WO2009015894A1

WO2009015894A1 - Metering system for additives of gas-operated internal combustion engines and method for the metered supply of an additive into a gas tank

Info

Publication number: WO2009015894A1
Application number: PCT/EP2008/006329
Authority: WO
Inventors: Friedrich A. SPRÜGEL; Manfred Köppel
Original assignee: Tunap Industrie Chemie Gmbh & Co. Produktions Kg
Priority date: 2007-08-02
Filing date: 2008-07-31
Publication date: 2009-02-05
Also published as: EP2185803A1; DE102007036217A1

Abstract

The invention relates to a metering system for additives of gas-operated internal combustion engines and to a method for the metered supply of an additive into a gas tank of a gas-operated internal combustion engine. In order to ensure that the concentration of the additive in the gas is constant during the entire gas operation, particularly in the liquid gas, the additive metering system comprises a metering pump (10), wherein the pressure side thereof can be connected to a gas tank (12) of an internal combustion engine via a pressure line (11), a connection device (18) for an additive container (15), with which the additive container (15) can be connected to the intake side of the metering pump (10) via a line arrangement (13), and a control device (16) for controlling the metering pump (10) as a function of a fill level signal (F), which can be fed to the control device (16) from a tank fill level sensor (17) on the gas tank (12). The metering is then executed with the following steps: Determining a gas amount, particularly liquid gas amount, fed to the gas tank (12) during filling; calculating the amount of additive necessary for the filled gas amount, particularly liquid gas amount, based on a set metering amount, and adding of the calculated additive amount into the gas tank (12), wherein the additive is injected under pressure into the gas tank (12) by means of a metering pump (10).

Description

Additive dosing system for gas-powered internal combustion engines as well

Method for the metered feeding of an additive into a gas tank

description

The invention relates to an additive metering system for gas-fueled internal combustion engines and a method for the metered feeding of an additive in a gas tank of a gas-fueled internal combustion engine.

In view of the increasingly stringent exhaust standards for internal combustion engines, in particular for internal combustion engines, which are used in motor vehicles, and with regard to the reduction of environmentally harmful gases, such as nitrogen oxides, CO ₂ and unburned hydrocarbons, more and more users of motor vehicles, which with herkömmli - Chen internal combustion engines are equipped, in addition, at least temporarily operate these engines with gas, in particular LPG. Here, the reduction of pollutant emissions from nitrogen oxides is about 20%, while the emissions of CO ₂ can be reduced by 15% and the unburned hydrocarbons to almost 50%. Due to the virtually complete combustion of LPG exhaust gases, these have better chemical usability and can be reacted at lower temperatures in corresponding catalysts.

The virtually complete combustion of liquefied petroleum gas, in addition to the positive effects on the environment, also has problematic consequences for engine operation. While components of the fuel for internal lubrication, in particular in the region of the valve seats, namely the inlet valves, are used during normal operation of the internal combustion engine with conventional fuels, such components are missing during gas operation. As a result, conventional LPG-powered internal combustion engines must be regularly and often switched to conventional fuels such as gasoline to avoid such difficulties.

Additives or additives for LPG fuels are known. From DE 39 24 596 C l, for example, an additive is known, the corrosion protection, the prevention of deposits on engine parts and the Purification of exhaust gases used by LPG-powered internal combustion engines.

From DE 33 37 983 Al a method, a device and means for continuously supplying gasoline-powered internal combustion engines and / or auxiliary equipment thereof with additives or additives are already known in which an additive or additive to be added to the gasoline is continuously added to a line, in the excess liquid fuel of the internal combustion engine and / or the hip device is returned to a storage tank. However, with such a known device can be in an internal combustion engine, which can be operated with either conventional liquid fuel and LPG, do not achieve accurate metering of an additive to the LPG, which is required on the one hand to ensure the lubrication of the valve seats and on the other hand with the Gas operation achieved benefits to the environment not to destroy.

Based on this, the object of the invention is to provide an additive metering system for gas-operated internal combustion engines and a corresponding metering method with which it is possible to ensure that the additive concentration in the gas, in particular in the LPG, is constant throughout the gas operation.

This object is achieved by the additive metering system according to patent claim 1 and by the method according to claim 13. Advantageous embodiments and further developments of the invention are described in the respective subclaims.

