WO2007085754A2

WO2007085754A2 - Device for deactivating cylinders of an internal combustion engine

Info

Publication number: WO2007085754A2
Application number: PCT/FR2007/050644
Authority: WO
Inventors: Saïd IZELFANANE
Original assignee: Peugeot Citroën Automobiles SA
Priority date: 2006-01-25
Filing date: 2007-01-12
Publication date: 2007-08-02
Also published as: WO2007085754A3; FR2896540A1; EP1984603A2; FR2896540B1

Abstract

The subject of the present invention is a device for deactivating at least one cylinder (17, 18) of an internal combustion engine of the multi-cylinder type, comprising means (20, 21, 22, 23) for disabling the inlet or exhaust valves of the said cylinder which means can be actuated by a pressurized fluid, a pressurized-fluid supply circuit (15), a controlled electrically operated valve (14) and a secondary circuit (5) connecting the said electrically-operated valve (14) to the said disabling means (20, 21, 22, 23), auxiliary supply means (30) intended to supply the secondary circuit (5) with fluid outside of periods during which said disabling means (20, 21, 22, 23) are being actuated, and characterized in that auxiliary supply means (30) comprise a valve (34) intended to keep the pressure in the auxiliary supply means (30) below a threshold pressure (Pseuil).

Description

DEVICE FOR DISENGAGING CYLINDERS OF A MOTOR

INTERNAL COMBUSTION

The present invention claims the priority of the French application 0650254 filed on January 25, 2006, the entire contents of which are incorporated herein by reference.

The present invention relates to a device for deactivating cylinders of an internal combustion engine.

Internal combustion engines and in particular engines fitted to motor vehicles or road vehicles are solicited most of the time at a fraction of their nominal power. In these phases of operation that do not claim to deliver a significant torque, the engines suffer pumping losses that affect their performance and which are at the origin of excessive fuel consumption. These pumping losses correspond to the work that must be provided to suck the air / fuel mixture that is in the intake manifold at a relatively low pressure and introduce it into the combustion chamber during the intake phase.

To reduce these pumping losses, it is known to inactivate a number of cylinders. These deactivated cylinders then see their intake and exhaust valves closed and they are no longer traversed by any flow of gas mixture. These deactivated cylinders generate almost no more pumping losses because they operate as pneumatic springs, their piston alternating the compression and decompression phases of the gaseous mixture trapped in these cylinders. As for the cylinders remaining active, they must produce a larger torque and therefore require a higher flow of intake air into the manifold which increases the pressure in the distributor and thus reduces the losses by pumping the engine. The deactivation of the cylinders is conventionally performed by an appropriate mechanism acting on the distribution of the cylinders according to the operating conditions of the engine. In the case of a distribution by camshafts and pawls, it is thus known to associate with the hydraulic stops catch-up game on which latches, such a mechanism for disengaging the stops when you want to disable the cylinders. Disengagement of the stops is conventionally performed hydraulically by raising, in a ramp supplying the disengagement mechanism, the pressure above a calibrated threshold pressure. Patent FR2837871 illustrates an example of such a mechanism.

However, after several hours of non-operation of the engine, the ramp feeding such a mechanism is empty due to leakage generated at the disengaging mechanism. This is why, during the first cylinder deactivation action, it is first necessary to fill the feed ramp of the disengaging mechanism before being able to raise the pressure above the calibrated threshold pressure. As a result, the first deactivation action of the rolls has a drawback materialized by a very long response time.

The document FR0452786 proposes to eliminate this disadvantage by maintaining a minimum pressure in the feed ramp of the disengagement mechanism by means of an auxiliary supply calibrated however so as not to exceed the threshold pressure which activates the disengaging mechanism. This solution, although very relevant, however, has an important constraint: the calibration of the auxiliary power supply. The latter must indeed make it possible to compensate for leaks that affect the feed ramp of the release mechanism while maintaining the pressure in the ramp below a certain threshold. However, generally the auxiliary supply is itself supplied with fluid at very fluctuating pressures, since it derives from a main power supply for hydraulic actuators. As a result, the pressure amplitude at which the auxiliary supply is subjected is too high and makes it difficult to calibrate the auxiliary power supply in accordance with the requirements described above. Therefore, the present invention proposes to solve the problem of calibration of the auxiliary power supply of the feed ramp of the disengaging mechanism.

More specifically, the subject of the invention is a device for deactivating at least one cylinder of a multi-cylinder type internal combustion engine, comprising means for decommissioning the intake or exhaust valves of said cylinder. actuated by a fluid under pressure, a pressurized fluid supply circuit, a controlled solenoid valve and a secondary circuit connecting said solenoid valve to said means for decommissioning, auxiliary supply means for supplying fluid to the secondary circuit outside periods of actuation of said means for decommissioning, characterized in that auxiliary supply means comprise a valve for maintaining the pressure in the auxiliary supply means below a threshold pressure.

