阅读说明：本技术 安装在用于还原剂的车辆储罐中的加热设备和车辆储罐 (Heating device for installation in a vehicle tank for a reducing agent, and vehicle tank ) 是由 C·沃斯曼 J·霍格森 于 2019-10-01 设计创作，主要内容包括：本发明涉及一种安装在用于还原剂(14)的车辆储罐(11)中的加热设备(1),该还原剂能够被加入到机动车的排气流中以用于排气后处理。所述加热设备包括至少一个电加热元件(2)和热分配体(4),其中,该至少一个电加热元件(2)包括PTC加热元件(3),该PTC加热元件布置成与热分配体(4)传热地接触。根据本发明,该热分配体(4)具有导热装置(6),该导热装置被设计成用于将来自PTC加热元件(3)的热量有针对性地在热分配体(4)内部进行分配。本发明还涉及一种具有这种加热设备(1)的车辆储罐(11)。(The invention relates to a heating device (1) which is installed in a vehicle tank (11) for a reducing agent (14) which can be added to the exhaust gas flow of a motor vehicle for exhaust gas aftertreatment. The heating device comprises at least one electric heating element (2) and a heat distributing body (4), wherein the at least one electric heating element (2) comprises a PTC heating element (3) arranged in heat transferring contact with the heat distributing body (4). According to the invention, the heat distributor body (4) has a heat conducting device (6) which is designed to distribute the heat from the PTC heating element (3) in a targeted manner within the heat distributor body (4). The invention also relates to a vehicle tank (11) having such a heating device (1).)

1. Heating device (1) installed in a vehicle tank (11) for a reducing agent (14) which can be added to the exhaust gas flow of a motor vehicle for exhaust gas aftertreatment, said heating device comprising at least one electric heating element (2) and a heat distributing body (4), wherein the at least one electric heating element (2) comprises a PTC heating element (3) which is arranged in heat transferring contact with the heat distributing body (4), wherein the heat distributing body (4) is made of a first material having a first thermal conductivity, and wherein the heat distributing body (4) is provided for transferring and dissipating heat generated by the PTC heating element (3), characterized in that heat conducting means (6) are provided on and/or in the heat distributing body (4), which heat conducting means are made of a second material, the second material has a second thermal conductivity which is different from the first thermal conductivity, and the heat-conducting device (6) is designed to distribute the heat from the PTC heating element (3) in a targeted manner within the heat distributor body (4).

2. Heating device (1) according to claim 1, characterized in that the heat distributing body (4) has an abutment face (4) against which the PTC heating element (3) abuts at least partially (5), wherein the heat conducting means (6) comprise a coupling element (8) which is arranged directly between a side (7) of the PTC heating element (3) facing the abutment face and the abutment face (5), wherein the second material of the coupling element (8) has a second thermal conductivity which is higher than the first thermal conductivity.

3. A heating device (1) according to claim 2, characterized in that the coupling element (8) is a metal body, preferably a metal foil or a metal plate.

4. Heating device (1) according to one of the preceding claims, characterized in that the heat conducting means (6) comprise at least one thermally insulating layer (9a, 9b, 9c) which is arranged at least partially on the surface (4) of the heat distributing body, wherein the second material of the at least one thermally insulating layer (9a, 9b, 9c) has a second thermal conductivity which is lower than the first thermal conductivity.

5. Heating device (1) according to one of the preceding claims, characterized in that the heat conducting means (6) have at least one heat conducting element (10) which is arranged at least in a partial region within the heat distributing body (4), wherein the at least one heat conducting element (10) is designed for preventing or at least reducing heat dissipation into the surroundings of the heat distributing body (4).

6. Heating device (1) according to one of the preceding claims, characterized in that the first material is aluminium.

7. Heating device (1) according to one of the preceding claims, characterized in that the heat distributing body (4) is designed substantially basin-shaped.

8. A vehicle tank (11) for a motor vehicle, which vehicle tank is designed for storing a reducing agent (14) which can be added to the exhaust-gas flow of a motor vehicle for exhaust-gas aftertreatment, wherein the vehicle tank comprises a heating device (1) according to one of claims 1 to 7.

Technical Field

The invention relates to a heating device installed in a vehicle tank for a reducing agent which can be added to the exhaust gas flow of a motor vehicle for exhaust gas aftertreatment, comprising at least one electric heating element and a heat distributor body, wherein the at least one electric heating element comprises a PTC heating element which is arranged in heat-transferring contact with the heat distributor body. The heat distribution body is made of a first material having a first thermal conductivity, wherein the heat distribution body is provided for transmitting and dissipating heat generated by the PTC heating elements. The invention also relates to a vehicle tank for a motor vehicle with such a heating device, which vehicle tank is designed for storing a reducing agent that can be added to the exhaust gas flow of the motor vehicle for exhaust gas aftertreatment.

