DE102012222671B4 - Device and method for using waste heat of an internal combustion engine and turbine unit for such a device - Google Patents

Abstract

The device for utilizing waste heat from an internal combustion engine comprises an evaporator 4, a turbine unit (12) which is arranged in a turbine unit (6) and is arranged inside a turbine housing (30). A start-up duct (26) for a working medium (M), which is in the form of a bypass on the turbine unit (12) and connects an inlet opening (34) to an outlet opening (36), is formed inside the turbine housing (30). In this way, reliable start-up is achieved with a compact design without additional piping effort. At the same time, this preheats the turbine unit (12) so that there is no risk of droplet erosion damaging the turbine unit (12) when switching from start-up operation to normal operation.

Description

The invention relates to a device for utilizing waste heat of an internal combustion engine, in particular of a motor vehicle, with the features of the preamble of claim 1. The invention further relates to a turbine unit for such a device and a method for using waste heat with such a device.

Such a device is known from DE 10 2007 013 817 A1 refer to. For waste heat utilization in a motor vehicle with the aid of a Rankine cycle, an expansion device is provided, which has a fixed spiral and a movable spiral in the manner of a scroll compressor. When starting the Rankine cycle, a high-pressure chamber is connected directly to a low-pressure chamber bypassing a working chamber via a bypass channel.

From the DE 10 2007 003 801 A1 is also a device for recovering electrical energy from the exhaust heat of a motor vehicle internal combustion engine refer. Here, the exhaust heat of the internal combustion engine is used with the aid of a heat exchanger for evaporating water, which is supplied as a vapor via a Laval nozzle a tangentially flowed through Pelton constant pressure turbine. This is connected to a generator for generating electrical energy.

Due to in a motor vehicle, especially in passenger cars, highly fluctuating operating conditions is for the generation of steam a widely varying waste heat available. This leads to greatly varying steam mass flows. In order to achieve the highest possible efficiency in the implementation of the energy contained in the steam in rotational energy of the turbine to be according to the unpublished at the time of application DE 10 2012 211 578 A1 the use of different inlet nozzles provided, which are combined differently depending on the currently applied mass flow and thereby each define sound levels for certain mass flow areas. The switching stages are chosen such that when switching between two switching stages, a pressure jump within the system is limited to a maximum value.

From the DE 10 2010 042 412 A1 is to take a steam turbine, in which also depending on the current load condition between different nozzles can be switched pressure-dependent. As a switching device control valves or a pinhole are provided.

In the DE 42 14 775 A1 a steam turbine is described in which a rotary valve is provided for controlling the steam flow rate.

Due to the relatively low steam capacities and steam mass flows in a vehicle, constant pressure turbines are preferably used as so-called expansion machines. In these, the fresh steam originating from the heat exchanger is usually expanded via Laval nozzles, so that the pressure energy is converted into flow energy.

Turbines, in particular constant pressure turbines are usually not designed for a liquid-permeable operation. To avoid damage to the turbine components, the turbine should therefore be reliably applied only with steam without water.

In an initially cold system, for example, when starting the engine, this leads to problems, since at this time still no sufficient steam power and steam mass flows are available.

Based on this, the present invention seeks to ensure a reliable operation of such a device and to allow the use in motor vehicles.

The object is achieved by a device having the features of claim 1. The device is used to utilize waste heat of an internal combustion engine, in particular a motor vehicle and includes an evaporator for transmitting the waste heat to a working fluid and a driven by the working fluid turbine unit. The turbine unit is part of a turbine unit and arranged within a turbine housing of the turbine unit. The turbine housing has an inlet opening and an outlet opening for the working medium, so it flows through during operation of this. It is further provided that in the interior of the turbine housing, a bypass duct for the working medium guided as a bypass past the turbine unit is arranged, which directly connects the inlet opening with the outlet opening.

The arrangement of the start-up channel creates the possibility, when starting, when only small steam mass flows are available, pass them past the actual turbine unit, until finally in the system a sufficient system pressure and a sufficient steam mass flow are available. As a result, an overall efficient protection of the turbine unit itself is achieved.