According to certain features, the secondary circuit comprises leakage passages of said fluid, especially at the level of the means of decommissioning and / or at a nozzle provided in the secondary circuit, and said auxiliary supply means are shaped so that their feed rate compensates for the flow of the leakage passages.

According to other features, the intake or exhaust valves of said cylinder are actuated by means of hydraulic play-compensated stops fed by a feed ramp and said auxiliary power supply means provide communication between the feed ramp. power supply and the secondary circuit.

According to other features, the auxiliary power supply means consist of a conduit forming a communication from the supply ramp and to the secondary circuit, said duct comprising at least a first Venturi capable of generating a pressure drop and a derivation upstream of said Venturi with the valve. According to other characteristics, the conduit comprises a second Venturi capable of generating a pressure drop upstream of the bypass provided with the valve.

According to other features, the conduit communicates with the pressurized fluid supply circuit by means of the bypass provided with the valve.

According to other features, the hydraulic play catchers incorporate the means for decommissioning the valves.

According to other features, the device for deactivating at least one cylinder of an internal combustion engine comprises a filter upstream of the auxiliary supply means, intended to limit the fouling of said auxiliary supply means.

FIG. 1 represents a schematic view of a device known from the prior art for deactivating two of the four cylinders of an internal combustion engine.

Figure 2 shows a schematic view of a device for deactivating two of the four cylinders of an internal combustion engine, according to the present invention.

Referring to Figures 1 and 2, there is shown the exhaust portion of a camshaft and latch distribution of an internal combustion engine having four cylinders in line 16, 17, 18, 19.

Conventionally, and not shown in Figures 1 and 2, the translational movement of a valve that alternates its opening and closing, operates through a lever, called latch. One of the ends of the pawl is in fact in contact with the valve stem and admits an oscillation movement as a function of the rotation of the cam carried by the camshaft. The other end of the pawl serves as a pivot point and rests on a stop. So that the ends of the latches, not shown in the figures, remain in abutment on their stop, it is advantageous to adjust the contact in using hydraulic stops to catch play. The play catch is then fed by a fluid, in this case oil, which is conveyed by the ramp 4.

According to FIGS. 1 and 2 and in accordance with the invention, the hydraulic play-catchers 8, 9, 10, 11, respectively comprise means of decommissioning (20, 21, 22, 23), also called means. of clutches, also powered by a fluid, in this case the oil, which is conveyed by the ramp 5. Thus, only the cylinders 17, 18 are deactivatable. The ramp 4 which feeds the hydraulic stops with play catch-up

6, 7, 8, 9, 10, 1 1, 12, 13 is maintained filled by means of a feed ramp 15, which itself is fed by the main oil supply line of the motor cylinder head, not shown. in the figures. The ramp 5, which supplies the clutch mechanisms 20, 21, 22,

23, is fed intermittently by means of a communication 14 with the ramp 4. Advantageously, the communication 14 is a solenoid valve. More specifically, when it is necessary to disable the valves, the solenoid valve 14 opens so as to let the oil from the ramp 4 to the ramp 5, where the pressure is initially lower. When the pressure in the ramp 5 exceeds a calibrated threshold pressure Pseuil, the disengagement mechanisms 20, 21, 22, 23 are activated so as to disengage the hydraulic compensating stops play (8, 9, 10, 1 1). In this way, the valves are rendered inactive. In practice the pressure Pseuil is of the order of 0.7 bar.

When it is necessary to reactivate the valves, the solenoid valve 14 closes in such a way that the pressure in the ramp 5 descends below that of the calibrated threshold Pseuil so that the clutch mechanisms 20, 21, 22, 23 are no longer enabled. Note that the pressure drop is induced by the leaks existing at the disengaging mechanisms 20, 21, 22, 23 and at a nozzle 24 which serves to degass the fluid circuit in the ramp 5. In order to control the volume of the leaks existing at the disengagement mechanisms 20, 21, 22, 23 and the nozzle 24, the invention consists in maintaining a continuous communication between the ramps 4 and 5, while controlling the flow rate oil from the ramp 4 to the ramp 5. Indeed, the leaks at the disengagement mechanisms 20, 21, 22, 23 and the nozzle 24 allow to lower the pressure in the conduit 5 and thus to reactivate all the cylinders. But do not completely empty ramp 5 as this will increase the duration of the next deactivation. According to our invention and as described in Figure 2, the auxiliary power supply means consist of a conduit 35 communicating the ramp 4 and the secondary circuit 5, and provided with a first Venturi 32 capable of generating a pressure drop of so that the pressure of the fluid in the ramp 5 is always lower than the pressure in the conduit 35 when the solenoid valve 14 is closed. In addition, the conduit 35 communicates with a bypass 33 with a valve 34 upstream of said Venturi 32. Said bypass 33 with the valve 34 has the function of maintaining the pressure in the conduit 35 below the Pseuil value. Thus, the pressure in the ramp 5 can not cross the value Pseuil just because of the supply via the Venturi 32. As a result, the clutch mechanisms 20, 21, 22, 23 can not be activated inadvertently.

