Control system and method for controlling exhaust gas emission of a motor vehicle

Abstract

A method for controlling exhaust gas emission of a motor vehicle may include determining when the motor vehicle drives into a low-emission zone, wherein the low-emission zone dictates a maximum emission level for the motor vehicle; reducing actual accelerator actuation signals of the motor vehicle to effective accelerator actuation signals within the low-emission zone; and trimming an actual intake temperature of the motor vehicle, being measured with an intake temperature sensor of the motor vehicle, to an effective intake temperature when the actual intake temperature falls outside a predetermined temperature range within the low-emission zone; wherein at least one of the effective accelerator signals and the effective intake temperature are used as inputs for controlling an exhaust gas recirculation (EGR) subsystem of the motor vehicle.

Claims

1. A method of controlling exhaust gas emission of a vehicle, the method comprising: determining, by a controller, when the vehicle drives into a low-emission zone, wherein the low-emission zone is a zone limiting a maximum emission level for vehicles; reducing, by the controller, actual accelerator actuation signals of the vehicle to effective actual accelerator actuation signals within the low-emission zone; and trimming, by the controller, an actual intake temperature of the vehicle, being measured with an intake temperature sensor of the vehicle, to an effective intake temperature when the actual intake temperature falls outside a predetermined temperature range within the low-emission zone, wherein at least one of the effective actual accelerator actuation signals and the effective intake temperature are used as inputs for controlling an exhaust gas recirculation (EGR) subsystem of the vehicle.

2. The method according to claim 1, wherein the actual accelerator actuation signals are reduced to the effective actual accelerator actuation signals such that the effective actual accelerator actuation signals stay below an engine load limit within the low-emission zone.

3. The method according to claim 1, wherein the actual accelerator actuation signals are generated by an accelerator pedal of the vehicle.

4. The method according to the claim 1, wherein the predetermined temperature range defines a first temperature threshold below which the actual intake temperature is increased to the effective intake temperature and/or a second temperature threshold above which the actual intake temperature is decreased to the effective intake temperature.

5. The method according to the claim 1, wherein the determining when the vehicle drives into the low-emission zone includes receiving an entry signal with a receiving device of the vehicle, and wherein the entry signal is configured to specify that the vehicle has entered the low-emission zone.

6. The method according claim 5, wherein the entry signal is sent by a stationary sending device when the vehicle enters the low-emission zone.

7. The method according to the claim 1, further including: releasing, by the controller, a confirmation signal by the vehicle that the vehicle enters the low-emission zone when the vehicle drives into the low-emission zone.

8. The method according to claim 7, wherein the confirmation signal is a visible signal emitted by a lighting device of the vehicle.

9. The method according to the claim 1, wherein the low-emission zone corresponds to an internal city area.

10. A control system for controlling exhaust gas emission of a vehicle, the control system including: an exhaust gas recirculation (EGR) subsystem; an intake temperature sensor configured to measure an intake temperature of the vehicle; and a controller, wherein the controller is configured to determine when the vehicle drives into a low-emission zone, the low-emission zone being a zone limiting a maximum emission level for vehicles, wherein the controller is configured to reduce actual accelerator actuation signals of the vehicle to effective actual accelerator actuation signals within the low-emission zone, wherein the controller is configured to trim an actual intake temperature of the vehicle measured with the intake temperature sensor to an effective intake temperature when the actual intake temperature falls outside a predetermined temperature range within the low-emission zone, and wherein the controller is configured to control the EGR subsystem based on at least one of the effective actual accelerator actuation signals and the effective intake temperature as inputs thereof.

11. The control system according to claim 10, further including: a receiving device communicatively coupled with the controller and configured to receive an entry signal configured for specifying that the vehicle has entered the low-emission zone, wherein the controller is configured to determine that the vehicle drives into the low-emission zone when the receiving device receives the entry signal.

