THROTTLE ELEMENT AND GAS ENGINE WITH THROTTLE ELEMENT

Technical Field

The present invention pertains to a throttle element for an intake duct of a gas engine, comprising a housing having a flow channel and a flap mounted therein. The present invention also pertains to a gas engine comprising a mixing device in an air intake duct and a throttle element provided upstream of the gas mixing device. The throttle element comprises a housing having a flow channel and a flap mounted therein. Technological Background

As a function of its shaft rotation, a gas engine sucks in ambient air through dedicated air intake ducts. Passing through an air intake duct, the sucked in air usually passes a nozzle, thereby sucking combustion gases from a combustion gas feed duct into the air flow taking advantage of the Venturi effect. The combustion gases used can vary greatly by their ignitability, caloric value and chemical composition. Some of those gases, such as landfill gases, biogases, mine gases or gases from chemical processes can have a low intrinsic caloric value. In addition, those gases may also have a low outlet pressure as a feedstock gas sourced from their well. Further, the gas composition can also fluctuate during operation and within a system. Utilizing such gases as combustion gas in a gas engine requires a very precisely set fuel gases / air ratio to start and operate the gas engine.

Operating the gas engine at a low shaft rotation, for example during starting the engine, the air velocity within the Venturi nozzle may be too small to create a sufficient combustion gas / air ratio which leads to gas engine startup errors, irregular ignitions and/or misfiring incidents. To avoid such gas engine startup difficulties, it is suggested to reduce the effective flow cross-section for the air traveling through the air intake duct, thereby increasing velocity and ultimately the Venturi effect. Thereby, combustion gas admixing may be increased. However, reducing the flow cross- section beyond a given extent may lead to an improper combustion gas / air ratio for example by increasing the combustion gas content beyond its ignition limit.

While adjusting the flow cross-section continuously to the current gas engine operation can provide an ideal combustion gas / air ratio even for low caloric combustion gases and during gas engine startup, the latter requires detailed characteristic diagrams taking into account the specific gas engine, the combustion gas composition and various thermodynamic boundary conditions.

The throttle element of the present disclosure solves one or more problems set forth above.

Summary of the Invention Starting from the prior art, it is an objective to provide a simple, cost-effective and reliable throttle element for an intake duct of a gas engine, allowing to create a fuel composition of low calorific combustion gas and air sufficient for gas engine startup at low shaft rotations.

This objective is solved by means a throttle element with the features of claim 1 and a gas engine according to claim 8. Preferred embodiments are set forth in the present specification, the Figures as well as the dependent claims.

Accordingly, a throttle element for an intake duct of a gas engine is provided. The throttle element comprises a housing having a flow channel and a flap mounted therein. The flap is configured such that a flow cross-section of the flow channel is self-adjusting as a function of a flow through the flow channel.

Furthermore, a gas engine is provided, comprising a gas mixing device in an air intake duct and a throttle element provided upstream of the gas mixing device, wherein the throttle element comprises a housing having a flow channel and a flap mounted therein. The flap is configured such that a cross section of the flap the self-adjusting as a function of the flow through the flow channel. Brief Description of the Drawings

The present disclosure will be more readily appreciated by reference to the following detailed description when being considered in connection with the accompanying drawings in which:

Fig. 1 A schematically shows an embodiment of a throttle element for an intake duct of a gas engine in a first position and in three different views;

Fig. IB schematically shows the throttle element of Fig. 1 A and a second position and in three different views;

Fig. 2A schematically shows an embodiment of a throttle element for an intake duct of a gas engine in a first position; Fig. 2B schematically shows the throttle element of Fig. 2A and a second position;

Fig. 3 shows a gas engine according to an embodiment;

Fig. 4 shows a gas engine according to another embodiment; and

Fig. 5 shows a gas engine according to a further embodiment. Detailed Description of Preferred Embodiments

In the following, the invention will be explained in more detail with reference to the accompanying figures. In the Figures, like elements are denoted by identical reference numerals and repeated description thereof may be omitted in order to avoid redundancies. The present disclosure is generally directed to a throttle element for an intake duct of a gas engine and a gas engine comprising such a throttle element. According to embodiments of the present disclosure, the throttle element provides a simple, cost-effective and reliable throttle element which is usually installed in an air intake duct of a gas engine.

