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Technical Paper

Development of Coordinated Algorithm of EGR and Boost Pressure based on the Adaptive Sliding Mode Control

In case of the turbocharged engine, it is difficult to control both the air mass flow and the EGR flow. Because the air mass flow and the Exhaust Gas Recirculation (EGR) flow are influenced by the boost pressure, it becomes necessary to manipulate the many inputs to control them. Therefore, to overcome this problem, we developed the new Multi Input Multi Output (MIMO) algorithm based on the adaptive sliding mode control (SMC) which eliminated the observer. And consequently, it is confirmed that this new algorithm makes it possible to track both the air mass flow and EGR flow to the desired value.
Technical Paper

Analysis of Mixture Formation Process in a Stoichiometric Direct Injection Gasoline Engine

The stoichiometric direct injection gasoline engines have higher torque performance than the port injection engines, as the volumetric efficiency can be increased due to the cooling effects of charging air by the fuel evaporation in the cylinder. They need only 3-way catalyst, leading to the cost down. However there exists the injection timing (region) that increased volumetric efficiency does not lead to higher torque. In order to investigate the phenomena, the in-cylinder mixture formation process has been analyzed by the LIF and the CFD techniques. As the results, it has been revealed that the phenomena are caused by the inhomogeneous mixture distribution before the ignition timing.
Technical Paper

Research on the Co-free Intelligent Catalyst

We have already reported that a LaFeCoPdO3 perovskite catalyst has the function for self-regeneration of Pd [1, 2, 3, 4, 5 and 6]. But cobalt was recognized as an environmental burden. In order to prepare for its practical application, we examined the composition of perovskite without cobalt. In this paper, we have investigated the catalytic activity, the structural durability and the regenerative ability of Co-free perovskites LaFePdO3, in comparison with LaFeCoPdO3 and Pd/Al2O3. As a result, the structural durability of LaFePdO3 is high, and the light-off performance is excellent even after aging. “Co-free Intelligent Catalyst” is regarded as the next technology for practical use especially as it is efficient in the reduction of emissions at cold starting.
Technical Paper

Regeneration of Precious Metals in Various Designed Intelligent Perovskite Catalysts

We have reported the innovation of “An Intelligent Catalyst” which has the function for self-regeneration of Pd realized through the solid solution and segregation of Pd in a perovskite crystal. In this study, we did further research on regeneration for three different precious metals (Rh, Pd and Pt) in two types of perovskite systems (LaCeFeO3 and LaCeCoO3). In perovskite catalysts loaded with precious metals, the durability of the perovskite structure in redox fluctuation at high temperature is indispensable to suppression of the grain growth of precious metals. The key technology for the development of intelligent catalysts is considered to be the affinity of precious metals to durable perovskite oxides. In the six kinds of perovskite catalysts investigated here, only the Pd loaded LaCeFeO3 catalyst was considered “intelligent”.
Technical Paper

A Hexa-Aluminate Automotive Three-Way Catalyst

With emission regulations getting tighter and tighter, catalysts will need to be active at ever lower temperatures in order to meet future standards. To meet this need, automotive catalysts are being installed closer to the engine so as to be active immediately after start-up. In this location, catalysts must have high temperature durability. In this paper, we examined a heat-resistant support material, “hexa-aluminate”, for possible use in future automotive catalysts. Catalytic activity of hexa-aluminate was more better than La added γ - alumina after redox treatment in model gas and after engine aging. Since hexa-aluminate had the excellent thermal durability, and Pd, which are supported on it, maintains finer particles than those on La added γ-alumina. We suggest that hexa-aluminate is a effective support material for automotive catalysts. More specifically, hexa-aluminate is expected to be a key technology for meeting the stringent emission standards of the future.
Technical Paper

An Intelligent Catalyst

The catalyst of the crystalline ceramics known as a perovskite-type oxide was designed and controlled at the atomic level in order to create a new function for self-regeneration of precious metals in a usage ambience without auxiliary treatment. We have already reported that a catalyst with Pd supported on the perovskite-type oxide has higher activity than a catalyst with Pd supported on alumina. It was also found that Pd supported on the perovskite catalyst is finely dispersed [1, 2 and 3] The object of this study was to investigate the mechanism of self-regeneration by using hyper-analytical facilities. XAFS analysis, at SPring-8 (8 GeV), revealed that Pd is in six-fold coordinations with oxygen in a perovskite crystal, which indicating that Pd occupies the B site of the unit formula of ABO3 in the perovskite crystal structure under oxidation atmosphere.
Technical Paper

Influence of Oxygen Storage Characteristics on Automobile Emissions

The catalytic performance and On-Board Diagnostics (OBD) of the manifold catalyst having high Oxygen Storage Capacity (OSC) are described in this paper. First of all, we compared the performance of three-way catalysts containing Cerium - Zirconium - Yttrium oxide with Cerium - Zirconium oxide. Three-way catalysts dispersed Pt, Rh and Pd on Cerium - Zirconium - Yttrium oxide showed excellent catalytic performance especially at cold starting and at transient states, after high temperature aging at 1050°C. The performance of these catalysts was studied using the Driving Mode Simulation Dynamometer, which was developed in-house, and oxygen storage and release responses were compared in actual gas. Then we investigated the possibility of on-board diagnostics of catalyst deactivation with high OSC in manifold and close-coupled positions, a diagnostic which is usually assumed to be difficult to attain with present conventional technology.
Technical Paper

