseous medium, which is in particular H 2 with proportions of H 2 O and N 2, in the conveying unit 1. The gaseous medium flows through a central flow region 19 in the interior of the base body 8 parallel to the longitudinal axis 52 in the flow direction III, wherein the central flow region 19 begins in the region of the mouth of the nozzle 12, 14 in the suction region 7 and extends through the mixing tube 9 into the diffuser region 11 and, for example, beyond, in particular in a region with an at least almost constant diameter of a flow cross-section of the conveying unit 1.In this case, a recirculate is supplied to the conveying unit 1 through the first inlet 28, wherein the recirculate is in particular the unused H 2 from an anode region 38 (shown in . Fig. 4 ) of a fuel cell 32, in particular a stack, wherein the recirculate can also contain water and nitrogen. The recirculate flows into the valve jet pump arrangement 3 on a first flow path VI. On the other hand, a gaseous propellant medium, in particular H 2, flows through the second inlet 36 on a second flow path VII from outside the delivery unit 1 into an opening of the delivery unit 1 and / or into the base body 8 and / or the metering valve 10, wherein the propellant medium can come from a tank 34 and is under high pressure, in particular of more than 5 bar. The second inlet 36, b runs through the components base body 8 and / or metering valve 10. From the metering valve 10, the propellant medium is discharged by means of an actuator and a fully closable valve element, in particular intermittently, through the nozzle 12 into the intake area 7 and / or the mixing tube 9.The H 2 flowing through the nozzle 12, 14 and serving as the propellant medium has a pressure difference and / or velocity difference to the recirculation medium flowing into the delivery unit 1 from the first inlet 28, wherein the propellant medium has a higher pressure of at least 5 bar in particular. If a so-called jet pump effect occurs, the recirculation medium is conveyed at a low pressure into the central flow region 19 of the delivery unit 1 and at a high velocity, which can in particular be close to the speed of sound, through the nozzle 12, 14 into the central flow region 19 of the intake region 7 and / or the mixing tube 9. The nozzle 12, 14 has an inner recess in the form of a flow cross-section through which the gaseous medium can flow, in particular coming from the metering valve 10 and flowing into the intake region 7 and / or the mixing tube 9.The driving medium encounters the recirculation medium, which is already located in the central flow region 19 of the intake region 7 and / or the mixing tube 9. Due to the high velocity and / or pressure difference between the driving medium and the recirculation medium, internal friction and turbulence are generated between the media. This creates shear stress in the boundary layer between the fast driving medium and the much slower recirculation medium. This stress causes momentum transfer, whereby the recirculation medium is accelerated and entrained. Mixing occurs according to the principle of momentum conservation. The recirculation medium is accelerated in flow direction III and a pressure drop occurs for the recirculation medium, which creates a suction effect and thus pumps additional recirculation medium from the area of the first inlet 28.This effect can be referred to as the jet pump effect. By controlling the metered addition of the propellant medium using the metering valve 10, the flow rate of the recirculation medium can be regulated and adjusted to the respective needs of an entire fuel cell system 31 (shown in ). Fig. 4 ) depending on the operating condition and operating requirements. After passing through the mixing tube 9, the mixed medium to be pumped, which consists in particular of the recirculation medium and the drive medium, flows in flow direction III into the diffuser region 11, whereby a reduction in the flow velocity may occur in the diffuser region 11. From there, the medium flows, for example, further into the anode region 38 of the fuel cell 32.

[0024] Furthermore, the conveyor unit 1 from the Fig. 1 technical features that additionally improve the jet pump effect and the conveying efficiency and / or further improve the cold start process and / or manufacturing and assembly costs. The diffuser region section 11 runs conically in the region of its inner flow cross-section, in particular increasing in the flow direction III. This shape of the diffuser region section 11 can produce the advantageous effect that the kinetic energy is converted into pressure energy, whereby the possible conveying volume of the conveying unit 1 can be further increased, whereby more of the medium to be conveyed, in particular H 2 , can be supplied to the fuel cell 32, whereby the efficiency of the entire fuel cell system 31 can be increased.

[0025] According to the invention, the metering valve 10 can be designed as a proportional valve 10 to enable an improved metering function and more precise metering of the propellant into the intake area 7 and / or the mixing tube 9. To further improve the flow geometry and efficiency of the delivery unit 1, the nozzle 12, 14 and the mixing tube 9 are rotationally symmetrical, with the nozzle 12, 14 extending coaxially to the mixing tube 9 of the jet pump 4 and having at least one internal flow opening 20.