The throttle element of the present disclosure represents a component of a gas supply device of a stationary gas engine and may be configured to be used in combination with a Venturi nozzle or another gas mixing device which is configured to provide combustion gas as a function of an air flow passing through the gas mixing device. In principle, the throttle element of the present disclosure is a passive, or self-adjusting, device, actuated predominantly by the total pressure of a gas flow through the throttle element acting on a flap thereof. To this end, the throttle element of the present disclosure is relatively simple, modular and allows establishing a negative pressure for a wide range of flows through the intake duct of the gas engine with relatively minimal efforts for marginal costs.

Thereto, the present invention and its underlying principles are explained exemplary for throttle element for an air intake duct of a gas engine.

Figure 1 A schematically illustrates an embodiment of a throttle element 100 for an air intake duct of a gas engine in a first actuation position. Likewise, Figure IB schematically illustrates the throttle element 100 of Figure 1 A in another actuation position. Figures 1 A and IB each illustrate the throttle element 100 from three different perspectives as follows. The upper illustration of each of Figures 1 A and IB shows the throttle element 100 in a simplified perspective view. In these upper illustrations, section planes I-II and III-IV are indicated, wherein the middle illustrations of Figures 1 A and IB each represent their upper illustration along the sectional plane I-II and their lower illustrations of Figures 1 A and IB represent their upper illustrations along the sectional plane

III-IV respectively.

In Figures 1 A and IB, the throttle element 100 comprises a housing 10 having a flow channel 12 and a flap 14 mounted therein. The flap 14 is configured such a flow cross-section A of the flow channel 12 is self-adjusting as a function of the flow F through the flow channel 12. As an example, the flap 14 may be configured such that it is held in a closed position by gravitational forces. Acting on the flap 14, the momentum of the flow F inside the flow channel may then push the flapl4 open and establish a flow cross-section A in the flow channel 12.

In Figure 1 A, the flap 14 may be self-adjusted to a large flow F through the flow channel 12. As shown in the sectional plane I-II of figure 1 A, the flow cross-section A (crosshatched area) may be large respectively. As shown in the sectional plane III-IV of Figure 1 A, the flow cross-section A of the flow channel 12 may depend on the opening angle a which is large correspondingly. According to this scenario, the flow F through the flow channel 12 is altered to a very limited extent. This scenario may represent a nominal operation of a gas engine (not shown). During such an operation, the flap 14 and the throttle element 100 altogether may not be needed. Likewise, in Figure IB, the flap 14 may be self-adjusted to a small flow F through the flow channel 12. As shown in the sectional plane I-II of figure IB, the flow cross-section A (crosshatched area) may be small respectively. As shown in the sectional plane III-IV of Figure IB, the flow cross-section A of the flow channel 12 may depend on the opening angle a which is small correspondingly.

This scenario may be present during a startup operation of a gas engine (not shown). During such an operation, the gas engine may for example have shaft rotation of about 100-150 Rpm. In such a scenario, the flap 14 of the throttle element 100 may be needed. By self-adjusting such that the flow cross- section A of the flow channel 12 may be small. Since the overall flow cross- section may now be restricted, a lower pressure downstream of the flow F after the flap 14 may be established, which may cause higher flow velocities and thus an increased Venturi effect. The flap 14 of the throttle element 100 may be configured to be pivotable about an axis of rotation Z running transversely to a direction of the flow F through the flow channel 12. To this end, the opening angle a may revolve about the axis of rotation Z running transversely to a direction of the flow F through the flow channel 12 and is measured from the sectional plane I-II to the flap 14. Accordingly, the flow cross-section A of the flow channel 12 may represent the area resulting from the circular cross-section of the flow channel 12 minus the ellipse representing the flap 14 which is opened by the opening angle a as shown in the middle illustrations of figures 1A and IB. In view thereof, the flap 14 may be configured such that the flow cross-section A increases with increasing flow through the flow channel 12 decreases with decreasing flow through the flow channel 12. In a state when no flow F is flowing through the flow channel 12, the flow cross-section A may be very small or almost zero. For a = 0°, the flow cross-section A of the flow channel 12 may be zero, representing a scenario, wherein the flow F flowing through the flow channel 12 may be very small or almost 0.

