Abstract: A vacuum cut-off valve for cutting off vacuum communication between an inlet port and an outlet port when the inlet vacuum increases above a predetermined vacuum level so that the outlet vacuum is maintained at a constant predetermined vacuum level. When the valve cutting operation between the inlet port and the outlet port is insufficient and vacuum leakage results, atmospheric pressure is admitted to the outlet port to thereby maintain the outlet vacuum at the constant predetermined level.

Abstract: Disclosed is a secondary air feeding device for feeding secondary air into the exhaust passage located upstream of the catalytic converter. A diaphragm type secondary air control valve is provided for usually controlling an amount of secondary air fed into the exhaust passage. Said secondary air control valve stops the feeding operation of secondary air at the time of idling.

Abstract: An air control valve for a vehicle emissions control system has an inlet connected to the output of the vehicle air pump, a first outlet connected to exhaust injection passages in cylinder head, and a second outlet connected downstream into the exhaust manifold. A vacuum actuated valve element is responsive to engine manifold vacuum to divert the output of the air pump from the downstream injection point to the upstream injection point during cold engine operation. However, the air supply from the air pump is diverted from the upstream injection point to the downsteam injection point for a few seconds when a sudden increase in manifold vacuum occurs, such as during engine deceleration when the engine is cold. After the engine warms up, the air supply from the air pump is continuously communicated to the downstream injection point.

Abstract: Disclosed is an exhaust gas cleaning apparatus of an internal combustion engine, provided with a three-way catalytic converter, an air-fuel ratio sensor and a secondary air injection system. The secondary air injection system has a diaphragm-operated flow control valve for increasing or decreasing the amount of secondary air introduced into the exhaust manifold of the engine in accordance with electrical signals transmitted from the air-fuel ratio sensor. Means are provided for rapidly increasing or decreasing the air-fuel ratio to a stoichiometric value at the moment when the amount of secondary air passed through the flow control valve is increased or decreased. Therefore, the air-fuel ratio is maintained quite near the stoichiometric value at which the three-way catalytic converter can effectively operate to clean the three major toxic components in the exhaust gas.

Abstract: Disclosed is an apparatus for purifying exhaust gas discharged from an internal combustion engine having four cylinders. The apparatus comprises: an exhaust pipe provided with two entrance pipes, each of which is communicated with two engine cylinders, respectively, and a joint joining the entrance pipes together; a three way catalyzer for converting the exhaust gas disposed at a position downstream of the joint; a secondary air device for supplying secondary air into the exhaust pipe device, the secondary air device being communicated with the first entrance pipe; an air switching device, the entrance of which is communicated with the secondary air device and the exit of which is communicated with the second entrance pipe, for switching secondary air, and; a device for detecting the operating characteristics of the engine and for actuating the air switching device.

Abstract: Disclosed is a secondary air control device disposed in a system for supplying secondary air into an exhaust system of an internal combustion engine for purifying exhaust gas emitted from the engine. The secondary air control device comprises a first valve device actuated by an ON-OFF vacuum signal for stepwisely controlling the flow of secondary air in response to the ON-OFF vacuum signal, and; a second valve device, which is a delay system with a predetermined delay time, actuated by the ON-OFF vacuum signal for controlling the flow of secondary air. Accordingly, the secondary air control device can control the flow of secondary air, which comprises a step flow generated by the first valve device, and a delayed flow generated by the second valve device, in accordance with the ON-OFF vacuum signal.

Abstract: An electromagnetic type vacuum switching valve adapted for connecting a vacuum actuator of an exhaust gas cleaning apparatus to a vacuum signal port in an intake manifold of an internal combustion engine or to the atmosphere. The valve is provided therein with an orifice means for controlling the rate of introducing the vacuum signal or the rate of introducing the atmospheric air pressure signal, and with a filter means for preventing dust in the atmosphere from entering into the engine.