According to the present invention, therefore, an additive metering system for gas-fueled internal combustion engines has a metering pump whose pressure side can be connected via a pressure line to a gas tank of an internal combustion engine, a connecting device for an additive container, with which the additive container can be connected via a line arrangement to the suction side of the metering pump, and a control device which controls the metering pump in response to a level signal that can be fed to the control device from a tank level sensor on the gas tank. According to the invention, therefore, the metered supply of an additive takes place directly into the gas tank of an internal combustion engine, the adjustment of the amount of additive to be supplied depending on the level of the tank, in particular in response to a positive level change occurs, as occurs every refueling of the gas tank. The automatic accurate metering of the additive for the gas, in particular for the LPG in the gas tank has the advantage that the correct additive concentration is maintained constant in the LPG without the user of the engine, so for example the driver of a motor vehicle operated therewith, any additional Must take action.

In order to achieve a particularly accurate and reliable supply of a desired amount of additive, it is provided that the metering pump is a suction and pressure pump, which delivers the additive for metering under high pressure intermittently in the gas tank during operation, the metering pump in operation, the additive with a pressure in the gas tank that is greater than the internal pressure of the gas tank, preferably greater than 10 bar, in particular about 15 bar.

The use of a supply or injection pressure for the additive, which is significantly higher than the internal pressure of the gas container, has the result that the additive supplied quickly and evenly distributed in the gas tank and mixed with the liquid gas therein.

In order to simplify the maintenance of the additive metering system and in particular the replacement of additive containers, it is provided that the connection device for the additive container, a receiving device for holding the additive container and an adapter for connecting a connection piece of the additive container with the leading to the suction side of the metering pump line arrangement having.

Advantageously, it is provided that the adapter has a receiving opening for the connection piece of the additive container and a surrounding the receiving opening seal, which cooperates with a surrounding the fitting sealing surface on the additive container when an additive container is inserted with its connection piece in the receiving opening to the additive container pressure-tight with the suction side of the Dosing pump leading line assembly to connect, wherein a hollow pin for opening an outlet valve in the connection piece of the additive container centrally projects into the receiving opening for the connection piece.

To further simplify the handling of the additive metering system according to the invention is further provided that the receiving device for pressure and gas-tight fixing of the connection piece of an additive container in the adapter has locking means through which the additive container can be pressed against the adapter.

A particularly advantageous embodiment of the invention is characterized in that the control device or control device has a monitoring circuit for detecting a refueling operation, which compares a current level signal with a stored level signal and detects a refueling operation when the current level signal indicates a higher tank level than the stored.

The recognition of a refueling process on the basis of a positively changing filling level has the advantage that the control device requires only a single external signal for the reliable operation of the metering system, which considerably facilitates the installation, in particular the subsequent installation, for example in a vehicle.

However, it is also possible that the control device can be supplied with a tank signal from a sensor switch arranged at a gas filling connection of the gas tank, and the control device has a monitoring circuit for detecting a refueling process which monitors the tank signal.

The use of an additional tank signal to detect a refueling process makes the control of the dosing system particularly easy.

In an advantageous embodiment of the invention it is provided that the

Control device, a computing circuit for determining the amount of additive to be supplied to the gas tank from a current and a stored

Level signal and has a control signal generator, depending on supplied by the determined amount of additive generated control signals to the metering pump.

In order to further increase the reliability of the additive metering system according to the invention and to simplify its handling, it is provided that the control device has a monitoring circuit for detecting the

Has filling level of the additive container, which calculates the level of the supplied to the gas tank additive amounts, and the container controls a warning and / or level indicator according to the level of Zusatzstoffbe- container.

Although it is conceivable in principle to reset the monitoring circuit for detecting the filling level of the additive container, for example via a provided in the receiving device switch, which is actuated by the additive container, according to the invention provided that a manually operable reset switch is attached to the control device, so that the Monitoring circuit for detecting the level of the additive container when changing it is manually reset. The manual reset of the monitoring circuit has the advantage that it is not automatically reset every time you remove and install an additive container, but only if after replacing an empty additive container against a full reset switch is operated.