Due to the direct integration of the starting channel in the turbine unit, a particularly space-saving design is further achieved, so that such a turbine unit is particularly suitable for use in motor vehicles with tight installation conditions. The turbine unit is usually arranged on a floor assembly of the vehicle. For such a start-up channel so no external additional piping effort is required and provided. In addition to material, weight and cost savings, this also leads to simplified assembly. Another significant advantage is the fact that when you start the system, the steam is already passed through the turbine unit and thereby heats it. As a result, during the subsequent switchover from a startup operation to a normal operation in which the steam is then conducted through the turbine unit, the formation of liquid drops as a result of condensation on cold surfaces is avoided. The starting channel therefore forms a kind of heating channel.

In addition, a by-pass or safety channel formed as a bypass is furthermore arranged within the turbine housing, which connects the inlet opening to the outlet opening in a safety mode. The flow cross section of the safety channel is greater than that of the start-up channel and preferably also larger than the largest inflow cross-section of an inlet nozzle or a combination of several inlet nozzles for the turbine unit. The safety channel is used to protect the system, for example, against too high a system pressure and / or too high a vapor mass flow when exceeding a maximum permissible limit. The safety channel is therefore designed in the manner of an emergency bypass.

In a preferred embodiment, the starting channel is therefore also guided in the region or through a turbine head of the turbine unit, in which at least one inlet nozzle is arranged. By this measure, therefore, a (drop) erosion of the turbine blades is reliably avoided even over long periods of operation with a variety of starting cycles. The turbine unit generally has a rotatably mounted turbine wheel and the upstream turbine head with the inlet nozzles integrated therein. The nozzle head is designed in particular as a nozzle disk or a nozzle ring and preferably has different inlet nozzles.

Within the approach channel, a start-up aperture with a small aperture cross-section is arranged in an expedient embodiment, wherein the aperture cross-section is selected such that a predetermined start-up system pressure is generated in operation during startup. The Anfahrblende preferably has a fixed aperture cross-section. Alternatively, it would also be possible in principle to choose a variable diaphragm cross-section, but this leads to an increased constructive and tax technical effort. This embodiment is based on the consideration that when switching between the starting operation and the normal operation as possible the desired for normal operation pressure and steam conditions exist. Thus, the turbine unit is specifically designed for a minimum steam mass flow at a minimum system pressure at which the starting operation switches to normal operation. The minimum system pressure is for example in the range of a few bar, in particular in the range of 3 bar to 10 bar. The minimum vapor mass flow is, for example, in the range of 0.5 g / s to 3 g / s. The turbine unit is designed for a fixed value pair (minimum system pressure / minimum steam mass flow). Accordingly, therefore, the aperture cross section of the Anfahrbrende is designed so that at the minimum predetermined steam mass flow, for example 1 g / s to produce the minimum (input) system pressure, for example 4 bar (4 × 10 ⁵ Pa). The diaphragm cross section is therefore preferably slightly smaller than the nozzle cross section of a first, smallest inlet nozzle of the turbine unit.

Overall, therefore, the Anfahrblende is designed with its fixed aperture cross-section in zweckwienartig configuration such that at a predetermined start-up mass flow (steam mass flow) is the predetermined start-up system pressure.

If this is generally referred to as a cross-section of a flow channel or a diaphragm or a nozzle, this is to be understood as the minimum flow cross-section at a constriction.

Due to the additional arrangement of the safety channel, the turbine unit can therefore operate in three different operating conditions, namely in a start-up operation, in which steam is passed to the turbine unit, until the desired system pressure and the desired steam mass flow are present, during normal operation, in the the working medium (steam) through the turbine unit this is driving and finally in safety operation, in which the steam is bypassed at the turbine unit, for example, at too high a system pressure.

In order to switch between these different operating states, an adjustment element with at least one flow guide channel is arranged in an expedient development between the inlet opening and the turbine unit. The adjusting element is adjustable between a starting position and an operating position. In such a way that in the approach position of the flow guide the inlet opening with the start-up channel and in the operating position, the inlet opening connects with an inflow opening (inlet nozzle) of the turbine unit. The adjusting element is designed in particular as a slide element and preferably as a disk-shaped rotary slide element. In this embodiment, the Strömungsleitkanal is formed as a simple through hole in the slider element. By this measure, switching between the various operating states is made possible by a simple mechanical adjustment movement of the slider element. Changeover valves or closing valves are therefore not required and not provided.