For a = 90°, the flow cross-section A of the flow channel 12 may be almost the same cross-section of the flow channel 12 without the presence of the flap 14, representing a scenario, wherein the flow F flowing through the flow channel 12 is large.

The throttle element 100 may comprise a damping element 18, configured to dampen the movement of the flap 14 such that natural oscillation of the flap 14 is avoided, wherein the damping element 18 may comprise an electric, hydraulic and/or mechanical component. The damping element 18 may be adjusted. The flap 14 may be designed such that it is self-adjusting as a function of a flow F through the flow channel 12, wherein the flow F may consist only of air.

Figure 2A schematically illustrates another embodiment of a throttle element 100 for an air intake duct of a gas engine in a first actuation position. Likewise, Figure IB schematically illustrates the throttle element 100 of Figure 2A in another actuation position.

The embodiment shown in Figures 2A and 2B differ from the embodiment shown in Figures 1 A and IB only in that the throttle element 100 may comprise an actuator 20 configured to actuate the flap 14, wherein the actuator 20 may comprise electrical and/or mechanical actuation means. The actuator 20 is configured such that the flap 14 is still self-adjusting as a function of a flow F through the flow channel 12. For example, the actuator 20 may be configured such that it supports, secures and/or enhances a movement of the flap 14. In particular, the actuator 20 may be configured such that it compensates friction losses of the flap 14. To this end, the actuator may comprise sensor means (not depicted in Figures 2A and 2B), configured to sense a movement of the flap and/or a flow F through the flow channel 12 of the throttle element 100.

In all other aspects, the embodiment shown in Figures 2A and 2B may be identical to the embodiment shown in Figures 1A and IB.

Figure 3 shows a gas engine 200 according to a first embodiment. The gas engine 200 comprises a gas mixing device 210 which may include a combustion gas feed duct 215 configured to feeding combustion gas into the gas mixing device 210. The gas engine 200 further comprises a throttle element 100 provided upstream of the gas mixing device 210, wherein the throttle element 100 comprises a housing 10 having a flow channel 12 and a flap 14 mounted therein. The flap 14 is configured such that a cross-section A of the flap 14 is self- adjusting as a function of a flow F through the flow channel 12.

According to the embodiment shown in Figure 3, the throttle element 100 may represent a throttle element 100 according to the embodiments shown in Figures 1 A and 2 A or 2 A and 2B. More specifically, the shown throttle element 100 Figure 3 may represent the throttle element 100 as shown in figure IB, representing a situation in which the flow F through the flow channel 12 and hence through the air intake duct 220 is small. The gas mixing device 210 of the gas engine 200 may be of the Venturi type and may be configured to admix at least one combustion gas with the flow F through the flow channel 12.