Background

For reducing nitrogen oxides emitted by internal combustion engines in motor vehicles, it is known to inject a liquid reducing agent into the exhaust gas stream in a Selective Catalytic Reduction (SCR) process in order to convert the nitrogen oxides (NOx) contained in the exhaust gas stream into harmless components, such as nitrogen (N), using a catalyst₂) And water (H)₂O). Ammonia (NH) is generally used as the reducing agent₃) And/or reducing agent precursors, e.g. urea (CH)₄N₂O) or an aqueous urea solution. The reducing agent precursor has been demonstrated to be a 32.5% aqueous urea solution, available under the trade nameAnd (4) obtaining.

For storing the liquid reducing agent, a storage tank is used, which cooperates with a delivery unit for delivering the reducing agent from the storage tank to the exhaust gas flow. In the delivery and storage of liquid reducing agents, it is necessary to take into account that liquid reducing agents, in particular aqueous urea solutions, can at least partially freeze.The freezing point of the reducing agent precursor is typically about-11 ℃.

This leads to the problem that, in particular during cold starts or restarts of the motor vehicle, no or only very limited liquid form of the reducing agent can be supplied to the exhaust system. At the same time, it must be ensured that the nitrogen oxides in the exhaust gas flow are reduced even in the case of very low ambient temperatures of the motor vehicle. Measures are therefore taken to reduce icing and/or to rapidly melt the icing reductant in the tank. For this purpose, a tank for storing the reducing agent is usually provided with a heating device in order to keep at least a portion of the reducing agent in the tank in a liquid state or converted to a liquid state at low temperatures, so that it can then be added to the exhaust gas stream.

Such heating devices typically comprise PTC (positive temperature coefficient) heating elements. Such thermistors, also known as positive temperature coefficient thermistors, convert electrical current into heat and the resistance is particularly temperature dependent. The PTC heating element therefore has a low resistance at low temperatures, and the resistance increases exponentially above a defined switching temperature. By this feature, the PTC heating element is able to self-regulate: when a large current flows at a low temperature, the PTC element is rapidly heated and has a high heating power. Once the switching temperature is reached, the current through the PTC element decreases and prevents the temperature from significantly exceeding the switching temperature, thereby correspondingly reducing the heating power.

A heating device and a vehicle tank of the type mentioned at the outset are disclosed, for example, in DE 102006027487 a 1. The heating device is arranged in a tank for the liquid reducing agent and has a flat aluminum body designed as a heat distribution body, in which a plurality of electric heating elements are integrated. These electric heating elements are PTC heating elements which transmit heat to the planar aluminum body. Heat is transferred to the reducing agent via the aluminum body. The frozen reducing agent is melted by the heating device, so that a liquid reducing agent is available even at low temperatures, which can be delivered to the exhaust system by the delivery module.

Furthermore, DE 102007059848 a1 describes a device which can be inserted into a container for storing liquidsThe heating device in the storage tank of (1). The heating device has a heating resistor with a positive temperature coefficient, which is surrounded by a ribbed aluminum body.

EP 1767417 a1 also discloses a tank for a urea solution with a heating device arranged in the tank. The heating device has a rod-shaped PTC heating element, which is connected in a heat-conducting manner to a heat distribution element. The distribution element has a melting sleeve with a plurality of plate-shaped deicing surfaces. In operation, the PTC heating element dissipates heat through the melt sleeve to the de-icing surface of the heat distribution element, thereby substantially transferring heat through the de-icing surface to the frozen urea solution in the storage tank.

However, it is particularly disadvantageous in heating devices of this type that the heat generated by the PTC heating element and transferred to the heat distributor body is transferred essentially uncontrolled by the heat distributor body into the surroundings and/or into the reducing agent. This can result, in particular if the vehicle tank contains less reducing agent, in that more heat can be transferred per unit time from the PTC heating element to the heat distributor than can be transferred and dissipated per unit time by the heat distributor. This increases the temperature of the PTC heating element in particular, which ultimately leads to a reduction in the heating output or to the switching off of the PTC heating element. In this case, at least temporarily, only a reduced heating power or no heating power is available for heating the reducing agent.

