JP2017503112A - Method for estimating coolant temperature and system for cooling an automotive drive engine - Google Patents

Abstract

The invention is a method for estimating the temperature (TE) of the coolant flowing through the cooling circuit of the drive engine (2) of the automobile, a) measuring the temperature (Ts) of the coolant flowing through the first pipe of the cooling circuit. B) obtaining at least one piece of information representative of an operating parameter of the engine (2); c) the temperature of the coolant flowing through the second pipe of the cooling circuit independent of the first pipe (TE ) With the temperature (Ts) measured in step a) and the information obtained in step b). The invention further describes an engine cooling system. [Selection] Figure 1

Description

  The present invention relates generally to the cooling of automotive drive engines.

  More particularly, the invention relates to a method for estimating the temperature of a coolant circulating in a circuit that cools a drive engine of an automobile.

  The invention further relates to a system for cooling a drive engine of an automobile.

  Automobiles typically include a system for cooling a drive engine (eg, an internal combustion engine).

  Such a cooling system typically comprises at least one radiator. The function of the radiator is to cool the liquid carried through the pipe between the radiator and the cooling circuit in the engine.

  Additional elements such as air heaters, turbochargers, water oil exchangers, etc. can also be connected to the external cooling circuit formed by the radiator and the pipe.

  It is desirable to know this temperature, ideally at various points in the system, so that the operation of the assembly of these elements can be controlled within a predetermined parameter range, especially with respect to the temperature of the coolant.

  However, the use of multiple sensors incurs non-negligible costs. Thus, the sensor is often limited to only one temperature sensor, eg, positioned at the engine outlet. This impairs accurate control of the entire system.

In this context, the present invention is a method for estimating the temperature of a coolant circulating in a cooling circuit of an automobile drive engine, comprising:
a) measuring the temperature of the coolant circulating through the first pipe of the cooling circuit;
b) obtaining at least one piece of information representative of engine operating parameters;
c) estimating the temperature of the coolant circulating in the second pipe of the cooling circuit, independent of the first pipe, from the temperature measured in step a) and the information obtained in step b); We propose a method characterized by

  Therefore, the temperature of the coolant in the pipe independent of the pipe provided with the temperature sensor can be evaluated. Thus, control of the system is improved based on information conveyed by the sensor.

  The first pipe and the second pipe are pipes that connect the cooling circuit to the internal cooling circuit of the engine, for example. The first pipe may be located at the engine outlet and the second pipe may be located at the engine inlet.

According to an optional feature proposed by the invention,
The second pipe is connected to the radiator and a thermostat is arranged between the second pipe and the radiator;
The method comprises the step of estimating the temperature of the coolant in the thermostat based on the temperature estimated in the second pipe;
The temperature in the thermostat is obtained on the basis of the temperature estimated in the second pipe, with a correction utilizing at least one factor stored in the processing unit performing the step of estimating the temperature in the thermostat;
An air heater is connected to the second pipe,
The temperature in the thermostat is obtained on the basis of the temperature estimated in the second pipe, with a correction using at least one factor determined by the heating output of the air heater,
The estimation of the temperature in the second pipe uses the flow through the thermostat as determined by the thermostat course value evaluated by the thermostat course estimation module;
The obtaining step comprises receiving information representing an operating parameter of the engine originating from an engine management module;

  The invention further comprises a system for cooling a driving engine of an automobile, comprising a circuit for cooling the engine and a sensor for detecting a temperature of a coolant circulating in the first pipe of the cooling circuit, wherein the operating parameter of the engine is set. A module for obtaining at least one information to represent, a temperature measured by a sensor for the temperature of the coolant circulating through the second pipe of the cooling circuit independent of the first pipe, and the information obtained by the obtaining module A system characterized by comprising a module for estimating by the above is proposed.

Such a system may further comprise the optional features described above, in particular within the scope of the method proposed by the invention, in particular the following optional features:
The system comprises a module for estimating the temperature of the coolant in the thermostat based on the temperature estimated in the second pipe;
The module for estimating the temperature in the thermostat is based on the temperature estimated in the second pipe by means of a modification utilizing at least one coefficient stored in the processing unit implementing the module for estimating the temperature in the thermostat. Designed to determine the temperature at
The module for estimating the temperature in the thermostat is based on the temperature estimated in the second pipe so that the coefficient is determined by the heating output of the air heater and / or the temperature in the thermostat is modified using the coefficient. Designed to judge,
The temperature estimation module in the thermostat receives the thermostat course value resulting from the thermostat course estimation module and / or determines the flow through the thermostat by the course value and / or its Designed to estimate the temperature in the thermostat using flow,
The module for estimating the temperature in the second pipe is designed to receive information representing engine operating parameters arising from the engine management module;

  The following description, given by way of non-limiting example and with reference to the accompanying drawings, reveals the gist of the invention and the method of carrying out the invention.

