WO2015024738A1

WO2015024738A1 - Internal combustion engine with an electrically driven compressor

Info

Publication number: WO2015024738A1
Application number: PCT/EP2014/066148
Authority: WO
Inventors: Nils Lindenkamp; Michael FINDEISEN
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2013-08-20
Filing date: 2014-07-28
Publication date: 2015-02-26
Also published as: DE102013216463A1; EP3036415A1

Abstract

An internal combustion engine with an electrically driven compressor (22), which is supplied with electrical energy from an on-board electrical system (24), is characterized in that the on-board electrical system (24) comprises a first electrical subsystem with a main energy store (26), a generator (28) and at least one load (30), and also comprises a second electrical subsystem which is separate or can be separated from the first electrical subsystem and has an additional energy store (36) and an electric drive motor (34) for the compressor, wherein the additional energy store (36) can be integrated into the first electrical subsystem if required, in order to charge said first electrical subsystem.

Description

description

Internal combustion engine with an electrically driven compressor

The invention relates to an internal combustion engine with an electrically driven compressor, which is supplied from an electrical system with electrical energy.

To increase the performance of internal combustion engines charging systems can be used, which provide an increase in pressure in the intake of the engine for increased filling of the combustion chambers with charge air. Often, so-called exhaust gas turbochargers are used, which consist of a turbine and a compressor connected thereto via a shaft. The turbine is integrated into the exhaust system of the internal combustion engine and is thus flowed through by the exiting an internal combustion engine of the internal combustion engine exhaust gas, which is relaxed and transmits part of its flow energy to the turbine. This leads to a rotational movement of a rotor of the turbine, which is transmitted via a shaft to the compressor. The compressor is in the charge air system of

Integrated internal combustion engine and ensures a compression of the internal combustion engine of the engine supplied charge air.

A principal feature of exhaust gas turbochargers is that they require a sufficiently large exhaust gas mass flow for their function, without the relevant

Verdichtungsleistung and thus not the desired performance increase of

Internal combustion engine can be achieved. If, for example, an operating point of the internal combustion engine in which the latter is operated with a low load and low rotational speeds and thus also with a low exhaust gas mass flow suddenly requires a high load, then some work cycles pass before the larger exhaust gas flow generated by the increased load Exhaust gas turbocharger has accelerated, thereby providing the desired compaction performance. This delay in power delivery is considered disadvantageous and is often referred to as a "turbo lag".

To avoid the formation of a turbo lag as possible, it may be provided to combine an exhaust gas turbocharger with an electrically driven compressor. The main advantage of an electrically driven compressor lies in the possibility of operating it independently of the respective operating state of the internal combustion engine. It can thus be provided to operate the electrically driven compressor with relatively high power in an operating state of the internal combustion engine in which it is operated with low load and low speeds and thus with a low exhaust gas flow. The electrically driven compressor can then due to the small Compensate exhaust gas mass flow existing power shortfall of the exhaust gas turbocharger. A corresponding internal combustion engine is known for example from DE 101 59 801 A1.

Such, an exhaust gas turbocharger and an electrically driven compressor

However, combining internal combustion engines have so far no input into the

Series production of motor vehicles found. This is due, in particular, to the fact that the electrically driven compressor generally has to be very powerful in order to be meaningfully combined with the exhaust gas turbocharger. For this purpose, it is necessary that this within a very short period of time sufficient compressor power

can provide. The integration of an electrically driven compressor in the existing in passenger cars, operated with an electrical voltage of 12 volts electrical system is associated with a lot of effort. For this purpose, an additional electrical energy storage is necessary, which is able to provide short-term high electrical power for at least a short period of time. A supply of the electrically driven compressor from the vehicle battery or the generator is not possible due to the high current levels required. The integration of such an additional energy storage in the electrical system is a challenge. In particular, the achievement of a good stability of the electrical system during operation of the electrically driven compressor is necessary. In addition, the interpretation of the additional

Energy storage problematic, as this is also a multiple, short-term

must allow successive use of the electrically driven compressor. At the same time, overdimensioning for cost and space reasons should be avoided.