Summary of the invention, objects, solutions, advantages

It is therefore a first object of the present invention to provide a heating device installed in a liquid storage tank for a reducing agent which can be added to the exhaust-gas flow of a motor vehicle for exhaust-gas aftertreatment, which heating device ensures a heating of the reducing agent which is as reliable and rapid as possible while ensuring a heating output which is as uniform as possible. A second object on which the invention is also based is to specify a vehicle tank for a motor vehicle with a heating device, which vehicle tank is designed for storing a reducing agent that can be added to the exhaust-gas flow of the motor vehicle for exhaust-gas aftertreatment. In this vehicle tank, the most reliable and rapid heating of the reducing agent is ensured while at the same time ensuring the most uniform heating power possible.

According to the invention, the first object is achieved by the features of claim 1. Advantageous embodiments and further developments are set forth in the dependent claims and the following description.

A heating device installed in a vehicle tank for a reducing agent which can be added to the exhaust gas flow of a motor vehicle therefore has, in a known manner, at least one electric heating element and a heat distributor body, wherein the at least one electric heating element has a PTC heating element which is arranged in heat-conducting contact with the heat distributor body. The heat distribution body is made of a first material having a first thermal conductivity, wherein the heat distribution body is provided for transmitting and dissipating heat generated by the PTC heating elements.

According to the invention, a heat conducting device is provided on and/or in the heat distributor body, which heat conducting device is made of a second material having a second thermal conductivity that is different from the first thermal conductivity, wherein the heat conducting device is designed to distribute the heat from the PTC heating elements in a targeted manner within the heat distributor body.

The invention is based on the consideration that a particularly effective heating of the reducing agent in the tank of the vehicle is achieved if the heating power of the PTC heating element is as uniform and high as possible without a significant increase in the temperature of the PTC heating element occurring, in particular without the temperature increasing to the point of reaching or exceeding the switching temperature of the PTC heating element. The invention is based on the consideration that reliable and rapid heating of the reducing agent with uniform heating power is further promoted by heating the entire heat distributor body as far as possible, in particular independently of the reducing agent level in the vehicle tank. The invention therefore proposes that the heat distributor body has a heat conducting device which is arranged on and/or in the heat distributor body and is made of a second material having a second thermal conductivity which is different from the first material of the heat distributor body, and that the heat conducting device is designed to distribute the heat of the PTC heating elements in a targeted manner in the heat distributor body. The heat conductivity of the heat distributor can thereby be influenced in such a way that the heat is conducted over the entire heat distributor, and thus a heating of the heat distributor body as completely as possible is achieved, whereby essentially as large a surface of the heat distributor body as possible is provided for heat dissipation. This helps to make the flow of heat transferred from the PTC heating element into the heating device substantially identical to the flow of heat that can be dissipated by the heat distributor to the surroundings and/or the reducing agent, whereby the risk of the PTC heating element "turning off" due to excessive temperatures is greatly reduced in particular and the reducing agent can be heated effectively in a manner that is independent of the reducing agent level in the vehicle tank.

The embodiment according to the invention has the advantage that a heating device is thus provided in which a particularly pronounced heat flow occurs in the heat distributor body, which heating device ensures a heating of the reducing agent as reliably and rapidly as possible while ensuring a heating power which is as uniform as possible.

The term "reducing agent" as used includes not only reducing agents (especially ammonia), but also reducing agent solutions, reducing agent precursors (especially urea), reducing agent precursor solutions (especially urea))。

The heat distributor is provided in particular for conducting and conducting the heat generated by the PTC heating element and transported to the heat distributor to a region further away from the PTC heating element and for dissipating the heat to the reducing agent and/or the surrounding environment.

The heat distributing body may be in direct contact with the PTC heating element. In an advantageous embodiment of the invention, the heat distribution body has an abutment surface against which the PTC heating element abuts at least in regions, wherein the heat conducting device has a coupling element which is arranged directly between a side of the PTC heating element facing the abutment surface and the abutment surface. The second material of the coupling element has a second thermal conductivity, which is higher than the first thermal conductivity. In this way, a particularly good thermal coupling of the PTC heating element to the heat distributor body and a targeted introduction of heat into the heat distributor body as possible can be achieved. The coupling element is preferably designed to be larger in area than the side of the PTC heating element facing the contact surface, so that the contact surface between the contact surface of the heat-conducting device and the coupling element, via which the heat can be transferred from the coupling element to the heat distributor, is designed to be as large as possible.

The coupling element is advantageously made of a second material having a second thermal conductivity that is significantly higher than the first thermal conductivity. The coupling element is particularly advantageously a metal body, preferably a metal foil or a metal plate. Metals generally have high thermal conductivity. By using a metal foil or a metal plate, a lightweight coupling element can be obtained, which moreover requires little installation space.

