EP1143116B1 - Internal combustion engine - Google Patents

Abstract

The movement of the inlet valve in opening or closing w.r.t the valve seats (10,13), is controlled using an electromagnetic actuator (15), while that of the exhaust valve is controlled by an assembly (16) including a lever (28) controlled by a cam (27) shaft (26), this assembly being independent of the electromagnetic actuator. The IC engine has an inlet valve (6) and an exhaust valve (7) co-operating respectively with valve seats (10,13) fitting on the cylinders (2).

Description

The present invention relates to a combustion engine internally for a motor vehicle and concerns more especially a particular arrangement of the valves intake and exhaust associated with the cylinders of this motor, as well as means for actuating these valves.

A classic solution in combustion engines internally for a motor vehicle consists of ordering the movement of the valves at the intake and the exhaust at means of a camshaft that operates directly or indirectly, for example using rockers acting on their stem, these valves against springs of reminder to cause the displacement of these valves vis-à-vis their seat by opening or closing cylinders in the cylinder head of the engine and, according to the case, allow the admission of the combustible mixture injected or otherwise allowed into these cylinders or ejection burnt gases, the various valves of the engine being ordered in sequence to perform the multi-cycle time of this engine.

Another, more modern solution is to remove the camshaft, whose action on the valves is purely mechanical, and to substitute a set of electromagnetic distribution where, schematically, each valve stem is associated with a metal frame that is struggling back and forth in the gap of an electromagnet, with spring return of the valve in a position intermediate average.

Particular embodiments of such actuators electromagnetic valves of a combustion engine are, for example, the subject of patent applications 99 09618 of 23 July 1999, 00 01321 of the 2nd of February and 00 01492 of February 7, 2000 in the name of the plaintiff. In particular, these patent applications relate to improvements to an electromagnetic actuator of this type, whose interest is among others to easily disable some engine cylinders during of the cycle, that is to say to put them out of service when some times of the latter depending on the charging conditions and engine speed, providing a reduction motor consumption without affecting its performance. performance.

In particular, the aforementioned electromagnetic actuators allow to conceive and realize in a very effective a variable distribution, modifying immediately the opening and closing angles of valves, that is to say, during the cycle, the precise moment where each valve, both admission and exhaust, opens or closes, this moment being able to thus be optimally adapted according to the needs.

The main gain on the overall engine consumption comes from the implementation of this type of actuator and the distribution he makes in the cylinders when he is fitted on an engine intake valve, the checking the openings and closures of this valve to better adjust the air load that is injected into the cylinder, in the same way as realizes the butterfly of the carburettor of a gasoline engine, with the advantage that it avoids any pumping inherent in this last solution, provided that the opening angles and closing the valve are suitably wedged.

In full charge, the variable setting of the angles of the intake valve makes it possible to benefit fully from internal aerodynamic effects of the intake manifold and to have, therefore, a maximum filling. The maximum torque curve of the motor is then strongly improved, especially at low speed. This results in a gain immediate on engine consumption in partial load and also on its maximum torque curve.

Other benefits come from load control directly through the valves with a command presenting an almost instantaneous response time, in which the inertia of moving parts is greatly reduced by compared to the classical solution. This results in a decrease of the reserve of advance with the necessary lighting in the usual engines and allows operation in conditions where this advance can be perfectly optimized.

On the other hand, if the same solution of actuators to control electromagnetic is also considered for the valves exhaust, thus eliminating the entire mechanism of conventional camshaft and thereby simplifying the mechanical structure of the engine due to the suppression means of training this tree, it increases without doubts the possibilities of adjusting the movement of the valves including the adjustment of their opening angle and closing, allowing in a more efficient way to disable some of the cylinders during the cycle of engine, regardless of the load of it.

So, in a four-cylinder engine, it turns out interestingly, when the engine load is low, that is to say when the amount of air admitted per cycle is weak, disable two cylinders by realizing no only the closing of the intake valves and exhaust of these cylinders but also by cutting injection and ignition, this solution being revealed particularly effective in reducing significant engine consumption.

In this case, the two other engine cylinders that stay active, work with more powers high (usually about twice as high) and so with better yields.

Finally, in the solution where all the valves are controlled by electromagnetic means, the control opening and closing angles of each of these valves makes it easy to adjust the gas rate residual in each cylinder and reduce the levels of pollutants in the flue gases.

However, the implementation of this solution in which the motor comprises only electromagnetic actuators for all the intake and exhaust valves, a solution known in the art under the term " Camless ", poses significant technical problems. for its implementation.

Indeed, with regard to an exhaust valve, we immediately understand that the actuator, which controls directly the armature carried by the stem of the valve, is placed in an environment where the temperature is significantly higher than the one surrounding the same actuator when associated with an intake valve.

