DE102016004754A1 - Exhaust heat utilization device for a drive device of a motor vehicle, drive device and method for operating an exhaust heat utilization device - Google Patents

Abstract

The invention relates to an exhaust heat utilization device (1) for a drive device of a motor vehicle, having an exhaust gas inlet (2) and an exhaust gas outlet (3) which are in fluid communication with one another via an exhaust gas line (4), in particular through an exhaust silencer (5) a thermally connected to the exhaust pipe (4) heat storage (7). It is provided that the heat storage (7) is designed as a high-temperature heat storage and a first storage medium (8), which is present in a high-temperature heat storage housing (11), and that the high-temperature heat storage housing (11) at least partially in a second storage medium (15) Low-temperature heat accumulator (14) are arranged, wherein the low-temperature heat accumulator (14) is associated with a low-temperature heat exchanger (16) for supplying and / or removal of heat from the second storage medium (15). The invention further relates to a drive device for a motor vehicle and to a method for operating an exhaust heat utilization device (1).

Description

The invention relates to an exhaust heat utilization device for a drive device of a motor vehicle, having an exhaust gas inlet and an exhaust gas outlet, which are in fluid communication with one another, in particular by an exhaust muffler, and with a heat storage device thermally connected to the exhaust gas line. The invention further relates to a drive device and a method for operating an exhaust heat utilization device.

The drive device serves, for example, for driving the motor vehicle, insofar as it provides the provision of a torque directed to driving the motor vehicle. During the operation of the drive device, both exhaust gas and heat accumulate, the latter being at least partially discharged from the exhaust gas from the drive device. The hot exhaust gas coming from the drive device is supplied to the exhaust heat utilization device, namely through the exhaust gas inlet. Subsequently, the exhaust gas passes through the exhaust pipe to the exhaust outlet and exits through this again from the exhaust heat utilization device. Downstream of the exhaust heat utilization device, the exhaust gas can escape, for example through a tailpipe in an outdoor environment.

The exhaust heat utilization device now has the heat storage and optionally the exhaust muffler. For example, the exhaust pipe extends through the exhaust muffler for reducing noise emissions, which emanate in particular from the drive means through. The exhaust silencer is available, for example, as a front silencer or as a rear silencer. The exhaust pipe is thermally connected to the heat storage. This serves to temporarily store the heat contained in the exhaust gas. For example, the exhaust pipe passes through the heat storage through. However, it can also be connected only thermally conductive with him.

It is an object of the invention to propose an exhaust heat utilization device which has advantages over known exhaust heat utilization devices, in particular allows a more efficient use of the heat contained in the exhaust gas.

This is achieved according to the invention with an exhaust heat utilization device having the features of claim 1. It is provided that the heat storage is designed as a high-temperature heat storage and has a first storage medium, which is present in a high-temperature heat storage housing, and that the high-temperature heat storage housing are at least partially disposed in a second storage medium having low-temperature heat storage, the low-temperature heat storage a low-temperature heat exchanger for feeding and / or removal is associated with heat from the second storage medium.

The exhaust heat utilization device has so far not only a single heat storage, but rather a plurality of heat storage, namely the high-temperature heat storage and the low-temperature heat storage. While the high-temperature heat store has the first storage medium, the second storage medium is assigned to the low-temperature heat store. Preferably, the second storage medium is different from the first storage medium or has another heat storage material. In principle, however, it is conceivable that the second storage medium corresponds to the first storage medium or the two storage media have the same heat storage material or consist of this.

The difference between the two heat accumulators lies in the temperature level for which they are designed. The high-temperature heat storage is designed for the storage of heat at higher temperatures than the low-temperature heat storage. For example, therefore, the two storage media are selected such that the first storage medium is suitable for use at higher temperatures than the second storage medium.

