WO2008116603A2

WO2008116603A2 - Energy storage means for a land vehicle

Info

Publication number: WO2008116603A2
Application number: PCT/EP2008/002267
Authority: WO
Inventors: Andreas GRÜNDL; Bernhard Hoffmann
Original assignee: Compact Dynamics Gmbh
Priority date: 2007-03-23
Filing date: 2008-03-20
Publication date: 2008-10-02
Also published as: WO2008116603A3; DE102007014004A1

Abstract

The invention relates to energy storage means that can be arranged in a fluid-tight housing in which an electric machine having a rotor and a stator is accommodated. The stator is separated from the rotor by means of an air gap and comprises at least one stator coil. Said rotor can be surrounded by the stator. Also, the rotor can be associated with a centrifugal mass and is connected to a coolant reservoir. The coolant can reach the rotor from the coolant reservoir when the rotor rotates in order to cool said rotor. A heat exchanger can be arranged in the housing in order to cool the coolant after it has been in contact with the rotor.

Description

Energy storage for a Landfahrzeuq

description

5 Introduction

An energy storage suitable for use in a land vehicle, for example, will be described below. It may be an energy storage device for vehicles that are equipped exclusively, or in addition to an internal combustion engine, with at least one electric machine in the drive train.

10

background

In the past, the electrical energy needed in motor vehicles was generated almost entirely from fossil fuel (gasoline, natural gas or diesel). For electrically operated rail vehicles, for example, there is the concept that is released when braking.

Instead of transforming them into frictional heat, the kinetic energy is converted back into electrical (potential) energy and fed back into the supply network. By means of appropriate control devices, at least part of the braking energy is now to be reused for charging the vehicle battery (more precisely, the accumulator) in motor vehicles during braking phases. In driving situations in which electric energy is generated in excess, this electrical energy motor vehicle can be stored so that it is available in later situations to support or replace the drive energy from the internal combustion engine. In this way, about 5% -20% or more of the drive energy from the internal combustion engine can be replaced or replaced in a supportive manner for a short time (for example, for overtaking operations in road traffic).

• 5 stand. Since lead-acid batteries are heavy and have only a limited energy density, more and more types of energy storage devices are used (so-called double-layer capacitors, ultracaps, etc.). They are suitable for the short-term supply (<1 min) of energy and the covering of load peaks. However, their energy density is currently limited to about 4 - 6 Wh / kg. O

The energy storage described below may have a high energy density, and / or a long life, be constructed in a suitable manner for use in production vehicles simple manner, and / or may have a low susceptibility to error associated with a high recuperation of the energy. Kurzfassunq

The energy store can be arranged in a fluid-tight housing. The housing may also be formed by walls of other modules, for example in an internal combustion engine block. In the housing may be an electric machine with a rotor

5 and a stand to be included. The stator is separated from the rotor by an air gap and has at least one stator coil. The runner may be surrounded by the stand. But there may also be embodiments in which the runner can surround the stand. In addition, the rotor may be associated with a flywheel and be in communication with a cooling fluid reservoir, wherein from the cooling fluid reservoir

10 with rotating rotor cooling fluid can reach the rotor to cool this. A heat exchange device may be included in the housing to cool cooling fluid after it has been in contact with the rotor. However, it is also possible to provide the heat exchanger device on the outer wall of the housing. In this case, it would be beneficial if the wall of the housing provides good heat conduction.

L5

The energy storage device is suitable, for example, for a land vehicle with an electric drive, in order to store energy released in a regenerative braking by means of at least one electric machine in or on the drive train of the vehicle. In such an arrangement, the energy storage is connected to the electric machine in or on the drive train o of the vehicle, wherein the converted during braking of the vehicle in the electric machine electrical power is fed into the energy storage. The electric machine in the energy store is thereby set in rotation together with the flywheel associated flywheel. Possible speeds are between about 30,000 and 180,000 revolutions per minute and more.

>

The recuperated during braking energy must not be used to fully charge the energy storage of the motor vehicle fully. Rather, a state of charge of the energy storage for a stand consumption and startability (for example, in start-stop operation in city traffic) of the motor vehicle can be determined and adjusted depending on relevant environmental conditions. An additional charging of the energy storage can therefore take place in energetically favorable driving phases (= recuperation phases) in which no fuel would be consumed. If the energy storage would be charged in these recuperation phases on the start ability / stand-charge charge out, electrical energy is available, which can be fed directly into the electrical system without having to be applied by the (fuel-powered) generator. This excess capacity can be used to fuel otherwise. To take the generator less or no energy, which can lead to lower fuel consumption of the motor vehicle.