Throttled by the restricted flow cross-section A due to the self- adjusted flap 14, the flow F is accelerated downstream of the flap 14 which is indicated by the arrow representing the Venturi flow Fv in Figure 3. Thereby, a negative pressure in the combustion gas feed duct 215 is generated, causing a flow of combustion gas FCG to flow into the gas mixing device 210, thereby creating a combustible combustion gas / air mixture flow FCGA. In other words, the throttle element 100 may be understood as a temporary Venturi-effect enhancing device. For small flows F through the flow channel 12, the Venturi-effect of the gas mixing device 210 alone would not be sufficient to suck in sufficient parts of combustion gas from the combustion gas feed duct 215 to create a combustible combustion gas / air mixture. This may for example be the case, if the combustion gas utilized comprises a combustion gas of low calorific value. Vice versa, with increasing flow rates of the flow F through the flow channel 12, the flap 14 becomes more and more obsolete, as the gas engine 200 reaches its nominal operation. Accordingly, the flap 14 self adjusts as a function of the flow F through the flow channel 12, such that the flow cross-section A becomes large and the opening angle becomes large correspondingly. At a given point, the Venturi-effect provided by the gas mixing device 210 alone may be sufficient to suck in sufficient parts of combustion gas from the combustion gas feed 215 to create a combustible combustion gas / air mixture. In this scenario, the flap 14 may have only a negligible effect on the flow F through the flow channel 12.

The throttle element 100 may be a section of the air intake duct 220 of the gas engine 200. To this end, the throttle element 100 may further comprise a damping element 18 and/or an actuator 20 (not shown in Figure 3). More specifically, the housing 10 of the throttle element 100 may be a part or integrated into the air intake duct 220 of the gas engine.

The combustion gas comprised in the combustion gas flow FCG may comprise a low calorific gas having a calorific value of equal or less than 25 MJ/m ³ , in particular equal or less than 8.5 MJ/m ³ .

Further, the air intake duct 200 may comprise a manifold 230 having at least a first manifold duct 232 and a second manifold duct 234. According to the embodiment shown in Figure 3, the throttle element 100 may be provided in the air intake duct 220 at a proximal end 221 of the air intake duct 220 adjacent to the gas mixing device 210. In addition, the gas engine 200 may further comprise an air filter 236 upstream of the throttle element 100. According to the embodiment shown in Figure 3, two air filters 236 are provided at the end of the first manifold duct 232 and the second manifold duct 234.

Figure 4 shows another embodiment of the gas engine 200. According to this embodiment, the throttle element 100 may be provided in the air intake duct 220 at a distal end 222 of the air intake duct 220 away from the gas mixing device 210. Apart from this difference, the embodiment shown in Figure 4 may be identical to the embodiment shown in Figure 3 and thus, the same principles may apply. The embodiment shown in Figure 4 may have the advantage that the flow reaching the gas mixing device 210 may be smooth, free of eddies, thus providing a more homogeneous admixing of combustion gas via the combustion gas feed duct 215.

Figure 5 shows an even further embodiment of the gas engine 200. According to this embodiment, the air intake duct may comprise a manifold 230 having at least a first manifold duct 232 and a second manifold duct 234, wherein the throttle element 100 may comprise a first flap 141 in the first manifold duct 234 and a second flap 142 in the second manifold duct 234. Further, the first flap 141 and the second flap 142 may be operatively coupled with each other. In addition, the gas engine may further comprise an air filter 236 upstream of each of the throttle elements 100. Thereby, the air flow can be throttled immediately after the air filter 236, allowing to use the entire length of the air intake duct 210 to yield a smooth Venturi flow Fv prior to entering the gas mixing device 210.

It will be obvious for a person skilled in the art that these embodiments and items only depict examples of a plurality of possibilities. Hence, the embodiments shown here should not be understood to form a limitation of these features and configurations. Any possible combination and configuration of the described features can be chosen according to the scope of the invention. This is in particular the case with respect to the following optional features which may be combined with some or all embodiments, items and all features mentioned before in any technically feasible combination. As an example, there may be more than one flap provided in a flow channel. Further, there may be more than one throttle elements provided in an air intake duct arranged in a subsequent manner. In addition, there may be more than a first and a second manifold ducts comprise by the air intake duct of the gas engine.

A throttle element for an intake duct of a gas engine may be provided. The throttle element may comprise a housing having a flow channel and a flap mounted therein. The flap may be configured such that a flow cross- section of the flow channel is self-adjusting as a function of a flow through the flow channel.

