WO2014166534A1

WO2014166534A1 - Gas mixture detection module for liquefied gas for motor vehicles

Info

Publication number: WO2014166534A1
Application number: PCT/EP2013/057499
Authority: WO
Inventors: Werner Gieger
Original assignee: Intec Ag
Priority date: 2013-04-10
Filing date: 2013-04-10
Publication date: 2014-10-16
Also published as: EP2984320A1

Abstract

A device (1) and a method are used to determine the mixing ratio of a liquefied gas mixture (2), in particular autogas (LPG). The gas mixture (2) is intended for combustion in an engine (19) and is fed to the engine from a gas tank (3). A temperature sensor (8) measures the temperature of the liquefied gas mixture (2). A pressure sensor (9) is used to measure the pressure of the gas mixture (2) in the gas tank (3). The measured values of the temperature and of the pressure are fed to a gas mixture detection module (7) connected to the temperature sensor (8) and to the pressure sensor (9). From the measured values of the temperature and of the pressure, the gas mixture detection module (7) determines the current mixing ratio of the gas mixture (2) on the basis of saturation vapour pressure curves (20) for various mixing ratios of the gas mixture (2). The gas control unit (13) is controlled as a function of the current mixing ratio of the gas mixture (2) in order to ensure optimal combustion during the gas combustion operation without the petrol combustion operation being negatively affected.

Description

GAS MIXING MODULE FOR LIQUID GAS FOR MOTOR VEHICLES

TECHNICAL FIELD OF THE INVENTION

The invention relates to a device and a gas mixture detection module for determining the mixing ratio of a liquid gas mixture, wherein the gas mixture is intended for combustion in an engine. The invention further relates to a method for controlling a motor operated with a liquid gas mixture.

The gas mixture is liquefied gas, d. H. a propane and butane-containing gas mixture. LPG is also commonly referred to as LPG ("Liquefied Petroleum Gas") or LPG. Such LPG can be used for combustion in gasoline engines commercially available vehicles. Other applications include combustion in engines of boats or work machines or in combined heat and power plants.

STATE OF THE ART

From the German patent application DE 10 2004 044 178 A1 an apparatus and a method for controlling the fuel injection for an engine with LPG injection are known. The mixing ratio of propane and butane in the LPG is determined to control the fuel injection time and the fuel injection period by a map depending thereon. For this purpose, the temperature and the pressure of the liquefied gas is determined, the pressure being determined by means of a fuel pressure sensor already present in the engine. The determination of the propane content depends on a speed, which is referred to in this document of the prior art as "engine speed". However, in the opinion of the applicant, this is obviously not the speed of the motor of the motor vehicle, but of the gas fuel pump. Because the pressure sensor is downstream is arranged by the gas fuel pump, in the determination of the mixing ratio of the gas mixture and the difference in speed between the off state and the on state of the motor vehicle (and thus the gas fuel pump) must be considered. In other words, the gaseous fuel feed pump has an effect on the measured pressure and must be eliminated by depositing a specific table for the gas fuel pump used. The mixing ratio of the gas contents of the fuel is calculated once at the initial starting of the vehicle.

Another device and a method for determining the mixing ratio of a liquid gas mixture are known from the German patent applications DE 24 04 557 and DE 36 15 679 A1. The mixing ratio of the gas mixture consisting of butane and propane is determined on the basis of the pressure and the temperature of the gas mixture. The liquefied gas is vaporized in a pressure regulator / evaporator and introduced into the combustion chamber in the vapor state. The pressure of the gas mixture is determined in the pressure regulator / evaporator by means of a mechanical-pneumatic flap control. The measurement does not take place in the sense of defined individual measurement processes, but by a permanent pressure equalization control.

The German patent DE 10 2006 022 357 B3 shows a method and a device for determining the mixing ratio and for controlling the engine of a motor vehicle in the combustion of natural gas. The natural gas has as its main component a gaseous component - namely methane - on. It should continue to have liquid ingredients - especially ethane, propane and butane - have. The gaseous components are removed from the tank. In the first taking place of methane, the pressure prevailing in the tank decreases accordingly. Later, the other constituents of the mixture should change from the liquid to the gaseous state and the mixing ratio should then be determined.

From the document HTTP://WWW.MOTOR-TALK.DE/FORUM/VAMPFDRUCK-UR- FORM-MIXING-PB-95-5-BIS-30-70-T1403005.HTML of March 30, 2007, it is known that the temperature and the pressure of liquefied gas may be used by using saturation vapor pressure curves to determine the mixing ratio of propane and butane. The mixing ratio should be determined for the LPG in the tank of a dispenser. German patent application DE 10 2011 111 390 A1 discloses a method and a device for determining the mixing ratio of liquefied gas.

