阅读说明：本技术 用于诊断废气传感器的方法 (Method for diagnosing an exhaust gas sensor ) 是由 B·莱德曼 F·鲍曼 C·贝沃特 D·迪特默-戈贝利奇 于 2020-03-24 设计创作，主要内容包括：本发明涉及一种分析评价和控制单元,尤其构造为ASIC,用于运行具有至少一个电导线(201、202、203、204)的宽带λ探测器(200),其中,所述分析评价和控制单元(100)具有至少一个电接头(RE、IPN、APN、MES),用于与所述宽带λ探测器(200)的电导线(201、202、203、204)电连接,其特征在于：装置(131),用于确定流到所述电接头(RE、IPN、APN、MES)中的电流的应有值(Iq)并且用于将所述应有值(Iq)与实际流到所述电接头中的电流(Ip)进行比较；和比较器(130、130’),用于将施加在所述电接头上的电势(Up)与预给定的极限(L1、L2)进行比较。(The invention relates to an evaluation and control unit, in particular designed as an ASIC, for operating a broadband lambda probe (200) having at least one electrical line (201, 202, 203, 204), wherein the evaluation and control unit (100) has at least one electrical connection (RE, IPN, APN, MES) for electrically connecting to the electrical line (201, 202, 203, 204) of the broadband lambda probe (200), characterized in that: -means (131) for determining a due value (Iq) of the current flowing into said electric joint (RE, IPN, APN, MES) and for comparing said due value (Iq) with the current (Ip) actually flowing into said electric joint; and a comparator (130, 130') for comparing the potential (Up) applied to the electrical connection with a predefined limit (L1, L2).)

1. An evaluation and control unit, in particular designed as an ASIC, for operating a broadband lambda probe (200) having at least one electrical line (201, 202, 203, 204), wherein the evaluation and control unit (100) has at least one electrical connection (RE, IPN, APN, MES) for electrical connection to the electrical line (201, 202, 203, 204) of the broadband lambda probe (200), characterized in that:

-means (131) for determining a due value (Iq) of the current flowing into said electric joint (RE, IPN, APN, MES) and for comparing said due value (Iq) with the current (Ip) actually flowing into said electric joint; and

a comparator (130, 130') for comparing the potential (Up) applied to the electrical connection with a predefined limit (L1, L2).

2. Method for diagnosing at least one electrical line (201, 202, 203, 204) of a broadband lambda probe (200), wherein the electrical line (201, 202, 203, 204) of the broadband lambda probe (200) is connected to a junction (RE, IPN, APN, MES) of an evaluation and control unit (100), in particular according to claim 1, wherein the presence of a short circuit or shunt (300) of the electrical line (201, 202, 203, 204) is excluded just when the potential (Up) applied to the junction (RE, IPN, APN, MES) does not lie outside a predefined limit (L1, L2) and the current (Ip) flowing into the junction (RE, IPN, APN, MES) does not differ from the desired value (Iq, I' q) by more than a threshold value;

and/or

A short circuit or shunt (300) of the electrical line (201, 202, 203, 204) is deduced when at least one of the following conditions is fulfilled:

-the potential (Up) applied to the junction (RE, IPN, APN, MES) lies outside a predefined limit;

-the current (Ip) flowing into the junction (RE, IPN, APN, MES) differs from the due value (Iq, I' q) by more than a threshold value.

3. Method according to any one of the preceding method claims, characterized in that if the current (Ip) flowing into the junction (RE, IPN, APN, MES) differs from the due value (Iq, I' q) by more than a threshold value, further:

-if said current (Ip) is less than the supposed value (Iq, I' q), a short circuit or shunt to ground is deduced; and/or

-if said current (Ip) is greater than the supposed value (Iq, I' q), a short circuit or a shunt to the supply potential is deduced.

4. Method according to any of the preceding method claims, characterized in that if the potential (Up) applied on the joint (RE, IPN, APN, MES) lies outside a predefined limit (L1, L2):

-if the potential (Up) lies below a predefined limit (L1, L2), a short circuit or shunt (300) to ground is inferred; and/or

-if the potential (Up) lies above a predefined limit (L1, L2), a short circuit or shunt (300) to the supply potential or the battery voltage is concluded.

5. Method according to any one of the preceding method claims, characterized in that the due value (Iq, I' q) is given by a current value (Iq) which is specific for a constant current source (110) of the control and evaluation unit (100) which is connected to the connection (RE, IPN, APN, MES).

6. Method according to any of the preceding method claims, characterized in that the threshold value is given by an expected measurement accuracy.

7. Method according to one of the preceding method claims, characterized in that the broadband lambda probe (200) has a plurality of electrical lines (201, 202, 203, 204) and the evaluation and control unit (100) has a plurality of connections (RE, IPN, APN, MES), wherein each line (201, 202, 203, 204) is connected to a respective connection (RE, IPN, APN, MES), wherein the diagnosis is carried out periodically for all lines (201, 202, 203, 204).

Background

For example, DE19729696 a1 discloses the possibility of diagnosing a lambda probe, wherein a method for checking the function of a lambda probe is proposed, in which the internal resistance of the probe ceramic is measured, compared with a desired value determined as a function of the temperature of the gas to be detected and the heating output of the probe heater, and a fault signal is generated if the measured value exceeds the desired value.

Disclosure of Invention

The object of the invention is to be able to always reliably diagnose the presence of a short circuit or shunt of an electrical line of a broadband lambda probe. This is achieved by the features of the independent claims.

In particular, it is provided that the short circuit or shunt can be determined by the potential applied to the terminal being outside a predetermined limit. This can be, for example, a limit which is given by the potential which is no longer exactly predictable in the normal operation of the broadband λ probe, i.e. when no short circuit is present.

