EP2166198B1 - Method to control intake and exhaust valves of an internal combustion engine, from which at least one cylinder can be shut down and engine controlled by that method - Google Patents

Description

The present invention relates to an internal combustion engine of the degraded operating type of at least one cylinder and to the use of such an engine for operation at low or medium loads.

It is intended more particularly but not exclusively direct or indirect injection engines, of the Gasoline type, but does not exclude in any way diesel direct injection engines.

Usually, an engine works with all of its cylinders. However, when this engine runs at low or medium loads, the engine performance is degraded by the increase in the contribution of friction and winnowing in the case of gasoline type engines.

It has already been proposed to operate only part of the cylinders of this engine and to inactivate the remaining part, which increases the load of the cylinders remaining active.
To do this, it is planned to cut the fuel injection only in the cylinders that you want to disable. This makes it possible to promote the reduction of fuel consumption by injecting the necessary fuel only in the cylinders necessary for the production of energy for operation of the engine with low or partial loads.

Thus, for example in the case of a four-cylinder engine, it can be expected to render inactive two cylinders and thus obtain a combustion in the active cylinders for each crankshaft revolution.

Although this type of operation of the engine is satisfactory, it nevertheless entails significant disadvantages.

Indeed, as the laws of lift of the exhaust and intake valves remain unchanged, the different phases of admission and exhaust or inactive cylinders will cause malfunctions.
Thus, when cutting the fuel supply of the cylinder to be inactive, no fuel mixture is produced in the combustion chamber and only a volume of air is present after the intake phase. This volume will then be compressed during the phase of this cylinder which corresponds to its compression phase. During the phase following this compression phase and in the absence of combustion, the piston will not be subjected to a force resulting from the expansion of the flue gas but only relaxes a volume of compressed air. This generates a cooling of the air contained in the cylinder and this drop in temperature will be transmitted to the wall of the cylinder. This cooling is also transmitted to the entire exhaust line during the exhaust phase of the inactive cylinder with a movement of the piston from the bottom of the cylinder to the top of the cylinder. During this movement, the cold expanded air is pushed by the piston towards the exhaust valve and runs through the entire exhaust line causing not only its cooling but also the dilution of the exhaust gas. This can pose significant problems in the various means of depollution that includes this line and in particular at the level of the catalysts.

In addition, during the reactivation of these initially deactivated cylinders, the latter are cold and thus cause difficulties in achieving the combustion of the fuel mixture.

He is known, in particular by the documents US 4,768,475 , US 2006/2725989 or JP 61 084106 an internal combustion engine comprising at least one cylinder having intake means with an intake valve, exhaust means with an exhaust valve, and valve opening / closing control means, said means control system comprising control means and means for transmitting movement and effort between said control means and the valve to be controlled, said movement and effort transmission means comprising a rocker arm with at least two disengageable rockers a sole controlling the movement of said valve and means for alternating coupling between the sole and one or other of the rockers

In these different types of internal combustion engines, the means of alternating coupling between the sole and one or the other of the rockers are of a complicated design, which strike the cost of producing such means. In addition, the latter have many movable parts relative to each other that are difficult to control in their movement and can hang causing a malfunction that can cause deterioration of the engine.

The present invention aims to overcome the aforementioned drawbacks by means of a simple engine design and economic to further reduce fuel consumption while maintaining the temperature of the cylinders and using simple coupling means of simple elaboration and inexpensive.

For this purpose, the present invention relates to an internal combustion engine comprising at least one cylinder comprising intake means with an intake valve, exhaust means with a valve exhaust, and valve opening / closing control means, said control means comprising control means and means for transmitting movement and effort between said control means and the valve to be controlled, said means for transmission of movement and effort comprising a rocker arm with at least two disengageable rockers a sole controlling the movement of said valve and means for alternating coupling between the sole and one or the other of the rockers, characterized in that that the coupling means comprise a jack with a piston provided with two rods cooperating to lock with said rockers.

The control means may comprise a camshaft carrying cams cooperating with each rocker.

One of the cams may comprise a cam profile cooperating with one of the rockers which is different from the cam profile of the other of the cams cooperating with the other rockers.

The piston rod can secure the rocker with the sole by cooperation with a hole carried by said rocker.