The induced heating results in an acceleration of the Aging of the actuator, in particular winding electromagnet and electrical insulators he includes.

Moreover, contrary to what happens for a intake valve, opening a valve exhaust, especially when the engine load increases, requires significant energy to overcome the residual pressure in the cylinder, which can reach up to 8 bars at the time of opening. To open this valve, by opposing this pressure, it is necessary that the actuator can provide an effort whose order of magnitude represents the product of the surface of the valve by the difference between the pressure in the cylinder and that which prevails in the exhaust manifold, which is relatively close to the atmospheric pressure.

The energy required requires the current in the coils of the electromagnet be considerably increased, hence a heat dissipation in these coils that grows with the square of intensity, further increasing the temperature of the environment of this actuator.

In practice, the demand for electricity is such that it exceeds the capabilities of the conventional alternator equipping conventional motor vehicles, the solution requiring unconventional architectures generators (for example two alternators coupled in the case of a 12 V onboard network or alternator of 42V coupled to the 12V grid), which significantly increases the cost price of the solution.

Finally, because of the residual pressure in heavy load that the exhaust valve must counter during the opening, it results in a reduction of the performances of the motor. Indeed, the transition from the closed state to the state open valve requires a transition time increased, which is penalizing at high speed and reduces the efficiency of the extraction of the burned gases from the cylinder, the maximum engine power is thus more limited.

The subject of the present invention is a new arrangement of means performing the actuation of the intake valves and exhaust of an internal combustion engine for vehicle, which overcomes these disadvantages.

For this purpose, the engine considered as described in document DE 19511880), comprising at least one intake valve and at least one exhaust valve cooperating respectively with seats arranged on each of its cylinders, the movement of the intake valve to opening and closing with respect to its seat being controlled and controlled by an actuator electromagnetic, while the exhaust valve is controlled by a set comprising at least one system mechanical mechanism such as a lever or the like manipulated by a camshaft, this assembly being independent of the electromagnetic actuator, is characterized in that, to increase its performance, it includes means during a cycle, to deactivate at least one of its cylinders, by simultaneously closing on it the intake valve and exhaust valve, maintained each applied to his seat.

Also preferably, closing the valve intake and exhaust valve is accompanied by the cutting of the injection of the fuel mixture into the cylinder and ignition in this cylinder.

For this purpose and according to a particular characteristic of the invention, the lever operated by the camshaft for control the exhaust valve, acts simultaneously on a stop capable of providing a variable reaction force such that the camshaft causes, as the case may be, the control of the exhaust valve or the depression of the stop, in which case the valve remains applied to its seat, the cylinder being deactivated.

Other features of an internal combustion engine including the control of the intake and exhaust valves is carried out according to the invention will appear again through the following description of an example of realization, given for information and not limitation, in reference to the single figure of the accompanying drawing which illustrates schematically a partial sectional view of the cylinder head of the motor with the actuating means of these valves.

In this figure, the reference 1 denotes schematically a part of the cylinder head of the engine, in particular to the right of a cylinder 2, connected to two pipes, respectively 3 and 4, the first being reserved for admission into this cylinder 2 of a mixture of gasoline and air, the second to the exhaust burned gases after ignition and combustion of this mixture.

The injection of the mixture into the cylinder can be carried out in any appropriate way, which in itself does not matter to the invention, for example using an injector 5 schematically illustrated on the drawing and mounted in communication with intake manifold 3.

The cylinder 2 is associated with at least one valve 6 and at least one exhaust valve 7. In the figure, the intake valve 6 has a head 8 extended by a rod 9, the head 8 being supported on a seat 10 provided on the cylinder head 1, to the right of the link between the intake manifold 3 and the cylinder 2.

Similarly, the exhaust valve 7 has a head 11, a rod 12 integral with this head and a seat 13 provided at the end of the tubing 4 by which the flue gases escape.

A candle or similar ignition member 14 is mounted on the cylinder head 1 to the right of the cylinder 2, so as to allow the creation in the cylinder of the spark causing the combustion of the mixture, according to a process in itself perfectly known.

According to the invention, the two valves 6 and 7, respectively of intake and exhaust, are separately associated, the first to an actuator electromagnetic 17, the second to a device fully mechanical camshaft 16, independent one the other.

The electromagnetic actuator which controls the intake valve 6 and in particular the control of its deflections vis-à-vis its seat 10, consists of known manner and in particular as described in the requests for aforementioned patent in the name of the applicant, by a electromagnet 17 itself consisting of two coils 18 and 19 between them an air gap 20, delimiting a relatively narrow cavity in which can struggle a metal frame 21, secured to a support 22 axially extending the rod 9 of this valve. of the return springs, respectively 23 and 24, are associated to the rod 9 and the support 22.

