DE102012008211A1 - Air conditioning apparatus for motor car, has controllable fan that is provided to control moderate temperature airflow through vaporizer and cold storage device - Google Patents

Abstract

The invention relates to an air conditioning system for a motor vehicle, comprising - an evaporator (30) permeable by refrigerant and by tempering air (40) and - a cold accumulator (60) through which at least the temperature control air (40) flows, whose cold accumulation medium is a PCM material ( 64), and - a controllable fan (50), by means of which the tempering air flow (40) through the evaporator (30) and the cold storage (60) is controllable. The invention is characterized in that the cold storage medium (60) through which the refrigerant does not flow is arranged downstream of the evaporator (30). The invention further relates to a control method for such a motor vehicle air conditioning system.

Description

• – einen von Kältemittel sowie von Temperierluft durchströmbaren Verdampfer und
• – einen wenigstens von der Temperierluft durchströmbaren Kältespeicher, dessen Kältespeichermedium ein PCM-Material enthält, und
• – ein steuerbares Gebläse, mittels dessen der Temperierluftstrom durch den Wärmetauscher und den Kältespeicher steuerbar ist.

The invention relates to an air conditioning system for a motor vehicle, comprising

• - A permeable by refrigerant and tempering air evaporator and
• - An at least by the tempering air flow-through cold storage, the cold storage medium contains a PCM material, and
• - A controllable fan, by means of which the tempering air flow through the heat exchanger and the cold storage is controllable.

• – einen von Kältemittel sowie von Temperierluft durchströmbaren Wärmetauscher und
• – einen wenigstens von der Temperierluft durchströmbaren Kältespeicher, dessen Kältespeichermedium ein PCM-Material enthält,

wobei zur schnellen Abkühlung eines Fahrzeuginnenraums von einer höheren Starttemperatur auf eine niedrigere Zieltemperatur der Wärmetauscher gleichzeitig von kaltem Kältemittel und der Temperierluft und der Kältespeicher wenigstens von der Temperierluft durchströmt und die Temperierluft in den Fahrzeuginnenraum ausgeblasen wird.The invention further relates to a method for controlling a motor vehicle air conditioner, comprising

• - A permeable by refrigerant and tempering heat exchanger and
• A cold storage medium through which at least the tempering air can flow, the cold storage medium of which contains a PCM material,

wherein for rapid cooling of a vehicle interior from a higher start temperature to a lower target temperature of the heat exchanger simultaneously flows through cold refrigerant and the tempering air and the cold storage at least by the tempering and the tempering is blown into the vehicle interior.

Such air conditioning systems and control methods are known from DE 10 2006 028 017 A1 ,

Automotive air conditioning systems regularly have a refrigerant circuit comprising an air conditioning compressor, a compressor side heat exchanger, an expansion device, and an evaporator to which cold refrigerant is supplied when the air conditioning compressor is operated. The evaporator is flowed through by tempering air. As a result, serving as a refrigerant medium tempering air is cooled and blown into the vehicle interior. Typically, the tempering on its way from the evaporator to the vehicle interior still passes through a counterheating heat exchanger, with which the temperature control can be adjusted to the desired outlet temperature. The tempering air flow is driven by a controllable fan, with which the strength of the Temperierluftstroms is adjustable.

For reasons of saving energy, modern motor vehicles have a so-called start / stop system, in which the internal combustion engine is switched off during standstill phases of the motor vehicle, for example when standing at traffic lights. The problem is that when the internal combustion engine typically mechanically driven by this air compressor is also available. As a result, the tempering air flowing into the vehicle interior is no longer dehumidified and cooled, so that, especially in warm weather, there is a very rapid increase in the temperature and humidity in the vehicle interior. To overcome this disadvantage, the DE 10 2006 028 017 A1 prior to combining the evaporator with a cold storage, which is pre-cooled during operation of the air conditioning compressor simultaneously with the cooling of the tempering through the cold refrigerant, ie "charged" and temporarily stores the cold due to its high heat capacity. In a malfunction of the provision of cold refrigerant, z. B. when the internal combustion engine and consequently stationary air compressor, the maintained tempering air flow is further cooled by the combined evaporator / cold storage and dehumidified. The cooling and dehumidification of the vehicle interior thus continues to work until the cold storage is "discharged". This duration is long enough, with appropriate design of the cold storage, to bridge engine stop phases of the automatic start / stop system. As a cold storage medium so-called PCM materials (PCM: Phase Change Material) have proven. These materials exhibit in the relevant temperature range, which is typically between 4 ° C and 10 ° C, a phase transition, which - depending on the transition direction - is associated with the release or binding of a significant phase transition energy. In the cited document, it is proposed, in particular, to conduct liquid refrigerant and liquid cold storage medium together in double-walled tubes of the combined evaporator / cold storage, wherein the refrigerant flows in the inner and the cold storage medium in the outer tube region.