Through this energy storage, the potential of energy recuperation can be optimally utilized in land vehicles 5, in motor vehicles with hybrid drive, or in motor vehicles with a sufficiently sized starter generator in or on the drive train. The electric machines can win back as much energy when braking the motor vehicle. Braking requirements beyond regenerative braking can be covered by the friction brake. 0

The cooling effect caused by the cooling fluid may contribute to the rotor not excessively expanding due to heat. Such an expansion could change the air gap between the rotor and the stator. Without the cooling described, such a possible temperature-induced change in the air gap width would have to be considered in the dimensioning of the air gap. This would result in a relatively lower efficiency of the electrical machine of the energy store, since the air gap would have to be dimensioned larger for safety reasons. In contrast, the proposed embodiment of the energy accumulator allows for a smaller air gap width. This leads to a relatively higher efficiency of the electric machine of the energy store and thus o to a comparatively higher efficiency of the energy store.

In the fluid-tight housing of the energy storage, a pressure of less than 1 bar (for example, less than about 1 mbar - 200 mbar, so for example 5 mbar) prevail. In this case, all intermediate values lying between these values should also be regarded as disclosed; see. An important, resulting effect is the significantly reduced flow resistance of the rotating rotor in the vacuum environment. This results in a significantly increased energy storage capacity and a significantly lower energy loss. Thus, the entry of the cooling effect of the cooling fluid can be adjusted. As a result, an increased cooling effect can be caused in the phase transition occurring (liquid -> gaseous). The cooling of the rotating rotor is also important insofar as in a vacuum environment, the loss heat transfer through the atmosphere is reduced and the material strength of the rotor decreases with increasing temperature. The cooling increases the cycle stability and the creep strength of the arrangement appreciably.

The rotor may be associated with a pumping device for the cooling fluid, the energy required for pumping cooling fluid from the cooling fluid reservoir to the rotor (Rotary) movement of the rotor relates. This has the advantage that no separate drive for a conveyor for the cooling fluid is necessary. Furthermore, the cooling process can be determined via the amount of cooling fluid contained in the housing, since in this way the amount of cooling fluid supplied to the rotor can be limited to a certain extent. On the other 5 could be used an existing between the cooling fluid and the demand speed of the rotor assembly ^¬ hang in order to dispense with a separate regulating / controlling the cooling fluid flow to the rotor; Finally, at low rotor speed and / or short operating time, there is only a lesser need for cooling fluid. The rotor of the energy accumulator can have, at least together with at least one part of the flywheel mass, a substantially cup-shaped form with a bottom part and a substantially ring-cylindrical wall part. The annular cylindrical wall part can either have a substantially circular-cylindrical shape or a polygonal-ring-shaped form. 5

The pumping device may deliver the cooling fluid from the cooling fluid reservoir into an interior region of the substantially cup-shaped rotor.

In one variant, at least one passage can be arranged in the bottom part of the energy store, which forms a fluid connection between the cooling fluid reservoir and the inner region of the essentially cup-shaped rotor. The passage may be aligned substantially coaxially with a rotational axis of the rotor. The passage may be arranged in a central region, for example in the middle in the bottom part. In addition, the passage may be designed to face the interior of the runner

5 expanded funnel-shaped, for example. Furthermore, the passage can be designed and dimensioned such that a rotation of the rotor causes a conveying of cooling fluid from the cooling fluid reservoir into the inner region. This is caused by the fact that, due to the widening of the passage towards the inner region of the rotor, the force acting on the centrifugal force causes a component of force acting along the longitudinal axis of the passage

In another embodiment, the pumping device is designed in the manner of an Archimedean screw (also referred to as a screw conveyor or screw pump, conveyor having a threaded screw with pronounced thread surfaces) in which the Screw in the passage is arranged around the cooling fluid from the cooling fluid reservoir to the interior

; of the runner. By suitable selection (for example low-viscous and / or low-boiling hydrocarbons, which may also be halogenated), the cooling fluid may be suitable for evaporating at a region of the bottom part or at a region of the wall part and from a free opening of the cup-shaped rotor to get to the heat exchanger device.