12. The control system according to claim 10, further including: a lighting device configured to emit a confirmation signal when the vehicle enters the low-emission zone.

13. The control system according to the claim 10, wherein the controller is configured to reduce the actual accelerator actuation signals to the effective actual accelerator actuation signals such that the effective actual accelerator actuation signals stays below an engine load limit within the low-emission zone.

14. The control system according to the claim 10, wherein the predetermined temperature range defines a first temperature threshold below which the actual intake temperature is increased to the effective intake temperature by the controller and a second temperature threshold above which the actual intake temperature is decreased to the effective intake temperature by the controller.

15. The vehicle with the control system according to the claim 10.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically depicts a motor vehicle with a control system for controlling exhaust gas emission according to an exemplary embodiment of the present invention.

(2) FIG. 2 shows a schematic plot illustrating usage of the control system of FIG. 1.

(3) FIG. 3 shows another schematic plot illustrating usage of the control system of FIG. 1.

(4) FIG. 4 shows yet another schematic plot illustrating usage of the control system of FIG. 1.

(5) FIG. 5 shows another schematic plot illustrating usage of the control system of FIG. 1.

(6) FIG. 6 shows yet another schematic plot illustrating usage of the control system of FIG. 1.

(7) FIG. 7 shows a low emission zone within a city, in which the control system of FIG. 1 is used to reduce exhaust emissions.

(8) FIG. 8 shows a flow diagram of a method for controlling exhaust gas emission with the control system of FIG. 1.

(9) It may be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the present invention. The specific design features of the present invention as included herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particularly intended application and use environment.

(10) In the figures, reference numbers refer to the same or equivalent portions of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

(11) Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the present invention(s) will be described in conjunction with exemplary embodiments of the present invention, it will be understood that the present description is not intended to limit the present invention(s) to those exemplary embodiments. On the other hand, the present invention(s) is/are intended to cover not only the exemplary embodiments of the present invention, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the present invention as defined by the appended claims.

(12) FIG. 1 schematically depicts a motor vehicle 100 with a control system 10 for controlling exhaust gas emission according to an exemplary embodiment of the present invention. A corresponding flow diagram of a method M for controlling exhaust gas emission with the control system 10 of FIG. 1 is shown in FIG. 8. The system 10 and method M are used in the present example to regulate emissions of diesel vehicles within city areas to reduce emissions and avoid banning of these or similar vehicles from the city area. The motor vehicle 100 of the present exemplary embodiment of the present invention is configured with an internal combustion engine running on diesel fuel.

(13) FIG. 7 shows an exemplary city 3, which has an internal city area which is marked as a low-emission zone 1, in which certain regulations apply with respect to emission levels. For example, an upper limit on NOx emissions may be defined for the present low-emission zone 1 so that only those vehicles may enter the internal city that are able to regulate their emissions below the present level while traveling through the city 3.

(14) Coming back to FIG. 1, the control system 10 is regulated by a control device 8 disposed in the vehicle 100 and connected on the one side to an exhaust gas recirculation (EGR) subsystem 2 and an intake temperature sensor 7 of the vehicle 100. On the other side, the control device 8 is connected to a receiving device 4, which is provided with a lighting device 6. The control system 8 is further connected to an accelerator pedal of the vehicle 100, which is not shown in FIG. 1.

(15) The intake temperature sensor 7 is configured to measure an actual intake temperature Ta of the motor vehicle 100, which is then used by the control system 8 as an input to the exhaust emission control, for controlling operation of the EGR subsystem 2. The control system 8 further receives actual acceleration actuation signals A from the accelerator pedal, which define current acceleration demands by an operator of the vehicle 100. Both, the accelerator signals and the temperature signals are used by the control system 8 as inputs for controlling the EGR subsystem 2. However, contrary to conventional systems, the actual acceleration actuation signals Aa as well as the actual intake temperature Ta are first adjusted to improve the effectivity of the EGR subsystem 2 before these are forwarded for EGR control.