The spring 23 tends to close the valve and the spring 24 to open it: in the absence of current, the valve is half opened. When a current flows through the upper coil 18, she draws towards her the metal frame 21, closing thus the valve. When a current flows through the coil lower 19, the latter attracts towards her the frame 21 and the valve opens.

The mechanism 16, which actuates the exhaust valve 7, essentially comprises a rotary shaft 26 having in its outer surface a projecting cam 27, suitable for come act when rotating the shaft, on a lever or analogous 28 in support at 29 on the end of the rod 12 of the valve 7. A spring 30 is provided to ensure the reminder of the head 11 of the latter on its seat 13, when the cam 27 is not in contact with the lever 28.

The lever 28 is supported on the other hand by an abutment 31 whose positioning is adjustable, consisting in particular in the example shown, by means of a hydraulic system consisting essentially of a piston, connected to the stop 31, lying inside a cylinder whose cavity 32 is permanently fed by a pipe intake 33 of an incompressible fluid, in particular consisting of engine lubricating oil.

The oil contained in the cavity of the cylinder can the case appropriate to evacuate out of it by another pipe 34, on which is provided a solenoid valve order 35.

In normal operation, the lever 28, resting on the stop 31, causes each passage of the cam 27 to the shaft 26 a force on the rod 12 of the valve 7 to against the spring 30, realizing the opening of the valve which is detached from its seat 13, thus ensuring the communication between the cylinder and the tubing 4 for the exhaust of burnt gases.

However, the means thus implemented to control respectively the two valves 6 and 7, allow to easy way to deactivate cylinder 2 if necessary now closed during a cycle of operation, the heads 8 and 11 of the valves remaining applied on their respective seats 10 and 13.

With regard to the electromagnetic actuator 15, immediately conceives that the deactivation of the valve 6 admission can be obtained in the easiest way by electrically feeding the coil 18.

On the other hand, for mechanism 16, the same function can be performed by opening the solenoid valve 35 on the channel 34 so as to reduce the pressure in the cavity 32, the lever 28, during the passage of the cam 27, pushing the stop 31, without exerting any effort on the rod 12 of the valve which remains thus closed thanks to the effort of the return spring 30.

The inventors have found that the system of the invention allowed to reduce the engine consumption and that the deactivation of the cylinder made it possible to increase the gain in consumption, especially when the the engine is low, of the order of 700 to 3500 revolutions per minute, the control of the hydraulic stop not requiring at these rotations particularly switching times limited.

In parallel, one can of course, when the cylinder 2 is deactivated, its valves remaining closed, delete injection and turn off the ignition.

This produces an internal combustion engine of simple design, which combines the advantages of a electromagnetic actuator and a conventional actuator to camshaft, purely mechanical, the implementation these two solutions, respectively on the intake and exhaust valves, which only imply reduced cost, not leading to a limitation on the Possibilities for steering the crossing, that is to say on the choice of when, under normal conditions, each valve exhaust closes as the valve opens intake.

Of course, it goes without saying that the invention is not limited to to the embodiment more specifically described above with reference to the accompanying drawings; she embraces on the contrary all variants.

Claims (3)

1. Internal combustion engine for a motor vehicle, comprising at least one inlet valve (6) and at least one exhaust valve (7) co-operating respectively with seats (10, 13) made on each of its cylinders (2), the movement of the inlet valve on both opening and closing with respect to its seat being controlled and monitored by means of an electromagnetic actuator (17), while the exhaust valve is controlled by an assembly (16) comprising at least one mechanical system such as a lever or the like (28) operated by a cam (27) shaft (26), this assembly being independent of the electromagnetic actuator, said engine being characterised in that, in order to increase its output while deactivating, during a cycle, at least one of its cylinders, the engine comprises means (18) for controlling the closing of the inlet valve (6) and means (32, 34, 35) for controlling the closing of the exhaust valve (7) so as to keep the valves (6, 7) applied simultaneously on their seats.
2. Engine according to Claim 1, characterised in that the closing of the inlet valve (6) and of the exhaust valve (7) is accompanied by the cutting off of injection of the fuel mixture in the cylinder (2) and of ignition in this cylinder.
3. Engine according to Claims 1 and 2, characterised in that the lever (28) operated by the cam (27) shaft (26) for controlling the exhaust valve (7), acts simultaneously on a thrust bearing (31) capable of providing a variable reaction effort such that, depending on the case, the camshaft causes the exhaust to be controlled or the thrust bearing to be depressed.

Images