Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Mitsubishi Fuso Truck & Bus Corporation

Keiki Tanabe

Susumu Kohketsu

Shinji Nakayama

Susumu Kouketsu

Seijiro Kotooka

Daisuke Sunohara

Hitoshi Yokomura

There is provided an apparatus that estimates the NOx adsorption amount, comprising a NOx trap catalyst that is disposed in an exhaust passage of an engine, for adsorbing NOx in exhaust gases during lean operation and releasing and reducing the adsorbed NOx during rich operation, an operation unit that computes an amount of emission from the catalyst during rich operation by using a map or a polynomial equation that reflects emissions from the catalyst based on the exhaust gas temperature and the exhaust gas flow rate of the exhaust passage and the excess-air factor upstream of the catalyst, and an estimating unit that estimates an amount of adsorption in the NOx trap catalyst from the computed emission amount.

Apparatus and method for estimating NOx trap catalyst adsorption amount

Immediately before fuel pressure is increased by a pressure-increase mechanism, a pressure-increase control valve of each cylinder is opened in timing that does not overlap the timing of opening of an injection control valve, and the period of time for which the pressure-increase control valves is opened is gradually increased. As a result, it is possible to prevent the quantity of fuel consumed by the pressure-increase mechanism from rapidly increasing when the increase of fuel pressure is started.

Common rail fuel injection system

A booster unit is provided in an injector of a fuel injection system. The booster unit comprises a booster piston accommodated in a pressure chamber, and a discharge valve capable of discharging fuel in a backpressure chamber. A controller has an indication-value setting step of setting an indication value of a target pressure in a common rail in correspondence to an engine operation state, a determination step of determining whether or not the indication value of the pressure in the common rail is in a direction of reduction to be lower in comparison to a previously set indication value, and a step of prolonging an open time of a discharge valve of the booster unit when the determination step has determined that the indication value is in the direction of reduction.

Fuel injection system

A booster unit is provided in an injector of a fuel injection system. The booster unit includes a booster piston accommodated in a pressure chamber, and a discharge valve capable of discharging fuel in a backpressure chamber. A needle valve drive unit includes a pressure-receiving piston and an open/close valve. A return passage is connected to a discharge side of the open/close valve. A fuel discharge passage in communication with the discharge valve is combined with the return passage in a confluence portion. A check valve is provided between the confluence portion and the open/close valve. A check valve permits the fuel discharged to the return passage from a pressurization chamber to be directed to the confluence portion, and prevents the fuel discharged to the fuel discharge passage from the backpressure chamber from being directed the open/close valve.

A booster unit is provided in an injector of a fuel injection system. The booster unit includes a booster piston accommodated in a pressure chamber, and a discharge valve capable of discharging fuel in a backpressure chamber. A controller includes an indication-value setting step which sets an indication value of a target pressure in a common rail in correspondence to an engine operation state, a determination step which determines whether or not the indication value of the pressure in the common rail is in a direction of reduction to be lower in comparison to a previously set indication value, and a booster piston pseudo-operation step which opens the discharge valve at timing other than injection operation of the injector when the determination step has determined that the indication value is in the direction of reduction.

A pressure-elevating type fuel injecting system selectively injects via injectors fuel stored in a common rail or fuel whose pressure is elevated by a pressure elevating mechanism into a combustion chamber, and comprises a crank angle sensor producing crank pulse signals in accordance with operating states of an engine, a pulse interval calculating unit calculating pulse intervals between respective crank pulse signals, and a determination unit determining the malfunction of the pressure elevating mechanism when a variation of the pulse interval is above a determination threshold.

Pressure-elevating type fuel injecting system

An accumulator type fuel injection system adapted to prevent engine trouble by making a judgement that fuel injection rate switching change-over valves provided correspondingly to fuel injection nozzles in cylinders, a valve for controlling the pressure in a low-pressure accumulator or means for detecting fuel pressures in accumulators gets out of order, and carrying out when any of these parts break down a control operation of a limp-home mode in which a region of an operation of an engine is limited. To provide such an accumulator type fuel injection system, a control means is formed so that, when a judgement that first control valves , a second control valve or pressure sensors for detecting the fuel pressures in the respective accumulators get out of order is given, the control means sets a discharge pressure of a fuel pump not higher than a permissible pressure in a second accumulator , and injects a fuel from fuel injection nozzles

Accumulator type fuel injection system

A pressure-elevating type fuel injecting system pressurizes high pressure fuel from a pressure accumulating chamber using a pressure-elevating mechanism and injects the pressure-elevated fuel into combustion chambers by injectors. The pressure-elevating type fuel injecting system comprises a target fuel injection quantity setting unit which sets a target fuel injection quantity, a time difference setting unit which sets a time difference between a timing for opening an injector electromagnetic valve and a timing for operating an pressure-elevating mechanism electromagnetic valve, an initial fuel injection quantity calculating unit calculating an initial fuel injection quantity on the basis of a time-dependent variation of fuel pressure and the time difference, and a final injection period setting unit which calculates an operation period of the injector electromagnetic valve, on the basis of a final fuel injection quantity and the time-dependent variation of the pressure of the pressure-elevated fuel.

