DE10129126B4 - Method and device for influencing the operating temperature of a catalyst - Google Patents

Abstract

Method for influencing the operating temperature of a catalytic converter (24), in particular for rapid heating of the catalytic converter (24) of a motor vehicle with an internal combustion engine (14) with an automatic transmission (10), the operating temperature of the catalytic converter (24) being varied by varying the power loss of the automatic transmission ( 10) is influenced, characterized in that the automatic transmission (10) is a CVT transmission (10) which has a belt part (12) serving for power transmission, and that in order to vary the power loss of the automatic transmission (10) the voltage of the belt part ( 12) is changed.

Description

The present invention relates to a method for influencing the operating temperature of a catalytic converter, in particular for rapid heating of the catalytic converter, of a motor vehicle having an internal combustion engine with an automatic transmission. The invention further relates to a device for controlling and / or regulating the operating temperature of a catalytic converter, in particular for rapid heating of the catalytic converter, of a motor vehicle having an internal combustion engine with an automatic transmission.

State of the art

To reduce the resulting in motor combustion pollutants carbon monoxide, hydrocarbons and nitrogen oxides, a catalytic afterburning is required. This catalytic afterburning is carried out by catalytic converters (hereinafter referred to briefly as catalysts), which are provided in the exhaust systems of internal combustion engines. A catalyst causes a chemical process without significantly changing itself. For example, a catalyst may consist of a honeycomb carrier made of high temperature resistant magnesium aluminum silicate in cylindrical form. The honeycomb surfaces are usually coated with the precious metals platinum, palladium or rhodium. The best solution for exhaust gas purification is the selective or three-way catalytic converter, which reduces the toxic exhaust gases carbon monoxide, hydrocarbons and nitrogen oxides into carbon dioxide, water vapor and nitrogen. Compliance with the stoichiometric air-fuel ratio lambda = 1 is critical in this type of catalyst, which can be achieved by providing a lambda probe. The required for the lambda control accuracy of the mixture composition is achieved by a closed loop, in which constantly measured the exhaust gas and the supplied amount of fuel is corrected according to this measurement result. The sensor used is the lambda probe, which provides a voltage jump with a stoichiometric mixture (lambda = 1) and thus a statement as to whether the mixture is richer or leaner than lambda = 1. The lambda probe usually has a ceramic body, of which a part is in the exhaust gas flow, while the other part of the ceramic body is in communication with the outside air. The surfaces of the ceramic body (for example zirconium dioxide) are provided with electrodes made of a gas-permeable thin platinum layer. The used lambda probe ceramic material becomes conductive at temperatures above about 300 ° C for oxygen ions. If the oxygen content on both sides of the probe varies in size, an electrical voltage arises between the two boundary surfaces due to the particular properties of the material used. This voltage is a measure of the difference in oxygen content on both sides of the probe. In the exhaust gas of the internal combustion engine even with burns with excess fuel still residual oxygen components are present. The residual oxygen content is highly dependent on the composition of the air-fuel mixture supplied to the engine for combustion. This dependence makes it possible to use the oxygen content in the exhaust gas as a measure of the air ratio (lambda). In general, the probe ceramic is heated by the exhaust gas. For proper operation, as mentioned, relatively high temperatures are required, for example 300 ° C or more.

To bring the operating temperature of the catalyst quickly to the required working temperature, it is already known to use probes whose ceramic can be heated by an internal heating element.

Furthermore, it is known to influence the operating temperature of the catalytic converter by causing an efficiency deterioration of the internal combustion engine by performing a retardation of the ignition angle. In this way, the exhaust gas temperature is increased. An indirect increase in the air flow can be done by opening the throttle to compensate for the lower torque.

It is also already known to increase the engine idle speed to affect the operating temperature of the catalyst. Also in this way the air flow is increased. Despite the increase in the air flow and thus the raw emissions, the known measures in total lead to a significant emission reduction, since the catalyst starts much faster and then converts almost 100% of the pollutants.

