Driving device for driving a vehicle as well as method and computer program product for operating this driving device

Abstract

A driving device for driving a vehicle includes an internal combustion engine, a feed line for feeding combustion air to the internal combustion engine, a discharge line for discharging exhaust gases from the internal combustion engine, a charge air cooler that is arranged in the feed line for cooling the combustion air, and a recirculation line branching off the discharge line for recirculating the exhaust gas from the discharge line into the feed line. The recirculation line includes a bypass line that the exhaust gas can be fed to the internal combustion engine through the charge air cooler and/or bypassing the charge air cooler.

Claims

1. A driving device for driving a vehicle, comprising: an internal combustion engine; a feed line configured to feed combustion air to the internal combustion engine; a discharge line configured to discharge exhaust gases from the internal combustion engine; a charge air cooler in fluid communication with the feed line and configured to cool the combustion air; a recirculation line branching off the discharge line and configured to recirculate exhaust gas from the discharge line into the feed line, wherein exhaust gases can be fed by the recirculation line to the internal combustion engine through the charge air cooler; a bypass line configured to feed exhaust gas to the internal combustion engine bypassing the charge air cooler, wherein the bypass line is in communication with the recirculation line; a shut-off and directional control device configured to interact with the recirculation line and the bypass line; a control unit configured to actuate the shut-off and directional control device such that flow of the recirculated exhaust gas line is: (i) selectively shut off, or (ii) directed through the charge air cooler to the internal combustion engine, or (iii) directed to the internal combustion engine bypassing the charge air cooler; and a status sensor configured to determine a pressure in the feed line and the discharge line of the driving device, wherein the control unit is configured to shut off the recirculation line when the pressure in the feed line is greater than the pressure in the discharge line.

2. The driving device according to claim 1, wherein the shut-off and directional control device comprises an actuating device settable in at least two positions including a first position to direct the recirculated exhaust gas through the charge air cooler to the internal combustion engine and a second position to direct recirculated exhaust gas to the internal combustion engine bypassing the charge air cooler.

3. The driving device according to claim 1, wherein the status sensor device comprises at least one of a pressure sensor arranged in the feed line for measuring pressure in the feed line, or a pressure sensor configured to measure at least one of a pressure in feed line or a pressure in the discharge line, or a mass flow measuring unit configured to measure the mass flow of at least one of the combustion air in the feed line or the exhaust gas in the discharge line, or a tachometer measuring a rotational speed of the internal combustion engine.

4. The driving device according to claim 1, further comprising a flow rate regulating device configured to interact with the recirculation line for adjusting the flow rate of the recirculated exhaust gas.

5. The driving device according to claim 1, further comprising a recirculation cooler that is arranged in the recirculation line for cooling the recirculated exhaust gas.

6. The driving device according to claim 1, further comprising a turbocharger with a turbo compressor in fluid communication with the feed line for compressing the combustion air and an exhaust gas turbine in fluid communication with the discharge line for driving the turbocharger.

7. The driving device according to claim 6, wherein the recirculation line at a first inlet branches into the feed line and the charge air cooler, wherein the turbo compressor seen in flow direction of the combustion air to the internal combustion engine is arranged upstream of the first inlet, wherein the recirculation line branches off the discharge line at a branch-off point, and wherein the exhaust gas turbine is arranged downstream of the branch-off point in flow direction of the exhaust gas away from the internal combustion engine.

8. The driving device according to claim 1, further comprising a throttle valve arranged in the feed line between the charge air cooler and the internal combustion engine, and wherein the bypass line leads into the feed line at a second inlet arranged either between the charge air cooler and the throttle valve or between the throttle valve and the internal combustion engine.

9. A vehicle with a driving device according to claim 1.

10. A method for operating a driving device for driving a vehicle, comprising: determining a current operational status of the driving device and generating corresponding status signals with a status sensor device; communicating the status signals to a control unit; determining at least one of a first pressure in a feed line seen in flow direction of combustion air to an internal combustion engine upstream of a charge air cooler or a second pressure in the feed line downstream of the charge air cooler with the control unit based on the status signals; determining an exhaust gas pressure in a discharge line with the control unit based on the status signals; comparing the at least one of the first or second pressures with the exhaust gas pressure; and actuating a shut-off and directional control device using the control unit such that the shut-off and directional control device selectively shuts off the recirculation line when the at least one of the first or second pressures is greater than the exhaust gas pressure.

