DE102007036217A1 - Additive dosing system for gas-fueled internal combustion engines and method for the metered feeding of an additive in a gas tank - Google Patents

Abstract

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. To ensure that the additive concentration in the gas, in particular in the LPG, is constant throughout the gas operation, the additive metering system comprises a metering pump (10) whose pressure side can be connected via a pressure line (11) to a gas tank (12) of an internal combustion engine, a connection device (18) for an additive container (15), with which 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) Dependence on a level signal (F) which can be fed to the control device (16) from a tank level sensor (17) on the gas tank (12). The metering is then carried out with the following steps: determining a gas quantity supplied to the gas tank (12) during a refueling operation, in particular amount of liquefied gas, calculating the amount of additive required for the gas quantity, in particular amount of liquefied gas, based on a set metering amount and feeding the calculated amount of additive into the tank Gas tank (12), wherein the additive is injected by means of a metering pump (10) under pressure in the gas tank (12).

Description

The The invention relates to an additive metering system for gas powered Internal combustion engines and a method for metered feeding an additive in a gas tank of a gas-fired 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 polluting gases, such as nitrogen oxides, CO ₂ and unburned hydrocarbons, more and more users of motor vehicles, with conventional Are equipped with internal combustion engines, over to operate these engines, at least temporarily, 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 a better chemical recovery and can be implemented at lower temperatures in corresponding catalysts.

The virtually complete combustion of LPG but has a positive impact on the environment as well as problematic ones Consequences for the engine operation. While in the Normal operation of the internal combustion engine with conventional fuels Components of the fuel for internal lubrication, in particular used in the area of the valve seats, namely the intake valves are missing, such components in gas operation. this has As a result, conventional internal combustion engines with LPG operated regularly and often on the operation with conventional Fuels, such as gasoline, need to be switched to to avoid such difficulties.

Additives or additives for LPG fuels are known. From the DE 39 24 596 C1 For example, an additive is known which serves for corrosion protection, the prevention of deposits on engine parts and the cleanliness of exhaust gases from LPG-powered internal combustion engines.

From the DE 33 37 983 A1 are already a method, an apparatus and means for continuously supplying gasoline-powered internal combustion engines and / or auxiliary equipment thereof with additives or additives 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 auxiliary 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.

From that Based on the object of the invention, an additive metering system for gas-powered internal combustion engines and a corresponding To provide a metering process that can be used to ensure that during the entire gas operation, the additive concentration in the gas, in particular in the liquefied gas is constant.

These Task is by the additive metering system according to claim 1 and solved by the method according to claim 13. advantageous Embodiments and developments of the invention are in the respective Subclaims described.

According to the The present invention thus has an additive dosing system for gas-powered internal combustion engines a metering pump whose pressure side over a pressure line with a gas tank of an internal combustion engine connected is, a connection device for an additive container, with the additive container via a conduit arrangement can be connected to the suction side of the metering pump, and a control device which the dosing pump in dependence controlled by a level signal, that of the control device from a tank level sensor to the gas tank fed is.

According to the invention So the metered supply of an additive directly in the gas tank of an internal combustion engine, the setting of the amount of additive to be supplied depending on the level of the tank, in particular depending from a positive level change, as it occurs when refueling the gas tank. The automatic exact dosage of the additive for the gas, in particular for the liquefied gas in the gas tank has the advantage that the correct additive concentration in the liquefied gas is maintained constantly, without the user of the internal combustion engine, So for example, the driver of a motor vehicle operated with it, take any additional measures got to.

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 pushes the additive for metering under high pressure during operation delivers in the gas tank, wherein the metering pump delivers the additive in operation with a pressure in the gas tank, which 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 tank, has the consequence that the supplied Additive quickly and evenly in the gas tank distributed and mixed with the liquid gas therein.

