METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE SYSTEM USING HYDROGEN FUEL

Abstract

A method for operating an internal combustion engine system using gaseous fuel is disclosed. The method includes injecting, by activating a fuel injector to generate a first injection in association with a compression stroke, a first amount of gaseous fuel into a pre-combustion chamber, wherein the first injection and the first amount of gaseous fuel are adapted so that an ignitable fuel-air mix is formed in the pre-combustion chamber but not in a main combustion chamber; igniting, by activating an igniter, the ignitable fuel-air mix in the pre-combustion chamber formed by the first injection; and injecting, by activating the fuel injector to generate a second injection after ignition of the first amount of fuel, a second amount of gaseous fuel into the pre-combustion chamber, wherein the second injection and the second amount of gaseous fuel are adapted so that fuel is forced through the orifices into the main combustion chamber.

Claims

1. A method for operating an internal combustion engine system using gaseous fuel, wherein the internal combustion engine system comprises: a piston arranged to reciprocate in a cylinder between a bottom dead center (BDC) and a top dead center (TDC), wherein a position of the piston during a compression stroke when the piston moves towards the TDC can be represented by ?180? crank angle degrees (CAD) at the BDC and 0? CAD at the TDC; a main combustion chamber arranged at an end portion of the cylinder so that an upper surface of the piston defines a lower side of the main combustion chamber; an inlet valve and an exhaust valve arranged to regulate flow of air and exhaust gas to and from the main combustion chamber; a pre-combustion chamber arranged in association with the main combustion chamber, wherein the pre-combustion chamber is provided with one or more orifices allowing fluid communication between the pre-combustion chamber and the main combustion chamber; a fuel injector arranged to inject gaseous fuel into the pre-combustion chamber; and an igniter arranged to ignite a fuel-air mix present in the pre-combustion chamber, the method comprising: injecting, by activating the fuel injector to generate a first injection in association with a compression stroke, a first amount of gaseous fuel into the pre-combustion chamber, wherein the first injection and the first amount of gaseous fuel are adapted so that an ignitable fuel-air mix is formed in the pre-combustion chamber but not in the main combustion chamber, igniting, by activating the igniter, the ignitable fuel-air mix in the pre-combustion chamber formed by the first injection, injecting, by activating the fuel injector to generate a second injection after ignition of the first amount of fuel, a second amount of gaseous fuel into the pre-combustion chamber, wherein the second injection and the second amount of gaseous fuel (3A) are adapted so that fuel is forced through the orifices into the main combustion chamber.

2. The method of claim 1, wherein the second amount of fuel is larger than the first amount of fuel.

3. The method of claim 2, wherein the second amount of fuel is at least 50% larger, or at least 100% larger, or at least 500% larger, than the first amount of fuel.

4. The method of claim 1, wherein a duration of the first injection is less than 5? CAD.

5. The method of claim 4, wherein the duration of the first injection is 0.5-2? CAD.

6. The method of claim 1, wherein a duration of the second injection (3) is >0.5? CAD, or >1? CAD.

7. The method of claim 6, wherein the duration of the second injection is <20? CAD, or <15? CAD.

8. The method of claim 1, wherein the first injection is initiated somewhere between ?160? and ?10? CAD.

9. The method of claim 1, wherein the first injection is initiated somewhere between ?160? and ?45? CAD.

10. The method of claim 9, wherein the first injection is initiated after ?110? CAD.

11. The method of claim 9, wherein the first injection is initiated before ?10? CAD, or before ?45? CAD.

12. The method of claim 1, wherein the ignition is initiated somewhere between ?45? and +10? CAD, or between ?20? and ?10? CAD.

13. The method of claim 1, wherein the second injection is initiated somewhere between ?10? and +10? CAD.

14. The method of claim 13, wherein the second injection is initiated at or after ?5? CAD.

15. The method of claim 13, wherein the first injection is initiated at or before 0? CAD.

16. The method of claim 1, wherein the gaseous fuel is hydrogen gas.

17. An internal combustion engine system comprising: a piston arranged to reciprocate in a cylinder between a bottom dead center (BDC) and a top dead center (TDC), wherein a position of the piston during a compression stroke when the piston moves towards the TDC can be represented by ?180? crank angel degrees (CAD) at the BDC and 0? CAD at the TDC; a main combustion chamber arranged at an end portion of the cylinder so that an upper surface of the piston defines a lower side of the main combustion chamber; an inlet valve and an exhaust valve arranged to regulate flow of air and exhaust gas to and from the main combustion chamber; a pre-combustion chamber arranged in association with the main combustion chamber, wherein the pre-combustion chamber is provided with one or more orifices allowing fluid communication between the pre-combustion chamber and the main combustion chamber; a fuel injector arranged to inject gaseous fuel into the pre-combustion chamber; and an igniter arranged to ignite a fuel-air mix present in the pre-combustion chamber, and a control circuitry configured to: inject, by activating the fuel injector to generate a first injection in association with a compression stroke, a first amount of gaseous fuel into the pre-combustion chamber, wherein the first injection and the first amount of gaseous fuel are adapted so that an ignitable fuel-air mix is formed in the pre-combustion chamber but not in the main combustion chamber, ignite, by activating the igniter, the ignitable fuel-air mix in the pre-combustion chamber formed by the first injection, and inject, by activating the fuel injector to generate a second injection after ignition of the first amount of fuel, a second amount of gaseous fuel into the pre-combustion chamber, wherein the second injection and the second amount of gaseous fuel are adapted so that fuel is forced through the orifices into the main combustion chamber.