11. The method for operating a driving device according to claim 10 further comprising: determining the current operational status of the driving device and generating corresponding status signals with the status sensor device; communicating the status signals to the control unit; determining the first pressure in the feed line seen in flow direction of the combustion air to the internal combustion engine upstream of the charge air cooler and a second pressure in the feed line downstream of the charge air cooler based on the status signals; determining the exhaust gas pressure in the discharge line with the control unit based on the status signals; comparing the first pressure and the second pressure with the exhaust gas pressure; actuating the shut-off and directional control device with the control unit such that the shut-off and directional control device: (i) shuts off the recirculation line when the first pressure and the second pressure are greater than the exhaust gas pressure; (ii) recirculates exhaust gas to the internal combustion engine bypassing the charge air cooler when the exhaust gas pressure is greater than the second pressure; or (iii) recirculates exhaust gas through the charge air cooler to the internal combustion engine when the exhaust gas pressure is greater than the first pressure.

12. The method according to claim 10, wherein the current operational status of the driving device is determined by measuring the mass flow of at least one of the combustion air flowing through the feed line or the exhaust gas flowing through the discharge line with a mass flow measuring unit.

13. The method according to claim 10, wherein the current operational status of the driving device is determined by measuring a rotational speed of the internal combustion engine with a tachometer.

14. The method according to claim 10, wherein the current operational status of the driving device is determined by measuring at least the first or second pressure with a pressure sensor suitably arranged in the feed line.

15. A computer program product for operating a driving device with a program code that is stored on a non-transitory computer readable medium for carrying out the method according to claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements.

(2) FIG. 1 is a diagram of an exemplary embodiment of a driving device according to the present disclosure;

(3) FIG. 2 is a graphic representation of the differential pressure p.sub.2 as a function of the rotational speed of the internal combustion engine and the effective mean pressure;

(4) FIG. 3 is a graphic representation of the differential pressure p.sub.1 as a function of the rotational speed of the internal combustion engine and of the effective mean pressure; and

(5) FIG. 4 is a flow diagram of the steps of the method according to the present disclosure and of the computer program according to the present disclosure.

DETAILED DESCRIPTION

(6) The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background of the invention or the following detailed description.

(7) In FIG. 1, a driving device 10 according to the present disclosure for driving a vehicle which is not shown is shown by way of a diagram. The driving device 10 according to the present disclosure includes an internal combustion engine 12, for example a four-cylinder spark-ignition or diesel engine, which provides the power needed for driving the vehicle. The internal combustion engine 12 usually operates according to the four-stroke principle, while a two-stroke principal is also conceivable. The driving device 10 includes a feed line 16, with which the internal combustion engine 12 can be supplied with combustion air. In the feed line 16, a throttle valve 18 is arranged, with which the load of the internal combustion engine 12 can be changed. The exhaust gases which are created during the combustion of the mixture of combustion air and fuel are discharged from the internal combustion engine 12 by way of a discharge line 20.

(8) For aspirating the combustion air from the surroundings, the internal combustion engine 12 can include an aspiration device 22, which for example can include an air filter. The discharge line 20 includes an exhaust gas treatment system 24, which can include catalytic converters which are not shown in more detail, in order to convert toxic components contained in the exhaust gas into non-toxic compounds.

(9) The driving device 10 includes a turbocharger 26, which includes a turbo compressor 30 arranged in the feed line 16 and an exhaust gas turbine 32 arranged in the discharge line 20, which are connected to one another by means of a shaft 34. Between the turbo compressor 30 and the throttle valve 18 a charge air cooler is arranged, with which the compressed combustion air can be cooled.

(10) At a branch off point 37 between the internal combustion engine 12 and the exhaust gas turbine 32, a recirculation line 38 branches off the discharge line 20, with which exhaust gas from the discharge line 20 can be introduced back into the feed line 16. In the recirculation line 38, a recirculation cooler 40 is arranged with which the recirculated exhaust gases can be cooled. Downstream of the recirculation cooler 40 a regulating valve 42 is arranged with which the flow rate of the recirculated exhaust gas can be changed. The recirculation line 38 leads into the feed line 16 at a first inlet 46, wherein the inlet 46 is arranged between the turbo compressor 30 and the charge air cooler 36. The case in which the first inlet 46 is directly arranged on the charge air cooler 36 and in particular at the upstream inlet of the charge air cooler is not shown.

