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Technical Paper

Troubles and Countermeasures on Oil Seals for Automotive Application

In order to improve the reliability of oil seals in practical use, it is considered that further basic investigation for maintaining good sealing characteristics of seals are necessary. However, the result of analysing phenomena in oil seals which has caused the oil leakage in the market shows that about 60 % of oil leakage is caused by the seal installation to housing bore or shaft, about 30 % thereof by unsuitable operating condition and remaining 10 % by the design of oil seals. From the point, oil leakage troubles and their countermeasures on oil seals for automotive application are discussed.
Technical Paper

Trouble and Countermeasure of Seals for Automotive Application —Part II

In order to improve the reliability of seals for automotive application in practical use, it is considered that further basic investigations concerning sealing characteristics of seals are necessary. However, it has been found, from analyzing seals decided in the market as defective parts, that the troubles of seals in the market are mainly caused by both wrong handling for seals and the use under wrong operating condition which has not been expected by manufacturers of seals. Therefore, in order to improve the reliability of seals, it is important to investigate in detail troubles on functional characteristics of seals and their countermeasures. In this paper, on oil seals, O-rings, water pump seals and dust cover seals as seals for automotive application, the results of investigations are discussed.
Technical Paper

The Influence of Designing Factors on the Sealing Performance of C-Seal

C-shaped metal seals (C-seal) are used as static seals under the conditions such as high vacuum, high pressure, high temperature and cryogenic states. The correlation between the sealing performance and design parameters as loading force, deformation, and the surface roughness of ontacting faces have been investigated. This paper is concerned with the relationship between the surface condition of the coated-lead layer of C-seals and the surface roughness of mating flange. The effects of surface condition on leakage are examined fundamentally. Annular coated-lead layer on the surface of a C-seal prevents leakage, though there exist the fine defects or surface irregularities on the flange. It becomes clear from the test results that the surface conditions of the flange and loading force closely relate to the leakage rates with the deflection of C-seal under the. load and the behavior of the contact condition of flange surface.
Technical Paper

The Effect of Coolant Additives and Seal Composition on Performance of Water Pump Seals of Automotive Engines

The mechanical seal in automotive water pumps is critical to the performance and reliability of the engine, requiring consistent, effective sealing performance and long operating life. In recent years, the advent of maintenance free performance requirements and increasingly severe operating conditions have resulted in significant changes to the variety and concentration of additives in cooling systems. As a consequence of these changes to the additives, various types of premature seal leakage failures have occurred during service operation. These have been categorized into four types of failure modes and compared with seals providing normal service in order to establish simulated test conditions for engine coolants containing various additives. This paper reports on the various types of failure mechanisms that were found to occur during simulated performance testing and the corrective measures that will eliminate their occurrence
Technical Paper

Study on Improvement of NOx Reduction Performance at Low Temperature Using Urea Reforming Technology in Urea SCR System

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.
Technical Paper

Study of 2-LEG NOx Storage-Reduction Catalyst System for HD Diesel Engine

A 2-LEG NOx Storage-Reduction (NSR) catalyst system is one of potential after-treatment technology to meet stringent NOx and PM emissions standards as Post New Long Term (Japanese 2009 regulation) and US'10. Concerning NOx reduction using NSR catalyst, a secondary fuel injection is necessary to make fuel-rich exhaust condition during the NOx reduction, and causes its fuel penalty. Since fuel injected in the high-temperature (∼250 degrees Celsius) exhaust instantly reacts with oxygen in common diesel exhaust, the proportion of fuel consumption to reduce the NOx stored on NSR catalyst is relatively small. A 2-LEG NSR catalyst system has the decreasing exhaust flow mechanism during NOx reduction, and the potential to improve the NOx reduction and fuel penalty. Therefore, this paper studies the 2-LEG NSR catalyst system. The after-treatment system consists of NSR catalysts, a secondary fuel injection system, flow controlled valves and a Catalyzed Diesel Particulate Filter (CDPF).
Technical Paper

Sealing Phenomena of a Lip-Type Seal for an Automotive Air Conditioning Compressor

Instead of end-face type seals, lip-type seals have recently been widely applied as sealing devices for automotive air conditioning compressors, and have shown good sealing performance in practical applications. This paper is concerned with the sealing phenomena of lip-type seals, which run under hydrodynamic lubrication between the lip/shaft surfaces.
Technical Paper

Sealing Performance of End-Face Type Seals for an Automotive Air Conditioning Compressor

End-face type seals (mechanical seals) have been applied as a sealing device for the automotive air conditioning compressor. However, in the practical market, oil or gas leakage from sealing devices sometimes occures based on blistering phenomena of carbon piece and lubricating conditions between rubbing surfaces. The paper presents good sealing performance for the developed face type mechanical seals.
Technical Paper