1 schematically shows the main elements of a system for cooling an internal combustion engine. FIG. 2 schematically illustrates a controlled thermostat used in the system of FIG. It is a figure which shows the example of the system which controls this kind of thermostat. FIG. 6 shows elements of an exemplary module used to evaluate a controlled thermostat course. It is a figure which shows the example of the module which evaluates the course of a controlled thermostat. It is a figure which shows the heat exchange contained in a cooling system with a controlled thermostat and an engine. FIG. 5 is a diagram illustrating an example of a module for evaluating the temperature of a coolant in a controlled thermostat in accordance with the teachings of the invention.

  FIG. 1 shows the main elements of a system for cooling an internal combustion engine 2 of a motor vehicle. This engine is here a compression ignition (diesel) engine. In a variant, the engine may be a positive ignition (gasoline) engine.

  In FIG. 1, elements that are present in accordance with particular variations for carrying out the invention are represented by dashed lines.

  The cooling system comprises a radiator 6 which is mounted, for example, at the front of the automobile to receive the air flow generated by the movement of the vehicle, and an air heater 8 which makes it possible to heat the passenger compartment of the vehicle.

  The coolant passes through the internal combustion engine 2 and reliably operates the engine at a predetermined set point temperature as described below.

  At the exit of the engine 2, the coolant (heated by the engine 2) is carried by pipes to the thermostat 4, the radiator 6, and the air heater 8. After cooling in these elements, the coolant is carried to the engine 2 by pipes to cool the engine 2.

  Regardless of the state of the thermostat 4 (open or closed), the coolant passes through the thermostat 4 from the engine 2 (outlet) to the engine 2 (inlet) so that the thermostat 4 is always in contact with the coolant flow. Carried to forever.

  The cooling system may optionally further comprise a water oil exchanger 12 that receives coolant from the engine 2 at the inlet. After passing through the water-oil exchanger 12, the coolant is again injected into the circuit described above, for example with a thermostat 4. The use of a water oil exchanger is not within the scope of the present invention and is therefore not described in detail here.

  The coolant is a thermostatic valve that adjusts the amount of cooled coolant (from the radiator 6) injected into the inlet of the engine 2 to obtain the desired operating temperature of the engine, as described below. It is carried from the radiator 6 to the engine 2 through the thermostat 4.

  Similarly, the coolant at the exit of the engine 2 can be used to adjust the temperature within the turbocharger 14. For this purpose, the coolant is supplied to the turbocharger 14 through a branch from a circuit connecting the engine 2 and the air heater 8.

To measure the temperature T _S of the coolant at the outlet of the engine 2, the coolant pipe disposed at an outlet of the engine 2, the temperature sensor 10 is attached in addition.

In the exemplary embodiment, no means is provided for measuring the temperature of the coolant at the inlet of the engine 2 (temperature T _E ) or the temperature at the thermostat 4 (temperature T ₄ ). In a variant, as described below, a sensor for detecting the temperature in the cooling circuit, be provided near the inlet of the engine to measure the temperature T _E and, to a thermostat 4 for measuring the temperature T ₄ It is also possible to provide the reverse.

  2a and 2b show a thermostat in two separate operating positions, a first position where the thermostat closes the pipe connecting the radiator 6 to the engine 2 and a second position where the thermostat opens this pipe. 4 is shown.

  The thermostat 4 comprises a rod (or “pencil”) 20 to which an assembly formed by a brass body 22 and a valve (or poppet) 26 is slidably mounted. The space left between the body 22 and the rod 20 is filled with a heat sensitive material, here wax 24, tightly enclosed in this space delimited by the body 22, the valve 26 and the rod 20.

The thermostat 4 is positioned on the pipe connecting the radiator 6 to the engine 2 in such a manner that the main body 22 is immersed in the coolant having the temperature T ₄ at this position as shown above. The body 22 is therefore arranged downstream of the valve 26 in this pipe.

(When the engine 2 is stopped) when the temperature T ₄ of the cooling liquid in the thermostat 4 is lower than a predetermined threshold value (defined by the thermostat design), particularly cold, the wax 24 is solid, the valve 26 occupies the position illustrated in FIG. 2a to block the pipe. Therefore, the coolant from the radiator 6 is not injected into the cooling circuit of the engine 2 and therefore does not participate in cooling the engine.

