DE102012016247A1 - Method for operating e.g. commercial vehicle, involves switching on air compressor to suck, compress and load charge air to air reservoir during overrun operation of engine or during braking operation of engine - Google Patents

Abstract

The method involves supplying fresh air to combustion chambers (6) of an internal combustion engine (2) by an intake tract (7). Pressurized air is provided to a pressurized air load (22) and a cylindrical air compressor (25) for loading a pressurized air reservoir (23) of a pressurized air system (3). A suction-side of the air reservoir is attached to the intake tract downstream of a compressor (10). The air compressor is switched on to suck, compress and load charge air to the air reservoir during overrun operation of the engine or during braking operation of the engine. An independent claim is also included for a vehicle.

Description

The present invention relates to a method of operating a vehicle having an internal combustion engine for driving the vehicle and a compressed air system for supplying a compressed air consumer of the vehicle with compressed air. The invention also relates to such a vehicle, in particular a road vehicle.

From the DE 196 37 571 A1 For example, a compressor device is known that has an internal combustion engine for driving an air compressor or air compressor that provides compressed air for an external compressed air consumer. It can be provided that the air compressor charges a compressed air reservoir to which then the respective compressed air consumers can be connected. The internal combustion engine used in this case is equipped with an exhaust gas turbocharger, so that a compressor of the exhaust gas turbocharger is integrated into an inlet tract for supplying combustion chambers of the internal combustion engine with fresh air, while a turbine of the exhaust gas turbocharger is integrated into an exhaust tract for discharging exhaust gas from the combustion chambers of the internal combustion engine. Furthermore, it is provided in the known compression device that a suction line of the air compressor is connected to the inlet tract downstream of the compressor. In this way, the air compressor charge air can be supplied in order to realize in this way favorable two-stage compressed air generation.

In the known compression device of the exhaust gas turbocharger is specifically designed so that it generates an excessive boost pressure in the stationary nominal operating point of the internal combustion engine, ie a boost pressure whose pressure level is well above a required for optimal operation of the engine pressure levels. As a result, a charge air excess is generated, which can be permanently supplied to the air compressor inlet side during operation of the internal combustion engine.

Such a compression device is used, for example, on construction sites to supply compressed air tools, such as pneumatic hammers or pneumatic tools, with compressed air. In such a compression device, the internal combustion engine is used essentially exclusively for driving the air compressor.

In vehicles compressed air systems can be used for different purposes. For example, larger road vehicles, such as commercial vehicles, may be equipped with air brake systems and air suspension devices. To supply such a compressed air system with the required compressed air, an air compressor can be used, which is drive-connected in a suitable manner with the internal combustion engine, for example via a gear drive. The air compressor usually sucks in the air to be compressed from the environment. Depending on the pressure level, the air compressor must be designed for high performance. Powerful air compressors require appropriate installation space and corresponding drive power. Furthermore, the size is accompanied by a correspondingly high weight. In addition, the air compressor on the inlet side an air filter upstream in order to avoid contamination of the air compressor or the compressed air system.

The present invention is concerned with the problem of providing for a vehicle of the type mentioned above or for an associated operating method, an improved embodiment, which is characterized in particular by the fact that the vehicle has an improved energy efficiency. In particular, the air compressor is to build comparatively small or compact.

This problem is solved according to the invention by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of connecting the air compressor on the suction side to the intake tract in a vehicle application, specifically downstream of the compressor. In this way, the air compressor sucks the air to be compressed no longer directly from the environment, but from the intake tract of the internal combustion engine, in a place where the fresh air is already charged with the help of the compressor and on which the fresh air usually already with Help of an air filter of the intake tract has been filtered. Thus, a two-stage compression of the compressed air is realized, namely a first compression stage using the compressor of the intake tract and a second compression stage using the air compressor. As a result, the air compressor can be made significantly smaller, since it only has to produce a reduced differential pressure compared to an air compressor, which sucks the air to be compressed directly from the environment. For example, instead of a two-cylinder air compressor, a one-cylinder air compressor can be used, so that weight, space and required to drive the air compressor driving power can be reduced, whereby increased efficiency is achievable.

In addition, the invention proposes to turn on the air compressor during a coasting operation of the internal combustion engine or during a braking operation of the internal combustion engine. This charge air sucks only when the air compressor is switched on the inlet tract, compresses them and can supply them to a compressed air reservoir of the compressed air system. This special control of the air compressor is based on the consideration that during the overrun of the internal combustion engine and during the braking operation of the internal combustion engine, a comparatively high boost pressure is present or can be generated to cause an intensive precompression for the air compressor, without causing the fresh air supply of the Internal combustion engine is impaired. Such a pushing operation is characterized in that when the gear is engaged, the fuel supply of the internal combustion engine is interrupted and the internal combustion engine is entrained by the rolling vehicle. A braking operation is characterized in that in addition to the interruption of the fuel supply further measures are performed to dissipate resulting from the internal combustion engine during the compression of the combustion air in the combustion chamber. For example, it is known to use a brake flap or stowage flap in the outlet tract in order to increase the exhaust backpressure. Such a braking operation is also referred to as a "dust brake". Alternatively, a so-called "decompression brake" may be used, in which combustion air compressed or compressed by the piston is discharged from the combustion chambers, whereby a decompression can take place in the respective cylinder. Usually, the decompression brake and the dust brake are combined. Furthermore, a mixed operation is possible in which at least one cylinder is operated in the overrun mode, while at least one further cylinder is operated in the braking mode. Due to the different variants of thrust and / or braking operation, the respectively required braking power can be set variably.