Particularly advantageously, the jack can be carried by the sole.

The soleplate may preferably comprise a discharge of the fluid out of the jack.

In the case where the rocker arm pivots about a rocker shaft, the rocker shaft may be a rotary shaft having a fluid supply channel said cylinder and a connecting channel in connection with a fluid discharge passage carried by the sole.

The engine may comprise means for transmitting motion between the camshaft and the crankshaft of the engine with a transmission ratio for rotating said shaft at one-third of the rotational speed of said crankshaft and means for transmitting motion between the crankshaft. camshaft and rocker shaft with a gear ratio for rotating said rocker arm shaft to half the rotational speed of the camshaft.

The present invention also relates to the use of such a motor, for operation, according to low or medium engine loads, with a cycle comprising at least two additional phases to the conventional phases of admission, compression, combustion of a fuel mixture and exhaust gases.

These additional phases may be, following the conventional exhaust phase, a flue gas expansion phase followed by a recompression phase of the flared gases burned.

• la figure 1 qui montre un moteur à combustion interne selon l'invention ;
• les figures 2 et 3 qui sont des graphiques montrant les différentes lois de levée des soupapes (L) en fonction de l'angle de vilebrequin (°V) pour le moteur selon l'invention ;
• la figure 4 qui illustre un mécanisme de contrôle de soupapes pour le moteur selon l'invention ;
• la figure 5 qui montre le mécanisme de la figure 4 dans une autre position selon l'invention et
• la figure 6 qui est une variante du mécanisme de contrôle de soupapes de la figure 4.

The other features and advantages of the invention will appear on reading the description which follows, given by way of illustration and not limitation, and to which are appended:

• the figure 1 which shows an internal combustion engine according to the invention;
• the Figures 2 and 3 which are graphs showing the different valve lift laws (L) as a function of the crankshaft angle (° V) for the engine according to the invention;
• the figure 4 which illustrates a valve control mechanism for the engine according to the invention;
• the figure 5 which shows the mechanism of the figure 4 in another position according to the invention and
• the figure 6 which is a variant of the valve control mechanism of the figure 4 .

On the figure 1 , the internal combustion engine, of the direct injection type of fuel, in particular a gasoline type engine, comprises at least one cylinder, here four cylinders referenced 10, 12, 14, 16 of which at least one of the cylinders can have a degraded operating mode for low or medium loads.

Each cylinder contains a piston (not shown) sliding in a reciprocating rectilinear motion being connected to a crankshaft (symbolized by the center line 18). The piston thus defines with the cylinder a combustion chamber where the combustion of a fuel mixture can be achieved when the conditions of such a combustion are combined.
This piston oscillates between a high position, called top dead center (TDC), for which the combustion chamber occupies a reduced volume and a low position, called bottom dead center (BDC), where the volume of the combustion chamber is the highest. important. The stroke of this piston between these two dead spots corresponds to a phase of operation.

As illustrated in this figure, each cylinder comprises intake means 20 with at least one intake valve 22 controlling an intake manifold 24. The intake manifolds are connected to an intake manifold 26 which is connected to a fluid inlet 28, such as outside air.
The outside air can be either air at ambient pressure or supercharged air, which is compressed by a turbocharger for example, before its introduction into the cylinders. This air at ambient pressure or supercharged can also be mixed with exhaust gas in the case of engine operation with exhaust gas recirculation EGR (EGR for Exhaust Gas Recirculation).

Each cylinder also comprises exhaust means 30 with at least one exhaust valve 32 controlling an exhaust manifold 34 connected to an exhaust manifold 36 connected to an exhaust line 38 for venting into the atmosphere the flue gases from the combustion of the fuel mixture in the cylinders.

Of course, this line may include means for the depollution of these exhaust gases, such as catalysts, before their release into the atmosphere.

As is known per se, each cylinder comprises fuel injection means (not shown) for producing a fuel mixture in the cylinder. The ignition of this fuel mixture can be achieved either by ignition means, such as a spark plug (also not shown), or by auto-ignition.

These intake valves 22 and the exhaust valves 32 are controlled in opening and closing by control means 40 respectively 42, the following description will be more detailed.