When the coolant temperature T ₄ in the thermostat 4 reaches or exceeds the above-mentioned threshold, particularly due to the heating of the coolant by the engine 2 and the lack of cooling by the coolant from the radiator 6, the wax 24 is It melts and expands, thereby increasing the volume between the body 22 and the rod 20 and moving the body 22 and the rod 20 away from each other, resulting in the displacement of the valve 26 and opening the thermostat 4. The

  Thus, the coolant from the radiator 6 (cooled by the radiator 6) is injected into the cooling circuit of the engine 2 and thus participates in the cooling of the engine.

  Thus, a mechanical adjustment of the coolant temperature is obtained.

Decrease the temperature of the coolant T ₄ is, when the condensed cold wax, to the valve 26 to facilitate the return to the closed position, typically the return spring (not shown) is provided.

  The thermostat 4 further includes an electrical resistor (not shown). The electrical resistor is installed, for example, inside the rod 20 and is electrically connected to the electrode 28.

When a voltage V is applied to electrode 28, current passes through the resistor, which releases heat using the effect of Joule's law, thus accelerating the temperature increase of wax 24. Thus the thermostat 4, when there is no heating by resistors, i.e., the temperature T ₄ of the cooling fluid is rapidly released than when lower than the threshold mentioned above.

  Therefore, the adjustment temperature of the coolant of the engine 2 can be artificially lowered by using the heating of the wax 24 (using a resistor here). The thermostat 4 is a controlled thermostat.

By continuously applying the nominal voltage V ₀ (maximum effective voltage), it is possible to obtain the maximum heat generation amount (depending on the design of the thermostat) by the resistor. A calorific value lower than the maximum calorific value is obtained by applying the nominal voltage V ₀ only for part of the relevant period (pulse width modulation or PWM principle). In the following, it is assumed that an effective voltage V lower than the nominal voltage V ₀ is applied in this case.

  FIG. 3 shows an example of a system for controlling a thermostat 4 according to the teachings of the invention.

  The control system of FIG. 3 comprises several modules shown here in functional form. In practice, however, several functional modules may be implemented by the same processing unit programmed to perform the processing operations assigned to each of these functional modules. This processing unit is, for example, an engine control computer 30 (that is, ECU (“engine control unit”)) provided in the vehicle or a processing unit specialized for controlling the thermostat 4.

  Whatever the physical architecture of the thermostat control system, load information C (represented by N.m) and engine speed information N (represented by rpm) representing the operation of the engine 2 is available within the computer 30. is there.

These information C, N, on the one hand is transmitted to the module 32 to determine the temperature setpoint T _C, on the other hand is transmitted to the module 36 for evaluating the temperature T ₄ of the cooling liquid in the thermostat 4.

Setpoint determination module 32, based on the mappings stored in the processing unit to implement the module 32, to establish a temperature set point T _C according to the engine speed N and load C. In other words, the module 32 reads the values associated with the values of the engine speed N and the load C received from the computer 30 with the correspondence table (mapping) stored in the corresponding processing unit, thereby the temperature set point T _C. Designed to judge.

Setpoint determination module 32, for example, suitable for various encountered operating conditions of the engine 2 (represented by the load C and the engine speed N), the generating the set point T _C between 110 ° C. from 90 ° C.. In practice, the set point _{T C} is, 90 ° C., 100 ° C., may take a group of discrete values, such as 110 ° C..

Temperature setpoint T _C generated by the set point determination module 32 is transmitted to the adjustment module 34. The regulation module 34 also receives the coolant temperature T _{S at} the outlet of the engine as measured by the temperature sensor 10.

Based on the measured temperature T _S and the temperature set point T _C, adjusting module 34 to direct the coolant temperature to the set point T _C, the total effective voltage V _R applied to the electrodes of the controlled thermostat 4 Judging.

Adjusting method applied by regulating module 34 to determine the total effective voltage V _R in accordance with the measured temperature T _S and the temperature set point T _C is dependent on the application envisioned.

For example, in the case shown above the set point T _C can take a set of discrete values, it is possible to assume the following.
- When setpoint _{T C} is equal to 110 ° C. (high temperature adjustment), the total effective voltage _{V R} is equal to 0V. That is, the heating resistance of the wax is not used, and the adjustment of the temperature of the coolant is mechanically implemented by a thermostat (here, the design of the thermostat is aimed at adjustment at 110 ° C.).
- Setpoint T _C is strictly lower than 110 ° C. (low temperature control), so that when equal to 90 ° C. or 100 ° C. In the case described above, the total effective voltage V _R, for example, temperature by PI (proportional integral) control mechanism It is determined by the error (T _S −T _C ).

Total effective voltage V _R generated by the adjustment module 34 is transmitted to the correction module 40 illustrating a further operation below.

Module 36 for evaluating the temperature T ₄ of the cooling liquid in the thermostat 4, the inlet receives a temperature T _S measured by the measuring sensor 10, and the estimated course value L of the thermostat 4, as well as already indicated, the engine The load C and the engine speed N, which are information representing the operation of the second, are received.

