JPH07502317A - Method and apparatus for operating an electrically heatable catalytic converter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Method and apparatus for operating an electrically heatable catalytic converter The present invention provides an electrically heatable catalytic converter, whereby the converter and/or maintained above the minimum temperature required for conversion.

The invention also relates to a corresponding device. Electrically heatable catalytic converter , especially used in automobiles to meet particularly stringent exhaust gas regulations. General , they are placed upstream of the main converter.

In an internal combustion engine, the operation during the starting phase, that is, before the engine reaches its operating temperature. Particularly large amounts of contaminants are produced in the first 2.3 minutes of the process. At this stage, the result These pollutants are not sufficiently converted by the catalytic converter because these This is because the converters have not yet reached their operating temperature.

To improve this, WO39/10470 and WO39/10471 Discloses electrically heatable converters and methods for operating them . Such converters facilitate catalytic reactions in relatively short periods of time and at relatively high currents. The contamination generated during the cold start-up phase as a result of being heated to the temperature required for A significant portion of things can be transformed. The heatable converter is They may be heated to their operating temperature either before starting or shortly after they are started.

It is also known to combine these options.

High energy consumption of electrically heatable converters, and heating them quickly Due to the current strength required to electric power consumers, which are electronically controlled and electrically controlled using special means. It is necessary to operate the switch automatically. Two conflicting interests must be considered. No. On the one hand, in order to meet emissions regulations, every time the engine is started , the electrically heatable catalytic converter is guaranteed to do its job reliably. On the other hand, the availability of the vehicle must be affected by this composition. However, if there is a malfunction in the heatable converter, additional precautions should be taken. This is conceivable if no measures are taken.

Vehicle fire safety must of course also be ensured, with exhaust purification systems Damage to the stem itself should also be reliably avoided.

The object of the invention is to provide a method and method for operating an electrically heatable catalytic converter. and corresponding equipment, where the maximum operating speed of the converter itself is -fty is achieved without compromising the availability of the vehicle.

To this end, as part of the exhaust gas cleaning system, electronic engine Electrically heatable catalytic converter located downstream of the internal combustion engine with control A method is provided for operating the catalytic converter, whereby the catalytic converter is Current is applied through the control and power switches and its temperature is the minimum required for catalytic conversion. Raised to and/or maintained at a marginal temperature. This method is It has the following characteristics.

a) The temperature of the converter is a controlled variable of at least two different control circuits. It is.

b) In the normal state, regulation is provided by at least one priority control circuit.

C) Each control circuit during operation is automatically monitored to check for malfunctions.

d) If a malfunction is detected, a switch to a different control circuit is made automatically.

The details of the invention are explained by means of exemplary embodiments and drawings. converter's Regulation of temperature does not depend solely on the functionality of a single control circuit with various elements. In fact, if the preferred control circuit intended for regulation If it is found that the The principle is found in the fact that there is a path. For example, under normal conditions, Regulated by a preferred control circuit, where the actual value transducer is the temperature sensor of the converter. If this happens, the temperature sensor may malfunction. If additional precautions are taken If not, in which case the converter is fully (unheated or both of which would be undesirable and even dangerous in the second case. . However, according to the present invention, malfunction of the control circuit can be confirmed. The operation can be stopped and replaced with a different control circuit. The second control circuit is For example, you can use a calculated temperature as an actual value, which can be obtained from a measuring sensor or or data available from the engine control unit. the simplest In certain cases, conditioning is made by heating for a predeterminable period of time. obtain. This type of adjustment can also be referred to as control, but in this specification it is simply referred to as control. Therefore, there is no distinction between adjustment and control.

How many different control circuits and which circuits are provided on the electronic components? This means operational safety and availability of electrical heating of catalytic converters. According to the requirements applicable for. Electronic configuration to avoid relying on a single control circuit The element may include at least two control circuits, such as:

a) Control circuit with a temperature sensor as actual value converter in the catalytic converter.

b) The actual value is calculated by heat balance from the data of the engine control unit. control circuit.

C) The actual value is confirmed from the value measured from the temperature measurement sensor outside the catalytic converter. control circuit.

d) calculations, e.g. from ambient temperature sensors and/or engine temperature sensors; Determine the temperature of the catalytic converter by determining the heating time as a function of the Raise, control circuit. e) Catalytic converter by specifying a certain heating time A control circuit that increases the temperature of the tank.