The first storage medium is arranged in the high-temperature heat storage housing, in particular it is completely enclosed by this. Similarly, the exhaust muffler may have a muffler housing through which the exhaust pipe extends. The exhaust muffler, in particular its muffler housing and / or the high-temperature heat storage housing are now at least partially, but preferably completely, arranged in the low-temperature heat storage, in particular in a low-temperature heat storage housing of the low-temperature heat storage in which the second storage medium is present. It is therefore provided that either the high-temperature heat storage housing, the exhaust muffler or both present at least partially in the low-temperature heat storage.

With such a configuration of the exhaust heat utilization device, the use of cached heat at different temperature levels is made possible. For example, the cached in the high-temperature heat storage heat for preheating the Exhaust gas flowing through the exhaust gas are used or vice versa, the heat contained in the exhaust gas are temporarily stored in the high-temperature heat storage.

The low-temperature heat accumulator can be charged by heat emitted by the exhaust silencer and / or the high-temperature heat accumulator. Conversely, of course, the exhaust muffler and / or the high-temperature heat storage can be heated using the cached heat in the low-temperature heat storage. In addition, it is provided that the low-temperature heat accumulator is associated with the low-temperature heat exchanger. With the aid of the low-temperature heat exchanger, heat can be supplied to and / or removed from the second storage medium. The low-temperature heat exchanger is present, for example, as a tube heat exchanger, wherein a pipeline of the low-temperature heat exchanger arranged in the second storage medium, that is enclosed by this.

Such a configuration of the exhaust heat utilization device allows flexible use of the heat contained in the exhaust gas of the drive device. This is especially true if downstream of the high-temperature heat exchanger and / or the exhaust pipe and / or the exhaust muffler, an exhaust gas purification device, in particular in the form of a catalyst, for example an oxidation catalyst, is arranged. The exhaust gas purification device can be arranged in a housing of the exhaust gas heat recovery device, wherein it is fluidly present between the exhaust gas inlet, in particular the exhaust muffler, and the exhaust gas outlet of the exhaust gas heat recovery device. The exhaust gas purification device can be present at least partially integrated in the exhaust muffler, so for example, at least partially protrude into the muffler housing.

If the drive device is switched off when heat is already temporarily stored in one of the heat accumulators, in particular the high-temperature heat accumulator, the exhaust gas coming from the latter can be preheated by means of the temporarily stored heat after a restart of the drive device so that the exhaust gas purification device is brought to its operating temperature more quickly , Accordingly, the amount of pollutants discharged toward the outside environment can be significantly reduced.

A further embodiment of the invention provides that the low-temperature heat accumulator has a low-temperature heat storage housing in which the exhaust silencer and / or the high-temperature heat storage housing and the second storage medium are present. The low-temperature heat storage housing includes insofar the exhaust muffler and / or the high-temperature heat storage housing and the second storage medium completely. Also, the low-temperature heat exchanger is arranged at least partially in the low-temperature heat storage housing. The low-temperature heat storage housing has, for example, a thermal insulation, which is penetrated only by the exhaust pipe and / or connections of the low-temperature heat exchanger.

In an advantageous development of the invention, it is provided that the first storage medium is a latent storage medium and / or the second storage medium is another latent storage medium or a thermochemical storage medium, wherein the latent storage medium has a higher phase transition temperature than the further latent storage medium. As already explained above, the storage media can basically be chosen arbitrarily. Preferably, however, the latent storage medium is used as the first storage medium. For example, a metal alloy or a wax is used.

The latent storage medium preferably has a phase transition temperature which corresponds to the temperature of the exhaust gas present in the exhaust heat utilization device during stationary operation of the drive device. However, it can also be provided that the phase transition temperature is slightly lower than this exhaust gas temperature, for example based on at least 75%, at least 80%, at least 85%, at least 90% or at least 95%.

The second storage medium can likewise be in the form of a latent storage medium, which is referred to here as a further latent storage medium. Because the heat accumulators are designed for temporarily storing heat at different temperature levels, the additional latent storage medium should have a lower phase transition temperature than the latent storage medium of the high-temperature heat accumulator. Alternatively, however, as a second storage medium, a thermochemical storage medium may also be used, for example sodium acetate.

