CN111502879A - Dual Substance Ejector - Google Patents

Abstract

The invention relates to a dual-substance injector for injecting two different media, which dual-substance injector comprises two coaxially arranged nozzle needles ( 1 , 2 ) which are guided nested within each other for releasing and closing injection openings ( 3 , 4 ), wherein each nozzle needle ( 1 , 2 ) is assigned a control chamber ( 5 , 6 ) that can be charged with a control medium, which can be controlled according to the control valve ( 7 , 8 ) ) is unloaded so that the control pressure acting on the nozzle needles (1, 2) can be changed in order to actuate the corresponding nozzle needles (1, 2). According to the invention, a pressurizing device (10) is arranged in the input path (9) of the first medium, so that the pressure in the input path (9) of the first medium can be increased.

Description

Dual Substance Ejector

technical field

The present invention relates to a dual substance injector. By means of the dual-substance injector, two different media, eg liquid fuel and gaseous fuel or fuel and water, can be injected separately from each other. In the case mentioned by way of example, the injection takes place into the combustion chamber of the internal combustion engine or into the intake system arranged in front of the combustion chamber. For this purpose, the dual-substance injector has two coaxially arranged nozzle needles that are guided in one another for releasing and closing the injection opening.

Background technique

A two-substance injector of the above-mentioned type is known by way of example from the publication DE 10 2016 221 543 A1. Known injectors are used for injecting gaseous and/or liquid fuels into combustion chambers of internal combustion engines. The injector includes a first valve mechanism reciprocally received in the central bore of the nozzle body and a second valve mechanism reciprocally received in the central bore of the first valve mechanism. A control chamber is assigned to each valve mechanism, which can be charged with liquid fuel via an inlet throttle and unloaded via a valve. In order to simplify the construction of the injector, the two valves are connected in series and can be actuated by means of a common actuator. The one actuator reduces the number of components and thus the manufacturing or assembly costs. In this case, the series connection of the two valves also ensures that the two valve mechanisms of the injector can be opened chronologically offset from one another, so that a pilot injection with liquid fuel and a subsequent main injection with gaseous fuel can be performed.

Based on the above-mentioned prior art, a dual-substance injector for a medium supply system, especially a fuel supply system, should be provided, which can reduce the complexity of the system configuration. This relates in particular to fuel supply systems for supplying internal combustion engines with gaseous fuel. In such systems, the complexity is also related to the gas pressure, since high gas pressure affects the thermal balance. Therefore, a low gas pressure is desired from this point of view. However, high gas pressures are required for spraying.

SUMMARY OF THE INVENTION

The task of the present invention is therefore to resolve the above-mentioned conflict of objectives.

To solve this task, a dual substance injector is proposed according to the invention. Advantageous developments of the invention are known from the preferred embodiments.

The proposed dual-substance injector for injecting two different media comprises two coaxially arranged nozzle needles which are guided nested within one another for releasing and closing the injection opening. In this case, each nozzle needle is assigned a control chamber, which can be loaded with a control medium, which can be unloaded depending on the switching position of the control valve, so that the control pressure acting on the nozzle needle can be changed in order to actuate Corresponding nozzle needle. According to the invention, a pressurizing device is arranged in the input path of the first medium, so that the pressure in the input path of the first medium can be increased.

The system pressure can be reduced by a pressure increase inside or near the injector, allowing the selection of less complex system configurations. This applies in particular when the system is a fuel supply system for gaseous fuels (eg natural gas) and liquid fuels. For example, the system may be an NGDI system, where "NGDI" stands for "Natural Gas Direct Injection".

In NGDI systems, the system pressure or the gas pressure required for injection/injection is typically 500 bar. If the pressure is to be provided on the system side, the high gas pressure affects the system configuration since all components must be designed for the high gas pressure. Furthermore, the demands on the thermal balance of the system increase as the gas pressure increases.

If a two-substance injector according to the invention is used in such a system, the gas pressure in the system can be kept low and only raised to the desired value in or near the injector. Accordingly, the complexity of the fuel supply system is reduced. In this case, the first medium is a gaseous fuel or natural gas.

However, the dual mass injector of the present invention is not limited to application as an NGDI injector or as a dual fuel injector. The two-substance injector can also be used in other supply systems for supplying or injecting two different media. As another application example, for example, injection of fuel and water can be cited. The fuel, in particular the gaseous fuel, can also be hydrogen, for example.

