DE60318926T2 - Control system for controlling a cooling system of an internal combustion engine of a motor vehicle - Google Patents

Abstract

The system has a closed-loop control system (14) receiving a reference signal T des related to a desired operating temperature of an engine and a signal T mis related to a measured temperature of the engine. The system (14) generates a component P (cl loop) of a drive signal. An open-loop control system receiving T des generates a component P (op loop) of the drive signal using an inverse engine-radiator thermal system model.

Description

The The present invention relates to a control system for controlling a Automotive engine-cooling system.

Known cooling systems supply cooling water to an internal combustion engine, and the engine then supplies water to the inlet of a radiator via a thermostatic control valve, and the water from the radiator is pumped back into the engine. The control valve also returns a portion of the water from the engine along a bypass line extending from the control valve to the cooling water inlet of the engine; and before the water is recirculated, other inlets may supply other user devices such as the recirculation exhaust gas cooler, passenger compartment heater, engine oil cooler, and the like, see for example the document JP 05 231149 A ,

In such control systems, the cooling water temperature is exclusively by regulates the thermostatic valve, which is by nature extremely inaccurate (some known thermostatic valves work for example on the Based on the expansion of wax, this is a bad repeatable Phenomenon, that is difficult to control).

One Failure of the valve for providing an accurate cooling water temperature control causes temperature fluctuations, so that the cooling system must often be oversized, for an acceptable cooling of the engine in all operating conditions to reach.

It It is an object of the present invention to provide a control system for Controlling a vehicle engine cooling system which has been designed to be more familiar with the disadvantages Control systems by enabling a "smart" temperature control to overcome.

According to the present invention, there is provided a control system for controlling a cooling system of a vehicle engine, wherein an internal combustion engine receives a flow F _a of cooling fluid _and supplies, via regulation means controllable by a drive signal, a flow of fluid F _u to the inlet of at least one radiator ; said control system being characterized by comprising: a closed-loop control system receiving a reference signal T _des relating to a desired operating temperature of the engine and a signal T _mis representing a measured operating temperature of the engine, the closed-loop control system generates a first component P _{cl_loop of} the drive signal; and an open-loop control system that receives at least the reference signal T _des and generates a second component P _{op_loop of} the drive _signal using a model that represents the inverse engine radiator heat system.

By the feedback control, which is introduced by the open control system, the temperature converges of the cooling fluid thus with the reference temperature.

In in the case of a slow response of the feedback control due to the physical inertia the engine radiator system, such that the value of the drive signal generated by the closed system not suitable, changing To cope with conditions the open control system reacts (that on a mathematical model based and therefore no delay subject) immediately, to generate an overall drive signal having an adequate value.

A preferred, non-limiting embodiment The invention will be described below by way of example and with reference to FIGS attached Drawings in which:

1 schematically illustrates a control system for controlling a vehicle engine cooling system in accordance with the teachings of the present invention;

2 represents modeling operations performed by the control system according to the present invention.

number 1 in 1 As a whole, it provides a control system for controlling a cooling system 2 that's with an internal combustion engine 3 a vehicle (not shown) is connected. The internal combustion engine 3 receives a flow F _a of cooling fluid (for example, water in the example described) and provides the inlet of a radiator 4 via a control valve 5 ready a stream of water F _u . The cooler 4 then provides a stream of water that flows along a pipe 6 from a pump 7 to the engine 3 is pumped back. The control valve 5 (of a known type) also carries a portion of the flow F _u along a return line 9 back, extending from the control valve 5 extends to the cooling water inlet of the engine.

The control valve 5 operates under the control of an actuator 10 which is a drive signal P from an electronic central control unit 12 receives.