In this case, a fluid barrier (for example in the form of a radially oriented annular collar) is provided at a free opening of the cup-shaped rotor, which prevents unevaporated fluid from leaving the interior of the rotor and to reach the heat exchanger means.

On an edge region of the pot-shaped rotor guide vanes are arranged, which are to be flowed through by the evaporated cooling fluid, so that or when this comes to the heat exchanger device. These guide vanes may be designed (for example inclined or curved) such that their side facing the interior of the rotor, as the rotor rotates, leads the side directed towards the exterior of the rotor. In this way, fluid thrown outwards from the interior of the rotor can deliver at least part of its kinetic energy to the rotor. The cooling fluid may - at the selected ambient pressure range of, for example, less than 1 bar - have a boiling point of about 40 ⁰ C - about 300 ⁰ C. All intermediate values lying between these values should also be regarded as disclosed.

The electric machine may be a switched reluctance machine whose rotor and stator are strongly grooved. The rotor can be formed from metal sheet layers which are axially layered to its axis of rotation, for example from thin FeCo metal sheet layers. Should a defect (for example, the rotor) occur, as a result of which the rapidly rotating rotor disintegrates, the thin sheet metal layers would only be able to cause limited damage.

The rotor can be supported rotatably for example by means of a fluid bearing against the housing. But there are also other storage options, such as radial roller bearings or roller bearings, ball bearings, ceramic bearings or the like., As storage of the rotor relative to the housing or the stand possible.

In addition to the heat exchanger device for the cooling fluid cooling the rotor, the stator of the energy accumulator can also have a heat exchanger device, for example liquid cooling, which at least partially passes through the stator of the energy accumulator in the form of cooling lines. Another energy storage device has a stator which is rotatably mounted relative to the housing and relative to the rotor. Thus, the stand is no (relative to the housing) stationary assembly. Rather, when the stator coil (s) of the stator and the rotor are energized, they rotate in opposite directions. Thus, the mass of the stator (which has a larger radius of rotation than the rotor) can be used for energy storage. This further increases the power density of the overall arrangement of the energy storage. Strictly speaking, this arrangement would no longer speak of a runner and a stand; Actually, these are two opposing runners, an inner and an outer runner.

The at least one stator coil can be electrically contacted in this case via a slip ring assembly.

Other features, properties, advantages and possible modifications of this energy storage will become apparent from the following description in which reference is made to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows an energy store in a schematic sectional side view.

Fig. 2 shows the energy storage in a schematic cross-sectional view.

3a-3c show the pumping device for the cooling fluid in a schematic cross-sectional view.

Fig. 4 shows a drive train of a motor vehicle with the energy storage in a schematic representation.

Fig. 5 shows a rotor of the energy storage in a schematic side sectional view.

Fig. 6 shows a further energy storage in a schematic side sectional view. Detailed description of the energy storage

In Fig. 1, an energy storage is shown, which is arranged in a closed, circular cylindrical, fluid-tight and pressure-resistant housing 10. In the housing 10, an electric machine 12 in the form of a switched reluctance machine with a rotor 14 and a stator 16 is accommodated. The details of the reluctance machine are explained below. The stator 16 is separated from the rotor 14 by an air gap 18 and has a plurality of stator coils 20 each associated with a stator tooth 16a. The rotor 14 is formed from a stack of thin iron sheet layers. The rotor 14 is surrounded by the stator 16 and has a substantially cup-shaped shape with a bottom portion 14a and a substantially annular cylindrical wall portion 14b. In addition, the rotor 14 has assigned a flywheel 22. In the example shown, this flywheel 22 is formed by the fact that the bottom part 14a and the annular cylindrical wall part 14b are made of material that is appreciably larger than would be necessary for the function of the electric machine 12. In other words, the rotor 14 in both the radial and in the axial direction 'thicker' (ie with more material) designed as it is indicated for electrical / magnetic reasons.

Furthermore, at least one passage 14 c, which forms a fluid connection between the cooling fluid reservoir 24 and an inner area 14 d of the substantially cup-shaped rotor 14, is arranged in the bottom part 14 a of the rotor 14. Through the passage 14c, the inner region 14d of the rotor 14 is in fluid communication with a cooling fluid reservoir 24. In this case, the arrangement is such that with rotating rotor 14 cooling fluid from the cooling fluid reservoir 24 reaches the rotor 14 in order to cool it.