From the German patent application DE 44 46 081 A1 discloses a fuel control system for an internal combustion engine of motor vehicles is known, which performs an approximation of the fuel quantity via a detected pressure and temperature signal to the gas injection nozzle for compressed gas. A gas quantity adjustment of the gas quantity to be injected or injected in relation to the temperature present at the gas nozzle and the gas pressure applied by the pressure reducer is achieved by means of a stored characteristic map.

OBJECT OF THE INVENTION It is the object of the invention to provide a device and a method with which the mixing ratio of a liquid gas mixture can be reliably and universally determined and the engine combusting the gas mixture can be regulated as a function of this under permanent compliance with the permissible exhaust gas values.

SOLUTION The object of the invention is achieved with the features of the independent patent claims.

Further preferred embodiments according to the invention can be found in the dependent claims.

DESCRIPTION OF THE INVENTION The invention relates to an apparatus for determining the mixing ratio of a liquid gas mixture of a first liquid gas and a second liquid gas. The gas mixture is intended for combustion in an engine and is supplied to it from a gas tank. The apparatus includes a temperature sensor for measuring the temperature of the liquid gas mixture, a pressure sensor for measuring the pressure of the gas mixture in the gas tank, and a gas mixture detection module connected to the temperature sensor and the pressure sensor. The gas mixture detection module is the measured values of temperature and pressure. Based on saturation vapor pressure curves for different mixing ratios of the gas mixture, the gas mixture detection module determines the current mixing ratio of the gas mixture.

The invention further relates to a gas mixture detection module for determining the mixing ratio of a liquid gas mixture of a first liquid gas and a second liquid gas. The gas mixture is intended for combustion in an engine and is supplied to it from a gas tank. The mixed gas detection module is configured and configured to receive a value of the pressure of the gas mixture in the gas tank and the temperature of the liquid gas mixture. The gas mixture recognition module is designed and determined for determining the actual mixing ratio of the gas mixture by comparing the measured values of the temperature and the pressure of the gas mixture with the corresponding values in saturation vapor pressure curves for different mixing ratios of the gas mixture.

The invention also relates to a method for determining the mixing ratio of a liquid gas mixture of a first liquid gas and a second liquid gas. The gas mixture is intended for combustion in an engine and is supplied to it from a gas tank. The method comprises the following steps:

Measuring the temperature of the liquid gas mixture with a temperature sensor,

Measuring the pressure of the gas mixture in the gas tank with a pressure sensor, transmitting the measured values of the temperature and the pressure of the gas mixture to a gas mixture detection module, and

- Determining the mixing ratio of the gas mixture with the gas mixture detection module by comparing the measured values of the temperature and the pressure of the gas mixture with the corresponding values in saturation vapor pressure curves for different mixing ratios of the gas mixture.

The invention further relates to a method for controlling an engine operated with a liquid gas mixture, wherein the liquid gas mixture comprises a first liquid gas and a second liquid gas. The method comprises the following steps: Measuring the temperature of the liquid gas mixture with a temperature sensor,

Measuring the pressure of the gas mixture in a gas tank with a pressure sensor,

Transferring the measured values of the temperature and the pressure of the gas mixture to a gas mixture detection module,

Determining the mixing ratio of the gas mixture with the gas mixture detection module by comparing the measured values of the temperature and the pressure of the gas mixture with the corresponding values in saturation vapor pressure curves for different mixing ratios of the gas mixture, and controlling a gas control device to adapt to the current mixing ratio of the gas mixture; Gas control unit has a Gaseinblas- or gas injection times containing map, wherein the Gaseinblas- or gas injection times are set in dependence on the current mixing ratio of the gas mixture.

Definitions Gas mixture: In this application, a gas mixture is understood as meaning a mixture of at least two different gases. However, the gas mixture may also contain three, four or more different gases, it being possible to also determine the proportions of these other gases in the gas mixture or to neglect them. The proportions are determined in percent by volume. Further description

The new device, the new gas mixture detection module and the new methods are universally applicable to many different vehicles and can be retrofitted. This applies both to an injection of the liquid gas and an injection of the gaseous gas. The present invention is applicable to all common gas mixture combustion plants, in particular venturi plants, semi-sequential plants, fully sequential plants and liquid gas injection plants. The respective type of system must be taken into account when arranging the sensors. In a liquefied gas injection, the sensors are arranged in the gas tank or arranged in the so-called multi-valve. Downstream there are no representative values for LPG injection because the LPG delivery pump pressure and the temperature are distorted by the engine radiating heat.