DE 10 2007 029 479 A1 discloses an electrical system for a motor vehicle, comprising at least one starter for an internal combustion engine, a generator for generating electrical energy, a vehicle battery for supplying the starter with electrical energy for starting the internal combustion engine and one or more consumers, e.g. includes a car radio. In order to prevent that in the realization of an automatic start / stop function for the internal combustion engine to a short-term switching off the consumer due to the voltage drop occurring when starting the internal combustion engine, in the electrical system is still an auxiliary voltage source, e.g. a relatively small accumulator or a capacitor integrated. In the case of a warm start of the internal combustion engine, the consumers are briefly supplied by the auxiliary voltage source with electrical energy. By decoupling a starter and the vehicle battery part of the vehicle electrical system from the remaining part is avoided that the high current flow through the starter to a

Harming consumers' energy supplies. From DE 10 2004 016 292 A1 it is known to variably interconnect an energy store from which the starter for an internal combustion engine of a motor vehicle is supplied with electrical energy and which comprises at least one accumulator and one capacitor.

In particular, it should be provided to provide the starter primarily by the capacitor with energy, which is supported by the accumulator when the charge level is too low.

WO 2008/125552 A1 discloses a supercharged by means of an exhaust gas turbocharger

Internal combustion engine. However, no mechanical connection between the turbine and the compressor of the exhaust gas turbocharger is provided. Rather, the power of the turbine is converted by means of a generator into electrical power, which is used to supply the electric motor driven compressor. An electrical energy store is used for temporary storage of electrical energy, so that operation of the compressor within limits is possible regardless of the current performance of the turbine.

DE 10 201 1 109 709 A1 discloses a vehicle electrical system for a motor vehicle with two energy storage devices connected in parallel. To high balancing currents at large

To avoid voltage differences between the two energy storage is

provided to temporarily separate the energy storage device with the lower voltage from the electrical system. Specifically, it is disclosed for a hybrid vehicle or a motor vehicle with automatic start-stop system that the relatively frequently used starter of the internal combustion engine is powered by a first of the energy storage, wherein the voltage drop of the first energy storage occurring at the start by the temporary separation of the first energy storage of the Electrical system is kept away.

Based on this prior art, the present invention seeks to provide a way, an electrically driven compressor advantageously in a

Internal combustion engine to integrate.

This object is solved by the subject matter of the independent claim.

Advantageous embodiments of the internal combustion engine according to the invention are the subject of the dependent claims and will become apparent from the following description of the invention.

A generic internal combustion engine with an electrically driven compressor, which is supplied from an electrical system with electrical energy, according to the invention further developed in that the electrical system, a first subnet with a main energy storage, a generator and at least one consumer (e.g., multimedia system, seat heating,

Vehicle lighting, etc.) as well as a separate from the first subnet or separable second subnet with at least one additional energy storage and an electrical Includes drive motor for the compressor, wherein the additional energy storage is, if necessary, integrated into the first subnet to charge this.

Here, a "separation" of the two subnetwork means that a current flow caused by the main energy store and / or the generator is prevented by the drive motor for the compressor (and the additional energy storage, as long as it is not integrated into the first subnetwork) Also be provided that the drive motor for the compressor is temporarily electrically conductively integrated into the first subnet, a current flow through this but in another way, for example by deactivation of the drive motor, is prevented.

Due to the separation according to the invention can be achieved that the drive motor of the compressor is operated by means of the second subnet, without this with large

Balancing currents in the first subnet and thus a voltage drop of

Main energy storage would go along. For recharging the additional energy storage, in particular by means of the generator, possibly also by means of the main energy storage, the additional energy storage is temporarily integrated (in non-operation of the drive motor for the compressor) in the first subnet.

According to the invention from the terms "main energy storage" and

"Additional energy storage" no limitation in terms of performance (in particular capacity and operating voltage range) of these energy storage, especially not in relation to each other, deductible.

In particular, the main energy store may be a vehicle battery, which is usually used in vehicles for supplying the vehicle electrical system and in particular can provide an operating voltage of 12 or 24 volts. The supplemental energy storage is preferably an energy storage capable of providing a high level of electrical power in the short term for at least a short period of time (e.g., <1 second to about 4 seconds). Particularly preferably, the

Additional energy storage one or more capacitors (in particular in an embodiment as a supercapacitor) include.