Preferably, the proposed booster device for a dual substance injector comprises an intensifier chamber arranged in the input path of the first medium and comprises a piston delimiting the intensifier chamber such that the volume of the intensifier chamber is changeable by the axial position of the piston. If the piston sinks deeper into the intensifier chamber, its volume decreases, which causes the pressure in the intensifier chamber to increase. In this way, the pressure in the feed path of the first medium can be increased.

The input path of the first medium comprises sections inside and outside the injector, so that the pressure increasing device can also be arranged inside or outside the injector. The preferred arrangement is in particular related to the corresponding installation space relationship. If there is insufficient installation space in the injector for receiving the pressurizing device, the pressurizing device can also be arranged outside the injector. In this case, the arrangement is preferably carried out in the vicinity of the injector, in order to avoid possible pressure losses on the way to the injector.

In the case of arranging the pressure increasing device inside the injector, the piston is advantageously arranged in such a way that it moves parallel to the longitudinal axis A of the dual-substance injector, ie parallel to the direction of movement of the two nozzle needles. For example, the piston can be arranged coaxially with respect to the two nozzle needles. In the case where the pressure booster is arranged outside the injector in the vicinity of the injector, the piston can be oriented arbitrarily.

Furthermore, it is proposed that the piston of the pressurizing device at its end facing away from the intensifier chamber delimits a pressure chamber which can be charged with a pressure medium, preferably a control medium. Thus, the pressure in the pressure chamber can be varied and can be used to actuate the piston. Therefore, the axial position of the piston can be changed according to the pressure in the pressure chamber.

以这种方式，可以进一步提高增压，由此增压装置的效率升高。In a development of the invention, it is proposed that the piston is embodied as a stepped piston. That is, the piston comprises sections with different diameters or different piston cross-sections, so that the pressure-charging ratio of the pressure-charging device can be adjusted by means of the corresponding area ratios of the piston cross-sections

In this way, the supercharging can be further increased, whereby the efficiency of the supercharging device increases.

According to a preferred configuration of the invention, the piston of the pressure-increasing device has a first section delimiting the intensifier chamber and a second section delimiting the pressure chamber, the second section having an increased pressure compared to the first section diameter, such that an annular shoulder is constructed that delimits the other pressure chamber. The pressure in the other pressure chamber causes a pressure on the piston which acts against the regulating force in the first pressure chamber. The movement of the piston or the pressure booster can thus be controlled by the pressure difference in the two pressure chambers.

Preferably, the further pressure chamber can be applied to the control medium via the inlet throttle and can be relieved via the outlet throttle as a function of the switching position of the control valve. The coordination of the throttle device is preferably selected such that the control medium flowing into the other pressure chamber is replenished by the continuously open input throttle device than the control medium flowing out of the other pressure chamber through the discharge throttle device with the control valve open. Less control medium. The pressure in the other pressure chamber then drops to such an extent that a resultant force acts on the piston which sinks deeper into the intensifier chamber. Thus, the actuation of the supercharging device can be controlled in a simple manner by the pressures acting on both sides of the piston, respectively.

In order to actuate the two pressure chambers with the control medium, the two pressure chambers are connected to the supply for the control medium. If the control valve controlling the pressure in the other pressure chamber remains closed, the same pressure occurs in both pressure chambers. Therefore, with the control valve closed, the piston is essentially pressure balanced.

Advantageously, the piston of the booster device is supported on a return spring. The return spring facilitates the return of the piston into its initial position. This is especially advantageous when the piston is pressure balanced. The return spring is preferably designed as a compression spring and is accommodated in another pressure chamber.

As an extension, it is proposed that the other pressure chamber of the pressurizing device is connected to the control chamber via a connecting channel for controlling the reciprocating movement of the first nozzle needle. This configuration has the advantage that the control pressure in the control chamber can be controlled via the first nozzle needle, while the pressure in the other pressure chamber of the booster device can be controlled via a common control valve. The structure of the dual-substance injector is correspondingly simplified.

In order to prevent the medium from being sucked back from the further downstream region of the supply path when the piston of the pressure booster is reset and with an accompanying increase in the volume of the intensifier chamber, it is proposed that in the supply path of the first medium, in particular A non-return valve is arranged upstream of the supercharging device, which shuts off against the input direction.