(11) Downstream of the regulating valve 42, a shut-off and directional control device 44 is arranged in which a bypass line 45 branches off the recirculation line 38. In the shown example, the shut-off and directional control device is embodied as a three-way valve 47. Furthermore, the bypass line 45 includes a second inlet 48 which is arranged between the throttle valve 18 and the internal combustion engine 12, so that the bypass line 45 leads into the feed line 16 downstream of the charge air cooler 36.

(12) In addition, the driving device 10 includes a status sensor device 49, which in the shown example includes a pressure sensor 50 which is arranged directly in front of the internal combustion engine 12, for example in front of inlet valves of an inlet manifold which is not shown here for determining a second pressure p.sub.z2 of the combustion air or the mixture of combustion air and recirculated exhaust gas between the charge air cooler 36 and the internal combustion engine 12. The pressure sensor 50 generates pressure signals corresponding to the determined second pressure p.sub.z2 and conducts these on to a control unit 54 via electrical lines 52.

(13) In addition to this, the status sensor device 49 includes a mass flow measuring unit 56 with which the mass flow of the combustion air flowing through the feed line 16 can be determined. The mass flow measuring unit 56 generates corresponding mass flow signals and feeds these to the control unit 54. In the shown example, the mass flow measuring unit 56 is arranged in the suction device 22, i.e. in the inlet region, in which the combustion air is aspirated from the surroundings.

(14) The flow direction of the combustion air and of the exhaust gases through the driving device 10 is marked by the arrows B. The designations upstream and downstream relate to this flow direction.

(15) Furthermore, the status sensor device 49 includes a tachometer 58 which measures the rotational speed of the internal combustion engine 12 converting it into corresponding rotational speed signals.

(16) The driving device 10 according to the present disclosure is operated in the following manner: as soon as the internal combustion engine 12 is started. The pressure sensor 50 measures the second pressure p.sub.z2 and converts the measured second pressure into corresponding pressure signals. Furthermore, the mass flow of the combustion air, which is sucked into the feed line 16 via the suction device 22, is determined with the mass flow measuring unit 56 which converts the mass flow into corresponding mass flow signals. In addition to this, the tachometer 58 measures the current rotational speed of the internal combustion engine 12 and converts the measured rotational speed into corresponding rotational speed signals.

(17) By way of the electrical lines 52, the pressure signals which are provided by the status sensor device 49, the mass flow signals and the rotational speed signals are fed to the control unit 54 which out of the pressure signals, the mass flow signals and/or the rotational speed signals determines a first pressure p.sub.z1 and an exhaust pressure p.sub.a using the characteristic maps already mentioned above and compares the first and the second pressure p.sub.z1, p.sub.z2 with the exhaust gas pressure p.sub.a. In case that both the first pressure p.sub.z1 and second pressure p.sub.z2 are greater than the exhaust gas pressure p.sub.a there is no driving pressure gradient from the discharge line 20 to the feed line 16. Consequently it is not possible either to recirculate the exhaust gas from the discharge line 20 into the feed line 16 without the help of a delivery unit. Accordingly, the shut-off and directional control device 44 is activated by the control unit 54 so that it completely shuts off the recirculation line 38. In this case, no exhaust gas is recirculated from the discharge line 20 into the recirculation line 38.

(18) In case that the control unit 54 based on the second pressure p.sub.z2 determined by the status sensor device 49 and in particular by the pressure sensor 50 calculates that the exhaust gas pressure p.sub.a is greater than the second pressure p.sub.z2, but smaller than the first pressure p.sub.z1, the control unit 54 activates the shut-off and directional control device 44 so that the exhaust gas is recirculated into the feed line 16 downstream of the charge air cooler by way of the bypass line 45 and the second inlet 48. Depending on how much greater the exhaust gas pressure p.sub.a is compared with the second pressure p.sub.z2, the control unit 54 additionally activates the regulating valve 42 accordingly so that the optimal flow rate of the exhaust gas is recirculated in order to be able to optimally operate the internal combustion engine 12 in particular with respect to the thermal efficiency and the quietness of operation.