In a further advantageous embodiment, the heat-conducting device has at least one thermally insulating layer, which is arranged at least in a partial region on the surface of the heat distributor body. The second material of the at least one thermal barrier layer has a second thermal conductivity lower than the first thermal conductivity. This ensures that the heat generated by the PTC heating element and transferred to the heat distribution body is not dissipated, or is dissipated only to a lesser extent, at least in the region of the surface of the heat distribution body, in which the heat insulation layer is arranged, into the surroundings, but remains predominantly in the heat distribution body and can be conducted further in the heat distribution body. The size and/or arrangement of the insulation layer can be determined according to the desired heat conducting properties in the heat distributing body. Preferably, the heat conducting device has a plurality of such thermally insulating layers. In particular the entire region adjacent to the PTC heating element can be embodied with a thermally insulating layer or layers. The heat insulation layer is advantageously made of a second material having a second thermal conductivity that is significantly lower than the first thermal conductivity, preferably a second material having a second thermal conductivity that is significantly lower than the metal.

In a further advantageous embodiment, the heat-conducting device has at least one heat-conducting element which is arranged at least in a partial region within the heat distributor body, wherein the heat-conducting element is designed to prevent or at least reduce the dissipation of heat into the surroundings of the heat distributor body. The heat conducting element influences the heat conduction in the heat distributor in the following manner: that is, in the region of the heat-conducting element, the heat is not dissipated or is dissipated only to a lesser extent into the surroundings, so that the heat remains predominantly in the heat distributor and can be conducted further in the heat distributor. The size and/or arrangement of the heat conducting elements can be determined according to the desired heat conducting properties in the heat distributing body. The heat-conducting device preferably has a plurality of such heat-conducting elements. The heat-conducting element can, for example, be made of a second material, in particular a metal, which has a second thermal conductivity that is higher than the first thermal conductivity, so that it can conduct heat particularly well (further) within the heat distributor body. In this case, the heat-conducting element is arranged in particular as far as possible into the interior of the heat distributor body, so that the distance between the heat-conducting element and the surface of the heat distributor body is as large as possible. The heat conducting element can, however, also be made of a second material, for example, which has a second thermal conductivity that is smaller than the first thermal conductivity, so that the heat conduction is reduced or prevented by the heat conducting element. The heat-conducting element is arranged here in particular as close as possible to the surface of the heat distributor body, so that an insulation is thereby formed inside the heat distributor body. Suitably, a thermally conductive agent is added to the heat distributing body.

The heat distributing body may for example be made of a first material of metal. In an advantageous embodiment, the first material is aluminum. Aluminum has a very high thermal conductivity and thus promotes the conduction and distribution of heat within the heat distributor.

In a further advantageous embodiment, the heat distributing body is substantially basin-shaped. Such a heat distribution body can in particular be inserted from below into a bottom opening of the vehicle tank and, in the assembled state, extends with its substantially cylindrical wall and its bottom from the bottom of the vehicle tank into an interior region of the vehicle tank. This embodiment makes it possible to transfer heat over a particularly large area and thus to achieve a large heat flow to the reducing agent, and thus also to facilitate a reliable and rapid heating of the reducing agent.

The second object is achieved according to the invention by the features of claim 8.

The vehicle tank according to the invention for a motor vehicle is designed for storing a reducing agent which can be added to the exhaust gas flow of a motor vehicle for exhaust gas aftertreatment. The vehicle tank is provided with a heating device according to the invention.

The advantages and preferred embodiments described for the heating device according to the invention also apply correspondingly for the vehicle tank according to the invention.

Drawings

Embodiments of the present invention are explained in more detail below with reference to the drawings. The figures show:

figure 1 shows a schematic cross-sectional view of a heating device,

fig. 2 shows a schematic cross-sectional view of a vehicle tank with a further embodiment of a heating device.

Parts that correspond to each other have the same reference numerals in all the figures.

Detailed Description

A schematic cross-sectional view of an embodiment of a heating device 1 is shown in fig. 1. The heating device 1 has an electric heating element 2, which comprises a PTC heating element 3, and a heat distribution body 4 made of aluminum. The PTC heating element 3 is in thermal contact with the contact surface 5 of the heat distribution body 4.

The PTC heating elements 3 can be supplied with electrical energy via electrical connection lines (not shown in fig. 1) and convert the electrical energy into heat during operation. The resistance of the PTC heating elements 3 is in particular temperature-dependent. Thus, the PTC heating element 3 has a low resistance at low temperatures, which increases exponentially beyond a defined switching temperature. When the switching temperature is reached, the current through the PTC element 3 decreases, so that the heating power decreases accordingly.