There is no dependency on the particular engine used, since pressure and temperature are determined independently of influencing variables of the respective engine. The temperature sensor measures the temperature of the liquid gas mixture. For this purpose, it can be arranged in particular in the gas tank, a pipe leading away from it or the gas mixture detection module. The pressure sensor is used to measure the pressure that the gas mixture has in the gas tank. In this case, the pressure sensor itself need not be arranged in the gas tank, but merely measure the pressure prevailing in the gas tank. Therefore, the pressure sensor so downstream of the gas tank in a line or z. B. the gas mixture detection module, which are connected in terms of pressure with the gas tank, so that the pressure prevailing in the gas tank pressure also applied there and thus is measurable.

The measured values of temperature and pressure are then fed as analog or digital electrical signals via corresponding lines to the gas mixture detection module. The gas mixture detection module is programmed to have saturation vapor pressure curves for different mixing ratios of the gas mixture. The saturation vapor pressure is known to be the vapor phase pressure of a substance when the liquid and vapor phases are in equilibrium. The pressure over a mixture of several different gases depends on the mixing ratio of the gases. On the basis of the determined pressure at a likewise determined temperature, therefore, the current mixing ratio of the gas mixture in volume percent can be determined.

The mixing ratio of the gas mixture changes, for example, from gas station to gas station and also from winter to summer, as more butane is contained in the gas mixture in summer. Since butane has a higher burning energy than propane, with a relatively larger proportion of propane more gas mixture per unit time in the engine must be burned. The mixed gas detection module is preferably configured to repeatedly perform the determination of the actual mixing ratio of the gas mixture at defined spaced time intervals. It is then not a matter of a permanent measurement in the sense of a pressure equalization control, but rather defined and temporally spaced measurements which are repeated several times. In particular, the time interval may be between about 5 seconds and 10 minutes, between about 20 seconds and 5 minutes, and preferably about 30 seconds.

The determination of the current mixing ratio of the gas mixture is thus carried out several times in succession after starting the engine with the engine running. This is preferably done over the entire operating life of the engine. This allows a much more accurate control of the gas control unit of the engine can be realized. By this new rule z. B. occurring during operation temperature fluctuations are well balanced. One reason for comparatively high temperature fluctuations is the arrangement of the gas tank of the vehicle outside of the vehicle, so that the airstream leads to a cooling of the gas tank and the gas mixture contained therein. Another reason is the parking of the vehicle in a garage and the subsequent operation at minus temperatures in winter or even in strong sunlight in the summer. Another reason for LPG injection is the return of the liquefied gas heated by the engine to the gas tank. These differences in temperature during operation lead to a change in the density of the gas mixture and thus require an adaptation of the characteristic map of the gas control unit, in order to continue to ensure optimum combustion and compliance with the exhaust gas values.

Another advantage of this repeated measurement and control even after starting the engine is that the gasoline control unit is not moved unintentionally. The gasoline control unit usually works in the gas mode permanently with. Normally, the gasoline injection signal is removed from the fuel injector and supplied to the gas controller. However, the fuel control unit is still connected to the lambda probe and receives from these values on whether the combustion was carried out properly and no partial combustion has occurred or is an over-greasing. This is also known as OBD (On Board Diagnostic) capability. The gasoline injection values in the gasoline control unit are thus continuously adapted, even if no injection of gasoline, but a gas combustion operation takes place. If now changes the gas quality in the gas combustion operation and the gas control unit - as usual in the art - not would be readjusted, an improper combustion would take place, they are reported by the lambda probe to the gasoline control unit and then perform the gasoline control unit, a readjustment. However, this readjustment would not be adjusted to the gasoline combustion - but to the gas combustion - and thus led to a misalignment of the gasoline control unit. At the next changeover to a gasoline combustion operation, for example, the next time the engine is started in gasoline combustion operation, the operation of the gasoline control apparatus would then occur with the gasoline control unit misaligned so that improper combustion would occur in gasoline combustion operation. The new multiple determination of the mixing ratio of the gas mixture during the gas combustion operation thus surprisingly also ensures that proper combustion takes place in a later gasoline combustion operation. In extreme cases, this can prevent the occurrence of engine damage, which would be done by operation of the engine with misalignment of the gasoline control unit. Moreover, according to the invention, the actual mixture ratio of the gas mixture (and a change of the same) can already be taken into account before any improper combustion occurs in the engine, which due to the current (changed) mixing ratio and the current mixing ratio is not or incorrectly taken into account. gas injection or gas injection times specified by the gas control unit. Thus, according to the invention, the control of the gas control device does not first take place as a function of the values of the lambda probe if it already signals an improper combustion, but "pro-actively" before the occurrence of improper combustion.

