Air-conditioning system and method for dehumidifying an air-conditioning system

Abstract

An air-conditioning system (10), in particular for the climate control of an interior of a motor vehicle, is provided, having a fan (14) for conveying drawn-in air through an air duct (16) and having an evaporator (12), provided in the air duct (16), for cooling the drawn-in air, wherein a collecting body (20), separate from the air duct (16), for collecting air humidity (18), condensed at the evaporator (12), of the drawn-in air is provided in the air duct (16), wherein, in the deactivated state of the evaporator (12), the drawn-in air is able to flow against and / or around the collecting body (20). As a result of the collecting body (20) being positioned within the air duct (16), it is possible to improve discharging of condensate (18) that arises at the evaporator (12), such that easy and efficient dehumidification of an air-conditioning system (10) is made possible.

Description

[0001] Air conditioning system and method for dehumidifying an air conditioning system

[0002] The invention relates to an air conditioning system with which the interior of a motor vehicle can be air-conditioned, as well as to a method with which such an air conditioning system can be dehumidified.

[0003] From DE 10 2005 022 208 A1 it is known to let a fan of an air conditioning system of the motor vehicle continue to run after a motor vehicle has been switched off and to guide the air flow of the fan along a lowest point of an air duct of the air conditioning system in order to be able to remove condensate water accumulating there from an evaporator of the air conditioning system.

[0004] There is a constant need to make dehumidifying an air conditioning system simple and efficient.

[0005] The object of the invention is to show measures that enable simple and efficient dehumidification of an air conditioning system.

[0006] The object is achieved according to the invention by an air conditioning system having the features of claim 1 and a method having the features of claim 9. Preferred embodiments of the invention are specified in the subclaims and the following description, which may each individually or in combination represent an aspect of the invention.

[0007] One aspect of the invention relates to an air conditioning system, in particular for air conditioning the interior of a motor vehicle, comprising a fan for conveying sucked-in air through an air duct and an evaporator provided in the air duct for cooling the sucked-in air, wherein a collecting body, different from the air duct, is provided in the air duct for collecting humidity of the sucked-in air condensing on the evaporator, wherein the sucked-in air can flow against and / or around the collecting body when the evaporator is deactivated. The fan can suck in air from the environment, wherein the sucked-in air can be warm or humid depending on the ambient conditions. This leads to humidity from the sucked-in air, which has been cooled by the evaporator, condensing on the cold evaporator. This condensate can drip off the evaporator under the influence of gravity.The dripping condensate can be collected and stored, at least temporarily, by the collector body. This prevents condensate from accumulating at the lowest point of the air duct. This design takes advantage of the fact that condensate collecting at the lowest point of the air duct typically forms a very small surface area, meaning that only a small mass flow of condensate can be removed by the air flow provided by the fan's after-run. Furthermore, the air duct is typically designed to minimize flow resistance, resulting in rather unfavorable flow conditions for condensate absorption at the duct wall.

[0008] With the aid of the collecting body, which is separate from the air duct, the condensate can be collected at a distance from the air duct wall, allowing the condensate to flow under more favorable flow conditions. The collecting body can be positioned adjacent to the evaporator. Preferably, the collecting body is spaced apart from the evaporator so that the condensate can drip from the evaporator via a thermally insulating air gap between the evaporator and the collecting body and impinge on the collecting body. Particularly preferably, the collecting body can be designed to distribute the condensate over a larger surface area than would be the case with a part-circular channel.The collecting body thus enables the collected condensate to come into contact with the airflow generated by the fan over a significantly larger surface area and under significantly better flow conditions, resulting in a significantly increased mass flow into the airflow and a greater loading of the airflow with the collected condensate. This in turn enables the air conditioning system, in particular the air duct, to dry more quickly and with less power from the fan. The energy efficiency of the air conditioning system for dehumidification is thereby improved. Since only a suitably designed and shaped collecting body needs to be positioned in a location that is easily accessible to or around the drawn-in air, in particular below the evaporator, this energy saving can be achieved structurally very easily.For example, the collecting body can be easily replaceable and inserted into a holder extending into the interior of the air duct, allowing air to flow around the collecting body on a variety of surfaces. Positioning the collecting body within the air duct can improve the removal of condensate produced on the evaporator, enabling simple and efficient dehumidification of an air conditioning system.

[0009] The air conditioning system can, in particular, have a closed cooling circuit in which the evaporator is provided. The cooling circuit can have a compressor for circulating a refrigerant in the cooling circuit. The refrigerant compressed by the compressor can be cooled in a heat exchanger or cooler, in particular a front radiator of the motor vehicle, and subsequently fed to the evaporator via an expansion valve. The evaporated refrigerant can then be fed back to the compressor and liquefied. The fan can guide the sucked-in air along surfaces of the evaporator, thereby cooling the sucked-in air. The cooled air can then be directed into the interior of the motor vehicle.

