DE29504088U1 - On-board diagnostic / OBD / device on a micro scale for the continuous measurement of pollutant discharge from motor vehicles - Google Patents

Description

On-board diagnostics (OBD) device for continuous measurement of pollutant emissions from motor vehicles

1. Brief description of the utility model

Motor vehicles burn hydrocarbon mixtures, producing substances that are relevant to the environment, such as carbon dioxide (C02), carbon monoxide (CO), nitrogen oxide (NOx) and partially oxidized hydrocarbons (CH compounds). Today, their continuous recording is carried out exclusively with large stationary devices in the workshop or laboratory. Mobile devices for on-site use are not yet available. The reason for this hesitant development is the rough conditions in traffic and the very short T90 times, in the tenths of a second range. It is therefore only possible to record the acceleration and combustion processes in the combustion engine with fast analyzers.

The present utility model consists of a gas analyzer in the engine compartment, which measures the concentration of the four most important pollutants in the exhaust gas flow in a bypass using infrared (IR) absorption. A replaceable filter is installed upstream of the analyzer to clean the exhaust gas flow and a Peltier cooler to dry it.

The measurement signals are stored in the microcontroller module (26) which is installed in the dashboard of the driver's compartment (see Fig. 3). The memory card (27) is used to retrieve the stored values, from which they are read into a PC. This is where the signal curve of all pollutant components is evaluated and graphically displayed. It is possible to record even more data, as the microcontroller has several analysis inputs (serial interface (25)).

The collected values could form the basis for an emissions-based tax assessment.

2. State of the art

Pollutants are not currently detected in the motor vehicle itself, whether it is a car or a truck. Their pollutant emissions are recorded in the static state during the exhaust emission tests. This gives rise to two problems:

- the dynamic load on the engine deviates from the static state on the test bench during the journey,

- the measurements taken during the exhaust emission tests do not rule out adjustments, i.e. worsened exhaust emissions in subsequent road traffic.

At present, neither the traffic police nor the environmental agency are able to carry out such measurements in road traffic. There is not only a lack of roadworthy measuring devices, but above all of portable devices for in-situ monitoring of pollutant emissions.

The vehicle tax is calculated based on engine capacity. However, since engines of the same size and type can behave very differently between individual emission tests, this type of taxation is not environmentally friendly. This could be achieved, however, if the tax were based on the total absolute pollutant emissions. However, the recording devices that would enable long-term recording of concentrations are not available.

3. Detailed description of the device

The gas sampling probe (2) with the heat-resistant, replaceable filter (3) is installed in a bypass of the exhaust pipe (1) (see Fig. 1). The filter retains the coarse dirt particles. The exhaust gas is sucked through the air cooler (4) and the Peltier cooler (7), which ensures that the gas is sufficiently dried, by means of the gas pump (21) (see Fig. 3). The condensate pump (5) (see Fig. 1) disposes of the condensate via the drain (6). The now dry and cleaned exhaust gas is sucked through the optical cuvette (8).

The cuvette (see Fig. 2) contains the radiator (or several radiators) (9), which deliver a pulsed heat flow to the pyroelectric or semiconductor measuring cell (11) in a clocked or chopped manner. The clock frequencies are only selected to be fast enough to ensure the optimal natural frequency of the cell (e.g. with about f=1Hz). By switching between several cuvettes that are flowed through simultaneously but are clocked one after the other with a time delay of e.g. 0.1...0.2 seconds, a fast reaction with T90 times in the 0.1...0.25 second range is achieved. The measurement is carried out using the comparison method, i.e. 2 IR-sensitive measuring cells, e.g. 2 pyroelectric detectors, are always installed in the optical cuvette. Measuring cell 1 (10) receives the gas to be measured, measuring cell 2 (14) measures a comparison band without IR absorption. The use of multiple gas detectors with two or more sensors and corresponding narrow band filters is of course also possible. The gas is supplied and discharged via couplings (12) and (13) (see Fig. 2).

The clocked voltage signals from the IR analyzer (8) are amplified and sent together with the values from the pressure sensors (15) and (16), the temperature sensors (17) and (18), the humidity sensor (19) and the volume flow sensor (20) to the microprocessor (26) (see Fig. 3). This is installed in the dashboard of the vehicle (see Fig. 8). It receives the pulsed and amplified measurement signals from the IR analyzer via protected, shielded cables. In the μ�R (26) the peak areas of the individual measurement signals are evaluated by forming a quotient or dividing them (see Fig. 3).

If a limit violation is registered, the device informs the driver on the display that a workshop must be visited (see Fig. 4).

The data is stored according to the time it is generated. If the memory is about to be exhausted, a warning message is issued and the collected data must be read out using the memory card (27). If a memory card is lost or destroyed, the data still in the ring buffer and not overwritten can be read out using the laptop or notebook (34) via the serial interface (Fig. 3 and 5).

The data from the memory card (27) is read into the LCD (22) of the device and/or into a PC by a reader, saved and displayed in tabular and graphic form (see Fig. 6 and 7). An authorized workshop or the TÜV sends the data to the tax office by modem or post for billing purposes. Fig. 8 shows how the recording device is installed in the dashboard.