The dosed feeding of an additive into a gas tank of a gas-operated internal combustion engine expediently takes place in the following manner: determination of a quantity of gas supplied to the gas tank during a refueling process, in particular amount of liquid gas, calculation of the amount of additive required for the refueled liquid gas quantity based on a set metering quantity, and feeding of the calculated amount of additive the gas tank, wherein the additive is injected by means of a metering pump under pressure into the gas tank.

The additive is injected intermittently into the gas tank by the metering pump, the number of injections being determined from the calculated amount of additive and the delivery quantity per injection stroke. Conveniently, to detect a refueling operation, a current fill level signal is compared with a stored fill level signal, and a refueling operation is detected when the current fill level signal indicates a higher refueling level than the stored one.

However, it is also possible that, for detecting a refueling operation, a tank signal monitored by a sensor switch disposed at a gas filling port of the gas tank is monitored.

The invention will be explained in more detail below, for example, with reference to the drawing. Show it:

Figure 1 is a schematic representation of an additive metering system;

FIG. 2 shows a connecting device for an additional container;

Figure 3 is an enlarged, partially sectioned schematic representation of an adapter of the connection device and a connecting piece of an additional container to be connected thereto;

Figure 4 is a simplified schematic block diagram of a first embodiment of a control device for the additive metering system; and

FIG. 5 shows a simplified schematic block diagram of a further embodiment of the control device of the additive dosing system according to the invention.

In the various figures of the drawing corresponding components and circuit elements are provided with the same reference numerals.

As shown in FIG. 1, the additive dosing system according to the invention for gas-fueled internal combustion engines has a dosing pump 10 whose output-side pressure side is connected via a pressure line 11 to a gas tank 12 of an internal combustion engine, not shown, via a gas line 12 '. The connection to the gas tank 12 takes place via a high-pressure connection 12 ", in which a check valve is integrated. The pump side of the metering pump 10, so the suction side is connected via a connecting line 13 and an adapter 14 with an additive container 15.

The metering pump 10, which is designed as a suction and pressure pump, is controlled by a control device 16 to accurately metered into the additive container 15 additive or additive in the gas tank 12 and so the additive concentration in the gas tank 12 located in the LPG exactly on the Set value that is required for the desired lubricating effect during operation of the internal combustion engine.

The metering pump 10 is designed so that it provides the additive with a pressure intermittently in the gas tank 12, which is greater than the internal pressure of the gas tank 12. Conventional gas tanks, such as those used for internal combustion engines in motor vehicles, have an internal pressure of about 5 to 8 bar at temperatures in the range of 20 to 30 ⁰ C, which ensures that the gas in the gas tank, usually way a mixture of propane and butane, in the liquid phase.

As explained in more detail below, the amount of additive to be introduced into the gas tank 12 is determined by the control device 16 during each refueling process for the replenished amount of liquefied gas, which then delivers a corresponding control signal Sp to the metering pump 10. In order to be able to determine the amount of gasified gas, the control device 16 detects a filling level signal F, which is supplied by a tank level sensor 17 in the gas tank 12. The level signal F may be a voltage supplied by a potentiometer, which must be converted via a corresponding calibration function for the gas tank 12 in a level, but also a signal that indicates the level directly or this directly corresponds.

The connection line 13, which is shown schematically in FIG. 1 as a continuous line, can also comprise suitable angle pieces and further connection elements, depending on the respective installation conditions in a corresponding housing.

For the pressure line 11, which leads from the pressure side of the metering pump to the gas tank 12, pressure lines and pressure line connections are preferably provided. used fertilize, as used for example for pressure lines in brake systems of motor vehicles. This high gas-tightness can be achieved, which corresponds to the safety regulations for the use of LPG in motor vehicles.

In order to be able to simply replace an empty additive container 15 with a full additive container 15, a connecting device 18 has a receiving device 19 for the additive container 15 and the adapter 14. The receiving device 19, which is shown schematically as a u-shaped frame 19 'in FIG. 2, delimits a receiving area 20 for the additive container 15 and supports the adapter 14 and fixing means 21, with the aid of which the additive container 15 in the receiving area 20 of the receiving device 19 can be fixed so that a connector 22 (see Figure 3) of the additive container 15 pressure and gas tight against the adapter 14 can be kept pressed.