In this case, the "adjustment and regulation of the gas injection or gas injection times in dependence on the current mixing ratio of the gas mixture by the gas control device according to the invention so that the gasoline control unit is not adjusted". For example, a pure control taking into account the current mixing ratio, in particular under complementary Consideration of a dependent on the current mixing ratio gas map. Ideally, the gas mixture detection module always keeps the gas control unit set correctly, without any need for readjustment after a corresponding feedback from the lambda probe. As a result, the lambda probe constantly reports proper combustion to the gasoline control unit, leaving the gasoline control unit not adjusted in gas mode. The next time the engine is started in the gasoline combustion operation, there are thus proper maps in the gasoline control unit, so that the proper combustion in the gasoline combustion operation is ensured. In the context of the invention, however, it is quite possible that, in addition to the explained control, consideration of an output signal fed back from a lambda probe also takes place.

This operation can also be done as a so-called master / slave operation. The gasoline control unit is the master control unit and the gas control unit is the slave control unit. The gasoline control unit operates effectively, especially when starting the engine, wherein at a gas injection at a water temperature of about 30 ° C to 40 ° C of the pressure regulator / - evaporator is switched to the gas mode. The gasoline control unit then also works (ineffective, see above) in gas mode.

The liquid gas mixture has at least two different liquid gases, which are propane and butane. Experience has shown that the mixing ratio varies between approximately 5% and 95%. The higher the propane content, the higher the vapor pressure.

Depending on the determined values, the gas control unit u. a. with regard to the gas injection times (during the gas injection) or the gas injection times (during the gas injection). These and other values are contained in different gas maps depending on the mixing ratio of the gas mixture.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the introduction to the description are merely exemplary and can come into effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Without thereby altering the subject matter of the appended claims, as regards the disclosure of the original application documents and the patent, further features can be found in the drawings, in particular the illustrated geometries and the relative dimensions of several components and their relative arrangement and operative connection. The combination of features of different embodiments of the invention or features of different claims is also Deviating from the chosen relationships of the claims possible and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, features listed in the patent claims for further embodiments of the invention can be omitted.

The features mentioned in the patent claims and the description are to be understood in terms of their number that exactly this number or a greater number than the said number is present, without requiring an explicit use of the adverb "at least". If, for example, a temperature sensor is mentioned, this is to be understood as meaning that exactly one temperature sensor, two temperature sensors or more temperature sensors are present. If, on the other hand, only the exact number of a feature is to be specified, the adjective "exactly" before the respective feature is used.

BRIEF DESCRIPTION OF THE FIGURES

In the following, the invention will be further explained and described with reference to preferred embodiments shown in the figures.

Fig. 1 shows a view of a first exemplary embodiment of the new device in which the gaseous gas mixture is injected into the engine.

Fig. 2 shows a view of a second exemplary embodiment of the new device in which the liquid gas mixture is injected directly into the engine. Fig. 3 shows a view of a third exemplary embodiment of the new device in which the liquid gas mixture is injected into the intake passage of the engine.

4 shows a first saturated vapor pressure curve for a gas mixture with a proportion of propane of 20% and a proportion of butane of 80%. FIG. 5 shows a first gas map for the gas mixture according to FIG. 4. 6 shows a second saturated vapor pressure curve for a gas mixture with a proportion of propane of 40% and a proportion of butane of 60%.

FIG. 7 shows a second gas map for the gas mixture according to FIG. 6.

Fig. 8 shows a third saturated vapor pressure curve for a gas mixture with a proportion of propane of 50% and a proportion of butane of 50%.

FIG. 9 shows a third gas map for the gas mixture according to FIG. 8.

Fig. 10 shows a fourth saturated vapor pressure curve for a gas mixture with a proportion of propane of 85% and a proportion of butane of 15%.

FIG. 11 shows a fourth gas map for the gas mixture according to FIG. 10.

