Gas injection system, particularly of methane, for internal combustion engines, and pressure regulating valve comprised in said system

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 distributing manifold, or rail, communicating with said injectors,
• a reservoir feeding the distributing manifold, wherein the pressurized gas is accumulated,
• pressure regulating valve interposed in the connection between the reservoir and siad distributing manifold, and
• an electronic control unit set up to control the injectors and to control the opening time to meter the amount of gas injected in each cylinder according to the operating conditions of the engine,
• wherein said system also comprises means for regulating the pressure of the gas in the distributing manifold,
• wherein said regulation means are set up to regulate the pressure in the distributing manifold according to the conditions of operation of the engine, and
• wherein said regulation means comprise:
• an electromagnetic actuator controlling said pressure regulating valve,
• a sensor of the pressure in the distributing manifold, suitable for sending an electrical signal indicative of said pressure to the electronic control unit,
• a sensor of the pressure in the gas feeding line between the reservoir and the pressure regulating valve, suitable for sending an electrical signal indicative of said pressure to the electronic control unit,
• memory means associated to said electronic control unit containing maps of the theoretical predetermined pressure values to be created in the distributing manifold according to the variation of the parameters of operation of the engine,
• said electronic control unit being programmed to control the electromagnetic actuator of the pressure regulating valve according to the signals output by the sensors of the pressure in the distributing manifold and of the pressure in the line upstream to the pressure regulating valve, in order to obtain a pressure in the distributing manifold which is essentially equal to the theoretical predetermined value that the control unit retrieves in said memory means according to the value of one or more parameters of operation of the engine.