SERVICE UNIT FOR VEHICLE AIR-CONDITIONING SYSTEMS AND METHOD FOR REMOVING THE COOLANT OR A COOLANT/COMPRESSOR OIL MIXTURE FROM A VEHICLE AIR-CONDITIONING SYSTEM

Abstract

The invention relates to a service unit for vehicle air-conditioning systems, which is provided with an emptying and filling device for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system and replenishing the vehicle air-conditioning system with coolant and optionally with compressor oil. The device can include at least one tank for coolant and a vacuum pump for generating a negative pressure in the vehicle air-conditioning system emptied of coolant or coolant/compressor oil mixture for a subsequent intake of coolant and optionally compressor oil into the vehicle air-conditioning system to be replenished. A chimney-like gas-collecting chamber having upper and lower openings can be arranged inside the service unit and is otherwise sealed off from the surrounding atmosphere.

Description

FIELD OF THE INVENTION

The invention relates to a service unit for vehicle air-conditioning systems having the features of the preamble of claim 1 and a method for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system having the features of the preamble of claim 10.

TECHNOLOGICAL BACKGROUND

A vehicle air-conditioning system to be maintained consists substantially of a generally oil-lubricated compressor, a condenser, an evaporator, and pipelines which form a closed coolant system between these components. Furthermore, a dryer is generally provided, which can also act as a collector or reservoir for coolant. Finally, two service connections are incorporated in the coolant circuit for fluid exchange. The cold available at the evaporator in the vehicle is conducted away by a cold air blower and fed to the vehicle interior. The condensation heat of the condenser is conducted away by a warm air blower. Service connection connectors on the vehicle air-conditioning system allow coolant/compressor oil mixture to be drawn off or added at at least one, in particular the low-pressure (NP) service connection during maintenance. The vehicle air-conditioning systems differ from vehicle type to vehicle type and do not form the subject matter of the present invention.

Service units for vehicle air-conditioning systems serve among other things to drain the coolant circuit of a wide variety of vehicle air-conditioning systems from time to time and introduce a new coolant filling during maintenance. In this case it is necessary to observe precise quantities and coolant specifications. Moreover, in many cases lubricating oil for the compressor of the coolant circuit of the vehicle air-conditioning system must be removed and replenished. This also takes place in quantities and specifications depending on the vehicle type and air-conditioning unit type. Some vehicle air-conditioning systems also require an additive for the coolant circuit, which is likewise partially replaced during maintenance. Usually, the compressor oil passes into the coolant circuit and is circulated as well during operation of the vehicle air-conditioning system. Only very specific pairings of coolant and compressor oil are compatible with each other for this purpose. In order to be able to recover at least some of the coolant for reuse after extraction of the coolant/compressor oil mixture, service units for vehicle air-conditioning systems usually also have a separator, with which coolant can be separated from the coolant/compressor oil mixture for reuse. Used compressor oil and where necessary used additive is generally collected by the service unit in order to be discarded later.

WO 2007/085480 of the applicant discloses a service unit for vehicle air-conditioning systems according to the block diagram and FIG. 1. This shows the essential constituents of the generic service unit for a vehicle air-conditioning system in solid lines and a vehicle air-conditioning system to be maintained in dashed lines. The latter consists of an oil-lubricated compressor 1, a condenser 2, an evaporator 3, and pipelines 4A-4C forming a closed coolant system between these components. Furthermore, a dryer 5 is provided, which can also act as a collector or reservoir for coolant. Finally, two service connections 6a/6b are incorporated in the coolant circuit for fluid exchange. The cold available at the evaporator 3 in the vehicle is conducted away by a cold air blower 7 and fed to the vehicle interior. The condensation heat of the condenser 2 is conducted away by a warm air fan 8. Service connection connectors 9A and 9B allow coolant/compressor oil mixture to be drawn off and added at the service connections 6A, 6B during maintenance. The vehicle air-conditioning system labelled 10 overall differs from vehicle type to vehicle type and does not form the subject matter of the present invention.

