internal combustion engine

Abstract

Internal combustion engine with urea water solution injection in the exhaust system, comprising at least one urea water solution tank (7), at least one pump, at least one intake line leading to the pump, at least one urea water solution metering valve (8) connected to the pump by means of a pressure line, and at least one return line leading from the pump to the urea water solution tank (7) and having a filter element arranged at the end opposite the pump, as well as at least one urea water solution sensor arranged in the urea water solution tank (7), wherein the urea water solution tank (7) contains a filter (1) on the return line for bubble separation and a filter (2) on the intake line.

Description

[0001] The invention relates to an internal combustion engine with urea water injection in the exhaust system, comprising at least one urea water tank, at least one pump, at least one intake line leading to the pump, at least one urea water metering valve connected to the pump via a pressure line, and at least one return line leading from the pump to the urea water tank, at the end of which a filter element is arranged, as well as at least one urea water sensor arranged in the urea water tank. The invention further relates to a method for degassing and filtering urea water, for use in such an internal combustion engine.

[0002] Degassing is the controlled removal of gases and other volatile substances from liquids and solids.

[0003] The removal of dissolved substances or substances trapped as bubbles prevents other negative effects such as hydrogen embrittlement of steel, deterioration of materials due to oxidation, hydrolysis due to moisture, corrosion of steam boilers, pipelines, etc. due to oxygen and carbon dioxide in the liquid, and failure of hydraulic systems due to increased compressibility. The most common method for degassing is to subject the material to be degassed to a vacuum. When ultrasound is introduced into a liquid, e.g. via a sonotrode, a high-frequency alternating pressure field builds up within it. The periodically occurring, short-term negative pressure causes cavities to form. This effect is known as cavitation. The cavities arise, for example, from gas inclusions that act as cavitation nuclei.The dissolved gas diffuses into the cavitation bubbles and prevents them from completely imploding again during the subsequent pressure increase: The bubbles grow with each oscillation. If standing waves form due to reflections, the bubbles are forced to their nodes, where they coalesce (coalescence) and, due to buoyancy, eventually migrate to the surface. Due to the temperature dependence of Henry's law constant, degassing can also be achieved simply by increasing the temperature. The simplest method is the addition of energy at reduced pressure and is known as boiling in a vacuum. This effect can be observed during normal boiling, where air bubbles form in the water.

[0004] Such devices are disclosed, for example, in WO 2013 / 029 950 A1, where air bubbles are captured using so-called gas traps, or in DE 10 2007 012 918 A1, where air bubbles are generated by the high-frequency opening and closing of a liquid valve and retained in a filter. The disadvantage of this is that, as in the case of WO 2013 / 029 950 A1, the gas bubbles tend to linger randomly in different locations. Or, as in DE 10 2007 012 918 A1, bubbles are generated instead of removed. Such devices are also known from DE 11 2014 002 334 T5, DE 10 2009 000 097 A1, and US 2014 / 0 166 126 A1.

[0005] The object of the present invention is to avoid the above-mentioned disadvantages and to provide a device and a method that reliably degasses or filters a urea water solution.

[0006] The object is achieved by an internal combustion engine according to claim 1 and by a method according to claim 9.

[0007] The urea water solution sensor measures the urea content in the water solution. This is done, for example, by measuring the density using ultrasound or infrared measurement. Bubbles in the sensor's measuring path distort the measurement result. The advantage of the invention is the prevention or reduction of bubbles (which may have formed, for example, in the pump or pipes) entering the urea water solution tank, thereby achieving suitable measurement conditions for the urea water solution sensor.

[0008] In an advantageous further development, it is provided that the filter is a precoat filter or a candle filter or a spatial filter or a stratified bed filter or a magnetic filter.

[0009] Another advantageous further development provides that the filter contains flexible filter media or rigid filter media or packed layers.

[0010] An advantageous further development provides that the filter material is a sieve or a paper filter or a glass fiber fleece or ceramic or sintered metal or needle felt.

[0011] In a further advantageous development, the pore size of the filter is smaller than 70 micrometers.

[0012] In another advantageous development, it is provided that the filter is a two-dimensional filter or a three-dimensional filter or a multi-layer or a surface or a depth filter.

[0013] An advantageous further development provides that the urea water solution tank is under vacuum and / or is provided with deaeration additives.

[0014] In a further advantageous development, it is provided that the urea water solution tank has an ultrasonic generator and / or a heater, wherein the ultrasonic generator is arranged in the quality sensor.

[0015] Exemplary embodiments of the invention are described in the figures and explained in more detail in the following description.

[0016] They show: Fig. 1: a schematic representation of the urea water solution tank up to the injection valve Fig. 2: a schematic representation of the internal combustion engine with urea water solution tank and dosing valve Fig. 3: a variant of the representation in Fig. 2 with return from the dosing valve

[0017] Fig. Figure 1 shows a schematic representation of the urea water solution tank 7, which contains urea water solution and a quality sensor 3. A suction line is arranged in the urea water solution tank 7, at one end of which a filter is located, and at the other end of which the urea water solution pump 6 is located. A return line is also arranged on the pump 6, on the side opposite the pump, a filter 1 is located to retain air bubbles. A pressure line leads from the pump 6 to the urea water solution dosing valve 8.

