EP2710236A2

EP2710236A2 - Device and method for using the waste heat of an internal combustion engine

Info

Publication number: EP2710236A2
Application number: EP12718144.4A
Authority: EP
Inventors: Michael Krueger; Gregory Rewers; Nadja Eisenmenger; Achim Brenk; Dieter Seher; Hans-Christoph Magel; Andreas Wengert
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-05-19
Filing date: 2012-04-20
Publication date: 2014-03-26
Also published as: US20140150426A1; DE102011076093A1; WO2012156175A3; WO2012156175A2

Abstract

The invention relates to a method and a device for using the waste heat of an internal combustion engine (2) comprising a thermodynamic working circuit (4) in which a working medium circulates. A pump (6), at least one heat exchanger (8) at least one expansion machine (10) and at least one capacitor (12) are arranged in the direction of flow of the working medium. The mechanical energy generated by the expansion machine (10) is selectively transferred to a drive train (23) and/or at least one other component (25) which can be driven mechanically.

Description

Description title

Device and method for using the waste heat of an internal combustion engine

The invention relates to a device and a method for using the waste heat of an internal combustion engine.

State of the art

Systems for the use of waste heat from internal combustion engines are so far only for stationary engines or large engines in use.

In such systems, the conversion of thermal energy into mechanical energy preferably takes place with the aid of an ORC process (Organic Rankine Cycle): A liquid working medium is compressed to a working pressure and conveyed to at least one heat exchanger. The waste heat from the exhaust gas or the exhaust gas recirculation is transmitted via the or the heat exchanger to the working medium of the ORC process, which is thereby evaporated. The steam is then expanded in an expansion machine, whereby mechanical energy is recovered and released. When

Expansion machines are preferably piston engines or turbines used.

From DE 10 2006 057 247 A1 a charging device is known which serves to utilize the waste heat of an internal combustion engine. At the exhaust tract of the internal combustion engine, at least one heat exchanger of a

Thermodynamic circuit attached to a working medium. In the circuit also a turbine part and a delivery unit are arranged. A compressor part arranged in the intake tract of the internal combustion engine is driven via the turbine part.

Because the supply of waste heat in mobile applications from the current

Driving condition (traffic situation, load, slope, speed, etc.) depends, it is subject to strong changes. Similarly, the need for drive power and the power requirement of the ancillary components is subject to strong fluctuations, so that the distribution of the power obtained from the steam power process on crankshaft or the drive train and ancillaries of the vehicle must be continuously adjusted to optimize the use of the thermodynamic work to allow the waste heat gained energy.

Disclosure of the invention

The object of the present invention is an apparatus and a method for improved utilization of the waste heat of an internal combustion engine

provide. The object is achieved by a device for waste heat utilization of an internal combustion engine, which is designed for driving a drive train, the device having a thermodynamic working circuit that uses the waste heat of the internal combustion engine for driving an expansion machine. The mechanical output of the

Expansion machine, which is designed for example as a drive shaft, is connected to a mechanical distributor device which is suitable for selectively transmitting the mechanical energy generated by the expansion machine in operation to the drive train and / or at least one further mechanically drivable component (accessory).

In a method according to the invention, the mechanical energy generated by the expansion engine from the waste heat of the internal combustion engine is selectively transmitted to the drive train of the internal combustion engine and / or a further mechanically drivable component (auxiliary unit).

A device according to the invention and a method according to the invention make it possible to optimally utilize the waste heat of the internal combustion engine in each operating state, since the mechanical energy transmitted to the drive train or the further component can be optimally adapted to the respective operating state. In one embodiment, the at least one further component is designed as an electrical generator. So the waste heat of the

Internal combustion engine for generating the operation, for example, a vehicle, necessary electric power can be used. By the

Using the waste heat, the internal combustion engine is not charged additionally, so that an increased fuel consumption is avoided.

In one embodiment, the at least one further component is designed as a hydraulic compressor or as a pneumatic compressor. Thus, the hydraulic or pneumatic pressure, as e.g. to operate a brake system is necessary to be generated by utilizing the waste heat of the internal combustion engine. By using the waste heat, the internal combustion engine is not charged additionally, so that an increased fuel consumption is avoided.

In one embodiment of the invention, the proportion of the mechanical energy generated by the expander machine, which is respectively transmitted to the drive train and the further component, can be varied. A variable energy transfer enables a particularly efficient use of the energy generated by the expansion machine, since the distribution of energy is always optimally adapted to the respective operating state and the energy currently required by the component. The distributor device is designed, for example, as a transfer case and in particular as a planetary gear. Here is the sun's wheel of

Planetary gear e.g. connected to the internal combustion engine, the planet carrier with the expansion machine and the ring gear with the other component. In such a construction of the distributor device as a planetary gear has a change in the load of the other component with the result that also changes the force acting on the ring gear of the planetary gear mechanical torque. This allows both the load distribution of the

Expansionsmaschine emitted energy between the other component and the drive train and the transmission ratio between the Internal combustion engine and the expansion machine can be varied continuously. Such a planetary gear mechanism therefore provides a cost-effective, reliable and reliable distributor device which allows a stepless distribution of the energy produced by the expansion engine to the drive train and at least one further component,

Is the other component an electrical generator for a

Two quadrant operation is designed, the generator can also be operated as a motor and it is possible to use the generator via the distributor device as a starting device for the expansion machine. This is particularly advantageous when it comes to the

Expansion machine is an expansion machine that does not start by itself, but must be started by a starter.