The electronic central control unit 12 generates the drive signal through a closed control system 14 and an open rule system 15 ,

In particular, the closed-loop control system comprises 14 an adding node 17 in which, with the opposite sign, a signal relating to the measured operating temperature of the engine, in particular a signal representing the measured temperature T _{mis of} a cooling water flow F _u at the outlet of the engine 3 represents, as well as a reference signal _{of the} T are provided, which is representative of a desired target operating temperature of the engine, in particular a target temperature of the stream of cooling water. The adding node 17 generates an error signal T of _the -T _mis that is for a control block 20 (for example, a PID block) is provided to generate a first drive _signal component P _{cl_loop} , which is then added to an adding node 22 provided.

alternative The measured operating temperature of the engine can be determined by the temperature the metal from which the engine was made, measured at characteristic points on the engine; in In this case, the reference temperature is a target temperature of characteristic points of the engine.

A second component of the drive _signal P _{op_loop} is provided by the open control system 15 which provides information in relation to the reference signal T _des and generates the second component P _{op_loop} through a mathematical model representing the inverse engine radiator heat system.

The second component P _{op_loop also} becomes the adding node 22 which generates the drive _signal P = P _{op_loop} + P _{cl_loop} .

The way in which the two signals in 1 is added as a reference only, and is in fact to be understood as any function that, assuming two contributions, produces a combined action designed to be the control valve 5 to activate.

The open control system 15 includes a number of blocks that together define a model of the engine-radiator heat system.

In particular, the open control system includes 15 ( 2 ) a first block 30 (which will be explained below), which receives the desired value of the engine operating temperature T _des (that is, the desired cooling water temperature or the desired metal temperature at certain points on the engine) and generates the estimated value of a coefficient Kr which is in an appropriate one Model represents the heat exchanger performance of the cooler, which is required to hold the desired temperature value T _of .

The open control system 15 includes a second block 40 which receives the estimated value of the coefficient Kr and generates the cooling water flow rate value Qf contained in the radiator 4 must be physically circulated in order to maintain the desired temperature value T _des . The cooling water flow rate value may be expressed as a function of fan coil operating state (on / off), and in the case of electric blowers with continued or stepwise speed adjustment, possibly as a function of fan speed.

The open control system 15 includes a third block 50 which receives the calculated cooling water flow rate value Qf and information related to the on / off state of the blower, or in the case of continued or stepwise setting of the speed with respect to the blower speed.

In a first variation, the block calculates 50 on the basis of the received information, the opening value φ of the control valve 5 which is necessary to maintain the desired temperature value T _of .

The valve opening value does not only refer to the valve 5 in the embodiment 1 , son also on the auxiliary valves (in 1 not shown for simplicity), which control the cooling water flow in the various inlets of the cooling circuit. Variations in the opening or closing of the auxiliary valves in fact affect the cooling water flow to the radiator 4 ,

The above calculation is performed with a suitable table having an opening value φ of the valve 5 (and any auxiliary valves) for each input value Qf. The first variation is advantageously used when the speed of the pump 7 can not be adjusted independently, in this case, the flow can only by acting on the opening of the control valve 5 (and any auxiliary valves) are regulated.

In a second variation, the block calculates 50 on the basis of the received information, the pump speed ω and the opening φ of the valve 5 (and any auxiliary valves) that together secure the provision of the desired temperature value T _of . The pump speed and the opening of the valve 5 are selected to maximize a given requirement, such as minimizing consumption or reducing noise. The second variation is advantageously used when the pump 7 an independent adjustment of the speed allows, in this case, the flow can be regulated by both the opening of the control valve 5 (and any auxiliary valves) as well as the speed of the pump (electrically driven, driven by the drive shaft via friction wheels, electromagnetic clutches and the like) is acted upon.

• – S_h die Motor-Kühlwasser-Wärmeaustauschfläche;
• – H_h ist der Motor-Kühlwasser-Wärmeaustauschkoeffizient;
• – T_m ist die Motormetalltemperatur;
• – T₀ ist die Umgebungstemperatur;
• – K_cc ist ein Parameter, durch den die Wärmeleistung zu bestimmen ist, die für die Fahrgastraumklimaanlage erforderlich ist;
• – K_egr ist ein Parameter, durch den die durch den AGR-Wärmeaustauscher ausgetauschte Wärmeleistung zu bestimmen ist;
• – K_oil ist ein Parameter, durch den die durch den Ölaustauscher ausgetauschte Wärmeleistung zu bestimmen ist;
• – T_des ist die Soll-Temperatur;
• – L₀ ist die thermische Trägheit des Kühlwassers.