[0026] Fig. 2 shows a schematic sectional view of the delivery unit 1 with an enlarged illustration of the injection module 2. The injection module 2 is suitable for the delivery unit 1 of the fuel cell system 31 for conveying and / or recirculating a gaseous medium, in particular hydrogen. The injection module 2 has a connecting opening 29 and / or an inlet opening 3, through which the gaseous medium flows into the injection module 2, wherein the injection module 2 has a small nozzle body 13 with a first drive nozzle 12 and a large nozzle body 15 with a second drive nozzle 14, by means of which 12, 14 the gaseous medium flows out of the injection module 2. The small nozzle body 13 is arranged in the large nozzle body 15 and / or in the injection module 2 so as to be movable in the direction of the longitudinal axis 52.

[0027] Furthermore, it is shown that the injection module 2 has a spring element 18, wherein the spring element 18 is located in particular in the direction of the longitudinal axis 52 between the large nozzle body 15 and the small nozzle body 13, and wherein the spring element 18 presses the small nozzle body 13 by a spring force against a stop disk 30 and / or indirectly against the large nozzle body 15.

[0028] In addition, Fig. 2 shown that the small nozzle body 13 has at least one disc-shaped guide element 46 on its surface facing away from the longitudinal axis 52, by means of which the small nozzle body 13 is guided in the large nozzle body 15, in particular orthogonal to the longitudinal axis 52. The at least one disc-shaped guide element 46 can have at least one flow opening 16, which is designed, for example, as a bore 16, which runs at least almost parallel to the longitudinal axis 52 through the guide element 46. In the in Fig. 2 In the exemplary embodiment of the injection module 2 shown, the small nozzle body 13 has two disc-shaped guide elements 46.

[0029] Furthermore, Fig. 2 shown that the gaseous medium serving as propellant flows from the tank 34, in which it is under high pressure, for example at least almost 700 bar, to the metering valve 10.

[0030] Fig. 2 shows that the injection module 2 is inserted into the base body 8 of the delivery unit 1, in particular in the direction of the longitudinal axis 52. The injection module 2, for example, with the large nozzle body 15, is in contact with the base body 8, in particular orthogonal to the axis of rotation 52. The large nozzle body 15 has, on the side facing the metering valve 10, the connecting opening 29, by means of which the pressurized gaseous medium flows into an intermediate space 25 in the large nozzle body 15. On its side facing the metering valve 10, the intermediate space 25 of the large nozzle body 15 is at least partially delimited by a housing base 26, which in turn has the connecting opening 29. On its side facing away from the metering valve 10, the intermediate space 25 can be at least partially delimited by the stop disk 30, wherein the stop disk 30 in turn has the connecting opening 29.On its side facing away from the metering valve 10, the large nozzle body 15 has the second drive nozzle 14, wherein the second drive nozzle 14 projects into the suction area 7 and / or the mixing tube 9 of the base body 8.

[0031] In Fig. 3 is an enlarged sectional view of the injection module 2 and the metering valve 10. The gaseous medium is metered into the injection module 2 by means of the metering valve 10, in particular into the intermediate space 25. The injection module 2 consists of the components large nozzle body 15, small nozzle body 13, spring element 18, and the optional stop disk 30. The components are arranged rotationally symmetrically about the longitudinal axis 52. The spring element 18 is supported in the direction of the longitudinal axis 52 on a disk-shaped formation of the small nozzle body 13 and the large nozzle body 15 in such a way that it presses the small nozzle body 13 and / or the injection module 2 and / or the connection valve into a closed position. In this closed position, the small nozzle body 13 forms a valve seat 17 with its end face facing the intermediate space 25 with the large nozzle body 15 and / or the intermediate disc 30.

