摘要:
A fuel injector (1) for an internal-combustion engine has a shell (2) provided with two opposite terminal portions; the first terminal portion (4) has an inlet (7) for supply of the fuel and is generally designed to extend outside the engine, whilst the second terminal portion (5) has a nozzle (9) communicating with said inlet (7), is designed to be housed in the engine and has, in the radial direction, dimensions smaller than those of the first portion (4); the injector (1) further has an actuator (16) and a servo valve (15) housed in the first terminal portion (4); the servo valve (15) is provided with an open/close element (32), which can slide axially, under the action of the actuator (16) and substantially in a fluid-tight way, in a seat (27) and is subjected to an axial resultant of pressure of the fuel that is substantially zero; the fuel inlet (7) is made laterally in an intermediate axial position between the actuator (16) and the nozzle (9).
摘要:
A method is provided for controlling fuel injection in an internal-combustion engine provided with an electroinjector, including an electroactuator, an injection nozzle, and a pin, which is movable along an opening stroke and a closing stroke for opening/closing the nozzle under the control of the electroactuator and according to the supply pressure of the fuel into the electroinjector. The method supplies to the electroactuator a first electrical command and at least a second electrical command, which are sufficiently close to one another as to displace the pin with a profile of motion without any discontinuity in time, and such as to cause the pin to perform a first opening displacement and, respectively, a second opening displacement. Between one injection and the next, at least one among the following quantities is varied as a function of operating parameters of the engine: duration of at least one among the electrical commands; number of the electrical commands; and distance in time between the electrical commands.
摘要:
The injection system (1) comprises a pump (7) designed to send fuel at high pressure to an accumulation volume, for example formed by a common rail (6), for supplying a plurality of injectors (5). The pump (7) comprises at least one pumping element (18) actuated with reciprocating motion with a compression stroke (Pi-Ps) at a sinusoidal speed (24), in synchronism with each step of fuel injection. The injection system (1) comprises at least one by-pass solenoid valve (14), which is controlled by a chopper control unit (16, 28) for modulating the delivery of the pumping element (18) by varying both the instant of start (To) and the instant of end (T1) of delivery during the compression stroke (Pi-Ps), in such a way that the delivery is synchronous with the injection phase.
摘要:
In a gas-supply system for internal-combustion engines, a pressure-reducing valve is set between the reservoir of the gas and a distribution manifold or rail that feeds the gas to a series of electromagnetically controlled injectors associated to the various cylinders of the engine. The pressure-reducing valve brings about a pressure drop which depends upon a pilot-pressure signal that is sent thereto by a pilot solenoid valve. The electrical supply to the solenoid of said pilot solenoid valve is controlled by an electronic control unit according to the signal issued by a sensor of the pressure in the rail for the purpose of regulating the pressure in the rail at a desired level, according to the operating conditions of the engine.
摘要:
In a gas-supply system for internal-combustion engines, a pressure-reducing valve is set between the reservoir of the gas and a distribution manifold or rail that feeds the gas to a series of electromagnetically controlled injectors associated to the various cylinders of the engine. The pressure-reducing valve has a piston member that faces a chamber set downstream of a restricted passage defined inside the body of the valve in communication between the inlet connector and the outlet connector. The piston member is pushed by thrust means towards a position in which it causes opening of an open/close element that controls the communication between said restricted passage and the inlet connector. The piston member is preferably provided with a single seal gasket that prevents leakage of gas towards the outside through the sliding coupling of the piston member within the respective guide bushing. The thrust means to which the piston member is subject may be constituted by spring means, or else by a pilot-pressure signal, in the case where it is intended to obtain a variable reduction of the pressure according to the operating conditions of the system.
摘要:
A method of producing fuel injectors for internal combustion engines provides for establishing a working life of each injector conforming with the working life of the internal combustion engine on which it is installed. Each injector has an injector body having a seat; a valve body housed inside the seat so as to form an annular chamber, for receiving high-pressure fuel, and a gap communicating with the annular chamber; and a seal housed inside the annular chamber to seal the gap. The seal is sized as a function of the permanent deformation to which the seal is subjected during use of the injector, so as to achieve a working life of the injector substantially equal to the working life of the engine.
摘要:
A safety valve for pressurized tanks, particularly for tanks for containing methane or LPG for motor vehicles, comprises an open/close element that is kept by elastic means in a closing position, in which it does not enable communication of the internal cavity of the tank with the external atmosphere. When a pre-set maximum value of the pressure inside the tank is exceeded, sufficient for overcoming the load of said elastic means, the open/close element is displaced from its closing position and enables discharge of the gas contained in the tank into the external atmosphere. The elastic means are arranged in series with a fuse element, which is set between the open/close element and the valve body. In this way, whenever the temperature -exceeds a pre-set maximum value, the fuse element melts, causing unloading of said elastic means, which consequently leaves the open/close element free to open. Preferably, associated to the open/close element are sensor means for detecting the displacement of the open/close element from its closing position, which are designed to signal intervention of the safety valve to the driver.
摘要:
The system has a high-pressure pump having a number of mechanical pumping elements for pumping high-pressure fuel to a common rail; and a number of injectors communicating with the rail and activated to inject a quantity of fuel sequentially into the corresponding cylinders of the engine. Each pumping element has a delivery at least equal to the maximum draw of each injector, and is activated in phase with at least one of the injectors to minimize the variations in fuel pressure in the rail. Each pumping element may be activated by a cam, which may even have a segmented profile to effect a portion of the travel of the respective pumping element in phase with a corresponding injector.
摘要:
On-off valve intended to be arranged at the outlet of the gas accumulation reservoir in an electronic gas injection system for an internal combustion engine, presenting a valve member made of metallic material, co-operating with a valve seat made in a body, which is also made of metallic material, to ensure the good quality of tightness in all operative temperature and pressure conditions, with prolonged reliability in time.
摘要:
Gas injection system, particularly of methane, for an internal combustion engine, comprising a plurality of electromagnetically controlled injectors associated to the various cylinders of the engine, a gas distributing manifold communicating with the injectors, a reservoir feeding the distributing manifold, where the pressurised gas is accumulated. A pressure regulating valve is interposed in the connection between the reservoir and is controlled by an electronic control unit so to vary the pressure of the gas in the distributing manifold according to the signals output by sensors of the pressure in the distributing manifold and in the line feeding the gas from the reservoir, also to obtain a pressure in the distributing manifold which is essentially equal to a prefixed theoretical value that the control unit detects according to one or more operative parameters of the engine on the basis of prefixed theoretical pressure values of the pressure stored in maps to be obtained in the distribution manifold as the conditions of operation of the engine vary.