Patent Description:
An internal combustion engine of today is generally connected to an exhaust gas after treatment system. Purely by way of example, such an exhaust gas after treatment system may comprise at least one of the following components: an oxidation catalyst, a particle filter and a selective catalytic reduction arrangement. Moreover, an internal combustion engine may further comprise an exhaust gas recirculation arrangement in order to reduce nitrogen oxide emissions from the internal combustion engine.

Various components of the exhaust gas after treatment system may have to attain a temperature above a certain threshold temperature in order to function properly. Generally, the exhaust gas after treatment system is heated by the exhaust gases from the internal combustion engine. However, in operating conditions in which the temperature ambient of the internal combustion engine is low there is a risk that the exhaust gases are not sufficiently heated in order to arrive at a preferred temperature of the exhaust gas after treatment system within a reasonable time.

In order to heat the exhaust gas after treatment system, <CIT> proposes controlling the fuel injection to an internal combustion engine to a rich side. However, such a control will increase the fuel consumption of the internal combustion engine.

According to its abstract, <CIT> discloses an engine control device for controlling an exhaust gas recirculation operation including a variable-capacity turbo supercharger, an EGR valve, a supercharging pressure controller, an EGR controller, and an EGR correction amount calculator. The variable-capacity turbo supercharger has an adjustable nozzle for varying an entrance area of an exhaust turbine and is operable to change a supercharging pressure in accordance with the opening degree of the adjustable nozzle. The EGR valve adjusts an exhaust reflow amount of exhaust gas flowing from an exhaust passage to an air intake passage. The supercharging pressure controller drives the adjustable nozzle to control the supercharging pressure. The EGR controller drives the EGR valve to control the exhaust gas recirculation operation. The EGR correction amount calculator calculates an EGR correction amount that defines an effect of the opening degree variation of the adjustable nozzle on the exhaust gas recirculation operation. The EGR controller performs a feedback control operation on the EGR valve in accordance with a deviation between an EGR control amount corrected by the EGR correction amount and a target EGR control amount.

According to its abstract, <CIT> relates to a control device for an internal combustion engine includes: a variable valve timing portion changing a phase of opening and closing of each of an intake valve and an exhaust valve into a target phase; an EGR valve adjusting an exhaust gas recirculation amount recirculated from an exhaust side to an intake side; a supercharging efficiency control portion controlling a supercharging efficiency of a supercharger; a throttle valve adjusting an intake air amount; and the internal combustion engine feedback-controls at least two of the EGR valve, the supercharging efficiency control portion, and the throttle valve, and feedforward-controls the variable valve timing portion.

One object of the present disclosure is to provide an internal combustion engine control system that can control the internal combustion engine such that appropriate emission levels are obtained in a fuel efficient way even when the internal combustion engine is operated in cold environments.

This object is achieved by a control system according to claim <NUM>.

As such, the present disclosure relates to an internal combustion engine accordingto appended claim <NUM>.

An internal combustion engine according to present disclosure implies that the boost pressure may be controlled on the basis of certain conditions, such as conditions of the environment ambient of the internal combustion engine. The above control of the boost pressure in turn implies that the mass flow through the internal combustion engine may be controlled. The mass flow through the internal combustion engine will in turn affect the temperature of the exhaust gas after treatment system. Consequently, by virtue of the control system according to the present disclosure, it is possible to at least indirectly control the temperature of the exhaust gas after treatment system without the need of providing excess fuel to the internal combustion engine and/or the exhaust gases.

Moreover, by virtue of the fact that the amount of recirculated exhaust gas via the exhaust gas recirculation assembly is controlled by an exhaust gas recirculation controller that has a response time that differs from the response time of the boost pressure controller, the flow through the exhaust gas recirculation assembly may be controlled with a low risk that the boost pressure controller and the exhaust gas recirculation controller may obtain an oscillating condition. As such, the above discussed difference in response times implies that the nitrogen oxide emissions from the internal combustion engine may be controlled in an appropriate manner at the same time as the mass flow through the internal combustion engine is controlled.

Optionally, the first response time is at least three times greater, alternatively at least five times greater or optionally at least ten times greater, than the second response time.

A difference in the response times above any one of the above discussed limits implies an appropriately low risk of obtaining oscillations in the system.