A service unit, labelled 20 overall, for a vehicle air-conditioning system has flexible pressure hoses 11A, 11B for connecting the service unit 20 to the vehicle air-conditioning system 10 by means of the service connection connectors 9A, 9B at the service connections 6A, 6B. An extraction pump 12 configured as a coolant compressor delivers used coolant/compressor oil mixture via the pressure hoses 11A and 11B and the separator 14. The latter separates coolant from the extracted mixture by evaporation and feeds it to a coolant store 15 configured as a pressurised tank. Compressor oil/additive mixture separated off in the separator 14 is collected in a replaceable used oil tank 15 and its weight is detected by means of a weighing device 17A. An air-cooled coolant condenser 15A is connected fixedly to the coolant store 15. Recycled coolant is thereby fed predominantly in liquid form to the coolant store 15. The whole coolant store including the condenser rests on a further weighing device 17B for detecting the coolant fed and discharged and in store. After the extraction of the used mixture, a vacuum pump 13 provides the underpressure, which is necessary for refilling, in the circuit of the vehicle air-conditioning system and emits the extracted gas volume to the atmosphere.

A refilling system labelled 19 overall consists substantially of replaceable storage tanks 19D for compressor oil and 19C for additives, a control unit 19A with a valve block and control lines 19B, a remote display 19E and metering and valve units 19F′ to 19F′″. The storage tanks 19C and 19D can preferably be weighed. Further weighing devices 17C, 17D are used for this purpose.

DE 20 2008 003 123 U1 discloses a further service unit for vehicle air-conditioning systems of the applicant, in which the ability of the previously evacuated vehicle air-conditioning system to be refilled is improved by a heat source, which is provided in the coolant storage tank and serves to increase the pressure of the coolant.

The still unpublished German Patent Application No. 10 2009 054 436.4 of the applicant, filed on 25 Nov. 2009, the disclosure content of which is included in the present patent application, discloses detecting the quantities of coolant initially present in the coolant circuit system of the vehicle air-conditioning system as precisely as possible during maintenance of vehicle air-conditioning systems, in order to improve diagnosis of the condition of the vehicle air-conditioning system. To this end, a service unit for vehicle air-conditioning systems having a drainage and filling device for extracting the coolant/compressor oil mixture from the coolant circuit system of a vehicle air-conditioning system and for refilling the vehicle air-conditioning system with coolant and compressor oil, having a separation stage comprising at least one separator, a coolant compressor and a coolant weighing device, and having a vacuum pump for draining the residues of the coolant circuit system of the vehicle air-conditioning system is proposed, in which at least one pressure- and/or time-controlled switching valve block is provided for the optional direct fluid connection of the coolant circuit system to the separation stage and for the diversion of the flow connection from the coolant circuit system of the vehicle air-conditioning system via the vacuum pump to the separation stage.

PRESENTATION OF THE INVENTION

The invention is based on the object of being able to use inflammable or otherwise critical coolants, such as the coolant R-1234 yf, safely in a generic service unit for vehicle air-conditioning systems. This object is achieved by a service unit for vehicle air-conditioning systems having the features of claim 1 and a method having the features of claim 10.

Accordingly, the invention provides for a chimney-like gas collection chamber to be provided inside the service unit in a generic service unit for vehicle air-conditioning systems. The chimney-like gas collection chamber has an upper and a lower opening to the ambient atmosphere and is also sealed off from the ambient atmosphere. An active fan is provided in such a manner that ambient air can flow through the chimney-like gas collection chamber from top to bottom. This means that all the regions of the service unit which can come into contact with the gas of the coolant systematically or owing to leakages can be fluid-connected to the chimney-like gas collection chamber and sealed off from the remaining ambient atmosphere. Escaping coolant gas can thereby be kept away from unit parts which potentially form sparks. Other unit parts which are unavoidably fluid-connected to the ambient atmosphere are therefore sealed off from the chimney-like gas collection chamber.

The active fan ensures that flow passes through the chimney-like gas collection chamber from top to bottom, for which ambient air is used. This means firstly that gas exchange also takes place in less accessible regions of the chimney-like gas collection chamber. Secondly, it is thereby possible to accommodate certain electrical components in the chimney-like gas collection chamber without the risk of explosion, deflagration or inflammation in the atmosphere of the chimney-like gas collection chamber increasing. This is advantageous in particular if customary vacuum pumps are used in the air-conditioning service unit, with which the electrical unit part of the vacuum pump can come into contact with the gas to be evacuated. The active ventilation ensures that such gas constituents are conducted quickly outwards, so that more complex vacuum pump designs with complete separation of the electrical part from the gas atmosphere are unnecessary. This active ventilation can be supported further by additional second and/or third active ventilation systems.

If the atmosphere in the chimney-like gas collection chamber is heavier overall than air, the active fan can remain switched off during stoppage phases or phases when the service unit is not in use, because electrical sparks are not produced in these phases and it is therefore sufficient if the heavier gases sink inside the chimney-like gas collection chamber and exit the latter to the environment through the lower opening.