In other words, the flap mounted in the flow channel may be passively actuated, meaning actuated only by the flow through the channel without requiring further adjusting means. Thereby, a simple, failsafe and cost- efficient adjustment of the flow cross-section of the flow channel may be achieved. By configuring the flap such that a flow cross-section of the flow channel is self-adjusting as a function of a flow through the flow channel, a sufficient negative pressure downstream of the throttle element may be achieved. Thereby, a Venturi effect may be established for flows which would normally be too small for yielding a sufficient Venturi effect if no throttle element according to the present disclosure was present. Further, for flows high enough for yielding a sufficient Venturi effect if no throttle element according to the present disclosure was present, the flap may only have a negligible effect on the flow. According to a preferred embodiment, the flap may be configured to be openable by an opening angle wherein the flow cross-section of the flow channel may depend on the opening angle. By configuring the flap such that it is openable by an opening angle, the effective flow cross-section may conveniently be calculated as a function of the opening angle. As a result, a simple correlation between the flow through the flow channel, the opening angle and the effective cross-section of the flow may be established. To this end, operation of the throttle element may easily be calibrated, monitored and/or predicted.

According to a further development, the flap may be configured to be pivotable about an axis of rotation running transversely to a direction of the flow through the flow channel. Thereby, a mechanically simple, reliable and cost- efficient installation of the flap within the flow channel of the throttle element may be achieved.

According to a further development, the flap may be configured such that the flow cross-section increases with increasing flow through the flow channel and decreases with decreasing flow through the flow channel, wherein, in a state when no flow is flowing through the flow channel the flow cross-section is very small or almost zero. By configuring the flap such that the flow cross- section increases with increasing flow, the flap may be configured or provided such that it provides a resistance surface against the airflow inside of the flow channel.

As an example, the flap may be configured such that it is held in a closed position by gravitational forces. Acting on the flap, the momentum of the flow inside the flow channel may then push the flap open and establish a flow cross-section in the flow channel. In a further development, the throttle element may comprise a damping element configured to dampen a movement of the flap such that natural oscillation of the flap is avoided, wherein the damping element comprises an electric, hydraulic and/or mechanical component. The damping element may be adjusted. Thereby, a potential detrimental impact of the flap through the flow through the flow channel may be minimized. Further, noise and/or vibration emissions may be reduced, leading to a smoother operation of the throttle element and a gas engine to which the throttle element is installed.

According to a further development, the throttle element may comprise an actuator configured to actuate the flap, wherein the actuator comprises electrical and/or mechanical actuation means. To this end, the actuator is configured such that it still allows a passive, or self-adjusting, operation of the throttle element and may only act as an optional means of actuation. Alternatively or additionally, the actuator may be configured such that it supports, secures and/or enhances a movement of the flap.

In a preferred development, the flap may be designed to be self- adjusting as a function of a flow through the flow channel consisting only of air. Thereby, the dimensions, material properties and surface qualities of the flap may specifically be configured such that they are optimized specifically for air within an expected and/or possible mass flow of air through the flow channel. Flow characteristics like the dimensions of boundary layers, laminar and turbulent flow regions may be established effectively for the material properties of air. Thereby, the overall operation of the throttle element may be optimized.

A gas engine comprising a gas mixing device in an air intake duct and a throttle element provided upstream of the gas mixing device may be provided. The throttle element may comprise a housing having a flow channel and a flap mounted therein. The flap may be configured such that a cross-section of the flap is self-adjusting as a function of a flow through the flow channel. Thereby, for a wide range of flows through the flow channel, a sufficient negative pressure in be achieved downstream of the throttle element. Thereby, the gas mixing device may be able to admix combustion gases for a wide range of flow rates of the flow flowing through flow channel.

According to a preferred development, the gas mixing device may be of the Venturi type in may be configured to admix at least one combustion gas through the flow through the flow channel. Thereby, a simple, cost-effective and reliable means of admixing combustion gases to air may be provided.