As shown in FIG. 3, the connecting piece 22 is surrounded by an annular trench 23, the inwardly facing circumferential surface 24 of which is designed as a sealing surface which cooperates with a seal 25, for example formed as an O-ring, on the adapter 14 when the connecting piece 22 is received in a receptacle 26 provided for this purpose in the adapter 14, while at the same time a receiving opening 26 surrounding ring portion 27 of the adapter 14 is immersed in the trench 23.

When the connecting portion of the additive container 15 is connected to the adapter 14, at the same time a hollow pin 28 presses an only schematically indicated outlet valve 29 of the additive container 15, so that the additive or additive from the additive container 15 through the hollow pin 28 and adjacent axial passages 30 and an outlet bore 30 'can flow to the connection line 13, which is connected depending on the installation conditions with a union nut 31 - as shown in Figure 3 - or an unillustrated angle piece with a connecting piece 32 of the adapter 14.

In order to replace one arranged in the receiving device 19 and fixed additive container 15 against another, first a support member 33 of the locking means 21, which is shown as a support plate, 2 by appropriate adjusting means 34, which are indicated here as screws, moved from the position shown in Figure 2 to the left, so that the additive container 15 can be withdrawn with its connection portion of the adapter 14 and removed from the receiving area 20 of the receiving device 19.

Subsequently, a full additive container 15 is inserted into the receiving area 20 and pushed with its connection area against the adapter 14 so that the annular portion 27 of the adapter 14 in the trench 23 and the connector 22 of the additive container 15 is immersed in the receiving opening 26 of the adapter 14. Thereafter, the support member 33 is moved against the bottom of the additive container 15 until it rests against it and now pushes the additive container 15 further in the direction of the adapter 14 until the seal 25 comes into sealing engagement with the peripheral surface 24 of the trench 23 and the hollow pin 28th the outlet valve 29 of the additive container 15 has opened so that additive from the additive container 15 can flow to the metering pump 10 via the line arrangement connected to the adapter 14, which is schematically indicated in the drawing as a connecting line 13.

The adjusting means 34 are designed so that they also keep the additive container 15 safely in pressure and gas-tight engagement with the adapter 14 when the receiving device 19 is exposed in continuous operation in a motor vehicle constantly changing vibrations.

In order to deliver an additive from the additive container 15 into the gas tank 12, the dosing pump 10 activated via the control signal S _p sucks additive from the additive container 15 and conveys it at high pressure, for example at 15 bar via the pressure line 1 1 intermittently into the gas tank 12. The amount of pump delivery per pump cycle or impulse is, for example, 0.02 ml and essentially determines the metering accuracy according to size and constancy. If a higher dosing accuracy is required, then a metering pump with a smaller delivery volume per pump cycle or pump surge must be selected, which is kept constant with high accuracy even in long-term operation, while conversely, a larger delivery volume per pumping cycle can be selected if the smallest Dosiermenge may be greater. If a certain amount of M _T additive is to be pumped into the gas tank, so The number N of pump cycles or pulses that the metering pump 10 has to perform results from the quotient of additive quantity M _T to be supplied to the gas tank 12 divided by the delivery volume Mp per pump cycle.

In order to allow a complete emptying of the additive container 15, this is advantageously formed by a two-chamber container, one chamber is a flexible plastic or aluminum bag containing the additive, while the other chamber from the space between the plastic or aluminum bag and the outer wall the container is formed. The second chamber is expediently under ambient pressure and has a pressure equalization opening in the bottom so that ambient air can flow freely into the second chamber.

As shown in FIG. 4, the control device 16 has a monitoring circuit 41 to which the fill level signal F from the tank level sensor 17 at the gas tank 12 is supplied. The monitoring _circuit 41 compares the current level signal F _act with a stored level _signal F _mln and stores the current level _signal F _alςt as a level _signal F _m m, if the current level _signal F _{act is} smaller than the previously stored level signal F _m i _n , in a memory 42nd If the current fill level signal F _{akt is} greater than the stored fill level signal F _min , which is the case, for example, during or at least after a refueling operation, then the current fill level _signal F _{alct is} stored in memory 42 as F _max . As long as the current level signal rises during the refueling process, the monitoring circuit overwrites the stored level signal F _max continuously until the refueling signal stops increasing at the end of refueling. Hereupon, the monitoring _{circuit 41 recognizes} that the refueling process has ended and then activates a _{calculation circuit 43} which multiplies the amount of additive M _T to be supplied to the gas tank from the difference between the level F _101n before refueling and the level F _max after refueling with the desired level Additive concentration K _a in the gas used as fuel, in particular LPG. The computing circuit 42 supplies the calculated additive amount M _T to a control signal generator 44 and to a monitoring circuit 45, which monitors the filling state of the auxiliary container 15 in order to deliver a corresponding warning signal Sw in good time before the complete emptying of the auxiliary container 15. The control signal generator 44 determines from the amount of additive MT to be supplied to the gas tank 12 the number of pump cycles or pump surges to be executed by the metering pump 10 and controls them accordingly.