The method and the device according to the invention are provided in connection with motor vehicles which have an automatic transmission. Without being limited thereto, such an automatic transmission may in particular be a CVT transmission. CVT transmissions are Continuously Variable Transmission (CVT). CVT transmissions include in Essentially two bevel gear and an example designed as a push belt band wrap. In this case, one of the bevel gear pair is connected to a drive, in particular an internal combustion engine, while the other bevel gear pair is connected to an output. To set the ratio of the CVT transmission and the tension of the belt part consist of the drive bevel gear pair and the Abtriebskegelradpaar generally from an axially fixed and an axially movable bevel gear. The drive bevel gear pair is also referred to as a drive pulley or primary pulley; The driven bevel gear pair is also referred to as a driven pulley or secondary pulley. The contact pressure of the axially movable bevel gears against the loop part is generally carried out by establishing a hydraulic pressure, for example by a pump. By a suitable choice of contact pressures, the desired ratio of the CVT transmission and the required tension of the belt part can be adjusted. For example, a torque converter and a planetary gear set with clutches for forward and reverse travel can be present for the transmission of power from the internal combustion engine to the drive bevel gear pair.

However, the known methods for influencing the operating temperature have some disadvantages. For example, excessive retardation of the ignition retard the ride and, in some circumstances, can lead to misfiring. High idle speeds are uncomfortable and annoying for the driver, which is why the idle speed is currently not usually increased above 1100 rpm. Furthermore, any increase in the idle speed of automatic transmissions leads to increased creep, that is, the vehicle accelerates when inserting "Drive" too strong. From the German patent application DE 199 34 756 A1 In addition, an apparatus and a method for controlling the transmission ratio of automatic transmissions are known in which is selected from different transmission ratio change characteristics to influence the operating temperature of a catalyst. The different ratios lead to different friction losses in the transmission, whereby the power loss of the transmission is affected. The operating temperature of the catalyst is thus influenced by varying the power loss of the automatic transmission. This is based on the finding that the power loss of the automatic transmission affects the air flow rate through the internal combustion engine and thus the operating temperature of the catalytic converter. This solution results in a lower increase in fuel consumption compared to a pure speed increase, since the power loss can be used directly to heat the automatic transmission. As a result, part of the initial losses can be recovered through consumption benefits over a full test cycle.

The variation of the power loss of the automatic transmission is thus effected by a variation of the friction losses of the automatic transmission. As a result, a fine metering of the power loss is given. Furthermore, the power loss can be varied in this way in a wide range.

From the European patent application EP 1 070 868 A2 In addition, a CVT transmission is known, in which the power transmission takes place through a looped part, which is wound around two bevel gear pairs, wherein for adjusting the gear ratio in each case a bevel gear of the bevel gear pairs is axially displaced.

Advantages of the invention

The inventive method is based on the generic state of the art in that the automatic transmission is a CVT transmission, which has a belt for serving transmission part, and that for varying the power loss of the automatic transmission, the tension of the belt part is changed. It is considered to be particularly advantageous if the method according to the invention provides that the variation of the power loss of the automatic transmission is additionally effected by a variation of the hydraulic losses of the automatic transmission. The wrap-around part may be formed, for example, by an initially mentioned push-pull belt. The contact pressure or the tension of the belt part can be adjusted independently of the vehicle speed or the engine speed.

In this context, the method according to the invention preferably further provides that the tension of the belt part is increased in order to increase the power loss of the automatic transmission. An increase in the tension of the belt part and thus of the contact pressure is not disadvantageous, for example, for a belt part in the form of a push belt, if the maximum additional pressure is not exceeded. The maximum additional pressure can be, for example, 30 to 50 bar, with low overdrive.

Similarly, the method according to the invention preferably further provides that the tension of the belt part is reduced in order to reduce the power loss. A reduction of the power loss leads to a reduction of the air flow rate through the internal combustion engine and thus to a slower heating of the catalyst or to a cooling of the catalyst. Even when reducing the tension of the belt part, a predetermined minimum value should not be undershot in order to avoid spinning or slippage of the belt part, for example between two bevel gear pairs. Turning the belt around may cause damage to the automatic transmission. Sometimes the automatic transmission can be destroyed.

It is considered to be particularly advantageous if the method according to the invention also provides that the variation of the power loss of the automatic transmission takes place as a function of the temperature of the internal combustion engine and / or of the temperature of the catalytic converter. In the simplest case, it is possible in this context, for example, to detect a cold start and to increase the power loss of the automatic transmission for a predetermined period of time. However, better results can be achieved if the power loss of the automatic transmission is varied in the form of a control and / or regulation. For example, one or more of the following temperatures may be considered in a controller and / or controller: catalyst temperature, engine temperature, transmission temperature.

In connection with the detection of a cold start, the method according to the invention preferably provides that the voltage of the belt part is increased during a cold start of the internal combustion engine and reduced again to a normal value after reaching a predetermined temperature of the internal combustion engine and / or the catalytic converter.

Any apparatus suitable for carrying out one embodiment of the method according to the invention falls within the scope of protection of the appended claims.

