Cold start heating device for an internal combustion engine of a motor vehicle

Abstract

Cold start heating device (2) for an internal combustion engine of a motor vehicle, comprising a chamber (6) through which a fluid (14) flows, having a supply-side inlet area (16) and a discharge-side outlet area (18), wherein the chamber (6) is at least partially filled with a sorbent (8) in which a first heat exchanger (12) is embedded, wherein a fluid humidifier (22) is arranged in the inlet area (16) of the chamber (6), which in operation enriches the fluid (14) with a sorbate (20, 42) that can be sorbed by the sorbent (8), characterized in that a second heat exchanger (76) designed as an evaporator is provided in the inlet area (16) of the chamber (6), which has a heat exchange surface (74), and that the heat exchange surface (74) is designed as an evaporation element (82) of the fluid humidifier (22).

Description

The invention relates to a cold start heating device for an internal combustion engine of a motor vehicle, having a chamber through which a fluid can flow, having an inlet region on the feed side and an outlet region on the discharge side, wherein the chamber is at least partially filled with a sorbent in which a heat exchanger is embedded. The invention further relates to a motor vehicle having an internal combustion engine and a cold start heating device of this type for preheating the internal combustion engine.In an internal combustion engine, a cold start is referred to as an operating start in which engine fluids, such as, for example, a cooling water or a hydraulic / lubricating oil, have not been preheated and no operating pressure or sufficient oil reserves are provided in bearing points in a lubricating oil circuit. Such a cold start is a comparatively high load for the internal combustion engine, since increased wear occurs due to an uneven heating of the engine components. As a result, the internal combustion engine cannot be fully loaded during a cold start phase, so that it is desirable to achieve an optimum operating temperature as time-saving as possible.For example, DE 10 2013 014 238 A1 discloses an air conditioning system for a motor vehicle, in which at least some of a heat dissipated from a vehicle interior is transferred to an engine cooling circuit of the internal combustion engine, so that the latter reaches its intended operating temperature more quickly. As a result, the cold start phase is shortened, which has an advantageous effect both on the fuel consumption and on the emission behavior of the motor vehicle.Reducing fuel consumption and improving the emissions of motor vehicles is an important objective in the development of motor vehicles, and accordingly at present high effort is being expended in this regard.An alternative possibility for shortening the cold start phase is furthermore to use what is known as auxiliary heating and to couple the heat generated with it not directly into the passenger compartment, but indirectly via the coolant circuit of the internal combustion engine, as a result of which a certain preheating of the internal combustion engine likewise takes place.Furthermore, it is conceivable to use heat from the exhaust gases of the internal combustion engine in the cold start phase of the internal combustion engine in order to shorten the cold start phase and to achieve a more rapid heating to the intended operating temperature.Likewise, so-called open adsorption accumulators or adsorption systems could be used as cold start heating devices for the rapid heating of liquid engine fluids, in particular of lubricating oil in the internal combustion engine. Open adsorption accumulators of this type act in the manner of a thermochemical latent heat accumulator and are in exchange with the environment. This exchange typically takes place by means of a (carrier) fluid which flows around or through the adsorption store. The principle of heat storage is based here on a sorption process between a sorbent material (sorbent, sorbent, sorbent) and an depositing material (sorbate).When used as cold start heating devices, zeolites are typically used as sorbent, which are stored or arranged, for example, as a sorbent bed or a zeolite bed in a chamber. A particularly suitable sorbate in this context is water from an ambient air supplied. Embedded in the zeolite bed is a heat exchanger through which the engine fluid (engine oil, engine coolant) to be heated is conducted.During the cold start phase, the ambient air is guided as a fluid through the zeolite bed, wherein the ambient air is supplied in particular from the vehicle environment in front of the vehicle or from the engine compartment through which ambient air flows or, for example, from the passenger compartment or from the exhaust gas region. The water entrained in the air as atmospheric moisture is absorbed by the zeolite, with the result that an absorption heat is generated with which the engine fluid is heated in the heat exchanger.After the cold start phase, desorption of the water from the zeolite bed takes place automatically on account of the elevated operating temperature of the engine fluid within the heat exchanger. The desorbed water is again discharged from the chamber as air humidity via the air flow. In order to maintain the desorbed state until a cold start to be carried out again, the inlet and outlet regions of the chamber are typically closed off in an approximately fluid-tight manner by means of valves or flaps during this period.The power density and energy density and the performance dynamics of such cold start heaters are essentially dependent on the prevailing (relative) humidity at a given air