The phase transition temperature of the further latent storage medium may correspond, for example, to a cooling water temperature of an electrical machine and / or an internal combustion engine occurring during stationary operation of the drive device or may be slightly lower. For example, the phase transition temperature based on the cooling water temperature is at least 75%, at least 80%, at least 85%, at least 90% or at least 95%. If the thermochemical storage medium is used, it may be necessary to assign an actuator to it by means of which a mechanical impulse can be impressed on the storage medium. In this way, for example, a crystallization of the storage medium can be effected. The actuator may be in the form of an ultrasonic actuator, for example.

In the context of a further embodiment of the invention, it can be provided that the low-temperature heat storage has a plurality of storage areas, in each of which the second storage medium is present. Each of the storage areas is preferably associated with a partial heat exchanger of the low-temperature heat storage, so that heat can be separately supplied to each of the storage areas and / or removed. The storage areas are preferably completely separated from each other, the storage media of the storage areas are so far fluidly separated from each other.

A preferred embodiment of the invention provides that the exhaust muffler is arranged in a muffler housing, which is present outside of the high-temperature heat storage housing. The muffler housing is formed separately from the high-temperature heat storage housing and is not included by this. However, it may be provided that the high-temperature heat storage housing rests at least partially on the muffler housing, this in particular even partially encompasses. For example, the high-temperature heat storage housing is continuously applied to a long side of the muffler housing and also extends over part of the adjoining the long side short sides of the muffler housing, so that the high-temperature heat storage is a total of U-shaped.

Within the scope of a further preferred embodiment of the invention, it is provided that the exhaust muffler, in particular the muffler housing, has a heat insulation. The thermal insulation is present for example in the form of insulating wool. It can be provided that the heat insulation, in particular the insulating wool, is flowed through by the exhaust gas flowing from the exhaust gas inlet to the exhaust gas outlet, so that it effects a thermal insulation in the direction of the exhaust gas outlet or of the tail pipe.

A development of the invention provides that the exhaust pipe runs upstream of the exhaust muffler through the first storage medium, in particular has a arranged in the first storage medium high-temperature heat exchanger. The exhaust gas flowing into the exhaust-gas heat utilization device is initially guided through the high-temperature heat accumulator before it then enters the exhaust-gas silencer downstream of the high-temperature heat exchanger. Preferably, the exhaust pipe is partially embedded completely in the first storage medium. In order to improve the heat transfer between the exhaust pipe or the exhaust gas on the one hand and the first storage medium, the high-temperature heat exchanger may be provided.

To form the high-temperature heat exchanger, for example, the portion of the exhaust gas line running in the high-temperature heat accumulator may have a plurality of parallel line strands. In addition, a ribbing on the outside of the exhaust pipe or the line strands may be formed. In particular, the exhaust pipe is located as a corrugated pipe or the strands are as corrugated pipes.

A development of the invention provides that the heat transfer between the high-temperature heat storage and / or the exhaust muffler on the one hand and the second storage medium on the other hand is adjustable, in particular by means of density change in a release layer and / or by means of a switchable heat pipe. It has already been explained above that the high-temperature heat accumulator and / or the exhaust silencer are present in the second storage medium or are embedded in the second storage medium at least regionally, in particular completely. Accordingly, heat transfer between the high-temperature heat storage or the exhaust muffler and the second storage medium can occur. This heat transfer should be adjustable.

For this purpose, for example, the separation layer may be present, which separates the high-temperature heat storage and / or the exhaust muffler from the second storage medium. In the separation layer may be present a separation layer medium whose density is variable. For example, for this purpose, the pressure in the separating layer or the pressure of the separating layer medium is adjustable. Air is preferably used as the separation layer medium. Of course, however, other interface media can be used, for example, have a different, especially a higher or lower, thermal conductivity than air. Additionally or alternatively, the switchable heat pipe is provided, via which the heat transfer is released in a first switching position and interrupted in a second switching position.