Optionally, the control system is adapted to receive a signal indicative of a condition of the environment ambient of the internal combustion engine and to issue the boost pressure control signal in response to the condition of the environment ambient of the internal combustion engine.

The issuance of a boost pressure control signal in response to the condition of the environment ambient of the internal combustion engine implies that the mass flow through the internal combustion engine may be controlled with due regard to ambient conditions, such as the ambient temperature and/or the ambient pressure. The above control in turn implies that the internal combustion engine may be controlled such that a desired temperature of the exhaust gas after treatment system may be arrived at within a reasonable time.

Optionally, the control system is configured such that when the control system receives a signal indicative of a predetermined first condition of the environment ambient, the control system issues a control signal indicative of a first boost pressure and when the control system receives a signal indicative of a predetermined second condition of the environment ambient, which second ambient condition differs from the first ambient condition, the control system issues a control signal indicative of a second boost pressure, the second boost pressure differs from the first boost pressure.

Optionally, the condition of the environment ambient of the internal combustion engine comprises the ambient temperature.

Optionally, the control system is configured such that when the control system receives a signal indicative of a predetermined first ambient temperature, the control system issues a control signal indicative of a first boost pressure and when the control system receives a signal indicative of a predetermined second ambient temperature, which second ambient temperature is lower than the first ambient temperature, the control system issues a control signal indicative of a second boost pressure. The second boost pressure is lower than the first boost pressure.

Controlling the boost pressure as a function of the temperature as has been described hereinabove implies that an improved efficiency may be obtained for the internal combustion engine, in particular when the internal combustion engine is operated in a cold climate. The improved efficiency emanates from the capability of modifying the mass flow through the internal combustion engine in response to the ambient temperature.

Optionally, the control system is also adapted to receive a signal indicative of an engine operation point of the internal combustion engine. The control system is adapted to issue the boost pressure control signal in response the condition of the environment ambient of the internal combustion engine and the engine operation point.

Optionally, the control system comprises a map look up function comprising a plurality of desired boost pressures for different predetermined conditions of the ambient environment.

Optionally, the control system comprises map look up function comprising a plurality of desired amounts of recirculated exhaust gas via the exhaust gas recirculation assembly for different predetermined conditions of the ambient environment.

The internal combustion engine comprises a boost pressure regulator and the control system is adapted to issue the boost pressure control signal to the boost pressure regulator.

Optionally, the boost pressure regulator comprises a variable geometry turbine and the control system is adapted to issue the boost pressure control signal comprising information indicative of a desired geometry of the variable geometry turbine.

Controlling the boost pressure when the boost pressure regulator comprises a variable geometry turbine implies that the pumping resistance of the turbine may be reduced for certain operating conditions. Such a pump resistance reduction may in turn result in a reduction of the fuel consumption. The above reduction of the pumping resistance may be advantageous when the geometry of the variable geometry turbine is controlled in response to the temperature ambient of the internal combustion engine.

Optionally, the boost pressure regulator comprises an inlet throttle valve and the control system is adapted to issue the boost pressure control signal comprising information indicative of a desired position of the inlet throttle valve.

Optionally, the boost pressure controller comprises a boost pressure PID controller.

Optionally, the exhaust gas recirculation controller comprises an exhaust gas recirculation PID controller.

Optionally, the control system is adapted to issue an exhaust gas recirculation control signal to at least an exhaust gas recirculation regulator.

Optionally, the exhaust gas recirculation regulator comprises an exhaust gas recirculation valve.

A second aspect of the present disclosure relates to a vehicle comprising an internal combustion engine according to the first aspect of the present disclosure.

It should be noted that the appended drawings are not necessarily drawn to scale and that the dimensions of some features of the present invention may have been exaggerated for the sake of clarity.

The invention will below be described for a vehicle in the form of a truck <NUM> such as the one illustrated in <FIG>. The truck <NUM> should be seen as an example of a vehicle which could comprise a control system according to the present invention. However, the control system of the present invention may be implemented in a plurality of different types of objects, e.g. other types of vehicles. Purely by way of example, the control system could be implemented in a truck, a tractor, a car, a bus, a work machine such as a wheel loader or an articulated hauler or any other type of construction equipment. The truck <NUM> comprises an internal combustion engine <NUM>.