  The estimated course value L of the thermostat 4 is created by a module 38 for the purpose of creating this estimated course value, as will be described in more detail below.

Based on this information received at the inlet, the module 36 evaluates the coolant temperature T ₄ in the thermostat 4, for example, in a manner that will be described in more detail below with reference to FIGS. 6 and 7.

  As mentioned above, according to a possible variant, the module 36 may be replaced by a temperature sensor immersed in the coolant in the thermostat 4.

The course evaluation module 38 described above includes the temperature T ₄ of the coolant in the thermostat (in the illustrated example, created by the evaluation module 36) and the effective voltage value that is effectively applied by the controlled thermostat 4 at the entrance. (A corrected valid value V _C generated by the correction module 40 as described below).

Based on this information received at the entrance, module 38 evaluates the course L of the relative displacement of rod 20 and body 22. Thereby, the open ratio of the thermostat 4 is estimated. The evaluation performed by module 38 is performed using, for example, a digital model as described below with reference to FIGS. 4a, 4b, and 5. In a variant, this evaluation can be performed by reading the course L associated with the value of the temperature T ₄ received at the inlet and the applied effective voltage V _C with a pre-recorded corresponding table. The pre-recorded value is determined using a prior test or simulation performed in advance, for example in this case using the digital model described with reference to FIGS. 4a, 4b, and 5 Has been.

Thus, the module 38 can provide the correction module 40 with a value L representing the course of the thermostat 4. Fixed module 40 at the entrance, further receives a total effective voltage V _R which is calculated by the adjustment module 34 as indicated previously.

Adjustment module 34 total effective voltage V _R is low, which is calculated by, or when zero, correction module 40, as the minimum effective voltage is effectively applied to the controlled thermostat 4 electrodes 28, modify this value To do. This allows the resistor to transmit a heat value not equal to zero, thus allowing the wax 24 to be preheated to the limit temperature for opening the thermostat 4. Thus, any additional heating of the wax 24 (in response to a command from the control system intended to open the thermostat) has the effect of opening the valve immediately.

In practice, thanks to the knowledge of the estimated course value L of the thermostat 4 (received from the module 38), the correction module 40 is able to determine the rate at which the thermostat 4 is opened by an effectively applied effective voltage value. it can. If the correction module 40 confirms that the thermostat 4 is closed (ie, L = 0), the correction module 40 will exit at the previous exit until a slight opening of the thermostat 4 is confirmed (still using the estimated course value L). A modified effective voltage value V _C that is slightly larger than the voltage value applied to is generated.

Of course, this mechanism for applying a minimum pre-heating voltage, the total effective voltage V _R generated by the adjustment module 34 is maintained only only between lower than this minimum preheating voltage. Virtually immediately after the regulating module 34 has ordered the total effective voltage V _R is greater than the minimum pre-heating voltage, applied without modification to the controlled thermostat fourth electrode 28 the total effective voltage V _R is the fix 40 (In this case, V _C = V _R ).

Furthermore, the correction module 40 causes a limitation of the applied effective voltage V _C (and thus the amount of heat transmitted by the resistor due to the effect of Joule's law), so that the application of this voltage V _C causes the thermostat 4 to fully open (ie In other words, heating that is greater than that leading to the course L is equal to the maximum course L _max ) is prevented. No additional heating is actually required. It also hinders the response time of the system if it is subsequently decided to close the thermostat (because additional heating of the wax 24 means cooling and potentially prolonged subsequent solidification). From).

In practice, the value L of the course of the thermostat 4 received by modification module 40 reaches a maximum course L _max, correction module 40, the controlled thermostat 4, depending on the total effective voltage V _R received from the regulator module 34 And the effective voltage V _C selected to keep the course L at its maximum value L _max is applied. For example, the dependency of the applied effective voltage V _C where the estimated course L is maintained between a predetermined value (here 0.95.L _max ) and the maximum course L _max is for this purpose. used. Therefore, in this case, the closed loop application control is referred to.

Of course, this mechanism for limiting the voltage (and hence the amount of heat delivered by a resistor) to be applied, the total effective voltage V _R generated by the adjustment module 34 only only between greater than the voltage which is the limit Maintained. In fact, as soon as the adjustment module 34 commands the lower total effective voltage V _R than the limit voltage is determined by the dependent described above, the total effective voltage V _R is changed by correction module 40 to the controlled thermostat fourth electrode 28 (In this case, V _C = V _R ).

In addition to the limits described above, it is also conceivable to cause the correction module 40 to limit the effectively applied voltage V _C for this course L value range, depending on the course L received at the entrance. .