Finally, it can be provided in a further embodiment of the invention that the low-temperature heat exchange has at least one fluid line extending through the second storage medium. This has already been pointed out above. The fluid line is particularly preferably embedded in the second storage medium. If there are several storage areas in the low-temperature heat store, then each of the storage areas can be assigned at least one such fluid line.

The invention further relates to a drive device for a motor vehicle, with an internal combustion engine and an exhaust heat utilization device, in particular an exhaust heat utilization device according to the above embodiments, wherein the exhaust heat utilization device connected to the internal combustion engine exhaust inlet and an exhaust outlet, via a, in particular by an exhaust muffler extending exhaust pipe with each other are in flow communication, and having a thermally connected to the exhaust pipe heat storage.

It is provided that the heat storage is designed as a high-temperature heat storage and has a first storage medium, which is present in a high-temperature heat storage housing, and that the high-temperature heat storage housing are at least partially disposed in a second storage medium having low-temperature heat storage, the low-temperature heat storage a low-temperature heat exchanger for feeding and / or removal is associated with heat from the second storage medium, which is connected to a temperature control device for an electrical machine of the drive device.

The advantages of such an embodiment of the exhaust heat utilization device or the drive device has already been pointed out. Both the drive device and the exhaust heat utilization device can be developed according to the above explanations, so that reference is made to this extent.

The exhaust heat utilization device is connected to the internal combustion engine. In particular, this is the case for their exhaust gas inlet. The exhaust gas inlet is supplied so far produced by the internal combustion engine exhaust gas. In addition to the internal combustion engine, the drive device has the electric machine. This has the temperature control, which is designed for cooling and / or heating of the electrical machine. The tempering device is connected to the low-temperature heat exchanger, for example, a heat transfer medium used in the tempering is also supplied to the low-temperature heat exchanger to deliver heat to the second storage medium or to receive from this.

Additionally or alternatively, a cooling circuit of the internal combustion engine may be connected to the low-temperature heat exchanger, so that it can be acted upon not only indirectly via the high-temperature heat exchanger with heat of the internal combustion engine, but also directly. Likewise, it may of course be provided to supply the cooling circuit heat from the low-temperature storage.

The heat stored in the exhaust heat utilization device, that is, the high-temperature heat storage and the low-temperature heat storage, for example, can be used to heat an electrical component, such as a battery, and / or a passenger compartment of the motor vehicle, especially at low outdoor temperatures.

Finally, the invention relates to a method for operating an exhaust heat utilization device, in particular an exhaust heat utilization device according to the preceding embodiments, wherein the exhaust heat utilization device is an exhaust inlet and an exhaust outlet, which are in fluid communication with one another, in particular by an exhaust muffler, and a thermally connected to the exhaust pipe having associated heat storage. It is provided that the heat storage is designed as a high-temperature heat storage and having a first storage medium, which is present in a high-temperature heat storage housing, and that the high-temperature heat storage housing are at least partially disposed in a second storage medium having low-temperature heat storage, the low-temperature heat storage a low-temperature heat exchanger for supplying and / or removal is associated with heat from the second storage medium.

Again, with regard to advantageous embodiments of the method and the exhaust gas heat utilization device, reference is made to the above statements.

During operation of the exhaust heat utilization device, it can now be provided, for example, to charge the high-temperature heat accumulator with heat from the exhaust gas coming from the drive device. Under certain conditions, in addition, the low-temperature heat storage can be charged, for example, when the temperature of the high-temperature heat storage has exceeded a certain limit and / or a temperature of Low temperature heat storage is below a threshold. The charging by means of the heat contained in the exhaust gas can be made as long as the internal combustion engine of the drive device is running.

Additionally or alternatively, it can be provided to charge the low-temperature heat storage with heat generated by the electrical machine. Again, it may be provided that the stored heat in the low-temperature heat storage is used to heat the high-temperature heat storage, especially if the temperature of the low-temperature heat storage has exceeded a limit and / or the temperature of the high-temperature heat storage is below a threshold.

