This application claims the priority of German patent document 10 2004 015 044.3, filed Mar. 26, 2004 (PCT International Application PCT/EP205/003095, filed Mar. 23, 2005), the disclosure of which is expressly incorporated by reference herein. 
The invention relates to a method for detecting the presence of a prescribed heat exchanger, in particular a catalytically active radiator in a motor vehicle, and to an apparatus for this purpose which has at least one heat exchanger, at least one measuring device, and an evaluation device. 
So-called catalytically active radiators are frequently provided in modern motor vehicles.  A catalytically active radiator for the coolant of a vehicle motor has an additional coating which catalytically converts ozone that is present in the air which onto the vehicle and flows through the radiator, into harmless oxygen.  Such catalytically active radiators are sometimes also known by the trade name “PremAir radiator™”.  Catalytically active radiators of this type have been developed particularly with regard to better environmental compatibility of the materials used and to avoid the undesired ozone, and therefore often satisfy the corresponding relevant environment regulations. 
In many countries, the use of a catalytically active radiator in a motor vehicle is subject to special statutory regulations.  In particular, tax benefits are often granted when such radiator elements are used since these radiators have a lesser effect on the environment on account of the conversion of harmful ozone into atmospheric oxygen.  However, such radiator elements are relatively expensive, which often offsets the advantage of the tax saving.  As a result, there is an incentive to replace the expensive radiator in the motor vehicle (which results in a tax saving), with a comparatively low-cost radiator under certain circumstances.  It is therefore necessary to ensure that an installed catalytic radiator cannot be exchanged for a conventional radiator without activation of a safety unit (for example, an on-board diagnosis (OBD) system).  That is, the comparatively expensive radiators should therefore be protected against adulteration and manipulation. 
European patent document EP 1 153 646 A1 discloses a motor vehicle with a radiator having a catalytic coating, in which a control unit with an associated sensor system controls operation of the radiator and informs the user about the state or operation of the radiator.  The sensor system also has temperature sensors at different locations in the cooling system.  This publication does not, however, describe securing the radiator against manipulation, or disclose a method for detecting manipulation, for example by means of temperature sensors. 
Temperature-measuring devices for cooling water also have sensors which measure the absolute temperature of the cooling water after opening of the thermostat, which guides the cooling circuit past the radiator for a certain time in the closed state after the motor is started, and through the radiator after it is opened.  One disadvantage of this arrangement is that the characteristics of the thermostat change over time, and an absolute measurement of the cooling-water temperature is not suitable for detecting the installation of a catalytically active radiator as opposed to a conventional radiator. 
One object on which the present invention, therefore, is to provide a method and apparatus for detecting reliably the presence of a prescribed heat exchanger, particularly a catalytically active radiator in a motor vehicle. 
This and other objects and advantages are achieved by the method according to the invention which includes the following method steps during operation of the motor vehicle:
(S1) observing the temperature of a heat-exchanger medium and at the same time observing further current operationally relevant parameters of the motor vehicle for a given time window;
(S2) detecting an expected time gradient of the temperature of the heat-exchanger medium;
(S3) detecting the current time gradient of the temperature of the heat-exchanger medium; and
(S4) detecting the presence of a prescribed heat exchanger by taking into account the expected and current time gradients. 
In addition, the invention also includes an apparatus for detecting the presence of a prescribed heat exchanger, in particular a catalytically active radiator in a motor vehicle, which includes:                at least one heat exchanger with a heat-exchanger medium of the motor of the motor vehicle;        at least one measuring device for measuring the temperature of the heat-exchanger medium; and        an evaluation device for evaluating data and for detecting the presence of a prescribed heat exchanger.         
The idea on which the present invention is based involves integrating a temperature sensor in a heat exchanger, such that the temperature sensor can be used to measure a specific absolute temperature gradient over time of the heat-exchanger medium in specific operating states of the engine.  When a heat exchanger is manipulated, a different temperature gradient is measured, and an evaluation algorithm performed to draw a conclusion regarding the presence of a catalytically active radiator.  This results in the following advantages:
The relevant statutory regulations regarding exhaust-gas standards and environmental protection can be satisfied by establishing the presence of a catalytically active radiator by measuring an absolute temperature gradient. 
