INJECTOR AND ARRANGEMENT WITH ONE INJECTOR

Description

Technical field

[0001] The invention relates to an injector for delivering a pressurized working medium into a combustion chamber of an internal combustion engine. In particular, the invention relates to an injector for injecting alternative fuels such as ammonia or alcohols such as ethanol or methanol, wherein the stroke movement of a nozzle needle is effected by a control medium different from the working medium. State of the art

[0002] An injector is known from DE 10 2017 217 991 A1 of the applicant. The known injector is characterized by two pressure chambers, each fillable with a different medium, in which a nozzle needle is arranged to move freely. The two pressure chambers are separated from each other by a bellows extending transversely to the longitudinal direction of the nozzle needle, creating a media-tight seal. The pressure chamber located opposite the inlet openings of the injector can be filled with a control medium to influence the longitudinal movement of the nozzle needle, while the pressure chamber facing the inlet openings can be filled with the working medium that can be discharged from the injector via the inlet openings. Crucially, in a state where the two pressure chambers are not filled with pressurized media, no force acting in the closing direction of the nozzle needle, and thus closing the inlet openings, is generated on the nozzle needle.

[0003] Another injector of this type is known from DE 10 2018 211 510 A1 of the applicant. In this injector as well, when the control chamber is not subjected to the (hydraulic) pressure of a control medium, no force is exerted on the nozzle needle in the direction of its position closing the inlet openings.

[0004] From US6749129B2 an injector with the characteristics of the general term of claim 1 is known. Disclosure of the invention

[0005] The injector according to the invention for dispensing a pressurized working medium into a combustion chamber of an internal combustion engine with the features of claim 1 has the advantage that it seals the pressure chamber, which is filled with the working medium, against the combustion chamber in a state in which the control chamber is not hydraulically acted upon by the pressure of the control medium, by acting the nozzle needle into its closed position.

[0006] In particular, the injector according to the invention enables the generation of a relatively high closing force acting on the nozzle needle in the direction of the closing position. This is particularly advantageous when the injector is used together with another injector for dispensing or injecting working fluid into a combustion chamber, wherein the injector according to the invention injects, for example, ammonia or alcohols such as ethanol or methanol into the combustion chamber, and the other injector is designed, in particular, for injecting diesel fuel. It is essential that, in an operating condition in which the other injector is injecting the (diesel) fuel into the combustion chamber while the injector according to the invention is depressurized or deactivated, the combustion chamber pressure generated by the operation of the other injector does not allow combustion chamber gases to penetrate the injector according to the invention, which could potentially damage the injector.

[0007] In other words, this means that the closing force that can be generated on the nozzle needle by at least one closing spring in the injector according to the invention is designed such that it is at least as large as the combustion chamber pressure when the internal combustion engine is operated with a different injector in order to keep the nozzle needle in its closed position.

[0008] In light of the above explanations, an injector according to the invention is therefore provided that the nozzle needle is coupled to at least one closing spring, in particular arranged in contact with the at least one closing spring, wherein the at least one closing spring exerts a spring force on the nozzle needle in the direction of its closed position. Furthermore, the nozzle needle has a section in the control chamber which is radially surrounded by a guide sleeve, and the guide sleeve is subjected to a force by a first closing spring against a component that delimits the control chamber. Such a design makes it particularly possible to arrange a second closing spring, provided for generating a relatively high closing force on the nozzle needle, outside the control chamber in a separate spring chamber, wherein the control chamber is sealed off from this other chamber (spring chamber) by the guide sleeve.A second closing spring is arranged in a spring chamber separate from the low-pressure area. This second closing spring is designed to exert a greater force on the nozzle needle towards its closed position than the first closing spring. In particular, this design allows the second closing spring to have virtually any size, shape, and geometry without negatively affecting or increasing the size of the control chamber.

[0009] Advantageous further developments of the injector according to the invention for dispensing a pressurized working medium into a combustion chamber of an internal combustion engine are listed in the dependent claims.

