Abstract: An after-burner heated catalyst control system and associated control circuit for controlling operation of an after-burner heated catalyst. The control circuit has an air pump motor, a spark plug, and a fuel injector, while the catalyst is disposed within an exhaust passageway of the engine. The control circuit further includes an apparatus for controlling operation of and pulse wave modulating the air pump motor, one spark plug, and fuel injector. An RS232 interface is provided for transmitting and receiving data from and to the control circuit. In addition a method is provided for controlling a temperature of an after-burner heated catalyst and adjusting adaptively the pulse wave modulation of the air pump motor, spark plug, and fuel injector.

Abstract: The exhaust emission containing large and small particles, discharged from an exhaust port of a cylinder No. 1 of an engine during a first exhaust stroke collides with a first adsorbent opposed to the exhaust port, so that some of the small particles of HC enter a connecting gas passage. Since the latter is not connected to a second adsorbent for a cylinder No. 3 in which a second exhaust stroke consecutively occurs, the exhaust gas discharged from the first cylinder can be easily introduced in the first adsorbent and in the connecting gas passage. When the cylinder No. 4 changes to an exhaust stroke, the exhaust gas discharged therefrom is introduced in the connecting gas passage through the corresponding adsorbent to move the HC remaining in the connecting gas passage toward the first adsorbent. Thus, the HC is adsorbed again by the first adsorbent and little is discharged into the air. Consequently, the HC adsorbing efficiency can be enhanced.

Abstract: A fuel injection control method controls the air-fuel ratio of the air-fuel mixture to be supplied to an internal-combustion engine provided in its exhaust system with an NOx reducing catalytic converter so that the NOx reducing catalytic converter is able to give full play to its ability. A first air-fuel mixture of a stoichiometric or a fuel-rich air-fuel ratio and a second air-fuel mixture of a lean-fuel air-fuel ratio are supplied alternately for predetermined time intervals respectively.

Abstract: A modified in-line adsorber system capable of meeting the California ultra-low emission vehicle (REV) standard using a combination of burn-off catalyst and a modified adsorber constructed with an open flow region of substantially unobstructed flow having a hole or a region of larger cell openings to increase the amount and rate of contact between the exhaust gas and the burn-off catalyst, and thereby reduce the light-off time of the burn-off catalyst. For best effect, the open flow region of the adsorber is positioned along the exhaust stream between the engine and the burn-off catalyst as defined by the exhaust flow path of least resistance.

Abstract: An ionization unit is placed in an engine exhaust system. The ionization unit comprises an inlet to a first chamber and an outlet from a second chamber. Within the first chamber there is located an anode mesh and a grid mesh adapted to place a negative charge upon particulate matter passing through the first chamber. Within the second chamber there is located an anode element positively charged to attract the negatively charged particulate matter. Relatively clean air is exhausted at the outlet.

Abstract: An exhaust manifold of which each exhaust port is formed by a pipe member is disclosed. Each pipe member at one end portion has a wedge shape section. Each pipe member at the other end portion is connected to the cylinder head of an engine. The pipe members are abutted one another in the one end portion to form the merging portion of the exhaust manifold. A plurality of radial partition walls are formed in the merging portion by joining end surfaces of the pipe members one another. In the exhaust manifold, two adjacent partition walls among the partitions walls are arranged almost symmetrically around a plane which passes through the center of the merging portion and is parallel to a direction in which the largest force is generated by thermal expansions of the exhaust ports.

Abstract: In a honeycomb catalytic converter having a metal case, a honeycomb catalyst mounted in the metal case, and a securing member used for mounting the honeycomb catalyst in the metal case and arranged between an outer surface of the honeycomb catalyst and an inner surface of the metal case, at lest one of an inlet portion and outlet portion of the honeycomb catalyst has a double cone structure in which an inner cylindrical member is arranged in the metal case. The honeycomb catalytic converter mentioned above can mount the honeycomb catalyst stably in the metal case for a long period of time even when exposed to high temperatures.

Abstract: At the time of engine low load operation, the air-fuel mixture is stratified in the state where the average air-fuel ratio in the combustion chamber (5) is lean. The NO.sub.x generated at this time is absorbed by the NO.sub.x absorbent (26) provided in the exhaust passage. When making the average air-fuel ratio in the combustion chamber (5) rich so as to cause the releasing of the NO.sub.x from the NO.sub.x absorbent (26), the air-fuel ratio of the air-fuel mixture around the spark plug (10) is kept from changing and the average air-fuel ratio in the combustion chamber (5) is changed from lean to rich.

Abstract: A thermal reactor for reducing exhaust emissions generated by an engine. The thermal reactor preferably includes an outer housing and an inner core mounted within the outer housing. The inner core defines an expansion chamber which receives exhaust gas from the engine. When the exhaust gas enters the expansion chamber, it expands and becomes thoroughly mixed. While in the expansion chamber, at least some of the exhaust gas is oxidized. A single-layered recirculation chamber is located between the outer housing and the inner core. The recirculation chamber receives the exhaust gas from the expansion chamber and recirculates the exhaust gas around the outer surface of the inner core such that the inner core is insulated. By insulating the inner core with heated exhaust gas from the expansion chamber, the expansion chamber maintains a high temperature which facilitates oxidation of the exhaust gases.

Abstract: Flow diverter methods and apparatus useful, for example, in adsorber systems capable of meeting the California ultra-low emission vehicle (ULEV) standard, are described, the adsorber systems incorporating a combination of a burn-off catalyst and a modified adsorber constructed with an open flow region of substantially unobstructed flow having a hole or a region of larger cell openings, the flow diverter acting to control exhaust flow through the adsorber to both increase adsorption and reduce the light-off time of the burn-off catalyst.

