DE102023126888A1 - Method for emptying a refrigeration system of a motor vehicle and refrigeration system for carrying out the method - Google Patents

Abstract

A method (500) is described for substantially completely emptying, in particular extracting, a quantity of refrigerant from a refrigeration system (10) of a motor vehicle (100), comprising the steps of: providing (S501) at least one extraction device (50) separate from the refrigeration system (10); connecting (S502) the extraction device (50) to at least one service connection (26-1, 26-2) arranged on the refrigeration system (10), which service connection is in particular designed for emptying and filling the refrigerant of the refrigeration system (10); starting (S503) the extraction of refrigerant at a first extraction rate (vA1); adjusting (S505) the first extraction rate (vA1) after a predetermined period of time (Tv1) has elapsed since starting and/or after a predetermined refrigerant pressure (pKM) has been reached in the refrigeration system (10); wherein, during the adjustment (S505) of the first extraction speed (vA1), the setting to a lower, second extraction speed (vA2) takes place, and wherein the second extraction speed (vA2) is subsequently repeatedly reduced further using a gradient (S507). Furthermore, a refrigeration system (10) for carrying out the method (500) is described.

Description

The invention relates to a method for substantially completely emptying, in particular extracting, a quantity of refrigerant from a refrigeration system of a motor vehicle and to a refrigeration system for a motor vehicle which is or can be connected to a suction device for carrying out the method.

It is well known that the refrigerant contained in refrigeration systems must be extracted for maintenance purposes. For this purpose, the refrigeration system has at least one service connection, which can also be referred to as a filling valve. A suction device, which can also be referred to as a service unit, is connected to the service connection to extract the refrigerant from the refrigeration system. The extraction usually takes place with the refrigerant valves in the refrigeration system open, if present and externally controllable, such as shut-off valves, expansion valves or the like, so that the amount of refrigerant required for normal operation of the refrigeration system can be extracted as completely as possible from the refrigeration system or the refrigeration system can be emptied. The service unit works in such a way that the extraction process is terminated when a predetermined system pressure is reached or detected. This can lead to partial icing due to an excessively rapid pressure drop in the refrigeration system and/or a residual charge of refrigerant remaining in the refrigeration system. This is undesirable for reasons of occupational health and environmental protection.

The state of the art is exemplified by the CN 217058052 U , EP 2 562 492 A1 , EP 2 944 486 A1 , DE 10 2018 205 432 A1 and DE 10 2017 208 227 A1 pointed out.

The object underlying the invention is to provide a method for emptying, in particular evacuating, a quantity of refrigerant from a refrigeration system that avoids the above-mentioned disadvantages. Furthermore, a refrigeration system is to be provided whose structure enables the implementation of the method.

This problem is solved by a method and a refrigeration system having the features of the respective independent patent claim. Advantageous embodiments with useful further developments are specified in the dependent patent claims.

• Bereitstellen von wenigstens einer von der Kälteanlage gesonderten Absaugvorrichtung; Anschließen der Absaugvorrichtung an wenigstens einem an der Kälteanlage angeordneten Serviceanschluss, der insbesondere zum Entleeren und Befüllen des Kältemittels der Kälteanlage eingerichtet ist;
• Starten des Absaugens von Kältemittel mit einer ersten Absauggeschwindigkeit; Anpassen der ersten Absauggeschwindigkeit nach Ablauf einer vorbestimmten Zeitdauer seit dem Starten oder/und nach Erreichen eines vorbestimmten Kältemitteldrucks in der Kälteanlage; wobei beim Anpassen der ersten Absauggeschwindigkeit das Einstellen auf eine tiefere, zweite Absauggeschwindigkeit erfolgt und wobei die zweite Absauggeschwindigkeit anschließend unter Verwendung von einem Gradienten wiederholt weiter abgesenkt wird.

A method is therefore proposed for the essentially complete emptying, in particular suction, of a quantity of refrigerant from a refrigeration system of a motor vehicle, comprising the steps:

• Providing at least one extraction device separate from the refrigeration system; connecting the extraction device to at least one service connection arranged on the refrigeration system, which is particularly designed for emptying and filling the refrigerant of the refrigeration system;
• Starting the recovery of refrigerant at a first recovery rate; adjusting the first recovery rate after a predetermined period of time has elapsed since starting and/or after reaching a predetermined refrigerant pressure in the refrigeration system; wherein, when adjusting the first recovery rate, the setting to a lower, second recovery rate takes place and wherein the second recovery rate is subsequently repeatedly reduced further using a gradient.

