JPS6326244B2 - - Google Patents

Abstract

PURPOSE:To prevent catalyst charged in an exhaustion passage of an engine from being possoned by phosphorus by placing in a passage of engine oil a member which adsorbs phosphorus contained in the engine oil. CONSTITUTION:In a lubricating system, engine oil in an oil pan 2 at the bottom of an engine 1 is compressed by a pump 3, passes through an oil filter 4 and is supplied to each lubricating parts. Material like gamma-aluminum oxide, delta-aluminum oxide, activated charcoal, or MgSO4, which is generally used as catalyst to purify exhaust gas serves as an agent for adsorbing phosphorus. The agent 7 enclosed by a wire net 6 is secured with fixtures 8 to the bottom of the oil pan 2 where an engine oil is hot. As the adsorptivity is increased at high temp, phosphorus in engine oil can be effectively removed.

Description

[Detailed description of the invention]

The present invention relates to an exhaust gas purification catalyst protection device that protects a catalyst used in a catalytic exhaust gas purification device provided in an engine exhaust system from phosphorus poisoning. Generally, automotive engine oil contains Zn, Pb, etc. to prevent oxidation, wear, and corrosion.
Compounds such as Ca and P are added as additives. By the way, when this type of engine oil leaks into the combustion chamber of the engine due to deterioration of oil seals, etc., or is brought directly into the combustion chamber and is burned together with the air-fuel mixture in the combustion chamber, the oxides of the additives mentioned above are produced. Combustion ash is produced. Among this type of combustion ash, it is known that when the amount of phosphorous oxide P ₂ O ₅ increases, it significantly impairs the purification performance, that is, the catalytic function, of the exhaust gas purification catalyst device installed in the exhaust system of the engine. This phenomenon is generally called "phosphorus poisoning" phenomenon, and it is because phosphorus oxide P ₂ O ₅ , which is once generated by combustion, combines with zinc oxide ZnO at high temperature, and becomes ZnP ₂ O ₆ . It has been recognized that ZnP ₂ O ₆ produced by combustion is directly vitrified and adheres to the surface of the catalyst, thereby coating the surface of the catalyst. For the purpose of simply preventing phosphorus poisoning of exhaust gas purification catalysts, phosphorus compounds, which cause poisoning, should not be used as additives in engine oil, or if used, only in small amounts, but in reality, Phosphorus compounds as such additives are essential for engine oil performance, and it is unrealistic to say that they must be added to ensure engine oil performance. That is, engine oil is generally given a grade based on a service classification set by a public organization at the time of manufacture. This type of service classification includes various test methods and performance standard values (for example, engine rust average score, high temperature oxidation stability and valve train wear amount, sludge varnish generated during low-speed operation, average score, etc.). There are no direct regulations regarding phosphorus content, etc.). In order to clear the performance standard values mentioned above,
Zinc dithiophosphate, a phosphorus compound, is usually added as one of the additives, but oil manufacturers add more than the amount actually required by the engine to ensure that the desired grade is obtained. We are now taking appropriate measures. In other words, even if zinc dithiophosphate is added in more than a certain amount, its original anti-oxidation and anti-wear functions will be saturated;
Currently, in order to safely meet the functional standard values mentioned above, more than necessary is added. By the way, in order to prevent phosphorus poisoning of the catalyst as described above, an adsorbent such as alumina is placed upstream of the catalyst in the exhaust passage to adsorb and remove the phosphorus component contained in the exhaust gas. For example, JP-A-49
Although these are known from Japanese Utility Model Publication No. 58212 and Japanese Utility Model Publication No. 52-31870, these devices have the following problems because they are placed in the exhaust passage. That is, if the adsorbent placed upstream of the catalyst is made into pellets, the adsorbents will be worn away by each other in the exhaust gas flow, resulting in a lack of durability. There are problems such as clogging due to adhesion of unburned products to combustion products in the exhaust gas, resulting in an increase in exhaust pressure and deterioration of engine operating performance. Therefore, the basic purpose of the present invention is to remove an appropriate amount of the excessively added phosphorus compound using an adsorbent without impairing the original function of the phosphorus compound, thereby reliably preventing the deterioration of the function of the exhaust gas purification catalyst. The purpose is As a result of various experiments on the vitrification conditions of P ₂ O ₅ , the present inventors found that the vitrification of P ₂ O ₅ is a bonding target.
There is a strong correlation with the amount of ZnO, and in fact, ZnO + P ₂ O ₅
If the amount of P ₂ O ₅ is approximately 35 mol% or less,
Confirmed that it does not vitrify even at high temperatures,
Based on this confirmation, the catalyst surface is coated with a metal oxide such as ZnO that prevents the vitrification of P ₂ O ₅ , thereby reducing the relative ratio of P ₂ O ₅ on the catalyst surface to prevent phosphorus poisoning. We have already proposed a catalyst for exhaust gas purification that
59-20385). In relation to the invention of the earlier application, the present invention has the following:
By reducing the absolute amount of P ₂ O ₅ , which is the cause of vitrification, the relative ratio to vitrification-preventing metal oxides such as ZnO can be lowered to prevent P ₂ O ₅ from vitrifying even at high temperatures. In order to protect the catalyst, the phosphorus component in the engine oil is removed in advance using a practical and simple structure in the engine oil system. Therefore, in the present invention, a phosphorus adsorbent made of activated alumina that always adsorbs the phosphorus component in engine oil regardless of its chemical state is placed in the engine oil flow path. In this case, attention is paid to the fact that the adsorption performance of the phosphorus adsorbent increases as the temperature of the engine oil increases, and the phosphorus adsorbent is placed in a part where the engine oil becomes high in temperature, for example, in an oil pan. The phosphorus adsorbent according to the present invention is one in which the phosphorus adsorbent is housed in a case having liquid flowability such as a wire mesh so that engine oil can flow through the phosphorus adsorbent, and the phosphorus adsorbent includes: Activated alumina such as γ-alumina and δ-alumina, which are usually used as a carrier for exhaust gas purifying catalysts, can be advantageously used. According to the present invention, the adsorbent is placed in the engine oil flow path to adsorb and remove the phosphorus component in the engine oil. This does not cause deterioration of durability of the agent or deterioration of engine operating performance due to increase in exhaust pressure. In addition, the adsorbent placed in the engine oil flow path is used to adsorb and remove in advance the phosphorus component added to the engine oil in excess as described above. There is a limit to the adsorption capacity (phosphorus adsorption capacity per unit volume), so depending on the engine oil used, it is possible to effectively prevent phosphorus poisoning without reducing the original lubricating performance. By determining the final removal amount of phosphorus components in advance and placing activated alumina in an amount commensurate with the determined removal amount, the original lubricating performance of the engine oil is not impaired. Phosphorus poisoning can be effectively prevented. Activated alumina containing γ-alumina as a main component was used as a phosphorus adsorbent, and the results of a laboratory test of its phosphorus adsorption properties are shown in FIG. Figure 4 shows the results of a test on the temperature characteristics of activated alumina as an adsorbent. , 16.7) Adsorption members A and B in which activated alumina was surrounded by a wire mesh were prepared, and immersed in engine oil in a test tube, and the temperature of the engine oil was adjusted to 15°C, 60°C, 80°C, 100°C, It shows the change in phosphorus adsorption rate over time when kept at 120°C. As is clear from Figure 4, the phosphorus adsorption performance of activated alumina increases as the engine oil temperature increases, and therefore, the adsorbent is applied to areas where the engine oil temperature is higher than 80°C. This indicates that it is preferable to Next, FIG. 5 shows the results of an actual vehicle test conducted to determine the preferred location of the adsorption member in an actual engine oil lubrication system in relation to the engine oil temperature. By the way, as shown in FIG. 1, the engine oil lubrication system pressurizes engine oil in an oil pan 2 provided at the bottom of the engine body 1 with an oil pump 3, passes it through an oil filter 4, and then pressurizes the engine oil in an oil pan 2 provided at the bottom of the engine body 1. Most of the oil is supplied to each lubricating part in the engine body 1, and a part is supplied to the metering oil pump (not shown) provided for the carburetor (not shown). The engine oil heated to a high temperature in the oil pan 2 is returned to the oil pan 2 via a crank chamber (not shown) through a well-known system. Therefore, the temperature of engine oil is
The temperature is the highest in each lubricating section in the engine body 1, but the amount of engine oil used in this lubrication system is large, and in order to effectively remove phosphorus, a considerable amount of adsorbent is required. The location of parts is subject to space constraints. As shown in FIGS. 1, 2, and 3, FIG. 5 shows a phosphorus adsorbing member 7, which is surrounded by a wire mesh 6 serving as a case with liquid flow, and is attached to a fixing metal fitting 8. When placed at the bottom of oil pan 2
(a) When the engine is placed in the middle of the system from the oil pump 3 to the oil filter 4 (b) (not specifically shown in Figs. 1 to 3) and downstream of the oil filter 4. When placed near cooling water
The adsorption rates of (c) (Figures 1 to 3 are not specifically shown) were measured. This actual vehicle test uses a 1600 c.c. engine at 1700 r.p.m.
The test was carried out by operating at a rotational speed of pm for 24 hours, and the engine oil used was one containing 0.14% by weight of P and 0.40% by weight of Ca, as in the case of the laboratory test. Furthermore, activated alumina as an adsorbent was used in an amount of 900 c.c. (15% by volume) for 5100 c.c. of engine oil. As is clear from FIG. 5, the case (A) in which the adsorbent is placed at the bottom of the oil pan 2 exhibits the highest adsorption rate. This is because the engine oil collected in the oil pan 2 has a high temperature due to the heat of the engine, and as explained with reference to FIG. 4, the adsorption rate of activated alumina increases. Next, Table 1 shows test data on changes in the adsorption performance of activated alumina in response to oil changes in actual vehicles.