These control means are configured in such a way that, in combination with the fuel injection means and possibly the ignition means in the case of a spark ignition engine, the cylinders 10 to 16 can respond to the two illustrated operating configurations. to the Figures 2 and 3 .

In the case of conventional operation illustrated in figure 2 , especially for the high load levels, the cylinders 10 to 16 operate in a conventional cycle (C) of four phases during two crankshaft revolutions (T). This cycle comprises, during one turn, an intake phase (A) between the PMH and the PMB of the piston with a sequence of opening and closing of the intake valve 22, and a phase of compression (CP) between the PMB and the PMH of this piston, then, in a following turn, a combustion phase (CB) of the fuel mixture present in the cylinder from the PMH of the piston to its PMB, and an exhaust phase (E) burnt gases ranging from PMB to PMH with a sequence of opening / closing of the exhaust valve 32. These four conventional phases are repeated in two crankshaft turns, or 720 ° crank angle. Thus each cycle (C) begins with an admission phase (A) and ends with an escape phase (E).

In the case of the configuration of the figure 3 illustrating the operation at low or medium loads, at least one cylinder, here the cylinder 10, operates in a degraded manner with a cycle (C ') of six phases for three turns (T) of crankshaft. These phases are divided into four previously mentioned phases (intake, compression, combustion and exhaust phases according to two laps) followed, for an additional revolution, by two additional phases: a relaxation phase (D) during which the Residual flue gases contained in the cylinder are expanded between the PMH and the PMB of the piston and a recompression (RC) phase of the burnt gases expanded with a piston stroke between the PMB to the PMH. These last two phases are performed by maintaining in the closed position the intake and exhaust valves. This operating cycle (C ') therefore starts with an admission phase (A) and ends with a recompression phase (RC).

Thus, in conventional operation, the engine operates with all the cylinders that follow the four-phase cycle with more precisely one combustion phase every four phases, ie every two turns.
In the case of operation at low or medium loads, it is expected to change the engine with all or part of the cylinders operating in degraded mode with a single combustion phase (CB) in a six-phase cycle on three crankshaft revolutions. In the case where only part of the cylinders operates in degraded mode, the remaining part of the cylinders operates in conventional mode.
This allows, unlike the engines of the prior art with deactivation of cylinders, to maintain the temperature of the various elements of the cylinder (cylinder wall, piston, ...) and not to disturb the exhaust line while reducing significantly the fuel consumption.

To do this and referring to the figure 4 , the control means 40, the intake valve and the control means 42 of the exhaust valve comprise control means and means for transmitting movement and effort between these control means and the valve to control, regulate. These control means make it possible to operate the cylinder in question, either in degraded mode or in conventional mode.

In the remainder of the description, mention will be made only of the control means 40 applied to the intake valve 22, but this description also applies to the control means 42 of the exhaust valve 32.

In the example of the figure 4 the control means comprises a rotary camshaft 44. This camshaft comprises a shaft 46 fixedly holding a first cam 48 and a second cam 50, spaced from each other, with different cam profiles 52, 54 and controlling the same valve.

The terms "first" or "first" and "second" or "second" used in the description do not prevail in their use but are used only to differentiate, from one another, two substantially identical elements.

The means of transmission of movement and effort 56 between the control means 44 and the intake valve 22, symbolized by the circle dashed lines, include a rocker 58 pivoting about a rocker shaft 60 which is itself rotatable about its longitudinal axis. This rocker shaft is placed between the inlet valve 22 and the camshaft 44 being substantially parallel to this camshaft.

The rocker arm includes a flat sole plate 62 of elongated profile having, in the vicinity of its end 66 closest to the camshaft, a bore 64 cooperating in sliding rotation with the rocker arm shaft and a contact zone 68 with the tail of the valve 22 near its other end 70.

On both sides of this sole and in contact with it, are placed axially a first rocker 72 and a second rocker 74, in the form of a bar, which are also pivotally mounted on the rocker arm shaft 60 by means of a bore 76, 78 carried by the body 80, 82 of these rockers.
The longitudinal dimensions of these rockers are such that one 84 of the ends of the first rocker 72 bears on the first cam 48 and one 86 of the ends of the second rocker 74 bears on the second cam 50.
The other 88, 90 of these rocker ends comprise means of cooperation, here a first hole 92 and a second hole 94 substantially parallel to the rocker shaft, with coupling means 96 carried by the sole 62. These means are provided for coupling (or uncoupling) alternately, the first rocker 72 with the sole 62 or the second rocker 74 with the same sole.