This ensures that, when the (residual) refrigerant quantity in the refrigeration system decreases, this (residual) refrigerant quantity is not evaporated and extracted so quickly that undesirable icing occurs.

Furthermore, it has been shown that such a method with an adaptive extraction rate enables better evacuation. Although the proposed method somewhat extends the entire extraction process due to the adaptive or reduced extraction rate, it leads to better results in terms of the (residual) refrigerant quantity remaining in the refrigeration system after extraction.

For example, it is conceivable to initially extract refrigerant from the refrigeration system at a maximum (first) extraction rate until a system pressure of approximately 3 bar is reached. The (first) maximum extraction rate is then reduced using a gradient of, for example, 0.5 bar/min. Alternatively, it is also possible to start with an initial extraction rate that is reduced using a gradient of, for example, 1 bar/min, independent of the system pressure. After a certain period of time or when a certain system pressure is reached, the gradient can be adjusted to, for example, 0.2 bar/min.

With regard to the procedure, it should be noted that in the case of a gradual reduction, each suction speed reduced again according to the gradient is to be understood as a “second suction speed”, which, compared to the immediately previously used or set extraction speed is reduced.

In the method, at least one component of the refrigeration system, in particular a low-pressure side refrigerant reservoir, can be heated during extraction at the first extraction speed and/or at the second extraction speed. This can assist the evaporation of the refrigerant, allowing it to be extracted more effectively and completely.

In the method, the extraction device can be connected to two service connections, with a first service connection being provided on the low-pressure side of the refrigeration system and a second service connection being provided on the high-pressure side of the refrigeration system. In this context, it is also conceivable for a respective extraction device to be connected to each service connection.

Also proposed is a refrigeration system for a motor vehicle, wherein the refrigeration system is connectable or connected to an extraction device for carrying out the method described above, comprising a refrigerant compressor; a first heat exchanger, in particular a condenser or gas cooler; a second heat exchanger, in particular an evaporator; a low-pressure refrigerant accumulator arranged downstream of the evaporator; a first service connection arranged on the low-pressure side downstream of the second heat exchanger; and a second service connection arranged on the high-pressure side downstream of the first heat exchanger.

In the refrigeration system, the refrigerant storage tank can be connected to a heating device that is designed to heat the refrigerant storage tank and the refrigerant contained therein as required.

The heating device can be designed to heat the refrigerant storage tank on its outside and/or in its interior.

In the refrigeration system, the first service connection can be located on a housing of the refrigerant storage unit or on a service line connected to the housing of the refrigerant storage unit. The service line is separate from the refrigerant lines through which the refrigerant circulates during refrigeration system operation. This can provide a flow path with as little resistance as possible when extracting refrigerant.

Alternatively, the first service connection of the refrigeration system can be located downstream of the refrigerant storage tank.

The refrigeration system may further comprise a third heat exchanger, in particular a chiller, which is arranged parallel to the second heat exchanger with respect to the refrigerant flow direction and which is connected to a coolant circuit in such a way that heat transfer is possible between the coolant and the refrigerant.

At least one coolant line section of the coolant circuit can be designed as a heating device for the refrigerant storage tank. This makes it possible to utilize waste heat from the coolant circuit to assist in draining the refrigeration system.

• 1 ein schematisches und vereinfachtes Ablaufdiagramm eines Verfahrens zum Entleeren einer Kälteanlage;
• 2 eine vereinfachte und schematisches Darstellung einer Kälteanlage eines Kraftfahrzeugs mit Absaugvorrichtung zur Durchführung des Verfahrens;
• 3 eine vereinfachte und schematische Schnittansicht eines Kältemittelspeichers mit einem Serviceanschluss.

Further advantages and details of the invention will become apparent from the following description of embodiments with reference to the figures.

• 1 a schematic and simplified flow diagram of a method for emptying a refrigeration system;
• 2 a simplified and schematic representation of a refrigeration system of a motor vehicle with an extraction device for carrying out the method;
• 3 a simplified and schematic sectional view of a refrigerant storage tank with a service connection.

In 1 is a simplified and schematic diagram of a method 500 for substantially completely emptying, in particular extracting, a quantity of refrigerant from a refrigeration system of a motor vehicle.

In step S501, at least one extraction device separate from the refrigeration system is provided. According to step S502, the extraction device is connected to at least one service connection arranged on the refrigeration system, which is configured, in particular, for emptying and filling the refrigeration system's refrigerant.

According to a step S503, the refrigerant recovery is started at a first recovery speed vA1.