According to an advantageous embodiment, it is provided that the air compressor is switched on only during the thrust or braking operation of the internal combustion engine. This ensures that the air compressor can suck at any time during a drive operation of the internal combustion engine air from the intake tract. Thus, adverse effects on the operation of the internal combustion engine can be avoided.

According to another advantageous embodiment, it can be provided that the exhaust-gas turbocharger is driven to generate a high boost pressure during the thrust or braking operation. In the mode of operation of the vehicle according to the invention, the highest possible boost pressure is generated in these operating states, which can then be used to supply the air compressor.

A boost pressure boost can be realized with the aid of the exhaust gas turbocharger, for example, by closing a wastegate valve. Additionally or alternatively, in an exhaust gas turbocharger whose turbine is equipped with a variable turbine geometry, the variable turbine geometry can be specifically controlled so that there is an increased speed for a turbine of the turbine, which by coupling the turbine wheel via a common shaft with a compressor the compressor leads to a correspondingly increased speed and capacity at the compressor wheel. An increased delivery rate at the compressor wheel is accompanied by an increased boost pressure.

In another advantageous embodiment, the air compressor can be connected to the inlet tract downstream of a charge air cooler on the inlet side or on the suction side. This ensures that the air compressor can only suck in cooled charge air, which improves the durability of the air compressor.

The vehicle according to the invention is characterized by a control device which is provided for operating the compressed air system and which is coupled for this purpose at least with the air compressor. Furthermore, this control device is coupled to a motor control device for operating the internal combustion engine, whereby the control device knows the current operating state of the internal combustion engine. Furthermore, the control device is designed or programmed so that it can carry out the operating method explained above.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawing and from the associated description of the figures with reference to the drawing.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description.

The only 1 shows a schematic diagram of a basic representation of a vehicle in the field of an internal combustion engine.

Corresponding 1 includes a vehicle shown here only partially 1 , which is preferably a road vehicle, an internal combustion engine 2 and a compressed air system 3 , Instead of a road vehicle, such as a commercial vehicle, it may be the vehicle 1 also one another vehicle 1 act, such as an off-road vehicle.

The internal combustion engine 2 includes a crankcase 4 in several cylinders 5 each a combustion chamber 6 contains. Furthermore, the internal combustion engine comprises 2 an inlet tract 7 for supplying fresh air to the combustion chambers 6 , an exhaust tract 8th for removing exhaust gas from the combustion chambers 6 and an exhaust gas turbocharger 9 , The turbocharger 9 has in the usual way a compressor 10 and a turbine 11 on, which are drivingly connected to each other. In detail, the compressor contains 10 a compressor wheel 12 that has a drive shaft 13 with a turbine wheel 14 is drive connected. The compressor 10 is in the inlet tract 7 bound to those from an environment 15 sucked fresh air to charge air to compress. The turbine 11 is on the other hand in the exhaust tract 8th arranged.

The inlet tract 7 includes an air filter 16 , upstream of the compressor 10 is arranged, and a charge air cooler 17 , the downstream of the compressor 10 is arranged. Further, the inlet tract 7 with a charge air housing 18 equipped, which the charge air on the individual cylinders 5 or combustion chambers 6 distributed.

The exhaust tract 8th includes an exhaust manifold 19 that's the exhaust from the combustion chambers 6 absorbs and brings together. Downstream of the exhaust manifold 19 then is the turbine 11 arranged. On the turbine 11 may be followed by exhaust aftertreatment devices, such as catalysts, particulate filters, and mufflers.

To operate the internal combustion engine 2 is expedient a motor control device 20 provided in an appropriate manner with the internal combustion engine 2 is coupled. Indicated in 1 a coupling line 21 which the engine control device 20 purely exemplary with the engine block 4 or with the internal combustion engine 2 combines.

The compressed air system 3 serves to supply a compressed air consumer indicated here by a frame drawn with a broken line 22 with compressed air. In the compressed air consumer 22 it may be, for example, a pneumatic brake system of the vehicle 1 act. The compressed air system 3 also includes a compressed air reservoir 23 for providing the compressed air for the compressed air consumer 22 , In the example, the compressed air reservoir comprises 23 two storage tanks 24 , Furthermore, the compressed air system 3 with an air compressor or air compressor 25 equipped with the help of compressed air storage 23 can be charged. For this purpose is a pressure line 26 provided that a pressure-side connection 27 the air compressor 25 with the air pressure accumulator 23 fluidly connects. Furthermore, there is a suction-side connection 28 the air compressor 25 via a suction line 29 with the inlet tract 7 fluidly connected. There is a connection point 30 over which the suction line 29 to the inlet tract 7 is connected, downstream of the intercooler 17 and thus downstream of the compressor 10 arranged. Furthermore, said connection point 30 upstream of the charge air housing 18 positioned. To drive the air compressor 25 can be a suitable, switchable drive connection to the internal combustion engine 2 or a separate switchable drive may be provided.