Numerical Study of Catalytic Reaction Mechanisms of Urea SCR

Urea-SCR(selective catalytic reduction) system is widely used as a technology of NOx(Nitrogen Oxides) reduction from diesel engine exhaust gases. Emission regulations have becoming stricter all over the world, and high NOx reduction performance is necessary to meet the emission regulations. To get higher NOx reduction performance of the Urea-SCR system, it is important to understand detailed chemical reaction mechanisms of Urea-SCR catalysts. In this study, we focused on elucidation of the reaction mechanism of the Urea-SCR catalyst by numerical simulation approach. The chemical reaction models with detail chemical reactions were built for both Fe-catalyst and Cu-catalyst. Both of the catalytic reaction models can predict difference of the catalytic reaction performance between the Fe-catalyst and the Cu-catalyst. In addition, rate-determining reaction step of the Cu-catalyst was successfully identified by the numerical simulation results.
Technical Paper

FEM Analysis of Mechanical Seals for Water Pumps of Automotive Engines

Mechanical seals have been applied as sealing devices for water pumps of automotive engines. The mechanical seal plays an important state. Therefore, there are many kinds of constructions. This paper is concerned with the FEM (Finite Element Method) analytical results for various water pump seal construction. It becomes clear that the property of heat transfer is closely related to the sealing durability.
Technical Paper

Emission Characteristics from After-Treatment System of Medium and Light Duty Engines

1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system.
Technical Paper

Effect of Surface Condition of Lip on Sealing Phenomena of Oil Seals

It becomes clear that the suction coefficient of oil, K, and the sealing characteristic constant, Φ (=fG-1/3), are closely connected with the rubbing surface state of oil seals. And, investigations have done on K-, Φ-value, etc. in oil seals after the practical use in automobiles and the results have been compared with the test results in the laboratory.
Technical Paper

Effect of Quantity of Lubricating Oil on Sealing Characteristics of Oil 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.
Technical Paper

Effect of Foreign Matters on Sealing Characteristics of Oil Seals

Fine solid particles in a lubricating oil affect the sealing characteristics of oil seals, and their lives are shortened by the wear of oil seals and shafts created by the particles. Tests were carried out by using various kinds of foreign matters. The results showed that foreign matters in oil film between the sealing lip and the shaft surface directly caused the leakage. Consequently, it was reconfirmed that the practical application of dust lip and the countermeasure in the construction of seals or their housings were indispensable to obtain the long life and the stable operation of oil seals.
Technical Paper

Development of a Low Frictional Mechanical Seal for Turbocharger of Automotive Engines

The turbo-charger of an automotive engine is commonly used for increasing its power characteristics. In this equipment, both sealing and lubricating conditions are important factors and face to difficult technical problems. This paper is concerned with sealing problem for the turbo-charger, and development of low frictional type mechanical seals with good performance and excellent reliability.
Technical Paper

Development of New Type Oil Seal for Automotive Application

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.
Technical Paper

Development of New Diesel Particulate Active Reduction System for both NOx and PM Reduction

The new Diesel Particulate active Reduction (DPR) system was developed for a medium-duty commercial vehicle as a deNOx catalyst combined with the conventional DPR system to achieve the Japan Post New-Long-Term (JPNLT) emissions regulations. It consists of a catalyst converter named as the new DPR cleaner, a fuel dosing injector, NOx sensors, temperatures and pressure sensors. The new DPR cleaner was constructed from a Front Diesel Oxidation Catalyst (F-DOC), a catalyzed particulate Filter (Filter), and a Rear Diesel Oxidation Catalyst (R-DOC). A newly developed Hydrocarbon Selective Catalyst Reduction (HC-SCR) catalyst was employed for each catalyst aiming to reduce NOx emissions with diesel fuel supplied from the fuel dosing injector. While the total volume of the catalyst was increased, the compact and easy-to-install catalyst converter was realized through the optimization of the flow vector and flow distribution in it by means of Computational Fluid Dynamics (CFD) analysis.
Technical Paper

Development of Low Friction Oil Seals for Automobiles

Improvement of automotive fuel consumption is subject of saving energy today. Oil seals with low friction for automobile are required in the market. In this report, an idea for decreasing the friction of seals and its concreate countermeasure are discussed. It becomes clear that developed low friction seals have good sealing performance as same as present seals.
Technical Paper

Comments on Oil Seals for Engine Applications in Small Size Japanese Passenger Cars

According to the 1982 Japanese Engine Data Book, 249 automobile engine models are used, including gasoline and diesel engines. Among them, 87 models (approximately 60% of all 4-cycle gasoline engine models), are designed for small passenger car applications, with displacements between 1.51 and 2.00. This paper will highlight the area such as Seals for Automobile Engine Applications, Present Automotive Engine Seal Situation in Japan and Countermeasure Activity for Field Claims.