All of these control circuits have the following elements in common. controlled system catalytic converter as a system, a power switch as a final control element, and a with the temperature of the catalytic converter as a control variable. From some particular points of view, We next focus specifically on the control loop according to b), which includes a temperature sensor is not present in the catalytic converter or it is damaged, Because it is especially important. Primarily, modern electronically controlled engines In engine control, a large amount of data about the operating status of the engine resides in the engine control system. how much fuel and air is reaching the engine at that time. How much is burned, and how much exhaust gas is emitted from the engine? temperature, and how much convertible components are still present in the exhaust gas. It can be derived with great precision whether there is a residual energy content of Ru. The well-known heating capacity of the catalytic converter also from the power drain during electrical heating and information, the temperature will be determined very accurately. Exhaust gas temperature Tex h['C] can be initially determined using an experimentally determined approximate formula as follows.

Texh=m・(log (t+2) 3) l' In the above formula, m = mass flow rate of gas [kg/s A=system defined constant, e.g. 3B=system defined constant , for example 1.15t = time after engine start [8] If the gas mass flow rate m is not available from the engine control, it is calculated as You may be

In the above formula, HV=engine stroke volume [m3] n=engine speed [1/s] 9G as = 1. 2 [k g/m3] Psuct = suction pressure [bar ] Pamb = ambient pressure [bar] = 1 [bar] to heat the exhaust gas to operating temperature The required amount of energy QGas for can be done.

QGa! z+++ = (Texh-Ts tart) mm0cex h II QG a S (I+-11 in the above formula n = exponent of calculation (e.g. second clock) Tst・art = catalyst in converter Temperature at which reaction starts [°C] Cexh = heat capacity of exhaust gas = 1000 [J/kgK ]Energy Qca required to heat the catalytic converter to temperature Tstart The amount of t is as follows.

Qcat=Qel-te-CHK-Tstart In the above formula Qe l=supplied heating power [W] te = time from start of heating CHK = Heat capacity of catalytic converter [J/K] Electrical heating power is derived according to the following It may be calculated as follows.

U = battery voltage [V] RHK = Electrical resistance of converter [Ω] The total amount of energy Qtot is calculated using the following heat balance meter using the above calculated value. May be derived by calculation.

QjOjtn+ =QgaS+-+ +Qca t+Qe l+n+if QtO If ttn+ is negative, the actual temperature of the catalytic converter is lower than Tstart. further heating is required. If Qtot,. , if is positive, the catalyst change Conversion will begin and heating will cease.

Considering that the ignition temperature of the catalytic reaction is higher due to the aging of the catalyst, the catalyst The set value of the converter temperature and the calculated Tstart are determined by the aging of the catalytic converter. may be set higher depending on time. Constants A and B are automobile specific conditions, such as the distance of the catalytic converter from the engine and the exhaust gas system. The layout of the stem must be adapted empirically.

or at a clock speed of 1 second, sufficient to give sufficiently accurate actual values for adjustment. or faster, the calculation is made and the actual value ascertained is within the sensing range. It will be monitored again to see if the If the calculated "actual value" is outside the range If so, the regulation loop is defective and switching to another regulation loop is required. .

In any case, if you have two or more control circuits anyway, you can run them simultaneously. to allow cross-comparison and/or cross-monitoring for malfunctions. That makes sense. In this case, if turn-on is not done by another control circuit, If not, this control circuit turns on the current and if it is turned on by another control circuit. , if turn-off does not occur according to predetermined criteria, this circuit will This control circuit has the simplest configuration and is least likely to cause malfunctions. Reliable functionality is guaranteed. A predetermined time period for the simplest control circuit Turn the current on at intervals and turn it off again after a predetermined time interval. Ru. It makes sense to choose pure timing control means. This time interval It may also be determined by some value such as ambient temperature, engine temperature, or other criteria. Ru.

If some predetermined conditions are met, e.g. If the energy is below the minimum required to start the engine, then or if the voltage drop across the power switch is unacceptable for the car. , all control circuits and therefore electrically heatable catalytic converters are also It is necessary that the operation be stopped under certain preconditions. Descend via power switch It is particularly useful to measure the voltage at which Full as long as the power switch is open Battery voltage can be applied to it and checked. If the power switch is closed If installed, the voltage drop across this switch will be very low as long as the system functions correctly. small. If there is a larger voltage drop, the catalytic converter is shorted Or the power switch is defective and has excessively high resistance. these conditions Both conditions will cause the heating system to shut off. If the power switch If the voltage does not drop when closed, the heating current circuit must have been interrupted. do not have. Measuring the voltage drop across the power switch determines the functional capability of the system. This is a fairly flexible method for monitoring.