In step S504, it is checked whether a predetermined time period Tv1, during which the first suction speed is active, has elapsed. The predetermined time period can, for example, be from 0 to 120 seconds. If the predetermined time period Tv1 is reached, the first suction speed vA1 is adjusted in a step S505.

Alternatively or additionally, in step S506, it can be checked whether a predetermined refrigerant pressure pKM has been reached in the refrigeration system. If the predetermined refrigerant pressure pKM is reached, the first extraction rate vA1 can be adjusted in step S505.

When adjusting the first suction speed vA1 in step S505, the setting to a lower, second suction speed vA2 takes place, wherein the second suction speed vA2 is subsequently repeatedly reduced further according to a step S507 using a gradient.

In method 500, according to a step S508, at least one component, in particular a low-pressure side refrigerant reservoir, of the refrigeration system is heated during the extraction at the first extraction speed vA1 and/or at the second extraction speed vA2. Step S508 can be performed depending on detected parameters of the refrigeration system.

In method 500, the suction device can be connected to two service connections in step S502, wherein a first service connection is provided on the low-pressure side of the refrigeration system and wherein a second service connection is provided on the high-pressure side of the refrigeration system.

With the method 500, it can be ensured that, as the (residual) refrigerant quantity in the refrigeration system decreases, this (residual) refrigerant quantity is not evaporated and extracted so quickly that undesirable icing occurs, particularly due to cooling component surfaces and thus residual quantities of refrigerant in the system. Furthermore, it has been shown that such a method 500 with an adapting extraction speed enables better emptying. Although the proposed method somewhat extends the entire (individual) extraction process due to the adapting or reducing extraction speed, it leads to better results with regard to the (residual) refrigerant quantity remaining in the refrigeration system after extraction.

However, this approach eliminates the need for a second or even third recovery routine, depending on the complexity of the system being processed, which can range from a simple refrigeration system to a complex heat pump system. This also results in significant differences in the required initial refrigerant charge and, consequently, the amount of refrigerant to be recovered.

For example, it is conceivable to first extract refrigerant from the refrigeration system in step S503 at a maximum (first) extraction rate vA1 until a system pressure pKM of approximately 3 bar is reached. The (first) maximum extraction rate vA1 is then reduced using a gradient of, for example, 0.5 bar/min. Alternatively, step S503 can also begin with a certain predetermined first extraction rate vA1, which is reduced with a gradient of, for example, 1 bar/min regardless of the system pressure. After a certain period of time Tv1 or when a certain system pressure pKM is reached, the gradient can be adjusted to, for example, 0.2 bar/min.

The method 500 described above can be used, for example, in 2 refrigeration system 10 shown as an example of a motor vehicle 100 shown here only in a simplified manner.

The refrigeration system 10 is shown here purely as an example as a type of basic system, which, however, can also have further components not shown here, such as further heat exchangers, for example a heating register for a heat pump application, and the like.

The refrigeration system 10 has a refrigerant compressor 12, a first heat exchanger 14, in particular a gas cooler or condenser, a second heat exchanger 16, in particular an evaporator, and a low-pressure side refrigerant storage tank 18.

Optionally, the refrigeration system may include an internal heat exchanger 20. Furthermore, the refrigeration system may optionally include a third heat exchanger 22, in particular a chiller, connected to a coolant circuit 24, wherein the coolant circuit 24 is configured to cool at least one electrical component of the motor vehicle, such as an electric drive device, high-voltage battery, or the like.

The refrigeration system 10 comprises at least one service connection 26.

In the example shown, the refrigeration system 10 has a low-pressure side first service connection 26-1 and a high-pressure side service connection 26-2.

The low-pressure side service connection 26-1 is arranged downstream of the second heat exchanger 16 or the optional third heat exchanger 22.

The low-pressure side service connection 26-1 can be arranged upstream or downstream of the refrigerant storage 18, which is illustrated by the dashed representation of the first service connection 26-1.

Alternatively, it is also possible for the service connection 26-1 not to be provided on a line section of the refrigerant circuit, but rather to be arranged on a housing of the refrigerant storage unit 18 or on a service line 28 connected to the housing of the refrigerant storage unit 18. The service line 28 is separate from the refrigerant lines through which the refrigerant circulates during refrigeration system operation.

It should be noted that a first service connection 26-1 is usually provided only at one of the positions described above, i.e. upstream or downstream of the refrigerant reservoir 18 on a line section of the refrigerant circuit or on the refrigerant reservoir 18 itself, if necessary by means of a service line 28.