The adjusting element is in a preferred development a fixed intermediate element of the turbine unit in the flow direction of the working medium immediately upstream, wherein a plurality of intermediate channels are formed in the intermediate element. The intermediate channels are arranged such that a first intermediate channel is a portion of the Anfahrkanals and a second intermediate channel connects the at least one Strömungsleitkanal of the adjusting element with an inlet nozzle of the turbine unit. The intermediate element is optionally integrated into a turbine head of the turbine unit, thus forms with this a monolithic component, or is upstream of the turbine head as a separate component on the turbine head.

Preferably, a plurality of such intermediate channels are formed in the intermediate element, wherein each of the inlet nozzle is assigned a separate intermediate channel in a plurality of inlet nozzles of the turbine unit. Conveniently, a further intermediate channel is additionally integrated into the intermediate element as a section of the bypass channel.

The adjusting element is in particular designed for a turbine unit as in the unpublished up to the registration date DE 10 2012 211 578 A1 is described. The turbine unit described therein has a plurality of differently shaped inlet nozzles, which are designed in particular for different mass flows and accordingly also show different flow cross sections. When switching between different switching stages in order to cover the largest possible mass flow range during operation as a result of load change reactions of the vehicle, different combination of the inlet nozzles are switched on. The individual switching stages are generally preferably designed such that when switching to the next higher switching stage, a predetermined pressure jump within the system is not exceeded, which is for example at 25% of an average system pressure.

In order to make this possible in a particularly simple and efficient manner, the adjusting element in a preferred development has a perforated pattern with a number of through holes each forming a flow guide channel. The through holes are preferably formed differently sized. Preferably, at least some of the through holes have an opening size that extends over a plurality of connection channels. As a result, there is the advantageous possibility that multiple inlet nozzles can be supplied with steam at the same time with only one through-hole.

The hole pattern is preferably selected such that successively predetermined predetermined combination of inlet nozzles are released during the successive displacement of the adjusting in the adjustment direction, each of which form successive switching stages. This is to be understood in particular as meaning that the respectively subsequently enabled nozzle combination in each case unlocks a larger (or in the opposite direction of adjustment smaller) total flow cross section of the inlet nozzles. The total flow cross-section here is understood to be the sum of the individual cross-sections of the individual activated inlet nozzles.

In an expedient embodiment closes - in the adjustment of the adjustment - directly to the last switching stage (nozzle combination) for the largest mass flow to the position in which the bypass channel is unlocked. This ensures a very fast switching from operating mode to safety mode in an emergency.

The adjustment is further positioned in appropriate embodiments in several different operating position in which different combinations of inlet nozzles are released.

In an expedient development, the adjusting element is mounted spring-loaded in the longitudinal direction of the turbine unit, so that it is reliably held in the desired setpoint position. In particular, this prevents the occurrence of leakage currents between the adjusting element and the turbine unit or the intermediate element.

Preferably, the Anfahrbrende is integrated in the adjustment or formed by the cross section of a through hole in the adjustment.

The configuration of the adjusting element, in particular also in combination with the intermediate element, as it results in particular from claims 6 to 11, is regarded as an independently inventive solution, regardless of the formation of the starting channel. The submission of a divisional application remains reserved.

• – Eine rückseitige Antriebseinheit, über die das Verstellelement verstellbar ist. Der Antriebseinheit ist üblicherweise eine Antriebswelle zugeordnet, die sich koaxial zu einer Mittenlängsachse des Turbinenaggregats in dessen Längsrichtung erstreckt und mit dem Drehschieberelement verbunden ist.
• – An die Antriebseinheit schließt sich ein insbesondere ringförmiger Einströmraum für das Arbeitsmedium an, in den die Einlassöffnung einmündet. Der Einströmraum wird mittig von der Antriebswelle durchsetzt sowie ergänzend von einem Federelement, welches auf das Drehschieberelement einwirkt.
• – An den Einströmraum schließt sich das insbesondere als Drehschieber ausgebildete Verstellelement an.
• – An das Verstellelement schließt sich das Zwischenelement mit den Zwischenkanälen an.
• – Diesem nachgelagert ist schließlich die Turbineneinheit, die selbst wiederum mehrteilig aufgebaut ist mit einem eingangsseitigen Turbinenkopf, in dem die Einströmdüsen ausgebildet sind, sowie mit dem eigentlichen insbesondere mehrkränzigen Turbinenrad.
• – An die Turbineneinheit schließt sich schließlich ein ringförmiger Ausströmraum für das Arbeitsmedium auf, in dem die Auslassöffnung angeordnet ist.

