EP3999734A1

EP3999734A1 - Hydraulic cam injection system

Info

Publication number: EP3999734A1
Application number: EP20754324.0A
Authority: EP
Inventors: Vianney Rabhi
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-18
Filing date: 2020-07-16
Publication date: 2022-05-25
Also published as: FR3098858B1; FR3098857B1; KR20220034796A; FR3098857A1; AU2020315180A1; FR3098858A1; WO2021009466A1; CA3144505A1; JP2022541109A; FR3098868B1; CN114051554A; FR3098868A1

Abstract

The hydraulic cam injection system (100) comprises an injection valve (50) housed in a tubular injection nozzle (54), a gap being left between a valve stem (51) of the valve (50) and the inner surface of the tubular injection nozzle (54) to allow an injectable fluid (58) to flow from pressurising means (10) while a receiving piston (62) rigidly connected to the valve (50) receives, on the one hand, the pressure of the injectable fluid (58) to keep the valve (50) closed, and on the other hand, the pressure of a hydraulic fluid (60) to open the valve (50), an injection cam (67) being capable of moving the receiving piston (62) by means of a transmitting piston (69) and the hydraulic fluid (60).

Description

Title of the invention: HYDRAULIC INJECTION SYSTEM

A CAME

The present invention relates to a hydraulic cam injection system provided inter alia for injecting a pilot charge consisting of a mixture of air and easily flammable fuel in a valve ignition prechamber or, more incidentally , in a prechamber formed by a shuttle electrode spark plug.

[0002] When said pilot charge is ignited by a spark, said prechamber ejects hot gas torches into the combustion chamber of an internal combustion heat engine in order to ignite a main charge contained in said chamber.

We know the French patent application N FR 17 50264 of January 12, 2017 relating to a valve ignition prechamber, published on July 13, 2018 under the No. 3,061,743. We also know the French patent relating to a shuttle electrode spark plug published on May 17, 2019 under number 3 060 222. The two said requests belong to the applicant.

[0004] Said application and said patent have commonly been the subject of two French improvement patent applications which also belong to the applicant. The first said request dated September 10, 2018 was registered under

No. 18 58111 and relates to a magnetic valve return device. The second said request was registered on May 13, 2019 under number 1904961 and concerns an ignition insert with active prechamber.

[0005] The inventions relating to the aforementioned patent applications and patents apply primarily to any spark-ignition reciprocating engine of any type whatsoever, the main charge of which is greatly diluted with fresh air or with exhaust gases recirculated previously cooled.

[0006] Subject to stable, rapid and sufficiently complete combustion, said

The highly diluted main charge increases the average and / or maximum thermodynamic efficiency of said engine which receives it compared to that of engines with ignition by spark plug only and therefore, reduces the fuel consumption of said engine at the same work produced.

[0007] It is to meet this objective of stable, rapid combustion, and sufficiently

complete that said inventions are intended to produce a powerful, stable and safe ignition without which the expected reduction in fuel consumption cannot be obtained. We see that the inventions relating to the patent and patent applications which have just been cited require an injector which directly injects into the prechamber a mixture of air and fuel, the latter having been previously pressurized by a compressor .

Note that said injector must be as compact as possible to be able to be integrated into the cylinder head of any spark ignition reciprocating engine without unduly interfering with the intake ducts, with the exhaust ducts, or with the chambers of cooling water included in said cylinder head.

[0010] Besides being compact, we see on reading the French patent application

N 1904961 that said injector should advantageously have a nozzle of great length and small diameter. This particular configuration is necessary so that said injector can be integrated into the cylinder head of any reciprocating internal combustion engine with spark ignition without interfering in a crippling manner with the components and functional volumes of said cylinder head. This implies in particular providing an injector provided with a very long needle, the high mass of which requires a powerful actuator.

[0011] The injector in question must also offer high dynamics and high permeability. These qualities are necessary to be able to inject the pilot charge into the prechamber within the allotted time, regardless of the speed and load of the internal combustion engine, and despite a relatively expected pressure of the air and fuel mixture. low at the inlet of said injector.

[0012] Because, in fact, reciprocating spark-ignition internal combustion engines are mostly cooled by a water circuit, the temperature of which is maintained around one hundred degrees Celsius. It follows from this that preferably, G injector of air and fuel mixture provided for in the inventions of French patent application No. FR 17 50264 and French patent No. 3 060 222 must also be maintained at a temperature n ' not exceeding one hundred degrees Celsius, in order to avoid any additional device for heating said injector.

[0013] However, by way of non-limiting example, if the temperature of the injector does not exceed one hundred degrees Celsius and if the richness of the air-gasoline mixture that it injects is 1.2 or 1.3 , the pressure of said mixture at the inlet of said injector must not exceed fifty bars.

[0014] Indeed, beyond this limit pressure, part of the fuel contained in the mixture would condense on the internal walls of the injector and would pass from the gaseous state to the liquid state. As a consequence of exceeding this limit saturated vapor pressure, the fraction of the pilot charge remaining in the gaseous state would be of less richness, would possibly be difficult to ignite, and its combustion would be potentially unstable. In addition, the highly reactive chemical species which result from the combustion of a rich mixture would no longer be produced in the quantities re- sought, and the torch ignition of the main charge would become less efficient.

[0015] Taking into account what has just been said, in order to be able to inject an air-gasoline mixture of 1.2 to 1.3 richness maintained at one hundred degrees Celsius, it is not necessary that the pressure at the inlet of the injector which is responsible for injecting the pilot charge into the prechamber described in French patent application No. FR 17 50264 and in French patent No. 3 060 222 exceeds fifty bars. This relatively low pressure must be compensated by a high permeability to the injector.

[0016] To obtain said high permeability, it is not possible to increase exa

manage the diameter of the injector because it would become too bulky. The most suitable solution is to significantly increase the stroke of the injector needle, compared to that of a direct automotive gasoline injector which is of the order of fifty to sixty micrometers.

The problem is that increasing the needle stroke requires more than proportionally increasing the size and power of the solenoid actuator that moves said needle. In fact, raising the needle more within the same time period increases the average speed of lifting and resting said needle. This increase in lift and rest speed has more impact on the sizing of the solenoid actuator as the reciprocating internal combustion engine itself is running at high speed.

[0018] In addition, an increased stroke of said needle moves away the solenoid pallet which actuates said needle from the stator with which said pallet cooperates. As the force exerted by said vane on said needle decreases approximately due to the square of the distance between said vane from said stator, the constituent coil of the solenoid actuator must produce a very strong magnetic field. This is all the more true as the needle moves away strongly from its seat, it is necessary to provide a powerful return spring, capable of returning said needle to its seat within the allotted time.

[0019] Increasing the stroke of the needle therefore leads to an actuator coil whose need for electric current penalizes the efficiency of the internal combustion engine, and whose size and weight are hardly compatible with the space available in the cylinder head of said engine. In addition, the cost price of such a coil

actuator will potentially be incompatible with the economic constraints of mass production automobile production.

