FR2712979A1 - Method and apparatus for determining the exhaust gas temperature with a lambda probe used in a motor vehicle or a heating installation - Google Patents

Abstract

a) Method and device for determining the temperature of the exhaust gases with a lambda probe used in a motor vehicle or a heating installation "b) Method characterized in that the lambda probe (104) is set to a constant temperature and in that the temperature of the exhaust gases (TAbg) is determined from the electric power supplied (P) and device characterized in that there is a regulator (108) serving to adjust the temperature of the lambda probe to a predefined value and an operating block (110) which determines the exhaust gas temperature (TAbg) from the electrical power (P) supplied to the heating element (106) of the probe lambda (104).

Description

"Method and device for determining the temperature of gases

  The present invention relates to a method for determining the temperature of the exhaust gas with an exhaust gas with a lambda probe used in a motor vehicle or a heating system.

  electrically heated lambda probe.

  It is known from DE-OS 3 835 852 to determine the temperature of the exhaust gases using

  a lambda probe. In this document we measure the resistance

  internal temperature of the lambda probe and using a known relationship between the internal resistance and the temperature of the exhaust gas, the temperature of the exhaust gas is determined. This known method can be used in the case of unheated lambda probes and in the case of lambda probes which are permanently heated with a power

constant heating.

  The invention relates to a method and a device

  tif used to determine the temperature of the gases

  exhaust with a lambda probe whose temperature

ture is set.

  For this purpose, the invention relates to a method in which the lambda probe is set to a constant temperature and in that the temperature of the exhaust gas

  is determined from the electrical power supplied.

  The invention also relates to a device characterized in that there is a regulator for adjusting the temperature of the lambda probe to a value that can be predefined and an operating block that determines the temperature of the exhaust gas. from the electric power supplied to the heating element of the lambda probe

  where appropriate, at least one other parameter, which

  exhaust gas flow in the pipeline.

exhaust.

  According to other features of the invention

tion:

  - the temperature of the exhaust gas is de-

  terminated in the case of a determined flow of the exhaust gas from the electric power;

  - the temperature of the exhaust gas is de-

  terminated from the electric power and at least one parameter characterizing the flow of the exhaust gas;

  - the temperature of the exhaust gas is de-

  tected in the case of an internal combustion engine

  shot of electric power and speed of rotation; - in the case of an internal combustion engine in the intake side of which a throttle valve is located, the temperature of the exhaust gas is determined from the electric power, the speed of rotation and the angle of rotation of the throttle valve or the pressure in the intake pipe downstream of the throttle valve; - In the case of an internal combustion engine, the temperature of the exhaust gas is determined from the electrical power and the mass of the intake air or the flow rate of the intake air; - the power is continuously supplied

  electrical power and can be determined by measuring an inten-

  and a voltage where the electrical power is supplied cyclically and can be determined from the cycle time; the temperature of the exhaust gas is determined by means of a calculation rule or a

  characteristic curve or a characteristic field.

Advantages of the invention

  The invention has the advantage of allowing a

  the temperature of the exhaust gas

  a lambda probe whose temperature is, for example,

  set for reasons of measurement accuracy.

  In some advantageous configurations of the invention, the flow of the exhaust gases is taken into account.

  consideration in the case of determining the temperature

  of exhaust gases so that in almost

  that all the operating conditions of the device producing the exhaust gases it is possible to have

a reliable determination.

  The exhaust flow can be

  characterized by different operating parameters

  is lying; it then depends on the specific case of application to choose the operating parameter or the combination

  operating parameters to use. From this

  In this way, the invention can be used in a very flexible and

  In general, it is not necessary to have

  additional sensors, because the detectors can already be used

existing ones.

  The present invention will be described below in more detail with the aid of one embodiment.

shown in the accompanying drawing.

  Description of the embodiments

  On the block diagram of the single figure,

  represented an internal combustion engine 100. On the

  internal combustion engine 100, a pipe has been arranged

  exhaust gas 102, through which the exhaust gases emitted by the internal combustion engine are exhausted. In the exhaust pipe 102 is disposed a lambda probe 104, which can be heated at

  by means of an electric heating element 106.