Malfunctions of the catalytic converter heating system are always indicated as error warnings. or stored in memory. In many cases, possible errors Diagnosis or definition could already be achieved thereby. Legal requirements of various countries Depending on the case, such error warnings may also be used to prompt the driver to activate a repair device. , may require restrictions on driving movements.

Current loops, current sources, power switches, power supplies for power from about 0.5 to 10 kW electrically heatable converter and electrical connection line. Using an assembly with the following features to operate a capable catalytic converter: This objective is further solved.

a) The power switch is a common control member and the catalytic converter is at least A common regulation path of two different regulation loops, the common controlled value of which is , is the temperature of the catalytic converter.

b) The control electronics located within the electronic component module Associated with a regulating loop.

C) Electronic components provide a control loop for testing and a functional control loop. Contains means for selecting.

Electronic components may be integrated within the vehicle's engine control or may be separate may be placed in In general, at least power switches are protected against electromagnetic interference. They are placed separately for safety.

The first control circuit preferably includes a temperature sensor as a real value converter in the catalytic converter. , which is connected to electronic components. from the engine control unit By selectively processing data and other measurements, the catalytic converter The actual value converter, which calculates the actual value of the temperature of the controller, belongs to the second control circuit. finally simple Timing control means that are specific or dependent on measured values are subject to further control. It exists as a control circuit.

An exemplary embodiment of the invention is schematically shown in the drawing.

Figure 1 shows the arrangement of an electrically heatable catalytic converter and other components of a motor vehicle. FIG.

Figure 2 shows the electrical and electronic system that is part of the electrically heatable catalyst. FIG. 3 is a diagram showing a schematic layout.

FIG. 3 is a diagram showing a schematic layout of electrical components with multiple control circuits. be.

FIG. 4 shows how to safely operate an electrically heatable catalytic converter according to the present invention. FIG. 2 is an example simplified flowchart diagram for a flow of a method for performing a process;

Figure 1 shows an electrically heatable catalytic converter located under the floor and following the internal combustion engine 3. FIG. The engine 3 has a control line and a measurement line 4 2 to the engine control unit 4. The electronic component 5 also has a measuring line 41 to the engine control unit 4.

As shown schematically, an engine control unit 4 and electronic components 5 can also be combined into one unit. The car has battery 6 and the driver's seat. Various sensors located 7.8.9.10.11, safety safety lever, ignition lock It also includes a door, a door and/or a door/handle. outside temperature or temperature A temperature sensor 12 may also be present to measure engine temperature. up to several hundred amperes A power switch 20 suitable for switching high currents is typically a battery placed near the battery.

As shown in FIG. 2, the actual heating current circuit includes a battery 6, a heating current line 61, Power switch 20, heating current line 21, catalytic converter 2, grounding line 22 and connection A ground wire 62 is included. In principle, the catalytic converter should only be applied after engine 3 has started. If heat is generated, it can be used as an energy source instead of a generator or battery 6. It's okay.

The power switch 20 is activated as required by the electronic component 5 via a control line 27. Triggered when The voltage drop across the power switch 20 is measured with a voltmeter 25 and the result of the measurement can be communicated to the electronic component 5 via the measurement line 26. electronic The target component 5 is connected to the engine control unit 4 via a measuring line 41 and thus Data is passed from the engine control unit 4 to the electronic components 5 and vice versa. is also possible.

The electronic component 5 also connects a temperature sensor 2 of the catalytic converter 2 via a measuring line 24. This also applies to 3. Selectively present sensors 7.8.9.10.11 and selective temperature The readings of the degree sensor 12 may also be connected to electronic components.

FIG. 3 shows, fairly schematically, one example of the basic layout of the electronic component 5. . This component consists of three or more sets of control circuit electronics 52.53.54 including. Using the temperature measurement of the temperature sensor 23 as the actual value, the control circuit electronics Nix 52 serves to regulate the temperature of catalytic converter 2. control circuit elect Ronics 54 uses actual values ascertained from heat balance calculations. This total The calculations are made with data from the engine control unit provided via line 41. . The control circuit electronics 53 includes a heating circuit for heating the catalytic converter. Includes timing control means to selectively take external measurements into account when calculating intervals . The monitoring electronics 51 monitors the functional capabilities of the control circuit and if If a defect is detected in the control circuit, the non-functioning control circuit can be switched to a functioning control circuit. Make a change. The monitoring electronics 51 may also contain other information, such as a power switch. Information about the voltage drop across switch 20 can be taken into account and should an abnormal situation occur. This allows you to interrupt the heating or not start it in the first place. .