DESCRIPTION OF THE FIGURES

Fig. 1 shows a first exemplary embodiment of a novel device 1 for determining the mixing ratio of a liquid gas mixture 2 of at least a first liquid gas and a second liquid gas. The gas mixture 2 is liquefied gas, d. H. a gas mixture containing propane and butane 2. Such liquefied petroleum gas (LPG) is used in particular for combustion in gasoline engines of motor vehicles. However, other applications, such as combustion in engines of boats or cogeneration units, are also possible.

The device 1 has a gas tank 3, in which the gas mixture 2 is taken up in liquid form. Above the liquid level is the vaporous phase of the gas mixture 2. In the present case, the gas tank 3 is the gas tank of a motor vehicle which burns the gas mixture 2 in its engine 19. However, it could also be the gas tank 3 of a tanker truck or a gas station.

At the gas tank 3, a so-called multi-valve 4 is arranged. The multi-valve 4 provides various functions in a known manner, namely in particular an overfill protection, a withdrawal control, an overpressure control, a shut-off of the gas flow in the event of defecation. th lines and a level indicator. For the level indicator, the multi-valve 4 has a float 5. Furthermore, a line 6 is guided through the multi-valve 4 in the interior of the gas tank 3 and serves for sucking the liquid gas mixture. 2

Downstream of the multi-valve 4, the line 6 is then connected to a new gas mixture detection module 7. The gas mixture detection module 7 is in turn electrically connected to a temperature sensor 8 and a pressure sensor 9. In the embodiment of the gas mixture detection module 7 shown here, the temperature sensor 8 and the pressure sensor 9 are integrated in the housing of the gas mixture detection module 7, so that they are shown only schematically in the illustration of FIG. However, the sensors 8, 9 could also be arranged outside the housing of the gas mixture detection module 7.

From the gas mixture detection module 7, the line 6 is then continued to an evaporator / pressure regulator 10, which in turn is connected via line 6 with gas injection valves 1 1. The gas injection valves 1 1 are connected via an electrical line 12 with a gas control unit 13. The gas control unit 13 is in turn connected via electrical lines 14 to the gas mixture recognition module 7.

Another electrical line 15 connects the gas control unit 13 with a gasoline control unit 16. The gasoline control unit 16 is in turn connected via an electrical line 17 with gasoline injection valves 18. Both the gas injection valves 1 1 and the gasoline injection valves 18 are part of the engine 19, which, apart from the features resulting from the peculiarities of the present invention, is a conventional gasoline engine which has been converted for the combustion of liquefied petroleum gas , Accordingly, it is understood that both the gas injection valves 1 1 and the gasoline injection valves 18 serve to introduce the respective fuel into a common combustion chamber of the engine 19 and the illustration of FIG. 1 is thus only schematically in this respect. In the following, the various modes of operation of the engine 19 and the modes of operation of the new gas mixture detection module 7 will now be described in more detail: Gasoline operation

When the engine 19 burns gasoline in gasoline, this is introduced in the usual way by means of the gasoline injection valves 18 into the combustion chamber of the engine 19. The regulation of the gasoline injection valves 18 also takes place in the usual way by the gasoline control unit 16. It is understood that the gasoline is supplied via the fuel tank, not shown here.

The gasoline combustion operation may be active in particular when starting the engine 19. This is because the evaporator / pressure regulator 10 must first reach a certain operating temperature before it can be switched to the gas combustion operation. The gasoline control unit 16 is connected in a known manner with the lambda probe, not shown here, and receives from these values about whether the combustion was carried out properly. Depending on this, the gasoline injection values are constantly adjusted on the basis of gasoline maps in the gasoline control unit 16.

Gas combustion operation In gas combustion operation, the gas mixture 2 is now supplied to the combustion chamber of the engine 19 instead of gasoline. The supply takes place via the line 6, the multi-valve 4, the gas detection module 7, the evaporator / pressure regulator 10 and the gas blow valves 1 1. In this evaporator embodiment of the device 1 according to FIG. 1, the liquid gas flows into the evaporator / pressure regulator 10 and is converted into the gaseous state in this evaporator. The supply into the combustion chamber then takes place in the gaseous state via the gas injection valves 11.

In the prior art, in the gas combustion mode as well as in the gasoline combustion mode, only an adjustment of the supply of the respective fuel would then be carried out as a function of the signal of the lambda probe. Here, according to the invention, the new gas mixture detection module 7 comes into play, the function of which will be described further below. Gas mixture recognition

The new gas mixture detection module 7 is connected to the temperature sensor 8 and the pressure sensor 9. In the illustrated embodiment, the temperature sensor 8 is integrated into the housing of the gas detection module 7 and measures the temperature of the gas mixture 2 at its flow through the gas mixture detection module 7. However, the temperature sensor 8 could also be arranged another suitable location, as long as he can transmit his meaningful measurements to the gas mixture detection module 7.