Around the maintenance of the additive dosing system and in particular the replacement of additive containers is proposed, that the connection device for the additive container a Receiving device for holding the additive container and an adapter for connecting a fitting of the Additive container with the suction side of the metering pump has leading line arrangement.

advantageously, is provided that the adapter has a receiving opening for the connection piece of the additive container and has a seal surrounding the receiving opening, the with a surrounding the fitting sealing surface cooperates with the additive container, if an additive container with its connection piece in the receiving opening is used to the additive container with pressure-tight the leading to the suction side of the dosing pump line arrangement to connect, with a hollow pin for opening an exhaust valve in the connection piece of the additive container centrally into the receiving opening for the connection piece protrudes into it.

To further simplification of the handling of the invention Additive metering system is further provided that the receiving device for Pressure- and gas-tight fixing of the connection piece of a Additive container in the adapter has locking means, by the additive container against the adapter printable is.

A particularly advantageous embodiment of the invention is characterized characterized in that the control device or control device a monitoring circuit for recording a refueling process having a current level signal with a stored Level signal compares and detects a refueling process, if the current level signal is higher Tank level indicates as the stored.

The Recognition of a refueling process based on a positive change Level has the advantage that the control device only a single external signal for the reliable Operation of the dosing required what the installation, especially the subsequent installation, for example in a vehicle essential facilitated.

It However, it is also possible that the control device a Tank signal from one at a Gaseinfüllanschluss the gas tank arranged sensor switch can be supplied, and the control device has a monitoring circuit for detecting a refueling operation that monitors the tank signal.

By the use of an additional tank signal for detection During refueling, the dosing system can be controlled make it really easy.

at an advantageous embodiment of the invention is provided that the control device has a computing circuit for determining the the amount of additive to be supplied to the gas tank from a current and a stored level signal and a control signal generator which, depending on the determined amount of additive generates generated control signals to the metering pump.

Around the reliability of the invention Additive dosing continue to increase and their handling to simplify, it is provided that the control device has a monitoring circuit for detecting the level of the additive container has, the level of which supplied to the gas tank Amounts of additive calculated, and a warning and / or level indicator according to the level of the additive container controls.

Even though it is fundamentally conceivable the surveillance circuit for detecting the level of the additive container for example, via a provided in the receiving device Switch operating from the additive tank is reset, it is provided according to the invention that on the control device, a manually operated reset switch is appropriate, so that the monitoring circuit for detection the level of the additive container when changing it is manually resettable. The manual reset The monitoring circuit has the advantage that it is not with each removal and installation of an additive container automatically is reset, but only if after the exchange of an empty additive container against a full one of the reset switch is pressed.

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

Of the Additive is thereby intermittently from the metering pump injected the gas tank, taking the calculated amount of additive and the flow rate per injection stroke the number the injections is determined.

Conveniently, For detecting a refueling process, a current fill level signal is output compared with a stored level signal and a Refueling detected when the current level signal indicates a higher tank level than the stored one.

It However, it is also possible to record a refueling process a tank signal is monitored, the one from a gas filling port of the Gas tanks arranged sensor switch is delivered.

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

1 a schematic representation of an additive metering system;

2 a connection device for an additional container;

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

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

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

In The various figures of the drawing are corresponding to each other Components and circuit elements provided with the same reference numerals.

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

The dosing pump 10 , which is designed as a suction and pressure pump is controlled by a control device 16 controlled to one in the additive container 15 additive or additive accurately measured in the gas tank 12 one and thus the additive concentration in the gas tank 12 accurately adjusted to the value required for the desired lubricating effect during operation of the internal combustion engine.

The dosing pump 10 It is designed so that the additive with a pressure intermittently into the gas tank 12 which is greater than the internal pressure of the gas tank 12 is. Usual 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 ° C, which ensures that the gas in the gas tank, usually a mixture from propane and butane, in the liquid phase.

As will be explained in more detail below, the amount of additive that enters the gas tank 12 is to be initiated at each refueling process for the refueled amount of liquefied gas from the control device 16 determined, then a corresponding control signal S _p to the metering pump 10 supplies. In order to be able to determine the amount of gasified gas, the control device detects 16 a level signal F from a tank level sensor 17 in the gas tank 12 is delivered. The level signal F may be a voltage supplied by a potentiometer via a corresponding calibration function for the gas tank 12 must be implemented in a level, but also a signal that indicates the level directly or this corresponds directly.