(19) In case that the control unit 54 determines based on the second pressure p.sub.z2 measured by the pressure sensor 50, the mass flow of the sucked-in combustion air measured by the mass flow measuring unit 56 and/or the rotational speed of the internal combustion engine 12 measured by the tachometer 58 that the exhaust gas pressure p.sub.a is not only greater than the second pressure p.sub.z2 but also greater than the first pressure p.sub.z1, the control unit activates the shut-off and directional control device 44 so that the recirculated exhaust gas is recirculated into the feed line 16 upstream of the charge air cooler 36 via the first inlet 46 of the recirculation line 38.

(20) In both cases, the control unit activates the regulating valve 42 so that the optimal flow rate of the recirculated gas is recirculated.

(21) In FIG. 2, the differential pressure p.sub.2 between the exhaust gas pressure p.sub.a and the second pressure p.sub.z2 (.sub.p2=p.sub.ap.sub.z2) as a function of the rotational speed and the effective mean pressure BMEP (brake mean effective pressure). The load, with which the internal combustion engine is operated, can be described with the mean pressure BMEP. As already explained above, the exhaust gas pressure p.sub.a is present between the internal combustion engine 12 and the exhaust gas turbine 32 in the discharge line 20, while the second pressure p.sub.z2 is present in the feed line between the throttle valve 18 and the internal combustion engine 12.

(22) It is evident that in particular at a high load (BMEP>10 bar) and low rotational speeds (<3500 U/min) the differential pressure p.sub.2 is negative, so that no driving pressure gradient from the discharge line 20 to the feed line 16 downstream of the charge air cooler 36 is present here. The pressure differential p.sub.2 becomes positive in particular when the load is reduced (falling BMEP) and/or the rotational speeds are increased. As soon as the pressure differential p.sub.2 becomes positive, the control unit 54 switches the shut-off and directional control device 44 so that a part of the recirculated exhaust gas can flow into the feed line 16 via the second inlet 48 and downstream of the charge air cooler 36. The proportion of the recirculated exhaust gas is adjusted through suitable activation of the regulating valve 42.

(23) In FIG. 3, the pressure differential p.sub.1 between the exhaust gas pressure p.sub.a and the first pressure p.sub.z1 (p.sub.p1=p.sub.ap.sub.z1) is shown as a function of the rotational speed and the BMEP. As already explained above, the exhaust gas pressure p.sub.a is present in the discharge line 20 between the combustion engine 12 and the exhaust gas turbine 32, while the first pressure p.sub.z1 is present in the feed line 20 between the turbo compressor 30 and the charge air cooler 36. It is evident that from a rotational speed of 3,000 rpm and in particular at a high power output (BMEP>14 bar) the pressure differential p.sub.1 becomes positive. With increasing rotational speeds of the internal combustion engine 12, the pressure differential p.sub.1 becomes positive even at lower effective mean pressures BMEP. As soon as the pressure differential p.sub.1 becomes positive, the control unit 54 switches the shut-off and directional control device 44 so that the recirculated exhaust gases can be introduced into the feed line 16 upstream of the charge air cooler 36 via the first inlet 46.

(24) From FIG. 3 it is evident that the characteristic map range, in which the recirculated exhaust gases are introduced into the feed line 16 upstream of the charge air cooler 36, is relatively small. If the recirculated exhaust gases were to be permanently introduced into the feed line 16 upstream of the charge air cooler 36, a high-pressure exhaust gas recirculation could not be employed at all at rotational speeds below 3,000 rpm. In this regard, the driving device 10 according to the present disclosure makes it possible to employ the high-pressure exhaust gas recirculation in a significantly larger characteristic map range.

(25) In FIG. 4, the steps of a method according to the present disclosure and of the computer program product according to the present disclosure are shown by way of a flow diagram. In a first step, the second pressure p.sub.z2 in the feed line 16 is measured by the pressure sensor 50, which generates the pressure signals, which correspond to the measured pressure. In a further step, the pressure signals are fed to the control unit 54. In the step that then follows, the control unit 54 calculates the first pressure p.sub.z1 and the exhaust gas pressure p.sub.a by way of stored characteristic map lines and from this determines the pressure differentials p.sub.1 and p.sub.2. Depending on the outcome of the pressure differentials, the shut-off and directional control device 44 is activated so that the recirculation line 38 is completely shut off or the exhaust gas is recirculated into the feed line 16 via the bypass line 45 and via the first inlet 48 and through the charge air cooler 36 or via the second inlet 48 bypassing the charge air cooler 36.

(26) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.