A freewheel may be provided between the transfer case and the internal combustion engine to prevent the engine from being dragged at low speed (e.g., idle) by a faster-running expander machine, consuming energy generated by the expander.

If a further component is designed as a hydraulic or pneumatic compressor, it is additionally possible to provide a pressure accumulator in order to store excess energy which is not required in a respective current operating state for driving the drive train for later use.

In an advantageous embodiment, between the expansion machine and the transfer case, a transmission or reduction gear

arranged, which is designed to convert the speed of the expansion machine to the speed of the internal combustion engine or the drive train. Also, as a transmission or reduction gear, a planetary gear can be used. In addition to the training of the other component as a generator,

Hydraulic compressor and / or pneumatic compressor are more

Variants are conceivable in which the mechanical energy delivered by the transfer case is used to drive additional auxiliary units. If the load of these ancillaries can be regulated, a variable load distribution can also be realized without a variable transfer case.

The invention is explained in more detail below with reference to the attached figures:

Figure 1 shows a schematic representation of an apparatus for

Waste heat utilization of an internal combustion engine with a thermodynamic working group.

Figure 2 shows a schematic section through a planetary gear, as it can be used as a transfer case.

1 shows a schematic representation of a device for waste heat utilization of an internal combustion engine 2 with a thermodynamic working circuit 4, in which a working medium circulates. In the thermodynamic working group 4 are in the flow direction of the working medium

Heat exchanger 8, an expansion machine 10, a capacitor 12 and a pump 6 are arranged.

The internal combustion engine 2 can be used, in particular, as an air-compressing,

self-igniting or mixture-compressing, spark-ignited internal combustion engine 2 be configured. Specifically, the device is suitable for waste heat utilization for applications in motor vehicles with a gasoline or diesel engine. However, a device according to the invention for the use of waste heat is also suitable for other applications.

The internal combustion engine 2 burns fuel to generate mechanical energy. The resulting exhaust gases are discharged via an exhaust system 21, in which a not shown in the figure 1 exhaust gas catalyst can be arranged. A line section of the exhaust system 21 is through a

Heat exchanger 8 out. Heat energy from the exhaust gases or the Exhaust gas recirculation is transmitted via the line section 21 in the heat exchanger 8 to the working medium of the thermodynamic working circuit 4, so that the working fluid is heated in the heat exchanger 8 and possibly superheated and evaporated.

The heat exchanger 8 of the thermodynamic working circuit 4 is connected via a line 26 to the expansion machine 10. The expansion machine 10 may be configured, for example, as a turbine or piston engine. Through the line 26, the heated working fluid flows to

Expansion machine 10 and drives it.

The expansion machine 10 has a drive shaft 1 1, via which the mechanical energy generated by the expansion machine 10 is output. After flowing through the expansion machine 10 is the

Working medium passed through a line 28 to a capacitor 12. The relaxed over the expansion machine 10 working medium is in

Condenser 12 cooled and possibly liquefied. The condenser 12 may be connected to a cooling circuit 20 in order to remove the heat from the working medium particularly effectively. This cooling circuit 20 may be e.g. to act the cooling circuit of the internal combustion engine 2. The working medium cooled in the condenser 12 is conveyed through the line 29 by a pump 6 into the line 24.

In line 24 is a pressure control valve 27, which serves to regulate the pressure of the working medium in the inlet to the heat exchanger 8. The

Evaporation temperature of the working medium can be regulated by means of the pressure set by the pressure control valve 27 in the inlet to the heat exchanger 8.

In addition, a bypass connection 31 can be provided parallel to the pump 6, in which a pressure relief valve 30 is located. By the pressure relief valve 30, the maximum allowable pressure of the working medium between the pump 6 and heat exchanger 8 limit.

The line 24 leads directly into the heat exchanger 8, in which the working medium is heated and optionally evaporated or superheated. Via the line 26 the heated working medium again reaches the expansion machine 10 and the working medium again flows through the thermodynamic working circuit 4.

By the pump 6 and the expansion machine 10, the passage direction of the working medium is determined by the thermodynamic working group 4.

Thus, the exhaust gases and the components of the exhaust gas recirculation of the internal combustion engine 2 through the heat exchanger 8 continuously heat energy can be withdrawn, which is discharged in the form of mechanical energy to the shaft 1 1.