Influence of Support Materials on Durability of Palladium in Three-Way Catalyst

In this paper, we studied the influence of support materials on Pd in three-way catalysts for the aim of enhancing the durability of Pd, particularly CO and NOx conversion efficiencies which are usually seriously damaged after aging. Since the durability of precious metals was found to be strongly influenced by the support material chosen, it should be possible to optimize catalyst performance by finding the appropriate support. The performance of Pd three-way catalysts with different support materials (Aluminum oxide, Cerium - Zirconium Oxide, Cerium - Zirconium -Yttrium Oxide, Zirconium Oxide, or Titanium Oxide) was compared after high temperature agings under various gas conditions. To assess Pd deterioration, the crystallite size of Pd was measured with XRD and the micro surface was observed by FE-SEM. The performance of the catalysts was evaluated.
Technical Paper

Oxygen Storage Capacity on Cerium Oxide - Precious Metal System

Cerium oxide (CeO2) is known to have good oxygen storage capacity (OSC) and is used widely in three-way catalysts for automobiles, but it has a problem of inferior heat stability. In our previous work, cerium-zirconiumyttrium (Ce Zr-Y) oxide systems were investigated with the aim of improving the heat stability of CeO2-based oxide systems, and we found an optimum composition of Ce-Zr-Y oxide with platinum (Pt) showed good OSC even after high temperature aging. In this study OSC and thermal stability of Ce-Zr-Y oxide with varying the types of precious metals were investigated to evaluate the effect of precious metals. The results show that, Palladium (Pd) and Rhodium (Rh) are also available for Ce-Zr-Y oxide with precious metal system to improve OSC after thermal aging. In particular, Rh exhibited higher improvement than others at the composition of lower Ce content.
Technical Paper

Improvement in Oxygen Storage Capacity

Cerium oxide (Ceria) is known to have good oxygen storage capacity (OSC) and is used widely in three-way catalysts for automobiles, but it has a problem of heat stability since it is less stable than aluminium oxide (Alumina). In the present work, cerium-zirconiumyttrium (Ce-Zr-Y) oxide systems were investigated with the aim of improving the heat stability of CeO2-based oxide systems, which would result in great improvement in OSC. We found an optimum composition of Ce-Zr-Y oxide with platinum (Pt) dispersed in it at a quantity of 0.1 % in weight, which showed good OSC starting from 100°C upwards even after thermal aging at 1000°C for 2 hours under variable atmospheric conditions of rich-lean fluctuations.
Technical Paper

Durability of Three-Way Catalysts with Precious Metals Loaded on Different Location

It is necessary to mount a three-way catalyst at a place near the engine such as a close coupled converter or manifold converter to decrease cold-start emission. Naturally, in that case the catalyst of course is used under considerable A/F fluctuations at higher temperatures. We have developed a catalyst with excellent durability under such severe conditions. Three types of catalysts, made with different loading locations of precious metals, were evaluated using model gases. Durability was found to strongly depend on the loading location, and thus it should be possible to design an optimal catalyst for close coupled and manifold converters.
Technical Paper

Excellent Oxygen Storage Capacity of Perovskite-PD Three way Catalysts

Increasingly stringent emissions controls have led to a greater emphasis on strategies designed to minimize emission during cold start. One strategy employed is that of close-coupling the catalyst to the exhaust manifold of the engine in an effort to minimize catalyst light-off time. In this configuration, the catalyst must exhibit a high degree of thermal stability. Further, since the catalyst is situated nearer to the engine, it is more liable to sense cylinder-to-cylinder variations in exhaust gas composition and thus needs to possess a wider operating window than a catalyst positioned further underbody. We have previously reported that Perovskite-Pd catalysts exhibit excellent heat resistance and have three-way catalyst activity comparable with or superior to that of Pt-Rh/ Al2O3 catalysts and Pd/Al2O3 catalysts [1]*. Durability at high temperatures and oxygen storage capacity under large air/fuel (A/F) ratio fluctuation conditions have now been tested.
Technical Paper

Perovskite-Pd Three-Way Catalysts for Automotive Applications

Three-way catalysts which remove different kinds of pollutants, such as CO, THC(total hydro-carbon) and NOx, simultaneously from the automotive exhaust gas employ Rhodium(Rh) in combination with Platinum(Pt) and Palladium(Pd). Rh is the most effective for reducing NOx to N2, but Rh is the most expensive of these precious metals. The ratio of Rh to Pt applied for automobiles frequently exceeds the natural production. The gap between supply and demand of Rh sometimes causes the big price fluctuation. Accordingly, many attempts to reduce the amount of Rh loaded or to develop non-Rh three-way catalysts have been made. Although Pd catalysts are considered to be promising candidates for non-Rh automotive three-way catalysts, some performance are still inferior to Pt-Rh catalysts. We have found that an excellent three-way catalytic activity appears by compounding new Perovskite-structured oxides with Pd and auxiliary oxides.