  In effect, for some types of controlled thermostats, it is not desirable to command a large amount of heat output at a particular open position of the thermostat. This is because heating can damage the seal that reliably seals between the rod and the body-valve assembly.

For this purpose, the processing unit using the correction module 40 stores a correspondence table indicating the maximum permitted effective voltage V _max according to the course L of the thermostat. This data is provided, for example, by the thermostat manufacturer.

Therefore correction module 40, at all time points, reading the maximum allowed effective voltage V _max corresponding to the course value L received from the evaluation module 38 in table, thus determining the modified effective voltage applied.
If -V _R is lower than _{V max, V} C = _{V R}
-V _R is greater than _{V max} (or equivalent) _{if, V C =} V _max

  For the sake of simplicity, the above paragraph does not take into account possible additional restrictions on the applied effective voltage aimed at avoiding excessive overheating of the wax as proposed above. .

Except the situation described above, the correction module 40 is considered to be applied to the controlled thermostat 4 adjustment module 34 effective voltage equal to the total effective voltage V _R received at the inlet from V _C.

In practice, as already explained, a fraction of the total time is generated so that power equal to that obtained by continuous application of the required effective voltage (according to the principle of pulse width modulation or PWM) is generated. Note that a given effective voltage is applied to the thermostat 4 by applying a nominal voltage V ₀ over time.

  FIG. 4a is described herein to simulate the thermal behavior of various parts of the controlled thermostat 4 for the purpose of evaluating the course of the controlled thermostat 4, as further described below. The model used in the example is shown.

In this model, each part of the controlled thermostat 4 is represented by its mass, specific heat capacity, and temperature (considered to be uniform across the part in question). Therefore, the following is defined.
The mass m _{22 of the} body 22, the specific heat capacity C ₂₂ , and the temperature T ₂₂
The mass m _{24 of the} wax 24, the specific heat capacity C ₂₄ , and the temperature T ₂₄
The mass m _{20 of the} rod 20, the specific heat capacity C ₂₀ , and the temperature T ₂₀

Furthermore, it is envisaged that these various elements and coolants are separated by interfaces characterized by surface heat transfer coefficients and surfaces, respectively. This allows you to define:
The transfer coefficient h ₁ and the surface S _{1 for} the interface between the rod 20 and the wax 24
The transfer coefficient h ₂ and the surface S _{2 for} the interface between the wax 24 and the body 22
The transfer coefficient h ₃ and surface S _{3 for} the interface between the body 22 and the coolant at temperature T ₄

Thus, heat exchange is modeled as follows:
- resistor by Joule effect by providing a thermal power P _{J (tied} directly to the available voltage V _C applied to the controlled thermostat 4) for heating the rods.
Between the rod 20 and the wax 24, the output E ₁ = h ₁ . S ₁ . A heat exchange of (T ₂₀ -T ₂₄ ) occurs (counts positively as heat transfer from the rod 20 to the wax 24).
Between the wax 24 and the body 22, the output E ₂ = h ₂ . S ₂ . (T ₂₄ -T ₂₂ ) heat exchange occurs (counts positively as heat transfer from wax 24 to body 22).
Between the body 22 and the coolant, output E ₃ = h ₃ . S ₃ . (T ₂₂ -T ₄ ) heat exchange occurs (counts positively as heat transfer from the body 22 to the coolant).

By performing thermal equilibration for each part of the thermostat, the temperature T ₂₀ , T ₂₂ , T ₂₄ of the various parts and their variation over time (every second when the above output is expressed in W). The following equations connecting ΔT ₂₀ , ΔT ₂₂ , ΔT ₂₄ are obtained:
m ₂₀ . C ₂₀ . ΔT ₂₀ = P _J −E ₁ = P _J + h ₁ . S ₁ . _(T 24 _{-T 20)}
m ₂₄ . C ₂₄ . ΔT ₂₄ = E ₁ −E ₂ = h ₁ . S ₁ . (T ₂₀ -T ₂₄ ) + h ₂ . S ₂ . _(T 22 _{-T 24)}
m ₂₂ . C ₂₂ . ΔT ₂₂ = E ₂ −E ₃ = h ₂ . S ₂ . (T _24- T ₂₂ ) + h ₃ . S ₃ . _(T 4 _{-T 22)}

These equations, as well as _(to provide an output P _J dissipated directly by a resistor arranged in the thermostat 4) coolant evaluation of the temperature T ₄ or measured and effective voltage V _C applied to the thermostat 4 of the thermostat 4 Based on the above, it is possible to determine the temperature changes of the various parts of the thermostat at all times. For system initialization, it can be assumed that at start-up (the resistor is inactive at the preceding moment) the temperature is uniform in the thermostat 4 and has the value of the coolant temperature. That is, the initial values of T ₂₀ , T ₂₂ , and T ₂₄ are selected to be equal to the initial value of T ₄ of the coolant.