Abstract: Disclosed is an apparatus for controlling secondary air for purifying exhaust gas discharged from an internal combustion engine. The apparatus comprises a pair of catalytic converters disposed in series within an exhaust system, a secondary air switching device communicated with two positions each of which is located respectively upstream of each of the catalytic converters, an actuating device for selectively communicating the secondary air switching device with each of the above-mentioned two positions, and a detecting device for detecting the temperature of the first catalytic converter located upstream of the second converter.If the detecting device detects a condition wherein the temperature of the first catalytic converter is lower than a predetermined level, secondary air is supplied to the position upstream of the first catalytic converter.

Abstract: Disclosed is a secondary air feed control device comprising a movable valve and a movable valve seat having a first and a second valve port. The first valve port is connected to the secondary air inlet disposed in the exhaust pipe, while the second valve port is connected to the atmosphere. The movable valve is arranged between the first and second valve ports so as to co-operate with the first and second valve ports. An oxygen concentration detector, providing a detecting signal indicating that the total air-fuel ratio is smaller than the stoichiometric air-fuel ratio, is disposed in the exhaust pipe. The opening area of the first valve port is controlled so as to be increased in accordance with an increase in the level of the load of the engine and in response to the detecting signal when the total air-fuel ratio becomes smaller than the stoichiometric air-fuel ratio.

Abstract: Disclosed is an exhaust gas cleaning apparatus of an internal combustion engine, provided with a three-way catalytic converter and a vacuum-operated flow control valve having a diaphragm for controlling the amount of secondary air directed into an exhaust manifold of the engine for an effective operation of the three-way catalytic converter. The diaphragm operates to increase or decrease the amount of secondary air in accordance with the change of vacuum force on the diaphragm, which force is generated by a vacuum signal transmitted into the valve from an intake manifold of the engine. Means are provided for compensating the difference in the vacuum levels between a high-load condition and a low-load condition so that the rate of increase in the vacuum force of the diaphragm is substantially kept near a constant value for every kind of engine condition. Thus, an ideal operation of the three-way catalytic converter can be obtained.

Abstract: A secondary air control system for an internal combustion engine having an exhaust system provided with exhaust gas treating means adapted for secondary air injection and including a relief valve includes a mechanism which keeps the relief valve open after the valve is opened by a predetermined pump discharge pressure, until a predetermined lower pressure is reached.

Abstract: A composite valve made of a first dish-like member having an open face and concaved portions defining diaphragm chambers, a second dish-like member having an open face and concaved portions defining complex passages, an intermediate member having opposite open faces opposing the open faces of the first and second dish-like members and complex partitions defining bearing portions and complex passages, a diaphragm element interposed between the first dish-like member and the intermediate member, valve elements slidably mounted in the bearing portion and connected to the diaphragm element, and valve seat elements interposed between the second dish-like element and the intermediate member and providing valve seats.

Abstract: Secondary air fed to the exhaust system of an engine is controlled by controllably venting the secondary air passing through a secondary air supply conduit leading to the exhaust system using a diaphragm unit operated valve. Vacuum applied to the diaphragm unit is controlled by cooperation of the venturi vacuum and the pressure differential between two interior portions of the secondary air supply conduit to supply the exhaust system with an appropriate amount of secondary air to the exhaust gas amount.

Abstract: Disclosed is an exhaust gas cleaning apparatus of an internal combustion engine, provided with a three-way catalytic converter and a vacuum-operated flow control valve. The flow control valve has a diaphragm for controlling the amount of secondary air directed into an exhaust manifold of the engine for the effective operation of the three-way catalytic converter. In order to move the diaphragm to increase or decrease the amount of secondary air, a vacuum chamber is formed on one side of the diaphragm. This vacuum chamber is opened to a vacuum port formed in the intake system of the engine for transmitting the vacuum signal from the port to the vacuum chamber. Further, in order to maintain a constant rate of movement of the diaphragm irrespective of the vacuum level at the port, means are provided for transmitting a vacuum signal from the port to another vacuum chamber formed on the other side of the diaphragm.