According to an alternative preferred configuration of the invention, the piston of the pressurizing device has a first section delimiting the intensifier chamber and a second section delimiting the pressure chamber, the second section having a reduced pressure compared to the first section The small diameter makes it possible to construct an annular shoulder which delimits another pressure chamber. Contrary to the previous embodiment, the pressure in the other pressure chamber does not oppose the regulating force in the first pressure chamber, but constitutes a pressure balance volume. For this purpose, the other pressure chamber is preferably connected to the return flow for the control medium, so that a return pressure acts in the other pressure chamber. If diesel fuel is used as the control medium, the return pressure is usually no more than 10 bar. The actuation of the piston is thus controlled by the pressure in the first pressure chamber or by the pressure difference between the pressure in the first pressure chamber and the pressure in the intensifier chamber. In order to compress the first medium present in the intensifier chamber, the pressure in the first pressure chamber is increased, so that the piston of the pressurizing device sinks deeper into the intensifier chamber. In order to increase the pressure in the first pressure chamber, the first pressure chamber is charged with a control medium, preferably the same control medium which also controls the reciprocating movement of the nozzle needle.

The input into the first pressure chamber is preferably controlled via a control valve and/or an input throttle. The unloading of the first pressure chamber can be brought about by the discharge throttle and/or the control valve. In this case, only one control valve is required, by means of which either the supply into the first pressure chamber or the discharge from the first pressure chamber can be blocked. In particular, a 3/2-way directional valve or a 3/3-way directional valve is suitable as a control valve. The 3/2-way valve makes it possible to arrange the booster outside the injector. The 3/3 directional valve has the advantage that, depending on the arrangement of the connections to the control chamber formed in the injector, the number of control valves can be reduced overall.

The shoulder formed on the piston of the pressure-increasing device can at the same time form a control edge which, depending on the axial position of the piston, releases or closes the relief path. The unloading path serves to unload the control chamber assigned to the first nozzle needle, so that the control chamber is more quickly unloaded and the first nozzle needle opens more quickly. The connection of the control chamber to the relief path preferably takes place via an outlet throttle associated with the control chamber.

Description of drawings

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The attached figure shows:

Figure 1 is a schematic longitudinal section of a dual substance injector according to a first preferred embodiment,

Figure 2 is a schematic longitudinal sectional view of a dual substance injector according to a second preferred embodiment,

3 is a schematic longitudinal cross-sectional view of a dual-substance injector according to a third preferred embodiment in combination with an injection system,

Figure 4 is a schematic longitudinal cross-sectional view of a dual substance injector according to a fourth preferred embodiment,

Figure 5 is a schematic longitudinal cross-sectional view of a dual substance injector according to a fifth preferred embodiment,

Figure 6 is a schematic longitudinal cross-sectional view of a dual substance injector according to a sixth preferred embodiment,

7 is a schematic longitudinal cross-sectional view of a dual substance injector according to a seventh preferred embodiment and

Figure 8 Schematic diagram of pressure curve and needle stroke curve.

Detailed ways

From the schematic diagram of FIG. 1 , a dual-substance injector according to the invention is known, which can be used, for example, as an NGDI injector. The dual-substance injector has a nozzle body 23 in which two nozzle needles 1 , 2 which are arranged coaxially and are guided within one another are accommodated. The outer nozzle needle 1 controls a first injection opening 3 via which a first medium, eg natural gas, can be injected or blown in. The first nozzle needle 1 is embodied as a hollow needle. The inner nozzle needle 2 controls a second injection opening 4 via which a second medium, such as diesel fuel, can be injected. The inner nozzle needle 2 is received in the outer nozzle needle 1 while forming an input path 24 for the second medium. The outer nozzle needle 1 and the nozzle body 23 together delimit an input path 9 for the first medium.

In the NGDI injector, the inner nozzle needle 2 is first opened in order to carry out a diesel pilot injection via the injection opening 4 , by means of which the gaseous fuel which is subsequently injected via the injection opening 3 can be ignited.

To open the inner nozzle needle 2, the control pressure in the cylindrical control chamber 6 above the inner nozzle needle 2 is lowered by means of the control valve 8, so that the inner nozzle needle 2 can be opened as the control pressure in the control chamber 6 drops. With the control valve 8 open, the control medium present in the control chamber 6 (where the current control medium is the second medium) flows out via the outlet throttle 22 , while the medium is replenished via the input throttle 21 . However, the input quantity is smaller than the output quantity, so that the control pressure in the control chamber 6 drops and the inner nozzle needle 2 moves upwards.