The connection cable 13 , in the 1 is shown schematically as a continuous line may, depending on the particular installation conditions in a corresponding housing, also include suitable angle pieces and other connection elements.

For the pressure line 11 , which from the pressure side of the metering pump to the gas tank 12 leads, preferably pressure lines and pressure line connections are used, as used for example for pressure lines in brake systems of motor vehicles. This can be a high gas that meets the safety requirements for the use of liquefied petroleum gas in motor vehicles.

To an empty additive container 15 simply against a full additive container 15 to be able to exchange, has a connection device 18 a recording device 19 for the additive container 15 and the adapter 14 on. The cradle 19 , in the 2 schematically as a U-shaped frame 19 ' is shown, limits a receiving area 20 for the additive container 15 and supports the adapter 14 and locking means 21 with the help of the additive container 15 in the recording area 20 the cradle 19 can be fixed so that a connecting piece 22 (please refer 3 ) of the additive container 15 pressure and gas tight against the adapter 14 can be kept pressed.

As in 3 is shown, is the connector 22 from an annular trench 23 surrounded, the inward-looking peripheral surface 24 is designed as a sealing surface, which with a trained example as an O-ring seal 25 on the adapter 14 interacts when the connector 22 in a receiving opening provided for this purpose 26 in the adapter 14 is taken while at the same time the receiving opening 26 surrounding ring section 27 of the adapter 14 in the ditch 23 dips.

If the connection section of the additive container 15 with the adapter 14 connected, simultaneously pushes a hollow pin 28 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 hole 30 ' to the connection line 13 can flow, depending on the installation conditions with a union nut 31 - as in 3 represented - or via an unillustrated angle piece with a connection piece 32 of the adapter 14 connected is.

One in the cradle 19 arranged and fixed additive container 15 to replace one another, first becomes a support element 33 of the locking means 21 , which is shown as a support plate, by appropriate adjusting means 34 , which are indicated here as screws, from the in 2 shown position moves to the left, so that the additive container 15 with its connection section from the adapter 14 pulled off and out of the receiving area 20 the cradle 19 can be removed.

Subsequently, a full additive container 15 in the recording area 20 inserted and with its connection area so against the adapter 14 pushed that ring section 27 of the adapter 14 in the ditch 23 and the connector 22 of the additive container 15 in the receiving opening 26 of the adapter 14 dips. Then the support element 33 against the bottom of the additive container 15 moved until it rests against it and now the additive container 15 continue towards the adapter 14 pushes until the seal 25 in sealing engagement with the peripheral surface 24 of the trench 23 occurs and the hollow pin 28 the outlet valve 29 of the additive container 15 has opened, leaving additive from the additive container 15 over to the adapter 14 connected line arrangement, schematically in the drawing as a connecting line 13 is indicated, the metering pump 10 can flow.

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

To an additive from the additive container 15 in the gas tank 12 to supply sucks the activated via the control signal S _p metering pump 10 Additive from the additive container 15 and conveys it at high pressure, for example 15 bar via the pressure line 11 intermittently in the gas tank 12 , The delivery rate of the pump per pump cycle or pulse is, for example, 0.02 ml and determines the size and consistency essentially the dosing accuracy. 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 conveyed into the gas tank, the number N of pump cycles or surges resulting from the metering pump results 10 must run from the quotient of to the gas tank 12 amount of additive M _{T to be} supplied divided by the delivery volume M _F per pump cycle.

To complete a complete emptying of the additive container 15 to allow this is advantageously formed by a two-chamber container Ge, one chamber is a flexible plastic or aluminum bag containing the additive, while the other chamber is formed by the space between the plastic or aluminum bag and the outer wall of the container. 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 in 4 shown, the control device 16 a monitoring circuit 41 on which the 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 _min and stores the current level signal Fact as a level signal F _min , when the current level signal F _{act is} smaller than the previously stored level signal F _min , in a memory 42 , 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 _act becomes F _max in the memory 42 stored. 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. This is what the monitoring circuit recognizes 41 in that the refueling process has ended and then activates a calculation circuit 43 , the amount of additive to be supplied to the gas tank M _T from the difference between the level F _min before refueling and the level F _max after refueling multiplied by the desired additive concentration K _a in the gas used as fuel, in particular LPG. The arithmetic circuit 42 supplies the calculated additive amount M _T to a control signal generator 44 and to a monitoring circuit 45 indicating the filling condition of the additional container 15 monitored in good time before completely draining the auxiliary tank 15 to deliver a corresponding warning signal S _W.