temperature. Since in applications in the motor vehicle sector such cold start heating devices are designed for the typically comparatively low air humidity of the ambient air, the cold start heating devices have comparatively low usable heating energies and usable heating powers. As a result, it is necessary to dimension the cold start heating devices to be correspondingly larger, which has a disadvantageous effect on the production costs and the available installation space within a motor vehicle.DE 38 34 559 A1 describes a method for heating an intake air flowing through a line to an internal combustion engine, in which the intake air is branched off from the line upstream of an adjustable throttle element, a fluid is admixed with it and the mixture is conducted through a heating chamber and returned to the line downstream of the throttle element.DE 40 31 873 A1 discloses a heat storage plant having a reaction water circuit which passes through a zeolite bed and into which a heat exchanger is incorporated for releasing the reaction heat released in the zeolite and in the process generating a water vapor front.The invention is based on the object of specifying a cold start heating device for the internal combustion engine of a motor vehicle which is improved with regard to preheating of the internal combustion engine. In particular, an improvement of the usable heating power and the usable heating energy of an adsorption storage device is to be achieved. The invention is furthermore based on the object of specifying a motor vehicle having a cold start heating device of this type.With regard to the cold start heating device, the object mentioned is achieved according to the invention with the features of claim 1 and with regard to a motor vehicle having this cold start heating device with the features of claim 10. Advantageous embodiments and developments are the subject matter of the respective dependent claims.The cold start heating device according to the invention is suitable and configured for preheating an internal combustion engine of a motor vehicle, in particular during a cold start phase. The cold start heating device is designed as an (open) sorption system and in particular as an (open) adsorption system.For this purpose, the cold start heating device has an (adsorption) chamber through which a fluid can flow, which in an assembled state is connected by means of an inlet region to a (fluid) feed on the one hand and by means of an outlet region to a (fluid) discharge on the other hand. The chamber is at least partially filled with a sorbent in which a first heat exchanger is embedded. In the operating state, the first heat exchanger is in particular flowed through by an engine fluid of the internal combustion engine.In the (fluid) feed or in the inlet region of the chamber, a fluid humidifier is provided which, during operation, accumulates or releases the fluid flowing into the chamber with a sorbate that can be absorbed by the sorbent while generating an adsorption heat. The fluid moisture, i.e. in particular the relative proportion or the absolute concentration of sorbate in the fluid, is increased by the fluid humidifier during or before entry into the chamber, so that effectively more sorbate is available for the sorbent. This means that the fluid is artificially enriched with the sorbate or that the concentration of the sorbate is increased within the fluid flowing through the chamber. As a result, more sorbate is absorbed or absorbed during the sorption process, as a result of which an improved heat generation for heating the engine fluid guided within the first heat exchanger is generated.In other words, a significant increase and, if appropriate, an increase in the usable heating power and the usable heating energy is made possible by means of the fluid humidifier. This makes it possible to design the cold start heating device with a reduced dimensioning, which has an advantageous effect on the production costs and the required installation space in the motor vehicle.The fluid humidifier thus enables a significantly improved power and energy density for the cold start heating device designed as an adsorption plant in comparison with the prior art. This further improves the performance dynamics of the cold start heater. This means that in automotive applications with a minimum heating power or heating energy predetermined for different ambient conditions (air humidity, temperature), the overall size, the overall weight and the production costs are reduced.To preheat the internal combustion engine, heat is generated in the chamber by the sorption process, as a result of which the latent heat store or sorbent is virtually discharged and, during the subsequent operation of the internal combustion engine, the waste heat thereof is used in order to force a desorption process in the chamber, as a result of which the sorbent is recharged again. In this way, the fuel consumption and the emission characteristic of the internal combustion engine are advantageously influenced at the beginning of a startup. The fluid humidifier is preferably operated in particular during preheating, and is placed in a non-active idle state, for example, in the subsequent operation for desorption.The cold start heating device and in particular the chamber acting as sorption system is kept relatively simple and relatively compact, as a result of which the cold start heating device can be produced without cost-intensive and / or greater technical outlay, and as a result of which it is ensured that the cold start heating device has the smallest possible installation space requirement. This is of importance in particular