The heating of the high-temperature heat accumulator via the low-temperature heat accumulator has the advantage that a radiator serving to cool the electric machine can remain deactivated as long as heat can be transferred from the low-temperature heat accumulator to the high-temperature heat accumulator. Accordingly, radiator shutters of the motor vehicle, which otherwise would have to be opened to operate the radiator, remain closed.

Both the stored in the low-temperature heat storage and in the high-temperature heat storage heat can be used for temperature control of devices connected to the low-temperature heat exchanger. For example, the drive device, in particular the internal combustion engine and / or the electric machine, can be tempered, in particular brought to their operating temperature. Additionally or alternatively, the heat for tempering a passenger compartment or an energy storage device, in particular a battery, are used.

In the low-temperature storage heat can be stored for a very long time, especially if the heat transfer between the high-temperature heat storage and / or the exhaust muffler on the one hand and the second storage medium on the other hand is set to a lower value. This value is set, for example, as soon as the temperature of the high-temperature heat accumulator falls below the temperature of the low-temperature heat accumulator, for example because the internal combustion engine is switched off.

If the internal combustion engine is subsequently deactivated again, the heat transfer can be set to a higher value, so that the exhaust gas coming from the internal combustion engine can be preheated by means of the heat temporarily stored in the low-temperature heat accumulator via the high-temperature heat accumulator. In this way - as already explained above, the efficiency of, in particular downstream of the exhaust muffler present, exhaust gas purification devices improved.

The exhaust heat utilization device can also be used to reliably cool the electric machine with entrained internal combustion engine, for example due to a downhill. Due to the entrained internal combustion engine, the exhaust pipe and thus the high-temperature heat storage is flowed through by a cold air mass flow, which deprives the high-temperature heat storage heat. If at the same time the electric machine to be cooled, the temperature of the low-temperature heat storage is too high, for example, because it is above a limit, the heat transfer between the high-temperature heat storage and the second storage medium can be set to the higher value, so that the low-temperature heat storage heat to the high-temperature heat storage which is subsequently discharged from the cold air mass flow in the direction of the outside environment.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings, without any limitation of the invention. Showing:

1 a partially sectioned view of an exhaust heat utilization device for a drive device of a motor vehicle, and

2 a partial sectional view of the exhaust heat utilization device.

The 1 shows a partial sectional view of an exhaust heat utilization device 1 for a drive device, not shown, of a motor vehicle. The exhaust heat utilization device 1 has an exhaust inlet 2 and an exhaust outlet 3 on. The exhaust inlet 2 and the exhaust outlet 3 are over an exhaust pipe 4 fluidly connected to each other through an exhaust muffler 5 runs. Downstream of the exhaust silencer 5 , So fluidly between the exhaust muffler 5 and the exhaust outlet 3 is an exhaust gas purification device 6 arranged. Preferably, the exhaust gas purification device is located 6 in the form of a catalyst, in particular an oxidation catalyst. The exhaust gas purification device 6 is optional.

The exhaust heat utilization device 1 points next to the exhaust silencer 5 a heat storage 7 on, which is designed as a high-temperature heat storage. In the heat storage 7 is a first storage medium 8th arranged through which the exhaust pipe 4 passes through. In the embodiment shown here, the exhaust pipe 4 in the area of high temperature heat storage 7 as a high-temperature heat exchanger 9 educated. For this purpose, it branches into several, flow-parallel running strands 10 of which two are recognizable here. The cable strands 10 point to their storage medium 8th facing side, so on its outside, a Oberflächenvergrößernde ribbing on.

The first storage medium 8th the high temperature heat storage 7 lies in a high-temperature heat storage housing 11 in front. This is separate to a muffler housing 12 formed, but at least partially applied to this, in particular in a region in which the exhaust pipe 4 from the high-temperature heat storage housing 11 exit and into the muffler housing 12 entry. The exhaust silencer 5 or the muffler housing 12 has at least partially a heat insulation 13 on, which is present in the embodiment shown here in the form of insulating wool. The heat insulation 13 can also be sound-absorbing, so be present as a sound-absorbing element. The insulating wool can be referred to in this case as Schalldämpfwolle.

