FR2794800A1 - COMBUSTION INTERNAL COMBUSTION ENGINE, OPERATING WITH A GASEOUS FUEL - Google Patents

Abstract

A supercharged internal combustion engine, operating with a gaseous fuel, has several combustion chambers, at least one pipe and at least one casing for the supply of supercharging air to the combustion chambers. With each combustion chamber (7)) is associated at least one gas supply valve (5) for supplying gas to the respective combustion chamber (7). The at least one housing (2) or the at least one line (13) for supplying charge air is subdivided (e), by at least one separating element (10), into at least two chambers (2a, 2b ) with associated flow inlet channels (11a, 11b), or else in at least two conduits (13a, 13b).

Description

Supercharged internal combustion engine. running on fuel

  The invention relates to a supercharged internal combustion engine, operating with a gaseous fuel, of the type

  defined in more detail in the preamble of claim 1.

  Such internal combustion engines, which are also called gas engines and, in particular, are used in utility vehicles, are known from the general state of the art. To be able to obtain greater power, in most cases they are equipped with a turbocharger driven by the exhaust gases and are then qualified as

supercharged internal combustion.

  Most of the time, such internal combustion engines have a charge air casing, in front of the latter, in the charge air tube, the mixture is formed, by mixing with the gas charge air, supplied by means of a gas supply device or a gas mixing device. By means of the charge air casing and the inlet channels connected to it, the homogeneous air-gas mixture generated is individually brought to the combustion chamber.

of the internal combustion engine.

  Internal combustion engines having this type of gas mixture, however, have a relatively inert reaction behavior, since the path which leads the air-gas mixture from carburetion to the combustion chamber is relatively long. Another problem with today's internal combustion engines is the more or less irregular distribution of the air-gas mixture to the different combustion chambers. This leads to a disadvantageous efficiency of the internal combustion engine, knowing that the problem increases even more when one has a more strongly boosted supercharging. Due to the poor and uneven distribution of the air-gas mixture towards the combustion chambers, drawbacks are also obtained, concerning the emissions emitted by the internal combustion engine, due to the fact that the ignition point concerned for the emissions and for the efficiency, the mixture in the respective combustion chamber, cannot be adjusted jointly for all the combustion chambers and that here always take into account the flammability of the combustion chamber

most disadvantageous combustion.

  The aim of the present invention is to create a supercharged internal combustion engine, operating on a gaseous fuel, which exhibits better reaction behavior, better efficiency and a lower rate of emission of harmful substances to internal combustion engines. supercharged known so far,

  operating on gaseous fuel.

  According to the invention, this problem is solved by the properties indicated in the characterizing part of the

claim 1.

  Thanks to the association of at least one gas supply valve to each specific combustion chamber of the internal combustion engine, a separate carburetion is obtained for each combustion chamber. This advantageously makes it possible to obtain a more regular distribution of the gas or of the fuel towards the different combustion chambers. The expulsion of harmful substances and the performance of this internal combustion engine depend on the combustion air ratio and the timing of ignition, which are involved in a relationship depending on the ignition capacity of the air-fuel mixture. . For this reason, for each operating state of the internal combustion engine, an optimum ratio of combustion air must be sought in all the combustion chambers. Thanks to the separating element according to the invention, which subdivides the casing or the charge air supply pipe into at least two chambers with associated flow inlet channels, or else into at least two pipes, the influence exerted on the suction timing of a combustion chamber by the other combustion chambers is minimized, which leads to obtaining a regular distribution of the charge air to all the combustion chambers for achieve identical combustion air conditions in all the

combustion.

  One can for example, for an internal combustion engine having six combustion chambers, each time group three combustion chambers which do not ignite directly one after the other with a chamber for supplying charge air, so that the '' we minimize any mutual influence between the timing of suction of the different combustion chambers by the

  air flows and air vortices.