Advantageously, the bypass 33 with the valve 34 communicates the conduit 35 with the supply circuit 15 with fluid under pressure so as to recover the fluid under pressure and therefore to minimize the losses by pumping.

In the preferred variant of the invention shown in FIG. 2, a second Venturi 31 is additionally disposed in the duct 35 upstream of the bypass 33 so as to generate a pressure drop in the duct 35. The Venturi 31 thus allows to have sufficiently high pressures in the ramp 4, that is to say greater than Pseuil, to supply the mechanisms catch-up play 6 to 13. In practice these pressures are of the order of 1 bar. Thus, when the solenoid valve 14 is closed, the ramp 5 is fed via the duct 35 and the venturi 32 assisted by the valve 34 ensures a pressure in the ramp 5 lower than Pseuil. The nozzle 24 of the ramp 4 is optional insofar as the degassing is effected via the valve 34. When the solenoid valve 14 is open, the pressure in the ramp 5 increases so as to exceed the value Pseuil to deactivate the cylinders. In addition, the pressure in the ramp 5 being greater than that in the conduit 35, the venturi 32 then allows the degassing of the ramp 5 to the conduit 35. The nozzle 24 of the ramp 5 is thus optional. In summary, the duct 33 acts as a buffer volume making it possible to have sufficient pressure for the catch-up mechanisms 6 to 13 fed by the ramp 4, while controlling the level Pseuil to be respected in the duct 5.

Advantageously, it is advantageous to have a filter 25 upstream of the auxiliary supply means 30, in order to limit the fouling of said auxiliary supply means.

As a result, the invention makes it possible, with few constraints concerning the calibration of the Venturi, to maintain a minimum pressure in the feed ramp of the clutch mechanism and consequently to reduce the response time at the first time. deactivation of the cylinders.

Claims

1. Device for deactivating at least one cylinder (17, 18) of a multi-cylinder type internal combustion engine, comprising means for decommissioning (20, 21, 22, 23) of the intake valves or exhausting said cylinder operable by a pressurized fluid, a pressurized fluid supply circuit (15), a controlled solenoid valve (14) and a secondary circuit (5) connecting said solenoid valve (14) to said disengaging means service (20, 21, 22, 23), auxiliary supply means (30) for supplying fluid to the secondary circuit (5) outside the periods of operation of said decommissioning means (20, 21, 22 , 23), characterized in that the auxiliary supply means (30) comprise a valve (34) for maintaining the pressure in the auxiliary supply means (30) below a threshold pressure (Pseuil).

2. Deactivation device according to claim 1, characterized in that the secondary circuit (5) comprises leakage passages of said fluid, especially at the level of the means of decommissioning (20,

21, 22, 23) and / or at a nozzle (24) provided in the secondary circuit (5), and in that said auxiliary supply means (30) are shaped to compensate for their feed rate. partly the flow of the leakage passages.

3. Device according to any one of claims 1 or 2, characterized in that the intake or exhaust valves of said cylinder (17, 18) are actuated by means of hydraulic stops to compensate clearance (8, 9, 10, 11) fed by a ramp (4) and in that said auxiliary power supply means (30) provide communication between the feed ramp (4) and the secondary circuit (5).

4. Device according to claim 3, characterized in that the means (30) consist of a duct (35) forming a communication from the ramp (4) to the secondary circuit (5), said duct (35) comprising at least one first Venturi (32) capable of generating a pressure drop and a bypass (33) provided with the valve (34) upstream of said Venturi (32).

5. Device according to claim 4, characterized in that the duct (35) comprises a second Venturi (31) adapted to generate a pressure drop upstream of the bypass (33) provided with the valve (34).

6. Device according to claim 4 or 5, characterized in that the conduit (35) communicates with the pressurized fluid supply circuit (15) by means of the bypass (33) provided with the valve (34).

7. Device according to any one of claims 3 to 6, characterized in that the hydraulic catch-up stops (8, 9, 10, 1 1) incorporate the means of decommissioning (20, 21, 22, 23) valves.

8. Device according to any one of the preceding claims, characterized in that it comprises a filter (25) upstream of the auxiliary supply means (30) for limiting the fouling of said auxiliary supply means.