The device is calibrated at petrol stations or in authorized workshops. Small test gas canisters with the appropriate filling are available for this purpose. The calibration canister is connected to the analyzer using a hose nipple. After the test gas has been introduced into the analyzer, a message appears on the display (22) with a comparison of the target and actual values. This data is also saved and can be taken into account when evaluating the measurement reports. Drivers can also carry out their own calibration.

4. Advantages of the continuous gas analyzer

In the future, it would make sense for vehicles to continuously record and record their pollutant emissions. This could help to ensure that vehicle tax is set in an environmentally friendly manner. However, such a device would result in a whole chain of changes in the infrastructure of both the oil industry and the monitoring bodies. The filling stations would have to have reading stations with protocol evaluators and printers and would also have to be able to calibrate the devices installed in the vehicles. They could also offer the small calibration containers required for self-monitoring.

The CO2 band is used as a reference band. The other channels (e.g. for CH, CO and NO) are adjusted proportionally when setting the sensitivity based on the CO2 measurement, which can be carried out without calibration gases, just with ambient air.

The evaluation of the collected data on the PC then provides the basis for vehicle taxation. The advantages are obvious: You get an exact record over a longer period of time and not just of isolated loads during the AU inspection, which is due every one or two years. The actual driving behavior and not just the static load on the test bench is determined. Both facts are technically and ecologically more advantageous than just testing on the occasion of the AU.

The data acquisition module in the dashboard has a particularly advantageous feature with warning functions for the driver. If a limit state is reached, this is signaled while driving. If the warning is ignored, the omission will be evident during the next evaluation according to the marking in the memory, i.e. on the memory card.

The device presented can contribute to environmentally friendly taxation of vehicles and to an environmentally conscious driving style of drivers.

Fig. 1 Gas flow diagram

1) Exhaust pipe

2) Measuring line

3) Filter

4) Air cooler

5) Condensate disposal pump

6) Condensate drain

7) Peltier cooler

8) IR microanalyzer

Fig. 2 ER analysis cuvettes arranged in rows

9) Spotlights

10) Cuvette 1

11) pyroelectric detector

12) Gas supply coupling

13) Gas discharge coupling

14) Cuvette 2

Fig. 3 Primary (—) and secondary (-.-.-.) circuits connected to the microcontroller

15) Pre-pressure sensor

16) Back pressure sensor

17) Input temperature sensor

18) Output temperature sensor

19) Humidity sensor

20) Volume flow sensor

21) Gas pump

22) LCD panel in the dashboard

23) Dashboard keypad

24) Power supply

25) serial interface

26) Microcontroller

27) Memory card

Fig. 4 Possible screen avoidance

28) Button for activating the screen /

Switch on query

29) Calibration button

30) Zero point adjustment

31) Sensitivity adjustment

32) Scrolling forward in time

33) Scrolling backwards in time

Fig. 5 Connecting a mobile computer to the serial interface

34) Laptop or notebook

Fig. 6 Representation of a measured value curve in a time grid

Fig. 7 Representation of the absolute pollutant emissions as a bar chart of a period

Fig. 8 Installation of the data acquisition module in the dashboard

35) Dashboard

36) Housing for the data acquisition module

37) Memory card holder

Fig. 9 Time-shifted timing of the HI emitters of the individual cuvettes in the tenths of a second range to reduce the T90 time

Claims (9)

&bull;&bull;&bull;*S*<KLte*"*5· ·«*··· Claim points 1. On-board diagnostic (OBD) device on a microscale for the continuous measurement of pollutant emissions from motor vehicles, characterized in that the measurement is carried out on the basis of infrared gas absorption without moving parts in the optical path, by electronic timing of the radiation source. OBD device according to main claim 1, characterized in that da/3 2. several cells arranged in parallel are used, which are simultaneously flowed through by the exhaust gas, but are switched through periodically by the time-shifted clocking of the emitters one after the other, so that the resulting t90 time (despite the inertia of the individual measuring cells in the second range) is in the tenths of a second range and the rapid processes in the vehicle exhaust gas can be recorded. 3. the Me/3 gas is filtered and cooled before entering the IR cuvette and is provided with control sensors in each section. 4. Equipping the vehicle with a large number of sensors not only helps to identify limits for pollutant emissions/3 but also to isolate errors, i.e. to carry out self-diagnosis in the vehicle. 5. OBD device, in which the calibration of the IR cuvettes is carried out even without suitable test gases simply by adjusting the channels CH, CO and NO etc. to the calibration of the sensitivity of the C02 channel by proportional shift. A particularly advantageous feature of this method is the presence of C02 at the same concentration in the atmosphere. 6. In the OBD device, the Me/3 data are evaluated in a μ�R according to the quotient formation method, whereby the data is stored on an external memory card in addition to the internal RAM. OBD device, according to main claim 6, characterized in that/3 7. the evaluation of the collected data in specialist workshops and at petrol stations can be carried out using a device that sends the data to the tax office by modem or by post for tax accounting purposes. 6* 8. an evaluation and communication system is installed in the driver's compartment, in the dashboard with visual display options, with control elements and memory card. 9. a warning signal is given when the memory capacity of the microcomputer module is approaching exhaustion, when limit values are reached and exceeded, when calibration or other monitoring work on the system is necessary.