[Table] The laboratory test was conducted using the test method described in connection with FIG. 4, and the actual vehicle test was conducted using the engine and operating conditions described in connection with FIG. 5. In addition, in the actual vehicle test, the adsorbent was placed in the position (b) explained in Fig. 5, and the temperature was set at 100%.
The adsorbent was heated to maintain it at °C. *In case 1, measurements were taken after draining the entire amount of engine oil every 24 hours, flushing twice for 10 minutes, and then injecting new engine oil twice. *In case 2, the engine oil was changed once every 24 hours, and measurements were taken after repeating this 5 times. In Table 1, the numbers in brackets indicate the adsorption rate (%). What is characteristic about Table 1 is that activated alumina as an adsorbent exhibits high adsorption properties for phosphorus, whereas it hardly adsorbs calcium. This means that the Ca component that functions as a vitrification inhibitor is not removed from P ₂ O ₅ produced by combustion of engine oil, and therefore P ₂ O ₅
This means that the ratio of adsorption to vitrification-preventing metal oxides (ZnO, CaO, etc.) is much lower, indicating that activated alumina has excellent adsorption properties in two senses. Although FIGS. 1 and 2 show a lubrication system for a reciprocating engine, it goes without saying that the present invention can also be applied to a lubrication system for a rotary piston engine.

[Brief explanation of the drawing]

FIG. 1 is an explanatory vertical cross-sectional view of the engine showing the lubrication system of the engine; FIG. 2 is an exploded perspective view of the engine body showing the location of the phosphorus adsorption member according to the present invention;
Figure 3 is a longitudinal cross-sectional view of the oil pan shown in Figure 2, Figure 4 is a graph showing changes in phosphorus adsorption rate (wt%) over time at various engine oil temperatures, and Figure 5 is a graph showing changes in phosphorus adsorption rate (weight %) depending on the location of the adsorption member. It is a bar graph showing changes in phosphorus adsorption rate. 1... Engine body, 2... Oil pan, 3... Oil pump, 4... Oil filter, 7... Phosphorus adsorption member.

Claims (1)

[Claims] 1. A device for protecting a catalyst installed in an engine exhaust system, in which an adsorbent made of activated alumina is placed in an engine oil flow path to adsorb phosphorus components in the engine oil. A protection device for an exhaust gas purification catalyst, characterized in that: 2. The exhaust gas purification catalyst protection device according to claim 1, wherein the adsorbent is disposed within an oil pan. 3. The exhaust gas purification catalyst protection device according to claim 2, wherein the adsorbent is housed in a case disposed in an oil pan and having liquid flowability.