because the number of additional units in a motor vehicle for implementing additional functions increases steadily and accordingly the available installation space for corresponding additional units decreases steadily.The chamber serves as a storage container for the sorbent and the sorbate, which is adsorbed or absorbed depending on the operating condition. A storage container containing the sorbent is often referred to in the prior art as a sorbent storage, sorbent container, adsorption storage or sorption bed or sorption bed housing and accordingly the chamber is preferably designed as such a sorption bed housing. The sorption bed is in particular a loose bed of the sorbent and is held in the chamber, for example, by means of a fine-mesh wire cage. Alternatively, for example, a sorbent forming element produced by pressing is also conceivable, or the sorbent is applied as a coating to a structure having a large surface area, in particular the first heat exchanger.The quantity of sorbent and / or the quantity of sorbate supplied in the cold start heating device is just predefined in such a way that as a result, a quantity of heat can be stored in the sorbent, by means of which the engine fluid of the internal combustion engine, in particular an engine oil and / or an engine coolant, can be heated. This means that the preheating of the internal combustion engine is preferably achieved by heating an engine fluid which circulates therein during operation of the internal combustion engine by means of the heat from the adsorption process. In this case, the amount of heat storable in the sorbent is selected such that the engine fluid and, in addition, preferably the structural elements in which the engine fluid is guided can be heated to a minimum temperature independently of the ambient temperature, at least provided it is in an expected temperature range.The heating of the engine fluid preferably takes place within a relatively short time interval, for which reason the cold start heating device is configured in a possible embodiment such that the engine fluid circulates in the internal combustion engine during the preheating, in the special case also without the internal combustion engine being started for this purpose. In this way, a more rapid, even distribution of heat throughout the engine fluid is achieved.The term sorbent is generally understood to mean a chemical reactant or an adsorbent material, but preferably a zeolite is used with or without a binder. In addition to good environmental compatibility, zeolites have the advantage that they can be produced comparatively inexpensively and that in these zeolites the sorption process is insensitive to position and vibration, which is advantageous in particular with regard to an application in the motor vehicle. Zeolite types 13X, Na-A, Mg-A, Ca-A, Na-X, Na-Y and H-Y are considered to be particularly suitable here, inter alia also since these show no decomposition phenomena even on frequent reactivation.The sorbate is expediently water, wherein, depending on the sorbent, further substances, such as, for example, a supplied gas, are also conceivable. The material purity of the water is of lower relevance here, wherein an antifreeze, such as salt or glycol, for example, may be added to the water.The fluid is preferably a supplied (ambient) air which supplies the sorbate, in particular the water, as air humidity to the chamber or discharges it therefrom.The air humidity of the supplied ambient air is thus enriched by the fluid or air humidifier (for example <30% relative) to a comparatively high humidity value. Preferably, a relative proportion of the sorbate or of the water of greater than 70% in the fluid is generated by the fluid humidifier, so that as a result a particularly effective heat generation takes place in the adsorption store.In a suitable development, the sorbate of the fluid humidifier exits from an evaporation element on the inner wall side when the fluid flows through or past. Additionally or alternatively, the sorbate of the fluid humidifier is distributed or released into the fluid flowing past by means of an atomizing device. As a result, the sorbate is supplied to the supplied fluid stream within the limited installation space of the fluid supply or of the inlet region of the chamber on a volume-specifically high evaporation or atomization surface. Thus, a particularly effective transfer of the sorbate into the supplied fluid stream is made possible, whereby the (relative) fluid humidity is particularly effectively increased.In a possible further development, the evaporation element is produced, for example, from a woven or felt-like material structure or equipped with a capillary coating. The capillary coating is formed, for example, by fine lamellae, a porous coating, in particular a metal powder coating, or a microstructured surface. As a result, on the one hand, the sorbate is incorporated in the coating due to capillary action, as a result of which the sorbate surface is likewise enlarged. On the other hand, the sorbate surface area thus enlarged ensures particularly simple entrainment of the sorbate by the fluid stream flowing past.The evaporation element is expediently arranged as a wall lining or wall coating within the inlet region.However, a development form is likewise also conceivable, for example, in which the evaporation element is mounted within the inlet region as a fluidically favourable installation, for example as a lamellar surface element.The atomizing device is designed, for example, as one or more injection nozzles which spray the sorbate into the fluid. Alternatively, the atomizing device can also be implemented as an