The control signal generator 44 determined from the gas tank 12 amount of additive to be supplied M _T the number of the metering pump 10 to be executed pump cycles or pump surges and controls them accordingly.

The monitoring circuit 45 calculates the filling level of the additive container 15 as the difference between the filling state M _B before refueling and the gas tank 12 supplied additive amount M _T and compares the filling amount M _B after refueling with a limit value M _g and outputs a warning signal S _W , 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 Not only is stored, but also can be displayed by means of a suitable analog or digital display, as in 4 by the dashed arrow line and the numbers on a display device 49 a user interface 47 is indicated.

To after a change of the additive container 15 the filling state value M _B for the additive container 15 to reset to its original value, is conveniently a manually operated reset switch 46 provided after replacement of an additive container 15 is pressed. The reset switch 46 is part of the user interface 47 , which as further input means, for example, a four-way joystick 47 ' , a keypad 47 '' so-called touchpad (touch screen) or the like may have. It also has the user interface 47 a display device, e.g. As an LCD display 49 for displaying corresponding output data of the control device 16 ,

As 5 shows, has a control device 16 ' According to another embodiment of the invention for detecting a refueling operation a monitoring circuit 51 on which a fuel tank signal S _t indicative of a refueling operation is supplied. The tank signal S _t can, for example, from a sensor switch 17 ' to the control device 16 ' delivered to a gas filling port 12 ''' at the gas tank 12 is provided, as in 1 indicated by dashed lines.

If the tank signal S _t indicates that a refueling process has been initiated, then the monitoring circuit initiates 51 in that the current fill level signal F is indicative of the minimum fill level signal F _min in the memory 42 is stored. After completion of the refueling process, which is also indicated by the tank signal S _t , then the now existing level signal F is 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 accepted. After completion of the refueling process, a start signal from the monitoring circuit can be issued 51 out, as described above, from the computing circuit 43 from the fill levels before and after refueling the gas tank 12 taking into account the desired additive concentration K _a in the gas, the corresponding additive amount M _T be calculated. The control of the dosing pump 10 and monitoring the filling state of the additive container 15 then takes place in the same way as described above.

The additive dosing system according to the invention is particularly suitable for retrofitting motor vehicles that can operate conventional internal combustion engines both with conventional liquid fuels, such as gasoline, and with gas, in particular LPG. 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 plant or subsequently, it is particularly expedient that only an external signal is required in addition to the power supply to a to ensure reliable delivery of the precisely metered amounts of additive into the gas tank.

In the event that it is necessary, because of a changed composition of the fuel gas to adjust the concentration of the additive therein differently, the corresponding concentration value K _a via the user interface 47 be changed. This may be done, for example, by directly inputting a corresponding additive concentration value for a particular fuel gas composition, or by setting the corresponding concentration values for the various fuel gas compositions in the reservoir 42 are stored so that only the appropriate gas or liquefied gas mixture needs to be specified.

With Help of the additive dosing system according to the invention can thus be ensured that a conventional Engine reliable against damage when operating with gas is protected without the user at every refueling in a complicated way for an additive intake would have to provide the gas tanked.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 3924596 C1 [0004]
• - DE 3337983 A1 [0005]

Claims (17)