Overall, the turbine unit is designed as a compact structural unit in which individual functional units adjoin one another in the longitudinal direction. In this case, the turbine unit has an essentially cylindrical construction, wherein the individual functional units preferably adjoin each other as cylindrical sections or join each other within a substantially cylindrical turbine housing. The individual functional units usually have the same diameter. The following functional units preferably follow one another consecutively in the longitudinal direction:

• - A rear drive unit, via which the adjusting element is adjustable. The drive unit is usually associated with a drive shaft which extends coaxially to a central longitudinal axis of the turbine unit in the longitudinal direction and is connected to the rotary valve element.
• - The drive unit is followed by a particular annular inflow space for the working fluid into which the inlet opening opens. The inflow space is penetrated centrally by the drive shaft and in addition by a spring element which acts on the rotary valve element.
• - At the inflow closes the particular designed as a rotary slide adjusting.
• - To the adjusting element, the intermediate element connects to the intermediate channels.
• - This downstream is finally the turbine unit, which in turn is itself constructed in several parts with an input side turbine head, in which the inlet nozzles are formed, as well as with the actual mehrkränzigen turbine wheel.
• Finally, an annular outflow space for the working medium, in which the outlet opening is arranged, adjoins the turbine unit.

Overall, therefore, such a turbine unit is flowed through in the longitudinal direction from the inlet opening to the outlet opening. In principle, the principle described here can also be transferred to turbine units with radial flow. Inlet and outlet ports are expediently arranged as radial openings.

The object is further achieved according to the invention by a turbine unit for such a device for utilizing the waste heat of an internal combustion engine with the features of claim 13. Finally, the object is also achieved by a method for utilizing waste heat of an internal combustion engine according to claim 14.

An embodiment will be explained in more detail with reference to FIGS. These show:

1 a block diagram of a device for using waste heat of an internal combustion engine,

2 a first sectional view of a turbine unit in the operating position during a safety operation,

3 a partial representation of a second longitudinal section through the turbine unit in the operating position during the starting operation,

4 a partial representation of a third longitudinal section in the operating position during normal operation,

5 a trained as a rotary slide adjusting element (right half of the picture) together with an intermediate disc,

6 to 9 different relative positions of the rotary valve relative to the washer, the latter being shown in dashed lines and 6 the starting operation, 7 and 8th the normal operation with differently released inlet nozzles and 9 represents the safety operation.

In the figures, like-acting parts are provided with the same reference numerals.

To use the waste heat of an internal combustion engine, especially in a car, the in 1 used greatly simplified device used. In the waste heat recovery process, the so-called Rankine process is used. The installed in the motor vehicle device for waste heat use includes a pump 2 , one as a steam generator or evaporator 4 trained heat exchanger, a turbine unit 6 and a capacitor 8th , For converting the heat energy into electrical energy is the turbine unit in the embodiment 6 a generator 10 assigned, in particular with the turbine unit 6 forms a compact unit. The turbine unit 6 includes a turbine unit 12 , To control the entire device is a control unit 14 arranged.

The components pump 2 , Evaporator 4 , Turbine aggregate 6 as well as capacitor 8th be in the flow direction 16 flows through a working medium M. Due to the horizontal dashed line in the 1 becomes the separation of a high pressure part 18 from a low pressure part 20 illustrated. In the sub-area between the capacitor 8th and evaporator 4 the working medium M is liquid, whereas in the partial area between the evaporator 4 and the capacitor 8th is vaporous and is present as vapor D. In the evaporator 4 there is a heat input and a heat output via the condenser. The corresponding heat flows 22 are represented by arrows.

For the heat input is the evaporator 4 to a heat pipe 24 connected, which is traversed by a hot medium H. This hot medium H is, for example, the exhaust gas of the internal combustion engine or else a heated coolant for the internal combustion engine. In the heat conduction 24 It may therefore be directly to an exhaust pipe of the motor vehicle or to a coolant line. The evaporator 4 is accordingly shown either as exhaust and / or coolant heat exchanger. Exhaust gas and coolant are preferably used in parallel to the heat input.

The working medium M is due to the heat input in the evaporator 4 evaporates, the steam D thus obtained is the turbine unit 12 supplied in the turbine unit 12 relaxes and thus generates a mechanical power by a turbine shaft is driven. In the embodiment described here, this power is directly to the drive of the electric generator 10 used for the generation of electrical energy. This is further used in the motor vehicle and fed into the motor vehicle own electrical system and cached, for example, in an energy storage. The electrically generated power is preferably in the range of a few kW and in particular up to 5 kW. After flowing through the turbine unit forming an expansion machine 12 the steam is at low pressure and with heat release in the condenser 8th liquefied. The working fluid M is using the pump 2 circulated within the circuit described, this being the working medium M between the condenser 8th and evaporator 4 brings back to a higher pressure level.