  The time spacing at which the air-fuel mixture is ignited in one chamber, while it is in two successive combustion chambers, can be precisely provided so that it is greater than the respective opening time of the pressure valves. admission of the different combustion chambers. Therefore, the air-gas mixture which is in an intake channel can only reach the combustion chamber each time provided for this. Thus, the supply of the same amount of air and gas to each combustion chamber is obtained, which ensures very good combustion. By adopting the shortest paths, which the gas must travel from the place of its carburation to the combustion chambers, we obtain a faster reaction behavior and thus better dynamics of the

internal combustion engine.

  Advantageous embodiments and improvements of the invention result from the following

  claims, as well as exemplary embodiments

  shown in principle below using the drawing.

  In the drawing: FIG. 1 is a top view of an internal combustion engine according to the invention; FIG. 2 is a top view shown schematically of an alternative embodiment of the internal combustion engine according to the invention; Fig. 3 is a section along line III-III of FIG. 1; and Fig. 4 is a sectional representation similar to FIG. 3, with a variant arrangement of the

gas supply valve.

  In Fig. 1 is shown in top view of an internal combustion engine 1 with six cylinders, operating with a gaseous fuel. The internal combustion engine 4 provided for commercial vehicles, which can theoretically also be used for passenger cars, is supercharged by means of a turbocharger driven by the exhaust gases, not shown, and has for this purpose a casing 2 for the supply of charge air into intake channels 3, housing designated hereinafter as the charge air housing 2. The intake channels 3 are shown in FIGS. 3 and 4. With regard to gas, it may for example be natural gas or else liquid gas. In addition, on the internal combustion engine 1 is arranged a gas supply pipe 4 for supplying gas.

gas supply valves 5.

  The gas supply line 4 extends over the entire length of the internal combustion engine and is connected to each gas supply valve 5. The gas, upon expansion, is again cooled and is supplied to the engine with internal combustion 1 at a relatively low temperature, which leads to a lower mixing temperature and, thus, to a higher efficiency of the internal combustion engine 1. This is reflected for example by the fact that, for the same quantity expelled NOx, we choose a time

earlier for ignition.

  The arrangement of the gas supply valves 5 is better visible in Figs. 3 and 4, the variants being distinguished by the operating mode of the gas supply valves 5. In the embodiment of FIG. 3, each gas supply valve 5 sends gas withdrawn from the gas supply line 4 using the pulse of the expanded gas, directly into the respective intake channel 3, which leads to an intake valve 6, known per se, and in a combustion chamber 7, when the intake valve 6 is in the open position. The combustion chamber 7 is, in known manner, inside a cylinder head 8 of the internal combustion engine 1, in which the intake valve or several intake valves 6 are arranged. It would alternatively also be possible to arrange the intake valves of

gas 5 in cylinder head 8.

  In the embodiment of FIG. 4, the gas supply pipe 4 is integrated in the charge air casing 2 and is produced in the form of a bore 4 extending at least roughly over the entire length of the internal combustion engine 1 , hole arranged below the gas supply valves 5 and supplying the latter with gas. A sampling or tapping hole 9 starts from the gas supply valves 5 and leads each time into the intake channel 3. The rest of the arrangement

corresponds to that of FIG. 3.

  In both embodiments, the mixture formation, therefore the mixing of the gas supplied by the gas supply valves 5 with the air supplied by the charge air casing 2, is thus already partially in the inlet channels 3. The two embodiments also have in common that the gas supply valves 5 are arranged in the charge air casing 2. In any case it would also be possible to adopt a arrangement of these in the

cylinder head 8.

  Since the internal combustion engine 1, as already mentioned above, has six combustion chambers 7, generally six supply valves have been provided

gas 5.

  As can be seen again in FIG. 1, in the charge air casing 2 there is a separating element 10 by means of which the air casing of

  supercharging 2 is subdivided into two chambers 2a and 2b.