When using a single additional energy storage, which is integrated into the first subnetwork for charging when the compressor drive is disabled, its design and / or the choice of a suitable charging strategy may be difficult to supply the supply

Compressor drive even with several short-term successive uses of

To ensure compressor. This is in particular due to the fact that the

Additional energy storage during the enabled by this operation of the compressor is not loaded from the generator and / or the main energy storage, but charging only can be done after switching off the electrically driven compressor and then taking place integration into the first subnet. Unless the driver has one with one

motor vehicle according to the invention provided a driving behavior that temporarily makes a very frequent and short successive use of the electrically driven compressor required (eg acceleration under (near) full load from a stand to a high speed of the motor vehicle), this can only be realized if the charging capacity of the additional energy storage is correspondingly large.

Preferably, therefore, especially if only a single additional energy storage device is to be used, it is provided that it has a charge capacity corresponding to a multiple (in particular at least twice, particularly preferably at least three times) the maximum energy requirement, the "maximum energy requirement" for a is defined as the one-time use of the intermittently driven compressor and results from the (maximum) power of the compressor drive and the longest intended switch-on duration

Internal combustion engine and the size of the requested load jump to be dependent and stored in particular in an engine control of the internal combustion engine.

The dimensioning of the additional energy storage is in this case thus at a

Limit load, which is oversized for most travel profiles. This can be detrimental to the cost of the additional energy storage and the space occupied by this.

To avoid this, it can be provided in a preferred embodiment of the internal combustion engine according to the invention that a first additional energy storage and a second additional energy storage and a switching device are provided, wherein the

Switching device integrated in a first switching position the first additional energy storage in the first subnet and the second additional energy storage in the second subnet and integrated in a second switching position the second additional energy storage in the first subnet and the first additional energy storage in the second subnet. It can be particularly preferably provided that the additional energy storage at least (and particularly preferably substantially as exactly as possible) a maximum energy requirement corresponding

Have charging capacity.

This embodiment of the internal combustion engine according to the invention allows charging of the additional energy storage even during operation of the electrically driven

Compressor, which is thereby supplied by the other additional energy storage with electrical energy. Since thus also in an operation of the internal combustion engine with frequent and short successive use of the electrically driven compressor largely continuous charging of the additional energy storage is achieved, they can be relatively small, ie in total smaller than a single additional energy storage, dimensioned. In addition, the number of charge-discharge cycles for each additional energy storage reduces (halves) compared to the use of a single

Additional energy storage and thus also their capacity losses over time.

The invention will be described below with reference to the drawings

Embodiments explained in more detail. In the drawings shows:

1 shows an embodiment of an internal combustion engine according to the invention in one

schematic representation;

2 shows a schematic representation of a first embodiment of a vehicle electrical system for the internal combustion engine according to FIG. 1;

3 shows a schematic representation of a second embodiment of a vehicle electrical system for the internal combustion engine according to FIG. 1 in a first switching position;

FIG. 4 shows the vehicle electrical system according to FIG. 3 in a second switching position; FIG.

5 shows a schematic representation of a third embodiment of a vehicle electrical system for the internal combustion engine according to FIG. 1 in a first switching position; and

6 shows a schematic representation of a fourth embodiment of a vehicle electrical system for the internal combustion engine according to FIG. 1 in a first switching position.

The engine shown greatly simplified in FIG. 1 comprises a

Internal combustion engine 10, which is shown here by way of example as an Otto reciprocating engine with three cylinders. Furthermore, the internal combustion engine comprises a fresh gas line, via which fresh gas is supplied to the internal combustion engine, and an exhaust line, via which the exhaust gas, which is obtained in the combustion of the fresh gas with fuel in the cylinders, is dissipated. The internal combustion engine additionally comprises an exhaust gas turbocharger with a turbine 12 integrated into the exhaust gas line and a compressor 14 integrated in the fresh gas train. The flow through the turbine 12 by means of the exhaust gas causes a rotation of one

Turbinenlaufrads, which is transmitted via a shaft 16 to a compressor impeller. About a throttling or closable bypass 18, a so-called wastegate, a part of the exhaust gas can be passed to the turbine 12 in a known manner during operation of the internal combustion engine at or near full load. A charge air cooler 20 arranged downstream of the compressor 14 of the exhaust gas turbocharger serves at least partially to reverse the heating of the fresh gas associated with the compression.