[0020] In addition, the high speeds at which said needle rests on its seat would produce an excessive power shock which would compromise the durability of said needle and of said seat. The damage caused by said impact would be all the greater if the injector injects a gas mixture of low density, the lubricating properties of which are practically non-existent. It is to solve these various problems that the hydraulic cam injection system according to the invention, in connection with the inventions of French patent application No. FR 17 50264 and French patent No. 3 060 222 and according to a particular embodiment, allows:

• To produce a pilot charge injector with a nozzle of great length and small diameter, easily integrated into the cylinder head of a reciprocating internal combustion engine;

• To provide a large injector needle lift which gives the pilot charge injector and despite its small diameter a passage section and a permeability of several tens of times greater than that of a direct gasoline injector. conventional, so that said pilot charge injector ensures the filling of the prechamber over the entire operating range of the reciprocating internal combustion engine despite a limited pressure - for example at fifty bars - of the air and fuel mixture at the inlet of said injector;

• To produce a long-life pilot charge injector despite a large needle lift and despite the said injector injecting a low density gas mixture with virtually non-existent lubricating properties;

• To produce a pilot charge injector, the cost price of which is notably compatible with large-scale automobile production;

• To drastically reduce the weight and bulk of the actuator which moves the needle of the pilot charge injector, so that said actuator is easily housed inside or near the cylinder head of any reciprocating engine. internal combustion.

[0022] The applications of the hydraulic cam injection system according to the invention are moreover not limited to the only inventions relating to French patent application N FR 17 50264 and to French patent N ° 3,060,222.

[0023] The hydraulic cam injection system according to the invention can in particular

inject gas or liquid into any active prechamber with or without valve, or replace any direct or indirect injector according to the state of the art injecting a gas and / or a pure or compound liquid, whether said injector is put into operation work in a heat engine of any type, or in any other machine with no application limit.

[0024] The hydraulic cam injection system comprises:

• At least one injection valve which comprises a valve stem and which ends in a tulip, the latter exposing a valve sealing surface, said valve being wholly or partly housed in a tubular injection nozzle terminated by an injection valve seat on which the valve sealing face can sealingly rest while a space is left between the valve stem and the internal surface of the tubular injection nozzle to let circulate an injectable fluid pressurized by pressurizing means;

• At least one nozzle inlet opening in the injection nozzle

tubular and through which the injectable fluid is introduced inside said nozzle;

• At least one slave cylinder which is directly or indirectly integral with the end of the tubular injection nozzle;

• At least one receiving piston integral with the valve stem and housed in the receiving cylinder, said piston being able to move in longitudinal translation in said cylinder and having an axial face on the injectable fluid side which communicates with the internal volume of the nozzle. tubular injection, and an axial face on the hydraulic fluid side which forms, with the receiving cylinder, a receiving chamber of variable volume filled with hydraulic fluid;

• At least one hydraulic fluid supply device connected to the receiving chamber and which makes it possible to actuate the receiving piston via the hydraulic fluid through a hydraulic action line.

[0025] The hydraulic cam injection system according to the present invention comprises a receiving piston return spring which tends to move the receiving piston closer to a receiving cylinder head.

The hydraulic cam injection system according to the present invention comprises permeable guide means which are directly or indirectly integral with the injection valve and / or the tubular injection nozzle, said means keeping the valve d injection approximately centered in the tubular injection nozzle.

The hydraulic cam injection system according to the present invention comprises a hydraulic fluid supply device which consists of an injection cam which has at least one cam profile maintained directly or indirectly in contact with an axial action face presented by a sender piston housed in a sender cylinder, said piston having - opposite the axial action face - an axial hydraulic fluid emission face which forms an emitter chamber with the cylinder transmitter however that the cam profile can move the transmitter piston in longitudinal translation in the transmitter cylinder when the injection cam is rotated by a driving source.

[0028] The hydraulic cam injection system according to the present invention comprises a hydraulic action conduit which connects the emitting chamber to the receiving chamber, said conduit, the emitting chamber and the receiving chamber being filled with hydraulic fluid.

The hydraulic cam injection system according to the present invention comprises a the cam profile which comprises at least one angular lift sector which moves the emitter piston when said sector is in contact with the axial action face and the injection cam is rotating, and at least one angular sector of circular maintenance and centered on the axis of rotation of said injection cam which immobilizes the emitter piston when said sector is in contact with the axial action face and this despite the injection cam being in rotation.

The hydraulic cam injection system according to the present invention comprises a cam profile which is maintained in contact with the axial action face by means of a rocker arm which directly or indirectly bears on a housing of cam in which the injection cam rotates.

The hydraulic cam injection system according to the present invention comprises a rocker arm which bears on the cam housing by means of a movable tipping point whose position between the cam profile and the axial face of The action can be changed by an injector lift actuator.

The hydraulic cam injection system according to the present invention comprises a movable tipping point which consists of a movable support roller which can roll or slide on a movement track provided in the cam housing, said roller cooperating with a tilting track arranged at the back of the rocker.

[0033] The hydraulic cam injection system according to the present invention comprises a movable support roller receives at each of its ends a pinion

orientation, said pinions being integral in rotation, while each said pinion cooperates with an orientation rack integral with the cam housing.

The hydraulic cam injection system according to the present invention comprises a movable support roller which receives a worm wheel which cooperates with a worm whose axial position is fixed relative to the cam housing, said screw being able to be driven in rotation by G injector lift actuator.

The hydraulic cam injection system according to the present invention comprises a movable support roller which receives a thread in which G injector lift actuator can rotate a displacement screw which is integral in position of the housing. cam but free to rotate around its longitudinal axis.

[0036] The hydraulic cam injection system according to the present invention comprises an injection cam phase shifter which is interposed between the injection cam and the driving source.

[0037] The hydraulic cam injection system according to the present invention comprises a tubular injection nozzle, the end of which ends with the injection valve seat is capped with a diffuser with holes.

The hydraulic cam injection system according to the present invention comprises a diffuser with holes, at least part of its internal wall of which is cylindrical and leaves a small clearance between itself and the external peripheral surface of the tulip so that said diffuser forms the permeable guide means.

The hydraulic cam injection system according to the present invention comprises a booster pump which tends to introduce hydraulic fluid into the hydraulic action duct via a booster non-return valve, said hydraulic fluid coming from a hydraulic fluid tank.

The hydraulic cam injection system according to the present invention comprises at least one drainage orifice which is connected to a drainage duct and which opens into the receiving cylinder, the axial face on the injectable fluid side and the axial face on the fluid side. hydraulic always remaining axially positioned on either side of said orifice whatever the position of the receiving piston.

[0041] The hydraulic cam injection system according to the present invention comprises a receiving piston which has a drainage groove which communicates with the drainage port.