Abstract: Two catalytic converters are disposed in series midway in an engine exhaust passage, and a by-pass valve selectively introduces exhaust into the upstream converter and a by-pass passage which by-passes the converter. When the catalyst temperature of the upstream catalytic converter exceeds a threshold value A, exhaust is routed to the by-pass passage. The catalyst temperature in the state when exhaust is routed to the upstream catalytic converter under steady state engine running conditions is stored as a convergence temperature depending on the engine running conditions.When exhaust is routed to the by-pass passage, exhaust is re-introduced into the upstream converter only when both the catalyst temperature and the convergence temperature corresponding to the running conditions at that time are less than a threshold value B which is less than the threshold value A.In this way, hunting of the by-pass valve operation is prevented.

Abstract: An improved auxiliary heat source for use in an engine cold start emission reduction system includes a flame containment chamber having at least one wall formed of a porous foam material that confines the flame within a predetermined chamber while permitting heat therefrom to emerge and flow to an exhaust system catalyst or, in the case of diesel engines, a particulate trap.

Abstract: A device for catalytically converting exhaust gases in an exhaust system, especially an exhaust system of an internal combustion engine, preferably for Otto engines, includes at least two honeycomb bodies which are disposed in an outer jacket tube and through which an exhaust gas can flow in succession. The adjacent honeycomb bodies are joined to one another through the use of support elements protruding into the honeycomb bodies. The first honeycomb body is spaced apart relative to the outer jacket tube and has at least two shells joined to a jacket surface of the first honeycomb body, which are each connected to an electrical power lead. Electrically insulating joining elements each have one end joined to a shell and another end joined to the adjacent second honeycomb body. The outer jacket tube has at least one encompassing bead, which rests on a jacket tube of the second adjacent honeycomb body.

Abstract: An exhaust header system for an internal combustion engine having improved exhaust gas flow characteristics. Primary pipes extend from openings in a flange bolted to the engines exhaust ports. The primary pipes come together at a collector pipe into which the primary pipes extend slightly. The ends of the primary pipes are substantially parallel, uniformly spaced around the collector pipe axis and have end surfaces lying substantially in a single plane. A generally pyramidal transition piece has a base corresponding to, and secured to, the primary pile end surfaces so as to cover the area between the pipe ends. The pyramid apex extends along the collector pipe centerline toward the exit end. The length and cross section of the transition piece is selected to provide a smooth transition from the greater combined internal cross section of the primary pipe ends to the lesser cross section of the collector pipe exit end.

Abstract: An exhaust gas purifying apparatus with a failure diagnosis function is provided. A failure diagnosis device determines that the apparats is failed when the temperature rising speed of an adsorbing device is equal to a set value or less during a gas adsorption process and if the temperature rising speed is equal to an upper limit or more or to a lower limit or less during a gas desorption process. Further, a failure diagnosis device similarly monitors the flow passing through the adsorbing device. A failure diagnosis device determines that the apparatus is failed if the concentration of discharge gas is equal to a set value or more in a discharge passage. And further, a failure diagnosis device measures the concentration of discharge gas flowing through a return passage to accumulate the amount of discharge gas in order to determine that the apparatus is failed if the accumulated value is equal to a set value or less.

Abstract: A lean burn engine adapted to establish a specified air-fuel ratio leaner by predetermined rate than a stoichiometric air-fuel ratio in a range of low engine speeds and low engine loads is provided with an air intake system of a low speed type which provides a high charging efficiency in a range of low engine speeds and an exhaust system capable of eliminating a nitrogen oxide emission in the exhaust even during lean burning.

Abstract: An internal combustion engine has a cylinder assembly including a cylinder block and a cylinder head mounted thereon, the cylinder assembly having an exhaust passage defined in the cylinder block and a water jacket defined therein around the exhaust passage. A water jacket cover is mounted on an outer surface of the cylinder block in covering relation to the water jacket, and has an opening defined therein. The cylinder block has an air inlet passage defined therein across the water jacket and communicating with the opening and the exhaust passage. A valve cover is mounted on an outer surface of the water jacket cover. The water jacket cover and the valve cover jointly define a valve chamber therebetween. A valve is disposed in the valve chamber for selectively introducing air from the valve chamber through the opening and the air inlet passage into the exhaust passage to assist in burning harmful unburned components contained in an exhaust gas flowing through the exhaust passage.

Abstract: An exhaust manifold has a plurality of double pipes, each of which includes an inner pipe and an outer pipe, and a collecting pipe to which each of the double pipes is connected. The outer peripheral portion of the outer pipe is secured to the collecting pipe, and a thermal insulating layer of air, which is formed as a closed space so that substantially no exhaust gas will penetrate it, is disposed on an inner peripheral side of the portion at which the outer periphery of the outer pipe is secured to the collecting pipe. Owing to the presence of the thermal insulating layer, heat is not transmitted to the welded joint directly via the inner and outer pipes.

Abstract: A change-over valve unit has a change-over valve for switching a bypass passage and an exhausting passage disposed in parallel therewith. An adsorbent is disposed in the bypass passage to adsorb exhaust components. An actuator of the change-over valve is isolated from an adsorption cylinder by a pedestal. Furthermore, rotary shafts of the control mechanism of the change-over valve are positioned within the bypass passage of the adsorber when the change-over valve is positioned to open the main exhaust passage. Thus, the heat of the exhaust gas flowing through the main exhaust passage is not transmitted to the rotary shafts.

Abstract: A catalytic device is disclosed, in which a catalytic layer is electrically heated and activated. In one form, the quantity of the catalytic layer is greater near a gas outlet than near a gas inlet of the device. In another form, the catalytic layer is disposed only near the gas outlet. The catalytic layer can be quickly activated so as to promote purification of exhaust emissions immediately following the ignition.