In a motor vehicle from the waste heat technically useful to generate steam mass flows are relatively low and are in the range of a few grams of steam per second in the case of water as the working medium M. To efficiently implement this steam expansion capacity provided in the turbine unit in mechanical power is the turbine unit 12 designed in particular as a constant pressure turbine.

For safe, damage-free operation of the turbine unit 12 Ensure that it is supplied with drip-free steam, in particular with superheated steam D. This is not guaranteed when starting an internal combustion engine. Therefore, a starting channel is in addition 26 formed, which within the turbine unit 6 at the turbine unit 12 preferably guided directly adjacent to this adjacent. In addition, in the case of excessive steam mass flow, a bypass channel is additionally provided 28 also within the turbine unit 6 educated. The turbine unit 12 is basically designed for a steam mass flow range, which is to be expected in the operation of the internal combustion engine, wherein for reasons of efficiency considerations, the turbine unit is formed only for a portion of the expected steam mass flow. So it is for very small steam mass flows as well for very large steam mass flows, which may arise, for example, in a longer full-load drive, not designed. By very small mass flows of steam, for example, mass flows of less than 1 g / s are understood, which can occur, for example, at low speeds or on descents.

The structure and operation of the turbine unit 6 will be described below on the basis of 2 to 4 explained in more detail. The turbine unit 6 has a turbine housing 30 on and extends in the longitudinal direction 32 along a center axis. The turbine unit 6 and the turbine housing 30 in particular have an at least substantially circular cross-section. The turbine unit 6 will be about in the longitudinal direction 32 flows through the steam D in operation. This occurs via a circumferentially arranged inlet opening 34 and leaves after passing through several functional units, the turbine unit 6 via an outlet opening 36 , which in turn is preferably arranged on the shell side.

Inside the turbine housing 30 is a turbine unit 12 arranged, which has a fixed turbine head 40 and a turbine wheel immediately adjacent thereto 42 having. turbine head 40 and turbine wheel 42 are surrounded by a cylinder jacket-shaped, surrounding shroud. The turbine head 40 is also referred to as a turbine ring or nozzle disk and preferably has a plurality of inlet nozzles 44 on, which are formed differently with respect to their flow cross-section. The inlet nozzles 44 are preferably on the peripheral side of the turbine head 40 formed so that the flow cross section of a respective inlet nozzle 33 is formed in cooperation with the circumferential shroud. The inlet nozzles 44 are each preferably formed obliquely to the longitudinal direction and in particular helically extending as Laval nozzles.

At the turbine unit 12 it is preferably a constant pressure turbine, which may be formed in one stage or mehrkränzig. About the turbine wheel 42 a generator shaft, not shown here, of a generator for generating electrical energy is driven.

Immediately following the turbine unit 12 towards the inlet opening 34 is an intermediate element 46 arranged, which is composed in the embodiment of two sub-areas, namely an intermediate disc 46A as well as through the turbine housing 30 formed gutter 46B , The gutter 46B divides the inner volume of the turbine housing 30 in a rear inflow portion and a front, turbine-side outflow portion. In each subregion is in each case a flow annulus, namely an inflow space 48 as well as an outflow space 50 formed in each of the inlet opening 34 or outlet opening 36 lead.

The end faces of these two subspaces are each about a kind of cover flange 52 locked. The intervening, approximately cylinder jacket-shaped housing middle part is therefore considered in total considered in cross-section approximately h-shaped.

In the intermediate element are intermediate channels 54A , B, C, whose function will be explained in more detail below.

Immediately following the washer 46A is a as a rotary valve disk 56 trained adjustment arranged, which has a plurality of through holes 58 has, the flow guide channels form. The rotary valve disk 46 is by means of a spring 60 in nominal position against the washer 46A pressed. The feather 60 relies on a pin-like housing part of a drive unit 62 off, which via a drive shaft 64 with the rotary valve disk 46 connected is. About the drive unit 62 is the rotary valve disk 56 adjustable around the center axis in different turning positions. It is therefore rotatably arranged, whereas the intermediate element 46 is arranged fixed. The drive unit 62 preferably comprises an electric drive motor. The drive unit 62 has a housing with a cylindrical surface, which is connected to the turbine housing 30 approximately aligned and between the cylindrical central part of the turbine housing 30 and the end cover flange 52 is placed. The whole in 2 illustrated turbine unit 6 is thus designed very compact and has, for example, a length in the range of about 10 to 20 cm with a diameter in the range of about 5 to 15 cm.