The hydraulic cam injection system according to the present invention comprises a receiving piston which consists of a first body which receives the axial face on the injectable fluid side and which is integral with the valve stem, and of a second body which may or may not be integral with said first body and which receives the axial face on the hydraulic fluid side, an external shoulder arranged on one, the other or both of said bodies forming the drainage groove.

The hydraulic cam injection system according to the present invention comprises a maximum range of displacement of the tilting point movable between the cam profile and the axial action face which is determined by at least one end stop .

[0044] The hydraulic cam injection system according to the present invention comprises a displacement track which is secured to the cam housing by means of at least one track orienting ball.

The hydraulic cam injection system according to the present invention comprises a receiving piston which consists of at least a first body which receives the axial face on the injectable fluid side and which is integral with the valve stem, and of at least one second body, whether or not integral with said first body and which receives the axial face on the hydraulic fluid side.

The hydraulic cam injection system according to the present invention comprises a receiving piston which comprises an external shoulder arranged on one, the other or both bodies, said shoulder forming a drainage groove which communicates with at least a drainage orifice which is provided in the receiving cylinder and which is connected to a drainage duct. The description which will follow with reference to the accompanying drawings and given by way of non-limiting examples will make it possible to better understand the invention, the characteristics that it presents, and the advantages that it is likely to provide:

[0048] [fig.l] is a schematic sectional view of the hydraulic cam injection system according to the invention as it can be installed in the cylinder head of an internal combustion engine equipped with a prechamber of valve ignition according to French patent application N ° FR 17 50264, and an active prechamber ignition insert according to French patent application N 3 060 222.

[0049] [fig.2] is a schematic sectional view which shows the angular lifting and holding sectors as can be accommodated by the cam profile of the hydraulic cam injection system according to the invention.

[0050] [Fig. 3 to 5] are schematic sectional views illustrating the operation of the injection cam and of the sender piston of the hydraulic cam injection system according to the invention, said cam cooperating with a rocker arm, the lever arm of which can vary by function of the position of a displaceable support roller, said position being controlled by an electric stepper motor via a worm and a worm wheel.

[0051] [Fig.6] is a three-dimensional view of the injection cam of the hydraulic cam injection system according to the invention, and of the main functional components shown in Figures 3 to 5 with which said cam cooperates.

[0052] [fig.7] is a three-dimensional view of the tubular injection nozzle of the system

hydraulic injection cam according to the invention, and the main components that it houses or with which it cooperates.

[0053] [Fig.8] is a three-dimensional sectional view of the tubular injection nozzle of the hydraulic cam injection system according to the invention, and of the main components that it houses or with which it cooperates.

[0054] [Fig.9] is a three-dimensional view of the injection valve of the hydraulic cam injection system according to the invention, equipped with the receiving piston and the receiving piston return spring.

[0055] [Fig.10] is a three-dimensional view of the hole diffuser as it may be provided to complete the tubular injection nozzle of the hydraulic cam injection system according to the invention.

[0056] [fig.l 1] is a schematic sectional view of the tubular injection nozzle of the hydraulic cam injection system according to the invention and of the main components that it hosts or with which it cooperates, such as 'it can be installed in the cylinder head of an internal combustion engine equipped with a valve pre-chamber according to French patent application No. FR 17 50264, and an ignition insert with active pre-chamber according to French patent application N 3 060 222. [0057] [fig.12] is a three-dimensional phantom view of the injection cam of the hydraulic cam injection system according to the invention, the displaceable support roller of which receives a thread in which the lifting actuator of injector can rotate a displacement screw.

[0058] DESCRIPTION OF THE INVENTION

[0059] There is shown in Figures 1 to 12 the hydraulic cam injection system 100 according to the invention, various details of its components, its variants, and its accessories.

[0060] As shown in Figure 1 and Figures 7 to 11, the hy injection system

Hydraulic cam 100 includes at least one injection valve 50 which includes a valve stem 51, and which terminates in a tulip 52 which exposes a valve seal face 53.

Note in Figure 1 and Figures 7 to 11 that the valve 50 is fully or partially housed in a tubular injection nozzle 54 terminated by an injection valve seat 55 on which the valve sealing face 53, while a space is left between the valve stem 51 and the internal surface of the tubular injection nozzle 54 to allow an injectable fluid 58 to circulate under pressure by pressurizing means 10. It should also be noted that according to a particular embodiment of the hydraulic cam injection system according to the invention, the valve sealing surface 53 may be frustoconical while the injection valve seat 55 is conical. .

In Figures 8, 9, 10 and 11, we note that the hydraulic cam injection system 100 provides permeable guide means 56 which are directly or indirectly integral with the injection valve 50 and / or the tubular injection nozzle 54. Said means 56 keep the injection valve 50 approximately centered in the tubular injection nozzle 54 regardless of the axial position of said valve 50 relative to said nozzle 54.

Note in Figures 8, 9, 10 and 11 that the permeable guide means 56

may include at least one gas passage channel 57 which allows the injectable fluid 58 to circulate between the injection valve 50 and the tubular injection nozzle 54.

In Figures 7 and 8 and 11, it is noted that the hydraulic cam injection system 100 comprises a nozzle inlet port 59 arranged in the tubular injection nozzle 54 and through which the injectable fluid 58 is introduced inside said nozzle 54 after having been conveyed by an injectable fluid supply duct 66 which connects the pressurizing means 10 to said orifice 59.

Note that the connection between the injectable fluid supply duct 66 and the nozzle inlet orifice 59 can be made by welding, crimping, by means of a "banjo" connector known per se, or by using a terminal block of any type. In addition, the injectable fluid supply duct 66 can receive heating means by electrical resistance, by external circulation of a heat transfer fluid such as water or oil, or by any other means. . Said heating means advantageously make it possible to accelerate the rise in temperature of the injectable fluid supply duct 66 when the hydraulic cam injection system 100 according to the invention is started up in a low temperature environment.

Said means or similar means can also be applied to the hydraulic action conduit 78 and / or to the tubular injection nozzle 54.

As shown in particular in Figures 8 and 11, the hydraulic cam injection system 100 comprises at least one receiver cylinder 61 which is directly or indirectly secured to the end of the tubular injection nozzle 54 which is located opposite the end of said nozzle 54 which receives the injection valve seat 55, said receiver cylinder 61 being positioned in the extension of said nozzle 54.

Also, Figures 1, 8, 9 and 11 show that the hydraulic cam injection system 100 comprises at least one receiver piston 62 integral with the valve stem 51 and housed in the receiver cylinder 61, said piston 62 able to move in longitudinal translation in said cylinder 61 and having an axial face on the injectable fluid side 63 which communicates with the internal volume of the tubular injection nozzle 54, and an axial face on the hydraulic fluid side 64 which forms, with the receiver cylinder 61 and a receiving cylinder head 74 which terminates said cylinder 61, a receiving chamber 71 of variable volume.

Note that the receiving piston 62 can be made in one or more parts, and that it can receive a seal of any type whatsoever and in particular, a composite seal having a low coefficient of friction and a high abrasion resistance. This particular configuration can also be applied to the emitter piston 69.