[0032] In Fig. 2 It is further shown that the injection module 2 and / or the small nozzle body 13 and / or the large nozzle body 15 each have a first and / or second gas flow path III, IV, wherein the gaseous medium can flow either only through the first gas flow path III or through the first gas flow path III and the second gas flow path IV simultaneously. The second gas flow path IV can be opened or closed by means of a movement of the small nozzle body 13. In a basic position, the small nozzle body 13 is at least indirectly in contact with the large nozzle body 15 or the stop disk 30 and thus forms an opening pressure surface 22. The opening pressure surface 22 and a closing pressure surface 24 are at least almost the same size, wherein the closing pressure surface 24 can be acted upon by a downstream jet pump pressure 42 and the opening pressure surface 22 can be acted upon by an upstream dynamic pressure 44.By displacing the small nozzle body 13 in the large nozzle body 15 in the direction of the longitudinal axis 52, the arrangement of the first drive nozzle 12 relative to the second drive nozzle 14 can be changed such that the geometric shape and / or contour of the drive jet in the region of the first and second drive nozzles 12, 14, in particular in the direction of the longitudinal axis 52, of the gaseous medium upon entry into the intake region 7 and / or the mixing tube 9 can be changed. Due to the inventive design of the injection module 2, the pressure surfaces 22, 24 are of almost equal size, so that no resulting pressure surface exists in at least one of the pressure regions in the pressure chamber 27. This is achieved in that a diameter 35 of the valve seat 17 corresponds to an outer diameter 37 of the small nozzle body 13 at the outlet of the first drive nozzle 12 in the intake region 7 or in the region of the mixing tube 9.The small nozzle body 13 is therefore not influenced by the dynamic pressure 42 in a pressure chamber and has a stable opening behavior.

[0033] By means of the inlet opening 3, the gaseous medium can flow from the intermediate space 25, in which the dynamic pressure 44 is present, through the inlet opening 3 to the opening pressure surface 22. From there, the gaseous medium flows either when the connecting valve is closed, in which the small nozzle body 13 is in contact with the stop disc 30, or the large nozzle body 15 in the direction of the longitudinal axis 52 and forms the valve seat 17, only through the first gas flow path III and from there through the first drive nozzle 12.The dynamic pressure 44 in the intermediate space 25 increases continuously when the metering valve 10 is open, while in particular the jet pump pressure 42 downstream of the intermediate space 25 in the region of the pressure chamber 27 remains at least almost the same until a switching pressure level is reached at which the pressure force exerted on the opening pressure surface 22 exceeds the spring force and moves the small nozzle body 13 away in the direction of the longitudinal axis 52 in such a way that the valve seat 17 is lifted and a second gas flow path IV opens.

[0034] When the connection valve is open and the small nozzle body 13 has moved away from the stop disk 30 or the large nozzle body 15 in the direction of the longitudinal axis 52, thus releasing the second gas flow path IV, the gaseous medium flows through the first gas flow path III and the second gas flow path IV. The first gas flow path III opens into the first drive nozzle 12 and the second gas flow path IV opens into the first drive nozzle 12. The first gas flow path III runs through a bore inside the small nozzle body 13 that runs along the longitudinal axis 52. The second gas flow path IV runs through the annular pressure chamber 27 that runs in the direction of the longitudinal axis 52 between the small nozzle body 13 and the large nozzle body 15, wherein the pressure chamber 27 can have a stepped profile.

[0035] Furthermore, Fig. 3 shown that the sum of the resulting downstream pressure surfaces and the resulting upstream pressure surfaces of the small nozzle body 13, with the exception of the closing pressure surface 24 and the opening pressure surface 22, are at least almost the same size. Furthermore, the small nozzle body 13 is designed to be at least almost cylindrical in the direction of the longitudinal axis 52, wherein the small nozzle body 13 has surfaces that run at least almost exclusively parallel or at least almost orthogonal to the longitudinal axis 52, and thus no inclined surfaces on which a pressure level due to the jet pump pressure 42 and / or dynamic pressure 44 can arise. Due to these inventive embodiments of the injection module 2, these end surfaces, with the exception of the pressure surfaces 22, 24, prevent an unforeseen movement of the small nozzle body 13 in the event of pressure fluctuations in the jet pump pressure 42 or the dynamic pressure 44.The disc-shaped guide element 46 has at least one bore extending at least almost parallel to the longitudinal axis 52, so that the gaseous medium can flow in the direction of the second gas flow path IV.

[0036] In the Fig. 3 The spring element 18 shown is characterized in that the spring force of the spring element 18, particularly during a movement of the small nozzle body 13, does not extend linearly over the path during compression or decompression of the spring element 18, but rather that the spring element 18 has a spring constant that progressively varies over the spring travel. The progressively variable spring constant of the spring element 18 is achieved by varying the coil diameter of the closing spring 18 and / or by the closing spring 18 being constructed from at least two spring segments, wherein the spring segments have different spring constants.