The monitoring circuit 45 calculates the filling state of the additive container 15 as a difference between the filling state MB before refueling and the additive amount M _T supplied to the gas tank 12 and compares the filling amount M _B after refueling with a limit value Mg and outputs a warning signal Sw indicating that the additive in the additive container will soon be used up. Here, it is also conceivable that the current filling state M _{B of} the additive container 15 is not only stored, but can also be displayed by means of a suitable analog or digital display, as shown in Figure 4 by the dashed arrow line and the number on a display device 49 of a user interface 47 is indicated.

In order to reset the filling state value M _B for the additive container 15 to its original value after a change of the additive container 15, a manually operable reset switch 46 is expediently provided, which is actuated after the replacement of an additive container 15. The reset switch 46 is part of the user interface 47, which can have as further input means, for example, a four-way joystick 47 ', a keypad 47 ", a so-called touch panel or the like 49 for displaying corresponding output data of the control device 16.

As FIG. 5 shows, a control device 16 'according to another embodiment of the invention for detecting a refueling operation has a monitoring circuit 51 to which a tank signal S _t indicative of a refueling process is supplied. The tank signal S _t can be supplied, for example, from a sensor switch 17 'to the control device 16', which is provided at a gas filling connection 12 '"on the gas tank 12, as indicated by dashed lines in FIG.

Shows the tank signal S _t that a refueling operation is initiated, causes the monitoring circuit 51 that the current fill level signal F is indicative of a minimum signal level _Fmin in the memory 42 is stored. To Completion of the refueling process, which is also indicated by the tank signal St, then the now existing level signal F is taken as the maximum level signal F _max for the determination of the gas tank 12 to be supplied additive amount M _T in the memory 42. After completion of the refueling operation, the corresponding additive quantity M _T can be calculated from a start signal from the monitoring circuit 51, as described above, from the calculation circuit 43 from the fill levels before and after refueling the gas tank 12 taking into account the desired additive concentration K ₃ . The control of the metering pump 10 and the monitoring of Füllzu- state of the additive container 15 is then carried out in the same manner as described above.

The additive dosing system according to the invention is particularly suitable for retrofitting motor vehicles which can operate conventional internal combustion engines both with conventional liquid fuels, such as gasoline, and with gas, in particular liquefied petroleum gas. For this purpose, the metering system is expediently arranged in a suitable housing, so that it can be arranged in the trunk of a motor vehicle or at another suitable location near the gas tank. For the installation of the additive metering system according to the invention in a motor vehicle, either together with a liquefied gas system or subsequently, it is particularly appropriate that only an external signal is required in addition to the power supply to ensure a reliable supply of always accurately measured amounts of additive in the gas tank.

In the event that it is necessary to adjust the concentration of the additive therein differently because of a changed composition of the fuel gas, the corresponding concentration value K ₃ can be changed via the user interface 47. This can be done, for example, by directly inputting a corresponding additive concentration value for a particular fuel gas composition, or by storing the corresponding concentration values for the various fuel gas compositions in the memory 42 so that only the corresponding gas or liquid gas mixture is reported needs. With the aid of the additive dosing system according to the invention can thus ensure that a conventional engine is reliably protected against damage during operation with gas, without the user would have to provide for each fueling cumbersome way for an additive supply to the gas tanked.

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Claims

claims

1. additive metering system for gas-fueled internal combustion engines, with a metering pump (10) whose pressure side via a pressure line (1 1) with a gas tank (12) of an internal combustion engine is connectable, a connection device (18) for an additive container (15), with the the additive container (15) can be connected via a line arrangement (13) to the suction side of the metering pump (10), and a control device (16) for controlling the metering pump (10) as a function of a fill level signal (F) which is present in the control device (15). 16) from a tank level sensor (17) on the gas tank (12) can be supplied.