With this turbine unit, the in 1 operate shown device in different modes of operation, namely a start-up, a normal operation and a safety operation.

For the starting operation, for example after starting the engine of the motor vehicle, is the starting channel 26 within the turbine unit 6 formed over which the steam through the turbine housing 30 through, but at the turbine unit 38 passed by. This situation is in 3 shown. The approach channel 26 consists of different parts together, namely an intermediate channel 54A in the intermediate element 46 as well as an edge channel 68 between the turbine unit 38 and the turbine housing 30 , The intermediate channel 54A as well as the edge channel 68 are doing directly on the turbine unit 12 passed along, so that it is already preheated during start-up operation. The outer wall of the turbine unit preferably forms 12 even the wall of the intermediate channel 54A for a direct heat exchange.

The section of the intermediate channel 54A in the washer 46A is as a stop 70 formed with a small flow cross-section. The cross-section of the approach panel 70 is designed such that upon reaching a predetermined mass flow of steam, a predetermined system pressure is established. This is dimensioned such that when switching between the starting operation on the normal operation as possible no pressure jump occurs, or that such a pressure jump within a predetermined maximum pressure range, for example, a maximum of 25% of an average system pressure is lower than average system pressure of the mean pressure value between a maximum and understood minimum pressure value, which are approved by the system. When using steam as the working medium this is for example about 1.5 bar. By avoiding such a pressure surge, the entire process can be operated reliably and safely.

Upon reaching this target initial system state, with the help of the control unit 14 a signal to the drive unit 62 then transmits the rotary valve disk to switch from start to normal operation 46 into a second, defined position. This is in 4 shown. In this operating position is now via a second intermediate channel 54B a flow path to a first inlet nozzle 44 unlocked, so that the steam D through the turbine unit 42 flows and the turbine wheel 42 drives.

As follows in connection with the 5 to 9 is explained, different switching stages are provided for this normal operation, being switched depending on the currently applied steam mass flow and system pressure between the various switching stages by adjusting the rotary valve element, so that different nozzle combination are acted upon. The different nozzle combinations are designed for different steam mass flows. The design is chosen such that when switching between two adjacent switching stages of the pressure jump within the system pressure is limited to a predetermined maximum value, for example, 25% of the average system pressure. The design of the nozzles and the principle of switching is in the DE 10 2012 211 578 A1 described.

In the case of excessive steam mass flow or in the case of a defective generator 10 Finally, in order to protect against overspeeding, the operating mode of the safety operation is provided, in which the steam D is in turn connected to the turbine unit 12 via the bypass channel 28 This situation is in 2 shown. How to compare with the 3 for the starting channel results, the bypass channel 28 a nearly identical course as the approach channel 26 on, with the crucial difference that the flow cross-section of the intermediate channel 54C in the area of the washer 46A not as a stop 70 is formed, but has a significantly larger flow cross-section. The flow cross section of the bypass channel 28 is generally chosen so large that this bypass channel can be used as an emergency channel at a maximum expected amount of steam. Both 2 to 4 It should be noted that the sections shown represent different sectional planes (different angular positions), with each sectional plane passing through the central longitudinal axis.

Based on 5 to 9 Switching between different switching stages using the rotary valve disc 56 and the washer 46A explains: Both discs are concentric with each other and have the same diameter. The washer 46A is stationary, whereas the rotary valve disk 56 about the center longitudinal axis is rotatable. The rotary valve disk 56 generally has several through holes 58A -C, which are designed in particular as elongated holes, in such a way that at least some of the slots 58B , C several openings of the intermediate channels 54 can cover. In the exemplary embodiment, two elongated holes extending in the circumferential direction 58B , C provided, each extending over a predetermined angle of rotation, which is about 50 ° in the embodiment. The two circumferentially oriented slots 58B , C are arranged in addition to approximately in a common slice third. Furthermore, there is a through hole extending in the radial direction 58A formed, which is approximately diametrically opposite to the other two slots 58B , C is arranged.