The disadvantage here is that the so-called "cool-down", d. H. the rapid cooling of the vehicle interior, which offers a considerable comfort advantage, for example, when starting a heavily heated by stopping in the sun vehicle, is hampered. In particular, the temperature control air in the combined evaporator / cold storage is cooled by the refrigerant only indirectly via the cold storage medium, so that the cold used for loading the cold storage is not available for cooling the Temperierluftstroms available. To solve this problem, the cited document proposes to combine only a part of the evaporator with a cold storage, so that at least part of the heat exchanger is available in the cool-down case, in which a direct cooling of the Temperierluftstroms. Nevertheless, the known solution must be regarded as technically complex, because constructively complicated and requires, in order to achieve a really efficient rapid cooling, a comparatively large design of the air conditioning compressor, which is energetically disadvantageous.

It is the object of the present invention to provide a motor vehicle air conditioning system and a control method therefor, which, with a simplified design, allow both effective bridging of air compressor compressor downtime and efficient rapid cooling.

This object is achieved in conjunction with the features of the preamble of claim 1, characterized in that the non-flowed through the refrigerant cold storage is arranged downstream of the evaporator.

The object is further achieved in conjunction with the features of the preamble of claim 6, characterized in that the tempering air flow passing through the evaporator is set so strong until the target temperature of the vehicle interior is reached for the first time that the temperature of the tempering air in the region of the cold accumulator arranged downstream of the evaporator Phase transition temperature of the cold storage medium does not fall below.

Preferred embodiments of the invention are the subject of the dependent claims.

Central requirement for the effectiveness of the invention is first the functional and spatial separation between the cold storage and the evaporator. This ensures that the Temperierluftstrom can be cooled directly in the evaporator of the refrigerant. The refrigerant is in particular no cold deprived by the loading of the cold storage. Rather, it is completely available for cooling the tempering air. However, some heat coupling of the cold accumulator to the evaporator is maintained, namely via the tempering air flow, with respect to which the cold accumulator is arranged downstream of the evaporator. In other words, the cooling air cooled in the evaporator flows through the downstream cold storage, in order to be subsequently blown into the vehicle interior.

This is where the inventive control method begins. In order to prevent the tempering air stream from being deprived of its coldness when it flows through the cold accumulator, it is ensured according to the invention that loading of the cold accumulator does not occur. This is achieved in that the temperature of the Temperierluftstroms is maintained above the phase transition temperature of the PCM material of the cold accumulator. This therefore does not undergo a phase transition, which would be a prerequisite for an effective memory load. However, this upholding of the Temperierlufttemperatur is not achieved by a reduced heat extraction in the evaporator. Rather, the invention provides, by means of the controllable fan to increase the strength of Temperierluftstroms so far that the registered in the Temperierluftstrom cold is not sufficient to achieve the phase transition temperature. However, nothing changes at the total amount of refrigerant introduced into the tempering air flow, so that the cooling of the vehicle interior loses nothing of its efficiency. Only the volume and speed of the tempering air blown into the vehicle interior is increased.

A subordinate advantage of this method is also that a possibly provided in the counter heat exchanger heat exchanger, which should prevent - even in the cool-down case - too cold, perceived as uncomfortable air is blown into the vehicle interior, turn out lower so that the cool-down process becomes more efficient and resource-efficient overall.