Finally, in the housing 10 (in Fig. 1 above the electric machine 12) a

Heat exchanger device 26 is taken to cool the cooling fluid after it has been in contact with the rotor 14. In order to achieve the delivery of the fluid, the passage 14 c is arranged in a central region in the bottom part 14 a and aligned substantially coaxially to a rotational axis R of the rotor 14. In addition, the passage 14c is shaped such that it widens conically at least in sections toward the inner region 14d of the rotor 14. In this case, the minimum diameter and the maximum diameter as well as the course of the passage 14c are designed and dimensioned such that a rotation of the rotor 14 causes a conveying of cooling fluid from the cooling fluid reservoir 24 into the inner region 14d. This can be effected by centrifugal force being able to act in the passage 14c on the fluid column which widens conically at least in sections towards the inner region 14d of the rotor 14 during rotation of the rotor 14. This results in a rotationsparaboloider funnel in the fluid column whose half-parameter converted is proportional to the square of the angular velocity ω of the rotor 14. In this case, part of the cooling fluid can be lifted relative to the fluid level when the rotor is not rotating (see FIG. 3a) and leave the passage 14c in the inner region 14d of the rotor 14 (see FIG. 3b, 3c). The part of the cooling fluid thrown into the inner region 14d of the rotor 14 then lacks in the ridge column and comes from below (from below) out of the cooling fluid reservoir 24. In order for a pumping action for the cooling fluid from the cooling fluid reservoir 24 in the inner region 14 d of the rotor 14 is achieved. This situation is illustrated in FIGS. 3a, 3b, 3c, wherein in FIG. 3a the rotor 14 is shown standing still, in FIG. 3b the rotor 14 is shown rotating slowly and in FIG. 3c the rotor 14 turns rapidly Shown is 0.

Furthermore, it is ensured that the amount of cooling fluid sensed by the runner is always sufficient to adequately wet the inner wall of the runner; On the other hand, the amount of fluid in the housing is such that no fluid leaks out of the rotor.5

The speed of the rotor 14 also affects the heat development in the energy storage. In this way, the cooling of the rotor - and thus indirectly the rest of the energy storage - can be achieved. This is achieved without expensive separate, for example, electronic temperature control of a likewise not required separate pump for the Fluid0.

The re-flow of the cooling fluid is ensured by a plurality of (for example, three or four of which are shown in FIG. 1 two) channels 24 b, the radially distributed in the circumferential direction of the cooling fluid reservoir 24 radially inward and inside the passage let 14c lead.

The bottom of the housing 10 can be used almost completely as a cooling fluid reservoir 24. The rotor 14 is rotatably supported on a fluid bearing 50 against the housing 10. The fluid bearing 50 is formed by a substantially annular plate, o which has a central recess 52, in which a bearing pin 54 of the rotor 14 dips suitably. In this case, the arrangement of the fluid bearing 50 with the bearing pin 54 is below the level of the cooling fluid, so that the bearing pin 54 is rotatably supported on the annular plate or in its central recess 52 supported by a fluid film. Instead of the fluid bearing may also be a plain bearing, a rolling bearing, a ball bearing or a roller bearing,

5 are also used with ceramic sliding surfaces or rolling elements. The cooling fluid reservoir 24 extends substantially over a region which, during operation of the arrangement, is located under the rotor 14 -see FIG. 1-and is filled with cooling fluid. The cooling fluid is suitably selected, for example fluorohydrocarbon, to flow as liquid from the cooling fluid reservoir 24 through the passage 14c and vaporize at the bottom part 14a or at the wall part 14b and as vapor from a free one

Opening 14 e of the pot-shaped rotor 14 to the heat exchanger device 26 to arrive. For this purpose, the energy storage is at least partially evacuated, so that in the fluid-tight housing 10, a pressure of about 5 - 10 millibar prevails. This significantly reduces the atmospheric flow losses of the fast rotating rotor 14. The cooling fluid - A low-lo derviskoser hydrocarbon - has in this pressure, a boiling point of about 40 ⁰ C - 300 ⁰ C, for example about 150 ⁰ C. It also higher boiling (halogenated) hydrocarbons used, it being understood in that the temperature of the rotor 14 should not reach a range in which the strength of the rotor 14 is permanently impaired.