Additive dosing system for gas-fueled internal combustion engines, with - a metering pump ( 10 ) whose pressure side via a pressure line ( 11 ) with a gas tank ( 12 ) of an internal combustion engine is connectable, - a connecting device ( 18 ) for an additive container ( 15 ), with which the additive container ( 15 ) via a conduit arrangement ( 13 ) to the suction side of the metering pump ( 10 ), and - a control device ( 16 ) for controlling the metering pump ( 10 ) in response to a level signal (F), the control device ( 16 ) from a tank level sensor ( 17 ) at the gas tank ( 12 ) can be fed. Additive dosing system according to claim 1, characterized in that the metering pump ( 10 ) is a suction and pressure pump, which in operation the additive for metering under high pressure intermittently in the gas tank ( 12 ). Additive dosing system according to claim 2, characterized in that the metering pump ( 10 ) in operation, 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 about 15 bar. Additive dosing system according to claim 1, 2 or 3, characterized in that the connecting 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 suction side of the dosing pump ( 10 ) leading line arrangement ( 13 ) having. Additive dosing system according to claim 4, characterized in that the adapter ( 14 ) a receiving opening ( 26 ) for the connector ( 22 ) of the additive container ( 15 ) and a receiving opening ( 26 ) has surrounding seal, which with a the connecting piece ( 22 ) surrounding sealing surface on the additive container ( 15 ) interacts when an additive container ( 15 ) with its connection piece ( 22 ) into the receiving opening ( 26 ) is inserted to the additive container ( 15 ) pressure-tight with the suction side of the dosing pump ( 10 ) leading line arrangement. Additive dosing system according to claim 5, characterized in that a hollow pin ( 28 ) for opening an outlet valve ( 29 ) in the connector ( 22 ) of the additive container ( 15 ) centrally into the receiving opening ( 26 ) for the connector ( 22 ) protrudes. Additive dosing system according to claim 4, 5 or 6, characterized in that the receiving device ( 19 ) for pressure and gas-tight fixing of the connection piece ( 22 ) of an additive container ( 15 ) in the adapter ( 14 ) Has locking means by which the additive container ( 15 ) against the adapter ( 14 ) is printable. Additive dosing system according to one of the preceding claims, characterized in that the control device ( 16 ) has a monitoring circuit for detecting a refueling operation that compares a current level signal with a stored level signal and that detects a refueling event when the current level signal indicates a higher tank level than the stored one. Additive dosing system according to one of claims 1 to 7, characterized in that - the control device ( 16 ) a tank signal can be fed from a sensor switch arranged at a gas filling connection of the gas tank, and - the control device ( 16 ) has a monitoring circuit for detecting a refueling operation that monitors the tank signal. Additive dosing system according to one of the preceding claims, characterized in that the control device ( 16 ) a computing circuit ( 43 ) for determining the to the gas tank ( 12 ) to be supplied amount of additive from a current and a stored level signal and a control signal transmitter ( 44 ), the control signals generated in dependence on the determined amount of additive to the metering pump ( 10 ). Additive dosing system according to one of the preceding claims, characterized in that the control device ( 16 ) a monitoring circuit ( 45 ) for determining the level of the additive container ( 15 ), whose level from the to the gas tank ( 12 ) and controls a warning and / or level indicator according to the level of the additive container. Additive dosing 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 determining the level of the additive container ( 15 ) is reset when changing the same. Method for metering an additive into a gas tank of a gas-fueled internal combustion engine, comprising the following steps: - detecting a gas tank during a refueling operation ( 12 ) amount of gas supplied, in particular Amount of liquefied petroleum gas, - calculating the quantity of additive required for the quantity of gas supplied, in particular the amount of liquid gas, on the basis of a set metering quantity, and - supplying the calculated amount of additive into the gas tank ( 12 ), wherein the additive by means of a metering pump ( 10 ) under pressure into the gas tank ( 12 ) is injected. A method according to claim 13, characterized in that the additive from the metering pump ( 10 ) intermittently into the gas tank ( 12 ) is injected. Method according to claim 14, characterized in that that from the calculated additive amount and the flow rate per injection stroke the number of injections is determined. A method according to claim 13, 14 or 15, characterized characterized in that for detecting a refueling a current Level signal with a stored level signal is compared and that a refueling process is detected when the current Level signal a higher tank level indicates as the stored. A method according to claim 13, 14 or 15, characterized characterized in that for detecting a refueling process monitors a tank signal that is from one at a gas filling port of the gas tank arranged sensor switch is delivered.