Therefore, the temperature T _{24 of the} wax 24 is known, so that the value L of the thermostat profile can be obtained directly, for example using a correspondence table showing the relationship between these two values as illustrated in FIG. 4b. it can. The data (relationship between the temperature T ₂₄ and the thermostat courses L waxes), for example, is determined by pre-testing. These tests can be provided by the thermostat manufacturer.

Similarly, when the characteristics (mass, heat capacity) and interface characteristics (surface, transfer coefficient) of the various parts of the thermostat are unknown, they can be determined by prior testing or using an experimental curve of thermostat operation. Can be judged. Various component and interface features are adapted so that the result or equivalent curve determined based on the model corresponds to the test result or experimental curve (in this case, the products m ₂₀ .C ₂₀ , m ₂₂ .C Note that it is sufficient to determine ₂₂ , m ₂₄ .C ₂₄ , and h ₁ .S ₁ , h ₂ .S ₂ , h ₃ .S ₃ , and it is not necessary to determine each feature individually) .

FIG. 5 shows an example of a module 38 for evaluating the course of a controlled thermostat using the model just described. This module is implemented, for example, in a processing unit that stores a correspondence table that specifically associates the value of the wax temperature T _{24 with} the value of the course L of the thermostat.

Module 38 measured at the inlet, as shown in the temperature T _{4 (FIG.} 3 of the cooling liquid in the thermostat 4, or evaluated by a dedicated module module 36 such as described above with reference to FIG. 7, or by the temperature sensor And the value of the effective voltage V _C applied to the thermostat 4 is received.

The module 38 includes a unit 102 for storing a current evaluation value of the temperature T ₂₂ of the main body 22, a unit 104 for storing a current evaluation value of the temperature T ₂₄ of the wax 24, and a current evaluation of the temperature T ₂₀ of the rod 20. A unit 106 for storing values. As indicated above, at the start of the evaluation process, these units are initialized with the coolant temperature value T ₄ received at the inlet.

Each iteration of the process begins with evaluating new temperature values T ₂₀ and T ₂₂ for rod 20 and body 22, respectively. This approach is taken because these elements are close to the heat source and their temperature may change from the previous iteration.

To do this, the module 38 changes the temperature T ₂₀ of the rod 20 on the basis of the current values T ₂₀ , T ₂₄ and the effective voltage V _C (received at the inlet) of the temperature in an iterative process as follows: to determine the ΔT _20.

The subtractor 148 receives the current value T ₂₀ from the unit 106 and subtracts the value from the current value T ₂₄ received from the unit 104. The value generated by the subtractor 148 is converted into h ₁ . It is multiplied by S _1. Next, a determination is made according to the value obtained at the exit of the multiplier 150 using the adder 152 and the effective voltage V _C generated by the resistor and applied to the resistor using the conversion unit 108. and output P _J are summed.

The output of summer 152 is multiplied by 1 / (m ₂₀ .C ₂₀ ) in multiplier 154 to obtain the required change ΔT ₂₀ (according to the equation given above).

The output (change ΔT ₂₀ ) of the multiplier 154 is added to the current value T ₂₀ by the adder 156. Thus, at the exit of the summer 156, it is possible to obtain a new current evaluation value of the temperature T ₂₀ of the rod 20. This value will be used by unit 106 in the next iteration (after passing retarder 116 for this purpose).

Similarly, the module 38 determines the change ΔT ₂₂ in the temperature T ₂₂ of the body 22 based on the current temperature value T ₄ (received at the inlet), T ₂₂ , T ₂₄ during the iteration as follows:

Subtractor 120 subtracts the current value _{T 22} receives from the unit 102, from the current value _{T 4} that has received the value at the entrance. Similarly, the subtractor 122 receives the current value T ₂₂ from the unit 102 and subtracts the value from the current value T ₂₄ received from the unit 104. The values generated by the subtracters 120 and 122 are respectively converted into h ₃ . Multiplied by S ₃ or h ₂ . Multiplyed by S ₂ and then summed by summer 128. The output of summer 128 is multiplied by 1 / (m ₂₂ .C ₂₂ ) in multiplier 130 to obtain the required change ΔT ₂₂ (according to the equation given above).

The output of the multiplier 130 (change ΔT ₂₂ ) is added to the current value T ₂₂ by the adder 132. As a result, a new current evaluation value of the temperature T ₂₂ of the main body 22 can be obtained at the outlet of the summer 132. This value will be used by unit 102 in the next iteration (after passing retarder 112 for this purpose).