ultrasonic element, for example in the form of a piezoelectric element. As a result, a sorbate aerosol can be generated in the inlet region, which aerosol is carried along and taken up by the flowing fluid in a particularly simple manner.It is essential that the evaporation element and / or the atomizing device provide an upper or transition surface as large as possible between the sorbate supplied and the fluid flowing past. This ensures that the highest possible proportion of sorbate is carried into the chamber.In an advantageous embodiment, the fluid humidifier is coupled to a preferably pressure-proof and frost-proof sorbate reservoir for the immediate temporary storage of the sorbate. The sorbate is preferably supplied to the evaporation element and / or the atomizing device of the fluid humidifier via a feed line through the sorbate reservoir.The sorbate reservoir preferably has a refilling device, for example in the form of a pressure-tight screw closure, so that sorbate losses, in particular with respect to the sorbate discharged through the fluid discharge, can be compensated. This reduces the service effort for manually refilling the sorbate.In an expedient embodiment, the sorbate is conveyed by means of a pump device, a capillary element or gravimetrically from the sorbate reservoir to the fluid humidifier. This ensures reliable supply of the sorbate to the fluid humidifier. In addition or as an alternative to the pump device, the capillary element or the gravimetric inlet, a valve arrangement is provided, for example, in the feed line between the sorbate reservoir and the fluid humidifier.The sorption process in the chamber is an equilibrium process between the sorbent and the sorbate. This equilibrium process can be influenced, for example, by changes in concentration, pressure or temperature. In a preferred embodiment, the pumping or conveying device is therefore coupled to a controller and / or a sensor element in the input region. The sensor element detects a fluid state of the supplied fluid and, as a function thereof, controls the pumping or conveying device (and / or the valve arrangement) in such a way that more or less sorbate is conveyed to the fluid humidifier.The sensor element is embodied here, for example, as a temperature sensor, a pressure sensor, a moisture sensor or as a combination thereof. The sensor element thus ensures that an optimum fluid moisture, that is to say an optimum concentration of the released sorbate in the fluid, is always generated for the chamber. In other words, a controlled metering of the sorbate is possible by the sensor element, in particular with respect to a saturation limit of the sorbate in the fluid and / or of the sorbate in the sorbent. This allows an improved power density limit of the cold start heating device without the sorbent bed becoming wet through, in particular due to a premature dew point drop below, within the chamber.The sensor element is preferably coupled to a controller, which actuates the pumping or conveying device as a function of the detected sensor signals. This realizes a particularly cost-effective integration solution for the controlled control of the pumping or conveying device or the metering.The controller is formed at least in the core by a microcontroller with a processor and a data memory, in which the functionality for carrying out the metering is implemented in a program-technical manner in the form of operating software (firmware), so that the method-possibly in interaction with a user-is carried out automatically in the microcontroller when the operating software is executed.In one possible embodiment, however, the controller is alternatively also formed by programmable electronic components, for example an application-specific integrated circuit (ASIC), in which the functionality for carrying out the metering is implemented by means of circuit technology.In one conceivable embodiment, a collecting device is arranged in the inlet region of the chamber, which collecting device feeds the sorbate, which precipitates or excess sorbate from the fluid, to the sorbate reservoir. The collecting device collects sorbate that is excess or not taken up or carried along by the fluid stream and introduces this into the sorbate reservoir by means of a return line. The collecting device thus realizes a return of the sorbate, whereby at the same time an accumulation of sorbate in the fluid supply is avoided. By means of the return, it is thus also possible to dispense with a sensor element, since in the event of fluid supersaturation with the sorbate, the excess sorbate precipitates out of the supersaturated fluid or is not entrained by the fluid, and is introduced into the sorbate reservoir.A further or additional aspect of the invention provides that, in order to improve the efficiency, a second heat exchanger through which a heat medium flows and to which the fluid is applied is integrated in the inlet region and / or in the outlet region of the chamber. In other words, a thermal connection of the cold start heating device is provided. The heat medium is here expediently an engine cooling water, an engine oil or a cooling or charge air. This means that the heat medium is preferably guided within a heat circuit of the internal combustion engine. In contrast to the engine fluid, the heat medium therefore does not always circulate within the internal combustion engine itself.By the arrangement of at least one additional, actively operated (second) heat exchanger, an evaporation of the sorbate in the inlet region or a condensation of the sorbate in the outlet region is improved. In this case, it is advantageous in terms of energy that