The device according to the invention corresponds to the generic state of the art insofar that the device for controlling and / or regulating the operating temperature of the catalytic converter varies the power loss of the automatic transmission. Similar to the erfindungsgmäßen method is based on the finding that the power loss of the automatic transmission affects the air flow rate through the engine and thus the operating temperature of the catalyst. The device also results in a lower increase in fuel consumption compared to a pure speed increase, since the power loss can be used directly to heat the automatic transmission. As a result, part of the initial losses can be recovered through consumption benefits over a total test cycle, similar to what has already been explained in connection with the method.

The variation of the power loss of the automatic transmission also takes place in the device by a variation of the friction losses of the automatic transmission. As a result, a fine metering of the power loss is given in connection with the device according to the invention. Furthermore, the power loss can be varied in this way in a wide range, as has already been explained in connection with the method according to the invention.

The device according to the invention builds on the generic state of the art in that the automatic transmission is a CVT transmission, which has a belt part serving for force transmission, and that the device for varying the power loss of the automatic transmission changes the tension of the belt part. It is considered to be particularly advantageous if it is provided in the device according to the invention that the variation of the power loss of the automatic transmission is additionally effected by a variation of the hydraulic losses of the automatic transmission. The belt part can for example be formed again by the initially mentioned push belt. The contact pressure or the tension of the belt part can also be adjusted in the case of the device according to the invention independently of the vehicle speed or the engine speed.

In this context, the device according to the invention preferably further provides that the device increases the tension of the belt part in order to increase the power loss of the automatic transmission. An increase in the tension of the belt part and thus of the contact pressure is not disadvantageous for example for a belt part in the form of a push belt, if the maximum additional pressure is not exceeded, as has already been explained in connection with the inventive method. The maximum additional pressure can be, for example, 30 to 50 bar, with low overdrive.

Similarly, the device according to the invention preferably further provides that the device reduces the tension of the belt part in order to reduce the power loss of the automatic transmission. A reduction in the power loss leads, as mentioned, to a reduction in the air flow rate through the internal combustion engine and thus to a slower heating of the catalyst or to a cooling of the catalyst. Even when reducing the tension of the belt part, a predetermined minimum value should not be undershot in order to avoid spinning or slippage of the belt part, for example between two bevel gear pairs. A spinning of the belt part can, as already explained in connection with the method according to the invention, possibly lead to damage or destruction of the automatic transmission.

It is considered particularly advantageous if it is further provided in connection with the device according to the invention that the device varies the power loss of the automatic transmission in dependence on the temperature of the internal combustion engine and / or on the temperature of the catalyst. In the simplest case, it is also possible in this context, for example, to detect a cold start and to increase the power loss of the automatic transmission for a predetermined period of time. However, better results can be achieved, as mentioned, when the power loss of the automatic transmission is varied in the form of a control and / or regulation. For example, one or more of the following temperatures may be considered in a controller and / or controller: catalyst temperature, engine temperature, transmission temperature.

In connection with the detection of a cold start, the device according to the invention preferably provides that the device increases the tension of the belt part in a cold start of the internal combustion engine and reduces back to a normal value after reaching a predetermined temperature of the internal combustion engine and / or the catalyst.

drawings

The invention will be explained in more detail with reference to the accompanying drawings.

Show it:

1 a flow chart illustrating the sequence of an embodiment of the method according to the invention,

2 3 is a schematic block diagram illustrating the interaction of the device according to the invention with an internal combustion engine and an automatic transmission in the form of a CVT transmission,

3 a column diagram illustrating the components of the power loss on the one hand as a function of the vehicle speed and on the other hand as a function of the contact pressure of a belt part, and

4 the influence of oil temperature on a test cycle consumption.

Description of the embodiments

1 shows a flowchart illustrating the flow of an embodiment of the method according to the invention. Here is the meaning of in 1 Steps S1 to S7 shown in the following table. step importance S1 begin S2 Detect catalyst temperature and / or engine temperature and / or transmission temperature S3 In step S2 detected temperatures within the respective target range? S4 Vary the power loss of the automatic transmission S5 Detect catalyst temperature and / or engine temperature and / or transmission temperature S6 In step S2 detected temperatures within the respective target range? S7 Set the power loss of the automatic transmission to a normal value

In the 1 illustrated embodiment of the method according to the invention begins in step S1.

In step S2, the catalyst temperature and / or the engine temperature and / or the transmission temperature is detected. For this purpose, for example, the later with reference to 2 explained temperature sensors 26 . 28 . 30 be used.