The pressure sensor 9 is used to measure the pressure of the gas mixture 2. It is the pressure of the gas mixture 2, which prevails in the gas tank 3. This pressure could thus be measured as the saturation vapor pressure of the vaporous phase of the gas mixture 2 directly in the gas tank 3. However, the pressure can also be measured at a different location at which this pressure prevailing in the gas tank 3 pressure by the measuring location is connected in terms of pressure with the gas tank 3. In the present case, such a solution was selected and the pressure is measured by means of the pressure sensor 9 integrated into the gas mixture detection module 7 when the liquid gas mixture 2 flows through the gas mixture detection module 7.

The gas mixture detection module 7 is thus supplied with a measured value pair of the temperature and the pressure of the gas mixture 2 through the sensors 8, 9. Different saturation vapor pressure curves 20 for different mixing ratios of the gas mixture 2 are stored in the gas mixture detection module 7 and the gas mixture detection module 7 is equipped in hardware and software so that it can determine the current mixing ratio of the gas mixture 2 on the basis of the measured values and the saturation vapor pressure curves 20. How this works is described below with reference to FIGS. 4, 6, 8 and 10.

The calculated mixing ratio of the gas mixture 2 is now transmitted via the electrical lines 14 to the gas control unit 13 analog or digital. In the gas control unit 13 in turn gas maps 21 are stored for different mixing ratios of the gas mixture 2. How the gas maps 21 look and the assignment to the saturation vapor pressure curves 20 expires will be described below.

Depending on the determined current mixing ratio of the gas mixture 2, the appropriate gas map 21 and the values to be used therein are now selected by the gas control device 13. Depending on this, the injection of the gas mixture 2 through the injection valves 11 into the combustion chamber of the engine 19 takes place, so that proper combustion is ensured.

Control in defined time intervals

The gas mixture detection module 7 is preferably designed such that it repeatedly carries out the determination of the current mixing ratio of the gas mixture 2 at defined time intervals. These time intervals are after starting the engine 19, so that the measurements are thus carried out several times while the engine 19 is running. The time interval is freely selectable per se, wherein it has been shown that a time interval of between approximately 20 seconds and 5 minutes, in particular between approximately 20 to 40 seconds and preferably of approximately 30 seconds, is advantageous. Through this repeatedly performed measurement and the corresponding control, there are various advantages, as will be further described below.

Due to the fact that a determination of the mixture ratio of the gas mixture 2 and a dependent regulation of the gas control device 13 is performed at all, it is initially ensured at the beginning of the gas combustion operation - possibly even after a refueling of the gas tank 3 - that a proper gas combustion process is independent of the mixing ratio takes place in the engine 19.

However, the repeated measurements and adjustments during operation also take temperature fluctuations into account, such as the wind, parking the vehicle in the sun, parking the vehicle in a garage, and then operating at minus temperatures, etc. occur. These temperature differences leading to a change in the density of the gas mixture are now taken into account by a corresponding selection of another gas map 21 by the gas control device 13 in the sense of a proper combustion. Another essential advantage is that even the gasoline control unit 16, which is also permanently operated in the gas combustion mode, is not unintentionally displaced, as has already been described in detail above.

FIG. 2 shows a schematized view of a second exemplary embodiment of the new device 1. In this case, in contrast to the embodiment illustrated in FIG. 1, this is not an injection system but an injection system, and more specifically a direct injection injection system. This embodiment has many features consistent with the embodiment of FIG. 1, so that reference is made to the above embodiments to avoid unnecessary repetition.

Since the device 1 not for injection, but for injection - d. H. for introducing the gas mixture 2 in liquid form into the combustion chamber of the engine 19 - is formed, this has no evaporator / pressure regulator 10, but u. a. a fuel delivery pump 22. The fuel delivery pump 22 is connected via the line 6 and a gas inlet 23 to a valve block 24. The valve block 24 is in turn connected via lines 25, 26 with a high-pressure pump 27. From the high-pressure pump 27, a line 28 leads to the gasoline injection valves 18. The gasoline injection valves 18 are used in the gas combustion operation for the injection of the liquid gas, so that they simultaneously form gas injection valves 29. In other words, in addition to the gasoline injection valves 18, no separate injection valves are required for the gas. The valve block 24 furthermore has a gas return 30, via which liquid gas mixture 2 is returned to the gas tank 3. Further recognizable are the gasoline flow 31 and the gasoline return 32, which are also connected to the valve block 24.