the heat of evaporation required for evaporating the sorbate in the inlet region is supplied essentially via the external heat medium, or the condensation in the outlet region is promoted by the removal of condensation heat to the outside. As a result, the heat of vaporization is not only taken from the supplied fluid stream while simultaneously cooling it, or the heat of condensation is not dissipated into the discharged fluid stream while simultaneously heating it.The thermal connection makes it possible to both increase the absolute fluid humidity (fluid supply / inlet region) and decrease it (fluid discharge / outlet region), whereby the power density of the cold start heating device is increased.In a suitable embodiment, in particular a second heat exchanger, which is designed as a condenser and condenses the sorbate from the fluid, is provided in the outlet region of the chamber. The condensed sorbate is collected in a collecting region and in particular fed to the sorbate reservoir. As a result, sorbate recovery is realized, so that a substantially closed sorbate circuit of the cold start heating device is formed between the fluid humidifier and the sorbate reservoir and the condenser with the collecting region. In other words, it is possible for the sorbate emerging from the sorbent bed during the desorption phase to be at least partially recovered. As a result, the sorbate can be released again during a subsequent adsorption phase for increasing the performance by the fluid humidifier.In an equally advantageous refinement, the collecting region is integrated in a heat exchanger surface of the second heat exchanger. In a suitable further development, the second heat exchanger designed as a condenser has, for example, a number of cooling fins or fins through which the heat medium flows as a heat exchanger surface. The cooling fins can be arranged here, for example, on the inner wall of the outlet region, wherein the cooling fins are arranged in particular in a shell-like receptacle as a collecting region in which the condensed sorbate collects and drains away to the sorbate reservoir.In an embodiment according to the invention, in particular a second heat exchanger designed as an evaporator is provided in the inlet region of the chamber. The evaporator has a heat exchanger surface which is designed according to the invention as an evaporation element of the fluid humidifier. This means that the second heat exchanger is at least partially integrated into the fluid humidifier. This forms a functionally advantageous construction or assembly unit.The heat exchanger surface preferably has means for surface enlargement, such as evaporation elements, capillary surfaces or microstructures. Additionally or alternatively, the heat exchanger surface is charged with the sorbate from the atomizing device. This ensures particularly effective release or accumulation of the fluid with the sorbate.In the preferred application, the cold start heating device is installed in a motor vehicle for preheating the internal combustion engine. The cold start heating device is preferably coupled to the vehicle environment or to the engine compartment or to an air conditioning unit of the motor vehicle, from which air conditioning unit, for example, the fluid is supplied and / or discharged.The feed line supplying the sorbate for the purposes of fluid moistening or the associated sorbate reservoir is in this case preferably coupled directly or by means of a further sorbate reservoir to a collecting region of condensate of the air conditioning device. In other words, the condensate of the air conditioner is preferably used as sorbate for the cold start heating device and supplied thereto. This means that at least with regard to the sorbate, an exchange or a coupling is provided between the air conditioning device and the cold start heating device.The components (lines, reservoirs) carrying the sorbate are preferably arranged in a frost-proof region during operation of the motor vehicle, or are themselves designed to be frost-proof. This means that the risk of damage as a result of freezing of the sorbate is advantageously avoided. As a result, the cold start heating device can be integrated into an existing motor vehicle in an operationally suitable manner.Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. In the drawings, schematic and simplified representations show: FIG. 1 is a side view of a cold start heating device with a sorbent-filled chamber with an inlet region and an outlet region as well as with a heat exchanger embedded in the sorbent, and with a sorbate-releasing fluid humidifier, FIG. 2 a shows a schematic side view of a wall lining as evaporation element of the fluid humidifier, FIG. 2 bshows, in a representation according to FIG. 2 a, an evaporation element (built-in evaporation element) of the fluid humidifier, which is preferably installed on the wall side, FIG. 3 a shows a schematic side view of two injection nozzles as atomization device of the fluid humidifier, FIG. 3 bshows an ultrasonic element as atomization device of the fluid humidifier in a representation according to FIG. 3 a, FIGS. 4 a, 4 bin a representation according to FIGS. 2 and 3 a supply of the sorbate to the fluid humidifier from a sorbate reservoir, FIGS. 5 a, 5 bin a representation according to FIG. 4 a collecting device of the fluid humidifier, FIG. 6 shows, in a representation according to FIG. 5, a metering of the sorbate by means of a sensor element in the input region, FIG. 7 shows a schematic side view of a capacitor in the outlet region with a collecting region, FIG. 8 shows a schematic side view of a return from the collecting region