By setting a switching timing of switching means that connects either one of a high pressure fuel source and a low pressure fuel source to an injector earlier than a point of time when an injector finishes a high pressure fuel injection, leak fuel or return fuel is reduced and an engine load is reduced and therefore mileage is improved.

Fuel injection apparatus of engine

A common-rail injection system includes a first accumulator of high pressure and a second accumulator of low pressure. The common-rail injection system includes a post injection control device for injecting additional low-pressure fuel from the second accumulator through a fuel injection nozzle after main fuel is injected. The post injection control device injects the additional fuel the injection terminates at a first timing when the fuel pressure in either fuel passage or second accumulator lowers to a predetermined value lower than that of the high-pressure fuel or at a second timing when an exhaust stroke of the engine is completed, whichever earlier.

Accumulator type fuel injection apparatus

In a common rail system comprised of a first accumulator storing high-pressure fuel and a second accumulator storing low-pressure fuel, additional fuel is injected when a fuel pressure in a fuel passage or in the second accumulator (low inlet pressure of an injector) is reduced to a low pressure approximate to the pressure of the low-pressure fuel stored in the second accumulator after a switching valve is operated for disconnection from the fuel passage (switching valve drive signal OFF) at a point in time when a main injection control device finishes the injection of fuel (injector drive signal OFF) or after the main injection control device finishes the injection of fuel. This keeps the fuel pressure as low as possible during post injection to prevent the fuel from adhering to the wall surfaces of cylinder liners.

Accumulator fuel injection system

A controller ( ) of an accumulator fuel-injection apparatus opens a selector valve ( ) for injection rate switching for a short time between auxiliary injection and main injection, the selector valve controlling high-pressure fuel supply from a high-pressure accumulator ( ) to a fuel passage ( ) on the downstream side of a check valve ( ), whereby a fuel pressure higher than an auxiliary injection pressure and lower than a main injection pressure is formed in the fuel passage on the downstream side of the selector valve ( ). By opening, in this state, an on-off valve ( ) for injection timing control to start the main injection, a proper pressure higher than the auxiliary injection pressure and lower than the subsequent main injection pressure is established in the initial stage of main injection, improving fuel economy and exhaust-gas characteristic.

Accumulator fuel-injection apparatus

An accumulator fuel injection system for controlling an injection rate according to the operating state of an engine comprises: a first accumulation chamber for containing high-pressure fuel supplied by a fuel supply pump a first electromagnetic valve device provided in a fuel passage which connects the first accumulation chamber with a fuel injection valve the first electromagnetic valve switching the fuel passage between a connected state or a disconnected state; a branch passage branched from the fuel passage at downstream side of the first electromagnetic device the branch passage having sufficiently lower constant fuel pressure than fuel pressure in the first accumulation chamber and a second electromagnetic valve device provided in a fuel return passage connecting the fuel injection valve with a fuel tank the second electromagnetic valve device switching fuel, which is injected from the fuel injection valve between an injected state and an uninjected state; and control means for opening the first electromagnetic valve device prior to the opening of the second electromagnetic valve device and then opening the second electromagnetic valve device

A fuel injector to be used with a low-pressure fuel source and a high-pressure fuel source to provide a two-stage fuel injection has superior responsiveness of fuel pressure control and ease of mounting to an engine. The fuel injector has a housing mounted to a cylinder head of an engine; a fuel injection valve fitted in a first end of the housing and having a first control valve for controlling injection of fuel to a combustion chamber of the engine; a first conduit formed in the housing and having one end connecting with the fuel injection valve and its other end opening in a second end of the housing and connected to a high-pressure fuel source storing high-pressure fuel; a second control valve, fitted to the housing, for controlling a supply of high-pressure fuel to the fuel injection valve by opening and closing the first conduit; a second conduit formed in the housing and having one end connecting with the first conduit downstream of the second control valve and its other end opening in the housing and connected to a low-pressure fuel source storing low-pressure fuel at a low-pressure than the fuel pressure of the high-pressure fuel source; and a check valve fitted in the housing and being disposed to the second conduit, for allowing the inflow of low-pressure fuel from the low-pressure fuel source to the first conduit side. As a result, the dead volume between the second control valve, the check valve and the fuel injection valve is minimized and the responsiveness of fuel pressure control can be improved.

Growing community of inventors

Tokyo, Japan

Keiki Tanabe