In the washer 46A is a the Anfahrbrende 70 forming opening for the approach channel 76 , a bypass opening 74 for connection to the bypass channel 28 and a plurality of nozzle openings D1 to D5 are formed, each with an inlet nozzle 44 the turbine unit 38 are fluidically connected. By successive rotation of the rotary valve disk 56 in the direction of rotation 76 are successively different combination of the nozzle openings D1 unlocked, so that a respective nozzle combination with steam D is acted upon. As a result, different switching stages for switching for different vapor mass flows are formed, wherein the activation of the individual combinations is selected such that in a continuous rotation in the direction of rotation 76 each adjacent switching stages are released. Adjacent switching stages are each designed for adjacent mass flow areas. The switching between the individual switching stages takes place in particular according to the following table, which in large parts from the DE 10 2012 211 578 A1 and is described there in detail, to which reference is hereby made. The nozzles indicated in the table with the numbers 1 to 5 (inlet nozzle 44 ) are associated with the nozzle openings D1 to D5. The nozzle A according to the table corresponds to the starting aperture 70

The 6 to 9 show the superimposed arrangement of the two discs 56 and 46A , 6 shows the starting position or starting position, at which the approach panel 70 is unlocked for the starting operation. This corresponds to the switching stage 0 in the above table. In the case of successive turning in the direction of rotation 76 Subsequently, the nozzle orifices D1, D2, D3 will pass through the radial through hole 58A unlocked. In 7 the release of the nozzle opening D1 is shown. To unlock combinations of multiple nozzle openings D1 to D5, the circumferentially extending slots are 58B , C provided. As can be seen from the above table is in the switching stage 4 through the slot 58B only the nozzle opening D4 unlocked. This is followed by the combination D4 + D5, D4 + D5 + D1 etc. up to the in 8th shown switching stage 8, in which all the nozzle openings D1 to D5 are unlocked. The length of the slots 58A . 58B is therefore suitably adjusted to the angular distance of the nozzle openings D1 to D5, so that this common enabling is possible. In particular, the two elongated holes extend 58B , C over the same total rotation angle as the nozzle openings D1 to D5 ( 8th ).

Finally, in a further rotation in the direction of rotation 76 the bypass opening 74 unlocked and at the same time all other openings are closed. This again takes place via the radial through hole 58A , To enable this switching sequence between the different operating modes (start-normal operation-safety operation) so are the Anfahrblende 70 as well as the bypass opening 74 arranged on a first annulus, which is radially spaced from a second annulus, on which the nozzle openings D1 to D5 are arranged.

LIST OF REFERENCE NUMBERS

2

pump

4

Evaporator

6

turbine generator

8th

capacitor

10

generator

12

turbine unit

14

control unit

16

flow direction

18

High-pressure part

20

Low-pressure part

22

heat flow

24

heat conduction

26

Anfahrkanal

28

bypass channel

30

turbine housing

32

longitudinal direction

34

inlet port

36

outlet

40

turbine head

42

turbine

44

Inlet

46

intermediate element

46A

washer

46B

gutter

48

inflow

50

outflow

52

cover flange

54A, B, C

between channels

56

Rotary valve disc

58A, B, C

Through holes

60

feather

62

drive unit

64

drive shaft

68

edge channel

70

Anfahrblende

74

Bypass opening

D1-D5

orifices

76

direction of rotation

M

working medium

D

steam

H

hot medium

Claims (14)

