Heating device for a device for receiving and supplying liquid reducing agent

Abstract

Heating device for a device for receiving and supplying liquid reducing agent, this device comprising a tank and a pot-shaped container extending into the interior of the tank, wherein the container provides at least one conveying unit for the reducing agent and a connection for dispensing the reducing agent, and with means for attaching the container to or in the tank, further comprising a module insert which has a support body, wherein the support body accommodates at least the conveying unit and the connection for dispensing the reducing agent, and wherein the module insert and / or the support body and / or parts of the tank are multi-layered and one of the layers accommodates electrical heating elements or electrical heating elements are embedded in at least one of the layers, characterized in that the module insert and / or the support body consists of a two-dimensional plastic base material.on which heating elements are fixed in a form-fit and / or material-fit manner, wherein after fixing the heating elements a three-dimensional deformation of the plastic starting material takes place and subsequently the three-dimensional structure is overmolded with another, preferably plastic, material.

Description

The invention relates to a heating device for a device for receiving and supplying liquid reducing agent, this device comprising a tank and a pot-like container which extends into the tank interior, wherein at least one conveying unit for the reducing agent and a connection for discharging the reducing agent are provided in the container, according to the preamble of claim 1.Exhaust gases, in particular of mobile internal combustion engines, are purified by exhaust gas treatment devices of the prior art which treat the exhaust gas of the internal combustion engine with the aid of a reducing agent supplied to the exhaust gas.One of these exhaust gas purification methods is based on selective catalytic reduction, in which the exhaust gases of the internal combustion engine are purified from nitrogen oxide compounds. In this regard, a medium reducing the nitrogen oxide compounds is supplied to the exhaust gas. Ammonia, for example, is used as the reducing medium. In the practical application of such a reduction method, a storage container for the reducing agent must be present in the motor vehicle and, in addition, care must be taken to transport the reducing agent to a so-called injector. The reducing agent used in the current state of the art is a urea-water solution available under the trade name AdBlue.DE 10 2010 010 528 A1 discloses an apparatus for providing such a liquid reducing agent, comprising a reducing agent tank for storing the reducing agent, wherein the tank has at least one heater and this heater is arranged movably in the reducing agent tank and is designed as a so-called active heater. The heating ensures that the aforementioned urea-water solution cannot be frozen or thawed in the frozen state at low temperatures.In the reducing agent tank with temperature sensor according to DE 10 2010 047 277 A1, an insert is located in the tank itself. A temperature sensor is provided on the insert for determining the temperature of the reducing agent through a metallic wall portion. On the basis of the determined temperature, a corresponding heating device is then controlled in order to prevent the already mentioned freezing of the reducing agent.In the container system according to DE 10 2004 046 224 B4, a pump mechanism is integrated in the container, wherein the pump mechanism can be introduced into the container through a bung hole and in this respect a pump lance is also connected to the pump mechanism. The pump head is separable from the pump mechanism and provided with an integrated drive motor, wherein the pump mechanism separated from the pump head is inserted into the bung hole of the container in such a way that the container with the inserted pump mechanism forms a sealingly closed unit. The pump head furthermore comprises a connecting flange for the force- and form-fit connection of the pump head to the pump mechanism.The tank arrangement according to DE 10 2011 081 489 A1 starts from a reducing agent tank and a conveying device assigned to the tank, which is located outside the tank. A fluid connection is present between the conveying device and the tank. This is designed as an intake line and extends into a so-called slosh pot, the latter being fixed firmly in the interior of the tank, in particular in a collar-shaped recess provided there.DE 10 2010 014 314 A1 shows a device for providing liquid reducing agent, which shows a tank having an interior and a container arranged at least partially in the interior of the tank.This container has a filter on the outside with a corresponding filter surface and filter depth. In the container there is a conveying unit for the reducing agent. The conveying unit is connected to a removal point for the reducing agent. The container according to DE 10 2010 014 314 A1 can be partially cast into the wall of the tank, so that a fluid-tight connection is produced. However, it is also possible for a flange to