  In other words, the charge air casing 2 is made with two flows. The separating element 10 is made in the form of a dividing wall and extends to an inlet zone, produced in the form of an inlet channel 11 of the charge air casing 2, which is also subdivided separator 10. In the inlet zone into the charge air casing 2, the chambers 2a and 2b are mounted upstream as well as the flow inlet channels 11a and 11b. The flow inlet channels 11a and 11b are here designed so as to prevent any direct flow arrival from the charge air inlet channels in the inlet channels

admission 3.

  The chambers 2a and 2b have at least approximately the same volume, which ensures that each time the same air ratios are supplied to the individual combustion chambers 7, during the suction stroke. The metering of the identical quantity of gas for each combustion chamber 7 is ensured by the gas supply valves 5 by the withdrawal of the gas from the supply line of

gas 4 common.

  The injection of the charge air into the two chambers 2a and 2b takes place here in a manner approximately parallel to the longitudinal axis of the internal combustion engine 1, so that any direct flow arrival in the different inlet channels 3 and almost identical filling of the combustion chambers 7 is ensured by almost identical air ratios

in rooms 2a and 2b.

  The charge air casing 2, as well as the gas supply pipe 4 connected thereto, can for example be manufactured according to a sand casting process, from aluminum, and jointly constitute a modular component which, like shown in Fig. 3 and FIG. 4, can be easily mounted with screws 12

  on cylinder head 8 or on cylinder heads 8 of different types.

  In a manner not shown, it is also possible to integrate, the electrical conduits intended for the control of the gas supply valves 5 in the charge air casing 2. The size of the charge air casing 2 makes it possible to have a large volume of charge air, which ensures good filling and

  regular combustion chambers 7.

  To prevent any influence of the supply of the mixture on the combustion chambers 7 associated with one of the chambers 2a or 2b, each of the chambers 2a or 2b are not

  each associated with only three combustion chambers 7.

  The inlet valves 6 are open for bringing the air-gas mixture to the combustion chambers 7 only to a maximum value of 240 during a crankshaft angle, knowing that the air-gas mixture flows in the combustion chambers combustion 7 due to the fact that the intake valves 6 are in the open position. For an overall crankshaft angle of 7200 Dar cycle of the internal combustion engine 1 so each time only the intake valves 6 of a combustion chamber 7 by chambers 2a or 2b is open and an evacuation by suction of the air-gas mixture provided for a specific combustion chamber 7 is prevented by means of the air flow supplied to another combustion chamber 7. In general, it is always necessary only to associate a number of combustion chambers. 7 to one of the chambers 2a or 2b such that the spacing between the ignitions of the combustion chambers 7, associated with the chambers 2a or 2b, is less than the time of opening of the intake valves 6, bearing in mind that, concerning the opening time, valve strokes 10% lower than the

  overall valve stroke is not critical.

  There is shown in FIG. 2 an internal combustion engine 1 equipped with eight combustion chambers 7 in V. Here, as in the embodiment of FIG. 1, a line called the charge air line 13 leads in this case to two charge air housings 2a and 2b. In the charge air line 13 is also disposed the separating element 10 and it divides the latter thus into two lines 13a and 13b. In doing so, we have an association between the two air housings of

  supercharging 2a and 2b and the two lines 13a and 13b.

  As an alternative to this, it would also be possible, for internal combustion engines 1 equipped with combustion chambers 7 arranged in a V, to provide only one common charge air casing 2 and to produce this with several flux. The charge air casing 2 could then have one or more separating elements 10 which can subdivide the casing

  charge air 2 in two chambers 2a, 2b, 2c ...

or more.

  In the case of an internal combustion engine 1 having four combustion chambers 7, the charge air casing 2 could also be provided with the separating element 10 and two combustion chambers 7 could be associated with each of the chambers 2a or 2b. Based on the small number of combustion chambers 7, it would in any case also be possible not to provide any separating element 10 because the influence, following the large spacing between the ignitions of an angle of 180 of crankshaft for a simultaneously determining valve opening time of 180–200 crankshaft angle, could be minimized by adopting

building arrangements.