Abstract: The air-fuel ratio of the mixture supplied into the combustion chambers of the engine is controlled to a required value suitable for attaining a stable and smooth running of the engine and the oxygen-combustibles ratio of the exhaust gases introduced into the exhaust gas purifying device is controlled to a required value suitable for causing the purifying device to effectively function, utilizing feedback techniques performed in response to the composition of the exhaust gases passing upstream of the purifying device.

Abstract: Disclosed is an automotive multi-cylinder internal combustion engine in which exhaust gases from one or more of the exhaust ports of the engine cylinders are partially recirculated into the mixture induction system of the engine and secondary air is injected into exhaust gases from the remaining exhaust ports under normal operating conditions of the engine. The recirculation of the exhaust gases is interrupted and furthermore secondary air is injected into the exhaust gases from all the engine cylinders under predetermined non-normal operating conditions such as idling and decelerating conditions of the engine.

Abstract: An exhaust gas purifying system for automobile engines or like engines of the type injecting a secondary air for burning the unburned part of the exhaust gases produced in an engine and more particularly an improved purifying system of the type whereby the injection is automatically cut off especially when the engine speed is rapidly decelerated, accelerated, or the engine runs under high loads, in which an air injection conduit is closed by the action of a valve which is actuated by detecting a drop or decrease in a suction vacuum in the engine as the engine is increasing its speed or is running under high loads, and is closed by the action of the aforementioned valve which is actuated under the action of a valve which is operable in response to rapid increases the suction vacuum suffers as the engine speed is rapidly diminishing.

Abstract: A relief pressure control valve for controlling the pressure in a secondary air supply line has first and second pressure chambers divided by a diaphragm, a spring for biasing the diaphragm towards the second pressure chamber, a relief port connected to the secondary air supply line, a valve head connected to the diaphragm and being biased to close the relief port.The air pumped out from an air pump is supplied to the first pressure chamber and the first pressure chamber is communicated with the second pressure chamber through an orifice. Accordingly, during stable running operations of the engine, the pressures in the first and second pressure chambers are made equal by means of the orifice, while during the accelerations pressure difference is produced between the chambers for a certain time period.

Abstract: A secondary air supply control system including: an air cleaner; an air pump connected to the air cleaner; a valve having a first chamber and a second chamber, which are separated by a diaphragm and communicated with each other through a first orifice, and controlling the supply of secondary air from the air pump to an exhaust manifold, in response to deflection of the diaphragm; and a passage connecting the second chamber to an intake manifold in a position downstream of a throttle valve in a carburetor and having a second orifice. In addition, a check valve which allows the flow of the secondary air only in the direction towards the exhaust manifold is provided in a passage interconnecting the valve and the exhaust manifold. In this system, an open cross-sectional area of the first orifice is smaller than that of the second orifice provided in the aforesaid passage.

Abstract: A device for supplying secondary air in proportion to the volume of intake air into the exhaust manifold of an internal combustion engine without any adverse effects on an exhaust gas recirculation system, the device comprising a secondary air supply pipe communicated with the exhaust manifold, means for supplying secondary air through the secondary air supply pipe into the exhaust manifold, secondary air control valve means disposed in the secondary air supply pipe for controlling the flow rate of secondary air flowing therethrough, means for detecting the volume of intake air to said engine, means for detecting the volume of the secondary air flowing through the secondary air supply pipe, and means responsive to both the signal representative of the detected volume of intake air and the signal representative of the detected volume of the secondary air supply for controlling the secondary air control valve means in such a way that the secondary air supply may be in proportion to the volume of intake air.

Abstract: An engine exhaust gas purification system having an exhaust gas reactor mounted on the engine exhaust pipe, a secondary air supply system having a secondary air supply passage connected to the exhaust pipe upstream of the reactor, and an exhaust gas air-fuel ratio detector mounted on the exhaust pipe to detect air-fuel ratio of exhaust gases in the exhaust pipe. A secondary air supply control valve is provided in the secondary air supply passage and controlled by a valve actuator having a diaphragm to which positive pressure of the secondary air and the engine intake vacuum pressure can be applied. The application of the positive and vacuum pressures to the diaphragm is controlled by solenoid valves which are controlled in accordance with the air-fuel detector output voltage which represents the detected exhaust gas air-fuel ratio, whereby the secondary air supply control valve is controlled such that the secondary air is supplied to the engine exhaust gases at a continuously controlled, variable rate.