be cast onto the tank, to which flange the container is detachably fastened. Preferably, the container is mounted in an opening in a tank wall of the tank. The container is in this respect of pot-shaped design with a pot base and a cylindrical pot wall and an open side. In this case, the container is preferably inserted into the tank wall in such a way that the container closes the opening in the tank wall. As already explained, the container accommodates the delivery unit, designed as a pump, a return valve, a sensor and at least one heater for heating frozen reducing agent. Preferably, all the enumerated components are present in the container.The device according to DE 10 2010 014 314 A1 provides a large filter surface for the reducing agent, wherein the risk of filter plugging is reduced.EP 1 667 490 A1 discloses a plastic component for heating a fluid, wherein the plastic component consists at least partially of an electrically conductive polymer.Furthermore, EP 0 250 720 A1 discloses a solution of a liquid filter for diesel fuels, wherein defined wall regions of the filter housing are designed as a filter heater. In this regard, the walls of the housing are made entirely or partially of electrical plastic.US 2010 / 0220984 A1 discloses a heating device for a device for receiving and providing liquid reducing agent. The device consists of a tank and a pot-like container which extends into the tank interior. In the container, at least one conveying unit for the reducing agent and a connection for discharging the reducing agent are provided. A flexible heater is also provided, which has a carrier body, wherein said carrier body accommodates at least the conveying unit and the connection for discharging the reducing agent.DE 10 2008 011 464 A1 discloses an exhaust gas aftertreatment system which has a metering device for a pollutant-reducing medium. In this regard, the storage tank for receiving such a medium is disclosed, wherein the storage tank has a tank wall in the form of a layer structure. One of the layers consists of a heating foil in order to temperature control the tank or the tank contents.The device with a tank and a delivery unit for reducing agents for minimizing pollutant gases according to DE 10 2010 004 612 A1 comprises a chamber in which the delivery unit is arranged, wherein the chamber has a heater.From the foregoing it is therefore the object of the invention to specify an improved heating device for a device for receiving and providing liquid reducing agent, which heating device can be produced in a simple manner and which satisfies the specific conditions, in particular the necessary reagent resistance.The object of the invention is achieved by the combination of features according to claim 1, wherein the dependent claims comprise expedient embodiments and developments.Accordingly, a device for receiving and providing liquid reducing agent is used as the starting point, which consists of a tank and a pot-like container reaching into the tank interior. In the container there are at least one conveying unit for the reducing agent, optionally a sensor and a connection of the reducing agent. Furthermore, means for fastening the container in or on the tank are formed.Furthermore, a module insert is provided which has a carrier body. This carrier body preferably accommodates only the conveying unit and the sensor and, if appropriate, the connection for discharging the reducing agent, and functionally required electrical and / or hydraulic connections are realized on or by means of the carrier body in such a way that the module insert can be removed in a simple manner for maintenance and service purposes and can be exchanged if appropriate. In principle, the module insert or the carrier body should thus only accommodate the components essential to the function, which are usually subject to wear and a certain probability of failure. These are generally the delivery unit, i.e. the reducing agent pump and a sensor, in particular a pressure sensor for monitoring the pressure conditions in the reducing agent supply system that can be varied via the pump, preferably for a system that is used in a motor vehicle.In an embodiment, the carrier body comprises a carrier plate which is designed as an electrical wiring carrier or accommodates such a wiring carrier. A multilayer printed circuit board or a carrier plate with lead frame contacting means, for example, can be used here. The sensor which is located on the carrier body is preferably designed as a pressure and / or temperature sensor or as a corresponding combined sensor.The carrier body furthermore has a central electrical connection unit, which can be, for example, a multiple contact plug or a multiple contact socket, which is usually used in motor vehicles. A so-called Fakra connection is also conceivable here.The module insert is designed as an exchangeable cartridge-like structure which is easily accessible, for example after removal of a cover, and without additional tool applications.In the space between the container and the module insert, a filter unit for the reducing agent can be arranged in a manner known per se.Because the module insert can be removed in a simple manner, there