The coupling means comprise a jack 97, of hydraulic single-acting type, carried by the sole plate 62.
This jack comprises a cavity 98, for example cylindrical with two vertical flanks 100, 102, placed in the body of the sole. This cavity continues, in the direction of the rockers and from the flanks, by holes 104, 106, preferably cylindrical and coaxial with the cavity, which are respectively facing holes 92, 94 being of the same radial dimension. A translational piston 108, preferably stepped, is housed in this cavity with a piston body 110 for delimiting two sealed chambers 112, 114, one of which 112 comprises an elastic means, such as a return spring 116. This body piston piston, on both sides, a first rod 118 and a second rod 120 which cooperate with the holes 104, 106 and then with one or other of the holes 92, 94 of the rockers 72, 74.

A circulation passage 122 of a pressurized control fluid, such as oil, is located between the cavity 98 and the bore 64 of the soleplate with an outlet of this passage closest to the vertical wall 102 of the chamber 114 which has no spring. This passage also comprises a fluid circulation bypass 124 placing this passage in communication with the bore 64. A fluid evacuation passage 126 is also provided in the sole remote from the feed passage. This evacuation passage is advantageously placed between the bore 64 and the edge of the end 66 of the sole.

The rocker shaft 60 internally comprises an axial channel for supplying pressurized fluid 128 with a radial inflow of fluid 130 in communication, from the periphery of this shaft, with an intake manifold 131 of fluid under pressure F This channel also comprises a fluid outlet 132 opening radially on the periphery of this shaft while being in concordance with the communication passage 122.
The inlet 130 and the outlet 132 of the channel 128 as well as the housing 131 are dimensioned in such a way that they allow the supply of the chamber 114 during the entire rotation of a half turn of the rocker arm shaft. 60 from the figure 4 .
This shaft also comprises a connecting channel 134 substantially radial and remote from the supply channel. This connecting channel comprises a radial bowl 136 continuing with a connecting passage 138 whose section cross section is substantially equal to the cross section of the evacuation passage 126.
The configuration of this channel is such that the cuvette may be in communication with the bypass 124 and the connecting passage may be in communication with the evacuation passage 126 for another half turn of the rocker shaft, as will be made explicit. in the following description.

Of course, there is provided all sealing means between the various moving and fixed parts to prevent leakage of control fluid.

The rocker shaft and the camshaft are kinematically connected in rotation by any transmission means, such as a gear train 140, so that the rocker arm shaft rotates at half the speed of rotation. the camshaft.
The rotational movement of this camshaft is conventionally controlled by the crankshaft 18 through a timing belt (or a chain, or a gear train) so that the rotational speed of this camshaft camshaft is one third of that of the crankshaft.

So concretely, for a rotation of three turns of the crankshaft, the camshaft rotates one turn while the rocker arm shaft turns a half turn.

In conventional operation of the engine cylinders, at full loads in particular, the control means are initially in the configuration of the engine. figure 4 .
The pressurized fluid F is introduced by the housing 131 into the inlet 130. This fluid flows in the channel 128 to reach the outlet 132 and is then passed through the communication passage 122 into the chamber 114. This pressurized fluid fills the 114 chamber by pushing the piston 108 to the right (considering this figure) while compressing the spring 116.

Arrived at this position (illustrated in dotted lines in the figure), the first rod 118 of this piston cooperates with the hole 92 of the first rocker 72 and the second rod 120 has released the hole 94 of the second rocker 74.