  108 sets the lambda probe 104 on a constant temperature, the regulator 108 is connected to the lambda probe 104. By means of this connection, the regulator 108 determines

  the internal resistance Ri of the lambda probe which is func-

  of temperature and which serves as a real value for the

  regulator. In addition, the regulator 108 is connected to the heating element 106. By means of this connection the regulator 108 supplies the heating element 106 with an electric power P. in the case where the real value of the internal resistance Ri of the lambda probe 104 exceeds the set value stored in the regulator 108, that is to say in case the actual temperature of the lambda probe 104 is lower than the desired temperature. In addition, by this link the regulator 108 informs the operating block 110, what is the electrical power it provides to the heating element 106. Another input

  of the operating block 110 is connected to a video detector.

  rotational speed 112, which is arranged on the engine

  internal bustion 100 and detects the rotation speed n.

  The internal combustion engine 100 sucks

  an intake pipe 114 a mixture of air and fuel.

  In the suction pipe 114 are arranged, seen in the

  direction of the flow of the sucked air, a detector 116

  to detect the air flow q or the mass of air flowing m, a throttle valve 118, a pressure detector 120 for detecting the pressure in the inlet pipe and at least one injector 122 All of the compounds in this intake pipe and at least one injector 122 are optional, i.e., depending on the embodiment, only a portion of these components may be required. The detector 116 delivers a signal q. for the air flow or a signal m, for the air mass flowing, at the operating block 100, the flap

  throttling 118 delivers a signal a for the angle of rotation

  the throttle valve and the pressure sensor delivers a pS signal for the pressure in the inlet pipe. At its output the operating block 110 delivers

  a TAbg signal for the temperature of the exhaust gas.

  We will explain in the following how the operating block 110 determines the temperature of the gases

  exhaust from its input quantities.

  It is assumed that the temperature

  of the lambda probe 104 is larger than the temperature

  of the TAbg exhaust gas. It is then only possible to control the electric power P supplied to the heating element 106 so that the desired temperature of the lambda probe 104 is established.

  assumes that the desired temperature is con-

  aunt. Under these conditions, the electric power P, which is supplied to the heating element 106 to maintain the desired temperature of the lambda probe 104, depends on the intensity with which the lambda probe 104 is cooled by the exhaust gas in the heating pipe. Exhaust 102. If the lambda probe 104 is strongly cooled by the exhaust gas, it is necessary to have a high electrical power P. If the lambda probe 104, on the other hand, is only weakly cooled,

  only a small electrical power P is needed.

  The cooling action of the exhaust gas depends on the temperature of the exhaust gas TAbg and the flow of the exhaust gas. There is a functional relationship between the three variables: the heating power P, the exhaust gas temperature TAbg and the exhaust gas flow. If these two quantities are known, we can determine the third, for example at

  using a calculation rule or by means of a field characteris-

  empirically determined. With the process according to the invention, the temperature of the gases will be determined.

  exhaust TAbg. Different variants are foreseen.

  In a particularly simple embodiment, it is assumed that the flow of the exhaust gas is approximately constant or that the effects of fluctuations in the flow of the exhaust gas can be neglected. In this way, only the electrical power P is used to determine the temperature of the exhaust gas TAbg and can be done from there by means of a characteristic curve which is acceptable.

  for this exhaust gas flow approximately

  As. If the flow of the exhaust gas depends on the

  In principle, the same process can be used. However, it is good to ensure that the exhaust gas temperature TAbg is determined under the operating conditions for which the characteristic curve has been collected. In case one wishes to have a determination of the temperature of the gases

  TAbg exhaust in different operating conditions.

  several characteristic curves can be prepared.

  c. It is then necessary to choose the characteristic curve

  tick that is drawn for the operating conditions

correspondingly.

  If, on the other hand, the flow of exhaust gases

  is not constant, it is appropriate to choose for the corresponding application case appropriate parameters which characterize the flow of the exhaust gas. In the case of an internal combustion engine 100 without valve

  such as a diesel engine, such

  appropriate range is constituted by the rotation speed of the internal combustion engine 100, because there is an unequivocal relationship between the speed of rotation n and the flow of the

  exhaust gas. In this case of application, the temperature

  Exhaust gas TAbg is determined by means of a characteristic field, which is deployed with respect to the electric power P and the rotational speed n. The characteristic field can be determined for example from

empirically.