<FIG> schematically illustrates the internal combustion engine <NUM>. The internal combustion engine <NUM> comprises an engine block <NUM> which in turn may comprise a plurality of piston cylinders <NUM> with an inlet manifold <NUM> and an exhaust manifold <NUM>.

Moreover, the <FIG> internal combustion engine <NUM> comprises a turbocharging unit <NUM>. The turbocharging unit comprises a turbine <NUM> which is operatively connected, for instance via a turbine shaft <NUM>, to a compressor <NUM>. Exhaust gases are led from the exhaust manifold <NUM> to the turbine <NUM> via an exhaust conduit <NUM>. Moreover, the compressor <NUM> may be in fluid communication with an intake line <NUM> and the inlet manifold <NUM> such that compressed air may be supplied from the intake line <NUM> to the inlet manifold <NUM> via an inlet conduit assembly <NUM>. Purely by way of example, the inlet conduit assembly <NUM> may comprise an intercooler <NUM>.

The embodiment of the internal combustion engine <NUM> illustrated in <FIG> comprises a boost pressure regulator <NUM> adapted to regulate the boost pressure at the inlet manifold <NUM>. As a non-limiting example, the turbocharging unit <NUM> may form a part of the boost pressure regulator <NUM>.

Instead of, or in addition to the above discussed turbocharging unit <NUM>, the boost pressure regulator <NUM> may comprise a wastegate assembly <NUM>. The wastegate assembly <NUM> is adapted to divert at least a portion of the exhaust gases from the turbine <NUM>. Purely by way of example, the wastegate assembly <NUM> may comprise a wastegate valve <NUM>'.

Instead of, or in addition to the turbocharging unit <NUM> and/or the wastegate assembly <NUM>, the boost pressure regulator <NUM> may comprise an intake throttle valve <NUM> that forms part of the inlet conduit assembly <NUM>.

Exhaust gases that have passed through the turbocharger unit <NUM> are led into the atmosphere via an exhaust line <NUM>. Furthermore, the <FIG> internal combustion engine <NUM> comprises an exhaust gas recirculation assembly <NUM> such that at least a portion of the exhaust gases may be returned to the inlet manifold <NUM> via the exhaust gas recirculation assembly <NUM>. Purely by way of example, the exhaust gas recirculation assembly <NUM> may comprise an exhaust gas recirculation cooler <NUM>. Moreover, as another non-limiting example, the exhaust gas recirculation assembly <NUM> may comprise an exhaust gas recirculation regulator <NUM> which in <FIG> is exemplified as a regulator <NUM> that comprises an exhaust gas recirculation valve <NUM>.

As may be gleaned from <FIG>, the embodiment of the internal combustion engine <NUM> illustrated therein further comprises a control system <NUM> for controlling the internal combustion engine <NUM>. The control system <NUM> may be adapted to communicate with at least the boost pressure regulator <NUM> and possibly also with the exhaust gas recirculation regulator <NUM>. Purely by way of example, the above discussed communication may be achieved by means of electrical cables (indicated by dotted lines in <FIG>) and/or by wireless communication. It should be noted that the possible communications indicated in <FIG> should be regarded as a non-limiting example only. In other embodiments of the internal combustion engine <NUM>, the control system <NUM> may be adapted to communicate with more or fewer components of the engine <NUM>.

The <FIG> embodiment of the internal combustion engine <NUM> comprises a sensor <NUM> for sensing the boost pressure and/or the boost temperature. Purely by way of example, and as is indicated in the <FIG> embodiment, such a sensor may be located in the inlet manifold <NUM>. The boost pressure sensor <NUM> may be adapted to communicate with the control system <NUM>, for instance via an electrical cable and/or by wireless communication. As a non-limiting example, the boost pressure sensor <NUM> may be adapted to provide a measured output signal, indicative of the boost pressure and/or the boost temperature, to a feedback controller of the control system <NUM>.

