Multi-cylinder internal combustion engine with a system for variable actuation of the intake valves and an injector housing having a raised sealing edge

Abstract

In a multi-cylinder internal combustion engine, provided with a system for variable actuation of the intake valves of the engine, the fuel injector associated to each engine cylinder is surrounded by a sealing casing which is part of a support body. The support body is mounted on the engine cylinder head with the interposition of a support surmounting the head and defining the seat in which the camshaft is received and it defines a sealing peripheral edge cooperating with a sealing cover which is mounted on the cylinder head. The cover has a general base plane sealingly mounted on the cylinder head or on the support. The sealing peripheral edge of each sealing casing is arranged in a parallel plane and raised with respect to the general base plane of the cover.

1 . Multi-cylinder internal combustion engine, comprising, for each cylinder:
 a fuel injector,   at least one intake valve and at least one exhaust valve for each cylinder, each provided with respective return spring means which push the valve towards a closed position, for controlling respective intake and exhaust conduits,   at least one camshaft, for actuating the intake valves of the engine cylinders by means of respective tappets,   wherein each intake valve is controlled by the respective tappet, against the action of the aforementioned return spring means, by interposing hydraulic means including a pressurised fluid chamber and a hydraulic actuator associated to each intake valve and connected to said pressurised fluid chamber,   said pressurised fluid chamber being adapted to be connected by means of a solenoid valve with an exhaust channel with the aim of decoupling the intake valve from the respective tappet and causing the quick closure of the valve due to the respective return spring means,   said hydraulic actuator further being provided with hydraulic braking means for slowing the final phase of the travel for closing the intake valve controlled thereby when the pressure chamber is connected to the exhaust channel,   electronic control means for controlling each solenoid valve so as to vary the time and/or the opening travel of the respective intake valve as a function of one or more engine operative parameters,   wherein the hydraulic means for controlling the intake valves of the engine and the solenoid valves associated thereto are part of a preassembled unit mounted on the cylinder head of the engine,   characterised in that the fuel injector associated to each engine cylinder is surrounded by a sealing casing which is part of a support body mounted on the engine cylinder head and which defines a sealing peripheral edge cooperating with a sealing cover which is mounted on said cylinder head, said cover having a general base plane sealingly mounted on said cylinder head, and in that   said sealing peripheral edge of each sealing casing is arranged in a plane parallel and raised with respect to the general base plane of said cover.   
     
     
         2 . Engine according to  claim 1 , wherein said preassembled unit is formed by a plurality of separate sub-units respectively associated to the engine cylinders and each having an independent support body, mounted on the cylinder head and carrying said hydraulic means and said solenoid valve for controlling the intake valves of the respective cylinder, and in that the sealing casing of each injector is part of the support body of the sub-unit associated to the respective cylinder. 
     
     
         3 . Engine according to  claim 1 , wherein the sealing casing of each injector is part of a single support body common for all the engine cylinders and which is mounted on the cylinder head so as to close at the upper part the seat in which said camshaft is received. 
     
     
         4 . Engine according to  claim 3 , wherein the common support is mounted on the cylinder head with the interposition of a support surmounting the head and defining the seat in which said camshaft is received. 
     
     
         5 . Engine according to  claim 2 , wherein the abovementioned cover covers said pre-assembled unit and it has a base peripheral edge having a perimeter groove for mounting a sealing gasket,
 and wherein said sealing gasket has a main portion extending in a general base plane of the cover and respective portions associated to said sub-units and projecting from said general plane, in positions arranged longitudinally adjacent to each other on one side of the cylinder head and each having a three-dimensional development, with two lateral parts contained in two planes substantially parallel to each other and orthogonal to said general plane and a central part contained in a parallel plane and spaced from said base plane.   
     
     
         6 . Engine according to  claim 1 , wherein each injector is locked on the cylinder head by means of a bracket which has an end resting on a support fixed to the cylinder head and the opposite fork-shaped end, with two branches which are engaged on two shoulders of the body of the injector, the intermediate portion of said bracket being pressed in position by means of a screw which engages the cylinder head.