The internal combustion engine further comprises an electrically driven compressor 22, which is integrated in the present embodiment upstream of the compressor 14 of the exhaust gas turbocharger (and thus in series with this) in the fresh gas train, but can also be downstream or parallel thereto. The electrically driven compressor 22 is inventively integrated into a vehicle electrical system 24 of a motor vehicle, not shown in the following, for driving the internal combustion engine is provided. The electrical system is indicated in Fig. 1 only as an angular field. The electrically driven compressor 22 is likewise designed to be bypassable by means of a restrictable or closable bypass 24. Thereby, a pressure drop of the fresh gas due to a flow through the compressor of the electrically driven compressor 22 is avoided, if this, as the longest time in the operation of the internal combustion engine, is not in operation.

2 shows a first embodiment of such a vehicle electrical system 24. This includes a first subnetwork, which in parallel a main energy storage 26 (the vehicle battery), a generator 28 which is driven by the internal combustion engine 10 to those for the operation of the motor vehicle To provide required electrical energy, and by way of example a single vehicle electrical system consumers 30 (eg, the lighting system, a fuel pump, an ignition system, etc.). In general, vehicles have a variety of

On-board network consumers (see Fig. 5 and 6) on.

Furthermore, the electrical system 24 of FIG. 2 includes a second subnetwork, which is also in

Parallel connection a starter motor 32, which serves to start the internal combustion engine 10, an electric drive motor 34 of the electrically driven compressor 22 and an additional energy storage 36 has. The additional energy storage 36 is designed as a supercapacitor.

The two subnetworks are interconnected by means of a so-called Q-diode 38. The Q-diode 38 is designed such that a flow of current from the first subnet over the

Additional energy storage 36 is possible when the drive motor 34 of the electrically driven compressor 22 (and also the starter motor 32) is deactivated, i. E. is not in operation. As a result, the additional energy storage 36 can be charged by the generator 28 and possibly also the main energy storage 26. However, one is locked

Current flow when the drive motor 34 of the electrically driven compressor 22 (or the starter motor 32) is in operation. This ensures that the energy required for the operation of the electrically driven compressor 22 (and the starter motor 32) only the additional energy storage 36 is removed and no equalization currents flow out of the first subnet, which could lead to an unwanted drop in the electrical voltage in this subnet. For this purpose, the Q-diode 38 of a motor control of

Engine designed controllable, wherein the Q-diode 38 in the activated or activated state blocks a flow of current from the first subnet in the second subnet (a reverse directed current flow is possible). In the uncontrolled or

deactivated state, however, a current flow through the Q-diode 38 in both directions is possible. In addition, the Q-diode 38 is designed such that it limits the amount of current during the charging of the additional energy storage 36.

3 and 4 show a second embodiment of a vehicle electrical system 24, which can be used in an internal combustion engine according to the invention according to FIG. 1. This differs from the vehicle electrical system 24 shown in FIG. 2 on the one hand in the integration of the starter motor 32 in the first subnetwork. On the other hand, two additional energy storage 36 (also supercapacitors) are provided, of which one is always integrated into the first subnet and the other in the second subnet. By means of a switching device 40 in the form of a simple 2-way switch, the integration of the two additional energy storage 36 can be changed. In this embodiment of the on-board network, one of the additional energy storage 36 is practically always connected to the drive motor 34 of the electrically driven compressor 22 and, with the electrically driven compressor 22 activated, can provide the electrical energy required for its operation. At the same time, the other additional energy storage 36 is integrated into the first subnet, so that it can be charged, if it is not already fully charged. Figs. 3 and 4 show the

corresponding charging and operating currents in the two switching positions of

Switching device 40, wherein the charging current is shown in solid line and the operating current for the drive motor 34 of the electrically driven compressor 22 with a dashed line.