After the cool-down process, ie after reaching the target temperature of the vehicle interior, as provided in a preferred embodiment of the invention, the tempering air flow passing through the evaporator can be reduced to such an extent that the temperature of the temperature control air in the region of the cold accumulator falls below the phase transition temperature of the cold storage medium so that the cold storage medium is cooled below its phase transition temperature and undergoes a phase transition. After the rapid cooling of the vehicle interior, the air conditioning has namely only small temperature differences to overcome or counteract a continuous loss of cold. This requires only a small proportion of the total available cooling capacity. As a result, the air conditioning compressor can deliver more refrigeration than required to cool the vehicle interior. This excess cold can be used to load the cold storage. This requires no changes to the actual refrigerant circuit. Rather, it is sufficient to reduce the tempering air flow by means of the controllable fan. The unchanged available total cooling quantity then suffices to cool the reduced tempering air flow to a temperature below the phase transition temperature of the cold storage medium. If this cooled tempering air flows through the cold storage, it is charged in a known manner by phase transition. The heat released during this process is blown out into the vehicle interior with the tempering air flow. In the control of the blower is thus preferably to ensure that not only the phase transition temperature of the cold storage medium falls below, but the registered in the vehicle interior cold altogether sufficient to meet the current cooling requirements there. However, this should be included reasonable design of the air compressor on the one hand and the cold storage on the other hand always be easily possible.

After cool-down according to the invention and subsequent charging of the cold accumulator, the air conditioner is in a state that allows the bridging of short-term air compressor compressor downtime. Thus, in a further development of the invention, it is provided that in the case of disturbed provision of cold refrigerant for the flow through the evaporator, d. H. For example, during the stop phases of an automatic start / stop, the tempering air flow is maintained until the temperature of the cold storage medium exceeds its phase transition temperature again, d. H. until the cold storage is discharged. Whether the Temperierluftstrom whose temperature and humidity in the sequence will rise rapidly after the memory discharge further maintained, is switched off or reduced, can be determined by the expert in the light of the individual case in the context of the specific interpretation and is not relevant to the invention here.

In order to bridge compressor stop times as long as possible, it is provided in an advantageous embodiment that in the case of disturbed provision of cold refrigerant for the flow through the evaporator, the Temperierluftstrom is reduced. This is based on the consideration that it is cheaper in terms of comfort, due to a reduced tempering air flow to take a slight warming of the vehicle interior during a longer bridging time in purchase, as an exact constant maintenance of the interior temperature during a thus shortened bridging time.

The specific embodiment of the cold accumulator plays no role for the basic applicability of the control method according to the invention. For example, the cold storage could be configured as a tube structure filled with liquid PCM material. Examples of such liquid PCM materials are decanol, tetra-, penta- or hexadecane, Li-ClO ₃ 3H ₂ O, aqueous salt solutions or organic hydrates whose phase transition temperature is in the range from 0 ° C to 30 ° C, preferably between 1 ° C and 20 ° C, in particular between 2 ° C and 15 ° C and more preferably between 4 ° C and 12 ° C. In practice, however, the use of modern PCM composites is more favorable, so that in a preferred embodiment of the air conditioner according to the invention the cold storage has a plurality of parallel lamellae, between which flow air passages through which temperature air is formed, wherein the lamellae each comprise at least one plate of plastic-supported waxy PCM -Material exhibit. Such paraffin-based PCM composites are known to the person skilled in the art and are available, for example, from Rubitherm Technologies GmbH, Berlin, Germany, inter alia under the name Rubitherm PK. The advantage of such PCM composites lies in their "dry" state of aggregation on both sides of the phase transition.