In particular, the first block calculates 30 the estimated value of the coefficient Kr with the equation: K r = f (p H , H H , T m , T of , T 0 , k cc , L 0 , k epsilon , k oil ) (1) Here is:

• - S _{h is} the engine-cooling water heat exchange area;
• H _h is the engine cooling water heat exchange coefficient;
• - T _m is the engine metal temperature;
• T ₀ is the ambient temperature;
• - K _cc is a parameter by which to determine the heat output required for the passenger compartment air conditioning system;
• - K _egr is a parameter used to determine the heat output exchanged by the EGR heat exchanger;
• - K _oil is a parameter used to determine the heat output exchanged by the oil exchanger;
• - T is _the target temperature;
• - L ₀ is the thermal inertia of the cooling water.

The Equation (1), as presented above, can be seen clearly on a Subgroup of the above nine input variables are based.

The equation (1) can be derived from an analytic formulation or from a data table built on trials or from a combination of the two elements. By measurements of engine sensors (or information derived from the processing thereof) whose data form an information stream "Inf1" provided to the model ( 1 ), the parameters of equation (1) may be updated continuously or in predetermined time steps, or in terms of mileage or on command.

An example of the analytical formulation of equation (1) is shown below:

• – M_m die Metallmasse;
• – C_m ist die Metall-Wärmekapazität;
• – Q_load ist die durch den Motor ausgetauschte Wärmelast;
• – S_m ist die Motorluft-Wärmeaustauschfläche;
• – H_m ist der Motorluft-Wärmeaustauschkoeffizient;
• – S_h ist die Motor-Kühlwasser-Wärmeaustauschfläche;
• – H_h ist der Motor-Kühlwasser-Wärmeaustauschkoeffizient;
• – T₀ ist die Umgebungstemperatur;
• – T_fc ist die Motorauslass-Kühlwassertemperatur;
• – K_cc ist ein Parameter, durch den die Wärmeleistung zu bestimmen ist, die für die Fahrgastraumklimaanlage erforderlich ist;
• – K_egr ist ein Parameter, durch den die durch den AGR-Wärmeaustauscher ausgetauschte Wärmeleistung zu bestimmen ist;
• – K_oil ist ein Parameter, durch den die durch den Ölaustauscher ausgetauschte Wärmeleistung zu bestimmen ist.

The engine metal temperature T _m can be measured or estimated with a suitable sensor (not shown) on the engine, in which case an equation of the following type can advantageously be used: T ^ m = f (M m , C m , Q load , P m , H m , T 0 , P H , H H , T ever , K r , K cc , K olio , K epsilon ) (2) Here is:

• - M _m the metal mass;
• C _m is the metal heat capacity;
• - Q _load is the heat _load exchanged by the engine;
• -S _m is the engine air heat exchange area;
• H _m is the engine air heat exchange coefficient;
• S _h is the engine cooling water heat exchange area;
• H _h is the engine cooling water heat exchange coefficient;
• T ₀ is the ambient temperature;
• T _fc is the engine exhaust cooling water temperature;
• - K _cc is a parameter by which to determine the heat output required for the passenger compartment air conditioning system;
• - K _egr is a parameter used to determine the heat output exchanged by the EGR heat exchanger;
• - K _oil is a parameter used to determine the heat output exchanged by the oil exchanger.

The Equation (2), as presented above, can be seen clearly on a Subgroup of the above twelve input variables are based.

The Equation (2) can be derived from a mathematical model that estimates the metal temperature determined at various characteristic points of the engine, or from a table of values previously based on test results or derived from a combination of the two elements become.