In Figures 1 to 6 and in Figure 12, it is noted that the hydraulic cam injection system 100 comprises a hydraulic fluid supply device 65 consisting of at least one injection cam 67 which has at least a cam profile 68 maintained directly or indirectly in contact with an axial action face 75 presented by a sender piston 69 housed in a sender cylinder 70.

It is noted, particularly in Figures 3 to 6 and in Figure 12, that said piston 69 has - opposite the axial action face 75 - an axial hydraulic fluid emission face 76 which forms a emitter chamber 72 with the emitter cylinder 70 and an emitter cylinder head 77 which terminates said cylinder 70, while the cam profile 68 can move the emitter piston 69 in longitudinal translation in the emitter cylinder 70 when the injection cam 67 is activated. rotation by a motor source 73.

The driving source 73 can take the form of an electric motor, a hydraulic motor, the crankshaft of an internal combustion engine 2, or any other driving source 73 to which the injection cam 67 is connected by any type of transmission whether it is a shaft, a toothed belt or not, a chain, or pinions.

It will be noted that if the injection cam 67 is driven by the crankshaft of an internal combustion engine 2, it can be integral with the camshaft of said engine 2, or placed at the end of the central shaft of an air compressor which forms the pressurizing means 10, or receive a clean pulley which is driven by the distribution belt of said engine 2.

We see, particularly in Figure 1, that the hydraulic cam injection system 100 comprises at least one hydraulic action conduit 78 which connects the emitting chamber 72 to the receiving chamber 71, said conduit 78, the emitting chamber 72 and the receiving chamber 71 being filled with hydraulic fluid 60.

Figures 8, 9 and 11 illustrate that a receiver piston return spring 79 can be provided which tends to bring the receiver piston 62 of the receiver cylinder head 74 which has the consequence of tending to maintain the range of valve seal 53 in contact with the injection valve seat 55.

Said spring 79 may for example be housed in the receiving cylinder 61 and / or in the tubular injection nozzle 54 and be helical, formed of a stack of elastic washers or be of any type known to those skilled in the art. art. Note that a similar return spring may tend to bring the emitter piston 69 closer to the emitting cylinder head 77.

As clearly illustrated in Figure 2, the cam profile 68 may include at least one angular lift sector 15 which moves the emitter piston 69 when said sector 15 is in contact with the axial action face 75 and that the injection cam 67 is rotating, and at least one angular retaining sector 16 circular and centered on the axis of rotation of said injection cam 67 which immobilizes the emitter piston 69 when said sector 16 is in contact with the axial action face 75 and this despite the injection cam 67 being in rotation.

It will be noted that the difference in radius of the cam profile 68 between that found at the level of the angular holding sector 16 and that found at the level of the angular lift sector 15 determines the lift L produced by the injection cam 67 at the level of the cam profile 68. Taking into account any mechanical and / or hydraulic lever arms, said value L corresponds to a higher or lower lift of the injection valve 50.

As an alternative embodiment of the hydraulic cam injection system 100

according to the invention shown in Figure 1, in Figures 3 to 6, and in Figure 12, the profile of cam 68 can be kept in contact with the axial action face 75 by means of a rocker arm 80 which bears directly or indirectly on a cam housing 81 in which the injection cam 67 rotates.

It is noted in Figure 1, Figures 3 to 6, and Figure 12, that advantageously the

rocker arm 80 can be kept in contact with the cam profile 68 by

through a latch roller 86 known per se which limits friction losses at the interface between said rocker arm 80 and said cam profile 68.

It is also noted in Figure 1, in Figures 3 to 6, and in Figure 12, that according to a particular embodiment of the hydraulic cam injection system 100 according to the invention, the rocker arm 80 can be kept in contact. either of the cam profile 68 or of the axial action face 75 by a rocker arm return spring 14.

[0083] In addition, the rocker arm 80 can cooperate with guide means, not shown, arranged in the cam housing 81 so that said rocker arm 80 cannot rotate about an axis perpendicular to its operational tilting axis.

In Figure 1, Figures 3 to 6, and Figure 12, it will be noted that the rocker 80 can

resting on the cam housing 81 via a movable tipping point 82, the position of which between the cam profile 68 and the axial action face 75 can be changed by an injector lift actuator 83.

As can easily be deduced from Figure 1, Figures 3 to 6, and Figure 12, for the same cam profile 68, the position of the movable tipping point 82 determines the amplitude of displacement of the face axial action 75 and therefore the lift height of the injection valve 50 relative to the injection valve seat 55 with which it cooperates.

As a result, if the tubular injection nozzle 54 opens into a volume at

constant pressure, for a given speed of rotation of the injection cam 67 and for a given pressure of the injectable fluid 58 in the injectable fluid supply duct 66, the greater the lift height of the injection valve 50 is im load, the greater the amount of injectable fluid 58 expelled from the tubular injection nozzle 54 via the passage left between the valve sealing face 53 and the injection valve seat 55.

[0087] Figure 1, Figures 3 to 6, and Figure 12 show that advantageously, the movable tipping point 82 may consist of a movable support roller 84 which can roll or slide on a displacement track 85 arranged in the cam housing 81, said roller 84 cooperating with a tilting track 87 arranged at the back of the rocker arm 80.

It can be seen in Figure 1, Figures 3 to 6, and Figure 12, that advantageously, the rocker arm 80 can be articulated around a ball 88 integral with the axial action face 75. As a refinement, the latch roller 86 may have an outer shape in barrel. According to this particular configuration, the displacement track 85 and the tilting track 87 can be perfectly flat and the displaceable support roller 84 can be perfectly cylindrical. This non-limiting configuration makes it possible to avoid any hyperstatic relationship between the various parts 84, 85, 86, 87 which have just been listed, while avoiding having to produce a cam profile 68 whose outer axial surface is curved. .

FIG. 6 clearly shows that the movable support roller 84 can receive at each of its ends an orientation pinion 89, said pinions 89 being so lidaires in rotation, while each said pinion 89 cooperates with a rack d 'orientation 90 integral with the cam housing 81.

This particular configuration makes it possible to keep the movable support roller 84 perpendicular to the displacement track 85 with which it cooperates, and this regardless of the position of said roller 84 relative to said track 85.

Figure 6 also clearly shows that the movable support roller 84 can receive a worm wheel 91 which cooperates with a worm 92 whose axial position is fixed relative to the cam housing 81. In this case, said screw 92 can be rotated by the injector lift actuator 83 which can be, as shown in Figure 1 and Figures 3 to 6, an electric stepper motor 93 matched or not with 'a reduction gear of any type and controlled by an ECU computer.

It will be noted that the step-by-step electric motor 93, just like any injector lift actuator 83, can be connected to the worm 92 directly or by means of a transmission by belt, chain, pinions, or any type known to those skilled in the art.