15

The cooling fluid is adapted to evaporate at a portion of the bottom portion 14a of the rotor 14 or at a portion of the wall portion 14b of the rotor 14 when the temperature of the rotor 14 reaches this temperature range during operation of the energy accumulator. The cooling fluid thus evaporated can then emerge from a free opening 14e of the cup-shaped rotor 20 (in FIG. 1, top) and reach the heat exchanger device 26. The heat exchanger device 26 is formed by a plurality along the circumference of the housing 10 arranged pipes, which are flowed through by a cooling medium. This cooling medium, for example, water or oil, dissipates the energy of the cooling fluid released on cooling / precipitation of the cooling fluid on the piping.

»5

In the stand 16 (below the heat exchanger means 26 in Fig. 1), a plurality of through holes 40 are provided along the periphery thereof in the edge region, which pass through the stator 16 in the axial direction. Cooling fluid condensed on the heat exchanger device 26 can thus drip down therefrom and reach the cooling fluid reservoir 24 o, thus making it available for renewed introduction into the rotor 14 during its rotation. In addition, also capacitor ribs may be provided on the pipes.

At a free edge region 14f (in FIG. 1 at the top) of the cup-shaped rotor 14, vanes 34 (see FIG. 2) are arranged uniformly distributed along the circumference 5 of the vaporized cooling fluid in a substantially radial outward direction (and in Rg. 1 to the top) to flow through, so that the cup-shaped rotor 14 evaporated cooling fluid to the heat exchanger device 26 passes. These guide vanes 34 are curved in such a way that their edge 34a facing the interior of the rotor 14 leads on rotation of the rotor 14 to the edge 34b directed towards the exterior of the rotor 14. In this case, the evaporated cooling fluid to the guide vanes 34 - and thus to the rotor 14 - a portion of the kinetic energy back, which has absorbed the occurred through the passage into the interior of the rotor cooling fluid when it was brought to the speed of the rotor 14. In addition, so the speed of the cooling fluid is reduced when hitting the heat exchanger device 26. This reduces / prevents erosion of the heat exchanger device 26 by high velocity impinging cooling fluid. The heat exchanger device 26 can operate very efficiently because the vaporized cooling fluid is thrown to the heat exchanger device 26.

At the free opening 14e of the cup-shaped rotor 14, a fluid barrier 14g in the form of a radially inwardly projecting annular collar 14g is provided. This annular collar 14g prevents cooling fluid which has not yet evaporated from being blown upwards and laterally from the wall part 14b of the rotating rotor 14 so as to reach the heat exchanger device 26. Rather, the annular collar 14g holds the cooling fluid on the annular cylindrical wall portion 14b until it is vaporized. Thus, the cooling fluid in / on the rotor 14 performs a phase transition from liquid to gaseous, and at the heat exchanger device 26, a phase transition from gaseous to liquid.

The stator 16 also has a heat exchanger device 40. This heat exchanger device 40 is formed by cooling channels, which pass through the stator 16 and are traversed, for example, by water or another cooling medium, in order to generate heat in the stator 16 or the stator coils 20 from the interior of the stator Dissipate housing 10, so to reduce the losses.

The energy store has an electrical machine 12, which is designed as a switched reluctance machine, the rotor 14 and stator 16 are grooved. This electric machine can have a very simple design, robust to be realized runner, which can also be designed so that it causes low magnetic losses. Furthermore, with such a machine very high speeds (up to 200,000 rpm and more) can be realized. Another aspect is the electrical / magnetic de-excitability of the switched reluctance machine. This is important for the storage capacity of the energy at low (for example magnetic) losses. The stator 16 and the rotor 14 are strongly grooved at their respective mutually facing lateral surfaces. The stator 16 and the rotor 14 each have an even number of teeth 16a and 14j, respectively. The coils 20 are exclusively in / on the stator 16 and have the form of concentrated windings. In the stator 16 thus pronounced pole teeth 16 a are present.

In order to equalize that of the torque of the switched reluctance machine, different numbers of teeth in stand 16 and rotor 14 may be provided. There are a variety of possible combinations of the stator tooth count (ZS) and Läuferzahnzahl (ZL) to choose from. Here, a combination of stator tooth number (ZS)> rotor tooth number (ZL) is preferred.