However, freely questioning memory structures made of such material will not always have sufficient dimensional stability for use in motor vehicles. Even outgassing of the PCM material and thus a disadvantageous aging effect can be problematic. In a further development of the invention, it is therefore provided that the lamellae further each have two light metal plates, for example made of aluminum, between which the at least one plate of PCM material sandwiched and contacting both light metal plates is embedded. Such a structure obtains its stability substantially from the metal plates; their thermal properties, on the other hand, are determined by the PCM material which, due to the contact with the metal plates, is in thermal contact with the tempering air flow flowing around the lamellae. In view of a good heat exchange and a low weight of the cold accumulator, the light metal plates are preferably formed as thin sheets. However, this makes it difficult for large-area slats contact with the PCM material over the entire surface. In a preferred development it is therefore provided that at least one of the light metal plates of each slat has outwardly directed spacer elements, with which the slat is supported on an adjacent slat or wall. The spacer elements are preferably designed as nubs, pins or ribs distributed over the plate surface. In this way, a fin stack, which is clamped under pressure between two outer walls, firstly fulfill the support function for the PCM material, secondly provide flow channels for the Temperierluftstrom and thirdly, a good, heat-transferring contact between PCM material and metal plates over the entire fin surface to ensure.

In order to allow as unobstructed flow as possible, the fins are preferably oriented perpendicular to the Temperierluftstrom. In this case, they are preferably subdivided into a plurality of plate packs spaced apart from one another in the flow direction and staggered one behind the other. This results in slots between the disk packs, which are aligned perpendicular to the Temperierluftstrom and perpendicular to the slats. These shafts, which are preferably connected to drain lines or reservoir, serve the removal of condensation, so this is not the Narrowed flow cross sections for the tempering air flow.

Further features and advantages of the invention will become apparent from the following description and the drawings.

Show it:

1 a schematic representation of four stages of a preferred embodiment of the control method according to the invention,

2 a schematic representation of a preferred embodiment of the cold storage of the air conditioner according to the invention,

3 a schematic detail of the cold storage of 2 ,

Like reference numerals in the figures indicate like or analogous elements.

1 shows a highly schematic representation of four stages of a particularly preferred embodiment of the control method according to the invention of an automotive air conditioning system 10 , The refrigerant circuit 20 is constructed in a conventional manner, ie, a refrigerant is in an air conditioning compressor 22 , which is mechanically connected to the drive unit of the motor vehicle, compressed. The compressed and thus heated refrigerant is cooled in an unillustrated, compressor-side heat exchanger back to ambient temperature T0. The cooled and compressed refrigerant is cooled further with an expansion device 24 relaxed and an evaporator 30 supplied, where it evaporates at a minimum temperature Tmin and the energy required for evaporation a Temperierluftstrom 40 from which the evaporator 30 flows through simultaneously, withdraws. The tempering air flow is driven by a controllable fan. By heat exchange in the evaporator 30 becomes the tempering air flow 40 to a temperature T which should be less than the ambient temperature T0 cooled. The thus cooled tempering air flow 40 then passes through a downstream of the evaporator 30 arranged cold storage 60 and leaves it at a temperature T that depends on the current state of the air conditioning. With this temperature T, the Temperierluftstrom 40 in a manner not shown either directly or - usually - blown after passing through a counterheating heat exchanger in the interior of the vehicle.

1a shows the process step of the so-called cool-down, ie the rapid cooling of the vehicle interior. This is necessary, for example, if the vehicle has been parked for a long time in the sun and has heated up considerably. Here, the primary goal is to get to a comfortable interior temperature as quickly as possible. This is the blower 50 controlled so that a strong Temperierluftstrom 40 results, as shown by the thick flow arrow. From the large flow volume follows a large total heat capacity of Temperierluftstroms 40 that is so great that the heat extraction in the evaporator 30 insufficient, the temperature of the Temperierluftstroms 40 to a temperature below the phase transition temperature Tpc of the PCM material in the cold storage 60 cool. For example, the phase transition temperature Tpc could be about 6 ° C; the outlet temperature of the Temperierluftstroms 40 from the evaporator 30 could then for example be between 6 ° C and 10 ° C. This flows through the Temperierluftstrom 40 the cold storage 60 without significant temperature change. The whole in the evaporator 30 absorbed amount of refrigerant is available without delay to cool the vehicle interior.