A highly simplified flow for operating an electrically heatable catalytic converter A diagram is shown in FIG. A heated catalytic converter is usually It has to be taken into account that it is associated with a number of features that have been omitted in order to do not have. In particular, in many types of vehicles, secondary air is supplied to the exhaust gas system. The supply can be regulated by the temperature of the heated catalytic converter and other parameters. further measures should be taken regarding its functionality and its operating conditions. electronics to monitor the catalytic converter. child These parts have been omitted from this overview. Responds to triggers from various sensors in the car The catalytic converter may be When heating of the motor is requested by the engine control, the following sequence occurs.

First, it is checked whether the voltage across the power switch is at the threshold Ru. If it is not high enough, an error report will be issued and the heating process will not start. . In this case, there is a malfunction in the battery 6 or the heating wire 21.22.61 or There may be a disconnection at 62. If the voltage is high enough, then the temperature sensor 23 The actual value is the issue. If it is within the permissible range, i.e. if it is perceivable If a reasonable temperature is reported, the catalytic converter (i.e., heater) is turned on. be done. A heating time measurement is triggered at the same time. Next, turn on the power via the power switch 2o. The voltage at which this occurs is once again an issue. In this respect, if it is not small enough , heater 2 is turned off and an error report is issued.

The power switch 20 may be partially defective or there may be a short circuit in the heater 2. Ru.

If the voltage across the power switch 2o is small enough, the temperature sensor 23 The actual value is again questioned and compared with the set value. If the actual value is less than the set value, The question is whether the maximum heating time has not been reached. If so, the temperature , starting from checking the actual value of sensor 23, the whole process is repeated. Finally, warm If the actual value of the temperature sensor 23 is no longer below the set value, the heater 2 is turned on. will be removed. In that case, the system has worked correctly.

If heater 2 is not turned off in this manner, it will exceed the maximum heating time. It is turned off at the end, but if the temperature sensor 23 is defective or all heating power This will result in an error report as the force may be too small.

If the actual value of the temperature sensor 23 during the start test is not within the tolerance range, this means that the temperature Indicates an error or short circuit in the sensor 23 or its measuring line 24. such a place If so, an error message is displayed and control is switched to another control circuit 54.

The control circuit 54 uses the value calculated from the engine control data as the actual value. . The value is also tested to see if it is within an acceptable range. like this , if heater 2 is not already turned on, it turns on. be done. The heating time measurement is turned on or likewise continued. This control In the circuit, the voltage across the power switch 20 is similarly tested and the maximum heating time A possible excess of is ascertained. When the control circuit 54 operates regularly, the engine The actual value calculated from the input data will be higher than the set value, and heater 2 will be turned off. Ru. This system can be used if there are no temperature sensor error reports.

Testing the actual value calculated from the engine data will confirm that this is outside the acceptable range. If it is found that Can be switched to 3. The circuit is tested to see if the maximum heating time has been exceeded If necessary, turn on heater 2, assuming heater 2 is not already on. Switch on. The heating time period is turned on again or continued. pa After testing the voltage through the power switch 20, the heating time is questioned and the maximum heating When the time is exceeded, the heater 2 is turned off. In this case, the system can still be used. However, there are two methods for calculating actual values from temperature sensor and engine control data. There is an error report.

As can be clearly seen, the control circuits are arranged hierarchically, i.e. the most The preferred control circuit is one that is accurate, but most susceptible to errors.

Only when it is partially unavailable, control is shifted to the next control circuit and the same This can be repeated by switching to a third circuit during breakdown. Ru. In principle, it is also possible to provide four or more circuits. If two temperature sensors The first control circuit may be duplicated if a Improves availability and allows mutual control between control circuits.

The lowest level in the hierarchy is a control system that is as free from errors as possible. It is important that in the simplest case it is pure timing control, Then, even if optimal control is not given, the availability of electric heating is remains high.

This method according to the invention of an electrically heatable catalytic converter To improve the operational reliability and availability of electrical heating without compromising performance. Ru. Maintain strict emissions regulations even if individual components of the control system malfunction , it is possible to comply with it with a high degree of confidence.