(16) Normally, the volume of air recirculated by the EGR subsystem 2 through the engine is regulated depending on the actual intake temperature Ta as well as the actual accelerator actuation signals Aa. For example, at high engine loads and/or high torques, the volume of air transferred by the EGR subsystem 2 is decreased. Similarly, the EGR performance is phased down for temperatures outside an optimal working range, typically between 15 C. to 30 C. Hence, for high engine loads (corresponding to large accelerator requests) and at low/high intake temperatures, there may be a significant increase in NOx emissions due to a reduction in capacity of the EGR subsystem 2 or because this system is switched off completely. Hence, a diesel vehicle may emit NOx on a level not allowed within the low-emission zone 1.

(17) To avoid the present problem, the control device 8 of the exemplary embodiment of the present invention is configured to determine when the motor vehicle 100 drives into the low-emission zone 1. To the present end, the receiving device 4 is communicatively coupled with the control device 8 and configured to receive an entry signal 11 specifying that the motor vehicle 100 has entered the low-emission zone 1. The control device 8 on the other hand is configured to determine that the motor vehicle 100 drives into the low-emission zone 1 when the receiving device 4 receives the entry signal 11. The entry signal 11, which may be an infrared signal, a radio signal or other wireless signal, is released by a stationary sending device 5, which is disposed at a border of the low-emission zone 1, e.g., adjacent to or above a road, e.g., in a similar vein as toll collection systems. The vehicle 100 further includes a lighting device 6 being configured to emit a visible (or other) confirmation signal 9 when the motor vehicle 100 enters the low-emission zone 1 so that the stationary sending device 5 and/or a person may check that the vehicle 100 has recognized that it is entering the low-emission zone 1 and will initiate appropriate steps to stay below the required emission levels, as will be explained in the following.

(18) The control device 8 is configured to reduce the actual accelerator actuation signals Aa of the motor vehicle 100 to effective accelerator actuation signals Ae within the low-emission zone 1, to trim the actual intake temperature Ta of the motor vehicle 100 to an effective intake temperature Te when the actual intake temperature Ta falls outside a predetermined temperature range within the low-emission zone 1, and to control the EGR subsystem 2 based on the effective accelerator signals Ae and the effective intake temperature Te as inputs thereof. Hence, these adjusted effective values are used to steer the EGR subsystem 2 and not the actual values as in conventional systems.

(19) The actual accelerator actuation signals Aa are reduced to the effective accelerator actuation signals Ae such that the effective accelerator actuation signals Ae stay below an upper engine load limit within the low-emission zone 1 to avoid a reduction in EGR performance for high engine loads and/or torques. Furthermore, the predetermined temperature range defines a lower temperature threshold T1 below which the actual intake temperature Ta is increased to the effective intake temperature Te and/or an upper temperature threshold T2 above which the actual intake temperature Ta is decreased to the effective intake temperature Te. Hence, in a similar vein also the intake temperature is readjusted to avoid losing performance of the EGR subsystem 2 when driving under temperatures above or below the normal operating temperatures of the EGR subsystem 2.

(20) The method M in FIG. 8 correspondingly includes under M1 determining when the motor vehicle 100 drives into the low-emission zone 1. The method M further includes under M2 releasing the confirmation signal 9 by the motor vehicle 100 that the motor vehicle 100 enters the low-emission zone 1. The method M further includes under M3 reducing the actual accelerator actuation signals Aa of the motor vehicle 100 to the effective accelerator actuation signals Ae within the low-emission zone 1. The method M further includes under M4 trimming the actual intake temperature Ta of the motor vehicle 100 to the effective intake temperature Te when the actual intake temperature Ta falls outside the predetermined temperature range within the low-emission zone 1. The method M then utilizes the effective accelerator actuation signals Ae and the effective intake temperature Te as inputs to controlling the EGR subsystem 2.

(21) Illustrative examples for the above approach are explained with reference to FIGS. 2 to 6.

