WO2014072341A2

WO2014072341A2 - Cooling system for electromechanical transducer

Info

Publication number: WO2014072341A2
Application number: PCT/EP2013/073167
Authority: WO
Inventors: Vladimir Danov; Bernd Gromoll
Original assignee: Siemens Aktiengesellschaft
Priority date: 2012-11-12
Filing date: 2013-11-06
Publication date: 2014-05-15
Also published as: WO2014072341A3; DE102012220557A1

Abstract

The invention relates to an electromechanical transducer (1), in particular for aircraft propulsion systems and vehicle drives, said transducer having at least one inlet (2) and an outlet (3) for at least one hollow conduit (4) for receiving a coolant fluid (5). The hollow conduit (4) can be situated in or on a rotor (6) and/or a stator (7) and/or a shaft (8) and/or a housing (9) of the electromechanical transducer (1) and said hollow conduit (4) is set up as an evaporator (10) for receiving thermal energy from the electromechanical transducer (1) by means of the coolant fluid (5). The cooling process allows the efficiency of the electromechanical transducer (1) to be increased and permits a more compact construction.

Description

description

Cooling for electromechanical converters The invention relates to cooling for electromechanical converters.

Electromechanical transducers have been known for some time. For example, an electric motor is such an electromechanical converter that converts electrical energy into mechanical energy. In this case, a force that is exerted by a magnetic field on current-carrying conductor of a coil, put into motion. Such electric motors are used to drive various work machines and vehicles - above all rail vehicles, trolleybuses, electric vehicles, hybrid vehicles.

In an electromechanical converter, various losses occur. The resulting power loss must be removed so that the electromechanical converter does not overheat. Last but not least, the losses as well as the permissible heating are boundary conditions for determining the size of an engine. Eddy current losses due to iron ligation iron packets, magnetization losses due to hysteresis, friction losses due to bearings and seals, etc., which cause heating of the electromechanical converter, contribute to the losses. The associated increase in temperature has a major impact on the efficiency of the electromechanical transducer. Generally, an elevated temperature automatically means a higher electrical resistance of the conductors in the windings, which in turn leads to the increase of ohmic losses in the electromechanical transducer. For the reasons mentioned above is a cooling of electric drives or

Electromechanical transducers required.

However, the previous concepts for cooling electromechanical converters still offer much room for improvement. For example, previous concepts for cooling include example, an indirect cooling, in which the housing of the electromechanical transducer is air-cooled. A disadvantage of this method is that parts of the electromechanical transducer, which are located, for example, in the middle of the electromechanical transducer, are insufficiently cooled.

In another case, it is cooled by means of an open housing. However, this results in dirt particles in the electromechanical transducer, which can lead to higher friction losses.

Recent developments use a direct water cooling of the shaft or a thermosiphon cooling. However, direct water cooling places increased demands on the design of the electromechanical transducer and is costly.

It is an object of the present invention to provide an electromechanical transducer having a compact design and having a higher efficiency compared to conventional electromechanical converters.

This object is achieved by means of an electromechanical transducer having at least one inlet and one outlet for at least one hollow conduit for receiving a cooling fluid, wherein the hollow conduit in or on a rotor and / or a stator and / or a shaft and / or a Housing of the electromechanical transducer can be arranged, and wherein the hollow conduit is arranged as an evaporator for receiving heat energy from the electromechanical transducer by means of the cooling fluid. A significant advantage is that electromechanical transducers, which are provided with hollow conductors can be cooled directly with a cooling fluid. This can be implemented particularly effectively and efficiently, for example, in electromechanical converters whose conductors of the winding are designed as small tubes. Such cooling is particularly advantageous for drives or electromechanical converters which are installed in a motor vehicle or an aircraft, since it is there in In most cases, there is already a water cooling system. In other words, the invention provides that a hollow conductor or a hollow housing and a hollow shaft of an electromechanical transducer is used as an evaporator of a heat pump. This makes it possible in a simple manner to increase the efficiency of an electric drive or an electromechanical transducer. In addition, such electromechanical transducers can be made more compact. In a preferred embodiment of the invention, the electromechanical transducer is arranged to direct, via the outlet of the conduit, the cooling fluid for compression to a compressor, which in turn supplies the cooling fluid for heat release to a condenser, from which it is subsequently routable to expand, and from the throttle again via the inlet, which acts as an evaporator hollow line of the electromechanical transducer, for receiving heat energy can be fed. In other words, the electromechanical transducer takes advantage of the characteristics of a compression refrigeration machine. In this case, the effect of the heat of evaporation is used in a change of state of aggregation of liquid to gas. The cooling fluid, which is moved in a closed circuit, experiences successively different states of aggregate state. In this case, the gaseous cooling fluid is first compressed by a compressor in this case. From the compressor, the cooling fluid is supplied to a condenser with heat release. Subsequently, the liquid cooling fluid is forwarded to a throttle for expansion, while reducing its pressure. The now expanded cooling fluid is supplied again via the inlet of the acting as an evaporator hollow line of the electromechanical transducer for receiving heat energy. The cycle described above can now start over. The process must be kept on the outside by supplying mechanical work via the compressor. In this way, the cooling fluid takes a heat output - here on acting as an evaporator hollow duct of the electromechanical transducer - at a low temperature level and then outputs the heat output with the input of mechanical work - from the compressor - at a higher temperature level to the environment. In this case, the efficiency of acting as a compression refrigeration cooling of the electromechanical transducer increases with decreasing temperatures of the environment. This is particularly true in aircraft coolers, as they are exposed to a very low ambient temperature.