In a preferred example of a mathematical model, the metal temperature T _{m can be} estimated, advantageously with a non-linear observation device of the type below:

In particular, the second block comprises 40 a block 41 which applies the value Kr to a first table, which then provides the value Qf of the cooling water flow required by the radiator to maintain the desired temperature value T _of . The first table calculates the flow in a state where the radiator fan is off.

On the block 41 follows a block 42 which determines if the calculated flow value is below a given threshold. If this is the case, the flow measured with the first table is collected and used for the following calculations. Conversely, the block follows 42 a block 43 which applies the value Kr to a second table, which then provides the value Qf of the cooling water flow which must be physically implemented to maintain the desired temperature value T _des . The second table calculates the flow in a state in which the radiator fan is turned on, and equally in the case where the speed of the radiator fan is continuously or stepwise adjustable.

The Advantages of the control system according to the present Invention will be apparent from the foregoing description. There the system is an intelligent system, provides the control system according to the invention an all-round control of the cooling water temperature ready, reducing the efficiency All the thermal functions of the engine cooling system dependent For example, the vehicle heating system, the EGR exhaust gas cooling system and the like, is greatly improved.

At The control system as described and illustrated herein may be used entirely clearly changes be made without departing from the scope of the present Deviated from the invention.

For example, the model of the open-loop control system ( 1 ) in addition to receiving the information stream Inf1 to the controller 20 of the closed control system 14 also provide an information stream Inf2 to the controller parameters of the controller 20 to update continuously.

Of the Information stream Inf2 thus causes the parameters to be updated the controller on the basis of the information flow Inf1 of the Engine.

The information flows Inf1 and Inf2 can even deactivated in relation to certain operating conditions of the engine or highlighted.

Claims (21)

Control system for controlling a cooling system ( 2 ) of a vehicle engine, wherein an internal combustion engine ( 3 ) receives a flow F _a from cooling fluid and a flow of fluid F _u via regulating devices ( 5 ), which can be controlled by a drive signal (P), the inlet of at least one cooler ( 4 ), the control system being characterized in that it comprises: a closed-loop control system ( 14 ) receiving a reference signal T _des relating to a desired operating temperature of the engine and a signal T _mis representing a measured operating temperature of the engine, the closed loop control system producing a first component P _{cl_loop of} the drive signal and an open _loop control system ( 15 ) which receives at least the reference signal T _des and generates a second component P _{op_loop of} the drive _signal by means of a model representing the inverse engine radiator heat system. The control system of claim 1, wherein the reference signal is defined by a desired temperature of the cooling fluid and the signal T _{mis represents} a measured operating temperature of the engine cooling fluid. The control system of claim 1, wherein the reference signal is defined by a desired temperature of characteristic points of the engine and the signal T _{mis represents} a measured temperature of the metal of the engine. Control system according to claim 1, wherein the closed-loop control system ( 14 ) a first adding node ( 17 ), to which the reference signal T _des and the signal T _{mis are provided} with opposite signs, the first adding node ( 17 ) generates an error signal which is fed into the control device ( 20 ), which generates the first component PP _{cl_loop of} the drive signal. Control system according to claim 4, wherein a second adding node ( 22 ) receiving the first and second components of the drive signal to generate the drive signal. A control system according to claim 1, wherein the open-loop control system comprises first calculation means ( 30 ) which produce the desired temperature value T of _the received and estimated values of a coefficient Kr for determining the performance of the radiator with respect to external heat exchange and which must be physically implemented to maintain the desired temperature value T _des , Control system according to claim 6, wherein the open-loop control system ( 15 ) second calculation means ( 40 ), which receive the value of the coefficient Kr and generate the value Qf of the cooling fluid flow that must be physically circulated in the radiator to maintain the desired temperature value T _of . The control system of claim 7, wherein the cooling fluid flow value Qf as a function of the operating state (ON / OFF) of the blower associated with the radiator or the continuous or stepwise adjustable speed of the blower expressed becomes. Control system according to claim 7 or 8, wherein the open-loop control system ( 15 ) third calculation facilities ( 50 ) receiving the cooling fluid flow value and based on information provided at their inputs, the opening value of the regulation means ( 5 ) Generate, through which the desired temperature value T _of is maintained. Control system according to claim 7 or 8, wherein the open-loop control system ( 15 ) third calculation facilities ( 50 ) receiving the calculated cooling fluid flow value Qf and, based on information provided at their inputs, the speed of a pump of the cooling system and the opening of the regulation means ( 5 ), which together ensure the provision of the desired temperature value T _of . Control system according to claim 6, wherein the first calculation means ( 30 ) the estimated Value of the coefficient Kr using an equation K r = f (p H , H H , T m , T of , T 0 , k cc , L 0 , k epsilon , k oil ) (1) which is based on at least two of the following variables: S _h , which represents the engine cooling fluid heat exchange area; - H _h , which represents the engine cooling fluid heat exchange coefficient; T _m , which represents the engine metal temperature; T ₀ , which represents the ambient temperature; - K _cc , which is a parameter by which to determine the heat output required for the passenger compartment air conditioning system; - K _egr , which represents a parameter by which to determine the heat output exchanged by the EGR heat exchanger; - K _oil , which is a parameter used to determine the heat output exchanged by the oil exchanger; - T _of which represents the target temperature; - L ₀ , which represents the thermal inertia of the cooling fluid. A control system according to claim 11, wherein the equation is analytical. A control system according to claim 11, wherein the equation includes a database built on experiments. A control system according to claim 11, wherein the equation is of the following type:

