Combined heat and power system

Abstract

Combined heat and power system (1) for an internal combustion engine, in particular in a motor vehicle, an assembly consisting of a pumping device (2), a generator (3) and a turbine (4) is provided, wherein the pumping device (2) and the generator (3) are driven by the turbine (4) and upstream of the pumping device (2) a condenser device (7) is provided for liquefying a gaseous working medium exiting from the turbine (4), characterized in that the generator (3) is cooled with liquid working medium originating from the condenser device (7) or from the pumping device (2).

Description

[0001] The invention relates to a combined heat and power system for an internal combustion engine, in particular in a motor vehicle, according to the preamble of claim 1. The invention also relates to a motor vehicle with such a combined heat and power system.

[0002] Combined heat and power (CHP) generation based on the Rankine cycle has long been a focus of development in the automotive industry, as it can reduce CO2 emissions and fuel consumption in particular. At the same time, such combined heat and power (CHP) allows for increased efficiency of the combustion engine, as, unlike conventional combustion engines, the engine's waste heat is not dissipated unused into the environment.

[0003] A combined heat and power system is known, for example, from JP 2007-138797 A, in which a generator arranged separately from an internal combustion engine is driven by combined heat and power, thereby generating electrical energy. Depending on the power consumption or output of the generator, however, it is necessary to cool it, which requires appropriate, sometimes complex and therefore expensive, cooling systems.

[0004] The generic DE 10 2005 051 428 A1 discloses a combined heat and power system for an internal combustion engine, particularly in a motor vehicle. It comprises an assembly comprising a pumping device, a generator, and a turbine. The pumping device and the generator are driven by the turbine, and a condenser device for liquefying a gaseous working medium exiting the turbine is provided upstream of the pumping device. The generator is cooled by a working medium flowing into the generator from a low-pressure side of the turbine.

[0005] The present invention addresses the problem of providing an improved or at least a different embodiment for a combined heat and power system of the generic type, with which, in particular, a simple cooling of a generator in a drive system operating with combined heat and power can be achieved.

[0006] This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0007] The invention is based on the general idea of ​​using a working medium required for operating a turbine to simultaneously cool a generator in a combined heat and power system. In principle, the combined heat and power system according to the invention for an internal combustion engine comprises an assembly consisting of a pumping device, a generator, and a turbine, the turbine serving to drive the pumping device and the generator. The pumping device, in turn, conveys the working medium required for operating the turbine. A condenser device is provided on the pumping device to liquefy the gaseous working medium emerging from the turbine. The generator is then cooled using liquid working medium from the condenser or pumping device, so that an external cooling system for cooling the generator is no longer necessary.At the same time, the drive system according to the invention has the great advantage that the working medium used to cool the generator is heated during this cooling process and can therefore be fed in an already preheated state to an evaporator device arranged downstream of the pump device and upstream of the turbine. In this evaporator device, the still liquid working medium is evaporated and then fed to the turbine to drive it. Due to the drive coupling of the turbine with the generator and the pump device, the latter two components are simultaneously driven via the working medium driving the turbine. In general, this means that the assembly consisting of the pump device, the generator and the turbine does not require external cooling, but can be cooled independently using the liquid working medium originating from the condenser or the pump device.This allows for particularly cost-effective combined heat and power generation, as expensive external cooling systems are eliminated. At the same time, the efficiency of the combined heat and power system according to the invention can be increased, as the working fluid used to cool the generator is heated during the cooling process, so that less additional energy is required to evaporate it.

[0008] In an advantageous development of the inventive solution, at least one cooling channel through which the working medium flows is provided in a housing of the generator. Either an output side of the condenser or an output side of the pumping device is connected in a communicating manner to the at least one cooling channel in the housing of the generator, so that the liquid working medium can cool the generator before being fed to the evaporator device and simultaneously be heated there. Furthermore, since the working medium circulates in a closed circuit, the drive system according to the invention is extremely low-maintenance and therefore cost-effective.

[0009] In a further advantageous embodiment of the inventive solution, the pumping device, the generator, and the turbine have a common drive shaft. As described in the previous paragraphs, the turbine drives both the pumping device and the generator, whereby this can be achieved either by a corresponding power coupling, e.g., by means of shafts or belts, or by arranging all three components on a common drive shaft. In this case, a complex and sometimes expensive power transmission between the turbine on the one hand and the generator or the pumping device on the other is not necessary, so that the assembly consisting of these components can be implemented more cost-effectively and with minimal installation space.