The high-pressure-side second service port 26-2 is arranged downstream of the first heat exchanger 14. In particular, it can be arranged between the first heat exchanger 14 and the second heat exchanger 16 or the optional third heat exchanger 22.

In addition, 1 an extraction device 50 separate from the refrigeration system 10 is illustrated, which is coupled to at least one service connection 26-1, 26-2 for carrying out the method 500 described above, which is illustrated by the dashed connecting lines.

The suction device 50 can in particular be coupled to the first, low-pressure side service connection 26-1 and the second, high-pressure side service connection 26-2.

As already mentioned above with respect to method 500, in the method at least one component of the refrigeration system can be heated during or during the recovery of refrigerant.

For example, the low-pressure side refrigerant storage 18 can be heated in order to make the refrigerant volume contained or stored therein more readily available for extraction, in particular in such a way that icing or excessive cooling of the component surfaces can be prevented.

The heating of the refrigerant storage 18 can be carried out by means of a temporarily or permanently installed heating device 30, which is 2 simplified as a schematic rectangle on the refrigerant storage tank.

The heating device 30 can, for example, be electrically operated, for example in the manner of a heating band or heating sleeve attached to the refrigerant storage 30.

Such a heating band or heating sleeve can, for example, be arranged flatly at least partially along the circumference of the refrigerant reservoir 18. The extension of the heating band or heating sleeve in the vertical direction of the refrigerant reservoir can be determined depending on whether the heating band or heating sleeve is arranged or provided over the entire circumference or only part of the circumference of the refrigerant reservoir. Furthermore, when attaching the heating band or heating sleeve, it is necessary to consider the installation space actually available in the area of the refrigerant reservoir 18 or the space that is advantageously accessible for temporary installation.

In the case of a circumferential heating sleeve, it is conceivable that it can be or is temporarily attached to the refrigerant storage unit 18, in particular for the purpose of carrying out the method 500 described above. The heating sleeve can be arranged and closed circumferentially on the refrigerant storage unit, for example, using a hook-and-loop fastener. Of course, other fastening methods are also conceivable, such as temporary adhesive/bonding connections and the like.

The heating device 30 can alternatively be formed by at least one coolant line section 24h of the coolant circuit 24.

The heating device 30 can also be formed by a (heating/warm air) fan or the like, which is designed to allow heated ambient air to flow, as required, in an undirected or directed manner to the refrigerant storage device 18.

With regard to possible embodiments of a refrigerant accumulator 18 with a heating device, reference is also made to the German patent applications filed simultaneously by the applicant with the titles “Refrigerant accumulator with heating line section through which heating fluid flows, thermal management system with such a refrigerant accumulator and motor vehicle with such a thermal management system” and “Air conditioning system for a motor vehicle with heating air duct section to a refrigerant accumulator and motor vehicle with such an air conditioning system”.

Alternatively or in addition to heating the refrigerant storage 18, it is also conceivable bar that the second heat exchanger 16 is supplied with ambient air heated as needed, so that the second heat exchanger 16 can be heated instead of or in addition to the refrigerant storage 18.

It is conceivable that a common air flow direction, as shown in the 2 is shown by arrows above and below the second heat exchanger 16, is reversed, so that, for example, air can be sucked in from an interior of the motor vehicle, which is then heated by optional electrical air heating elements and conveyed in the direction of the second heat exchanger 16.

Alternatively or in addition to heating the refrigerant storage 18, it is also conceivable that the optional third heat exchanger 22 is heated, wherein for this purpose the coolant continues to circulate in the coolant circuit 24 during the extraction of refrigerant, so that, for example, waste heat from a previously used electrical component can be used.

It is also conceivable that any electrical coolant heaters present in the coolant circuit 24 are used to heat the coolant to a desired temperature so that appropriate heating of the refrigerant can be achieved in the third heat exchanger 22.

Regarding the 2 It should also be noted that known elements of a refrigeration system 10 are also illustrated therein, such as a plurality of sensors pT1, pT2, pT3 for detecting the pressure and/or temperature of the refrigerant and expansion valves AE1, AE2. It should be noted that these components are purely exemplary in their number and arrangement. Other sensors and/or valves of the same or a different design can also be used. Furthermore, the refrigeration system 10 can also have additional heat exchangers or a modified topology, wherein the above statements regarding the emptying method 500 or the arrangement of service connections 26-1, 26-2 or the heatability of components of the refrigeration system 10 are also applicable to a different design of a refrigeration system 10.

