Method of operating a motor vehicle and motor vehicle

Abstract

A method of operating a motor vehicle having an internal combustion engine, wherein the internal combustion engine has at least one combustion engine which is connected by a rotary drive via a transmission and optionally a clutch with powered wheels of the motor vehicle, and further comprises a fresh gas line, and wherein in the fresh gas line, a compressor is integrated, which is associated with a trim controller, by means of which an edge-side portion of the inlet cross section of a compressor impeller of the compressor is coverable to a variable extent. In this case, in a release position of the trim controller, the edge-side portion of the inlet cross section is covered relatively little, preferably the least possible, and in a covering position of the trim controller, is mostly covered, preferably as much as possible.

Claims

1. A method for operating a motor vehicle having an internal combustion engine system, the method comprising: operating an engine that is connectable by a rotary drive to wheels of the motor vehicle via a transmission; compressing fresh gas via a compressor being integrated in a fresh gas line, wherein the compressor is associated with a trim controller, and via the trim controller, an edge-side portion of an inlet cross section of a compressor impeller of the compressor is covered to a variable extent; and wherein in a release position of the trim controller, the edge-side portion of the inlet cross section is covered to a lesser extent than when the trim controller is in a covering position; and adjusting the trim controller from the release position to the covering position, via an engine control unit, when the engine transitions from a first operating state in which the transmission is in a first gear ratio shift position to a second operating state in which the transmission is in a second gear ratio shift position.

2. The method according to claim 1, wherein said adjusting the trim controller from the release position to the covering position further includes: uncovering the edge-side portion of the inlet cross section in the release position; and uncovering the edge-side portion of the inlet cross in the covering position.

3. The method according to claim 1, further comprising at least one of: adjusting the trim controller from the covering position to the release position when the engine is operated in the second operating state with a load beyond a defined limit; and maintaining the trim controller in the covering position when the engine is operated in the second operating state with at most one load corresponding to the defined limit.

4. The method according to claim 3, further comprising resetting the trim controller to the release position when a value of a mass flow of the fresh gas through the compressor corresponds to a value immediately prior to the transition and/or the value of the mass flow is at a defined distance from a surge line of the compressor.

5. A motor vehicle comprising: an internal combustion engine system including: an engine, which is connected by a rotary drive via a transmission with wheels of the motor vehicle; a fresh gas line; a compressor integrated in the fresh gas line; a trim controller associated with the compressor, wherein via the trim controller, an edge-side portion of an inlet cross section of a compressor impeller of the compressor is covered to a varying extent; and wherein in a release position of the trim controller, the edge-side portion of the inlet cross section is covered to a lesser extent than when the trim controller in a covering position; and a control device configured for an automated execution of: operating the engine that is connected by the rotary drive via the transmission with the wheels of the motor vehicle; compressing fresh gas via the compressor integrated in the fresh gas line; and adjusting the trim controller from the release position to the covering position when the engine transitions from a first operating state in which the transmission is in a first gear ratio shift position to a second operating state in which the transmission is in a second gear ratio shift position.

6. The motor vehicle according to claim 5, wherein the trim controller comprises an annular diaphragm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 illustrates a motor vehicle according to the invention;

(3) FIG. 2 illustrates an internal combustion engine for a motor vehicle according to the invention;

(4) FIG. 3 illustrates a longitudinal section through a compressor for an internal combustion engine according to the invention with an associated trim controller in a position covering the inlet cross section of a compressor impeller as little as possible;

(5) FIG. 4 illustrates the compressor according to FIG. 3 with the trim controller in a position covering the inlet cross section of the compressor impeller as much as possible;

(6) FIG. 5 illustrates in a total of four diagrams, the waveforms of various parameters during a first exemplary shifting operation during operation of a motor vehicle according to the invention; and

(7) FIG. 6 illustrates in a total of four diagrams, the waveforms of various parameters during a second exemplary shifting operation during operation of a motor vehicle according to the invention.

DETAILED DESCRIPTION

(8) FIG. 1 shows a simplified representation of an inventive motor vehicle with an internal combustion engine system 66 comprising an engine 10, which is connected or connectable via a rotary drive with wheels 72 of the motor vehicle via a clutch 68 and a transmission 70. The internal combustion engine system 66 may be designed, for example, according to the one shown in FIG. 2.

(9) The engine 10 of the internal combustion engine system 66 according to FIG. 2 formed of a plurality of cylinders 12. The cylinders 12, together with pistons guided up and down therein and a cylinder head, define combustion chambers in which fresh gas is combusted together with fuel. The fuel, controlled by a control device 14 (engine control), is injected directly into the combustion chambers by means of injectors 16. The combustion of the fuel fresh gas mixture amounts leads to cyclic up and down movements of the pistons, which in turn are transferred in a known manner via connecting rods to a crankshaft, whereby the crankshaft is driven in rotation.