[0018] In Fig. Figure 2 shows a schematic representation of the internal combustion engine with urea water solution tank 7, control unit (ECU), urea water solution pump 6, and metering valve 8 metering into the exhaust tract. The urea water solution tank 7 contains a filter 1 on the return line for bubble separation, a filter 2 on the suction line, a quality sensor 3, a fill level sensor 4, and a temperature sensor 5, all connected to the control unit (ECU) of the internal combustion engine (ICE). A suction line is arranged in the urea water solution tank 7, at one end of which a filter 2 is arranged, and at the other end of which the urea water solution pump 6 is arranged. A return line is also arranged on the pump 6, on the side of which, opposite the pump 6, a filter 1 is arranged to retain air bubbles.A pressure line leads from pump 6, controlled by the ECU, to the urea water dosing valve 8, which doses urea water into the exhaust system and is also controlled by the ECU of the internal combustion engine (ICE). A pressure sensor, a temperature sensor, and a NOx sensor are located between the internal combustion engine (ICE) and the catalytic converter in the exhaust system of the internal combustion engine (ICE), all of which are connected to the ECU of the internal combustion engine (ICE). A temperature sensor and a NOx sensor are located in the exhaust system of the internal combustion engine (ICE) downstream of the catalytic converter, both of which are connected to the ECU of the internal combustion engine (ICE).

[0019] Fig.Figure 3 shows a schematic representation of the internal combustion engine with urea water solution tank 7, control unit (ECU), urea water solution pump 6, and metering valve 8 metering into the exhaust tract. The urea water solution tank 7 contains a filter 1 on the return line for bubble separation, a filter 2 on the suction line, a quality sensor 3, a level sensor 4, and a temperature sensor 5, all connected to the control unit (ECU) of the internal combustion engine (ICE). A suction line is arranged in the urea water solution tank 7, at one end of which a filter 2 is arranged and at the other end of which the urea water solution pump 6 is arranged. A return line is also arranged on the urea water solution metering valve 8, on the side of which, opposite the pump 6, a filter 1 is arranged to retain air bubbles.A pressure line leads from pump 6, controlled by the ECU, to the urea water dosing valve 8, which doses urea water into the exhaust system and is also controlled by the ECU of the internal combustion engine (ICE). A pressure sensor, a temperature sensor, and a NOx sensor are located between the internal combustion engine (ICE) and the catalytic converter in the exhaust system of the internal combustion engine (ICE). A temperature sensor and a NOx sensor are located in the exhaust system of the internal combustion engine (ICE) downstream of the catalytic converter, both of which are connected to the ECU of the internal combustion engine (ICE). List of reference symbols 1 filter on the return line for bubble separation 2 filters on the suction line 3 Quality sensor 4 Level sensor 5 Temperature sensor 6 Urea water solution pump 7 Urea water solution tank 8 Urea water solution dosing valve ECU Engine Control Unit ICE Internal Combustion Engine

Claims

[1] Internal combustion engine with urea water solution injection in the exhaust system, comprising at least one urea water solution tank (7), at least one pump, at least one intake line leading to the pump, at least one urea water solution metering valve (8) connected to the pump by means of a pressure line, and at least one return line leading from the pump to the urea water solution tank (7) and having a filter element arranged at the end opposite the pump, as well as at least one urea water solution sensor arranged in the urea water solution tank (7), wherein the urea water solution tank (7) contains a filter (1) on the return line for bubble separation and a filter (2) on the intake line. [2] Internal combustion engine according to claim 1, characterized by that the filter (1, 2) is a precoat filter or a candle filter or a spatial filter or a stratified bed filter or a magnetic filter. [3] Internal combustion engine according to one or more of the preceding claims, characterized by that the filter (1, 2) contains flexible filter media or rigid filter media or packed layers. [4] Internal combustion engine according to one or more of the preceding claims, characterized by that the filter material is a sieve or a paper filter or a glass fiber fleece or ceramic or sintered metal or needle felt. [5] Internal combustion engine according to one or more of the preceding claims, characterized by that the pore size of the filter (1, 2) is less than 70 micrometers. [6] Internal combustion engine according to one or more of the preceding claims, characterized by that the filter (1, 2) is a two-dimensional filter or a three-dimensional filter or a multi-layer or a surface or a depth filter. [7] Internal combustion engine according to one or more of the preceding claims, characterized bythat the urea water solution tank (7) is under vacuum and / or is provided with deaeration additives. [8] Internal combustion engine according to one or more of the preceding claims, characterized by that the urea water solution tank (7) has an ultrasonic generator (3) and / or a heater. [9] Method for degassing and filtering urea water solution for use in an internal combustion engine according to one or more of the preceding claims.

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