A change in the characteristics of the thermostats has no effect on the measurement result. 
Manipulations can be uncovered and economic loss can be avoided. 
The inventive apparatus provides further advantages:
An attempt to remove a temperature sensor from the apparatus leads to irreversible damage to the sensor. 
If the temperature sensor is cut out off a catalytically active radiator which is no longer operable, or forcibly removed in some other way (since it cannot be easily removed on account of the inventive apparatus, and is fitted in the engine compartment, for example to a coolant tube or to a conventional exchange radiator), this is reliably identified by the inventive method. 
The illegal installation of a conventional radiator instead of a prescribed catalytically active radiator is therefore prevented. 
In one preferred embodiment, method step S1 comprises the following substeps:
(S1-1) measuring values of the temperature of the heat-exchanger medium in predefined time intervals and plotting the time profile of these values; and
(S1-2) measuring values of the operationally relevant parameters at predefined time intervals and plotting the time profiles of these values. 
The operating state of the motor vehicle in the time window can thus be advantageously determined. 
A further refinement of the invention provides for the following the substeps in the method step S2:
(S2-1) comparing the plotted current operationally relevant parameters with predefined values;
(S2-2) determining an associated current operating state in accordance with this comparison; and
(S2-3) determining the temperature gradient expected in this current operating state. 
The operating states can advantageously be determined from tables by means of stored data, and it is also possible to determine the expected temperature gradient in a simple manner. 
In one further embodiment, the current temperature gradient is detected in method step S3 by taking into account the current values of the temperature of the heat-exchanger medium plotted in the time window. 
Method step (S4) advantageously comprises the following substeps:
(S4-1) comparing the current temperature gradient with the expected temperature gradient;
(S4-2) taking into account this comparison result with reference to a predefined threshold value; and
(S4-3) transmitting data signals when a prescribed heat exchanger is present. 
In a further refinement of the present invention, method step S4 comprises the following substeps:
(S4-1) comparing the current temperature gradient with the expected temperature gradient;
(S4-2) taking into account this comparison result with reference to a predefined threshold value;
(S4-3) incrementing at least one counter in accordance with the comparison result from substep (S4-2);
(S4-4) carrying out method steps (S1) to (S4-3) until a predefined counter reading is reached; and
(S4-5) outputting data signals when a prescribed heat exchanger is present. 
The plausibility of the measurement results can therefore be checked and the measurement results can, for example, be transmitted to a so-called on-board diagnosis system by advantageously carrying out the method more than once. 
It is advantageous for another inventive embodiment to provide for the time window to be determined to begin at a first time when at least one operationally relevant parameter reaches a predefined starting threshold value, and for the time window to be determined to end at a second time when the same, or at least one further operationally relevant, parameter reaches the same or a further predefined ending threshold value. 
In a further embodiment of the invention, the measuring device of the apparatus has at least one temperature sensor for measuring the temperature of the heat-exchanger medium; a holding element for holding the temperature sensor; and a connection device for connection to the evaluation device. 
Furthermore, it is particularly advantageous for the holding element to be connected to the heat exchanger in a non-releasable manner, so that unauthorized removal is prevented in a simple manner. 
According to another embodiment of the invention the element for holding the temperature sensor has a holder which corresponds to said temperature sensor. 
It is also advantageous for the temperature sensor to have a predetermined breaking point, and to be connected to the holding element such that it is rendered permanently inoperable after it has been removed from the holding element. 
The temperature sensor is expediently a constituent part of an adapter of the connection device in this case. 
It is particularly advantageous for the adapter and the holding element to have corresponding fastening elements which are designed such that they cannot be released following assembly, since this provides an additional way of preventing manipulation. 
In a further embodiment of the invention, the evaluation device has a memory device for storing values of time profiles of measured values, a data memory for storing predefined threshold values, operating state data and the like, and at least one counter. 
The evaluation device is advantageously a constituent part of an on-board computer (ECU) of a motor vehicle. 
The method allows a reliable conclusion to be drawn regarding the positioning of the temperature sensor and therefore whether a catalytically active radiator is present, by measuring the temperature gradient in a predefined value range.  In addition, the inventive apparatus provides advantageous ways of preventing manipulations. 
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.