[0010] With regard to typical combustion chamber pressures when using an (additional or second) injector designed to inject liquid fuel or (diesel) fuel into the combustion chamber, it is provided that the nozzle needle, viewed in the direction of its longitudinal axis, is guided radially in a guide section of the injector housing between the pressure chamber for the working medium and the control chamber for the control medium; that the pressure of the control medium in the control chamber acts on a control surface arranged perpendicular to the longitudinal axis of the nozzle needle; that the nozzle needle, in its closed position, rests against a wall section of the pressure chamber, forming a sealing seat; and that the area of ​​the nozzle needle in the area of ​​the sealing seat corresponds to a maximum of 41% of the area in the area of ​​the guide section, and the area of ​​the control surface corresponds to between 23% and 74% of the area in the area of ​​the guide section.

[0011] To generate a force acting in the opening direction of the nozzle needle to release the inlet openings during a pressure reduction in the control chamber, it is provided that the nozzle needle in the pressure chamber for the working medium has a pressure surface which is designed to generate a force acting in the opening direction on the nozzle needle under the hydraulic pressure of the working medium.

[0012] In a preferred further development, it is provided that the component to which the guide sleeve (sealing) rests is a throttle plate.

[0013] To provide an additional seal between the control medium in the control chamber and the working medium in the pressure chamber, a radial groove extending around the longitudinal axis of the nozzle needle can be formed in the guide section. This groove can be filled with a barrier medium. This barrier medium can, for example, be a barrier oil with a relatively high viscosity, thus hindering mixing of the barrier medium with the working medium or the control medium.

[0014] The invention further comprises an arrangement for supplying working medium to the combustion chamber of an internal combustion engine with a first injector as described above, and with a second injector which is designed to inject a working medium different from that of the first injector into the combustion chamber, wherein the combustion chamber pressure when operating the internal combustion engine with the second injector is at most about 350 bar.

[0015] It is particularly preferred that the arrangement is designed to supply an alternative fuel such as ammonia or alcohols such as ethanol or methanol as a working medium for the first injector and diesel fuel for the second injector into the combustion chamber of the internal combustion engine.

[0016] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Brief description of the drawings

[0017] Fig. 1 shows a schematic representation of an arrangement of two injectors in the area of ​​a combustion chamber of an internal combustion engine and Fig. 2 shows an injector for delivering a working medium, in particular liquid, into the combustion chamber of the internal combustion engine in a simplified longitudinal section. Embodiments of the invention

[0018] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0019] In the Fig. 1 An arrangement 100 is shown in which two injectors 10, 20 are provided in the region of a combustion chamber 1 of an internal combustion engine 2 in order to deliver, inject, or blow different working media into the combustion chamber 1 of the internal combustion engine 2. In particular, the first injector 10 is configured to inject a first working medium, in particular an alternative fuel such as ammonia or alcohols such as ethanol or methanol, stored in a reservoir 12 into the combustion chamber 1, while the other injector 20 is configured to inject a second working medium, in particular diesel fuel, stored in a second reservoir 14 into the combustion chamber 1.

[0020] Furthermore, it is essential that the two injectors 10 and 20 can be operated together, particularly when the other injector 20 serves as the ignition source for igniting the working fluid of the first injector 10. However, the first injector 10 can also be deactivated if necessary, for example, if no first working fluid is available. In this case, the internal combustion engine 2 is operated exclusively with the other, second injector 20.

[0021] The one in Fig. 2 The injector 10, shown in more detail, has an injector housing 22 in which a recess 24 is formed, the recess having several sections with different diameters. The injector housing 22 has several inlet openings 26 on the side facing the combustion chamber 1, which are designed to inject the (gaseous) working medium into the combustion chamber 1 of the internal combustion engine 2. For this purpose, the recess 24 on the side facing the inlet openings 26 forms a pressure chamber 28, which can be connected to the pressurized working medium via a feed bore 30.

[0022] Within the recess 24, a nozzle needle 34 is arranged to move freely in the direction of a longitudinal axis 32. In the Fig. 2 In the closed position shown, a conical nozzle needle end 35 sits against the recess 24 in the area of ​​a wall section 36 of the recess 24, forming a sealing seat 38 to at least indirectly close the inlet openings 26. The nozzle needle 34 also has sections with different diameters within the pressure chamber 28, such that a pressure surface 39, which in the exemplary embodiment is conical, generates an opening force on the nozzle needle 34 when the pressure chamber 28 is hydraulically pressurized by the working medium, releasing the inlet openings 26.