(10) The fresh gas is supplied to the engine 10 via a fresh gas line and is aspirated from the environment via an intake port 18, cleaned in an air filter 20 and then fed into a compressor 22, which is part of an exhaust gas turbocharger. The fresh gas is compressed by means of the compressor 22, then cooled in a charge-air cooler 24 and finally fed to the combustion chambers. The compressor 22 is driven by means of an exhaust gas turbine 26 of the exhaust gas turbocharger, which is integrated into an exhaust line of the internal combustion engine system 66. Exhaust gas formed by the fuel fresh gas mixture amounts in the combustion chambers of the engine 10 is discharged through the exhaust line from the engine 10 and thereby flows through the exhaust gas turbine 26. This leads in a known manner to a rotating drive of a turbine impeller, which is non-rotatably connected via a shaft 28 to a compressor impeller 30 (see FIGS. 3 and 4) of the compressor 22. The rotating drive of the turbine impeller is thus transferred to the compressor impeller 30.

(11) In order to optimally implement the enthalpy of the exhaust gas for producing compression performance by means of the exhaust gas turbocharger during operation of the engine 10 at varying loads and speeds, the exhaust gas turbine 26 of the exhaust gas turbocharger may optionally comprise a device for variable turbine geometry (VTG) 32, which is controllable by means of the control device 14. This may comprise in a known manner a plurality of guide blades, which are arranged in an inlet channel of the exhaust gas turbine 26 and which are individually rotatable, wherein these may be adjusted together by means of an adjusting device. As a function of the rotational positions of the guide blades, these more or less narrow the free flow cross section in the inlet channel of the exhaust gas turbine 26 and also influence the portion of the primary flow of the turbine impeller and the orientation of this flow.

(12) A throttle valve 34, likewise controllable by means of the control device 14, is integrated downstream of the compressor 22 in the charge-air duct, i.e. in the portion of the fresh gas line which is located between the compressor 22 and the engine 10.

(13) The internal combustion engine system 66 may comprise an exhaust gas recirculation line 36 to recirculate (low pressure) exhaust gas, in which the exhaust gas is branched off from a portion of the exhaust gas line, which is located downstream of the exhaust gas turbine 26 and, in particular, also downstream of an exhaust gas aftertreatment device 38, such as a particulate filter, and is introduced into a section of the fresh gas line upstream of the compressor impeller 30. The amount of exhaust gas recirculated via the exhaust gas recirculation line 36 can in this case be controlled or regulated by means of a control valve 40 which is controllable by means of the control device 14. Further, an exhaust gas cooler 42 may be integrated in the exhaust gas recirculation line 36 for cooling the exhaust gas recirculated through it.

(14) The compressor 22 is associated with a trim controller 44 by means of which the incident flow of the compressor impeller 30 can be influenced by the fresh gas. For this purpose, the trim controller 44 or an associated actuator can be controlled by means of the control device 14. The exhaust gas recirculation line 36 may end in the fresh gas line upstream or on the side of the trim controller 44 facing away from the compressor impeller 30. An orifice downstream or in the region of the trim controller 44 (and upstream of the compressor impeller 30) is also possible.

(15) In a longitudinal section, FIGS. 3 and 4 each show a possible embodiment for such a compressor 22. This compressor 22 may be provided, for example, for an internal combustion engine system 66 according to FIG. 2, wherein the trim controller 44 and a connection channel 46 for the exhaust gas recirculation line 36 are integral parts of the compressor 22. This is indicated in FIG. 2 by a dashed border.

(16) The compressor 22 according to FIGS. 3 and 4 includes a housing 50, which may constitute a partial housing of an overall housing of an exhaust gas turbocharger. The housing 50 of the compressor 22 forms a flow space 52 within which the compressor impeller 30 is rotatably mounted. On the inlet side, the flow space 52 has an inlet cross section located in an inlet plane 54. Via an inlet channel 56 likewise formed by the housing 50 of the compressor 22, fresh gas can be guided from a compressor inlet 58 to the compressor impeller 30. On the outlet side, the flow space 52 is limited by an “outlet plane” surrounding outlet edges of impeller blades 60 of the compressor impeller 30. There, it is adjoined by a diffuser space 62 also surrounding the outlet edges of the impeller blades 60, and adjoining that, which is not shown in FIGS. 3 and 4, is a compressor volute. A compressor outlet branches off from the compressor volute.

(17) Within the inlet channel 56, the trim controller 44 is arranged as closely as possible to the inlet cross section of the compressor impeller 30. The trim controller 44 includes an annular diaphragm 48 with a structure basically known from photo lenses. In a covering position according to FIG. 4, in a peripherally located annular area of the inlet cross section, the trim controller 44 mostly prevents an inflow of fresh gas flowing in the direction of the compressor impeller 30 to the compressor impeller 30. In this way, the trim controller 44 focuses this fresh gas flow on a hub-proximal portion of the compressor impeller 30. In a release position according to FIG. 3, however, the fresh gas can flow into the compressor impeller 30 over the entire inlet cross section. The diaphragm elements forming the 14s annular diaphragm 48, which are each pivotably mounted about an axis within the housing 50 for opening or closing the annular diaphragm 48, in the release position are arranged completely in an annular recess 64 of the housing 50.