Furthermore, the embodiment of the internal combustion engine <NUM> illustrated in <FIG> comprises a flow sensor <NUM> adapted to determine the flow through the exhaust gas recirculation assembly <NUM>. As a non-limiting example, the flow sensor <NUM> may comprise a venturi tube. The flow sensor <NUM> may be adapted to communicate with the control system <NUM>, for instance via an electrical cable and/or by wireless communication. As a non-limiting example, the flow sensor <NUM> may be adapted to provide a measured output signal, indicative of e.g. a flow rate through the exhaust gas recirculation assembly <NUM>, to a feedback controller of the control system <NUM>.

Moreover, the <FIG> embodiment of the internal combustion engine comprises an ambient environment sensor <NUM>. The ambient environment sensor <NUM> may be adapted to detect a condition of the environment ambient of the internal combustion engine <NUM>. Moreover, the ambient environment sensor <NUM> may be adapted to issue a signal indicative of the condition thus detected to the control system <NUM>. Purely by way of example, the ambient environment sensor <NUM> may be adapted to detect at least one of the following ambient conditions: temperature, pressure and humidity.

<FIG> further illustrates that the internal combustion engine <NUM> may be connected to an exhaust gas after treatment system <NUM>. Purely by way of example, the exhaust gas after treatment system <NUM> may comprise at least one of the following components: an oxidation catalyst 11A, a particle filter 11B and a selective catalytic reduction arrangement 11C. The internal combustion engine <NUM> and the exhaust gas after treatment system <NUM> may form an internal combustion engine system.

<FIG> illustrates another embodiment of the internal combustion engine <NUM>. The <FIG> internal combustion engine <NUM> is similar to the <FIG> internal combustion engine <NUM>. However, in contrast to the <FIG> engine <NUM>, the turbocharging unit <NUM> of the <FIG> engine <NUM> comprises a variable geometry turbine <NUM>. Purely by way of example, a variable geometry turbine <NUM> may comprise one or more pivotable guide vanes (not shown) and/or one or more slidable walls (not shown) which may be used for altering the effective aspect ratio of the turbocharging unit <NUM>.

As such, in the <FIG> implementation of the internal combustion engine <NUM>, the boost pressure regulator <NUM> may comprise the variable geometry turbine <NUM> such that the boost pressure may be regulated by regulating the geometry, for instance the position of the guide vane(s) and/or the slidable wall(s), of the variable geometry turbine <NUM>.

<FIG> illustrates an embodiment of the control system <NUM>. The <FIG> embodiment of the control system <NUM> is adapted to issue a boost pressure control signal to the boost pressure regulator <NUM>. The control system comprises a boost pressure control system <NUM> adapted to determine the boost pressure control signal.

Moreover, the <FIG> control system <NUM> is also adapted to issue an exhaust gas recirculation control signal for controlling an amount of recirculated exhaust gas via the exhaust gas recirculation assembly (not shown in <FIG>). The <FIG> embodiment of the control system <NUM> is adapted to issue the exhaust gas recirculation control signal to the exhaust gas recirculation regulator <NUM>. However, other embodiments of the control system <NUM> may be adapted to issue the exhaust gas recirculation control signal to other components of an internal combustion engine (not shown in <FIG>) in order to directly or indirectly control the amount of recirculated exhaust gas via the exhaust gas recirculation assembly.

Moreover, the control system <NUM> comprises an exhaust gas recirculation control system <NUM> adapted to determine the exhaust gas recirculation control signal independently of the boost pressure control signal.

Preferably, the control system <NUM> is adapted to receive a signal <NUM> indicative of a condition of the environment ambient of the internal combustion engine and to issue the boost pressure control signal in response to the condition of the environment ambient of the internal combustion engine. Purely by way of example, such a signal <NUM> may be issued from the ambient environment sensor <NUM> illustrated in <FIG> or <FIG>.

Purely by way of example, the above discussed ambient environment control signal <NUM> may be sent to a boost pressure feedforward control <NUM> of the boost pressure control system <NUM>. Purely by way of example, the boost pressure feedforward control <NUM> may comprise a look up function. Moreover, the boost pressure control system <NUM> may comprise a boost pressure controller <NUM>. The boost pressure controller <NUM> may be a feedback controller. Purely by way of example, the boost pressure controller <NUM> may comprise a PID controller, i.e. a Proportional Integral Derivative controller. Alternatively, the boost pressure controller <NUM> may comprise a P (Proportional) controller or a PI (Proportional Integral) controller.