The exhaust silencer 5 , in particular its muffler housing 12 , and the high-temperature heat storage housing 11 are at least partially in a low-temperature heat storage 14 arranged, which is a second storage medium 15 having. Preferably, the second storage medium surrounds 15 the exhaust silencer 5 and the high-temperature heat exchanger 9 or the muffler housing 12 and the high temperature heat storage housing 11 for the most part, in particular almost completely, particularly preferably with the exception of the exhaust gas inlet 2 and the exhaust outlet 3 Completely. The latter has the advantage that of the exhaust muffler 5 and / or the high temperature heat storage 11 emitted heat in the second storage medium 15 or the low-temperature heat storage 14 cached and can be made usable insofar. The low-temperature heat storage 14 is a low temperature heat exchanger 16 associated, the at least one fluid line 17 having, through the second storage medium 15 hindurchverläuft. The fluid line 17 has an inlet at the end 18 and an outlet 19 ,

It can be provided that the low-temperature heat storage 14 several storage areas 20 and 21 having. In both memory areas 20 and 21 is in each case the second storage medium 15 in front. The storage areas 20 and 21 can with regard to the storage medium 15 be fluidly separated, so do not be in fluid communication with each other. Are several storage areas 20 and 21 before, so has the low-temperature heat exchanger 16 prefers as many fluid lines 17 on how storage areas 20 and 21 available. Accordingly, there are just as many inlets 18 and outlets 19 available.

In the embodiment shown here is the first storage medium 8th a latent storage medium and used as a second storage medium, a thermochemical storage medium. For this reason, the low-temperature heat storage 14 for each of the storage areas 20 and 21 one actor each 22 assigned, by means of which a mechanical impulse to the storage medium 15 of the respective memory area 20 respectively 21 can be imprinted.

The exhaust silencer 5 and the high temperature heat storage 7 are by means of a separating layer 23 from the second storage medium 15 the low-temperature heat storage 14 separated. In the separation layer 23 may be any medium, which may be referred to as a separation layer medium, for example. For example, by changing the pressure of the separation layer medium whose density can be influenced. This in turn has an influence on the heat transfer between the high-temperature heat storage 7 and / or the exhaust muffler 5 on the one hand and the second storage medium 15 on the other hand. Accordingly, the heat transfer by the density change in the separation layer 23 be set. Additionally or alternatively, the heat transfer via at least one switchable heat pipe can be adjusted.

The low temperature heat storage 14 has a low-temperature heat storage housing 24 in which the exhaust silencer 5 , the high temperature heat storage housing 11 as well as the second storage medium 15 available. The low-temperature heat storage housing 24 is outside with a thermal insulation 25 Mistake.

The 2 shows a further partial sectional view of a portion of the exhaust heat utilization device, wherein the low-temperature heat storage 14 as well as the separating layer 23 are not shown. It can be seen that the exhaust muffler is present as a rear muffler and is designed as a reflection and / or absorption muffler.

Using the described exhaust heat utilization device 1 an extremely flexible operation of the drive device of the motor vehicle can be realized. In particular, a temperature control of drive units of the drive device, for example an internal combustion engine and / or an electric machine, can be made as required.

Claims (10)