Abstract: Disclosed is an exhaust gas cleaning apparatus of an internal combustion engine, provided with a three-way catalytic converter, an air-fuel ratio sensor in the form of an oxygen concentration-cell which detects an air-fuel ratio higher than a stoichiometric air-fuel ratio at which the converter effectively operates, and a secondary air injection system adapted for increasing or decreasing the amount of secondary air introduced into the exhaust pipe of the engine in accordance with electrical signals transmitted from the air-fuel ratio sensor. Means are provided for controlling the speed of introduction of secondary air so that the speed of decreasing the amount of secondary air is higher than the speed of increasing the amount of secondary air. Therefore, the air-fuel ratio of the exhaust gas is effectively controlled by signals transmitted from the sensor to approximate the stoichiometric ratio.

Abstract: Disclosed is a secondary air control valve device for feeding secondary air controlled in correspondence with the engine load into an exhaust system having a catalytic converter for reducing hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO.sub.x) contained in exhaust gas emitted from an internal combustion engine. The device is simple in construction and can vary the predetermined amount of secondary air in correspondence with the changes of the characteristic of the catalyzer which may vary as the catalyzer is activated, so that the amount of the secondary air is controlled for maintaining the highest converting efficiency for a long duration of use of the vehicle which has this device mounted thereon.

Abstract: An engine having an even number of cylinders is caused to produce two differently composed exhaust gases, one rich in air and the other in unburned fuel and CO, from the two groups of cylinders each consisting of half the number of cylinders being fired in succession, which exhaust gases are fed separately to a thermal reactor and allowed to gradually mix with each other for mild and slow reaction therein.

Abstract: A device is disclosed which is intended to regulate the rate of flow of air injected into an exhaust-gas stream of an internal combustion engine exhaust system in order to complete post-combustion of the exhaust gas and reduce air pollution, said device being a variable-section valve which is actuated by an active member responsive to the negative pressure existing in the air-induction duct of the engine. An alternative embodiment is also disclosed in which means are provided to make the adjustment finer. Excessive cooling of the exhaust gas stream is avoided and the efficiency of the exhaust system in general is improved, including the case in which catalytic mufflers are adopted.

Abstract: An apparatus is provided for introducing secondary air for into an internal combustion engine. The apparatus has an air pump coupled to an air injection pipe system, the latter having an end terminating upstream of the catalytic converter, for introducing an amount of secondary air into the exhaust system of the engine. The apparatus further includes a valve device for maintaining the secondary air directed to the exhaust system from the air pump at determined constant pressure; thus, the amount of secondary air introduced into the exhaust system is effectively decreased during high rotational speed engine operation in order to prevent the catalytic converter from being overheated.

Abstract: In a system comprising a diaphragm type control valve with a diaphragm and a pair of chambers divided by the diaphragm, a plurality of orifices connecting the chambers and a thermo sensitive valve, the valve opening or closing period of the diaphragm type control valve is changed longer or shorter by opening and closing a bypass passage around one of the orifices by the thermo sensitive valve in response to temperature relative to the engine operating condition, whereby exhaust gas purification is attained with complete prevention of afterburn.

Abstract: A system for supplying secondary air into an exhaust system of an internal combustion engine in a manner such that the amount of secondary air is proportional to the engine intake air. The supply of the secondary air is controlled by a valve member which is biased in response to a balance between a venturi vacuum and the exhaust gas pressure until a predetermined ratio of the venturi vacuum to the exhaust gas is obtained.