1b shows a process step after reaching the target temperature of the vehicle interior. In this phase, only small cooling losses are to be compensated or to realize low, desired by the driver temperature changes. The amount of cold required for this is well below the maximum amount of refrigerant that can provide the air conditioning. As indicated by the thin flow arrow, in this stage, the blower 50 controlled so that only a small Temperierluftstrom the evaporator 30 flows through. Correspondingly smaller is the total heat capacity of the Temperierluftstroms. With the same performance of the refrigerant circuit 20 thus follows a stronger cooling of Temperierluftstroms 40 , in particular to a temperature T, which is below the phase transition temperature Tpc of the cold accumulator 60 lies. Consequently, the cold storage 60 cooled as it flows through with cold tempering air so far that its PCM material undergoes a phase transition. The released heat is released to the Temperierluftstrom, depending on the design of the system, the cold storage 60 leaves at a temperature which corresponds approximately to the phase transition temperature Tpc. In this process step, the cold storage 60 loaded.

1c illustrates the process step of normal operation at gem. 1b charged cold storage 60 , The refrigerant circuit runs in a conventional manner. The fan 50 generates a tempering air flow according to the requirements 40 as indicated by the middle-thick arrow. This is in the heat exchanger 30 cooled down so far that its temperature is at least not significantly above the phase transition temperature Tpc. The so tempered tempering air flow 40 goes through the cold storage 60 practically without temperature change. In particular, the state of charge of the cold accumulator changes 60 Nothing.

1d Finally, the process stage shows the failure of the refrigerant circuit, such as occurs in stop phases of an automatic start / stop system. In this phase, no refrigerated refrigerant passes through the evaporator 30 so that its temperature rises rapidly, but will remain below ambient temperature T0 for not too long stop phases. In this stage of the process, the blower 50 driven to a reduced operation, as indicated by the thin flow arrow. The cooling, the tempering air flow when flowing through the evaporator 30 experiences, is only small. In particular, the downstream cold storage 60 flows through at a temperature which is well above the phase transition temperature. As a result, the PCM material of the cold accumulator 60 excited to a new phase transition, the heat required for this purpose removed from the Temperierluftstrom and this is thus cooled. The resulting airflow temperature depends on the ambient temperature T0 and the capacity of the cold storage 60 from. In any case, this can be done even when the refrigerant circuit is stopped 20 a further cooling of the vehicle interior done, but decreases with time.

When re-starting the refrigerant circuit 20 Depending on the duration of the standstill, the control method can be based on the current tempering state with each of the subfigures 1a . 1b or 1c will be continued.

2 shows a possible embodiment of the arrangement of the cold accumulator 60 , Shown is a pipe transition piece between the unillustrated evaporator on the left side of 2 and the vehicle interior, also not shown. The cold storage 60 is in several, in the exemplary embodiment, three packages within a serving as a housing plastic channel 70 arranged with rectangular cross-section. The individual cold storage packages are through downshafts 72 separated from each other, which are connected in a manner not shown with drain pipes and / or reservoir for draining or collecting condensation. The outlet side is the cold storage 60 a counterheating heat exchanger 80 downstream, which is connected in a manner not shown with the drive unit of the motor vehicle, so that its exhaust air the counterheating heat exchanger 80 can flow through.

3 shows a highly schematic representation of a section of one of the memory packs of the cold storage 60 from 3 , The cold storage 60 is as a set of slats arranged in parallel 62 built up. Each lamella comprises a thin, for example 2 mm thick plate of a waxy, plastic-based PCM composite 64 , This is sandwiched between two thin, for example, 0.5 mm thick aluminum plates 66 arranged. The PCM composite board 64 and the aluminum sheets 66 contact each other over the entire surface. At their front sides are the lamellae 62 in slit-like guides 74 of the plastic housing 70 guided. The lamellae are preferred 62 with a clear game in the guides 74 guided. This allows a lateral tolerance compensation. The aluminum sheets 66 are with pimples 68 provided as spacer elements between the slats 62 as well as between the slats 62 and the housing wall 70 serve. With suitable dimensioning, the slats are supported by the knobs 68 against each other and against the housing wall 70 so that the lamellae are under lateral pressure. This pressure improves the contact between the aluminum sheets 66 and the PCM composite panels sandwiched between them 64 , The flow direction of the Temperierluftstroms is perpendicular to the slats, ie in 3 perpendicular to the drawing plane.

Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. In the light of the disclosure herein, those skilled in the art will be offered a wide range of possible variations. In particular, the special dimensioning and design, in particular capacity design of the individual elements can be adapted by the person skilled in the art to the requirements of the individual case.

