JPS6258603A - Thermistor for detection of exhaust gas temperature - 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 [Field of Application of the Invention] The present invention relates to a thermistor for detecting exhaust gas temperature, and particularly to a thermistor that is less affected by exhaust gas composition and can accurately detect exhaust gas temperature.

[Prior Art] A thermistor is known in which a metal oxide semiconductor such as TiOH is tightly sintered to cut off contact with exhaust gas (
For example, Japanese Patent Application Laid-open No. 129742/1982). This thermistor uses dense sintering to delay response to changes in exhaust gas composition, making it appear less sensitive to exhaust gas composition. However, according to this publication, when the atmosphere is switched between the rich side (region where the equivalence ratio λ is 1 or less) and the rich side (region where the equivalence ratio λ is 1 or more), the resistance value of the thermistor changes in 1 second. It changes by about 4 times. Note that the measurement temperature was 710°C.

[Problem of the Invention] An object of the present invention is to obtain a thermistor with a small detection error due to exhaust gas composition.

[Structure of the Invention] The thermistor for detecting exhaust gas temperature of the present invention is made of compound A.
SnO3 (where A is Ba, Sr, Ca.

represents at least one member of the group consisting of and Ra. ), 0.03 to 05 gram atoms per mole thereof, Mn,
Cu, WSTa, Co, Ga, Nb5Zn.

[Example] BaC0:+, 5rCOz, CaCO3, Ra CO3
was mixed with an equimolar amount of SnO2 and heated in air for 4 hours.
Calcinate at 00°C to form perovskite compound f3asno
s, 5rSn():+, casnO:+, RaSn
I got 03. After pulverizing the compound, an oxide such as manganese was added and press molding was performed at 300 atmospheres to form a pellet in which a pair of electrodes was embedded. The pellets were sintered at 1400°C for 4 hours in air. The resulting beret is dense;
It had almost no pores.

It is presumed that a part of the added oxide penetrates into the Belobstite compound and becomes solid solution or substitute, and most of it precipitates as an oxide. The existing forms of oxides include manganese as Mn t 03 and MnaO, copper as CuO and CLI20, tungsten as W 03, tantalum as Ta205, cobalt as Coo and Co5t, gallium as Ga2O3, niobium as Nb 205, and zinc as oxide. ZnO
, Nickel is estimated to be Nip, and chromium is estimated to be C203.Also, the conditions for calcination and sintering can be changed as appropriate.

As another example, BaS with manganese oxide added
No. 3 was press-molded at 30 atm to obtain sintered No. 3. In addition, as a comparative example, one was produced without adding an oxide such as manganese.

Using these pellets, the thermistor (2) in Figure 1
was manufactured. In the figure, (4) is a substrate made of alumina, etc.
(6) is a pellet, (8), (10) are electrodes, (12)
, (14) are external leads.

The characteristics of the thermistor (2) were investigated. The thermistor (2) was placed in an atmosphere with an equivalence ratio λ of 11 (lean) or an atmosphere with an equivalence ratio of 0.9 (rich), and the temperature was raised from 300°C to 800°C at a rate of 10°C/min. Warm up. The resistance value during this time was measured and the characteristics of the thermistor (2) were evaluated.

Figure 2 shows Ba5nO3 with manganese added (press pressure 30
0 atm). In addition, below, Ba5n-03
For 1 mole of etc., the metal in the added oxide is 0.0
1 gram atom is 1 mole%, or simply 1
Display as %.

When 10% manganese is added, sensitivity to exhaust gas composition is lost and it can be used as an accurate thermistor.

For comparison, the results of plain B a S n 03 are shown.

Figure 3 shows the results of r3asno* with 10% copper added.
Figure 1 shows the results for SrSnO3 with 10% manganese added, and Figure 5 shows the results for Ca5n-0 with 10% manganese added.
The results of 3 are shown below. In either case, the influence of exhaust gas composition is small;
Can accurately detect temperature.

The results of each example are summarized in Tables 1 and 2.

Table 1 13aSn03 system R1/Rr3) Not) Additive 2) 700'C800'
C1* Mn15 IQ2
Mn 5 2 33
Mn1O1,71,84Mn30 1
．． 3 1.454) Mn10 2
2.56* Mn1O00,3 7* Cu I 6 1
08 Cu10 2.1 2.
39 WIo 1.8 2.
010 Ta10 2 2.5
11 Co10 2.5 412
Zn104 613*
TiO210300 14* 5nO210350 1) Main +A materials are all BaSnO3, * is comparative example, 2) Mol% unit, 3) Lean side (λ is 1.1) and ridge side (λ is 09)
4) Press pressure 30 atmospheres.

Table 2 Other semiconductors 1) R1/Rr Semiconductor 2) Additives 700°C 800'C
3rSnO3* Mn 1 5 9/l
Mn10 1.3 1.5”
Cu10 1.2 1.5 WIO1
,3+,5 〃Co10 2 2.5 〃Ga1O22,8 〃Zn10 3 4 〃Ni1O34 Horn Cr1Q 3
4 Table 2 continued flll/Rr 弘弘±2) Additives 700°C800°CC
aSnO3* Mn I 5 8〃Mn
1O1,41,6 〃Cu 5 l 6 2 〃Ta1O1,31,5 〃Col0 1.5 2.3 〃Ga10 1.6 2.3 ” Nb10 1.5 2.2RaSn0
3Mnl O1,82 1) Measurement conditions are the same as in Table 1. 2) * indicates a comparative example.

The following can be seen from the results in each table. For addition of oxides such as manganese, 1% is insufficient, but 5%
%, a sufficient effect can be obtained (Samples I and 2 in Table 1). On the other hand, if you add 100% manganese, the thermistor will be Ba5.
It exhibits properties similar to manganese oxides such as nOs (Sample 6 in Table 1).

When considering the types of oxides, manganese, copper, tungsten, and tantalum exhibit similar properties and are most effective. This is followed by cobalt, gallium, and niobium, with zinc, nickel, and chromium being somewhat less effective.

[Effects of the Invention] The present invention provides a thermistor that is less affected by exhaust gas composition and can accurately detect the temperature of exhaust gas.

[Brief explanation of the drawing]

FIG. 1 is a front view of a thermistor for detecting exhaust gas temperature according to an embodiment, and FIGS. 2 to 5 are characteristic diagrams of the embodiment.

Claims (1)

[Claims] (1) Compound ASnO_3 (where A is Ba, Sr
, Ca, and Ra. ), Mn, Cu, W, Ta, Co, Ga, Nb, Zn, Ni
, Cr, and the amount added is equivalent to the metal element in the oxide.
A thermistor for detecting exhaust gas temperature, characterized in that it contains 0.03 to 0.5 gram atoms per mole.