Thus, when the injector lift actuator 83 rotates the worm 92, the movable support roller 84 moves relative to the displacement track 85 with which it cooperates, which has the consequence of moving the position of the movable bottom point 82 relative to the cam housing 81. This adjusts the amount of injectable fluid 58 expelled from the tubular injection nozzle 54.

It will be noted that the same movable support roller 84 can cooperate with

several rocker arms 80 to simultaneously vary the lever arm, just as a single electric stepper motor 93 can move several movable support rollers 84.

As an alternative shown in Figure 12, the movable support roller 84 can receive a thread in which the injector lift actuator 83 can rotate a displacement screw 17 which is integral in position of the housing cam 81 but free to rotate around its longitudinal axis, which has the effect of sliding the movable support roller 84 on the displacement track 85.

In Figure 1, it has been shown that an injection cam phase shifter 96 can be interposed between the injection cam 67 and the driving source 73, said phase shifter 96 making it possible to advance or angularly delay with respect to the driving source 73 the movement which the injection cam 67 impresses on the emitting piston 69, for example when said source 73 consists of the crankshaft of an engine with an internal combustion engine 2.

Note that the principle of the injection cam phase shifter 96 may be similar to that of hydraulic or electric camshaft phase shifters in automotive internal combustion engines.

In Figure 10, it has been shown that the end of the tubular injection nozzle 54 which ends with the injection valve seat 55 can be capped with a hole diffuser 94 which forces the injectable fluid 58 expelled from the tubular injection nozzle 54 via the passage left between the valve sealing face 53 and the injection valve seat 55 to pass through one or more ejection ports 95 so as to create jets of fluid injectable 58.

According to this variant of the hydraulic cam injection system 100 according to the invention, at least part of the internal wall of the diffuser with holes 94 can be cylindrical and leave a small clearance between itself and the external peripheral surface. of the tulip 52 so that said diffuser 94 forms the permeable guide means 56.

[0100] Finally, FIG. 1 shows that a booster pump 7 can be provided which tends to introduce hydraulic fluid 60 into the hydraulic action duct 78 via a booster check valve 8, said hydraulic fluid 60 from a hydraulic fluid tank 11.

[0101] It is noted that according to a particular embodiment of the injection system hy

hydraulic cam 100 according to the invention, the booster pump 7 may consist of the lubricating pump of an internal combustion engine 2 while the hydraulic fluid tank 11 consists of the oil pan of said engine 2. On note moreover that the hydraulic action conduit 78 may include a pressure limiter and purge devices known per se.

As shown in Figure 11, it is noted that the hydraulic cam injection system 100 according to the invention can receive at least one drainage orifice 97 which is connected to a drainage duct 99 and which opens into the cylinder. receiver 61. It is understood that in this case, the axial face on the injectable fluid side 63 and the axial face on the hydraulic fluid side 64 always remain axially positioned on either side of said orifice 97 regardless of the position of the receiver piston 62.

[0103] According to this particular configuration, the receiving piston 62 comprises a drainage groove 98 which communicates with the drainage orifice 97, said groove 98 collecting, on the one hand, injectable fluid 58 leaking between the receiving piston 62 and the cylinder. receiver 61 from the axial face on the injectable fluid side 63 and, on the other hand, of the hy- fluid 60 and / or air leaking between said piston 62 and said cylinder 61 from the hydraulic fluid side axial face 64, so that said injectable fluid 58, said hydraulic fluid 60 and / or said air can be exhausted via the drainage pipe 99.

[0104] It is noted that the drainage groove 98, the drainage orifice 97 and the

drainage 99 thus permanently purge the hydraulic action conduit 78 of any air prejudicial to the proper functioning of the hydraulic cam injection system 100 according to the invention.

In Figure 11, it can be seen that the receiving piston 62 may consist of a first body which receives the axial face on the injectable fluid side 63 and which is integral with the valve stem 51, and of a second integral body or not of said first body and which receives the axial face on the hydraulic fluid side 64, an external shoulder 20 arranged on one, the other or both of said bodies forming the drainage groove 98.

[0106] It is noted in FIG. 12 that the maximum range of displacement of the movable tilting point 82 between the cam profile 68 and the axial action face 75 can advantageously be determined by at least one end stop 19 which constitutes among other things a geometric reference position that can be used by the injector lift actuator 83 to reset the position of the movable tilting point 82, and to adjust the correct quantity of injectable fluid 58 expelled from the tubular injection nozzle 54 via the passage left between the valve sealing face 53 and the injection valve seat 55.

[0107] FIG. 12 also illustrates that the displacement track 85 can be made

secured to the cam housing 81 via at least one track orientation ball 18 which allows said track 85 to conform to the orientation of the rocker arm 80, said orientation being imposed by the geometric environment of said rocker 80.

It is noted, still in Figure 12, that according to an alternative embodiment of the hydraulic cam injection system 100 according to the invention, the axial position of the track orientation ball 18 in the cam housing 81 can be adjusted by means of an adjusting screw 21.

[0109] OPERATION OF THE INVENTION:

[0110] The operation of the hydraulic cam injection system 100 according to the invention is easily understood from the view of Figures 1 to 12.

[0111] To detail the operation of said system 100, we apply it here to the

valve ignition prechamber which was the subject of French patent application N ° FR 17 50264, said prechamber receiving on the one hand, the valve magnetic return device which is the subject of French patent application N ° 18 58111 , and on the other hand, the ignition insert with active prechamber which is the subject of French patent application No. 1904961.

[0112] Figures 1 and 11 show the hydraulic cam injection system 100 which according to this non-limiting example is fitted to an internal combustion engine 2 which comprises in particular a cylinder 4 topped with a cylinder head 3, said cylinder 4 and said cylinder head 3 forming, with a piston 31, a combustion chamber 5.

In Figures let 11, we note the valve ignition prechamber 1 arranged in an active prechamber ignition insert 6 housed in the cylinder head 3. It is also noted in said Figures 1 and 11 that the nozzle of tubular injection 54 and the injection valve 50 open into the valve ignition prechamber 1 in order to be able to introduce therein an injectable fluid 58 which, according to this example, consists of an AF mixture of air and gasoline easily flammable.

[0114] Said AF mixture forms a pilot charge 9 which is intended to be ignited by an ignition plug 12 which opens into the valve ignition prechamber 1. Once fired, said pilot charge 9 will be ejected. via gas ejection orifices 24 in the combustion chamber 5, in the form of high temperature gas torches. Said torches are intended to ignite a main charge 30 contained in said combustion chamber 5.

In Figures 1 and 11, it can be seen that the valve ignition prechamber 1 and the combustion chamber 5 are separated by a valve 13 which is returned to its seat by a permanent magnet 49 which is part of the control device. magnetic return valve 42 as described in French patent application No. 18 58111 belonging to the applicant. Said valve 13 allows the gases contained in the valve pre-ignition chamber 1 to enter the combustion chamber 5, but it prevents the gases contained in said chamber 5 from entering the valve ignition pre-chamber 1.