The module 38 determines the change ΔT ₂₄ in the temperature T ₂₄ of the wax 24 based on the current temperature values T ₂₀ , T ₂₂ , T ₂₄ in an iterative process (here 1 second) as follows. Here, the temperatures T ₂₀ and T _{22 used} are just calculated temperatures as described above.

The subtractor 134 receives the current value T ₂₄ from the unit 104 and subtracts the value from the current value T ₂₂ (as just calculated) received by the summer 132. Similarly, the subtractor 136 receives the current value T ₂₄ from the unit 104 and subtracts the value from the current value T ₂₀ received from the summer 156 (just as calculated). The values generated by the subtracters 134 and 136 are respectively stored in the multiplier 138 by h ₂ . Multiplied by S ₂ or in multiplier 140 h ₁ . Multiply by S ₁ and then sum by summing unit 142. The output of summer 142 is multiplied by 1 / (m ₂₄ .C ₂₄ ) in multiplier 144 to obtain the required change ΔT ₂₄ (according to the equation given above).

The output (change ΔT ₂₄ ) of the multiplier 144 is added to the current value T ₂₄ by the adder 146. Thereby, a new current evaluation value of the temperature T ₂₄ of the wax 24 can be obtained at the outlet of the summer 146. This value will be used by unit 104 in the next iteration (after passing retarder 114 for this purpose).

  Also, the new current evaluation value of temperature T24 is based on the above-described correspondence table linking the wax temperature value and the thermostat course value, in order to convert the wax temperature value into the thermostat course value L. Transmitted at the entrance.

  Thus, an estimate of the course value L of the thermostat 4 is obtained at each iteration.

  FIG. 6 shows the heat exchange that occurs in the cooling system in the controlled thermostat and engine.

As can be seen in FIG. 1, the flow of coolant entering the engine 2 and passing through it for the purpose of cooling the engine reliably depends on the flow Q _{0 at} the outlet of the air heater (and possibly the turbocharger) and the thermostat. It is the sum of the flow Q (L) at the outlet of the thermostat depending on the course L.

Due to given heating value P (C, N) by the engine, by reheating in the engine of the flow of the coolant, the temperature of the coolant increases from a value T _E at the inlet to the value T _S in the outlet. This is interpreted by the following equation:
P (C, N) = k. [Q ₀ + Q (L)]. (T _S -T _E )
Here, k is a certain characteristic of the coolant (k = ρ.C _p , ρ is the volume capacity of the coolant, and C _p is the specific heat capacity or specific heat of the coolant).

  It should be noted that the amount of heat generated by the engine depends on the operating point of the engine defined by the load C and speed N, as shown by an expression of the form P (C, N).

For example, as presently described, with these considerations to evaluate the temperature T _E of the coolant at the inlet of the engine, then the evaluation module described above the temperature T ₄ of the cooling fluid in the controlled thermostat 4 36 It is proposed to evaluate using.

FIG. 7 thus shows an exemplary module for evaluating the coolant temperature T ₄ in the controlled thermostat.

This evaluation module is determined at the entrance using information L (here, the evaluation module 38) representing the course of the thermostat 4. An example of the evaluation module 38 is shown in FIGS. 4a, 4b and 5. As described above), information about the operating point of the engine, here the load C and the engine speed N (for example provided by the engine control unit or ECU) and here the temperature sensor 10 at the outlet of the engine. it receives the temperature T _S of that coolant.

  The processing unit that implements the module of FIG. 7 stores a mapping of the output P (C, N) transmitted by the engine to the coolant according to the load C and engine speed N. This mapping is a table showing output values P transmitted to the coolant by the engine, each associated with a C, N value pair.

  This processing unit further stores a plurality of values Q (L) of the coolant flow through the thermostat, each associated with various possible values of course L.

  Thus, based on the information received as described above, the sub-module 70 reads the processing unit's memory at any instant, thereby determining the flow Q (L) associated with the course value L received at the entrance. Determine the output P (C, N) associated with the values of load C and engine speed N received at the inlet.

Thus, the sub-module 70 evaluates the temperature T _E (t) of the coolant at the engine inlet at all times t using the model described above with reference to FIG.
T _E (t) = T _S −P (C, N) / (k. [Q ₀ + Q (L)]

The temperature information T _E (t) determined by the submodule 70 is applied to the retarder 72, the subtractor 73 (which also receives the output of the retarder 72), and the adder 76. The summer further receives the output of the subtractor 73 after multiplication by the constant b in the multiplier 75.