  In the case of a diesel-type internal combustion engine with a throttle valve 118 or a gasoline internal combustion engine with a throttle valve 118 the flow of the exhaust gas does not depend solely on the speed of rotation n but also

  the angle of rotation a of the throttle valve. In con-

  sequence, it is appropriate to use, in this case

  of application, a characteristic field for determining

  the temperature of the exhaust gas TAbg, which is

  established according to the electrical power P of the

  rotation speed n and the angle of rotation a of the throttle valve. Instead of the angle of rotation a of the throttle valve it is also possible to use the pressure pS in

  the inlet pipe downstream of the throttle valve 118.

  It is then necessary to use a characteristic field which is a function of the electric power P. of the speed of

  n rotation and pressure in the inlet pipe pS.

  When another load signal is available, which is related to the flow of the exhaust gas, it is also possible to use a characteristic field which is a function of the electrical power P of the speed of rotation n and of

  this charging signal. Such a charging signal is for example

  the time of the injection in the case of a combustion engine

internal combustion with gasoline.

  If the internal combustion engine, regardless of its type of construction, is equipped with a flow sensor for the intake air flow q or the air mass

  sucked m, it is not necessary to have a signal of vi-

  rotation speed. This exhaust gas temperature TAbg can be determined in this case from a characteristic field which is established as a function of the electrical power P and the flow rate or the mass of air sucked.

  When determining the electrical power

  Many different methods can be used. Yes

  the electrical power is supplied to the heating element

  cyclically, it can be determined from the cycle rate. If electric power P is supplied

  On a continuous basis, it is determined by means of a

  sure of intensity and tension. Depending on the application it may be wise to use not the instantaneous electric power P, but a mean electric power for the determination of the exhaust gas temperature TAbg.

  The method according to the invention for determining

  the temperature of the TAbg exhaust with

  lambda 104 can then still be used when

  laying of a lambda probe 104 whose temperature is regulated

  EEA. A typical application area is the use that

  has been described above in the case of a combustion engine

  internally. In addition, the invention can also be used

  in heating systems of any type. From the temperature of the exhaust gases of a heating installation, it can be determined by

example its performance.

R EV E ND I C AT ION

  1) Method for determining the exhaust gas temperature (TAbg) with an electrically heated lambda probe (104), characterized in that the lambda probe (104) is set to a constant temperature and that the temperature of the gases exhaust (TAbg) is determined from the electrical power supplied (P).

  2) Process according to claim 1, characterized

  in that the exhaust gas temperature (TAbg) is determined in the case of a determined flow of

  exhaust gas from the electric power (P).

  3) Method according to one of the preceding claims

  cedentes, characterized in that the temperature of the gases

  exhaust air (TAbg) is determined from the

  electrical power (P) and at least one characteristic parameter

  the flow of the exhaust gas.

  4) Method according to one of the preceding claims

  cedeentes, characterized in that the exhaust gas temperature (TAbg) is detected in the case of a combustion engine.

  internal combustion (100) from the electric power

  that (P) and the speed of rotation (n).

  Method according to one of claims 1 to

  3, characterized in that in the case of a combustion engine

  (100) in the intake side of which a throttle valve (118) is located, the temperature is determined

  exhaust gases (TAbg) from the electrical power

  scale (P), speed of rotation (n) and angle of rotation of the throttle valve (a) or pressure in the intake pipe (pS) downstream of the valve

throttling (118).

  6) Method according to one of claims 1 to

  3, characterized in that in the case of a combustion engine

  internal temperature (100) the exhaust gas temperature (TAbg) is determined from the electrical power (P) and the intake air mass (m) or

intake air (q).

  7) Method according to one of the preceding claims

  cedentes, characterized in that

  the electrical power (P) and can be determined by measuring an intensity and a voltage, or by supplying the electrical power cyclically, and

  can determine it from the cycle time.

  8) Method according to one of the preceding claims

  cedentes, characterized in that the temperature is determined

  of exhaust gases (TAbg) by means of a rule of

  calculation or a characteristic curve or characteristic field.

  teristic. 9) Device for determining the temperature of the exhaust gas (TAbg) with a lambda probe (104)

  electrically heated, characteristic device

  in that there is a regulator (108) for adjusting the temperature of the lambda probe to a predefined value and an operating block (110) which determines the temperature of the exhaust gas ( TAbg) from the electric power (P) supplied to the heating element (106) of the lambda probe (104) and, if appropriate, at least one other parameter, which characterizes the flow of gases

  exhaust system in the exhaust pipe (102).