2. additive metering system according to claim 1, characterized in that the metering pump (10) is a suction and pressure pump, which provides the additive for metering under high pressure intermittently in the gas tank (12) during operation.

3. additive metering system according to claim 2, characterized in that the metering pump (10) in operation delivers the additive with a pressure in the gas tank (12) which is greater than the internal pressure of the gas tank (12), preferably greater than 10 bar, in particular is about 15 bar.

4. additive dosing system according to claim 1, 2 or 3, characterized in that the connection device (18) for the additive container (15) - a receiving device (19) for holding the additive container (15) and an adapter (14) for connecting a connector (22) of the additive container (15) with the leading to the suction side of the metering pump (10) line arrangement (13).

5. additive metering system according to claim 4, characterized in that the adapter (14) has a receiving opening (26) for the connecting piece (22) of the additive container (15) and a receiving opening (26) surrounding the seal with a connecting piece (26). 22) surrounding the sealing surface on the additive container (15) cooperates when a Zusatzstoffbe- container (15) with its connecting piece (22) into the receiving opening (26) is used to connect the additive container (15) pressure-tight with the leading to the suction side of the metering pump (10) line arrangement.

6. additive metering system according to claim 5, characterized in that a hollow pin (28) for opening an outlet valve (29) in the connecting piece

(22) of the additive container (15) projects centrally into the receiving opening (26) for the connecting piece (22).

7. additive metering system according to claim 4, 5 or 6 characterized in that the receiving device (19) for pressure and gas-tight fixing of the connecting piece (22) of an additive container (15) in the adapter (14) has locking means by the Additive container (15) against the adapter (14) can be pressed.

8. additive metering system according to any one of the preceding claims, characterized in that the control device (16) has a monitoring circuit for detecting a refueling operation, which compares a current level signal with a stored level signal and detects a refueling, when the current level signal a higher tank level indicates as the stored.

9. additive dosing system according to one of claims 1 to 7, characterized in that the control device (16) a tank signal from a filling line of the gas tank arranged on the sensor switch can be fed, and the control device (16) has a monitoring circuit for detecting a refueling operation has, which monitors the tank signal.

10. additive metering system according to one of the preceding claims, character- ized in that the control device (16) has a computing circuit (43) for determining the amount of additive to be supplied to the gas tank (12) from a current and a stored level signal and a control signal generator ( 44) which supplies control signals generated in dependence on the determined amount of additive to the metering pump (10).

1 1. additive dosing system according to one of the preceding claims, characterized in that the control device (16) has a monitoring circle (45) for detecting the level of the additive container (15), which calculates the level of the supplied to the gas tank (12) additive amounts, and controls a warning and / or level indicator according to the level of the additive container.

12. additive metering system according to claim 5, characterized in that on the control device (16) a manually operable reset switch is provided so that the monitoring circuit (45) for detecting the level of the additive container (15) when changing the same is reset.

13. A method for the metered feeding of an additive in a gas tank of a gas-fueled internal combustion engine, comprising the following steps:

Determining a quantity of gas supplied to the gas tank (12) during a refueling operation, in particular the amount of liquid gas,

Calculating the required amount of gas for the amount of gas, in particular liquid amount of additive on the basis of a set dosage, and

Feeding the calculated amount of additive in the gas tank (12), wherein the additive is injected by means of a metering pump (10) under pressure in the gas tank (12).

14. The method according to claim 13, characterized in that the additive from the metering pump (10) intermittently into the gas tank (12) is injected.

15. The method according to claim 14, characterized in that the number of injections is determined from the calculated amount of additive and the flow rate per injection stroke.

16. The method of claim 13, 14 or 15, characterized in that for detecting a refueling operation, a current level signal is compared with a stored level signal and that a refueling operation is detected when the current level signal indicates a higher tank level than the stored.

17. The method of claim 13, 14 or 15, characterized in that for detecting a refueling operation, a tank signal is monitored, which is supplied by a arranged at a Gaseinfüllanschluss the gas tank sensor switch.