[0116] When it is closed, the valve 13 turns the valve ignition prechamber 1 into a

closed volume in which a lower pressure and temperature prevail than those prevailing in the combustion chamber 5. This eliminates any risk of self-ignition of the pilot charge 9 in said prechamber 1.

[0117] The valve 13 being closed, the tubular injection nozzle 54 can inject into the

valve pre-ignition chamber 1 the easily flammable pilot charge 9 necessary without risk of mixing the latter with the main charge 30 which, on the contrary being hardly flammable, must be brought to a higher pressure and temperature to allow and promote it inflammation.

[0118] It is noted that the particular configuration shown in Figures 1 and 11 of the

cylinder head 3 and the active prechamber ignition insert 6 requires a tubular injection nozzle 54 of great length. The latter is incompatible with the technological and manufacturing constraints of compact and economical injectors usually used in automobiles. However, said great length does not pose any particular problem if recourse is had to the hydraulic cam injection system 100 according to the invention. We will here make the assumption that the pressure of the injectable fluid 58 supplied to the tubular injection nozzle 54 by the pressurizing means 10 is fifty bars. This pressure must not be exceeded because the injectable fluid 58 consists of a gaseous mixture of air and AF gasoline. In fact, the injectable fluid 58 is maintained at a temperature of one hundred degrees Celsius. Said temperature is imposed by the water which circulates in the cooling water chambers 41 of the cylinder head 3 of the internal combustion engine 2. However, if at such a temperature the pressure of the injectable fluid 58 exceeded fifty bars, a part of the gasoline constituting the gas mixture AF would inevitably condense.

[0120] Recall that the tubular injection nozzle 54 injects the injectable fluid 58 into the valve ignition prechamber 1 to form the pilot charge 9 during the compression stroke of the internal combustion engine 2, while taking care that that the pressure in said prechamber 1 always remains lower than the pressure in combustion chamber 5.

[0121] This constraint leads to an injection time of the pilot charge 9 limited, for example, to forty degrees of crankshaft of the internal combustion engine 2.

[0122] The length, temperature and pressure constraints which have just been

described give full advantage to the hydraulic cam injection system 100 according to the invention. In fact, said system 100 makes it possible to produce a long and compact tubular injection nozzle 54, capable of injecting in less than forty degrees of shaft the pilot charge 9 required in the valve ignition prechamber 1, this despite an upstream pressure of the injectable fluid 58 limited to fifty bars due to its temperature limited to one hundred degrees Celsius.

To achieve this result, it is noted in Figures 8 and 11 that the section exposed to the pressure of the injectable fluid 58 of the axial face of the injectable fluid side 63 of the receiving piston 62 is provided larger than the section exposed by the tulip 52 of the injection valve 50 at said pressure when said valve 50 rests on the injection valve seat 55 with which it cooperates.

[0124] Consequently, the pressure which prevails in the tubular injection nozzle 54 tends to press the valve sealing surface 53 on the injection valve seat 55, and to keep the injection valve 50 closed, aided in this by the receiver piston return spring 79. This significant return force produced by the pressure of the injectable fluid 58 makes it possible to avoid having to resort to a high power receiver piston return spring 79 which would be heavy and bulky .

It will be assumed, in relation to FIG. 1, that the booster pump 7 which supplies the hydraulic action conduit 78 with hydraulic fluid 60 via the booster non-return valve 8 is none other than the greasing pump of the internal combustion engine 2 while the hydraulic fluid tank 11 consists of the oil sump of said engine 2.

[0126] In this context, advantageously, the force produced by the return spring of the receiver piston 79 is expected to be substantially greater than the force produced by the pressure generated by the lubricating pump of the internal combustion engine 2 on the receiver piston. 62.

[0127] It is also noted in Figures 1 and 11 that the injectable fluid supply pipe 66 is here arranged directly in the foundry of the cylinder head 3 while the injection cam 67 is driven by the camshaft of the cylinder head. internal combustion engine 2.

[0128] It will be assumed here that, as shown in FIG. 1, in FIGS. 3 to 6, and in FIG. 12, the cam profile 68 of the injection cam 67 is maintained in contact with the axial action face 75 of the transmitter piston 69 via a rocker arm 80, the latter being maintained in contact with the cam profile 68 by means of a pawl roller 86.

As illustrated in FIG. 1, in FIGS. 3 to 6, and in FIG. 12, it will also be assumed that the rocker arm 80 bears on the cam housing 81 by means of a movable support roller 84 which can roll or slide on a displacement track 85 provided in the cam housing 81, said roller 84 cooperating with a tilting track 87 provided on the back of the rocker arm 80.

[0130] In FIGS. 1, in FIGS. 3 to 6, and in FIG. 12, it can be noted that the displacement track 85 is advantageously perfectly perpendicular to the axis of the emitter piston 69. In addition, in FIGS. 1, 3, 5 , 6 and 12, it is noted that when the pawl roller 86 is in contact with the angular holding sector 16 and that the emitter piston 69 pushes on the rocker arm 80 via its axial action face 75 to press said rocker arm 80 on the track displacement 85 via the displaceable support roller 84, the tilting track 87 of said rocker arm 80 remains parallel to the displacement track 85 whatever the position of the displaceable support roller 84.

[0131] In this respect, it is noted that it is possible to provide a screw or cam adjustment device or any other adjustment means which makes it possible to adjust the perpendicularity of the displacement track 85 with respect to the axis of the emitter piston 69 and / or the distance of the displacement track 85 relative to the injection cam 67 along an axis parallel to that of the emitter piston 69. It is noted in FIG. 12 that said adjustment device can take the form of adjusting screw 21.

To counter any imprecision in the settings which have just been described, it is advantageously possible to provide that a little hydraulic fluid 60 escapes directly or in directly from the hydraulic action conduit 78 on each opening cycle of the injection valve 50. This can take place for example via the emitter piston 69, the sealing of which is imperfect, or via a nozzle of very small section placed at any point of the circuit which connects the emitting chamber 72 to the chamber receiver 71, said nozzle letting some hydraulic fluid 60 escape which returns to the hydraulic fluid tank 11.

Note, particularly in Figure 6, that the movable support roller 84 receives at each of its ends an orientation pinion 89, said pinions 89 being integral in rotation, while each said pinion 89 cooperates with a rack orientation 90 integral with the cam housing 81.

[0134] It is also noted that the movable support roller 84 receives a worm wheel 91 which cooperates with a worm 92 whose axial position is fixed relative to the cam housing 81, said screw 92 being driven in rotation by the injector lift actuator 83 which, according to this non-limiting example, consists of an electric step-by-step motor 93.

[0135] Note that advantageously, the diameter of the pitch circle of the pinions

orientation 89 and that of the worm wheel 91 are identical, which does not exclude the possibility that they are different.

