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Recently, emission regulations have been strict in many countries, and it is very difficult technical issue to reduce emissions of diesel cars. In order to reduce the emissions, various combustion technologies such as Massive EGR, PCCI, Rich combustion, etc. have been researched. The combustion technologies require precise control of the states of in-cylinder gas (air mass flow, EGR rate etc.). However, a conventional controller such as PID controller could not provide sufficient control accuracy of the states of in-cylinder gas because the air-pass system controlled by an EGR valve, a throttle valve, a variable nozzle turbo, etc. is a multi-input, multi-output (MIMO) coupled system. Model predictive control (MPC) is well known as the advanced MIMO control method for industrial process. Generally, the sampling period of industrial process is rather long so there is enough time to carry out the optimization calculation for MPC.

An electric servo brake system applied for use on electric vehicles was applied for use on plug-in hybrid vehicles in order to achieve fuel-savings together with good brake feel and enhanced operability for plug-in hybrid vehicles. The electric servo brake system is made up of highly accurate braking pressure control that functions cooperatively with regenerative brakes together with a structure in which pedal force is not influenced by braking pressure control. The configuration of these components enabled good braking feel even when the power train was being switched from one drive mode to another. Automated pressurization functions that are intended for plug-in hybrid vehicles and that operate with electric servo brake systems were also developed. These developed functions include stall cooperative control that functions cooperatively with the power train, regenerative coordinate adaptive cruise control, and hill-start assist.

The Honda variable valve timing and lift electronic control system (VTEC) is incorporated in the engine of the NSX sports car that is scheduled for sales in Europe this year. In the process of advancement of Honda's engine technology, VTEC was developed for much higher output and higher efficiency. This is actually the first system in the world that can simultaneously switch the timing and lift of the intake and exhaust valves. This system has made improvements in maximum output at high rpm, and also improved the low rpm range, such as idling stability and starting capability.

The purpose of this research was to predict the amount of wear on exhaust valve seats in durability testing of gasoline engines. Through the rig wear test, a prediction formula was constructed with multiple factors as variables. In the rig test, the wear rate was measured in some cases where a number of factors of valve seat wear were within a certain range. Through these tests, sensitivity for each factor was determined from the measured wear data, and then a prediction formula for calculating the amount of wear was constructed with high sensitivity factors. Combining the wear amount calculation formula with the operation mode of the actual engine, the wear amount in that mode can be calculated. The calculated wear amount showed a high correlation with the wear amount measured in bench tests and the wear amount measured in vehicle tests.

A continuously variable valve lift gasoline engine can improve fuel consumption by reducing pumping loss and increase maximum torque by optimizing valve lift and cam phase according to engine speed. In this research, a new control system to simultaneously ensure good driveability and low emissions was developed for this low fuel consumption, high power engine. New suction air management through a master-slave control made it possible to achieve low fuel consumption and good driveability. To regulate the idle speed, a new controller featuring a two-degree-of-freedom sliding-mode algorithm with cooperative control was designed. This controller can improve the stability of idle speed and achieve the idle operation with a lower engine speed. To reduce emissions during cold start condition, an ignition timing control was developed that combine I-P control with a sliding mode control algorithm.

Honda R&D has developed a throttle-by-wire (TBW) system that meets the needs of motorcycles where the attitude of the vehicle body is controlled by operation of the throttle. To gain high response and following for the throttle valve, we employed a new adaptive control algorithm. The newly developed system has an idling combustion stabilization function and a three-dimensional control function for the throttle-opening map based on running gear and engine speed. With those functions, we improved the controllability of the motorcycle, especially for small throttle openings. Furthermore, we improved the feeling of the limiter control used in maximum-speed limitation. For the overall system, intake system related devices are consolidated to improve the layout flexibility and expand the mounting options on the motorcycle.