The boost pressure controller <NUM> has a first response time T<NUM>. Purely by way of example, the first response time T<NUM> may be equal to or above <NUM>, alternatively equal to or above <NUM>.

As used herein, the expression "response time" relates to the time elapsed from the application of an instantaneous step input to the time at which the controller output has reached and remained within an error band of <NUM>% of the magnitude of the instantaneous step.

In a similar vein, the exhaust gas recirculation control system <NUM> may also be adapted to receive a second signal <NUM> indicative of a condition of the environment ambient of the internal combustion engine and to issue the exhaust gas recirculation in response to the condition of the environment ambient of the internal combustion engine.

Purely by way of example, the above discussed second ambient environment control signal <NUM> may be the same as the first ambient environment control signal <NUM>. Moreover, as a non-limiting example, the second ambient environment control signal <NUM> may be sent to an exhaust gas recirculation feedforward control <NUM> of the exhaust gas recirculation control system <NUM>. Purely by way of example, the exhaust gas recirculation feedforward control <NUM> may comprise a look up function. Moreover, the exhaust gas recirculation control system <NUM> may comprise an exhaust gas recirculation controller <NUM>. The exhaust gas recirculation controller <NUM> may comprise a feedback controller. Purely by way of example, the exhaust gas recirculation controller <NUM> may comprise a PID controller. Alternatively, the exhaust gas recirculation controller <NUM> may comprise a P controller or a PI controller.

The exhaust gas recirculation controller <NUM> has a second response time T<NUM>. The first response time T<NUM> differs from the second response time T<NUM>. Purely by way of example, the second response time T<NUM> may be equal to or below <NUM>, alternatively equal to or below <NUM>.

Purely by way of example, the first response time T<NUM> is at least three times greater than the second response time T<NUM>. Other non-limiting examples are that the first response time T<NUM> is at least five times, preferably at least ten times, greater than the second response time T<NUM>.

At least one, though preferably both, the first and second ambient environment control signals <NUM>, <NUM> may comprise information as regard the ambient temperature and/or the ambient pressure.

In a similar vein, at least one, though preferably both, of the boost pressure control system <NUM> and the exhaust gas recirculation control system <NUM> may be adapted to receive an engine control signal <NUM>, <NUM> indicative of the operation of the internal combustion engine. Purely by way of example, the engine control signal <NUM>, <NUM> may comprise information indicative of the engine speed and/or the engine torque. Moreover, the engine control signal <NUM>, <NUM> may comprise information indicative of level of emissions produced by the internal combustion engine.

As has been intimated hereinabove when presenting the embodiment of the internal combustion engine that is illustrated in <FIG> or <FIG>, the boost pressure regulator <NUM> may comprise at least one of the following components: a variable geometry turbine, a wastegate assembly and an intake throttle valve. As such, the boost pressure control system <NUM> may be adapted to transmit the boost pressure control signal to the component or components that form part of the boost pressure regulator <NUM>.

In the non-limiting example when the boost pressure regulator <NUM> comprises a variable geometry turbine <NUM>, such as in the <FIG> embodiment of the internal combustion engine <NUM>, the control system <NUM>, using the boost pressure control system <NUM>, is adapted to issue boost pressure control signal that comprises information indicative of a desired geometry of the variable geometry turbine.

In the event that the boost pressure regulator comprises an inlet throttle valve, the control system <NUM> is adapted to, instead of, or in addition to, issuing a boost pressure control signal that is indicative of a desired geometry of the variable geometry turbine, issue a boost pressure control signal comprising information indicative of a desired position of the inlet throttle valve.

Moreover, in the <FIG> embodiment of the control system <NUM>, the exhaust gas recirculation control system <NUM> is adapted to issue a signal to the exhaust gas recirculation regulator <NUM>, e.g. to an exhaust gas recirculation valve <NUM>.

<FIG> further illustrates that the boost pressure control system <NUM> is adapted to receive a measured boost pressure signal <NUM>. Purely by way of example, the measured boost pressure signal <NUM> may be determined using the boost pressure sensor <NUM> in <FIG>.

Moreover, and as may be gleaned from <FIG>, the boost pressure controller <NUM> may use signals from the boost pressure feedforward control <NUM>, the exhaust gas recirculation regulator <NUM> and the boost pressure regulator <NUM> as control signals that are compared to the measured boost pressure signal <NUM>.