[0136] Thus, when the electric stepper motor 93 rotates the worm 92, the

The movable support roller 84 moves relative to the travel track 85 with which it cooperates which results in the displacement of the position of the movable bottom point 82 relative to the cam housing 81.

[0137] This makes it possible to adjust the amount of injectable fluid 58 expelled from the nozzle.

tubular injection 54 to the valve ignition prechamber 1.

[0138] When the internal combustion engine 2 is running, the injection valve 50 is for example first kept closed by the receiving piston 62 due to the pressure which prevails in the tubular injection nozzle and, to a lesser extent. measurement, by the return spring of the receiving piston 79. This situation is illustrated in Figures 1 and 11, and results for example from any one of the angular positions of the injection cam 67 shown in Figures 1, 3, 5 or 6.

[0139] As shown in Figure 4, the internal combustion engine 2 continuing to rotate, the cam profile 68 pushes on the rocker arm 80. The latter rocks and moves the emitter piston 69 which, in return, forces the hydraulic fluid 60 to pass from the emitting chamber 72 to the receiving chamber 71. This has the effect of moving the receiving piston 62 and moving the valve sealing face 53 away from the injection valve seat 55, which has the effect of transfer injectable fluid 58 from the tubular injection nozzle 54 to the valve ignition prechamber 1.

[0140] FIG. 5 shows for its part that in order to adjust the lift height of the injection valve 50, the step-by-step electric motor 93 can bring the movable support roller 84 closer to or away from the emitter piston 69 by via the worm 92, this to modify the lever arm of the rocker arm 80 and therefore the displacement ratio between that of the emitter piston 69 and that of the receiver piston 62. [0141] In practice, the displacement ratio between the displacement of the emitter piston 69 and the effective lift of the injection valve 50 depends on the lever arm formed by the rocker arm 80, but also on the compressibility of the hydraulic fluid 60 contained in the emitting chamber 72, the receiving chamber 71 and the hydraulic action conduit 78.

[0142] The force that must be applied by the rocker arm 80 on the axial action face 75 of the emitter piston 69 depends in particular on the pressure of the injectable fluid 58 which prevails in the tubular injection nozzle 54 and on the ratio between the section exposed to the pressure of the injectable fluid 58 by the axial face on the injectable fluid side 63 and the section exposed to said pressure by the tulip 52.

[0143] To a lesser extent, said force is also dependent on the force produced by the return spring of the receiving piston 79. To this is added the inertia of the various moving parts and the energy losses they produce in rubbing against each other, and the pressure drops produced by the hydraulic fluid 60 by circulating in particular in the hydraulic action conduit 78.

[0144] However, at each operating point of the internal combustion engine 2 corresponds a position of the step-by-step electric motor 93 which makes it possible to introduce into the valve ignition prechamber 1 the quantity of pilot charge 9 most favorable to the thermodynamic efficiency of said motor 2. Finding the existing relation between the position of the electric stepper motor 93 and the quantity of pilot charge 9 can be carried out on the test bench for each operating point of the internal combustion engine 2 which avoids the development of a predictive numerical model, useless in this context.

[0145] Consequently, the position of the step-by-step electric motor 93 is provided to vary as a function of requirements, and in particular as a function of the speed, of the load, and of the dilution of the main load 30 of the combustion engine. internal 2. With regard to said dilution, it is noted that the more the main charge 30 is diluted with fresh air or with recirculated exhaust gases, the more it is resistant to ignition, and the more energy it contains. in the pilot charge 9 must be large relative to that contained in the main charge 30.

[0146] Furthermore, to introduce the same amount of pilot charge 9, the faster the internal combustion engine 2 turns and the higher the lift of the injection valve 50 must be. Indeed, for the same position of the displaceable support roller 84, the faster said motor 2 turns, the shorter the absolute duration of the lifting of the injection valve 50, in order to inject the same mass of injectable fluid 58 into the valve pre-ignition chamber 1. The reduction in the injection time must therefore be compensated for by an increase in the passage section left between the valve sealing face 53 and the injection valve seat 55 and therefore , by an increase in injection valve lift height 50.

It is also noted that the internal combustion engine 2 running quickly, the effects of the compressibility of the hydraulic fluid 60 are more marked due to

the increased acceleration of the parts to be moved and the increase in peak pressure reached by said fluid 60 resulting therefrom. This effect is also to be compensated for by an appropriate position of the support roller 84 movable via the electric stepping motor 93.

[0148] The mapping of the ideal position of the step-by-step electric motor 93 taking into account the operating conditions of the internal combustion engine 2 is stored in the memory of a computer 48, corrected or not by algorithms taking into account contextual operating parameters such as temperature or

aging.

[0149] It will be noted that when the internal combustion engine 2 starts at very low temperature - for example minus thirty degrees Celsius - the pressure of the injectable fluid 58 prevailing in the injectable fluid supply duct 66 and in the nozzle of the injectable fluid. tubular injection 54 must be drastically reduced, for example to five bars instead of fifty bars.

[0150] This lower pressure makes it possible not to condense the gasoline constituting the

air-fuel mixture AF, and to keep its nominal richness in said mixture. It follows from this that during the temperature rise phase of the internal combustion engine 2, the maximum load of the latter is limited to approximately ten bars of effective mean pressure, which immediately makes any motor vehicle equipped with it usable.

[0151] A few seconds later, the rapid rise in temperature of the pressurizing means 10, of the injectable fluid supply duct 66, and of the tubular injection nozzle 54 makes it possible to resume normal operation with a pressure of injectable fluid 58 in the tubular injection nozzle 54 reaching about fifty bars.

[0152] The example of operation which has just been given of the injection system hy

hydraulic cam 100 according to the invention is in no way limiting. Indeed, said system is capable of allowing the direct or indirect injection of natural gas, heavy fuel oil, diesel or gasoline into any internal combustion engine 2, whatever the principle.

[0153] In general, the following 100 cam hydraulic injection system

the invention is capable of allowing the injection of any gas and / or any liquid into any machine requiring such an injection, whether or not controlled by an injector lift actuator 83.

[0154] Also, the possibilities of the following 100 cam hydraulic injection system

the invention is not limited to the applications which have just been described and it must moreover, it should be understood that the above description has been given only by way of example and that it in no way limits the field of the said invention, from which one would not depart by replacing the details of execution described by any other equivalent.