In this embodiment of the device 1, the high-pressure pump 27 and the gasoline injection valves 18 are thus used in the gas mode for supplying the liquid gas mixture 2 into the combustion chamber of the engine 19 in a known manner.

In contrast to the embodiment of the device 1 according to FIG. 1, here the sensors 8, 9 are arranged outside the housing of the gas mixture detection module 7. The sensors 8, 9 are connected via electrical lines 35 to the gas mixture detection module 7. 3 shows a further exemplary embodiment of the new device 1. This is an injection system in which the injection into the intake passage of the engine 19 takes place. This embodiment has many features consistent with the embodiments of FIGS. 1 and 2, so that reference is made to avoid unnecessary repetition on the above-mentioned embodiments.

In this case, the fuel delivery pump 22 is connected to the gas injection valves 29 via the gas inlet 23. The pressure required for the injection is established via a pressure regulator 33, which is connected via a line 34 to the gas injection valves 29. The gas return 30 then returns to the gas tank 3. Also in this embodiment of the device 1, the temperature sensor 8 and the pressure sensor 9 are arranged outside of the gas mixture detection module 7 and connected via electrical lines 35 thereto.

Depending on the current mixing ratio of the gas mixture (2), therefore, the gas control unit (13) is controlled to ensure optimum combustion in the gas combustion operation, without the gasoline combustion operation is adversely affected.

FIG. 4 shows a saturation vapor pressure curve 20 for a specific mixing ratio of a specific gas mixture 2. In the present case, the gas mixture 2 is LPG, ie. H. a mixture of propane and butane.

FIG. 4 shows a gas mixture 2 with a proportion of propane of 20% and a proportion of butane of 80% (in each case in volume percent). The further figures 6, 8 and 10 show corresponding saturation vapor pressure curves 20 for other mixing ratios of the gas mixture 2. It is understood that corresponding saturation vapor pressure curves 20 can be given for further mixing ratios and also for gas mixtures 2 consisting of other gases. In the saturation vapor pressure curves 20, the saturation vapor pressure in millibar (mbar) is indicated on the vertical axis. The horizontal axis shows the temperature in degrees Celsius (° C). For example, as shown by a comparison of FIG. 4 with FIG. 10, LPG having a mixing ratio of 20% propane and 80% butane at a temperature of 0 ° C a pressure of slightly less than 2000 mbar (ie 2 bar) on. At a mixing ratio of 85% propane and 15% butane, the pressure at the temperature of 0 ° C is already slightly more than 4000 mbar (ie 4 bar) and thus more than twice. By using a plurality and in particular a plurality of such saturation vapor pressure curves 20, the mixing ratio of the gas mixture 2 can thus be determined on the basis of the respective measured value pair of temperature and pressure.

FIGS. 5, 7, 9 and 11 show the gas maps 21 assigned to the respective mixing ratio. In the gas maps 21, the injection time in milliseconds (ms) and the speed of the motor 19 in revolutions per minute (rpm) is given. For example, the injection time of 3.00 ms at a speed of 4000 rpm is assigned the numerical value "1 1". This numerical value "1 1" represents the injection quantity and represents the amount of gas that is selectively supplied to the individual engine combustion chambers.

According to the invention, in each case the appropriate gas map 21 is selected in the gas control device 13 as a function of the determined mixture ratio of the gas mixture 2, thereby controlling the injection or injection of the gas mixture 2 to achieve optimal combustion.

The "saturation vapor pressure curves" according to the invention describe the mutual dependence of the vapor pressure, the temperature and the mixing ratio propane / butane. For the explanation of the invention, cf. also FIGS. 4, 6, 8, 10 with associated description, different saturation vapor curves with the vapor pressure over the temperature for different mixing ratios have been specified and taken into account in the gas mixture detection module. It is understood that the saturation vapor pressure curves can also be stored for different temperatures with the vapor pressure above the mixing ratio and / or for different vapor pressures with the mixing ratio above the temperature and taken into account in the gas mixture detection module.

Also a consideration of the saturation vapor curves in the form of a multi-dimensional characteristic map,

a derived from physics functional dependence or approximating functional dependencies of, for example, measured saturation vapor behavior

imitate the invention possible.