18. A vehicle provided with an internal combustion engine system according to claim 17.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Examples are described in more detail below with reference to the appended drawings.

[0052] FIG. 1 is an exemplary view of timing of fuel injection and ignition according to this disclosure.

[0053] FIGS. 2-4 show schematically the combustion process according to this disclosure.

DETAILED DESCRIPTION

[0054] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0055] FIG. 1 illustrates an example of timing for a first fuel (hydrogen) injection 1, an ignition 2 and a second fuel (hydrogen) injection 3 for an internal combustion engine operating according to a four-stroke cycle with an intake stroke starting at ?360? (crank angel degrees, CAD), a compression stroke starting at ?180?, an expansion stroke starting at 0?, and an exhaust stroke starting at 180?.

[0056] As shown in FIG. 1, the first injection 1 has a relatively short duration and is in this example carried out at around ?110? CAD. The ignition 2 is carried out at around ?20? CAD and the second injection is initiated at around ?10? CAD. The second injection 2 involves injection of a second amount of fuel that may be 10 times larger than a first amount of fuel injected in the first injection 1. A duration of the second fuel injection is around 30? CAD.

[0057] FIGS. 2-4 show a part of an internal combustion engine system 20 comprising a piston 4 arranged to reciprocate in a cylinder 5 between a bottom dead center (BDC, not shown) and a top dead center (TDC, roughly as positioned in FIG. 3). With reference to FIG. 1, the piston is in the TDC position at ?360?, 0? and 360? CAD. The piston 4 is via a connection rod (not shown) connected to a crank shaft (not shown) in line with a conventional internal combustion engine.

[0058] FIGS. 2-4 further show a main combustion chamber 6 arranged at an end portion of the cylinder 5 so that an upper surface 7 of the piston 4 defines a lower side of the main combustion chamber 6. An inlet valve 8 and an exhaust valve 9 are arranged to regulate flow of air and exhaust gas to and from the main combustion chamber 6 via corresponding ducts 10, 11.

[0059] A pre-combustion chamber 12 is arranged in association with the main combustion chamber 6. In this case the pre-combustion chamber 12 is located partly outside of the main combustions chamber 6. The pre-combustion chamber 12, or rather a wall defining the pre-combustion chamber 12, is provided with a plurality of orifices 13 allowing fluid communication between the pre-combustion chamber 12 and the main combustion chamber 6.

[0060] A fuel injector 14 is arranged to inject hydrogen fuel into the pre-combustion chamber 12. The injector 14 is arranged so that a fuel outlet thereof is enclosed by the pre-combustion chamber 12.

[0061] An igniter 15, such as a spark plug or similar, is arranged to ignite a fuel-air mix present in the pre-combustion chamber.

[0062] FIG. 2 shows the situation when the first injection 1 just has been performed by the injector 14 so that the first amount of fuel 1A just has been injected into the pre-combustion chamber 12. The piston 4 is here positioned at, for instance, ?100? CAD and is moving towards the TDC in the compression stroke. Air in the main combustion chamber 6 is compressed and forced through the orifices 13 into the pre-combustion chamber 12 and mixes therein with the first amount of fuel 1A.

[0063] FIG. 3 shows the situation when the igniter 15 just has been activated so as to ignite the fuel-air mix in the pre-combustion chamber 12. Temperature and pressure increases rapidly in the pre-combustion chamber 12 and burning fuel-mix is forced through the orifices 13 into the main combustion chamber 6 (indicated by small jets 16). The piston 4 is here close to TDC.

[0064] FIG. 4 shows the situation when the second injection 3 just has been performed by the injector 14 so that the second (larger) amount of fuel 3A just has been injected into the pre-combustion chamber 12. Because the second amount of fuel 3A is sufficiently large and has a sufficiently high pressure, it is forced further through the orifices 13 into the main combustion chamber 6 (indicated by large jets 17). Some portion of the second amount of fuel 3A may start burning (i.e., reacting with oxygen in the air) inside the pre-combustion chamber 12 but a large portion will push burning fuel in front of itself into the main combustion chamber 6 and start burning only after having entered the main combustion chamber 6. In FIG. 4, the piston 4 has passed the TDC and has started moving towards the BDC.

[0065] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms a, an, and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms comprises, comprising, includes, and/or including when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and/or groups thereof.

[0066] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0067] Relative terms such as below or above or upper or lower or horizontal or vertical may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being connected or coupled to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being directly connected or directly coupled to another element, there are no intervening elements present.

[0068] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0069] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.