In a particularly preferred embodiment of the invention, the electromechanical converter is set up such that the cooling fluid can be taken out via the outlet of the line by means of a jet pump in which a negative pressure can be generated by means of an accelerated propellant of the jet pump and thereby the expanding cooling fluid is sucked via the outlet, and wherein the sucked cooling fluid can be supplied with the driving medium from the jet pump to a condenser for cooling, from which it is then fed again via the inlet of the hollow line to the evaporator. A particular advantage of this embodiment is that no compressor, but only a comparatively simple pump is needed. In a particularly preferred embodiment, the propellant of the jet pump is an ionic liquid. Since ionic liquids have only a very low vapor pressure, it is possible to achieve with a jet pump a strong negative pressure for sucking the cooling fluid from the hollow conduit of the electromechanical transducer. This effect is used to vaporize the cooling fluid. In this case, heat is removed from the environment during the evaporation of the cooling fluid. In this way, the cooling of the electromechanical transducer is achieved.

To increase the effectiveness of the cooling, the cooling fluid is a volatile substance. This can be cooled particularly effectively and efficiently. A condenser, which is designed as a separate radiator of a vehicle or is already integrated in a radiator of a vehicle, can advantageously be used for cooling the electromechanical converter - electric drive - of the vehicle itself. As a result, space and weight can be saved in the vehicle.

In a further preferred embodiment, the capacitor of the electromechanical transducer - electric drive - is designed as a separate radiator of an aircraft or integrated in an existing radiator of an aircraft. This can be saved in the space of the aircraft and at the same weight can be reduced.

In the following the invention and exemplary embodiments will be explained in more detail with reference to a drawing.

Show it:

1 shows an electromechanical transducer with an integrated hollow conduit for cooling, according to an embodiment of the invention; 2 shows a schematic diagram of a jet pump for cooling an electromechanical transducer according to an embodiment of the invention and its implementation. In Figure 1, an electromechanical transducer 1 according to a

Embodiment of the invention shown. The electromechanical transducer 1 is formed in the embodiment shown in FIG 1 as an electric drive. Simplified while the essential components of the electromechanical transducer 1 are shown. It is a located on a shaft 8 rotor 6 which is rotatably mounted within a stator 7, wherein the individual components are accommodated in a housing 9. During operation of the electromechanical transducer 1, power losses occur which lead to heating of the individual components and thereby reduce the efficiency of the electromechanical converter 1. To counteract this, the stator 7 is provided in this embodiment with hollow lines 4, which are suitable for receiving and guiding a cooling fluid 5. In FIG. 1, for the sake of simplification, only a hollow line 4 is shown in order to illustrate the mode of operation of a cooling of the electromechanical converter 1.

In order to enable a very high and uniform cooling of the electromechanical transducer 1, the electromechanical transducer 1 according to a further embodiment of the invention in several or all components of the electromechanical transducer 1 hollow lines 4 for receiving the cooling fluid 5 have. The hollow conduit 4 has an inlet 2 and an outlet 3, through which a cooling fluid 5 is supplied to or removed from a hollow conduit 4. The hollow line 4 assumes the function of an evaporator 10 for receiving heat energy from the electromechanical transducer 1 by means of the cooling fluid 5 therein. Via the inlet 2 and the outlet 3, the hollow line 4 acting as the evaporator 10 is connected to a circuit. whose other components complement each other to form a compression refrigeration machine.

The direction of a cycle is illustrated by the arrows in FIG. 1, in which the cooling fluid 5 successively undergoes different changes of state of aggregation. The heated from the electromechanical transducer 1 in its hollow line 4 cooling fluid 5 via the outlet 3 to a compressor 11 which compresses the cooling fluid 5 - liquefied - and passes on to a condenser 12, in which the cooling fluid 5 is cooled with heat release. Subsequently, the cooling fluid 5 is expanded via a throttle 13, wherein the cooling fluid 5 is again converted into a gaseous state. In a further step, the cooled Fluid 5 again supplied via an inlet 2 of the evaporator 10 acting as hollow line 4. The cooling fluid 5 can now absorb heat energy of the electromechanical transducer 1 again. This starts the cycle described above from the beginning.

