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The effects of cross section shape of the seal, rubber material property and their combination on the friction force of reciprocating seals were investigated. O-ring, D-ring and Oval-ring were prepared as different cross section shape of the reciprocating seal. In particular, D-ring and Oval-ring were designed to be narrow width to save the space. The seals were made from rubber material with different mechanical property and low temperature property. The friction forces of the seals were measured at −40 to 150°C. The O-ring made from rubber material with lower rubber hardness and lower TR10 reduced the friction force. The friction force of Oval-ring was decreased in comparison with those of O-ring and D-ring. The decrease in the friction force was caused by leaning in the groove. The combination of Oval-ring and rubber material property reduced the friction force of the reciprocating seal. The seal was reciprocated for 1 million cycles as a durability test.

In developing engine oils, it is crucial to consider their compatibility with the rubbers used for seals. Among the different seal rubbers, silicone rubber is particularly susceptible to attack by acids and bases, which means it would be more likely to be affected by certain engine oil additives. In this study, the effects of some major additives, namely detergents, zinc dialkyl-dithiophopshate (ZDDP) and molybdenum dithiocarbamate (MoDTC), on silicone rubber were investigated. Silicone rubber test specimens were immersed in sample oils containing these additives for a prescribed period at 150°C, then the physical properties of the test specimens were measured to compare the effects of the different additives. It was found that ZDDPs dramatically reduce the tensile strength of silicone rubber, with primary ZDDP having a greater effect than secondary ZDDP.

Unexpected noise may occur around air intake manifold when the throttle valve is quickly opened. In order to solve this problem, mesh is often mounted into the air flow between the intake manifold and the throttle body. In this study the effect of mesh design on the noise reduction was investigated. Several designs of the mesh were tested with an actual automobile and the developed test equipment taking advantage of an intake manifold unit, and the noise attenuation was discussed with measuring the noise and observation of the mesh deformation. Based on those experiments, the mesh design for noise reduction was optimized. Furthermore integration of mesh and rubber gasket was examined. Finally, rubber mesh-gaskets which provide sealing and noise attenuation for air intake has been proposed in this study.

Several number of ball joints are used in the suspension system. For these ball joints, rubber dust covers are used in order to maintain sufficient lubrication and protect the ball joint from contaminants such as water and dusts. In recent years, the number of breakage or grease leakage of the dust cover used under ultralow temperature is increasing with the growth of automobile selling in developing countries. In this research, we have studied the mechanism of dust cover breakage under ultralow temperature by focusing on the low temperature behavior of a rubber material.

SOFT METAL (SUS plate coated with rubber) is used for cylinder head gasket (CHG). Conventionally, this SUS plate is preprocessed using coating chromate. When this was changed to chrome-free agent, the rubber was peeled off from the plate. There are found that this may be due to the electrochemical reaction caused by the contact between different metals-Al of the engine block and Fe (SUS) of CHG.

This paper addresses the temperature dependence of friction properties in seals (O-rings and D-rings) for use in reciprocating motions. The narrower focus here is on several factors: the effects of a lubrication state, the change in dimension and the physical properties of a rubber material. It can be assumed that they influence the temperature dependence of a frictional force. As shown in this study, A frictional force has a profile characterized by temperatures. It is revealed that the profile of a frictional force is mainly attributable to the deformation of a rubber material in motion-the physical properties (elastic modulus) of a rubber materials-and the rate of recovery in elasticity of a rubber material. In addition, a temperature showing the maximum frictional force is largely attributable to the low-temperature properties of a rubber material. It is revealed that the temperature dependence of a frictional force is mainly influenced by the material properties of rubber.

Leakage occurs between contact surfaces due to the surface roughness. In general, soft materials such as rubber are used to perform a sealing function. Softmetal used as an engine seal material, is a stainless steel plate coated with rubber. In order to seal a fluid, it is necessary to design the rubber coating and the contact pressure with consideration of the surface roughness. In this study, leak tests are conducted with the softmetal, and the effects of contact conditions, such as surface roughness, load, rubber thickness and rubber material are investigated. A differential pressure system using nitrogen gas was constructed for the leak test, and a surface of anisotropic roughness is adopted. The size of the clearance due to the geometrical shape of surface asperities is calculated from an indentation test. A model of rubber compliance to surface asperities is proposed, which predicts the sealing contact pressure with the rubber thickness.

Lubricants such as wax and grease are used to improve adhesion, frictional properties, and sliding noise of thermoplastic elastomer (hereafter referred to as TPE) products used for automotive parts. These lubricants help improve the lubrication of products when added to TPE products or applied directly to the surface. Long-term effectiveness can be expected from the former method due to the gradual movement of the lubricant from the inside to the surface. Clarifying this transfer phenomenon should therefore be very important for predicting and controlling product characteristics. This paper reports on an analysis method applying infrared spectroscopy developed by the authors, and investigations conducted on the surface transfer of lubricants such as wax and grease for polyester TPE used for CVJ boots.

In this study, we studied the phenomenon of compression cracks generated in the use of perfluoro rubber (FFKM) O-rings at high compression ratios and high temperatures, and clarified the correlation between elongation at break, thermal expansion coefficient, and internal strains and cracks obtained using FEM analysis. The results showed that the smaller the thermal expansion coefficient and larger the elongation after fracture in the material, the smaller will be the internal strain, and less easily will cracks occur. In order to prevent compression cracks under high temperatures, there is a need to design materials with small thermal expansion coefficient and large elongation at break.

This paper reports on a new concept for static seal designs taking into consideration the surface roughness of sealing surfaces. The concept focuses on fluid penetration from the interstices between the seal and counterface caused by surface roughness. In the study, we investigated the relation between the leakage and surface roughness of the sealing surface of the elastomer seal. At the same time, we also analyzed the contact state of the elastomer seal based on the equations of Ishiwata et al. on deformation of elastomer surface into rough surfaces [1]. The micro-leakage testing machine (SMLA) developed by the authors was used to measure micro-leakage at high precision and in a short time [2]. The results showed that the sealing phenomena were related to the ratio of seal surface contact pressure Ps / elastic modulus of seal E, determined by the compression ratio of seals, and does not depend on the chemical structure and hardness of the elastomer used.