JPS5928729B2 - Automotive catalyst temperature warning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an abnormal temperature rise warning device for a catalyst in an exhaust gas purification device for an automobile.

Conventional catalyst abnormal temperature rise alarm systems use a method in which a temperature sensor using a thermistor and a thermocouple is inserted to measure the temperature of the catalyst bed or the exhaust downstream of the catalyst, and the temperature is directly measured. .

In some cases, the floor temperature of the car near the catalytic converter is measured using a thermistor thermocouple (see Nissan Motor Co., Ltd. Service Bulletin No. 287, October 1975).

However, since such conventional catalyst temperature detectors are directly attached to catalytic converters, they are exposed to vibrations and high temperatures, and are made of highly heat-resistant alloys to withstand corrosion from road mud, salt, etc.

Since the lead wire is covered with a sealed sheath, an expensive detector must be used, resulting in high costs.

Furthermore, if a catalytic converter is added near the engine, it will be exposed to higher temperatures than an underfloor converter, and at the same time will be subjected to vibrations and accelerations comparable to IOC, making the above problem even more serious.

This invention was made by focusing on these conventional problems, and detects the temperature of the catalytic converter by using a detector installed opposite to the infrared rays radiated by the catalytic converter, without directly adding the temperature pickup to the catalytic converter. The purpose of the present invention is to solve the above-mentioned problems by performing measurements using this method.

The present invention will be explained below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention, in which 1 is an engine, 2 is an exhaust manifold, 3 is a catalyst, 4 is an exhaust outlet of a catalytic converter, and 5 is an infrared detector. The catalytic converter is either added to the engine's cylinder block opposite the catalyst position using rubber, or is attached to the vehicle body.

6 is an amplifier, 7 is a comparator, 8 is a warning lamp drive circuit, 9
is a warning lamp mounted on the instrument panel.

Next, the effect will be explained.

Generally, objects emit infrared rays depending on their temperature.

As shown in FIG. 2, as the temperature increases, the maximum radiation value shifts to the shorter wavelength, and at the same time, the radiant energy value increases.

This relationship between wavelength and temperature follows Wien's law (λmT=constant, 2m maximum wavelength, T absolute temperature).

When the temperature of the catalyst rises, the temperature of the exhaust gas that has passed through the catalyst also rises, and infrared rays are radiated from the surface of the catalyst 3, which is received by the detector 5, which causes an alarm lamp 9 to issue an alarm as described later.

Generally, the shape of the catalytic converter is narrowed at the outlet of the catalytic converter as shown in FIG. 3, so the exhaust gas imparts heat to the wall and the temperature of this cone portion rises.

The catalyst temperature and the surface temperature of the cone portion at the outlet of the catalytic converter are approximately proportional.

In this way, the infrared rays radiated from this surface are measured and an alarm is issued when the catalyst temperature reaches a high temperature.

Also, if the catalyst becomes abnormally high temperature, the difference between the catalyst inlet surface temperature and the catalyst outlet surface temperature will be extremely different; in such a case, the temperature values at the catalyst inlet and outlet will be different. come.

In such cases, in order to measure both accurately, a heat-resistant (quartz) glass 10 is embedded in the catalytic converter case as shown in Figure 4, and the infrared rays radiated from the exhaust gas are transmitted through this glass separately from the one shown in Figure 1. By measuring the temperature of the exhaust gas itself using the provided infrared detector, abnormal high temperatures in the catalytic converter can be detected and an alarm can be issued.

As can be seen from FIG. 2, differences can be found even when measuring the overall infrared beam, but if a filter is provided to catch the hatched portion in FIG. 2, the detection sensitivity will be increased.

Ordinary glass is also a good filter when detecting temperatures of 900 to 1000°C.

Since infrared filters are usually expensive, it is more practical to increase the sensitivity of the detector and use a low-cost filter such as glass.

The infrared detector 5 needs to be resistant to vibrations and atmosphere, and a thermocouple type detector that captures infrared rays is most suitable.

The infrared detector 5 may be one with a built-in correction to remove the influence of ambient temperature, or one with a correction circuit.

However, in the present invention, since the detector is not directly attached to the catalytic converter, the heat resistance may be lower than that of the conventional one, for example, it is sufficient to withstand 100 to 200'C, and therefore it is not as expensive as the conventional one. .

For example, it may be made of ceramic printed with tungsten or the like.

Referring again to FIG. 1, the output of the infrared detector 5 is transmitted to the amplifier 6.
The voltage is amplified by the comparator 7 and compared with a predetermined voltage (a value corresponding to the temperature that requires an alarm).
The alarm lamp 9 on the instrument panel inside the vehicle is lit.

FIG. 5 shows another embodiment.

In this embodiment, the temperature at the inlet of the catalyst and the temperature at the outlet of the catalyst are compared by infrared detectors 5', 5, and an alarm is issued when the temperature exceeds a set value.

Even if the detectors 5' and 5 are placed at the same distance from the catalyst inlet and outlet as shown in Fig. 5, the detectors 5' and 5 are placed at one place as shown in Fig. 6.
', 5 may be synthesized and put together.

In cases where the catalyst is burnt out, the temperature difference between the inlet and outlet becomes a very large value.

This is judged by the radiation at the entrance and exit.

Lenses 11 and 11 are arranged opposite to each other on the catalyst inlet side and the catalyst outlet side, respectively.

As explained above, according to the present invention, an infrared detector is used and placed in a non-contact manner on the catalytic converter, making it cheaper and more reliable than conventional high-temperature thermistors or thermocouple thermometers that can withstand high temperatures and vibrations. This gives you the advantage of being able to roam around alarm devices that have alarms.

[Brief explanation of the drawing]

Figures 1, 5, and 6 are detailed diagrams explaining the present invention, Figure 2 is a diagram showing the relationship between the wavelength of infrared rays emitted from an object, radiant energy, and temperature, and Figure 3 is a diagram of the catalyst device. A cross-sectional view of Figure 4A. Each opening is a sectional view of an example of an infrared detection device, and in FIG. 6, A is an enlarged view of part A of the mouth and a system diagram. 1... Engine, 2... Exhaust manifold, 3... Catalyst, 4... Exhaust outlet, 5, 5'...
Infrared detector, 6... Amplifier, 7... Comparator, 8.
...Alarm lamp drive circuit, 9...Alarm lamp, 10.
...Heat-resistant (quartz) glass, 11...Lens.

Claims (1)

[Claims] 1. An automobile exhaust purification device having an exhaust purification catalyst, which detects the catalyst temperature by detecting infrared rays radiated from the vicinity of the catalytic converter, and issues an alarm when the catalyst temperature rises abnormally. Alarm device.