[0037] In Fig. 4 An exemplary embodiment of the fuel cell system 31 is shown, in particular of an anode circuit. It is shown that the delivery unit 1 is connected to the fuel cell 32 via a connecting line 33, which comprises the anode region 38 and a cathode region 40. Furthermore, a return line 23 is provided, which connects the anode region 38 of the fuel cell 32 to the first inlet 28, and thus in particular to the intake region 7, of the delivery unit 1. By means of the return line 23, the first gaseous medium not utilized in the anode region 38 during operation of the fuel cell 32 can be returned to the first inlet 28. This first gaseous medium is, in particular, the recirculation medium described above.

[0038] As from Fig. 4As can be further seen, the second gaseous medium stored in the tank 34 is fed via an inflow line 21 to an inflow area, which is designed in particular as the second inlet 36, of the delivery unit 1 and / or the jet pump 4. This second gaseous medium is in particular the propellant medium.

Claims

1. Injection module (2) for a conveying unit (1) of a fuel cell system (31) for conveying and / or recirculating a gaseous medium, in particular hydrogen, wherein the injection module (2) has a connecting opening (29) and / or an inlet opening (3), by means of which the gaseous medium flows into the injection module (2), wherein the injection module (2) has a small nozzle body (13) with a first drive nozzle (12) and a large nozzle body (15) with a second drive nozzle (14), by means of which (12, 14) the gaseous medium flows out of the injection module (2), wherein the small nozzle body (13) is arranged in the large nozzle body (15) and / or in the injection module (2) movably in the direction of a longitudinal axis (52), and wherein the small nozzle body (13) and the large nozzle body (15) each have a gas flow path (III, IV), wherein the gaseous medium can flow either only through the first gas flow path III or through the first gas flow path III and the second gas flow path IV simultaneously, wherein the second gas flow path IV can be opened or closed by means of a movement of the small nozzle body (13), characterized in that the small nozzle body (13) is in contact with a stop washer (30) and / or at least indirectly with the large nozzle body (15) and thus forms an opening pressure surface (22), wherein the opening pressure surface (22) and a closing pressure surface (24), in particular located on the outflow side of the small nozzle body, are of the same size, wherein the opening pressure surface (22) can be loaded with an inflow-side back pressure (44).

2. Injection module (2) according to Claim 1, characterized in that the small nozzle body (13) is of at least almost cylindrical configuration in the direction of the longitudinal axis (52), wherein the small nozzle body (13) has surfaces which run at least almost exclusively parallel or at least almost orthogonally with respect to the longitudinal axis (52).

3. Injection module (2) according to Claim 2, characterized in that the sum of the outflow-side end surfaces and inflow-side end surfaces of the small nozzle body (13), except for the closing pressure surface (24) and the opening pressure surface (22), are at least nearly the same size.

4. Injection module (2) according to Claim 1, characterized in that the small nozzle body (13) has, on its surface facing away from the longitudinal axis (52), at least one disc-shaped guide element (46), by means of which the small nozzle body (13) is guided in the large nozzle body (15), in particular orthogonally with respect to the longitudinal axis (52).

5. Injection module (2) according to one of the preceding claims, characterized in that the injection module (2) has a spring element (18), wherein the spring element (18) is located, in particular, in the direction of the longitudinal axis (52) between the large nozzle body (15) and the small nozzle body (13), and wherein the spring element (18) presses the small nozzle body (13) against the stop washer (30) and / or indirectly against the large nozzle body (15) by means of a spring force.

6. Injection module (2) according to Claim 5, characterized in that the back pressure (44) in the intermediate space (25) increases continuously with an open metering valve (10), while, in particular, the jet pump pressure (42) downstream of the intermediate space (25) remains at least nearly the same until a switching pressure level is reached, at which the pressure force exerted on the opening pressure surface (22) exceeds the spring force and moves the small nozzle body (13) away in the direction of the longitudinal axis (52) in such a way that the valve seat (17) is lifted and a second gas flow path IV opens.

7. Injection module (2) according to Claim 5, characterized in that the spring force of the spring element (18), in particular in the case of a movement of the small nozzle body (13), does not run in a linear manner over the travel during a compression or decompression of the spring element (18), but in that the spring element (18) has a spring constant which is progressively variable over the spring travel.

8. Injection module (2) according to Claim 6, characterized in that the progressively variable spring constant of the spring element (18) is achieved by virtue of the fact that the winding diameter of the closing spring (18) is variable, and / or that the closing spring (18) is constructed from at least two spring segments, wherein the spring segments have different spring constants.