To open the outer nozzle needle 1, the control pressure in the annular control chamber 5 above the outer nozzle needle 1 is lowered by means of a further control valve (not shown). As the control pressure in the control chamber 5 drops, the outer nozzle needle 1 can open.

In order to close the two nozzle needles 1, 2, the control pressure in the corresponding control chamber 5, 6 is raised again by closing the control valve.

In order to increase the pressure of the first medium, the dual-substance injector according to the invention shown in FIG. 1 has a pressurization device 10 comprising an intensifier chamber 11 arranged in the input path 9 and a delimited intensifier chamber 11 . the piston 12. Thus, the input path 9 of the first medium extends via the amplifier chamber 11 . The piston 12 is currently embodied as a stepped piston. The first section 12 . 1 is used for delimiting the intensifier chamber 11 and has a reduced diameter or a reduced transverse diameter compared to the second section 12 . 2 for delimiting the pressure chamber 13 arranged above the piston 12 . section. The piston 12 thus forms an annular shoulder 14 which delimits a further pressure chamber 15 on the side of the section 12 . 2 facing away from the pressure chamber 13 . The two pressure chambers 13 , 15 are each connected to an input path 24 for a second medium, which is currently simultaneously used as a control medium. In contrast to the first pressure chamber 13 , the connection of the further pressure chamber 15 takes place via an input throttle device 16 , so that the input is throttled. The control pressure in the further pressure chamber 15 can be varied by means of the outlet throttle 17 which can be switched on and off by means of the control valve 7 in such a way that a resultant pressure acts on the piston 12 which moves the piston 12 downwards so that the The piston sinks deeper into the intensifier chamber 11 . In this case, the piston 12 reduces the volume of the intensifier chamber 11 so that the pressure in the intensifier chamber 11 or in the supply path 9 of the first medium increases. In this way, a pressurization inside the injector is brought about in the input path 9 of the first medium. Thus, the input pressure of the first medium outside the injector can be reduced, which has the advantage of reducing the complexity of the system configuration, eg in NGDI injectors. In addition, the pressurization inside the injector has a positive effect on the thermal balance of the system.

The movement of the piston 12 is caused against the spring force of the compression spring serving as the return spring 18 . The pressure spring thus supports the return of the piston 12 when the control valve 7 is closed and the pressure in the further pressure chamber 15 rises again. Consequently, with the closing of the control valve 7 , the control medium can no longer flow out of the further pressure chamber 15 via the outlet throttle 22 , but can only flow in via the inlet throttle 21 . As a result, the piston 12 is moved upwards again, wherein it is withdrawn from the intensifier chamber 11 so that the volume of the intensifier chamber 11 increases again. In order to prevent a part of the first medium present in the input path 9 from being sucked back here, a non-return valve 20 is arranged in the input path 9 upstream of the intensifier chamber 11 .

From FIG. 2 , a development of the dual-substance injector of FIG. 1 is obtained. Since the dual-substance injector of FIG. 2 additionally has a connecting channel 19 which connects the further pressure chamber 15 of the pressure booster 10 with the annular control chamber 5 above the outer nozzle needle 1 , the control valve 7 can be used not only for The pressurization device is operated and can also be used to control the reciprocating movement of the outer nozzle needle 1 . In this way the complexity of the dual substance injector can be reduced.

Another preferred embodiment of the dual substance injector of the present invention is shown in FIG. 3 in conjunction with an injection system. A first medium (eg natural gas or hydrogen) and a second medium (eg diesel fuel) can be injected by means of the two-substance injector shown. The second medium is currently simultaneously used as a control medium, which controls the reciprocating movement of the two nozzle needles of the dual-substance injector, which are guided nested within one another.

The first medium is stored in at least one tank 25 and is supplied to the dual substance injector via the input path 9 . The input path 9 is led via an intensifier chamber 11 of the booster device 10 arranged in FIG. 3 close to the injector (not inside the injector). Depending on the type of medium and/or the type of storage, different requirements are placed on the tank 25.