In a similar vein, the exhaust gas recirculation control system <NUM> may be associated with an exhaust gas recirculation level model <NUM> that is adapted to issue an exhaust gas recirculation level signal to the exhaust gas recirculation control system <NUM>. To this end, the exhaust gas recirculation level model <NUM> is adapted to receive a one or more signals <NUM> that can be used for determining the present exhaust gas recirculation level. Purely by way of example, the signal <NUM> may be issued from the flow sensor <NUM> illustrated in <FIG> or <FIG>.

The exhaust gas recirculation level model <NUM> may be a theoretical model that may use one or more map look up functions and/or one or more discrete or continuous functions. Purely by way of example, the one or more signals may comprise one or more of the following: a measured boost pressure, a measured boost temperature, a measured exhaust gas recirculation flow, a measured exhaust gas recirculation temperature and an amount of injected fuel.

<FIG> illustrates another embodiment of the control system <NUM> which embodiment is similar to the <FIG> embodiment. However, as compared to the <FIG> embodiment, the exhaust gas recirculation control system <NUM> is in <FIG> adapted to issue a signal to the boost pressure regulator <NUM>. As such, the <FIG> embodiment of the control system <NUM> uses the fact that a change of the boost pressure regulator <NUM> may have an influence on the amount of exhaust gas that is recirculated via the exhaust gas recirculation assembly.

As such, in the embodiment illustrated in <FIG>, both the boost pressure control system <NUM> and the exhaust gas recirculation control system <NUM> issue control signals to the boost pressure regulator <NUM>.

<FIG> illustrates a further embodiment of the control system <NUM> in which the exhaust gas recirculation control system <NUM> is adapted to issue a first signal to the exhaust gas recirculation regulator <NUM> and a second signal to the boost pressure regulator <NUM>. Purely by way of example, in an embodiment of the control system <NUM> such as the one illustrated in <FIG>, the signal issued from the exhaust gas recirculation control system <NUM> to the boost pressure regulator <NUM> may be inversely proportional to the signal that is issued from the exhaust gas recirculation control system <NUM> to the exhaust gas recirculation regulator <NUM>. As such, if the signal issued to the exhaust gas recirculation regulator <NUM> is indicative of an increased exhaust gas recirculation flow, the signal to the boost pressure regulator <NUM> may be indicative of a decreased boost pressure. Thus, in the non-limiting example wherein the internal combustion engine comprises a variable geometry turbine <NUM> and an exhaust gas recirculation valve <NUM>, if the exhaust gas recirculation control system <NUM> issues a signal to further open the an exhaust gas recirculation valve <NUM>, the exhaust gas recirculation control system <NUM> may also issue a signal to close the variable geometry turbine <NUM>.

Claim 1:
An internal combustion engine (<NUM>) comprising a control system (<NUM>), said internal combustion engine (<NUM>) comprising a turbocharging unit (<NUM>) and an exhaust gas recirculation assembly (<NUM>), said control system (<NUM>) being adapted to issue a boost pressure control signal, said control system (<NUM>) comprising a boost pressure controller (<NUM>) adapted to determine said boost pressure control signal, said boost pressure controller (<NUM>) having a first response time (T<NUM>), said control system (<NUM>) being adapted to issue an exhaust gas recirculation control signal for controlling an amount of recirculated exhaust gas via said exhaust gas recirculation assembly (<NUM>), wherein said internal combustion engine (<NUM>) comprises a boost pressure regulator (<NUM>), said control system (<NUM>) being adapted to issue said boost pressure control signal to said boost pressure regulator (<NUM>), said control system (<NUM>) comprising an exhaust gas recirculation control system (<NUM>) which in turn comprises an exhaust gas recirculation controller (<NUM>) adapted to determine said exhaust gas recirculation control signal independently of said boost pressure control signal, said exhaust gas recirculation controller (<NUM>) having a second response time (T<NUM>), wherein said first response time (T<NUM>) differs from said second response time (T<NUM>), characterized in that said exhaust gas recirculation control system (<NUM>) is adapted to issue a control signal to said boost pressure regulator (<NUM>).