[0023] The nozzle needle 34 is guided radially in a guide section 40 of the recess 24 in a central region, viewed longitudinally. In the region of the guide section 40, the nozzle needle 34, or the guide section 40, has a constant diameter D. Also approximately in a central region of the guide section 40, a radially circumferential annular groove 42 is formed in the wall of the recess 24, extending around the longitudinal axis 32. This groove can be filled with a barrier medium, such as a barrier oil, via a supply channel 44. If the injector 20 is designed as a diesel injector, the barrier medium or barrier oil can be taken from the fuel circuit of the injector 20; that is, the barrier medium can then be diesel fuel.

[0024] The nozzle needle 34 projects into a control chamber 46 on the side facing away from the inlet openings 26 with a section 45 reduced in diameter. This control chamber is also formed in the recess 24. The control chamber 46 is connected via an inlet bore 48 to a reservoir 49 for a pressurized control medium, the control medium being different from the working medium. Furthermore, the control chamber 46 can be pressure-relieved into a low-pressure area 52 via a drain bore 50. A valve 54 serves this purpose, allowing the control medium to drain from the control chamber 46 when open. The valve 54 can be actuated, for example, by means of a magnetic actuator, as is known from the prior art and therefore not described in detail here.

[0025] The control chamber 46, or the recess 24, is closed on the side opposite the inlet openings 26 by a throttle plate 55, in which an inlet throttle 56 for the inlet channel 44 and an outlet throttle 57 for the outlet bore 50 are formed. Furthermore, the throttle plate 55 has a through bore 58 concentric to the longitudinal axis 32, which opens into a spring chamber 60 on the side opposite the control chamber 46.

[0026] Within the control chamber 46, the section 45 of the nozzle needle 34, which acts as a guide section, is radially surrounded by a guide sleeve 62. This sleeve serves to seal the through-bore 58 in the direction of the spring chamber 60. For this purpose, the guide sleeve 62, which has a conically shaped sealing edge 63 on the side facing the throttle plate 55 and extending radially around the longitudinal axis 32, is subjected to the spring force of a first closing spring 64 in the direction of the throttle plate 55. The first closing spring 64 is supported on the nozzle needle 34 in the area of ​​an annular control surface 65 that extends radially around the longitudinal axis 32.

[0027] The nozzle needle 34 passes through the through-bore 58 with a section 66 whose diameter is further reduced and which, in the area of ​​the spring chamber 60, is enlarged in diameter in a disc-like manner. A second closing spring 68 is arranged in the spring chamber 60, which is characterized by the fact that it is supported against a housing-fixed component of the injector 10 (not shown) and exerts a greater spring force on the nozzle needle 34 in the direction of the sealing seat 38 than the spring force of the first closing spring 64.

[0028] To deliver working fluid into the combustion chamber 1 of the internal combustion engine 2 via the injector 10, the pressure chamber 28 is filled with working fluid (gas) under high pressure. To lift the nozzle needle 34 from its position in the Fig. 2To change the closed position shown from an open position, in which the working medium can flow out into the combustion chamber 1 via the inlet openings 26, it is necessary to reduce the pressure in the control chamber 46. This is achieved by actuating the valve 54, allowing the control medium to flow into the low-pressure chamber 52. The opening force required to open the nozzle needle 34 is generated by the working medium acting against the pressure surface 39 on the nozzle needle 34 in the pressure chamber 28.

[0029] To close the nozzle needle 34, the hydraulic pressure in the control chamber 46 is increased by closing the valve 54, which causes a hydraulic (additional) closing force in the direction of the closing position of the nozzle needle 34, whereby the spring forces of the two closing springs 64 and 68, together with the hydraulic closing force through the control medium in the control chamber 46, must be greater than the force acting on the nozzle needle 34 in the opening direction through the working medium located in the pressure chamber 28 at the pressure surface 39.