[0010] Further important features Further important features and advantages of the invention emerge from the subclaims, from the drawing and from the associated description of the figures based on the drawing.

[0011] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

[0012] A preferred embodiment of the invention is shown in the drawing and is explained in more detail in the following description.

[0013] The only Fig. 1 shows a possible embodiment of the combined heat and power system according to the invention.

[0014] According to the Fig. 1, a combined heat and power system 1 according to the invention comprises a pumping device 2, an electric generator 3 and a turbine 4. Preferably, the pumping device 2, the generator 3 and the turbine 4 are combined in a common assembly, wherein the pumping device 2 and the electric generator 3 are driven by the turbine 4. This can be achieved, for example, by arranging all three components 2, 3 and 4 on a common shaft 5. Furthermore, an evaporator device 6 and a condenser device 7 are provided in the combined heat and power system 1 according to the invention. Fig. The arrows shown in Figure 1 symbolize a cycle of a working medium.

[0015] In general, the combined heat and power system 1 according to the invention works as follows:

[0016] First, the pumping device 2 pumps a liquid working medium, e.g., water, to the evaporator device 6 located downstream. In the evaporator device 6, the working medium changes from a liquid to a gaseous state and is fed in this gaseous state to the turbine 4 to drive it. The drive of the turbine 4 simultaneously drives the pumping device 2 connected to the turbine 4 and the generator 3. After flowing through the turbine 4, the working medium enters the condenser device 7, where it condenses and is thereby converted from a gaseous to a liquid state.

[0017] Since the electrical generator 3 in particular provides a considerable amount of power, it usually needs to be cooled, which is achieved according to the invention by the working fluid. This fluid can be supplied either from the condenser device 7 via the generator 3 to the pumping device 2, as described in Fig. 1 is shown with solid arrows or first from the condenser device 7 to the pumping device 2 and from there via the electric generator 3 to the evaporator device 6, as shown in the Fig. 1 is shown with dashed arrows. A combination of the two flow paths previously presented as alternatives is also conceivable.

[0018] The combined heat and power system 1 according to the invention thus enables cooling of the generator 3 using the system's internal working fluid, without requiring an external, i.e., separate, cooling system. At the same time, the working fluid is warmed or heated by the cooling process of the generator 3, so that significantly less energy is required for its evaporation in the downstream evaporator device 6. This allows, in particular, the efficiency and energy consumption of the combined heat and power system 1 according to the invention to be reduced.

[0019] Water is typically used as the working medium, to which additives, such as a corrosion inhibitor, can of course be added if necessary. To cool the generator 3, corresponding cooling channels are provided in a housing 8 thereof, through which the working medium can flow. Since the working medium generally circulates in a closed circuit, the combined heat and power system 1 according to the invention proves to be extremely low-maintenance and thus user-friendly.

[0020] With the combined heat and power system 1 according to the invention, external cooling for the generator 3 can thus be omitted, whereby the combined heat and power system 1 can be offered more cost-effectively and, at the same time, the installation space required for such an external cooling system can be used for other purposes, which is particularly advantageous in view of the limited installation space available in modern engine compartments. The evaporator device 6 is usually supplied with energy by the waste heat of a combustion engine (not shown), so that the engine waste heat that previously dissipated unused into the environment can now be used to generate energy. The use of such a combined heat and power system 1 is conceivable, for example, in a drive system of a motor vehicle.

Claims

[1] Combined heat and power system (1) for an internal combustion engine, in particular in a motor vehicle, an assembly consisting of a pumping device (2), a generator (3) and a turbine (4) is provided, wherein the pumping device (2) and the generator (3) are driven by the turbine (4) and upstream of the pumping device (2) a condenser device (7) is provided for liquefying a gaseous working medium emerging from the turbine (4), characterized by that the generator (3) is cooled with liquid working medium originating from the condenser device (7) or from the pumping device (2). [2] Combined heat and power system according to claim 1, characterized by that the working medium is water. [3] Combined heat and power system according to claim 1 or 2, characterized by that in a housing (8) of the generator (3) at least one cooling channel is provided through which the working medium flows. [4] Combined heat and power system according to one of claims 1 to 3, characterized by that the working medium circulates in a closed circuit. [5] Combined heat and power system according to one of claims 1 to 4, characterized by that the pumping device (2), the generator (3) and the turbine (4) have a common drive shaft (5). [6] Motor vehicle with a combined heat and power system (1) according to one of claims 1 to 5.

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