REFERENCE LIST Device

mixture of gases

gas tank

Multiventil

swimmer

management

Gas mixture recognition module

temperature sensor

pressure sensor

Evaporator / pressure regulator

gas injection

Electrical line

Gas control device

Electrical line

Gasoline controller

Electrical line

Fuel injectors

engine

Saturation vapor pressure curve

Gas map

Fuel pump

gas supply

manifold

management

high pressure pump

management

Gas injection valve

Gas return

gasoline supply

Gasoline return

pressure regulator

management

Electrical line

Claims

1 . Gas mixture detection module (7) for determining the mixing ratio of a liquid gas mixture (2) of a first liquid gas and a second liquid gas, wherein the gas mixture (2) is liquefied petroleum gas (LPG) and propane and butane, wherein the gas mixture (2) for the Combustion in an engine (19) of a motor vehicle with a gasoline control unit (16) and a gas control unit (13) and is supplied to the engine (19) from a gas tank (3) of the motor vehicle,

wherein the mixed gas detection module (7) is designed to receive a value of the pressure of the gas mixture (2) in the gas tank (3) and the temperature of the liquid gas mixture (2) and can be connected to the gas control unit (13) via electrical lines (14), and

wherein the mixed gas detection module (7) for determining the actual mixing ratio of the gas mixture (2) by determining the proportions of propane and butane after starting the engine (19) with the engine (19) running by comparing the measured values of the temperature and Pressure of the gas mixture (2) with the corresponding values in saturation vapor pressure curves (20) for different mixing ratios of the gas mixture (2) is formed and wherein the gas control unit (13) the gas injection or gas injection times of the motor (19) in dependence the current mixing ratio of the gas mixture (2) so sets and controls that the gasoline control unit (16) is not adjusted.

2. gas mixture detection module (7) according to claim 1, characterized in that the Gasgemischerkennungsmod ul (7) is designed so that it d the determination of the current mixing ratio of the gas mixture (2) repeatedly carried out at defined time intervals.

3. gas mixture detection module (7) according to claim 2, characterized in that the time interval between 5 seconds and 5 minutes.

4. Device (1) for determining the mixing ratio of a liquid gas mixture (2) of a first liquid gas and a second liquid gas, wherein the Gas mixture (2) LPG is and propane and butane, wherein the gas mixture (2) for combustion in an engine (19) of a motor vehicle with a gasoline control unit (16) and a gas control unit (13) is determined and this from a Gas tank (3) of the motor vehicle is supplied, with

a temperature sensor (8) for measuring the temperature of the liquid gas mixture (2),

a pressure sensor (9) for measuring the pressure of the gas mixture (2) in the gas tank (3), and

a gas mixture detection module (7) according to at least one of claims 1 to 3 connected to the temperature sensor (8) and the pressure sensor (9).

5. A method for controlling a with a liquid gas mixture (2) operated motor (19) of a motor vehicle with a gasoline control unit (16) and a gas control unit (13), wherein the liquid gas mixture (2) comprises a first liquid gas and a second liquid gas wherein the gas mixture (2) is liquefied petroleum gas (LPG) and comprises propane and butane with the steps

Measuring the temperature of the liquid gas mixture (2) with a temperature sensor (8),

Measuring the pressure of the gas mixture (2) located in a gas tank (3) of the motor vehicle with a pressure sensor (9),

Transferring the measured values of the temperature and the pressure of the gas mixture (2) to a gas mixture detection module (7),

repeatedly determining the mixing ratio of the gas mixture (2) with the gas mixture detection module (7) after starting the engine (19) while the engine is running (19) in the sense of determining the proportions of propane and butane by comparing the measured values of temperature and Pressure of the gas mixture (2) with the corresponding values in saturation vapor pressure curves (20) for different mixing ratios of the gas mixture (2), and

Controlling the gas control unit (13) to adapt to the current mixing ratio of the gas mixture (2), wherein the gas control unit (13) comprises a Gasennblas- or Gaseinspritzzeiten containing gas map (21), the Gaseinblas- or gas injection times depending on the current mixing ratio of the gas mixture (2) are adjusted so that the gasoline control unit (16) is not adjusted.

6. The method according to claim 5, characterized in that the determination of the current mixing ratio of the gas mixture (2) is carried out repeatedly in defined time intervals.

7. The method according to claim 6, characterized in that the time interval is between 5 seconds and 5 minutes.

8. The method according to at least one of the preceding claims, characterized in that the liquid gas mixture (2) is evaporated and injected as gas into the motor (19).

9. The method according to at least one of the preceding claims, characterized in that the gas mixture (2) is injected in liquid form into the motor (19).