Device for utilizing waste heat of an internal combustion engine, in particular of a motor vehicle, with an evaporator ( 4 ) for transferring the waste heat to a working medium (M, D) and to a turbine unit which can be driven by the working medium (M, D) ( 12 ), which within a turbine housing ( 30 ) of a turbine unit ( 6 ), wherein the turbine housing ( 30 ) an inlet opening ( 34 ) and an outlet opening ( 36 ) for the working medium (M), and within the turbine housing ( 30 ) in the manner of a bypass on the turbine unit ( 12 ) passing starting channel ( 26 ) is arranged for the working medium (M, D), wherein for a starting operation, the inlet opening ( 34 ) with the outlet opening ( 36 ) via the approach channel ( 26 ) is connectable, characterized in that within the turbine housing ( 12 ) a bypass channel ( 28 ) is formed and the flow cross-section of the bypass channel ( 28 ) greater than that of the start-up channel ( 26 ), wherein for a safety operation the inlet opening ( 34 ) with the outlet opening ( 36 ) via the bypass channel ( 28 ) is connectable Apparatus according to claim 1, characterized in that the starting channel ( 26 ) on or in a turbine head ( 40 ) of the turbine unit ( 12 ) is arranged, in which an inlet nozzle ( 44 ) for flowing the working medium (M, D) into the turbine unit ( 12 ) is arranged. Device according to one of the preceding claims, characterized in that the starting channel ( 26 ) a stop ( 70 ) having a small aperture cross-section, such that a predetermined start-up system pressure is generated during operation when starting. Apparatus according to claim 3, characterized in that the Anfahrbrende ( 70 ) has a fixed aperture cross-section, which is dimensioned such that at a predetermined starting mass flow of the predetermined starting system pressure is generated. Device according to one of the preceding claims, characterized in that between the inlet opening ( 34 ) and the turbine unit ( 12 ) an adjusting element ( 56 ) with at least one flow channel ( 58 . 58A C) is arranged, which is adjustable between a starting position and an operating position, such that the flow channel ( 58 . 58A -C) the inlet opening ( 34 ) in the starting position with the Starting channel ( 26 ) and in the operating position with at least one inlet nozzle ( 44 ) of the turbine unit ( 12 ) connects. Apparatus according to claim 5, characterized in that the adjusting element ( 56 ) is designed as a slide element, in particular as a disk-shaped rotary slide element. Apparatus according to claim 5 or 6, characterized in that the adjusting element ( 56 ) an intermediate element ( 46 ), wherein in the intermediate element ( 46 ) several intermediate channels ( 54A -C) are formed, wherein a first intermediate channel ( 54A ) a portion of the approach channel ( 26 ) and a second intermediate channel ( 54B ) the at least one flow channel ( 58 ) of the adjusting element ( 56 ) with an inlet nozzle ( 44 ) connects the turbine unit. Device according to one of claims 5 to 7, characterized in that the adjusting element ( 56 ) a hole pattern with a number of in each case one flow channel ( 58 ) forming through holes ( 58A -C). Device according to one of claims 5 to 8, characterized in that the turbine unit ( 12 ) a turbine wheel ( 42 ) and this upstream a turbine head ( 40 ) with a plurality of preferably different inlet nozzles ( 44 ), and wherein the adjusting element ( 56 ) can be positioned in several operating positions in which different combinations ( 44 ) are released by inlet nozzles. Device according to one of claims 5 to 9, characterized in that the adjusting element ( 56 ) is mounted spring loaded. Device according to one of claims 5 to 10 and according to claim 3 or 4, characterized in that the flow channel ( 58 ) the approach panel ( 70 ) or forms. Device according to one of the preceding claims, characterized in that the turbine unit ( 6 ) in the longitudinal direction ( 32 ) and in the longitudinal direction ( 32 ) adjoin one another - a drive unit ( 62 ) for a motorized adjustment of the adjusting element ( 56 ), - an inflow space ( 48 ) for the working medium (M, D) with the inlet opening ( 34 ), - designed as a rotary slide adjustment ( 56 ), - an intermediate element ( 46 ) with intermediate channels ( 54A -C), - the turbine unit ( 12 ) comprising the turbine head ( 40 ) with at least one inlet nozzle ( 44 ) as well as - an outflow space ( 50 ) for the working medium (M, D) with the outlet opening ( 36 ). Turbine aggregate ( 6 ) for a device according to one of the preceding claims, with a turbine housing ( 30 ) within which a turbine unit ( 12 ) is arranged and the turbine housing ( 30 ) an inlet opening ( 34 ) and an outlet opening ( 36 ) for a working medium (M, D), wherein in the turbine housing ( 30 ) as a bypass on the turbine unit ( 12 ) is guided past the starting channel for the working medium, wherein for a starting operation, the inlet opening ( 34 ) with the outlet opening ( 36 ) via the approach channel ( 26 ) is connectable, characterized in that within the turbine housing ( 12 ) a bypass channel ( 28 ) is formed and the flow cross-section of the bypass channel ( 28 ) greater than that of the start-up channel ( 26 ), wherein for a safety operation the inlet opening ( 34 ) with the outlet opening ( 36 ) is connectable via the bypass channel. Method for utilizing waste heat of an internal combustion engine, in particular of a motor vehicle, with a device according to one of Claims 1 to 12.

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