[0010] The air duct can lead from an inlet communicating with the environment via the fan to at least one outlet. In this case, an outlet leading to the interior of the motor vehicle can be provided in order to air-condition the interior using the conditioned air. The air duct can also lead to a further outlet communicating with the environment in order to discharge unused air and remove condensate carried along by the intake air, thereby dehumidifying the air conditioning system. Switching elements are preferably provided with the aid of which the mass flow and / or the flow direction of the air flow directed into the interior can be adjusted. In particular, it can be provided to direct the air flow drawn in by the fan over different flow paths with the aid of the at least one switching element. In particular, the collecting body has a plurality of storage pores for temporarily storing the condensing air humidity.The collecting body can be irregularly shaped to form the storage pores and can deviate significantly from the shape of a bowl. This allows the collected condensate to be distributed across the numerous pores. Due to the surface tension of the condensate, the water absorbed in the respective pore can be retained within the pore, preventing the condensate from dripping to the bottom of the air duct. At the same time, a large total surface area for the collected condensate can be formed across the pores, which improves the phase transition from the pore into the airflow generated by the fan and enables a high condensate loading of the airflow.

[0011] The collecting body is preferably designed as a sponge and / or foam. The collecting body can be made of a natural and / or synthetic material. For example, the collecting body is designed as an aluminum foam. The collecting body can thus easily form a multitude of pores and / or provide a large surface area for the collected condensate.

[0012] Particularly preferably, the collecting body is capable of being subjected to the intake of air flow at a bottom side facing downwards in the direction of gravity and / or at a top side facing downwards in the direction of gravity and / or at at least one side surface facing substantially horizontally. The collecting body can, in particular, be positioned substantially centrally within a flow cross-section of the air flow provided by the fan. Since the collecting body is preferably not only subjected to air flow on one side, but can even be surrounded by air flow on surfaces facing away from one another, a particularly large mass flow of condensate can be transferred from the collecting body to the air flow.

[0013] In particular, the fan is coupled to the evaporator via a timer relay with a predetermined delay time, so that the fan starts with a delay beyond the delay time after the evaporator is deactivated. This prevents the fan from continuing to run actively beyond the fan coasting to a stop. Instead, the delay time can be used to wait until the evaporator surfaces approach the ambient temperature sufficiently so that no significant condensate production on the evaporator surfaces is to be feared when the fan draws in unconditioned air. The condensate can be retained in the collecting body for the length of the delay time. The operating time of the fan after the delay time has elapsed, which is required to dehumidify the air conditioning system, can thus be minimized, so that the associated energy consumption can also be minimized.

[0014] Preferably, the fan can be switched off depending on the water load of the collecting body and / or after a predetermined drying time has elapsed. The fan can, for example, be operated until a humidity sensor indicates a sufficiently low condensate load in the collecting body, thus signaling sufficient dehumidification of the air conditioning system. The fan can thus be switched off in response to a measurement signal from the humidity sensor. Additionally or alternatively, the fan can wait for the predetermined drying time to elapse before switching off the fan. In particular, if the desired drying of the collecting body, as measured by the humidity sensor, cannot be achieved within the drying time during particularly warm and humid weather conditions, this can prevent unnecessarily long and inefficient operation of the fan.

[0015] Particularly preferably, the collecting body is arranged in a bypass duct that can be closed off from the rest of the air duct. This allows the air drawn in by the fan to flow around the evaporator during regular air conditioning operation, but not the collecting body. This can prevent the air directed to the interior of the motor vehicle from becoming undesirably enriched with moisture. When the evaporator of the air conditioning system and / or the motor vehicle are switched off, the air drawn in by the fan can be directed into the bypass duct, with the drawn-in air preferably being directed past the evaporator, which may still be quite cold. During this dehumidification mode of the air conditioning system, an outlet leading to the interior can be closed so that the particularly humid air, after flowing around the collecting body, can be discharged past the interior and into the environment.

[0016] In particular, the collecting body is positioned at a distance from a duct wall of the air duct. This prevents contact of the condensate with a duct wall, thus preventing wear effects caused by the presence of water, such as water corrosion on metal components. Furthermore, the intake air can flow around the collecting body over as large an area as possible.

[0017] A further aspect of the invention relates to a method for operating an air conditioning system, which can be designed and developed as described above, in which, after deactivation of the evaporator, in particular after switching off the motor vehicle, the fan is operated to dry the collecting body laden with condensing air humidity using the air sucked in by the fan and to discharge the condensing air humidity from the air conditioning system. The method can be designed and developed in particular as described above with reference to the air conditioning system. The collecting body positioned within the air duct can improve the discharge of condensate forming on the evaporator, thus enabling simple and efficient dehumidification of an air conditioning system.