As a result, when the camshaft is rotated one full revolution corresponding to the rotation of a half turn of the rocker shaft, the second cam 50, which is in contact with the end 86 of the rocker shaft, second rocker 74, causes the pivoting of this rocker around the rocker shaft 60. As this rocker is no longer mechanically linked to the sole 62 because of its uncoupling with the sole 62, it can not act on the tail of the valve through the sole 62.
In contrast, the rotation of the first cam 48 will cause a control of the intake valve 22. Indeed, by the actuation of the coupling between the sole 62 and the rocker 72, the rotation of this cam makes it possible to generate the tilting of the sole assembly 62 - first rocker 72 around the rocker arm shaft by the contact of the end 84 of this rocker with the profile 52 of the first cam 48. By this rocking, the zone contact 68 of the sole causes the translational movement of the valve by opening / closing the orifice of the tubing it controls.

By referring to the figure 2 , the rotation of the camshaft on one turn occurs during a rotation of three turns of the crankshaft, so from 0 ° V to 1080 °.
During the rotation of one revolution of this camshaft, the rocker shaft rotates a half turn with a position of the cylinder rods 118, 120, as shown in dotted lines on the figure 4 .
As a result, during the operating cycle (C), the inlet valve follows an opening / closing sequence between 0 ° V and 180 ° V and then, during the next cycle (C), an opening / closing sequence. closing between 720 ° V and 900 ° V.
For this, the cam 48 has a suitable profile for performing, during a camshaft revolution, this sequence of sequences.

When the rocker shaft 60 has completed its half turn under the impulse of the camshaft, it is in the position illustrated in FIG. figure 5 .
In this position, not only is the fluid no longer introduced into the supply channel 128 but also this channel is no longer in relation with the fluid communication passage 122.
The chamber 114 is therefore no longer under pressure and the bypass 124 is in communication, through the connecting channel 134, with the evacuation passage 126.
Under the effect of the return spring 116 present in the chamber 112, the piston 108 is pushed to the left (considering this figure) and the fluid contained in the chamber 114 is expelled from it.
This fluid then travels a portion of the communication passage 122 and the bypass 124 and ends in the bowl 136 of the connecting channel 134. From this bowl, the fluid passes through the connecting passage 138 and the evacuation passage 126 to to reach all means of receiving this fluid such as a tank or tank.
Finally, the piston 108 and rods 118, 120 are in the configuration in which the first rocker 72 is uncoupled from the sole 62 while the rocker 74 is coupled to this sole.
During crankshaft rotations on three additional turns, ie from 1080 ° V to 2160 ° V, the camshaft rotates one revolution and the rocker shaft rotates for half a turn.
Under the impulse of the second cam 50, which has an adapted profile 54, the inlet valve follows an opening / closing sequence between 1440 ° V and 1620 ° V to start the next operating cycle (C).

When the rocker shaft 60 has completed its half turn under the impulse of the camshaft, it is in the position illustrated in FIG. figure 4 . In addition, the piston 118 is found, under the impulse of the spring 116, in the initial position as shown in this figure.

During degraded operation of at least one cylinder 10, such as for the low or medium loads of the engine, it is intended to operate this cylinder with a cycle (C ') which allows to have a combustion phase (CB) every six times, as described in relation to the figure 3 .
By way of non-limiting example, during the degraded operation of this cylinder 10, the other cylinders 12 to 16 operate in conventional mode.

For this, from the configuration of the figure 4 , the fluid supply channel 128 is not supplied with pressurized fluid during the entire rotation on one turn of the rocker shaft 60. The first rocker 72 therefore remains uncoupled from the sole 62 during all this rotation and the second rocker 74 is constantly coupled with this sole.

Considering the profile 54 of the second cam 50, the inlet valve 22 follows an opening / closing sequence according to an operating cycle (C ') every three turns, such that between 360 ° V and 540 ° V then according to the following cycle (C ') between 1440 ° V and 1620 ° V.
Thus, this configuration makes it possible, as already mentioned, to obtain a single combustion phase (CB) according to a six-phase operating cycle (C ').

As the exhaust valve 32 is subjected to control means identical to those of the intake valve, this exhaust valve also follows opening / closing sequences with an angular offset of 540 ° and this as well for the conventional operation of the engine cylinder only for degraded operation at low or medium loads.

Of course, the arrival of fluid in the channel 128 is controlled by a hydraulic circuit (not shown) controlled by a control unit (also not shown) that usually includes any engine. This unit contains maps or data tables that allow you to operate all or part of the cylinders, depending on the conditions of evolution of the engine.