中受束缚的氢气(LOHC＝“Liquid Organic Hydrogen Carrier”液态有机氢载体)。在连接在下游的脱氢单元26中，在将氢气引入到输入路径9之前，在载液中受束缚的氢气借助热量(W)被释放并且借助于低压压缩装置27被带到约10至50bar的压力水平。Tank 25 is shown in the case of I., said tank containing the carrier liquid in

bound hydrogen gas (LOHC = "Liquid Organic Hydrogen Carrier"). In the dehydrogenation unit 26 connected downstream, the hydrogen bound in the carrier liquid is released by means of heat (W) and brought to about 10 to 50 bar by means of a low-pressure compression device 27 before the hydrogen is introduced into the input path 9 stress level.

In the case of II. a cryogenic tank 25 ′ for storing cryogenic fuels, such as hydrogen or methane or liquid natural gas (LNG=“Liquefied Natural Gas”), is shown. The temperature of hydrogen is about -250°C and the temperature of methane is about -160°C. The fuel is removed from the tank 25' by means of the delivery pump 28 and brought to a delivery pressure of about 200 bar. Furthermore, the fuel is heated by means of a heat exchanger 29 connected downstream before it reaches the input path 9 .

In the case of III. a high-pressure tank 25" is shown, in which the fuel under pressure is stored. The fuel can again be hydrogen, methane or natural gas (CNG = "Compressed Natural Gas": Compressed Natural Gas). The operating pressure is between 200 and 300 bar.

The second medium (currently diesel fuel) is stored in a tank 30 and is compressed by means of a high-pressure pump 31 and supplied to a high-pressure accumulator 32 or rail. The dual substance injector is supplied with diesel fuel via a high pressure accumulator 32 . As shown in FIG. 3 , in addition to the dual-substance injector shown, other dual-substance injectors may be connected to the high-pressure accumulator 32 .

Diesel fuel supplied to the dual substance injector is used as ignition fuel and control medium. Thus, the two control chambers 5, 6 of the dual fuel can be charged with diesel fuel. The input takes place via input throttle devices 21, 33, respectively. Depending on the switching position of the control valves 7 , 8 , the unloading of the control chambers 5 , 6 is brought about by the discharge throttles 22 , 34 , respectively. In addition, diesel fuel is used to control the supercharging device 10 . For this purpose, the pressure chamber 13 arranged on the end side with respect to the piston 12 is charged with diesel fuel according to the switching position of the further control valve 35 , so that the piston 12 is charged with diesel pressure. This diesel pressure is higher than the pressure in the intensifier chamber 11 so that hydraulic pressure acts on the piston 12 , which presses the piston 12 downwards against the spring force of the return spring 18 . Here, the piston 12 sinks deeper into the intensifier chamber 11 , so that the volume of the intensifier chamber is reduced and the first medium received therein is compressed. A first non-return valve 20 arranged upstream of the booster device 10 in the input path 9 enables a pressure build-up in the intensifier chamber 11 . Subsequently, the compressed medium is supplied to the dual-material injector via a second non-return valve 36 arranged downstream of the booster device 10 in the input path 9 . In order to unload the pressure chamber 13 , a discharge throttle 17 is provided, via which the pressure chamber 13 is connected to a return flow 37 which leads back into the tank 30 .

The piston 12 of the charging device 10 of FIG. 3 is designed as a stepped piston, so that the piston 12 has a first piston section 12.1 and a second piston section 12.2. In Figure 3, the diameter of the second piston section 12.2 is chosen to be smaller than the diameter of the first piston section 12.1. A further pressure chamber 15 is delimited by a shoulder 14 formed on the piston 12 , which is likewise connected to the return 37 so that a return pressure acts in the pressure chamber 15 .

A variant of the embodiment shown in FIG. 3 is known from FIG. 4 . In this case, the control valve 35 is not designed as a 3/2-way directional valve, but as a 3/3-way directional valve. As a result, the control valve 8 for unloading the control chamber 6 above the inner nozzle needle 2 can be omitted. The control valve 35 is designed in such a way that, in the initial position, the discharge from the pressure chamber 13 via the discharge throttle 17 is open and the supply into the pressure chamber 13 is closed. The outer nozzle needle 1 is also actuated by a control valve 7 .

Another variant is shown in FIG. 5 . In this embodiment, the control valve 35 replaces the two control valves 7, 8, so that the number of valves is further reduced. However, this requires arranging the booster device 10 inside the injector, since otherwise additional pressure lines would be required.

