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To reduce NOx and PM emissions in exhaust gas, after-treatment systems for low NOx emissions are being developed in combination with improvements of engine combustion. In recent years, the exhaust gas temperature has been dropping because of enhanced low-fuel consumption of the engine. Therefore, it is urgent to develop NOx reduction technologies that work at a low temperature under 200degC. Since NOx is reduced by reacting with ammonia supplied to the SCR catalyst, it is necessary to make the urea solution decompose into ammonia using the heat of the exhaust gas to supply sufficient ammonia to the SCR catalyst. However, both the decomposition reaction and hydrolysis reaction of the urea have insufficient exhaust heat, thus making it difficult for urea to decompose and hydrolyze to ammonia at a low temperature. To solve this problem, it focuses on forcibly decomposing the urea solution without depending on the exhaust gas temperature.

Mechanical seals have been applied as a sealing device for an automotive air conditioning compressor. Sometimes, the leaking trouble occurs under the conditions such as excessive wear, blistering formation and cracking phenomena on the carbon-ring. This paper is concerned with the analysis of cracking phenomena based upon Finite Element Method (FEM) calculation and experimental investigation.

Mechanical seals have been applied as a sealing device for an automotive air conditioning compressor. However, the leaking trouble occurs under the conditions such as excessive wear, blistering formation and cracking phenomena on the carbon-rings. This paper is concerned with a study of carbon-cracking phenomena.

End-face type seals have been applied as sealing devices for the water pumps in the cooling systems of automotive engines. However, many troublesome problems have occurred for many years and the countermeasures have been investigated as many times. For examples, the problem of excessive abrasion of seal faces caused by foreign particles in liquid to be sealed was solved by using the sliding materials which had a hither thermal conductivity and a lower coefficient of thermal expansion. Furthermore, the noise problem of the ringing phenomena caused by the stick-slip between sliding surfaces was prevented by changing the carbon material whose lubrication characteristics had a negative slope as weak as possible in the Torque-Speed curve. As a result of these investigations, end face seals of this type have obtained the satisfactory sealing performance for many users' requirements in the present Japanese market.

It is clear that excessive lip wear is one of the origin of oil seal leakage in the market. In this paper, follows are discussed; Oil seals used for the rear side of automotive mission gear case have excessive lip wear as typical failure mode, and the sealing characteristics of oil seals is influenced by reciprocating motion of rotational shaft with rough surface.

New type oil seals - nonwoven fabric secondary lip type oil seals are recently widely used for one of the sealing apparatus for automotive application. Basic improvement of this type of seals is in a secondary lip which prevents solid foreign matters such as dust and sand from entering into the rubbing portion between a primary lip of oil seals and a shaft. This secondary lip is superior in anti-dust property, wear resistance, following ability to the shaft eccentricity and air permeability to the conventional secondary lip of rubber. And the sealing performance of new type seals with the secondary lip made of special nonwoven fabrics is more stable than that of the conventional rubber seals.

For purpose of clarifying the effect of quantity of lubricating oil supplied to the seal lip portion on sealing characteristics of oil seals, relations between the typical constructional applications of the fitting portion for oil seals and the quantity of the lubricating oil supplied to the oil seals are discussed. Then the necessary minimum quantity of the lubricating oil for preventing the seal lip from wear is investigated. And it is clarified that the decrease in sealing characteristics occurs when the lubricating oil is supplied insufficiently to the seal lip portion and, finally, the countermeasure is discussed.

It is well known that the low-temperature test is successful for rating sealing characteristics of oil seals. Therefore, a compound with good thermal resistance to an ambient temperature range from -40 to +150°C is needed by the oil seal industry and should be developed. On the other hand, it is indicated that low temperature affects the sealing characteristics and the lip abrasion of oil seals. This paper examines the relation between temperature and the sealing characteristics of oil seals. It is clear that the condition of the rubbing surface is closely related to the sealing characteristics of oil seals, and that the lower the ambient temperature falls, the rougher their rubbing surfaces become. Moreover, the roughening condition of the rubbing surface is intimately related with the environmental temperature, the rubbing period, the lubricating condition, the lip design, and compounds.