Control system according to claim 11, wherein the metal temperature T _{m is} measured by means of a sensor on the motor. A control system according to claim 11, wherein the metal temperature T _{m is determined} by means of an equation T ^ m = f (M m , C m , Q load , P m , H m , T 0 , P H , H H , T ever , K r , K cc , K olio , K epsilon ) (2) which is based on at least two of the following variables: M _m , which represents the metal mass; C _m , which represents the metal heat capacity; Q _load , which represents the heat _load exchanged by the engine; S _m , which represents the engine air heat exchange area; - H _m , which represents the engine air heat exchange coefficient; S _h , which represents the engine cooling fluid heat exchange area; - H _h , which represents the engine cooling fluid heat exchange coefficient; T ₀ , which represents the ambient temperature; T _{mis representing} the engine outlet coolant fluid temperature; - K _cc , which is a parameter by which to determine the heat output required for the passenger compartment air conditioning system; - K _egr , which represents a parameter by which to determine the heat output exchanged by the EGR heat exchanger; - K _oil , which is a parameter by which to determine the heat output exchanged by the oil exchanger. A control system according to claim 16, wherein the equation (2) based on a mathematical model that determines the metal temperature determined at various characteristic points of the engine. A control system according to claim 16, wherein the equation (2) based on a database based on test measurements was read. A control system according to claim 7, wherein the second calculation means ( 40 ) comprise: a first table, based on a received value of the coefficient Kr, of the value Qf of the cooling flux id flow that is required to hold the desired temperature value T _des , wherein the first table calculates the cooling fluid flow rate in a state where the fan associated with the radiator is turned off, and 42 ) to determine whether the calculated cooling fluid flow value is below a given threshold, if it is, the cooling fluid flow obtained using the first table is obtained and used in the model; conversely, a second table is selected that determines the value Qf of the cooling fluid flow required to hold the desired temperature value T _des for the radiator, the second table calculating the cooling fluid flow in a state where the blower associated with the radiator is turned on. A control system according to claim 1, wherein the model of the open-loop control system ( 15 ) receives a number of information items (Inf1) detected on the engine and updates the model based on the information items. A control system according to claim 20, wherein the model comprises an information stream (Inf2) for a controller ( 20 ) of the closed-loop system ( 14 ) to continuously update the control parameters of the controller.