[0030] Furthermore, it is essential that when injector 10 is not in operation, particularly when the internal combustion engine 2 is operated with liquid (gasoline) fuel or working fluid via the second injector 20, the nozzle needle 34 remains in its closed position against the combustion chamber pressure prevailing in the combustion chamber 1, which can typically reach up to approximately 350 bar. This is made possible by the spring force of the two closing springs 64, 68. With regard to the aforementioned maximum combustion chamber pressure, it has been found to be necessary that the area AS of the nozzle needle 34 in the region of the sealing seat 38 corresponds to a maximum of 41% of the area AF in the region of the guide diameter of the nozzle needle 34 or the guide section 40, and that the area A St of the section 66 at the level of the control surface 65 corresponds to between 23% and 74% of the area AF in the region of the guide diameter of the nozzle needle 34 or the guide section 40.

[0031] The injector 10 described so far can be modified or adapted in a variety of ways without deviating from the inventive concept.

Claims

1. Injector (10) for dispensing a pressurized working medium into a combustion chamber (1) of an internal combustion engine (2), with an injector housing (22), in which a nozzle needle (34) is arranged longitudinally displaceably between a closed position which closes at least one inlet opening (26) for the working medium into the combustion chamber (1) and an open position which releases the at least one inlet opening (26), with a pressure chamber (28) arranged in the injector housing (22) for the working medium, and with a control chamber (46) which is arranged in the injector housing (22) and can be filled with a pressurized control medium, different from the working medium, wherein the pressure of the control medium applies force to the nozzle needle (34) in the direction of its closed position, wherein the control chamber (34) is pressure-relievable via a control valve (54) into a low-pressure region (52), and wherein the pressure chamber (28) and the control chamber (46) are hydraulically separated from each other, and the nozzle needle (34) is coupled to at least one closing spring (64, 68), in particular is arranged in bearing contact with the at least one closing spring (64, 68), wherein the at least one closing spring (64, 68) subjects the nozzle needle (34) to spring force in the direction of its closed position, characterized in that the nozzle needle (34) has, in the control chamber (46), a portion (45) which is radially surrounded by a guide sleeve (62), and in that the guide sleeve (62) has force applied to it by a first closing spring (64) against a component delimiting the control chamber (46), wherein a second closing spring (68) is arranged in a spring chamber (60) separate from the low-pressure region (52), and the second closing spring (68) is designed to apply a greater force to the nozzle needle (34) in the direction of its closed position than the first closing spring (64).

2. Injector according to Claim 1, characterized in that the nozzle needle (34) is radially guided in a guide portion (40) of the injector housing (22), as viewed in the direction of its longitudinal axis (32), between the pressure chamber (28) for the working medium and the control chamber (46) for the control medium, in that the pressure of the control medium in the control chamber (46) acts on a control surface (65) which is arranged perpendicularly with respect to the longitudinal axis (32) of the nozzle needle (34), in that, in its closed position, the nozzle needle (34) bears, with the formation of a sealing seat (38), against a wall portion (36) of the pressure chamber (28), and in that the surface area (AS) of the nozzle needle (34) in the region of the sealing seat (38) corresponds to a maximum of 41 % of the surface area (AF) in the region of the guide portion (40), and the surface area (ASt) of the control surface (65) corresponds to between 23% and 74% of the surface area (AF) in the region of the guide portion (40).

3. Injector according to Claim 1 or 2, characterized in that the nozzle needle (34) has a pressure surface (39) for the working medium in the pressure chamber (28), which pressure surface is designed to generate a force, acting into the opening position which releases at least one inlet opening (26), on the nozzle needle (34) under the hydraulic pressure of the working medium.

4. Injector according to Claim 1, characterized in that the component is designed as a throttle plate (55).

5. Injector according to one of Claims 1 to 4, characterized in that a groove (42) which runs radially around the longitudinal axis (32) and can be filled with a sealing medium is formed in the region of the guide portion (40).

6. Arrangement (100) for dispensing working medium into the combustion chamber (1) of an internal combustion engine (2), comprising a first injector (10) which is designed according to any one of Claims 1 to 5, and a second injector (20) which is designed to inject a working medium different from the first injector (10) into the combustion chamber (1), wherein the combustion chamber pressure when operating the internal combustion engine (2) with the second injector (20) is up to approximately 350 bar.

7. Arrangement according to Claim 6, characterized in that the first injector (10) is designed to dispense an alternative fuel such as ammonia or else alcohols such as ethanol or methanol as the working medium, and the second injector (20) is designed to dispense diesel fuel as the working medium, into the combustion chamber (1).a