Likewise, this unit makes it possible to control the fuel injection parameters in the cylinder as well as the ignition parameters of the fuel mixture present in this cylinder.

The variant of the figure 6 differs from the example of the figure 4 by the arrangement for evacuating the fluid expelled from the chamber 114 from the coupling means 96.
In this variant, the bypass 124, the connecting channel 134 (connecting bowl 136, connecting passage 138) and the evacuation passage 126 have been replaced by a calibrated evacuation channel 142 contained in the sole 62. This channel , which has a calibrated cross section, originates at the chamber 114 to end on an edge of the end 70 of the sole.
For the conventional operation of the cylinder, the fluid is introduced under pressure into the chamber 114 by the supply channel 128 and the communication passage 122, as already explained in connection with the figure 4 . This fluid exerts pressure on the piston by moving it to the right of the figure. Given the calibration of the evacuation channel 142, which the skilled person will have previously determined by any means, the fluid introduced into the chamber 114 is brought out through this channel but with a flow rate less than that from the passage 122. Because of the differential pressure between the introduction of the fluid and its evacuation, the pressure in the chamber is sufficient to maintain the piston in its position illustrated in FIG. figure 5 .

When the fluid inlet is stopped, no pressure reigns in the chamber 114. Under the effect of the spring 116, the fluid contained in this chamber is discharged through the channel 142 and the piston arrives in the position shown in FIG. figure 6 .

The present invention is not limited to the embodiment described but encompasses all equivalents or variants.

Claims (10)

1. An internal-combustion engine comprising at least one cylinder (10, 12, 14, 16) including intake means with an intake valve (22), exhaust means with an exhaust valve (32) and control means (40, 42) for controlling opening/closing of the valves, said control means comprising drive means (44) and means (56) intended for motion and load transmission between said control means and the valve to be controlled, said motion and load transmission means (56) comprising a rocker arm (58) with at least two rockers (72, 74) disengageable from a pad (62) controlling the motion of said valve and means (96) for alternating coupling between pad (62) and one or the other of rockers (72, 74), characterized in that the coupling means comprise a jack (97) with a piston (108) provided with two rods (118, 120) cooperating through locking with said rockers.
2. An internal-combustion engine as claimed in claim 1, characterized in that the control means comprise a camshaft (44) carrying cams (48, 50) cooperating with each rocker.
3. An internal-combustion engine as claimed in claim 2, characterized in that one (48) of the cams comprises a cam profile (52) cooperating with one (72) of the rockers that is different from the cam profile (54) of the other cam (50) cooperating with the other rocker (74).
4. An internal-combustion engine as claimed in claim 1, characterized in that piston rod (118, 120) of jack (97) secures rocker (72, 74) to pad (62) through cooperation with a hole (92, 94) provided in said rocker.
5. An internal-combustion engine as claimed in claim 1, characterized in that jack (97) is carried by pad (62).
6. An internal-combustion engine as claimed in claim 5, characterized in that the pad comprises an outlet (126, 142) for discharging the fluid out of jack (97).
7. An internal-combustion engine as claimed in any one of the previous claims, wherein the rocker arm swivels round a rocker arm shaft (60), characterized in that the rocker arm shaft is a rotary shaft and in that it comprises a delivery channel (128) for carrying the fluid to said jack and a linking channel (134) connected to a fluid discharge passage (126) carried by the pad.
8. An internal-combustion engine as claimed in claim 7, characterized in that it comprises means intended for motion transmission between camshaft (44) and the engine crankshaft with a transmission ratio allowing said shaft to be rotated at one third of the rotating speed of said crankshaft and means (140) intended for motion transmission between camshaft (44) and rocker arm shaft (60) with a transmission ratio allowing said rocker arm shaft to be rotated at half the rotating speed of the camshaft.
9. Use of an internal-combustion engine as claimed in any one of the previous claims for operation at low or medium engine loads, with a cycle (C') comprising at least two additional phases (D, RC) to the conventional phases of intake (A), compression (CP), combustion (CB) of a fuel mixture and exhaust (E) of the burnt gases.
10. Use of an engine as claimed in claim 9 with, after the conventional exhaust phase (E), a burnt gas expansion phase (D) followed by an expanded burnt gas recompression phase (RC).

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