IG 3 international search report 1m++++~*1sA1+m+□, -PCT/EP92/Goyu88

Claims (13)

[Claims] 1. Internal engine control (4) as part of the exhaust gas purification system. located downstream of the combustion engine, whereby the catalytic converter (2) A current (I) is applied through the circuit (5) and the power switch (20) and the catalyst heated to or maintained above the minimum temperature required for conversion. 1. A method of operating an electrically heatable catalytic converter (2) comprising a) The temperature of the medium converter (2) is controlled by at least two different control circuits. b) control by at least one preferred control circuit in normal operation; It is done; c) each of the regulating control circuits is automatically monitored for malfunctions; d) that control is automatically transferred to another control circuit if a malfunction is detected; Characterized method. 2. characterized in that the control circuit has a different structure and/or a different complexity 2. The method according to claim 1. 3. If a malfunction is detected, an error indication will be issued or an error report will be recorded. 3. A method according to claim 1 or 2, characterized in that said information is stored. 4. A preferred control circuit is implemented in the form of a temperature sensor (23) of the catalytic converter (2). a value converter and the current (I) is a function of the temperature measured by the temperature sensor (23); according to claim 1, characterized in that it is provided in the catalytic converter (2) as Method. 5. The temperature of the catalytic converter (2) is controlled mutually. The system has a power switch (20) as a control element and a catalyst controller. Few of the following control circuits are such that the temperature of the converter is a controlled parameter. A method characterized in that at least two controlled parameters The circuit includes: a) a temperature sensor (23) as an actual value converter in the catalytic converter (2); a control circuit comprising; b) The actual value is calculated by heat balance calculation from the data of the engine control unit (4). c) measurement of the temperature transducer (12) outside the catalytic converter (2); a control circuit that allows the actual value to be verified from the fixed value, d) an external temperature sensor (12) and/or or by determining the heating time period depending on engine temperature sensor readings. a control circuit for increasing the temperature of the catalytic converter (2), and e) a control circuit which increases the temperature of the catalytic converter (2) during a fixed heating time period; A method according to one of the preceding claims. 6. Two or more control circuits operate simultaneously to compare each other and/or eliminate each other's errors. - enables monitoring and thereby allows for the simplest configuration and the most error-prone Reliable functionality is tied to fewer control circuits, and other control circuits are not switched on. This control circuit turns on the current when the to turn off the current when no other control circuitry switches it off. Method according to one of the preceding claims, characterized in that: 7. One of the control circuits, the simplest control circuit, is pure time control, Turn on the current for a predetermined time and turn on the current after the predetermined time Method according to one of the preceding claims, characterized in that turning off the . 8. When certain predetermined conditions are met, e.g. the available voltage or When the energy falls below the minimum value or the voltage drop across the power switch (20) When below the minimum value or above the maximum value, all of the control circuits and the catalytic converter Of the preceding claims, characterized in that the electrical heating of the heater (2) is deactivated. The method described in one of the above. 9. Switching off the electrical heating will trigger an error report and/or Characterized by allowing only limited driving movements to enter the nonce garage 9. The method according to claim 8. 10. Electrical with an electrical circuit for providing approximately 0.5 to 10 kW of power A device for operating a catalytic converter (2) that can be heated to , current (6), power switch (20), electrically heatable catalytic converter ( 2) and electric wires (21, 22, 61, 62), a) the power switch (20) is connected to a common final control of at least two different control circuits; The catalytic converter (2) is a common controlled system; the controlled parameter is the temperature of the catalytic converter (2); b) the various control circuits; The circuit has associated control electronics (52) arranged on the electronic component (5). , 53, 54), which is c) Selecting a functioning control circuit for monitoring the control circuits (52, 53, 54); The device is characterized in that the electronic component (5) comprises means (51) for selecting the Place. 11. The temperature sensor (23) of the catalytic converter (2) serves as the first control as an actual value converter. the sensor belongs to the control circuit and is connected (24) to the electronic component (5). 11. The apparatus of claim 10. 12. The actual value converter belongs to the second control circuit, and the converter is used for heat balance calculation. The claim is characterized in that the actual value is calculated from engine control data by 12. The device according to item 10 or 11. 13. Increasing the temperature of the catalytic converter (2) by time control of the current (53) According to one of the preceding claims, characterized in that an additional control circuit is present. Device.