A variant of the embodiment of FIG. 5 is shown in FIG. 6 . In this case, the piston 12 of the pressure boosting device 10 simultaneously forms a control edge 38 in the region of the shoulder 14 , which, depending on the axial position of the piston 12 , releases a relief path 39 , which passes through the outlet throttle. 34 is connected to the control room 5.

Another preferred embodiment is shown in FIG. 7 . Here, the outer nozzle needle 1 is controlled only by the applied pressure. As soon as a corresponding pressure has built up in the control chamber 5 , the nozzle needle 1 opens against the spring force of the spring 40 and/or against the hydraulic pressure. In the case of opening against the hydraulic pressure, the hydraulic and pneumatic active surfaces present on the nozzle needle 1 must be adapted to one another according to the pressure relationship.

The pressure curve and the needle stroke curve for the embodiment according to FIG. 4 are shown by way of example in FIG. 8 . The uppermost diagram shows the pressure curve in the booster device 10 , wherein the curve K1 shows the pressure p in the pressure chamber 13 over time t, and the curve K2 shows the pressure p in the booster chamber 11 over time t process.

The curve K3 in the diagram below it illustrates the input pressure of the diesel fuel, and the curve K4 the input pressure of the first medium in the input path 9 . The stroke h of the two nozzle needles 1 , 2 is shown in the diagram below, wherein the curve K5 describes the stroke h of the inner nozzle needle 2 and the curve K6 the stroke h of the outer nozzle needle 1 , which is offset in time. The curves K7 to K9 illustrate the valve travel of the control valves 7 , 8 and 35 .

The bottom graph shows the injection rate, the curve K10 indicating the diesel injection rate and the curve K11 the injection rate of the first medium or of the main fuel.

Claims (10)

1. A two-substance injector for injecting two different media, comprising two coaxially arranged nozzle needles (1,2) guided one inside the other for releasing and closing injection openings (3,4), wherein each nozzle needle (1,2) is assigned a control chamber (5,6) which can be charged with a control medium and which can be discharged as a function of the switching position of a control valve (7,8) in such a way that a control pressure acting on the nozzle needle (1,2) can be varied in order to actuate the respective nozzle needle (1,2), characterized in that a pressure boosting device (10) is arranged in the inlet path (9) of the first medium in such a way that the pressure in the inlet path (9) of the first medium can be increased.

2. The two-substance injector according to claim 1, characterized in that the pressure boosting device (10) comprises an intensifier chamber (11) arranged in the input path (9) and a piston (12) delimiting the intensifier chamber (11), such that the volume of the intensifier chamber (11) can be changed by the axial position of the piston (12).

3. The two-substance injector according to claim 2, characterized in that the piston (12) delimits, on its end facing away from the intensifier chamber (11), a pressure chamber (13) which can be charged with a pressure medium, preferably the control medium.

4. The dual substance injector according to claim 2 or 3, characterized in that the piston (12) is embodied as a stepped piston.

5. The two-substance injector according to claim 4, characterized in that the piston (12) has a first section (12.1) which delimits the intensifier chamber (11) and a second section (12.2) which delimits the pressure chamber (13) and has an increased diameter compared to the first section (12.1) such that an annular shoulder (14) is formed which delimits a further pressure chamber (15).

6. Dual substance injector according to claim 5, characterized in that the further pressure chamber (15) can be charged with the control medium by an input throttle (16) and can be discharged by an outlet throttle (17) depending on the switching state of the control valve (7).

7. The dual substance injector according to one of claims 2 to 6, characterized in that the piston (12) is substantially pressure-balanced with the control valve (7) closed.

8. The dual substance injector according to one of claims 2 to 7, characterized in that the piston (12) is supported on a return spring (18), which is preferably configured as a pressure spring and is received in the further pressure chamber (15).

9. The two-substance injector according to one of claims 5 to 8, characterized in that the further pressure chamber (15) is connected to the control chamber (5) by a connecting channel (19) for controlling the reciprocating movement of the first nozzle needle (1).

10. Two-substance injector according to one of the preceding claims, characterized in that in the inlet path (9) of the first medium, upstream of the pressure boosting device (10), a non-return valve (20) is arranged, which is shut off against the inlet direction.

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