LIST OF REFERENCE NUMBERS

10

air conditioning

20

Refrigerant circuit

22

air compressor

24

Exansionsorgan

30

Evaporator

40

Temperierluftstrom

50

fan

60

cold storage

62

lamella

64

PCM composite plate

66

Light sheet metal

68

Shag / spacer element

70

channel housing

72

downcomer

74

guide slot

80

Gegenheiz heat exchanger

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006028017 A1 [0003, 0005]

Claims (10)

Air conditioning system for a motor vehicle, comprising - one of refrigerant and of tempering air ( 40 ) permeable evaporator ( 30 ) and - at least one of the tempering air ( 40 ) throughflowable cold storage ( 60 ), whose cold storage medium is a PCM material ( 64 ), and - a controllable fan ( 50 ), by means of which the tempering air flow ( 40 ) through the evaporator ( 30 ) and the cold storage ( 60 ) is controllable, characterized in that the non-flowed through by the refrigerant cold storage ( 60 ) downstream of the evaporator ( 30 ) is arranged. Air conditioning system according to claim 1, characterized in that the cold storage ( 60 ) a plurality of parallel slats ( 62 ), between which of tempering air ( 40 ) flow-through flow channels are formed, wherein the slats ( 62 ) at least one plate ( 64 ) made of plastic-supported, waxy PCM material. Air conditioning system according to one of the preceding claims, characterized in that the lamellae ( 62 ) each two light metal plates ( 66 ) between which the at least one plate ( 64 ) of PCM material sandwiched and both light metal plates ( 66 ) is embedded in contact. Air conditioning system according to claim 3, characterized in that at least one of the light metal plates ( 66 ) each lamella ( 62 ) outwardly directed spacer elements ( 68 ), with which the lamella ( 62 ) on an adjacent lamella ( 62 ) or wall ( 70 ) is supported. Air conditioning system according to one of the preceding claims, characterized in that the lamellae ( 62 ) perpendicular to the tempering air flow ( 40 ) and are subdivided into a plurality of lamination packets staggered one behind the other in the flow direction. Method for controlling a motor vehicle air conditioning system ( 10 ), comprising - one of refrigerant and tempering air ( 40 ) permeable evaporator ( 30 ) and - at least one of the tempering air ( 40 ) throughflowable cold storage ( 60 ), whose cold storage medium is a PCM material ( 64 ), wherein for rapid cooling of a vehicle interior from a higher starting temperature to a lower target temperature of the evaporator ( 30 ) simultaneously from cold refrigerant and the tempering air ( 40 ) and the cold storage ( 60 ) at least from the tempering air ( 40 ) flows through and the tempering air ( 40 ) is blown into the vehicle interior, characterized in that the the evaporator ( 30 ) passing tempering air flow ( 40 ) is set so high until the first time the target temperature of the vehicle interior is reached, that the temperature of the tempering air ( 40 ) in the region of the downstream of the evaporator ( 30 ) cold storage ( 60 ) the phase transition temperature (Tpc) of the cold storage medium ( 69 ) does not fall below. A method according to claim 6, characterized in that after reaching the target temperature of the vehicle interior of the evaporator ( 30 ) passing tempering air flow ( 40 ) is reduced so far that the temperature of the tempering air ( 40 ) in the region of the cold storage ( 60 ) the phase transition temperature (Tpc) of the cold storage medium ( 64 ), so that the cold storage medium ( 64 ) is cooled below its phase transition temperature (Tpc) and undergoes a phase transition. A method according to claim 7, characterized in that in the case of disturbed provision of cold refrigerant to flow through the evaporator ( 30 ) the tempering air flow ( 40 ) is maintained until the temperature of the cold storage medium ( 64 ) whose phase transition temperature (Tpc) again exceeds. A method according to claim 8, characterized in that in the case of disturbed provision of cold refrigerant for flow through the evaporator ( 30 ) the tempering air flow ( 40 ) is reduced. Method according to one of claims 5 to 9, characterized in that the tempering air flow ( 40 ) by means of a controllable blower ( 50 ) is set.

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