In step S3, the temperatures detected in step S2 are compared with predetermined threshold values. This makes it possible, for example, to detect a cold start. If all the temperatures detected in step S2 are in their respective desired range, no further measures are required and the process branches back to step S2. However, if it is determined during the comparison of the temperatures detected in step S2 with the corresponding threshold values that one or more of the temperatures detected in step S2 are outside their respective desired range, for example if there is a cold start, the system branches to step S4. In step S4, the power loss of the automatic transmission is varied. In the case of a CVT transmission is provided in this context, for example, that the voltage or the contact pressure of a belt part is increased in order to increase the power loss of the automatic transmission and thus the operating temperature of the catalyst. Accordingly, it can be provided to reduce the voltage or the contact pressure of the belt part when the power loss of the automatic transmission and thus the catalyst temperature to be reduced. The primary aim of the invention, however, is to enable a rapid heating of the catalyst, so that the reduction of the power loss of the automatic transmission to reduce the catalyst temperature has only a comparatively minor importance.

At step S5, all or some of the temperatures detected at step S2 are detected again.

In step S6, it is checked whether the variation of the power loss of the automatic transmission made in step S4 has already achieved the desired effect, which can be done by comparing the temperatures detected in step S5 with corresponding threshold values. If the desired effect has not yet occurred, a branch is made back to step S5. As soon as the desired effect of the variation of the power loss of the automatic transmission has occurred, a branch is made to step S7, in which the power loss of the automatic transmission is restored to a normal value, for example by setting the tension or the contact pressure of the belt part to a normal value. Subsequently, a branch is made back to step S2.

2 shows a schematic block diagram illustrating the interaction of the device according to the invention 20 illustrated with an internal combustion engine and an automatic transmission in the form of a CVT transmission. At the in 2 illustrated gear 10 it is a CVT transmission. This CVT transmission 10 includes two bevel gear pairs 32 . 34 and one as a push belt 12 designed wrap part. The bevel gear pair 32 is with an internal combustion engine 14 connected and is therefore as Antriebskegelradpaar 32 designated. The bevel gear pair 34 forms a driven bevel gear pair 34 by known coupling agents 36 with a driven axle 38 a motor vehicle is in communication. About the push belt 12 becomes a frictional connection between the drive bevel gear pair 32 and the driven bevel gear 34 manufactured, wherein for adjusting the translation and the voltage of the push belt each one bevel gear of Kegelradpaare 32 . 34 is moved in the axial direction. This displacement and bevel gears is controlled by a hydraulic system 16 caused by a hydraulic control 18 is controlled. In 2 is still a catalyst 24 indicated schematically, in an internal combustion engine 14 associated exhaust system is provided. The device according to the invention 20 , which may be part of an engine control and / or regulation, for example, stands with the hydraulic control 18 in conjunction and is thus able to influence the power loss of the automatic transmission by the voltage or the contact pressure of the thrust belt 12 is changed. In the 2 illustrated device 20 stands still with here not closer interested actuators 22 connected to the internal combustion engine 14 interact or are part of this. The catalyst 24 has a catalyst temperature sensor 26 on, which detects the temperature in the catalyst and the device 20 supplying a corresponding catalyst temperature signal. In the illustrated embodiment also includes the internal combustion engine 14 a temperature sensor in the form of an engine temperature sensor 28 on, with this engine temperature sensor 28 the device 20 supplying an engine temperature signal. Finally, in the illustrated embodiment also has the transmission 10 a temperature sensor in the form of a transmission temperature sensor 30 on. Although the transmission temperature sensor 30 as the hydraulics 16 is shown assigned, this transmission temperature sensor 30 also at other suitable points of the transmission 10 be arranged. The transmission temperature sensor 30 leads the device 20 a transmission temperature signal too. The device 20 can in conjunction with the catalyst temperature sensor 26 , the engine temperature sensor 28 and the transmission temperature sensor 30 for example, be designed in 1 illustrated embodiment of the method according to the invention perform. Regarding the functioning of in 2 The arrangement shown is therefore to avoid repetition in connection with the statements 1 directed.