Claims

[Claim 1] Hydraulic cam injection system (100), characterized in that it comprises:

• At least one injection valve (50) which comprises a valve stem (51) and which ends in a tulip (52), the latter exposing a valve sealing face (53), said valve (50) being wholly or partly housed in a tubular injection nozzle (54) terminated by an injection valve seat (55) on which the valve sealing surface (53) can sealingly rest while a space is left between the valve stem (51) and the internal surface of the tubular injection nozzle (54) to circulate an injectable fluid (58) pressurized by pressurizing means (10);

• At least one nozzle inlet port (59) provided in the tubular injection nozzle (54) and through which the injectable fluid (58) is introduced inside said nozzle (54);

• At least one slave cylinder (61) which is directly or in directly secured to the end of the tubular injection nozzle (54);

• At least one receiving piston (62) integral with the valve stem (51) and housed in the receiving cylinder (61), said piston (62) being able to move in longitudinal translation in said cylinder (61) and having an axial face injectable fluid side (63) which communicates with the interior volume of the tubular injection nozzle (54), and an axial face on the hydraulic fluid side (64) which forms, with the receiving cylinder (61) a receiving chamber (71) of variable volume filled with hydraulic fluid (60);

• At least one hydraulic fluid supply device (65) connected to the receiving chamber (71) and which makes it possible to actuate the receiving piston (62) via the hydraulic fluid (60) via a hydraulic conduit action (78).

[Claim 2] A hydraulic cam injection system according to claim 1, ca- characterized in that a receiving piston return spring (79) tends to bring the receiving piston (62) closer to a receiving cylinder head (74).

[Claim 3] A hydraulic cam injection system according to claim 1, characterized in that permeable guide means (56) are directly or indirectly integral with the injection valve (50) and / or the nozzle d tubular injection (54), said means (56) keeping the injection valve (50) approximately centered in the tubular injection nozzle (54).

[Claim 4] A hydraulic cam injection system according to claim 1, characterized in that the hydraulic fluid supply device (65) consists of an injection cam (67) which has at least one profile of cam (68) maintained directly or indirectly in contact with an axial action face (75) presented by a master piston (69) housed in a master cylinder (70), said piston (69) having - opposite to the axial action face (75) - an axial hydraulic fluid emission face (76) which forms an emitter chamber (72) with the master cylinder (70) while the cam profile (68) can move the sender piston (69) in longitudinal translation in the emitter cylinder (70) when the injection cam (67) is rotated by a driving source (73).

[Claim 5] A hydraulic cam injection system according to claim 4, characterized in that the hydraulic action conduit (78) connects the emitting chamber (72) to the receiving chamber (71), said conduit (78), the emitting chamber (72) and the receiving chamber (71) being filled with hydraulic fluid (60).

[Claim 6] A hydraulic cam injection system according to claim 4, characterized in that the cam profile (68) comprises at least one angular lift sector (15) which moves the emitter piston (69) when said sector ( 15) is in contact with the axial action face (75) and that the injection cam (67) is rotating, and at least one angular retaining sector (16) which is circular and centered on the axis of rotation of said injection cam (67) which immobilizes the emitter piston (69) when said sector (16) is in contact with the axial action face (75) and this despite the injection cam (67) being in rotation.

[Claim 7] Hydraulic cam injection system according to Claim 4, characterized in that the cam profile (68) is maintained in contact with the axial action face (75) by means of a rocker arm ( 80) which bears directly or indirectly on a cam housing (81) in which the injection cam (67) rotates.

[Claim 8] A hydraulic cam injection system according to claim 7, characterized in that the rocker arm (80) bears on the cam housing (81) via a movable tipping point (82) of which the position between the cam profile (68) and the axial action face (75) can be changed by an injector lift actuator (83).

[Claim 9] A hydraulic cam injection system according to claim 8, characterized in that the movable tipping point (82) consists of a movable backing roller (84) which can roll or slide on a track. displacement (85) provided in the cam housing (81), said roller (84) cooperating with a tilting track (87) provided on the back of the rocker arm (80).

[Claim 10] A hydraulic cam injection system according to claim 9, characterized in that the movable support roller (84) receives at each of its ends an orientation pinion (89), said pinions (89) being integral in rotation, while each said pinion (89) cooperates with an orientation rack (90) integral with the cam housing (81).

[Claim 11] A hydraulic cam injection system according to claim 10, characterized in that the movable support roller (84) receives a worm wheel (91) which cooperates with a worm (92) of which the axial position is fixed relative to the cam housing (81), said screw (92) being able to be driven in rotation by G injector lift actuator (83).

[Claim 12] A hydraulic cam injection system according to claim 10, characterized in that the movable backing roller (84) receives a thread in which the injector lift actuator (83) can rotate a screw of movement (17) which is integral in position with the cam housing (81) but free to rotate about its longitudinal axis.

[Claim 13] A hydraulic cam injection system according to claim 4, characterized in that an injection cam phase shifter (96) is interposed between the injection cam (67) and the driving source (73).

[Claim 14] A hydraulic cam injection system according to claim 1, characterized in that the end of the tubular injection nozzle (54) which terminates with the injection valve seat (55) is capped with 'a diffuser with holes (94).

[Claim 15] A hydraulic cam injection system according to claim 14, characterized in that at least part of the inner wall of the hole diffuser (94) is cylindrical and leaves a small clearance between itself and the outer peripheral surface of the tulip (52) such that said diffuser (94) forms the permeable guide means (56).

[Claim 16] A hydraulic cam injection system according to claim 1, characterized in that a booster pump (7) tends to introduce hydraulic fluid (60) into the hydraulic action line (78) via a valve booster check valve (8), said hydraulic fluid (60) coming from a hydraulic fluid tank (11).

[Claim 17] A hydraulic cam injection system according to claim 1, characterized in that at least one drainage orifice (97) connected to a drainage duct (99) opens into the receiving cylinder (61), the face axial face on the injectable fluid side (63) and the axial face on the hydraulic fluid side (64) always remaining axially positioned on either side of said orifice (97) whatever the position of the receiving piston (62).

[Claim 18] A hydraulic cam injection system according to claim 17, characterized in that the receiving piston (62) has a drainage groove (98) which communicates with the drainage port (97).

[Claim 19] A hydraulic cam injection system according to claim 18, characterized in that the receiving piston (62) consists of a first body which receives the axial face on the injectable fluid side (63) and which is integral with the valve stem (51), and a second body, whether or not integral with said first body and which receives the axial face on the hydraulic fluid side (64), an external shoulder (20) arranged on one or the other or both two said bodies forming the drainage groove (98).

[Claim 20] A hydraulic cam injection system according to claim 8, characterized in that the maximum range of displacement of the movable bottom point (82) between the cam profile (68) and the axial action face ( 75) is determined by at least one end stop (19).

[Claim 21] A hydraulic cam injection system according to claim 9, characterized in that the movement track (85) is made integral with the cam housing (81) by means of at least one ball joint

track orientation (18).

[Claim 22] A hydraulic cam injection system according to Claim 1, characterized in that the receiving piston (62) consists of at least a first body which receives the axial face on the injectable fluid side (63) and which is integral of the valve stem (51), and at least one second body, whether or not integral with said first body and which receives the axial face on the hydraulic fluid side (64). [Claim 23] A hydraulic cam injection system according to claim 22, characterized in that the receiving piston (62) comprises an outer shoulder (20) provided on one, the other or both bodies, said shoulder ( 20) forming a drainage groove (98) which communicates with at least one drainage opening (97) which is provided in the receiving cylinder (61) and which is connected to a drainage duct (99).