to the sorbate reservoir, FIG. 9 shows, in a representation according to FIG. 8, a thermal connection of the cold start heating device in a first embodiment variant, and FIG. 10 shows a schematic side view of the thermal connection of the cold start heating device in a second embodiment variant.Parts and sizes corresponding to one another are always provided with the same reference numerals in all figures.FIG. 1 shows a basic structure of a cold start heating device 2 for preheating an internal combustion engine of a motor vehicle. During the preheating of the internal combustion engine, which can in principle also take place before the internal combustion engine is put into operation or else is started when the internal combustion engine is put into operation, an engine fluid 4 of the internal combustion engine is heated by means of the cold start heating device 2. As a result, the so-called cold start phase is reduced and the emission behavior of the motor vehicle is improved. The engine fluid 4 is, for example, an engine lubricant or an engine coolant which circulates at least in sections within the internal combustion engine or its components.The cold start heating device 2 has a chamber 6, which is designed as an adsorption plant and serves as a thermochemical latent heat store. A loose bed of a sorbent 8, in particular of a zeolite, is stored in the chamber 6, forming a sorption bed. The zeolite 8 is held by means of a fine-mesh wire cage 10. A heat exchanger 12 carrying the engine fluid 4 is arranged or embedded in the zeolite 8.During operation, a fluid 14, in particular (ambient) air, flows through the chamber 6. For this purpose, the cold start heating device 2 is connected to an air circuit, not shown in detail, or an air duct of the motor vehicle, which conducts the air 14 into the chamber 6 via a feed-side inlet region 16 and leads it out of the chamber 6 via a discharge-side outlet region 18. The air 14 has a certain degree of humidity, that is to say a certain humidity, with a comparatively low (relative) proportion of a sorbate 20, in particular water.During the cold start phase, the air 14 is passed through the zeolite 8. The water 20 carried along as atmospheric moisture is absorbed by the zeolite 8, with the result that an absorption heat is generated with which the engine fluid 4 is heated within the heat exchanger 12. The performance dynamics of the adsorption process or the heat generated thereby are dependent here on the (relative) proportion of the water 20 in the air 14 and on the total surface area of the steam- or mist-like water-air mixture. To improve the performance dynamics, a fluid or air humidifier 22 is therefore provided in the inlet region or the feed 16, which releases water 20 continuously or at regular time intervals to enrich the air 14 or to increase the air humidity. The relative proportion of the water 20 in the supplied air 14 is increased by the humidifier 22, for example, to >70%.With reference to FIGS. 2 a, 2 b, 3 aand 3 b, various exemplary embodiments of the inlet-side humidifier 22 are explained in more detail below.In the exemplary embodiment of FIG. 2 a, the humidifier 22 has a wall evaporation element 24, which is installed as an approximately hollow cylindrical inner wall lining inside the feed 16. The wall evaporation element 24 has a surface wetted by the water 20. To increase the surface area, and thus to improve the release of the water 20 into the air 14 flowing past, the wall evaporation element 24 has a ribbing or a ventilation 26. The ribbing or ventilation 26 is provided, for example, with a gap-like geometry, so that the water 20 is drawn into the ribbing or ventilation 26 by capillary action.In an alternative exemplary embodiment, the surface facing the air 14 or the surface wetted by the water 20 is provided with a porous coating 28, for example a metal powder coating, so that the water 20 is embedded in the coating 28 by means of capillary action, whereby the surface is likewise enlarged.In FIG. 2 b, the humidifier 22 is embodied by means of an installed evaporation element 30. The built-in evaporation element 30 is here designed with particular favourable flow properties with respect to the air flow flowing past as segmented, lamellar surface elements 32, on which the water 20 evaporates. The surface elements 32 are arranged in the manner of a circular ring on the inner wall of the feed 16 and are provided with reference numerals merely by way of example. The surface elements 32 have substantially similar surfaces, ribbings or creases 26 and / or coatings 28 to the wall evaporation element 24.FIGS. 3 aand 3 b show an air humidifier 22 with a atomizing device 34 which mixes the water 20 in a gaseous, in particular vapor- or mist-like, state into the air stream flowing past.In Figure 3a, the atomizing device 34 is formed by a pair of injection nozzles 36 which inject the water 20 as a fine mist into the air 14.The exemplary embodiment of FIG. 3 bshows an atomizing device 34 having a water bath 38 and an ultrasonic element 40 countersunk therein. the ultrasonic element 40, which is embodied as a piezoelectric element, for example, generates oscillations in the ultrasonic range during operation, as a result of which a fine-lived aerosol 42 exits at the water surface of the water bath 38. The air stream carries the evaporating fine aerosol particles 42 with it the air 14 and passes them to the zeolite 8.In the following, the water supply or water supply 44 of the humidifier 22 is described in more detail with reference to FIGS. 4 aand 4 b. The water supply 44 has a sorbate or water reservoir 46 as a closed container, in which the water 20 is stored