Abstract: An exhaust pressure responsive flow control valve is disposed in a secondary air supply passageway leading from the atmosphere to engine exhaust system. The valve has a valve member of a material which is movable by influence of magnetic fields and an electromagnet means for urging the valve member toward a valve closed position upon passing of electric current therethrough. First circuit means is provided which permits a relatively large current through the electromagnet when the exhaust gas temperatures are so high as to overheat the exhaust reactor or converter closing the valve to block secondary air supply through the passageway. Second circuit means is provided which permits a relatively small current through the electromagnet at normal stable operating conditions of the engine to restrict secondary air supply. At acceleration when a relatively large amount of secondary air is required no current is permitted through the electromagnet to open the valve.

Abstract: Disclosed is an apparatus for introducing secondary air into an exhaust system of an internal combustion engine, provided with a three-way catalytic converter in the exhaust system. The apparatus includes a flow control valve adapted for controlling the amount of air introduced into the exhaust system in accordance with the atmosphere of the exhaust gas so as to cause it to be kept near a stoichiometric atmosphere, and a pressure control valve adapted for keeping a predetermined constant pressure difference of the secondary air between a position upstream from the flow control valve and a position downstream from the flow control valve. The atmosphere control operation by the flow control valve is effectively promoted by the pressure control valve, so that atmosphere of the exhaust gas can be strictly and precisely controlled to said stoichiometric atmosphere for proper operation of the three-way catalytic converter.

Abstract: A control system for adjusting the amount of a secondary air to be fed into the exhaust system, comprising a secondary air control valve (ACV) for controlling the amount of the secondary air from an air pump, vacuum switching valves (VSV) alternately effecting an operative vacuum on the ACV, and a vacuum control valve (VCV) which is connected to the VSV via a first vacuum reservoir tank and to the intake vacuum area via a second vacuum reservoir tank.

Abstract: In a process for the afterburning of the combustible pollutants from an internal combustion engine, in order to automatically reduce the secondary induction rate when power increases without using a controlling valve actuated by the carburettor venturi depression, there is provided a volumetric efficiency of the secondary air pump linked to and activated by the engine and a volumetric efficiency which decreases when the ratio between its back pressure and suction pressure increases, this reduction being achieved through the proper selection of the pump volumetric comression ratio r: between 0.6 c and 1.3 c when a steeply decreasing trend is required, and above 1.3 c if a slower and slower decreasing trend is required. To perform this process an afterburner apparatus has a nitrogen oxide reducing catalyst placed inside the afterburner reactor on the gas stream immediately at the outlet of a torus, in which the gases are homogenized and their reaction with preinjection air is terminated.

Abstract: Disclosed is an internal combustion engine comprising a carburetor and a secondary air feed control valve for feeding secondary air into the exhaust system of the engine from the air pump driven by the engines. The engine further comprises a temperature detector for indicating whether the warm-up of the engine is completed, and a gear position detector for indicating whether the shift gear of the transmission of the engine is in the top gear position. A relatively lean air-fuel mixture is fed into the cylinder of the engine and a relatively small amount of secondary air is fed into the exhaust system when the shift gear of the transmission is in the top gear position after completion of the warm-up of the engine.

Abstract: In an engine having a pump for delivering air to the exhaust system to support oxidation of exhaust gases, a valve opens when air delivered by the pump exceeds a selected temperature to bleed air from the pump into the vacuum chamber of a diaphragm operated valve. In one embodiment the valve diverts air from the exhaust system to relieve the backpressure on the pump, while in another embodiment the valve closes an exhaust gas recirculation passage to improve efficiency of operation.

Abstract: A system for introducing secondary air into gas exhausted from an internal combustion engine of the carburetor type, provided with a three-way catalytic converter in the exhaust system of the engine. The system includes a flow control valve having a diaphragm operated valve member for controlling the amount of secondary air in accordance with electric signals from a .lambda.-sensor arranged in an exhaust system of the engine so that excess air ratio .lambda. of the exhaust gas, which is introduced into the three-way catalytic converter, is controlled near 1.0. Therefore, effective cleaning operation of the three-way catalytic converter is expected.