is also easy access to the filter unit, which in this respect is likewise easily replaceable.The pot-like container can be part of a flange of the tank. In this respect, the pot-like container can be formed integrally with the tank or the tank body.The module insert preferably consists of a plastic material which is resistant to the reducing agent, in particular an HDPE material.In a preferred embodiment, the module insert has an irregular geometric shape which is complementary to a respective receptacle in the container or a flange section of the container in order to enable installation or replacement in a positionally and subsequent manner, i.e. in a positionally appropriate manner.Furthermore, the module insert and / or the carrier body and / or the container and / or at least parts of the tank base and / or of the tank wall are of multilayer design and one of the layers accommodates electrical heating elements or electrical heating elements are embedded in at least one of the layers.According to the invention, a two-dimensional plastic starting material for the module insert or the carrier body or the tank base is initially used as the starting material. The electrical heating elements are fixed onto this two-dimensional plastic starting material in a form-fitting and / or materially integral manner. After the fixing of the heating elements, the two-dimensional plastic starting material is transformed into the desired three-dimensional finished structure.During this forming step or subsequent to the forming step, the three-dimensional structure is injection-molded, so that the desired reagent resistance is created.In particular, in order to ensure the desired installation in liquid tanks, the plastic carrier equipped with the heating conductor material is encapsulated by injection molding with a PE material. If the plastic starting material likewise consists of PE, a secure connection is obtained between the plastic carrier and the injection molding as well as an optimization of the desired heat transfer.In a particularly preferred embodiment, the electrical heating conductor is fixed on the plastic carrier starting material by embroidering. In this respect, a yarn or a corresponding thread produced by textile technology and processed accordingly can be used as the heating conductor.In a further development, the tank base and the container are manufactured in one piece and each have an injection-molded structure of electric heating elements. It should be noted at this point that the container can also be designed as a tank flange module, wherein the tank flange module then directly receives the module insert with the functional assemblies carrier body, pump, sensor, etc.The aforementioned possibility of forming a quasi-heated tank bottom and / or heated tank walls takes place depending on the size and volume of the tank and the position provided in the motor vehicle. It is essential here that freezing of the reducing liquid is prevented under all operating conditions and safe operation of the relevant exhaust gas purification system is ensured.By segmenting the heating elements into heating conductor groups, it is possible to control the heating power according to the respective ambient temperatures and the respective operating conditions or to concentrate the supply of heat energy to specific spatial regions within the tank, in order to ensure, for example, rapid thawing of the reducing liquid and rapid startup of the plant.

Claims

Heating device for a device for receiving and providing liquid reducing agent, this device comprising a tank and a pot-like container which extends into the tank interior, wherein at least one conveying unit for the reducing agent and a connection for dispensing the reducing agent are provided in the container, and comprising means for fastening the container to or in the tank, wherein a module insert is furthermore formed which has a carrier body, wherein said module insert receives at least the conveying unit and the connection for dispensing the reducing agent, and the module insert and / or the carrier body and / or parts of the tank are of multilayer design, and one of the layers receives electrical heating elements or electrical heating elements are embedded in at least one of the layers, characterized in that the module insert and / or the carrier body consists of a two-dimensional plastics starting material, to which heating elements are fixed in a form-fitting and / or firmly bonded manner, wherein after fixing the heating elements a three-dimensional forming of the plastic starting material takes place and subsequently the three-dimensional structure is injection-molded with a further, preferably plastic material.Device according to claim 1, characterised in that the electrical heating elements are fixed to the plastic starting material by embroidering.Device according to one of the preceding claims, characterized in that the electrical heating elements consist of conductive threads or yarns which can be processed by means of textile technology methods.Device according to claim 1, characterised in that the heating elements are produced by printing on the plastic starting material by means of conductive paste.