During a rotational movement of the rotor 14, the self-inductance of a stator coil 20 changes periodically between a minimum value and a maximum value. The torque at the rotor is proportional to the square of the current through the stator coils 20, i. H. the

The direction of the torque is independent of the direction of the current in the stator coils 20. The sign of the torque is dependent on the sign of the inductance change during rotation of the rotor 14. With increasing inductance is a positive torque (motor operation), with decreasing inductance, a negative torque (Genera - door operation) generated. A large change in the inductance as a function of the rotor position causes a large torque.

The switched reluctance machine is suitable for highly efficient energy conversion in a wide speed range. The rotor 14 can be produced inexpensively in relatively few manufacturing steps. The stator 16 may have salient poles 16a on which concentrated stator coils 20 may be arranged. The stator coils 20 can either be pushed on as forming coils or manufactured in a direct winding process. The resulting in the stator 16 heat loss can be well dissipate.

The kinetic energy E ^ _n to be stored in the rotor 14 and the associated flywheel mass (see FIG. 5) is to be determined approximately according to the following relationship:

E _kin = ^1/4 - ω ² ς π [hr r ₁ ⁴ + h ₂ (r ₂ ⁴ - r ₁ ⁴⁾ + y ₂ - ₂ ^• h (r ₃ ⁴ - r ₂ ^4)] where ω is the angular velocity of the rotor 14 in s ^"1 ς the density of the material (for example iron) of the rotor 14 π the constant Pi (3,14 ....) 5 hi the height of the bottom part 14a of the rotor 14 in mh ₂ the height of the annular cylindrical wall portion 14b of the rotor 14 in mr _x the inner radius of the wall part ₃ of the outer radius of the teeth 14b of the rotor in mr ₂ of the outer radius of the wall portion 14b of the rotor in mr 14j of the rotor in m 10th

Here, the circumferential length ZL of the teeth 14j of the rotor 14 is equal to the groove length NL of the groove between two adjacent teeth 14j (see FIG. 5).

15 There are two operating modes to distinguish between when operating the energy storage unit: generator operation and motor operation (see Fig. 4). During engine operation or charging operation of the energy storage, the stator coils 20 of the energy storage - controlled by an electronic Leistungsumsteuereinheit ECU - supplied with electrical current from a drive train of the motor vehicle (combustion engine 80, clutch 82, Ge-0 gear 84, differential 86, wheels 88 ) located electric machine 90 comes. This electric machine 90 is in generator mode and brakes the motor vehicle. As a result, the rotor 14 and with it the flywheel 22 of the energy storage is set in rotation.

^"5 In the generator mode or discharging of the energy store is the rotor 14 of the flywheel 22 in rotation at a high speed. Then, the stator coils 20 of the energy storage provide electrical energy. This electrical energy is - controlled by the electronic Leistungsumsteuereinheit ECU - fed into the drive train of the motor vehicle electrical machine 90. This electric machine 90 is in engine operation and drives the motor vehicle.

In Fig. 6, another embodiment of the energy storage is illustrated, with respect to FIG. 1 comparable or equivalent components provided with the same reference numerals and are not explained again below. An essential difference from the embodiment according to FIG. 6 is that the stator 16 is likewise arranged so as to be rotatable relative to the housing 10 by means of two roller bearings 48a, 48b so as to be rotatable about the axis of rotation R. The energization of the stator coil (s) 20 takes place by means of a grinding Ring assembly 50 which is disposed on the wall of the housing 10 and the stator coil (s) 20 electrically contacted. For clarity, only two contact slip rings 50a, 50b are shown; their number depends on the number of stator coils 20. In this case, the mechanical contact (for example electromagnetically) can be designed to be liftable, so that the friction losses are reduced if no electrical power is transported via the slip ring assembly 50. In this arrangement, the rotor and the "stator" rotate in opposite directions when the stator coil (s) 20 are energized, thus providing a very space efficient arrangement of an energy storage device Inductively or capacitively coupled power into the stator coil (s) 20 or from these einkop- peln.