To keep the circuit running, the supply of mechanical work via the compressor 11 is necessary. The energy required for mechanical work is less than the energy obtained by the cooling of the electromechanical transducer 1.

2 shows a further embodiment of the invention, wherein in the case illustrated therein, the cooling of the cooling fluid 5 by means of a jet pump 14 takes place. 2, only the hollow line 4 acting as evaporator 10 for receiving heat energy from the electromechanical converter 1 by means of a cooling fluid 5 is shown in FIG. In this case, the jet pump 14 is a pump in which the pumping action is generated by a further fluid jet here a propellant, which sucks the coolant fluid 5 by pulse exchange another medium here, accelerated and compressed / promotes. The jet pump 14 is very simple and therefore very robust, low maintenance and versatile. In the present embodiment, an ionic liquid is used as the driving medium 15. Ionic liquids have an extremely low vapor pressure and thus allow the jet pump 14 to achieve particularly low pressures - suction pressures. The driving medium 15 is driven at very high speed by the jet pump 14, wherein in the jet pump

Negative pressure is created, which sucks in the acting as evaporator 10 hollow line 4 heated cooling fluid 5 from the hollow line 4 of the electromechanical transducer 1 and fed together with the driving medium 15 a capacitor 12. Characterized in that the cooling fluid 5 - is a volatile substance - it is sucked from the evaporator 10. The necessary for evaporation heat energy is a cooling fluid in the Evaporator 10, withdrawn with the cooling fluid or the electromechanical transducer 1 cools.

In the condenser 12, the vapor is liquefied and the resulting mixture of cooling fluid 5 and propellant medium 15 is subsequently expanded via a throttle 13. Subsequently, the mixture is supplied to the evaporator 10 again via the inlet 2. The separation of the cooling fluid 5 from the propellant medium 15 then takes place again in the evaporator 10 by evaporation. The cycle then begins again from the beginning. This type of cooling requires no compressor but only a comparatively simple pump or jet pump 14. Thus, the embodiment shown in FIG 2 allows higher cost savings during operation.

Preferably, the capacitors 12 shown in FIG. 1 and FIG. 2 are realized as part of a vehicle or aircraft. For example, a capacitor 12 may be attached to the fuselage of an aircraft and thereby cooled by the ambient air - not shown here.

In the case of a vehicle, the condenser 12 will be a vehicle radiator. In this way it is possible to cool the electromechanical transducer 1 well below an ambient temperature. The energy required for this is less significant than the savings resulting from the increase in efficiency of the electromechanical transducer 1. A possible increase in mass due to the compressor 12 can be compensated by a smaller and more compact design of the electromechanical transducer 1.

Claims

claims

1. Electromechanical converter (1), in particular for aircraft and vehicle drives, which has at least one inlet (2) and an outlet (3) for at least one hollow conduit (4) for receiving a cooling fluid (5),

wherein the hollow duct (4) can be arranged in or on a rotor (6) and / or a stator (7) and / or a shaft (8) and / or a housing (9) of the electromechanical transducer (1), and

wherein the hollow conduit (4) is arranged as an evaporator (10) for receiving heat energy from the electromechanical transducer (1) by means of the cooling fluid (5).

2. Electromechanical transducer (1) according to claim 1,

characterized in that the electromechanical transducer (1) is arranged to lead, via the outlet (3) of the conduit (4), the cooling fluid for compression to a compressor (11) which supplies the cooling fluid (5) for heat release to a capacitor (5). 12), from which it is then connected to a throttle

(13) is further conductive for expanding, and from the throttle (13) via the inlet of the evaporator (10) acting as hollow line (4) of the electromechanical transducer (1) for receiving heat energy can be supplied.

3. Electromechanical transducer (1) according to claim 1,

characterized in that

the electromechanical converter (1) is arranged to remove the cooling fluid (5) via the outlet (3) of the conduit (4) by means of a jet pump (14),

in that an underpressure can be generated by means of an accelerated propellant medium (15) of the jet pump (14) and thereby the expanding cooling fluid (5) via the outlet (3)

is sucked,

and wherein the sucked cooling fluid (5) with the driving medium

(15) from the jet pump (14) can be supplied to a condenser (12) for cooling, from which it then again over the Inlet (2) of the hollow conduit (4) to the evaporator / n (10) can be fed.

4. Electromechanical transducer (1) according to claim 3,

characterized in that the driving medium (15) of the jet pump (14) is an ionic liquid.

5. Electromechanical transducer according to one of claims 1 to 4, characterized in that the cooling fluid (5) is a volatile substance.

6. Electromechanical converter (1) according to one of claims 1 to 5, characterized in that the capacitor (12) is designed as a separate radiator of a vehicle or is integrated in a radiator of a vehicle.

7. Electromechanical converter (1) according to one of claims 1 to 5, characterized in that the capacitor (12) is designed as a separate cooler of an aircraft or is integrated in a radiator of an aircraft.