The comparison of the potential applied to the terminals with the predefined limit can preferably be carried out using a hardware comparator, since the hardware comparator operates very rapidly, so that damage to the broadband lambda probe and/or to the evaluation and control unit, which would otherwise be feared in the event of such a fault, can be reliably avoided.

In addition, the invention provides in particular that a short circuit or a shunt is also determined if the current actually flowing into the connection differs from the desired value by more than a threshold value. This is also possible in principle, without the potential applied to the connection lying outside the specified limits, i.e. without a short circuit having been detected according to the above-described solution. Thus, all short circuits and shunts can be identified with the method according to the invention.

In this case, depending on whether the current flowing into the connector is greater or less than the due value, it can be inferred whether the short circuit to the ground or the positive potential occurs.

In particular, it is possible that the value to be given by the current value is specific to the constant current source of the control and evaluation unit connected to the connection. The connection between the terminal and the constant current source can be realized, for example, by an electrochemical unit of the broadband lambda probe, which is connected to the terminal and to a further terminal of the signal and evaluation unit via two electrical lines of the broadband lambda probe.

If the wiring of the broadband lambda probe is more complicated than in the case described above, the desired value is determined on the basis of further predetermined information and/or on the basis of measurements and/or on the basis of calculations.

There should be a current value that may not be equal to zero. On the other hand, a value of 0 μ a may also be allowed.

It is possible in particular for the threshold value to be given by a desired measurement accuracy, for example a measurement accuracy of 2 μ a or less.

It is possible for the broadband lambda probe to have a plurality of electrical lines and for the evaluation and control unit to have a plurality of connections, each of which is connected to a respective connection. The diagnosis can then be carried out periodically for all the lines, that is to say in particular repeatedly in a defined sequence. Further processing of this information can be used to find the short circuit voltage and the short circuit resistance Rk, and the presence of a short circuit (Rk <1 ohm) can be selectively distinguished from the presence of a shunt circuit (1 megaohm > Rk >1 ohm) for the wire.

A fault-free situation is considered in particular if the resistor, which is in the form of a short-circuit resistor, has a resistance value of more than 1 megohm, i.e. there is neither a short circuit nor a shunt at this electrical connection of the broadband lambda probe; the electrical connection is intact.

Drawings

Figure 1 shows a broadband lambda probe and an evaluation and control unit connected thereto,

figure 2 shows a flow chart of an embodiment of the method according to the invention,

fig. 3 illustrates the components of fig. 1 in the event of a fault.

Detailed Description

Fig. 1 shows an evaluation and control unit 100, which is connected via its four electrical connections RE, IPE, APE, MES to four electrical lines 201 and 204 of a broadband λ detector 200. Electrical lines 201 and 204 of broadband lambda probe 200 lead in this example to the electrodes of electrochemical nernst cell 210 and electrochemical pump cell 211 of broadband lambda probe 200 and to ohmic resistor 220 of broadband lambda probe 200.

The details of the broadband lambda probe can be implemented, for example, as described in DE 102011007068 a 1.

In this example, the evaluation and control unit 100 has a constant current source 110, which can be connected to the connections RE, IPE, APE, MES of the evaluation and control unit 100 via corresponding switches (not shown), and has a current measuring device 120, which can likewise be connected to the connections RE, IPE, APE, MES of the evaluation and control unit 100 via further switches (not shown).

In this example, after the electronic device has been started, the potential Up at the connection IPE of the evaluation and control unit is first measured (method step S1, see fig. 2).

Then, in this example, it is determined by means of the hardware comparator 130, 130' that the potential Up lies within the predefined limit L1, L2 (method step S2).

After a sufficiently low resistance of the electrochemical unit has been ensured by passive and/or active heating of the broadband λ probe, the constant current source 110 of the evaluation and control unit 100 is connected to the connection APE and the current measuring device 120 of the evaluation and control unit 100 is connected to the connection IPE (method step S3).

The value Ip measured by the current measuring device 120 is compared with the value Iq specific to the constant current source 110, for example by means of the software of the evaluation and control unit 100 (method step S4). In this example, the value Iq is a value stored in the means 131 for determining that a value should be present.

In this example, these values Ip, Iq match. Overall, it is therefore assumed that neither a short circuit nor a shunt is present on the line of the broadband λ -probe 200 connected to the connection IPE (method step S5).

Conversely, the method may conclude that a short circuit or a shunt is present, either when the potential Up lies outside a predefined limit, or when the value Ip measured with the current measuring device 120 differs from the value Iq specific to the constant current source 110 by more than a threshold value. In this case, the corresponding fault is recorded, for example, in a fault memory of the evaluation and control unit or in a fault memory of a control unit connected to the evaluation and control unit (method step S6).

Fig. 3 illustrates the components in fig. 1 in the event of a fault, in which a short circuit 300 occurs between the line 202 of the broadband lambda probe and, for example, the battery voltage. In this case, an additional current flows to the current measuring device 120. The value Ip measured with the current measuring device 120 then differs from the Iq specific for the constant current source 110 by more than a threshold value, although in this example the potential Up is still within the predefined limits L1, L2.

An alternative embodiment of this example provides that, for comparison with Ip, the value Iq specific for the constant current source 110 is not used, but rather the constant current source 110 is connected in a separate method step within the evaluation and control unit to the current measuring device 120, so that the actual value Iq' of the constant current source 110 is measured by the current measuring device 120. This measured actual value Iq' is then used instead of the specific value Iq for comparison with Ip as described above.