[0018] Preferably, the fan is started after a predetermined delay time following deactivation of the evaporator and / or switching off the motor vehicle. This prevents the fan from continuing to run actively beyond coasting to a stop. Instead, the delay time can be used to wait for the evaporator surfaces to approach the ambient temperature sufficiently so that no significant condensate production on the evaporator surfaces is to be feared when the fan draws in unconditioned air. The condensate can be retained in the collecting body over the length of the delay time. The operating time of the fan after the delay time has elapsed, which is required to dehumidify the air conditioning system, can thus be minimized, so that the associated energy consumption can also be minimized.

[0019] The invention will be explained below by way of example with reference to the accompanying drawings using a preferred embodiment, wherein the features presented below can represent an aspect of the invention both individually and in combination. It shows:

[0020] Fig. 1 : a schematic sectional view of part of an air conditioning system.

[0021] The air conditioning system 10, only partially shown in Fig. 1, can be used to air-condition the interior of a motor vehicle. The air conditioning system 10 has an evaporator 12 in which a refrigerant can be evaporated to generate cold. As a result, an air flow drawn in from the environment by a fan 14 via an air duct 16 during regular air conditioning operation of the air conditioning system 10 can be cooled before the air flow reaches the interior of the motor vehicle. Condensate 18 forming on the evaporator 12 can drip down the surfaces of the evaporator 12 due to gravity and impinge on a collecting body 20, which is designed, for example, as a sponge or metal foam. The collecting body 20 can collect the condensate 18 and store it at least temporarily, in particular in pores of the collecting body 20.The collecting body 20 is positioned by means of holders 22 at a distance from a channel wall 24 of a bypass channel 26 connected to the remaining air channel 16 and is positioned substantially centrally to a flow cross-section of the bypass channel 26 of the air channel 16.

[0022] If the motor vehicle and / or the evaporator 12 is switched off and deactivated, the fan 14 can be switched on again after a delay time, which can be specified using a timer relay 28. During the delay time, the bypass channel 26 can be opened, for example with the help of at least one switching flap 30 of a switching element, and preferably a large part of the evaporator 12 can be blocked from the air flow. In this dehumidification mode, the air flow can flow around the collecting body 20 over as large an area as possible in order to collect as much condensate 18 as possible from the collecting body 20 and discharge it into the environment. The fan 14 can be switched off automatically after a specified drying time and / or when the humidity or water load of the collecting body 20 is sufficiently low, which can be measured using a humidity sensor 32.

Claims

Air conditioning system (10), in particular for air conditioning the interior of a motor vehicle, with a fan (14) for conveying sucked-in air through an air duct (16) and an evaporator (12) provided in the air duct (16) for cooling the sucked-in air, characterized in that a collecting body (20) different from the air duct (16) is provided in the air duct (16) for collecting air humidity (18) of the sucked-in air condensing on the evaporator (12), wherein the sucked-in air can flow against and / or around the collecting body (20) when the evaporator (12) is deactivated. Air conditioning system (10) according to claim 1, wherein the collecting body (20) has a plurality of storage pores for temporarily storing the condensing air humidity (18). Air conditioning system (10) according to claim 1 or 2, wherein the collecting body (20) is designed as a sponge and / or foam.The air conditioning system (10) according to one of claims 1 to 3, wherein the collecting body (20) can be flowed against by the sucked-in air at a bottom side facing downwards in the direction of gravity and / or at a top side facing downwards in the direction of gravity and / or at at least one side surface facing substantially horizontally. The air conditioning system (10) according to one of claims 1 to 4, wherein the fan (14) is coupled to the evaporator (12) via a timer relay (28) with a predetermined delay time such that the fan (14) starts with a delay beyond the delay time after deactivation of the evaporator (12). The air conditioning system (10) according to claim 5, wherein the fan (14) can be switched off depending on the water load of the collecting body (20) and / or after a predetermined drying time has elapsed. The air conditioning system (10) according to one of claims 1 to 6, wherein the collecting body (20) is arranged in a bypass channel (26) that can be closed from the remaining air channel (16). The air conditioning system (10) according to one of claims 1 to 7, wherein the collecting body (20) is positioned at a distance from a channel wall (24) of the air channel (16). Method for operating an air conditioning system (10) according to one of claims 1 to 8, in which, after deactivation of the evaporator (12), in particular after switching off the motor vehicle, the fan (14) is operated in order to dry the collecting body (20) loaded with condensing air humidity (18) with the aid of the air sucked in by the fan (14) and to discharge the condensing air humidity (18) from the air conditioning system (10).Method according to claim 9, wherein the starting of the fan (14) is carried out after a predetermined delay time from the deactivation of the evaporator (12) and / or from the switching off of the motor vehicle.

Images