If the active fan or at least its electrically supplied component groups or where appropriate a unit controller are arranged outside the air-conditioning service unit or at least on the outer side thereof, potential ignition risks in the chimney-like gas collection chamber arising from the active fan itself can also be avoided.

The components to be used according to the invention which are mentioned above, as well as those claimed and described in the exemplary embodiments, are not subject to any special exceptional conditions in terms of their size, shape, material and technical design, so the selection criteria known in the field of application can be used without restriction.

Further details, features and advantages of the subject matter of the invention can be found in the subclaims, and in the description of the associated drawing and table below, in which an exemplary embodiment of an air-conditioning service unit is shown by way of example.

BRIEF DESCRIPTION OF THE FIGURES

In the drawing,

FIG. 2 shows the service unit for vehicle air-conditioning systems in vertical section (section along line I-I according to FIG. 3), and

FIG. 3 shows the same unit in vertical section shifted 90° (section along line according to FIG. 2)

PRESENTATION OF AN EXEMPLARY EMBODIMENT

As can be seen in the sectional diagrams of FIGS. 2 and 3, the chimney-like gas collection chamber 110 is for the most part formed by the unit walls 112, which are closed in on themselves, on the outer sides of the unit, the unit cover 114 and a funnel-shaped bottom 118 or e.g. a perforated plate (not shown) situated at the lower end of the unit. As the active fan 120, a first electrical fan is docked from the outside of the unit onto the upper opening 110A of the chimney-like gas collection chamber 110. The lower opening 110B of the chimney-like gas collection chamber 110 to the atmosphere is situated at the lower end of the funnel-shaped bottom 116, perforated plate or the like. One or a plurality of sealing walls 118 in the unit interior can seal off the chimney-like gas collection chamber 110 from holding chambers 122 for accommodating storage tanks 124A, 124B, 124C for compressor oils, additives, used circuit liquid and/or the like, which remain accessible from the outside of the unit. A fluid connection can however also exist between at least one of the holding chambers 122 and the chimney-like gas collection chamber 110, if the at least one of the holding chambers 122 is sealed off at its unit outer wall 112. The chimney-like gas collection chamber 110 is surrounded by an additional dashed line in FIGS. 2 and 3 by way of example and only for illustration purposes.

Inside the chimney-like gas collection chamber there are, in addition to a collection tank 126 for coolant, a compressor 128 and a condenser 130 and a vacuum pump 132 with an electric motor 132A and compressor part 132B, among other things. These unit parts and the rest of the air-conditioning unit 100 can interact in the manner corresponding to the prior art shown in FIG. 1.

A second fan 134 can additionally be arranged in the region of a unit wall 112 in order to ventilate the electric motor 132A of the vacuum pump 132 additionally. An opening 134A of a unit side wall 112 through which the fan is connected to the atmospheric air is provided for this. The additional air stream 134B produced by the second fan 134 flows down together with the air stream 1208 produced by the active fan 120 via the bottom opening 110B of the chimney-like gas collection chamber 110 as an aggregate air stream 140.

In order to ensure sufficient heat dissipation at the condenser 130, the latter can be connected to the external atmosphere via a third fan 136. To this end, the fan 136 is fluid-connected via a further opening 138A in the unit outer wall 112 and a ventilation duct 136C to the external atmosphere. The chimney-like gas collection chamber 110 is thereby sealed off from the external atmosphere. The air stream produced by the third fan 136 also exits the service unit 100 with the aggregate air stream 114 via the lower opening 110B of the chimney-like gas collection chamber [through] the unit bottom 116.

The third fan 136 and the electric motor of the vacuum pump and the compressor 128 are preferably connected in such a manner that they can only start up if the first fan 120 is in operation and the downward air stream in the chimney-like gas collection chamber 110 is consequently active. The second and third fans support the active ventilation of the chimney-like gas collection chamber 110 and its protective function.