(18) According to the invention, it is provided that for a transition from a first operating state of the internal combustion engine system 66, in which the transmission 70 is in a first gear ratio shift position i.sub.1 and the trim controller 44 is in the release position, to a second operating state of the internal combustion engine system 66, in which the transmission 70 is in a second gear ratio shift position i.sub.2, the trim controller 44 is moved to the covering position. This is intended to prevent rattling due to recirculation of compressed fresh gas from the high pressure side of the compressor to the low pressure side, which would undulatingly propagate into the portion of the fresh gas line located upstream of the compressor impeller. FIGS. 5 and 6 clarify this approach based on four graphs, which show by way of example concurrent waveforms of different characteristics during a portion of the operation of the internal combustion engine system 66 involving a shifting operation.

(19) In each case, the top diagram of FIGS. 5 and 6 shows the gear ratio i and thus the respectively applied gear ratio shift position i.sub.1, i.sub.2 of the transmission 70. The diagram right below and consequently, the upper of the two middle diagrams, shows the course of the boost pressure p.sub.2 in the charge-air duct of the fresh gas line and thus downstream of the compressor 22, while the lower of the two middle diagrams represents the mass flow {dot over (m)} of the fresh gas guided through the compressor 22. Finally, each of the bottom diagrams of FIGS. 5 and 6 shows the opening degree S.sub.T of the trim controller 44, wherein the opening degree S.sub.T1 corresponds to the release position in which the inlet cross section of the compressor impeller 30 is released as much as possible, and the opening degree S.sub.T2 corresponds to the covering position in which said inlet cross section is released as little as possible.

(20) The diagrams of FIG. 5 show an operation of the internal combustion engine system 66 during an acceleration process of a motor vehicle powered by the internal combustion engine system 66, in which initially in a relatively high gear ratio shift position i.sub.1, for example during operation of the engine 10 under full load, acceleration takes place, and in the meantime, for achieving a higher drive power, a shift is made to a smaller gear ratio shift position i.sub.2. This shifting operation leads to a temporary drop in the mass flow {dot over (m)} generally increasing during the given portion of the acceleration process while at the same time substantially steadily increasing the boost pressure p.sub.2. This decrease in the mass flow m is due to the temporary reduction of the driving power for the compressor 22 through the exhaust gas turbine, which is caused by the load that is temporarily interrupted or reduced for the shifting operation during operation of the engine 10. During the shifting operation, there is thus a temporary, relatively high boost pressure p.sub.2 and therefore a relatively high compressor pressure ratio over the compressor 22 with a simultaneously relatively low mass flow, resulting in a relevant recirculation of compressed fresh gas from the high pressure side to the low pressure side of the compressor 22, which can thus lead to the rattling noise. In order to avoid or to minimize such rattling, the trim controller 44, which in the part of the acceleration operation prior to the shifting operation has been moved from the covering position S.sub.T2 to the release position S.sub.T1 to ensure the operation of the compressor 22 that is optimal for the boost pressure, is temporarily moved back into the covering position S.sub.T2. Thereby, the trim controller 44 blocks or minimizes the propagation of the recirculation of fresh gas, which takes place on the edge of the inlet cross section of the compressor impeller 30 and thus in the area covered by the trim controller 44 in the covering position S.sub.T2, into the portion of the fresh gas line situated upstream of the trim controller 44, such that vibrational excitations which can lead to the rattling noise can be avoided or at least minimized. Since after the shifting operation, the acceleration operation is continued in the smaller gear ratio shift position i.sub.2, the trim controller 44 is moved back to the release position to ensure an operation of the compressor 22 optimal for increasing the boost pressure.

(21) The diagrams of FIG. 6 show an operation of the internal combustion engine system 66 during acceleration, for example, an operation of the engine 10 at full load at a relatively small gear ratio shift position i.sub.1, which transitions into a shifting operation with a larger gear ratio shift position i.sub.2. Subsequently, the internal combustion engine system 66 is operated substantially stationary in the plane for, for example, a constant travel of the motor vehicle driven by said engine. It can be seen that during the shifting operation, the mass flow {dot over (m)} drops significantly faster than the boost pressure p.sub.2, so again there are conditions that favor a rattling noise. In order to avoid or minimize such a rattling noise, the trim controller 44, which during acceleration was set to the release position S.sub.T1, is set to the covering position S.sub.T2 for the shifting operation or during the shifting operation. Since no further acceleration of the motor vehicle is planned after shifting, in this exemplary embodiment the mass flow {dot over (m)} of the fresh gas flowing through the compressor is so low that with the simultaneously applied compressor pressure ratio, the operation of the compressor 22 with the trim controller 44 in the covering position S.sub.T2 is more advantageous for the compressor efficiency, so that after the shifting operation, a return to the release position S.sub.T1 it is not necessary. If after the shifting operation, further acceleration of the motor vehicle were planned, the trim collector 44 could again be moved to the covering position S.sub.T2, as provided in the embodiment of FIG. 5.

(22) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.