Abstract: Obtaining a piston blank by forging a mass of metal. The metal mass is forged in a hollow anvil using a punch to chase said metal mass into an annular zone thereof while also forming a projection that projects from the center of a base, the punch including an open cavity suitable for giving rise to said projection. The projection is subsequently machined so as to include a bore suitable for receiving a hinge pin for a connecting rod.

Abstract: The invention provides a device for eliminating cavitation in the excess fuel return orifice(s) in the compression chamber of a fuel injection pump of an internal combustion engine after the end of the injection stage, said injection pump being connected firstly to a feed duct including a first check valve having low headloss enabling fuel to reach the compression chamber, and secondly to an excess fuel return duct,wherein the return duct comprises in parallel and close to the return orifice of the injection pump, a second check valve that is rated to cause the pressure in said return orifice of the injection pump to rise, and a two-port valve that is normally open and that is caused to close by the appearance of pressure in the return orifice greater than the pressure which obtains in the feed duct upstream from said first check valve.

Abstract: Apparatus for detecting degradation of the lubrication conditions of smooth bearings connecting a crank shaft to a connecting rod or connecting the crank shaft to the body of a machine that reciprocates in operation, lubrication being provided by oil circulation, the apparatus including means for detecting the phenomenon of seizure, wherein the apparatus comprises an additional bearing serving as a test bearing, said test bearing being lubricated by circulation of the same oil as is used for the other bearings and supporting a radially-loaded rotating shaft, said detection means being fitted to the test bearing which also includes means enabling it to be more sensitive than the other bearings to degraded lubrication conditions.

Abstract: A fuel injection method for diesel internal combustion engines uses main injection of a gas main fuel and pilot injection of a liquid secondary fuel to initialize combustion of the main fuel. The liquid fuel is injected by an injector pump designed to enable the engine to achieve its maximum power with the liquid fuel only. The pilot injection comprises a mixture of water and liquid fuel.

Abstract: A fuel injection device for an internal combustion engine, in particular a diesel engine, the device is of the type comprising two spray heads, one spray head serving for pre-injection of fuel while the other serves for main injection of fuel, said spray heads being situated close to each other in the vicinity of the middle of the cylinder head. The pre-injection spray head includes a series of holes whose axes lie on a frist cone and the main injection spray head inlcudes a series of holes whose axes lie on a second cone, there being twice as many holes in the main spray head as in the pre-injection spray head, the relative positions of the cones, the angle of each of the cones, and the directions of the axes of the holes around the cones being selected in such a manner that the distances between each pre-injection jet and the two adjacent main injection jets are at a minimum and are substantially equal in a zone which is situated substantially halfway along the main injection jets.

Abstract: In a method of monitoring the emission of nitrogen oxides NO.sub.x in the exhaust gas of an internal combustion engine, the engine to be monitored incorporates an accelerometer used as a sensor. The signals produced by the accelerometer are analyzed to determine the NO.sub.x concentration in the engine exhaust gas by comparison with data supplied by an accelerometer fitted to a control engine.

Abstract: An internal combustion engine for propelling ships that transport gaseous fuel, the engine comprising two groups of cylinders, a first group which is always fed with the same fuel, and a second group which is fed selectively either with said same fuel or else with a different fuel. The invention is applicable to methane tankers.