Abstract: An internal combustion engine provided with an EFI (electronic fuel injection) system, in which the ratio of the amount of air introduced into the engine intake system to the amount of fuel supplied to the combustion chamber is controlled to a predetermined constant ratio irrespective of engine operating conditions, is disclosed. A part of the introduced air is diverted from the intake pipe in accordance with the engine operating condition, and is introduced into the exhaust system or re-introduced into the intake system of the engine when the engine is operating under particular conditions. Thus, a rich air-fuel mixture, which is, for example, suitable for a particular engine operating condition, can be supplied to the engine combustion chamber.

Abstract: A valve regulates the pressure of secondary air discharged from a pump to a constant value. A second valve then meters the flow in accordance with the amount of air taken into the engine.

Abstract: Secondary air is fed into the engine exhaust gas passageway at a position upstream of an oxygen sensor to cause the electric air-fuel ratio control device and the air-fuel mixture generator to provide an air-fuel mixture having an air-fuel ratio lower than a set desired air-fuel ratio during idle and slow speed running of the engine.

Abstract: In a system for delivering secondary air from an air pump to either the exhaust manifold, preferably, closely adjacent to the exhaust ports, or to a converter in the exhaust system of an internal combustion engine, an integral air switching diverter valve assembly having an inlet connected to the air pump, a primary discharge outlet for delivery of air to the exhaust manifold and a secondary discharge outlet for delivery of air to the converter, a valve being mounted in the assembly for movement between a first or converter mode position at which it is normally positioned to allow secondary air flow to the converter while blocking secondary air flow to the exhaust manifold and a second or port mode position to allow secondary air flow to the exhaust manifold while blocking air flow to the converter, the assembly including a differential pressure operated switching diaphragm assembly used to effect movement of the valve between the port and converter modes, a divert timing assembly operative during deceleratio

Abstract: An apparatus cleans the exhaust gases of a motorcycle by feeding secondary air to the exhaust path of the engine. The amount of secondary air fed is controlled in proportion to the speed of the motorcycle. The apparatus includes a control valve which is operated to be opened and closed in response to the opening and closing of the throttle valve of a carburetor of the engine.

Abstract: An exhaust gas purifying device for an internal combustion engine, comprising a catalytic converter containing a three way catalyzer therein, a first oxygen sensor disposed in the exhaust passage, and an air-fuel ratio regulating means for regulating an air-fuel ratio of the mixture fed into the cylinder of the engine so as to conform it to the stoichiometric air-fuel ratio in response to an output signal of said first oxygen sensor over a larger range of running conditions of a vehicle.

Abstract: A non-return air flow system for supplying secondary air into the exhaust system of internal combustion engines by utilizing pulsating flow of exhaust gases in the exhaust system, wherein the critical valve opening pressure for a check valve incorporated in the non-return system is varied in accordance with intake air flow rate of the engine so that supply of secondary air is effected in proportion to air intake of the engine.

Abstract: An air switching diverter valve assembly for use with an internal combustion engine to control the flow of secondary air from an air pump, the air switching diverter valve assembly including a housing having a valve chamber therein with an inlet from the air pump to the valve chamber, a first outlet to supply air to the engine exhaust manifold, a second outlet to supply air either to the converter or to the atmosphere, depending on the intended use of the valve in an engine system, and a pressure valve controlled third outlet, a valve movably positioned in the valve chamber for control of flow out through either the first outlet or the second outlet, a switching diaphragm assembly being operatively connected to the valve for actuation thereof and positioned in the housing to form therewith first and second chambers on opposite sides of the switching diaphragm, the second chamber being connected to receive an engine manifold vacuum signal and, a divert timing assembly positioned in the second chamber and attac

Abstract: An anti-afterburn system for an engine having an air pump, comprising a pressure differential responsive member defining two chambers, a control valve connected to said member, and at least one orifice provided in one of conduits connecting the chambers with an intake manifold of the engine to operate the control valve upon abrupt pressure variation in the intake manifold thereby preventing afterburn. The system further comprises a thermo valve means which is responsive to overheating of the engine or an exhaust system thereof and adapted to supply a pressure to one of the chambers to operate the control valve, thereby interrupting supply of the secondary air from the pump to prevent damages of a thermal reactor and generation of fire.