Exhaust heat utilization device ( 1 ) for a drive device of a motor vehicle, with an exhaust gas inlet ( 2 ) and an exhaust outlet ( 3 ), in particular via an exhaust muffler ( 5 ) running, exhaust pipe ( 4 ) are in fluid communication with each other and with a thermally connected to the exhaust pipe ( 4 ) associated heat storage ( 7 ), characterized in that the heat storage ( 7 ) is designed as a high-temperature heat storage and a first storage medium ( 8th ), which in a high-temperature heat storage housing ( 11 ), and that the high-temperature heat storage housing ( 11 ) at least partially in a second storage medium ( 15 ) having low-temperature heat storage ( 14 ) are arranged, wherein the low-temperature heat storage ( 14 ) a low-temperature heat exchanger ( 16 ) for supplying and / or removing heat from the second storage medium ( 15 ) assigned. Exhaust heat utilization device according to claim 1, characterized in that the low-temperature heat storage ( 14 ) a low-temperature heat storage housing ( 24 ), in which the exhaust muffler ( 5 ) and / or the high-temperature heat storage housing ( 11 ) and the second storage medium ( 15 ) are present. Exhaust heat utilization device according to one of the preceding claims, characterized in that the first storage medium ( 8th ) a latent storage medium and / or the second storage medium ( 15 ) is a further latent storage medium or a thermochemical storage medium, wherein the latent storage medium has a higher phase transition temperature than the further latent storage medium. Exhaust heat utilization device according to one of the preceding claims, characterized in that the exhaust muffler ( 5 ) in a muffler housing ( 12 ) is arranged outside the high-temperature heat storage housing ( 9 ) is present. Exhaust heat utilization device according to one of the preceding claims, characterized in that the exhaust muffler ( 5 ), in particular the silencer housing ( 12 ), a thermal insulation ( 13 ) having. Exhaust gas utilization device according to one of the preceding claims, characterized in that the exhaust gas line ( 4 ) upstream of the exhaust muffler ( 5 ) through the first storage medium ( 8th ), in particular one in the first storage medium ( 8th ) arranged high temperature heat exchanger ( 9 ) having. Exhaust heat utilization device according to one of the preceding claims, characterized in that the heat transfer between the high-temperature heat storage ( 7 ) and / or the exhaust muffler ( 5 ) on the one hand and the second storage medium ( 15 ) is adjustable on the other hand, in particular by means of density change in a separating layer ( 23 ) and / or by means of a switchable heat pipe. Exhaust heat utilization device according to one of the preceding claims, characterized in that the low-temperature heat exchanger ( 16 ) at least one by the second storage medium ( 15 ) extending fluid line ( 17 ) having. Drive device for a motor vehicle, with an internal combustion engine and an exhaust heat utilization device ( 1 ), in particular an exhaust heat utilization device ( 1 ) according to one or more of the preceding claims, wherein the exhaust heat utilization device ( 1 ) an exhaust gas inlet connected to the internal combustion engine ( 2 ) and an exhaust outlet ( 3 ), in particular via an exhaust muffler ( 5 ) running, exhaust pipe ( 4 ) are in fluid communication with each other, and a thermal with the exhaust pipe ( 4 ) associated heat storage ( 7 ), characterized in that the heat storage ( 7 ) is designed as a high-temperature heat storage and a first storage medium ( 8th ), which in a high-temperature heat storage housing ( 11 ), and the high-temperature heat storage housing ( 11 ) at least partially in a second storage medium ( 15 ) having low-temperature heat storage ( 14 ) are arranged, wherein the low-temperature heat storage ( 14 ) at each temperature heat exchanger ( 16 ) for supplying and / or removing heat from the second storage medium ( 15 ), which is connected to a tempering device for an electrical machine of the drive device. Method for operating an exhaust heat utilization device ( 1 ), in particular an exhaust heat utilization device ( 1 ) according to one or more of the preceding claims, wherein the exhaust heat utilization device ( 1 ) an exhaust inlet ( 2 ) and an exhaust outlet ( 3 ), in particular via an exhaust muffler ( 5 ) running, exhaust pipe ( 4 ) are in fluid communication with each other, and a thermally connected to the exhaust pipe ( 4 ) associated heat storage ( 7 ), characterized in that the heat storage ( 7 ) is designed as a high-temperature heat storage and a first storage medium ( 8th ), which in a high-temperature heat storage housing ( 11 ), and that the high-temperature heat storage housing ( 9 ) at least partially in a second storage medium ( 15 ) having low-temperature heat storage ( 14 ) are arranged, wherein the low-temperature heat storage ( 14 ) a low-temperature heat exchanger ( 16 ) for supplying and / or removing heat from the second storage medium ( 15 ) assigned.

Images