at least temporarily. The water 20 is supplied by means of a pump device 48 from the reservoir 46 by means of a supply line 50 to the releasing elements of the humidifier 22.In the exemplary embodiment of FIG. 4 a, the water 20 is conveyed by means of a pump device 48 designed as a suction pump. In the exemplary embodiment of FIG. 4 b, the pump device 48 is designed in particular as a pressure pump, wherein in this embodiment the interior of the container of the reservoir 46 is preferably prestressed or acted upon by a gas pressure, in particular by means of compressed air.FIGS. 5 aand 5 b show a collecting device 52 of the humidifier 22 for collecting the precipitating water 20 in the region of the humidifier 22. In these exemplary embodiments, the humidifier 22 is designed by means of built-in evaporation elements 54, which are connected to the supply line 50 of the water supply 44. The evaporation elements 54 are designed functionally similar to the wall evaporation element 24 and the built-in evaporation element 30 in terms of their surface nature and configuration.The collecting device 52 is expediently arranged below the evaporation elements 54 and collects water 20 dripping down from the evaporation elements 54 on the one hand and water 20 not carried along by the air flow or not evaporated or precipitating on the other hand. The excess water 20 is collected and introduced into the reservoir 46 by means of a return line 56. In FIG. 5 a, the collecting device 54 is designed as a collecting tray arranged inside the feed 16. The exemplary embodiment of FIG. 5 bshows a collecting device 52, which is integrated in the feed 16 in a fluidically favorable manner as a trough-like depression.With reference to FIG. 6, a controlled control of the pump device 48 is explained. For this purpose, the pump device 48 is connected to a controller 58 by signal technology. The controller 58 is in turn coupled by signal lines 60 to a sensor element 62. The sensor element 62 is mounted in the feed 16 and is arranged fluidically behind the humidifier 22, that is to say in particular between the humidifier 22 and the chamber 6. The sensor element 62 is embodied, for example, as a temperature sensor, a pressure sensor, a humidity sensor or as a combination thereof.Depending on the detected sensor signals, more or less water 20 is conveyed from the pump device 48 to the humidifier 22. By means of the metering provided in this way, an optimum or a favorably approximated equilibrium can be set during the adsorption process in the chamber 6, so that a particularly effective heat generation during the cold start phase for preheating the internal combustion engine is ensured even at different ambient temperatures and / or humidities.After the cold start phase, desorption of the water 20 from the zeolite bed takes place automatically on account of the elevated operating temperature of the engine fluid 4 within the heat exchanger 12, the desorbed water 20 being discharged here again as atmospheric humidity via the air stream from the chamber 6 via the outlet region or the outlet 18.In order to at least partially recover the desorbed water 20, a recovery 64 is preferably provided in the outlet 18, which recovery recovers the water 20 from the air stream and supplies it to the water supply 44. As a result, a substantially closed water circuit is realized within the cold start heating device 2, so that no significant water losses occur. In order to possibly compensate for water losses, the reservoir 46 preferably has a pressure-proof screw cap, not shown in detail, as a manual refilling device.Exemplary embodiments for a thermal connection of the feed 16 and / or the discharge 18 to a heat circuit of the internal combustion engine are shown below with reference to FIGS. 7, 8, 9 to 10.FIG. 7 shows the discharge 18 with a heat exchanger 66 designed as a condenser and a collecting region 68 arranged underneath as part of the recovery 64. as is shown for example in FIG. 8, the collecting region 68 is connected to the reservoir 46 by means of a return line 70. The collecting region 68 serves in particular for collecting the water 20 condensing on the condenser 66, and it is thus possible by the condenser 66 for the water 20 emerging from the zeolite 8 during the desorption phase to be at least partially recovered.A heat medium 72 of the internal combustion engine preferably flows through the condenser 66. The heat medium 72 is, for example, an engine cooling water, an engine oil, or a cooling or charge air. In contrast to the engine fluid 4, the heat medium 72 thus does not circulate through the internal combustion engine itself, but preferably within a heat circuit of the internal combustion engine.A particularly effective arrangement in terms of energy is realized by the condenser 66, since the condensation in the discharge 18 is promoted by the removal of condensation heat to the outside. In other words, instead of being discharged into the discharged air 14, the condensation heat is discharged into the heating medium 72 while simultaneously heating it.FIGS. 9 and 10 show exemplary embodiments of the cold start heating device 2, in which both the supply 16 and the discharge 18 have a thermal connection to the heat circuit of the internal combustion engine.FIG. 9 shows an air humidifier 22 with the wall evaporation element 24 in the feed line 16, which are fed from the feed line 50 of the water feed line 44. On the outside, in the region of the wall evaporation element 24, a heat exchanger surface 74 of a heat exchanger 76 designed as an evaporator, enclosing the feed 16, is arranged. The heat exchanger surface 74 can also be integrated into