Abstract: A control unit creates a control pressure signal which causes a pressure responsive valve assembly to interrupt the flow of secondary air to the exhaust system of an internal combustion engine during prolonged heavy load operation.

Abstract: A diaphragm actuated valve having inlet, outlet and bypass ports is provided with two independently operating valves on a diaphragm rod stem of a diaphragm assembly. One of the valves operates as a main air valve and the other valve provides positive relief of air pressure when that pressure reaches a predetermined value. The preferred embodiment of the valve structure is a sheet metal construction including a cap closing and delimiting a diaphragm chamber. The cap structure has a diaphragm stop means integrally formed with it which limits diaphragm movement during valve operation.

Abstract: An arrangement for deriving intake negative pressure from an internal-combustion engine, comprising a carburetor in the latter, with an intake for an air -- fuel mixture, a throttle valve therein for regulating the mixture, and at least one longitudinal passage therein for guiding the mixture toward the engine; an intake passage leading from the carburetor to the engine; which latter also has an exhaust passage leading therefrom; wherein the throttle valve has a shaft substantially transversally disposed in one of the passages of the carburetor, the latter being fitted with a discharge opening in a side wall of the intake passage to derive negative passage from the carburetor for regulating and controlling the engine operation; the discharge opening being provided in the flow of the mixture, in an area that is directed downstream from the throttle-valve shaft; whereby to avoid accumulation and discharge of condensed fuel from the carburetor to the discharge opening.

Abstract: In an automobile engine exhaust gas cleaning system including an exhaust gas reactor which is supplied with auxiliary air for effecting combustion of unburnt constituents such as CO and HC in the exhaust gas, an air flow control device is provided for controlling the supply of the auxiliary air. The control device includes a first control valve disposed in the auxiliary air supply passage and controlled in response to the engine intake pressure so that it is opened when the engine intake vacuum is above the wide-open throttle vacuum, and a second control valve for controlling the supply of the engine intake vacuum to the first control valve in such a manner that it allows the engine intake vacuum to pass into the first control valve when the vacuum is lower than the value that is produced during deceleration and that it introduces atmospheric pressure to the first control valve when the vacuum increases to the value that is produced during deceleration.

Abstract: A spark-ignition multiple cylinder internal combustion engine for an automotive vehicle, comprising a first set of cylinders operative on a relatively rich air-fuel mixture and a second set of cylinders operative on a relatively lean air-fuel mixture and having a thermal reactor incorporated into the exhaust system, the internal combustion engine being characterized by a comprehensive emission control system uniting various subsystems of the engine such as the air-intake, mixture induction, exhaust and ignition systems which are provided with means for cooling the thermal reactor by forced air in response to an unusual rise of the temperature of the thermal reactor, means for warming up air in the air-intake system at a rate related to engine load and the temperature of air in the intake system, means for supplying secondary air in accordance with the varying operating conditions of the engine, and means for retarding ignition timing during driving a cold engine.

Abstract: An air-pollution preventive arrangement for use with an internal combustion engine for motor vehicles, adapted to reduce the concentrations of noxious compounds such as unburned hydrocarbons and carbonmonoxides contained in the engine exhaust gases. The arrangement comprises a thermal reactor for primarily re-combusting the exhaust gases and a catalytic converter for secondarily recombusting the exhaust gases passed from the thermal reactor so as to oxidize the residual unburned compounds. An air injection unit supplies additional air which is admixed, in a limited proportion, to the exhaust gases entering the thermal reactor to aid in the primary re-combustion of the exhaust gases therein. The noxious unconsumed hydrocarbons and carbon-monoxides are thus converted into innocuous compounds at efficiencies which are far higher than those attained where the thermal reactor or the catalytic converter is employed independently.