LIST OF REFERENCE SYMBOLS

1 Compressor

2 Evaporator

3 Condenser

4A-C Pipelines

5 Separator

8A/B Service connections

7 Cold air blower

8 Warm air blower

9A/B Service connection connectors

10 Vehicle air-conditioning system

11A/B Pressure hoses

12 Extraction pump

13 Vacuum pump

14 Separator

15 Coolant store

15A Coolant condenser

16 Used oil tank

17A-J Weighing devices

18 Unloading device

19 Refilling system

19A Control unit with valve block

19B Control lines

19C Storage tank

19D Storage tank

19E Remote display

19F′ Metering and valve unit

19F″ Metering and valve unit

19F′″ Metering and valve unit

20 Service unit

26A Low pressure manometer

26B High pressure manometer

100 Service unit

110 Gas collection chamber

110A Upper opening

110B Lower opening

112 Side walls

114 Unit cover

116 Bottom

118 Sealing wall

120 Active fan

122 Holding chamber

124A-C Storage tank

126 Coolant tank

128 Compressor

130 Condenser

132 Vacuum pump

132A Electric motor

132B Compressor

134 Second fan

134A Opening

134B Additional air stream

136 Third fan

136A Opening

136C Ventilation duct

140 Aggregate air stream

Claims

1. A service unit for vehicle air-conditioning systems,

having a drainage device and a filling device for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system and for refilling the vehicle air-conditioning system with coolant and where necessary with compressor oil,

having at least one tank (126) for coolant and

having a vacuum pump (132) for producing an underpressure in the vehicle air-conditioning system which has been drained of coolant or coolant/compressor oil mixture for a subsequent extraction of coolant and where necessary compressor oil in the vehicle air-conditioning system to be refilled,

characterised in that

a chimney-like gas collection chamber (110) having upper and lower openings (110A, 110B) is arranged inside the service unit (100) and is otherwise sealed off from the ambient atmosphere, and

an active fan (120) is provided for the flow of ambient air through the chimney-like gas collection chamber (110) from top to bottom.

2. The service unit according to claim 1, characterised in that at least the unit parts of the active fan (120) and/or any additional active fans to which electrical voltage is applied and/or the control system thereof are arranged outside or on the outer side of the service unit.

3. The service unit according to claim 1, characterised by an additional active fan (134) for loading a vacuum pump (132) arranged inside the chimney-like gas collection chamber (110) with ambient air.

4. The service unit according to claim 1, characterised in that at least one, in particular a customary, vacuum pump (132) is used in the air-conditioning service unit, in which the electrical unit part of the vacuum pump (132) comes into contact with the gas to be evacuated.

5. The service unit according to claim 1, characterised by an additional active fan (136) for loading a condenser (130) arranged inside the chimney-like gas collection chamber (110) with ambient air.

6. The service unit according to claim 1, characterised in that the air streams of all the active fans can be conducted as an aggregate air stream (140) via a bottom exit opening (110B) of the chimney-like gas collection chamber (110).

7. The service unit according to claim 1, characterised in that additional storage tanks (124A, 124B, 124C) of the service unit are sealed off fluidically from the chimney-like gas collection chamber (110) by at least one sealing wall (118).

8. The service unit according to claim 1, characterised in that in particular all the regions of the service unit which come or can come into contact with the gas of the coolant systematically or owing to leakages are or can be fluid-connected to the chimney-like gas collection chamber and shut off from the remaining ambient atmosphere.

9. The service unit according to claim 1, characterised in that any further fans, the electric motor of any vacuum pump and/or a compressor are preferably connected in such a manner that they can generally only start up if the downward air stream in the chimney-like gas collection chamber 110 is active.

10. A method for removing the coolant or a coolant/compressor oil mixture from a vehicle air-conditioning system and for refilling the vehicle air-conditioning system with coolant and where necessary with compressor oil by means of a service unit having at least one tank for coolant and having a vacuum pump for producing an underpressure in the vehicle air-conditioning system which has been drained of coolant or coolant/compressor oil mixture for subsequent extraction of coolant and where necessary of compressor oil into the vehicle air-conditioning system to be refilled,

characterised in that

a chimney-like gas collection chamber having upper and lower openings is provided inside the service unit and is shut off from the remaining ambient atmosphere, and

ambient air flows through the chimney-like gas collection chamber from top to bottom, in particular by means of at least one active fan.

11. The method according to claim 10, characterised in that the at least one active fan for the chimney-like gas collection chamber remains switched off during stoppage phases or phases in which the service unit is not used, and the gases are left to sink downwards inside the chimney-like gas collection chamber, so that they exit the chimney-like gas collection chamber through the lower opening towards the ambient atmosphere.

12. The method according to claim 10, comprising a separation step for coolant/compressor oil mixture, characterised in that residues are drained from the coolant circuit system of the vehicle air-conditioning system by means of a vacuum pump, and the coolant circuit system is fluid-connected to a separation stage for coolant/compressor oil mixture via the vacuum pump for the purpose of recovering coolant from the residue drainage of the coolant circuit system.