the inner wall of the feed 16. The heat medium 72 flows through the evaporator 76 in such a way that the vaporization heat required in the supply 16 is supplied essentially via the external heat medium 72.The evaporator 76 thus has a supporting effect for releasing the water 20 into the air 14, since the heat of evaporation is not only taken from the supplied air stream, with the simultaneous cooling thereof. In this exemplary embodiment, the heat exchanger 76 and the wall evaporation element 24 preferably form a common construction or assembly unit, that is to say that the evaporator 76 is at least partially integrated into the humidifier 22.The condenser 66 in the discharge 18 is designed in the example of FIG. 9 substantially similar to the corresponding evaporator 76 of the feed 16. The heat exchanger surface 78 of the condenser 66 additionally has lamellar cooling ribs 80 which project in a fluidically favorable manner into the flow path of the discharged air 14. The cooling ribs 80 are here at least partially integrated into the dish-like collecting region 68.The exemplary embodiment illustrated in FIG. 10 shows a further embodiment of the integrated heat exchangers 66 and 76 in the feed 16 and in the discharge 18, respectively. In this embodiment, the humidifier 22 has two injection nozzles 36 which inject the water 20 in the direction of the evaporator 76. In this embodiment, the evaporator 76 is provided with porous or capillary-coated lamellae 82, the surfaces of which are embodied, for example, with the ribbing or ventilation 26 and / or the coating 28. The fins 82 are sprayed or wetted with the water 20 of the injection nozzles 36 during operation, wherein the water is subsequently released into the air stream, assisted by the evaporator 76.In this exemplary embodiment, the condenser 66 is designed as a helical tube or helical tube heat exchanger, the air-side surface of which is likewise provided with the ribbing or ventilation 26 and / or the coating 28. The collecting region 68 is introduced as a collecting channel-like depression into the side wall of the discharge 18. The collecting region 68 has an opening for the return line 70 at a lowest point, so that the condensing water 20 is collected and recirculated without any problem.The invention is not limited to the above-described embodiments. Rather, other variants of the invention can also be derived from this by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiments can also be combined with one another in another manner without departing from the subject matter of the invention.

Claims

Cold start heating device (2) for an internal combustion engine of a motor vehicle, having a chamber (6) through which a fluid (14) can flow, having an inlet region (16) on the feed side and an outlet region (18) on the discharge side, wherein the chamber (6) is at least partially filled with a sorbent (8) in which a first heat exchanger (12) is embedded, wherein a fluid humidifier (22) is arranged in the inlet region (16) of the chamber (6), which enriches the fluid (14) with a sorbate (20, 42) that can be absorbed by the sorbent (8) during operation, characterized - in that a second heat exchanger (76), which is designed as an evaporator and has a heat exchanger surface (74), is provided in the inlet region (16) of the chamber (6), and - in that the heat exchanger surface (74) is designed as an evaporation element (82) of the fluid humidifier (22).Cold start heating device (2) according to claim 1, characterised in that the sorbate (20, 42) of the fluid humidifier (22) exits from an evaporation element (24, 30, 32, 54, 82) on the inner wall side when the fluid (14) flows through and / or is distributed into the fluid (20) by means of an atomising device (34, 36, 40).Cold start heating device (2) according to claim 1 or 2, characterised in that the fluid humidifier (22) is coupled to a sorbate reservoir (46).Cold start heating device (2) according to claim 3, characterised in that the sorbate (20) is conveyed from the sorbate reservoir (46) to the fluid humidifier (22) by means of a pump device (48).Cold start heating device (2) according to claim 4, characterised in that the pump device (48) is in signal communication with the fluid humidifier (22) with a controller (58) and / or with a sensor element (62).Cold start heating device (2) according to one of claims 3 to 5, characterised in that a collecting device (52) is arranged in the inlet region (16) of the chamber (6), which collecting device feeds sorbate (20), which precipitates or is excess from the fluid (14), to the sorbate reservoir (46).Cold start heating device (2) according to one of claims 1 to 6, characterised in that a second heat exchanger (66, 76) through which a heat medium (72) flows is integrated in the outlet region (18) of the chamber (6).Cold start heating device (2) according to one of claims 1 to 7, characterised in that - a second heat exchanger (66) designed as a condenser is provided in the outlet region (18) of the chamber (6), which second heat exchanger condenses the sorbate (20) from the fluid (14), and - a collecting region (68) for the condensed sorbate (20) is provided, which second heat exchanger feeds the sorbate (20) in particular to the sorbate reservoir (46).Cold start heating device (2) according to claim 8, characterised in that the collecting region (68) is integrated into a heat exchanger surface (78, 80) of the second heat exchanger (66).Motor vehicle comprising an internal combustion engine and a cold start heating device (2) for preheating the internal combustion engine according to one of Claims 1 to 9.

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