Claims

claims

1. Energy storage, the

• in a fluid-tight housing (10) is arranged, in which • an electric machine (12) with a rotor (14) and a stator (16) is accommodated, wherein • the stator (16)

• is separated from the rotor (14) by an air gap (18) and

• at least one stator coil (20), and wherein • the rotor (14)

Surrounded by the stand (16),

• a flywheel (22) is assigned and

• with a cooling fluid reservoir (24) is in communication, wherein from the cooling fluid reservoir (24) with rotating rotor (14) cooling fluid to the runner (14) passes to cool this, and wherein

A heat exchanger means (26) is received in the housing (10) for cooling cooling fluid after it has been in contact with the rotor (14).

2. Energy storage according to claim 1, wherein in the fluid-tight housing (10), a pressure of less than 1 bar prevails.

3. Energy storage according to one of the preceding claims, wherein the rotor (14) is associated with a pumping device for the cooling fluid, for a pumping of cooling fluid from the cooling fluid reservoir (24) to the rotor (14) required energy from the movement of the Runner (14) relates.

4. Energy storage according to one of the preceding claims, wherein the rotor (14) has a substantially cup-shaped shape

• a bottom part (14a) and • a substantially annular cylindrical wall part (14b).

5. Energy storage according to the preceding claim, wherein in the bottom part (14a) at least one passage (14c) is arranged, which has a fluid connection between the cooling fluid reservoir (24) and an inner region (14d) of the substantially cup-shaped rotor (14). forms.

6. Energy storage according to the preceding claim, wherein the passage (14c) is aligned substantially coaxially with an axis of rotation of the rotor (14).

7. Energy storage according to one of the preceding two claims, wherein the passage (14c) is arranged in a central region in the bottom part (14a).

8. Energy storage according to one of the preceding three claims, wherein the passage (14c) widens towards the inner region (14d) of the rotor (14).

The energy store of any of the previous four claims, wherein the passage (14c) is configured and dimensioned such that rotation of the runner (14) causes delivery of cooling fluid from the cooling fluid reservoir (24) to the interior area (14d) ,

10. Energy storage according to one of the preceding claims, wherein the cooling fluid is suitable, at an area of the bottom part (14 a) or at a portion of the wall part

(14b) to evaporate and from a free opening (14e) of the cup-shaped rotor (14) to the heat exchanger means (26) to get.

11. Energy storage according to one of the preceding claims, wherein at a free opening (14e) of the cup-shaped rotor (14) a fluid barrier (14f is provided, the at least partially prevented yet unavailable fluid from reaching the heat exchanger means (26).

12. Energy store according to one of the preceding claims, wherein the cooling fluid is suitable, at a portion of the bottom part (14 a) or at a portion of the wall portion

13. Energy storage according to the preceding claim, wherein at an edge region (14f) of the cup-shaped rotor (14) guide vanes (34) are arranged, which evaporate from the

Cooling fluid to flow through, so that it reaches the heat exchanger device (26).

14. Energy store according to one of the preceding claims, wherein the cooling fluid has a boiling point of about 40 ⁰ C - about 300 ⁰ C.

15. Energy storage according to one of the preceding claims, wherein the electrical machine (12) is a switched reluctance machine, the rotor (14) and stator (16) are grooved.

5 16. Energy storage device according to one of the preceding claims, wherein the rotor (14) is formed of sheet metal layers.

17. Energy storage according to the preceding claim, wherein the rotor (14) made of FeCo - sheet metal layers is formed. 0

18. Energy store according to one of the preceding claims, wherein the rotor (14) by means of a sliding, rolling, or fluid bearing against the housing (10) is rotatably supported.

19. Energy store according to one of the preceding claims, wherein the stand (16) ein5 heat exchanger means (40).

20. Energy storage according to one of the preceding claims, wherein the stator (16) relative to the housing (10) and relative to the rotor (14) is rotatably mounted. 0

21. Energy storage according to the preceding claim, wherein the at least one stator coil (20) via a slip ring assembly (50) is electrically contacted.

22. Motor vehicle equipped exclusively or in addition to an internal combustion engine with at least one electric machine in the drive train, the electric

5 engine is to be switched by an electronic Leistungsumsteuereinheit (ECU) between a motor operation and a generator operation and is connected to an energy storage device according to one of the preceding claims.

23. Use of an energy store according to one of the preceding claims in an o motor vehicle, which is equipped exclusively, or in addition to an internal combustion engine, with at least one electric machine in the drive train, wherein the electric machine by an electronic Leistungsumsteuereinheit (ECU) between an engine operation and a Generator mode is to switch.