In 3 A refrigerant accumulator 18 is shown in a simplified and schematic sectional view. First service connections 26-1 are shown by dashed lines at various possible positions on a housing 18g of the refrigerant accumulator. The first service connections 26-1 are shown on the right half of the refrigerant accumulator 18 with respect to the figure, but could also be arranged on the left side.

Furthermore, 3 On the left side of the refrigerant reservoir 18, several options for a service line 28 are illustrated, on which a first service connection 26-1 is provided. The service line 28 is a non-active part of the refrigerant circuit through which refrigerant flows during normal operation of the refrigeration system 10.

The 3 serves in particular to implement the above-mentioned provisions with reference to the 2 to illustrate the already described arrangement of a first service connection 26-1 on the refrigerant reservoir 18, in particular if the first service connection 26-1 is not intended to be or is not provided on a line section of the refrigerant circuit of the refrigeration system 10.

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

• CN 217058052 U [0003]
• EP 2 562 492 A1 [0003]
• EP 2 944 486 A1 [0003]
• DE 10 2018 205 432 A1 [0003]
• DE 10 2017 208 227 A1 [0003]

Claims (10)

A method (500) for substantially completely emptying, in particular extracting, a quantity of refrigerant from a refrigeration system (10) of a motor vehicle (100), comprising the steps of: Providing (S501) at least one extraction device (50) separate from the refrigeration system (10); Connecting (S502) the extraction device (50) to at least one service connection (26-1, 26-2) arranged on the refrigeration system (10), which is configured, in particular, for emptying and filling the refrigerant of the refrigeration system (10); Starting (S503) the extraction of refrigerant at a first extraction rate (vA1); Adjusting (S505) the first extraction rate (vA1) after a predetermined period of time (Tv1) has elapsed since starting and/or after reaching a predetermined refrigerant pressure (pKM) in the refrigeration system (10); wherein, when adjusting (S505) the first suction speed (vA1), the setting to a lower, second suction speed (vA2) takes place and wherein the second suction speed (vA2) is subsequently repeatedly reduced further using a gradient (S507). Procedure (500) according to Claim 1 , wherein during the suction (S503, S505, S507) at the first suction speed (vA1) and/or at the second suction speed (vA2) at least one component, in particular a low-pressure side refrigerant reservoir (18), of the refrigeration system (10) is heated (S508). Procedure (500) according to Claim 1 or 2 , wherein the suction device (50) is connected to two service connections (26-1, 26-2), wherein a first service connection (26-1) is provided on the low-pressure side of the refrigeration system (10) and wherein a second service connection (26-2) is provided on the high-pressure side of the refrigeration system (10). Refrigeration system (10) for a motor vehicle (100), wherein the refrigeration system (10) is provided with a suction device (50) for carrying out the method (500) according to one of the Claims 1 until 3 connectable or connected to a refrigerant compressor (12); a first heat exchanger (14), in particular a condenser or gas cooler; a second heat exchanger (16), in particular an evaporator; a low-pressure side refrigerant accumulator (18) arranged downstream of the evaporator (16); a first service connection (26-1) arranged on the low-pressure side downstream of the second heat exchanger (16); a second service connection (26-2) arranged on the high-pressure side downstream of the first heat exchanger (14). Refrigeration system (10) according to Claim 4 , wherein the refrigerant storage (18) is connected to a heating device (30) which is designed to heat the refrigerant storage (18) and the refrigerant contained therein as required. Refrigeration system (10) according to Claim 5 , wherein the heating device (30) is designed to heat the refrigerant storage (18) on its outside and/or in its interior. Refrigeration system (10) according to one of the Claims 4 until 6 , wherein the first service connection (26-1) is arranged on a housing (18g) of the refrigerant storage (18) or on a service line (28) connected to the housing (18g) of the refrigerant storage (18), wherein the service line (28) is separate from the refrigerant lines through which refrigerant circulates during refrigeration system operation. Refrigeration system (10) according to one of the Claims 4 until 6 , wherein the first service connection (26-1) is arranged downstream of the refrigerant storage (18). Refrigeration system (10) according to one of the Claims 4 until 8 , wherein it further comprises a third heat exchanger (22), in particular a chiller, which is arranged parallel to the second heat exchanger (16) with respect to the refrigerant flow direction and which is connected to a coolant circuit (24) such that heat transfer is possible between the coolant and the refrigerant. Refrigeration system (10) according to one of the Claims 5 until 8 and after Claim 9 , wherein at least one coolant line section (24h) of the coolant circuit (24) is designed as a heating device (30) for the refrigerant reservoir (18).

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