  As already mentioned above, there is in the intake channel 3 mixture formation due to the charge air supplied to the charge air casing 2 and the gas introduced into the intake channel 3 by the gas supply valve 5. To obtain a certain mixture between the gas and the air already before the introduction of the air-gas mixture into the combustion chamber 7, the gas supply valve 5 is open for a period determined before the intake valve 6 and also the closing of the gas supply valve 5 takes place before the closing of the intake valve 6. Thanks to what is called this displacement offset, brings to the combustion chamber 7 first only air, then a relatively rich air-gas mixture, and finally again only air. This ensures that all of the gas arrives in the combustion chamber 7 and that there is no loss of sweep, concerning the gas, by the fact that there is

valve cycles crossing.

  To observe the thermodynamic state of the gas in the gas supply line 4, a gas temperature sensor 14 and a gas pressure sensor 15 are arranged therein, in order to measure the gas temperature and the pressure of gases, sensors, the measurement values of which can be brought to a control or regulation unit, not shown, of the internal combustion engine 1. Furthermore, a charge air sensor 16 is provided for measuring the temperature and the pressure of the charge air which in this case is arranged in the chamber 2a. These measurement values are used for calculating and adjusting the

  optimal combustion air ratio.

  In the present internal combustion engine 1, working according to the Otto principle, the mass air flow is regulated by means of a throttling device not shown. Depending on the operating state of the internal combustion engine 1, this leads to more or less significant throttling losses and, thus, to degradations of the efficiency. To increase the efficiency, the mass air flow is regulated in the medium and high load range of the internal combustion engine 1, by means of the exhaust gas turbocharger, already mentioned above, which have a geometry variable turbine. The turbocharger driven by the exhaust gases must here convey only the quantity of air necessary for the internal combustion engine 1, so that the thermodynamic process is supplied with more energy from the exhaust gases and that there is no loss

  the throttling system.

Claims (9)

  1. Supercharged internal combustion engine, operating with a gaseous fuel, having several combustion chambers, at least one pipe and at least one housing for supplying charge air to the combustion chambers, characterized in that at each combustion chamber (7) is associated with at least one gas supply valve (5) for supplying gas to the respective combustion chamber (7), and in that the at least one casing (2) or the at least a charge air supply pipe (13) is subdivided by at least one separating element (10) into at least two chambers (2a, 2b) with flow inlet channels (lla , llb) associated, or at least two pipes (13a, 13b).   2. Internal combustion engine according to claim 1, characterized in that the flow inlet channels (lla, llb) are produced so as to prevent any direct flow of charge air flow. to the input channels (3).   3. Internal combustion engine according to claim 2, characterized in that the different chambers (2a, 2b)   each have at least about the same volume.   4. Internal combustion engine according to one of   claims 1, 2 or 3, characterized in that at least one   gas supply line (4) is provided for supplying   gas to the gas supply valves (5).   5. Internal combustion engine according to claim 4, characterized in that the at least one gas supply pipe (4) is produced in the form of a bore formed in   the casing (2), for the supply of charge air.   6. Internal combustion engine according to claim 4, characterized in that the at least one gas supply pipe (4) is produced in the form of a pipe, arranged 12 -   separately on the housing (2), for the supply of charge air. 7. Internal combustion engine according to one of   claims 4, 5 or 6, characterized in that the pipe   gas supply (4) constitutes, together with the housing (2), a modular component for supplying charge air. 8. Internal combustion engine according to one of   Claims 1 to 7, characterized in that the valves   gas supply (5) are arranged inside the   casing (2) for the supply of charge air.   9. Internal combustion engine according to one of   Claims 1 to 8, characterized in that at the   combustion (7), which are lit directly one after the other, are each associated with different rooms (2a or 2b).