The new automatic transmission, A-HMT (Advanced Hydro-Mechanical Transmission) has been developed for the Honda ATV (All Terrain Vehicle), which is for wide applications such as utility, recreation, etc. The A-HMT system features high performance, durability and reliability attained by improving the structures from the original hydro-mechanical automatic transmission used for the scooter called “Juno”, which Honda had produced many years ago, working on the same principle. In addition to it, by applying the electronic control system, the highly responsive driveability that suits the requirements of ATV's has been realized. The A-HMT is installed in the new 500 cm3 ATV, FOURTRAX FOREMAN RUBICON, which has been introduced in the USA market since June 2000.

Variable-valve-actuation mechanism is considered to be one of the most suitable solutions to realize the compatibility between higher power output and performances in the practical speed range. A new variable-valve-actuation mechanism named “Shuttle Cam” was designed and studied. In this mechanism which was applied to a conventional motorcycle engine with rocker arms and gear-train-driven valve system, the cam gears move along the idler gear. And cam shafts simultaneously slide along the rocker-arm slipper surfaces which are concentric with the idler gear. Consequently valve lift varies continuously in accordance with the alteration in the rocker-arm lever ratio and the cam phasing changes simultaneously in accordance with the cam gear rotation. Result of the experiments has confirmed that the mechanism functions accurately even at high speeds up to 10,000 rpm and some improvements were achieved in power output, fuel consumption, idling quality, and exhaust-noise level.

A measurement method for valve behavior during engine firing is established. In order to grasp valve behavior accurately, it has been required to develop a measurement method for valve behavior that takes in account for the condition during engine firing. However, behaviors of a valve train have generally been analyzed during engine motoring because it is difficult to measure them during engine firing. In this study, valve behavior during engine firing can be measured accurately by attaching a gap sensor to the valve guide. Furthermore, the simulation system for valve behavior that treated the valve train as three-dimensional flexible body is built. Under engine motoring condition, high correlation between measurement and simulation is confirmed for valve behavior and spring stress.

To comply with the environmental demands for CO2 reduction without compromising driving performance, a new 1.0 liter I3 turbocharged gasoline direct injection engine has been developed. This engine is the smallest product in the new Honda VTEC TURBO engine series (1), and it is intended to be used in small to medium-sized passenger car category vehicles, enhancing both fuel economy through downsizing, state-of-the-art friction reduction technologies such as electrically controlled variable displacement oil pump and timing belt in oil system, and also driving performance through turbocharging with an electrically controlled waste gate. This developed engine has many features in common with other VTEC TURBO engines such as the 1.5 liter I4 turbocharged engine (2) (3), which has been introduced already into the market.

An electric powertrain has been developed for Honda’s 2017 model hybrid SUV. The electric powertrain developed for the hybrid model consists of a Twin Motor Unit (TMU), a high-output front motor mated to a 7-speed DCT for efficient power generation, a Power Control Unit (PCU), and an Intelligent Power Unit (IPU). The TMU is made up of two motor units able to drive the left and right wheels independently, as employed in Honda’s flagship sedan and high-end sports cars. The PCU delivers electric power to the motors, and the IPU stores drive torque and regenerative energy. The high-output front motor and TMU are equipped with sports hybrid SH-AWD components, as used in existing mass-production models, in order to realize handling performance equaling that of the base SUV. Positioned under the floor outside the passenger cabin, the PCU has a newly developed 3-in-1 inverter, motor control ECU, and 12V DC-DC converter built-in, and is housed in a fully waterproof structure.

A new electric power steering (EPS) was developed which uses an electric motor to provide assistance. It is a system combinning the latest in power electronics and high power motor technologies. The development was aimed at enhancing the existing hydraulic power steering's energy efficiency, driver comfort as well as increasing active stability. This paper describies the overall concept of EPS and outlines the components and control strategies using electronics. The EPS was tested on a front wheel drive vehicle weighing 1000kg in front axle load. The results showed a 5.5% improvement in fuel economy. The EPS has also achieved returnability that gives the driver more moderate feelings matching the vehicle in action as well as the active stability control strategy for high speed driving.