In a preferred development, the at least one combustion gas may comprise a low calorific gas having a calorific value of equal or less 25 MJ/m ³ , in particular equal or less than 8.5 MJ/m ³ . In general, according to the context of the present disclosure, the term low calorific value refers to a combustion gas with which the gas engine is known to have troubles starting. For example, a combustion gas having a low calorific value may be a gas outside of the lambda window of a gas engine at a shaft rotation of 100-150 rpm. In a preferred development, the air intake duct may comprise a manifold having at least a first manifold duct and a second manifold duct, wherein the throttle element may comprise a first flap in the first manifold duct and a second flap the second manifold duct. By providing a manifold having at least a first manifold duct and a second manifold duct, the air intake surface may be spread out to a wider range which allows to have slower flow velocities in the filter stages and thus an improved filtering. By comprising a first flap in the first manifold duct and a second flap in the second manifold duct, the entire length of the air intake duct is downstream of the flaps. Thereby, turbulences inflicted to the flow by the flaps may be smoothed before the flow reaches the gas mixing device. Thereby, the admixing of combustion gases may be realized in a more reliable and continuous manner.

In a preferred development, the first flap and the second flap may be operatively coupled with each other. Thereby, restriction of the flow cross- section may be achieved in a more reliable way. Accordingly preferred development, the throttle element may be provided in the air intake duct a proximal end of the air intake duct adjacent to the gas mixing device or as a distal end of the air intake duct away from the gas mixing device. Providing the throttle element in the air intake duct at a proximal end of the air intake duct has the advantage that flow interaction between the gas mixing device and throttle element occurs quicker. Providing the throttle element the air intake duct a distal end of the air intake duct away from the gas mixing device, has the advantage that the flow reaching the gas mixing device has reduced fluctuations and turbulence is, leading to an overall smooth a at mixing performance.

In a preferred development, the throttle element may comprise a damping element. More precisely, the throttle element may comprise a damping element configured to dampen a movement of the flap such that natural oscillation of the flap is avoided, wherein the damping element comprises an electrical, hydraulic and/or mechanical component. Thereby, a potential detrimental impact of the flap through the flow through the flow channel may be minimized. Further, noise and/or vibration emissions may be reduced, leading to a smoother operation of the throttle element and a gas engine to which the throttle element is installed. According to a preferred development, the gas engine may further comprise an air filter upstream of the throttle element. Thereby, solid and/or liquid particles or gases impurities can be filtered out effectively from the air to be sucked into the air intake duct before entering said air intake duct.

Industrial Applicability With reference to the figures, a throttle element and gas engine having a throttle element are provided.

In practice, a throttle element and a gas engine comprising such a throttle element may be manufactured, bought, or sold to retrofit an engine, or in engine already in the field in an aftermarket context or alternatively may be manufactured, bought, sold or otherwise obtained in an OEM (original equipment manufacturer) context.

As alluded to previously herein, the aforementioned embodiments may increase the startup performance of gas engines as will be elaborated further herein momentarily.

Referring to Figure 1, there is an embodiment shown, disclosing a throttle element comprising a flap which is configured such that a flow cross- section of a flow channel is self-adjusting as a function of a flow through the flow channel. One skilled in the art will expect that various embodiments of the present disclosure will have an improved simplicity, necessitating less maintenance and less complex geometries.

The same advantages apply to the Figure 2, in particular to the throttle element comprising an actuator and to the engine comprising such a throttle element and further to the Figures 3-5, comprising a gas engine comprising one or more throttle elements provided upstream of a gas mixing device.

The present description is for illustrative purposes only and should not be construed to narrow the breadth of the present disclosure in any way.

Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” “include”, “includes”,

“including”, or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

Certain steps of any method may be omitted, performed in an order that is different than what has been specifically mentioned or in some cases performed simultaneously or in sub-steps. Furthermore, variations or modifications to certain aspects or features of various embodiments may be made to create further embodiments and features and aspects of various embodiments may be added to or substituted for other features or aspects of other embodiments in order to provide still further embodiments.

Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.