The heat distribution body 4 has a heat-conducting device 6, which is arranged in the heat distribution body 4 or on the heat distribution body 4. The heat conducting device 6 is made of a second material having a second thermal conductivity different from aluminum and is designed for the targeted distribution of the heat generated by the PTC heating elements 3 in the heat distributor body 4.

For this purpose, a coupling element 8 is provided between the side 7 of the PTC heating element 3 facing the contact surface 5 and the contact surface 5. The coupling element 8 is designed as a metal plate with a second thermal conductivity higher than aluminum. Furthermore, the coupling element 8 is larger in area than the side 7 of the PTC heating element 3 facing the contact surface 5, so that a large contact surface is formed between the contact surface 5 of the heat distributor body 4 and the coupling element 8, via which surface heat can be transferred from the coupling element 8 to the heat distributor body 4. This makes it possible to provide a particularly good thermal coupling of the PTC heating elements 3 to the heat distributor body 4 and a targeted introduction of heat into the heat distributor body 4 as possible.

Furthermore, an insulating layer 9a is arranged on the surface of the heat distribution body 4 in certain areas. The insulating layer 9a is made of a second material having a second thermal conductivity lower than aluminum. It is thereby ensured that the heat generated by the PTC heating elements 3 and transferred to the heat distributor body 4 is not dissipated or is dissipated only to a lesser extent into the surroundings, at least in the region of the surface of the heat distributor body 4 in which the thermally insulating layer 9a is arranged, but remains predominantly within the heat distributor body 4 and can be conducted further within the heat distributor body.

Furthermore, the surfaces of the heat distribution body 4 close to the heat distribution body 4 are provided in certain regions with heat conducting elements 10. The heat conducting element 10 is designed to prevent or at least reduce heat dissipation into the surroundings of the heat distributing body 4. The heat-conducting element 10 also influences the heat transfer in the heat distributor body 4 in such a way that, in the region of the heat-conducting element 10, no heat is dissipated, or only to a small extent, to the surroundings, but rather the heat is mainly retained in the heat distributor body 4 and can be conducted further within the heat distributor body. The heat conducting element 10 is made of a second material having a second thermal conductivity that is smaller than aluminum, thereby preventing or reducing the conduction of heat through the heat conducting element 10.

By specifically influencing the distribution of heat within the heat distributor body 4 by the heat-conducting device 6, heat conduction can be achieved in particular to extend over the entire heat distributor body and thus to achieve as complete a heating of the heat distributor body 4 as possible. As large a surface of the heat distributor body 4 as possible is thus available for heat dissipation. This helps to bring the heat flow transmitted from the PTC heating elements 3 into the heat distributor body 4 substantially into agreement with the heat flow which can be dissipated by the heat distributor body 4 to the surroundings and/or the reducing agent, whereby in particular the risk of the PTC heating elements "turning off" due to excessive temperatures is greatly reduced and a heating power which is as reliable and uniform as possible can be achieved.

Fig. 2 shows a vehicle tank 11 with an alternative embodiment of the heating device 1 in a schematic sectional view. This heating device 1 corresponds substantially to the heating device 1 shown in fig. 1, wherein the heat distribution body 4 is designed substantially in the form of a basin.

A reductant 14 is present in an interior region 12 of a vehicle tank housing 12. In the region of the bottom 15 of the vehicle tank 11, an opening 16 is provided, through which the heating device 1 is positioned in the interior region 12 of the vehicle tank 11 so as to project inward. The heat distribution body 4 has a surrounding flange-like contact region 17 which is arranged sealingly on the outside with respect to the bottom 15 of the vehicle tank 11. The heat distributor 4 thus separates the drying space 18 from the interior region 12 of the vehicle tank 11 filled with the reducing agent 14. A delivery module (not shown) for delivering the reducing agent 14 can be accommodated in the drying space 18.

The heat-conducting device 6 of the heat-distributing body 4 has a coupling element 8 which is arranged directly between the PTC heating element 3 and the heat-distributing body 4, and two differently sized thermally insulating layers 9b, 9c which are arranged in local regions on the surface of the heat-distributing body 4. One heat insulation layer 9b is arranged here on the surface of the heat distribution body 4 facing the interior 12 of the vehicle tank 11, and the other heat insulation layer 9c is arranged on the surface of the heat distribution body 4 facing the drying space 18.

The pot-shaped design of the heat distributor body 4 enables a large area of heat transfer and thus a large heat flow to the reducing agent 13 and thus further contributes to a reliable and rapid heating of the reducing agent 13.

The different features of the individual embodiments can also be combined with one another. The embodiments of fig. 1 and 2 are not particularly restrictive but serve to illustrate the inventive idea.