Honda developed a 750cm3 V-4 engine adopting an elliptical piston, and began selling the “NR” motorcycle with the engine installed in 1992. The adoption of an elliptical piston and cylinder achieved a compact layout of eight valves, which consists of four intake valves and four exhaust valves per cylinder. This paper explains the features of an engine with such a layout, focusing on the following: 1) Multiple valves and short-stroke enable the 750cm3 engine to achieve 15,000rpm. 2) The engine is more compact and lightweight than an engine having the same displacement, and more powerful than one with twice as many cylinders (8 cylinders). Also, this paper describes the techniques giving improved blowby gas and oil consumption characteristics as related to the sealing property of the piston, cylinder and piston ring and achieving performance equivalent to a conventional motorcycle engine.

To enable non-throttling operation of gasoline S.I. engine, we have manufactured engines equipped with a newly developed Hydraulic Variable-valve Train (HVT), which can vary its intake-valve closing-timing freely. The air-intake control ability of HVT engine is equivalent to conventional throttling engines. Combustion becomes unstable, however, under non-throttling operation at idling. For the countermeasure, newly designed combustion chamber has been developed. The reduction of pumping loss by the HVT depends on engine speed rather than load, and amounts to about 80 % maximum. A conventional engine-management system is not applicable for non-throttling operation. Therefore, new management system has been developed for load control.

Recently, much research has been carried out on secondary O2 feedback which performs control based on the output from a secondary O2 sensor (HEGO sensor). In this research it has been found that, regardless of catalyst aging conditions, the HEGO sensor output indicates 0.6 V when the catalyst reduction rate is maintained at the optimum level. Therefore, based on this relationship, we designed an accurate secondary O2 feedback with the aim of reducing emissions by stabilizing the HEGO sensor output to 0.6 V. In order to realize this control, it was necessary to solve the three problems of nonlinear catalyst characteristics, dead time characteristics, and changes in dynamic characteristics due to catalyst aging conditions. Therefore, these problems were solved using the modeling approach of robust control and a new robust adaptive control named Prediction and Identification Type Sliding Mode Control.

New valve control system (HYPER VTEC:Variable Valve Timing and Lift Electronic Control System) having valve inactive mechanism which engine power is made to be united to the environment conservation was developed for motorcycle engines of sport type having higher engine speed. Mass increase in the valve operating system of this system is kept to a minimum with a compact, simple mechanism. The system enables high engine speed up to 13,500 rpm without abnormal motion of valves, having high reliability and durability. In addition, the valve control system has the enhancement of fuel economy and the effect of decreasing the intake and exhaust system sound during 2-valve operation. The switching mechanism part of the operating valve number was manufactured by cold forging, and has decreased costs. This system has been adopted to the sport type motorcycle CB400SF for domestic model in 1999.

Owing to its combustion characteristics and chemical composition, natural gas features cleaner emissions and lower CO2 compared to gasoline under equal thermal efficiency. Natural gas can be a promising alternative energy source to respond to crude oil exhaustion and global warming issues. Focusing on the utility of natural gas, a feasibility study on CNG (Compressed Natural Gas) -fueled two-wheeled vehicles has been conducted. A proto-type two-wheeled vehicle was made based on a 125 cm3 class gasoline-fueled scooter. To adapt the engine to the use of CNG fuel, an electronically controlled gas injection system was applied to the fuel supply system. To provide abrasion resistance of engine valves and valve seats, the specific matter of gas-fuel was improved. Furthermore, a lubricant circulation passage was added to maintain the temperature of the pressure reducing valve.

Early activation of catalyst by quickly raising the temperature of the catalyst is effective in reducing exhaust gas during cold starts. One such technique of early activation of the catalyst by raising the exhaust temperature through substantial retardation of the ignition timing is well known. The present research focuses on the realization of quick warm-up of the catalyst by using a method in which the engine is fed with a large volume of air by feedforward control and the engine speed is controlled by retarding the ignition timing. In addition, an intake air flow control method that comprises a flow rate correction using an adaptive sliding mode controller and learning of flow rate correction coefficient has been devised to prevent control degradation because of variation in the flow rate or aging of the air device. The paper describes the methods and techniques involed in the implementation of a quick warm-up system with improved adaptability.