(22) In the example of FIG. 2, an accelerator OUT signal Ao is shown versus an accelerator IN signal Ai. An actual accelerator actuation signal Aa is shown next to an effective accelerator actuation signal Ae. There is a one-to-one correspondence between accelerator IN signal Ai and accelerator OUT signal Ao in a case of the actual accelerator actuation signal Aa. However, as may be seen, the effective accelerator actuation signal Ae is reduced by a fraction of 50% with respect to the actual accelerator actuation signal Aa over the whole input range. Hence, the engine of the vehicle 100 is effectively operated at a reduced performance within the low-emission zone 1 and, thus, emission levels are kept low. It is understood that the shown values are merely an example. The person of skill will readily contemplate how to reduce the actual accelerator actuation signal Aa to the effective accelerator actuation signal Ae for each application.

(23) As an exemplary embodiment of the present invention, FIG. 3 shows torque D as a function of rotation speed n for an actual accelerator actuation signal A and a reduced effective accelerator actuation signal Ae, wherein the reduced effective accelerator actuation signal Ae is limited to 50% of the maximum torque D.

(24) In a similar vein, FIG. 4 illustrates EGR operation level versus an intake temperature IN signal for an actual intake temperature Ta and an effective intake temperature Te. An upper temperature threshold T2, e.g., 30 C., and a lower temperature threshold T1, e.g., 20 C., are defined. As may be seen, the effective intake temperature Te is increased with respect to the actual intake temperature Ta below the lower temperature threshold T1 such that the EGR subsystem 2 runs on full capacity even below the lower temperature threshold T1, at least for some temperature range, e.g., down to 10 C. or less. In a similar vein, the effective intake temperature Te could be increased above the upper temperature threshold T2 (in the present example however both actual and effective intake temperatures are equal above the upper threshold T2).

(25) FIG. 5 shows another example, in which an intake temperature OUT signal is shown versus an intake temperature IN signal for both actual intake temperature Ta and effective intake temperature Te. As may be seen, the actual intake temperature Ta is decreased above an upper temperature threshold T2 and increased below a lower temperature threshold T1, wherein both thresholds T1, T2 are equal in the present specific example. Based on such an adjustment, the EGR operation region may be increased to a larger operating range.

(26) This is also demonstrated in FIG. 6, which shows torque D as well as engine power P as a function of rotation speed n for the actual values (control system off) and the effective values (control system on) of accelerator actuation signals Aa, Ae and intake temperatures Ta, Te. As may be seen, the vehicle 100 is operated at consistently lower torque D as well as engine power P in case that the present control system 10 is switched on. As a consequence, the vehicle 100 may be operated for a larger region of the parameter space within the EGR operating region E0 where the EGR subsystem 2 is switched on and/or running at full/high capacity (cf. The hatched EGR operating region E0 in FIG. 6).

(27) As a result, the control system 10 may be used to limit engine emissions without any modification to the engine itself. Instead, merely acceleration actuation and intake temperatures are adjusted to be configured to use the EGR subsystem 2 more effectively within the internal city. To this end, engine performance is deliberately reduced. The control system 10 described above may be easily retrofitted to existing vehicles by simply providing a receiving/lighting device 4, 6 (e.g., a wireless device with signal light) together with an appropriate modification at the accelerator pedal and the intake temperature sensor. The described solution thus provides an effective and cost-efficient way to reduce emissions for diesel vehicles within the city.

(28) For convenience in explanation and accurate definition in the appended claims, the terms upper, lower, inner, outer, up, down, upper, lower, upwards, downwards, front, rear, back, inside, outside, inwardly, outwardly, internal, external, inner, outer, forwards, and backwards are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. It will be further understood that the term connect or its derivatives refer both to direct and indirect connection.

(29) The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described to explain certain principles of the present invention and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the present invention be defined by the Claims appended hereto and their equivalents.