3 shows a column diagram illustrating the components of the power loss on the one hand as a function of the vehicle speed and on the other hand in dependence on the contact pressure of a wrap-around part. The vehicle speed in km / h is plotted on the x1-axis. On the x2 axis is the contact pressure of the belt part 12 applied in cash. The respective power loss is plotted on the y-axis in kW, whereby the respective columns consist of the following power losses: pump losses PV, transformer losses WV, sliding friction losses GV, speed losses DV, contact losses AV, slip losses SV and friction losses RV. As already explained, it is possible with CVT transmissions to set the contact pressure or the tension of the belt part independently of the vehicle speed or the engine speed. 3 illustrates in this context, for example, that the power loss of the automatic transmission at a contact pressure of 6 bar, the power loss of the automatic transmission can correspond, which would normally result at 30 km / h. The same relationships apply to a contact pressure of 7 bar and a vehicle speed of 100 km / h or a contact pressure of 9 bar and a vehicle speed of 140 km / h.

4 shows the influence of the oil temperature on a test cycle consumption. The test cycle is the so-called IG 96 cycle, which starts at 20 ° C. On the x-axis of 4 the number of inner-city cycles is plotted, while on the y-axis the consumption reduction is plotted in percent. The temperatures shown are each the oil temperature. The representation of 4 It can be seen that the accumulated consumption at the end of the fourth urban phase has been reduced by 18% compared to the first phase. The oil temperature has risen from 20 ° C to 48 ° C. This relationship makes it clear that the solution according to the invention allows part of the initial losses to be recovered by means of consumption advantages over the entire test cycle, as already explained. This results overall in a smaller increase in fuel consumption, compared to influencing the operating temperature of the catalyst via a pure speed increase. This is due in particular to the fact that the power loss of the automatic transmission in the solution according to the invention can be used directly for heating the transmission.

The foregoing description of the embodiments according to the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

Claims (10)

Method for influencing the operating temperature of a catalyst ( 24 ), in particular for rapid heating of the catalyst ( 24 ), an internal combustion engine ( 14 ) having motor vehicle with automatic transmission ( 10 ), wherein the operating temperature of the catalyst ( 24 ) by varying the power loss of the automatic transmission ( 10 ), characterized in that the automatic transmission ( 10 ) a CVT transmission ( 10 ) is that which serves for transmitting a force transmission part ( 12 ), and that for varying the power loss of the automatic transmission ( 10 ) the tension of the wrapping part ( 12 ) is changed. Method according to one of the preceding claims, characterized in that the tension of the wrapping part ( 12 ) is increased to the power loss of the automatic transmission ( 10 ) increase. Method according to one of the preceding claims, characterized in that the tension of the wrapping part ( 12 ) is reduced to the power loss of the automatic transmission ( 10 ) to reduce. Method according to one of the preceding claims, characterized in that the variation of the power loss of the automatic transmission ( 10 ) as a function of the temperature of the internal combustion engine ( 14 ) and / or the temperature of the catalyst ( 24 ) he follows. Method according to one of the preceding claims, characterized in that the tension of the wrapping part ( 12 ) at a cold start of the internal combustion engine ( 14 ) and after reaching a predetermined temperature of the internal combustion engine ( 14 ) and / or the catalyst ( 24 ) is reduced back to a normal value. Contraption ( 20 ) for controlling and / or regulating the operating temperature of a catalytic converter ( 24 ), in particular for rapid heating of the catalyst ( 24 ), an internal combustion engine ( 14 ) having motor vehicle with automatic transmission ( 10 ), the device ( 20 ) for controlling and / or regulating the operating temperature of the catalyst ( 24 ) the power loss of the automatic transmission ( 10 ), characterized in that the automatic transmission ( 10 ) is a CVT transmission, which serves a power transmission Umschlingungsteil ( 12 ), and that the device ( 20 ) for varying the power loss of the automatic transmission ( 10 ) the tension of the wrapping part ( 12 ) changed. Contraption ( 20 ) according to claim 6, characterized in that the device ( 20 ) the tension of the wrapping part ( 12 ) to reduce the power loss of the automatic transmission ( 10 ) increase. Contraption ( 20 ) according to one of claims 6 to 7, characterized in that the device ( 20 ) the tension of the wrapping part ( 12 ) to reduce the power loss of the automatic transmission ( 10 ) to reduce. Contraption ( 20 ) according to one of claims 6 to 8, characterized in that the device ( 20 ) the power loss of the automatic transmission ( 10 ) as a function of the temperature of the internal combustion engine ( 14 ) and / or the temperature of the catalyst ( 24 ) varies. Contraption ( 20 ) according to one of claims 6 to 9, characterized in that the device ( 20 ) the tension of the wrapping part ( 12 ) at a cold start of the internal combustion engine ( 14 ) and after reaching a predetermined temperature of the internal combustion engine ( 14 ) and / or the catalyst ( 24 ) is reduced back to normal.

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