The compressed air system 3 has a control device 31 on that with the engine control unit 20 via a corresponding connection line 32 is coupled and the via a corresponding control line 33 with the air compressor 25 connected is. Furthermore, the control device 31 via a corresponding connection line 34 with the compressed air consumer 22 be coupled.

In the embodiment shown here, the turbine 11 the exhaust gas turbocharger 9 with a waste gate valve 35 equipped with a bypass to bypass the turbine wheel 14 controls. In addition, the turbine can 11 with a variable turbine geometry 36 be equipped with their help, the flow of the turbine wheel 14 can be changed in terms of flow angle and flow cross-section. The waste gate valve 35 and the variable turbine geometry 36 here are only rudimentary symbolized as rectangles. These components are well known and need no further explanation.

The vehicle presented here 1 can preferably be operated as follows:
During normal operation or drive operation of the internal combustion engine 2 drives the internal combustion engine 2 the vehicle 1 Accordingly, and generates the drive power for propulsion of the vehicle 1 , During this drive operation of the internal combustion engine 2 provides the controller 31 for being the air compressor 25 is off. The supply of the compressed air consumer 22 with compressed air takes place in this case via the pressure accumulator 23 ,

Is the internal combustion engine 2 in contrast, in a coasting operation or in a braking operation, in which at least one cylinder 5 in overrun mode or at least one cylinder 5 be operated in braking mode, the controller switches 31 the air compressor 25 at. The air compressor 25 then sucks charge air from the intake tract 7 on, compresses them and leads them to the compressed air storage 23 to.

The control device 31 may during this coasting or braking operation, for example via the engine control device 20 , Furthermore Make sure the exhaust gas turbocharger 9 generates a sufficiently high boost pressure. For example, this can be the waste gate valve 35 and / or the variable turbine geometry 36 be controlled accordingly.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19637571 A1 [0002]

Claims (4)

Method for operating a vehicle ( 1 ), which is an internal combustion engine ( 2 ) for driving the vehicle ( 1 ) and a compressed air system ( 3 ) for supplying a compressed air consumer ( 22 ) of the vehicle ( 1 ) with compressed air, - wherein the internal combustion engine ( 2 ) an inlet tract ( 7 ) for supplying combustion chambers ( 6 ) of the internal combustion engine ( 2 ) with fresh air, an outlet tract ( 8th ) for discharging exhaust gas from the combustion chambers ( 6 ) and an exhaust gas turbocharger ( 9 ), whose compressor ( 10 ) in the inlet tract ( 7 ) and whose turbine ( 11 ) the compressor ( 10 ) and in the exhaust tract ( 8th ), the compressed air system ( 3 ) a compressed air reservoir ( 23 ) for providing the compressed air for the respective compressed air consumer ( 22 ) and an air compressor ( 25 ) for charging the compressed air reservoir ( 23 ), the suction side of the inlet tract ( 7 ) downstream of the compressor ( 10 ) is connected, - in which during a coasting operation of the internal combustion engine ( 2 ) or during a braking operation of the internal combustion engine ( 2 ) the air compressor ( 25 ) is switched on, in order to suck in charge air, to compress and the compressed air storage ( 23 ). Method according to claim 1, characterized in that the air compressor ( 25 ) is switched on only during overrun or braking operation. A method according to claim 1 or 2, characterized in that during the overrun operation or the braking operation of the exhaust gas turbocharger ( 9 ) is driven to increase the boost pressure. Vehicle, in particular road vehicle, - with an internal combustion engine ( 2 ) for driving the vehicle ( 1 ) comprising a motor control device ( 20 ) for operating the internal combustion engine ( 2 ), an inlet tract ( 7 ) for supplying combustion chambers ( 6 ) of the internal combustion engine ( 2 ) with fresh air, an outlet tract ( 8th ) for discharging exhaust gas from the combustion chambers ( 6 ) and an exhaust gas turbocharger ( 9 ), whose compressor ( 10 ) in the inlet tract ( 7 ) and whose turbine ( 11 ) in the outlet tract ( 8th ) and the compressor ( 10 ), - with a compressed air system ( 3 ) for supplying a compressed air consumer ( 22 ) of the vehicle ( 1 ) with compressed air, the compressed air reservoir ( 23 ) for providing the compressed air for the respective compressed air consumer ( 22 ), an air compressor ( 25 ) for charging the compressed air reservoir ( 23 ), the suction side of the inlet tract ( 7 ) downstream of the compressor ( 10 ), and a control device ( 31 ) for operating the compressed air system ( 3 ) connected to the engine control device ( 20 ) and with the air compressor ( 25 ) and which is designed and / or programmed for performing the method according to one of claims 1 to 3.

Images