As a working medium, water or another fluid, the

thermodynamic requirements are used. The

Working fluid experiences when flowing through the thermodynamic

Working group 4 thermodynamic changes of state. In the liquid phase, the working medium by the pump 6 to the pressure level for the

Evaporation brought. Subsequently, the heat energy of the exhaust gas is discharged via the heat exchanger 8 to the working medium. The working medium is isobarically evaporated and then overheated. The steam is adiabatically expanded in the expansion machine 10. This mechanical energy is obtained and transmitted to the shaft 1 1. The working medium is subsequently cooled in the condenser 12 and returned to the pump 6. In the thermodynamic working group 4 is also a bypass connection

15, which is connected in parallel to the expansion machine 10. The bypass connection 15 establishes a connection between the line 26 between the heat exchanger 8 and the expansion machine 10 and the line 28 between the expansion machine 10 and the condenser 12. In the bypass connection 15 is another

Bypass pressure control valve 16 is arranged. Instead of the other

Bypass pressure control valve 16 may also be a pressure relief valve 32 in the bypass connection 15. By opening the bypass pressure control valve 16, the working fluid can be passed to the expansion machine 10 passing directly from the heat exchanger 8 to the condenser 12, at high pressure in the working circuit 4 damage to components of the line 26 and / or

To prevent expansion machine 10. The drive shaft 1 1 of the expansion machine 10, an area 22 of the

Drive shaft of the internal combustion engine 2 and at least one more

Component 25 are connected to a transfer case 14. The

Transfer case 14 is designed in such a way that the mechanical energy output by expansion machine 10 via its drive shaft 11 can optionally be transferred to drive shaft 22, 23 or to additional component 25 in addition to the mechanical energy supplied by internal combustion engine 2. The drive shaft 22, 23 may be part of the example

Drive train of a vehicle which drives the drive wheels of the vehicle via a suitable transmission 40, a clutch 38 and a differential, not shown in the figure.

The further component 25 may be, for example, an electric generator, a hydraulic compressor or a pneumatic compressor.

In the course of the drive shaft 22, a freewheel 34 is disposed between the engine 2 and the transfer case 14 in order to prevent the expansion machine 10 at a low waste heat supply of the

Internal combustion engine 2 of the internal combustion engine 2 via the transfer case 14 "dragged" while receiving energy from the engine 2.

In the course of the drive shaft 1 1 of the expansion machine 10 is a

Translation or reduction gear 36 is provided which is adapted to the rotational speed of the drive shaft 1 1 of the expansion machine 10 to the rotational speed of the drive shaft 22 of the engine 2 and des

Drivetrain 23 adapt.

Figure 2 shows a schematic section through a planetary gear 42, as it can be used as a transfer case 14. In one embodiment, the drive shaft 22 of the engine 2 is connected to the sun gear 50 of the planetary gear 42. The expansion machine 10 acts on the planet carrier 48 of the planetary gear 42, and the further component 25 is in operative connection with the ring gear 44 of the planetary gear 42nd In such a structure, a change in the load of the component 25 results in that the mechanical torque acting on the ring gear 44 of the planetary gear 40 changes. With such a structure, by changing the load of the component 25, both the load sharing of the energy output from the expansion engine O between the component 25 and the power train 23 and the gear ratio between the engine 2 and the expansion engine 10 can be varied steplessly.

Claims

claims

1 . Device for utilizing waste heat of an internal combustion engine (2), which is designed to drive a drive train (23), the device having a thermodynamic working circuit (4) with an expansion machine (10), and wherein the device

characterized in that it comprises a distributor device (14) mechanically connected to the expansion machine (10) and adapted to selectively apply the mechanical energy delivered by the expander machine (10) to the drive train (23) or at least one other during operation to transmit mechanically driven component (25).

2. Device according to claim 1, wherein the further component (25) is an electric generator, a hydraulic compressor or a pneumatic compressor.

3. Device according to one of the preceding claims, wherein the

Distributor device (14) is designed such that the proportion of the energy to the drive train (23) and the further component (25) transmitted energy is variable.

4. Device according to one of the preceding claims, wherein the

Distributor device (14) as a transmission and preferably as a planetary gear (42) is formed.

5. Apparatus according to claim 4, wherein a crankshaft of the internal combustion engine (2) with the sun gear (50) of the planetary gear (42) is connected, the expansion machine (10) on the planet carrier (48) of the planetary gear (42) acts and the further component (25) is in operative connection with the ring gear (44) of the planetary gear (42).

6. Device according to one of the preceding claims, wherein the

Transfer case (14) is designed as a two-quadrant transmission.

7. Device according to one of the preceding claims, wherein between the internal combustion engine (2) and the transfer case (14) a freewheel (34) is arranged.

8. Device according to one of the preceding claims, wherein between the expander (10) and the transfer case (14) a Übersetzungsbzw. Reduction gear (36) is arranged.

9. Device according to one of the preceding claims, wherein the

Transfer case (14) is used as a starting device for starting the expansion machine (10).

10. A method for waste heat utilization of an internal combustion engine (2), which is designed for driving a drive train (23), with a

thermodynamic working group (4) which drives an expansion machine (10), characterized in that the mechanical energy generated by the expansion machine (10) is selectively transmitted to the drive train (23) and / or at least one further mechanically drivable component (25), wherein the proportion of energy transmitted to the drive train (23) or the further component (25) is preferably variable.