In the embodiment of the on-board network 24 according to FIGS. 3 and 4, a current limiter 42 is integrated into the first subnetwork, which serves to limit the charging current flowing in the first subnetwork via the additional energy store 36 integrated therein high voltage drop in the first subnet to avoid. Such a current limiter 42 is particularly useful when using (super) capacitors as additional energy storage 36, since they can be charged in a very short time, which would be associated with correspondingly high charging currents. Such a current limiter could of course also be used in the vehicle electrical system 24 according to FIG. 2 (or FIGS. 5 and 6) in the local first subnetwork. Furthermore, in the vehicle electrical system 24 according to FIGS. 3 and 4, the starter motor 32 could also be integrated into the second subnetwork.

5 shows a third embodiment of a vehicle electrical system 24, which at a

inventive internal combustion engine according to FIG. 1 can be used. This differs from the vehicle electrical system 24 illustrated in FIGS. 3 and 4, in particular in the use of a switching device 40 which comprises a DC / DC converter 46 and a simple switch 48. The DC / DC converter 46 has two outputs which are each connected to one of the two additional energy storage 36. The drive motor 34 of the electrically driven compressor 22 is always connected via the switch 48 with the charged auxiliary energy storage 36, while the other additional energy storage 36 can be charged via the DC / DC converter 48 at the same time. By switching the switch 48, the integration of the two additional energy storage 36 can be exchanged in the two subnets.

6 shows a fourth embodiment of a vehicle electrical system 24, which at a

inventive internal combustion engine according to FIG. 1 can be used. This differs from the vehicle electrical system 24 shown in FIG. 5, in particular in the use of a switching device 40 which comprises a semiconductor switch 50, for example a transistor, in particular a MOSFET, and two simple switches 48. The semiconductor switch 50 is via one of the switches 48 with one of the two

Additional energy storage 36 are connected. This additional energy storage 36 can thus be loaded. The drive motor 34 of the electrically driven compressor 22 is simultaneously over the other switch 48 with the other, charged

Additional energy storage 36 connected, whereby a drive of the electrically driven compressor 22 can be ensured. By switching both switches 48, the integration of the two additional energy storage 36 can be exchanged in the two subnets.

Reference numeral is internal combustion engine

turbine

compressor

wave

bypass

Intercooler

electrically driven compressor

Board network

Main energy store

generator

Onboard consumers

starter motor

drive motor

Additional energy storage

Q-diode

switching device

current limiter

bypass

DC / DC converter

switch

Semiconductor switches

Claims

Patent phrases

Internal combustion engine with an electrically driven compressor (22) which is supplied with electrical energy from an electrical system (24), characterized in that the electrical system (24) comprises a first subnetwork with a main energy store (26), a generator (28) and at least one Consumers (30) and a separate or separable from the first subnet second subnet with an additional energy storage (36) and an electric drive motor (34) for the compressor, wherein the

Additional energy storage (36) as needed can be integrated into the first subnet to charge this.

Internal combustion engine according to claim 1, characterized by a first

Additional energy storage (36) and a second additional energy storage (36), wherein a switching device (40), in a first switching position, the first

Additional energy storage (36) in the first subnet and the second additional energy storage (36) integrated into the second subnet and integrated in a second switching position the second additional energy storage (36) in the first subnet and the first additional energy storage (36) in the second subnet

Internal combustion engine according to claim 1 or 2, characterized in that the one or more additional energy storage (36) comprises one or more capacitors / -en.

Internal combustion engine according to one of the preceding claims, characterized

characterized in that the electrically driven compressor (22) is driven intermittently and wherein a maximum energy requirement is defined for a single use of the electrically driven compressor (22) and wherein the one or more

Additional energy storage (36) has a charge capacity corresponding to a multiple of the maximum energy requirement.

Internal combustion engine according to claim 2 or 3 and claim 4, characterized in that the additional energy storage (36) have at least one charge capacity corresponding to the maximum energy requirement.