The output of the adder 76 is applied to a subtracter 78 with a constant a. Thus, the subtractor 78 generates an estimated value of the coolant temperature T ₄ in the thermostat 4 at the outlet. This estimate has the following values at all times:
T ₄ = T _E (t) −a + b. [T _E (t) −T _E (t−1)]

Thus, the elements described above 72,73,75,76, and arrangement of 78, determines an estimate of the temperature _{T 4} of the cooling liquid in the thermostat 4 based on the estimated value of the temperature _{T E} of the coolant at the inlet of the engine 2 The submodule 71 is formed.

In this submodule 71, a and b. The modification applied to the temperature T _E (t) by the term [T _E (t) -T _E (t-1)] states that the thermostat is provided slightly upstream of the engine inlet in the coolant circuit. It is possible to consider the fact and the fact that the temperature at the inlet of the engine is due to the combination of the coolant from the thermostat and the coolant from the air heater.

  Constants a and b can be determined by prior testing and stored in a processing unit that implements the module of FIG. In the embodiments described herein, for example, a = 4 and b = 15 (for temperatures expressed in degrees Celsius or K).

  According to a possible deformation, it is conceivable to make the parameters a and b variable according to the heat power taken out of the water by the air heater. During a prior test, the parameters a and b are in this case determined for various heating outputs of the vehicle cabin. In operation, the values a and b are determined at all times as a function of the heating power (eg, as indicated by the dedicated information received from the module that manages the heating of the cabin).

In the following description, the calculation of the evaluation of the coolant temperature T ₄ of the thermostat in accordance with the evaluation of the temperature T _E of the coolant at the inlet of the engine are presented in the form of functional modules that perform various operations. In practice, these operations can be performed by execution of a program by a processing unit that implements the module of FIG.

Claims (10)

A method for estimating a temperature (T _E ) of a coolant circulating in a circuit for cooling a drive engine (2) of an automobile,
a) measuring the temperature (T _S ) of the coolant circulating through the first pipe of the cooling circuit;
b) obtaining at least one piece of information (C, N) representing operating parameters of the engine (2);
c) the temperature (T _E ) of the coolant circulating in the second pipe of the cooling circuit independent of the first pipe, the temperature (T _S ) measured in step a), and step b And estimating with the information (C, N) acquired in (1).   The method of claim 1, wherein the first pipe and the second pipe are pipes that connect the cooling circuit to an internal cooling circuit of the engine (2). The second pipe is connected to a radiator (6), a thermostat (4) is disposed between the second pipe and the radiator, and the method includes the temperature of the coolant in the thermostat (4). The estimation method according to claim 1, comprising estimating (T ₄ ) based on the temperature (T _E ) estimated in the second pipe. The temperature (T ₄ ) in the thermostat (4) has at least one coefficient (a, b) stored in a processing unit that implements the step of estimating the temperature (T ₄ ) in the thermostat (4). The estimation method according to claim 3, wherein the estimation method is obtained based on the temperature (T _E ) estimated in the second pipe by using correction. An air heater (8) is connected to the second pipe, and the temperature (T ₄ ) in the thermostat is corrected by using at least one coefficient determined by the heating output of the air heater. The estimation method according to claim 3, wherein the estimation method is obtained based on the estimated temperature (T _E ). A system for cooling a drive engine (2) of an automobile, comprising a circuit for cooling the engine (2) and a sensor (10) for detecting the temperature of the coolant circulating through the first pipe of the cooling circuit. ,
A module (30) for obtaining at least one piece of information (C, N) representing operating parameters of the engine;
The temperature (T _E ) of the coolant circulating through the second pipe of the cooling circuit, independent of the first pipe, is acquired by the temperature (T _S ) measured by the sensor and the acquisition module. And a module (70) for estimating the information (C, N).   The cooling system according to claim 6, wherein the first pipe and the second pipe are pipes connecting the cooling circuit to an internal cooling circuit of the engine (2). The second pipe is connected to a radiator (6), a thermostat (4) is disposed between the second pipe and the radiator, and the system is configured to control the temperature of the coolant in the thermostat (4). The cooling system according to claim 6 or 7, comprising a module (71) for estimating (T ₄ ) based on the temperature (T _E ) estimated in the second pipe. The module (71) for estimating the temperature (T ₄ ) in the thermostat (4) is stored in at least one processing unit that implements the module for estimating the temperature (T ₄ ) in the thermostat (4). Designed to determine the temperature (T ₄ ) in the thermostat (4) based on the temperature (T _E ) estimated in the second pipe with a modification utilizing two coefficients (a, b) 9. The cooling system of claim 8, wherein An air heater (8) is connected to the second pipe, and the module (71) for estimating the temperature (T ₄ ) in the thermostat (4) determines a coefficient from the heating output of the air heater (8), The modification using the coefficient is designed to determine the temperature (T ₄ ) in the thermostat based on the temperature (T _E ) estimated in the second pipe. Cooling system.

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