VALVES

The present invention concerns, in general, the sector of components for endothermic engines; in particular, the invention refers to a control, driving and checking system for machine valves.

Traditionally, the handling of the valves - e.g. the suction/exhaust valves of internal combustion engines - has been mainly managed as function of the cam profile geometry, which regulates their height of lift.

Unfortunately, such method is affected by excessive rigidity in its mode of control, which manifests poor flexibility in converting the rotary motion and transmitting the axial mode as function of the different operating conditions.

Systems characterized by an increasingly greater modularity in the height of lift were recently designed and developed. Mechanical, electrical and electro-hydraulic systems have been progressively introduced in order to improve the phasing process (e.g. trying to control and manage the advanced and delayed opening and closing of the valves) and optimize as much as possible the engine performance, avoiding - at least along some parts of the operating cycle - losses in terms of thrust and - consequently - of overall efficiency.

An example of known solution, which uses handling means of the electrical drive valve, is described in EP 2027369 Bl, which illustrates a system where a rocker arm oscillates by means of an electrical motor, alternatively engaging one or more valves and generating their vertical transfer. The return of the valve to retracted position is generated by a spring.

However, the lowering movement of the rocker generates an impact on the valve. In order to prevent such issue, the valve could be rigidly connected to an end of the rocker arm. Nevertheless, even this solution would not allow the valve, which is covering a linear stroke, to cover in an optimal way the arch trajectory of the rocker arm, or to dampen and control the lifting height of the valve. Documents US-A-2316790, WO-A1-2014/202566, EP-

Al-0416794, US-A-1239933, JP-A-S57195807, EP-A1-

1580405 and JP-A-S61244810 disclose general control systems according to the preamble of Claim 1.

One of the purposes of this invention is to remedy the aforementioned issues.

In order to achieve such result, a control, driving and checking system for machine valves includes an oscillating element (preferably, a rocker arm) of the active/adapting type, which supports the sliding of an extractable pin, to which the valve is connected. This way, the raising/lowering motion of the oscillating element primes the alternative motion of the valve, and the sliding pin either comes out of the element or comes back into it, adapting the arch trajectory of the latter to the rectilinear trajectory of the valve .

Furthermore, the housing the connection pin slides within can be at least partially filled with fluid (preferably oil) , in order to facilitate the sliding of the pin and/or generate a dampening effect, thus contributing to improve the adapting behavior of the oscillating element. Furthermore, in compliance with the preferred embodiment, the pressure and/or quantity of fluid within the sliding housing of the pin can be actively adjusted, e.g. adding fluid to the housing or reducing it.

Preferably, as it will be better appreciated further on in this description, the driving means that provide the oscillation to the oscillating element is an electrically-operated actuator (e.g. of the linear or rotary type) , instead of the rod/cam systems of the traditional valve lifters. The system developed in compliance with this invention allows obtaining - among other things - the following advantages, depending upon the forms of development:

- better control of the essential lift height stages;

valve stroke coordinates controlled in continuous mode;

- high positioning and operating accuracy;

instantaneous control of the valve stroke, by means - for instance - of a permanent magnet DC motor, provided with an appropriate position sensor;

valves of a more reduced size as compared to those that are currently being used;

reduction of the active stress on the valve- actuator combination thanks to the introduction of the telescopic rocker arm;

self-compensation of the valve length in case of thermal expansion and wear phenomena, thanks to the instantaneous control of the valve position during the different stages of the combustion process, by means of the instantaneous total control of the lift height of the valves as a function of the task requirements ; - better management of the advances and delays in the combustion cycle;

- the movement of the valves can be separated from the combustion engine shaft rotation speed, with a subsequent increment of the overall efficiency in the combustion chamber; continuous control of the valve stroke/lift height combination with the variation of the actual engine load;

variable compression ratio;

- maximized use of the max. C02 rated potential;

- more contained leaks of potential C02 during the operation of the car as related to its drivability characteristics;

- reduction in oil consumption thanks to a lower heat exchange and to a reduced number of components to be lubricated;

- independent activation and control of the cylinders;

- divisible cylinders during both the active and passive phases;

- adjustable engine brake;

- ability to distribute the loads in a diversified mode between the cylinders;

- lower emissions at exhaust thanks to the ability of turning on or off one or more cylinders as a function of the task's requirements ;

the solution can be extended to different types of fuel depending upon different types of operational cycles (this solution is particularly suitable for the Miller and Atkinson cycles);

- better adaptability to the environmental and service conditions;

lower number of components and simplified layout; possible elimination of camshaft, retracting springs for hysteresis compensation, bowls and plates, rods, pulleys, belt, etc.); better design and - consequently - higher productivity;

partial elimination of some moving organs in case of a reduction of the stressing loads on the remaining mechanical components;

significant reduction of friction and wear through the use of the tribological properties of the contacts (e.g. screw/cross-head nut stroke sphere contacts) ;

lower power absorbed;

lower lubrication; reduced facilitated maintenance and fine tuning;

- possible electronic management of the operational phases; better control of the ignition phases;

- better communication and interaction with the surrounding apparatuses, through evolved checking systems (on-board diagnosis) ;

better control of the emergency stages and - in general - substantial increase of the safety levels ;

the introduction of the telescopic oscillating element compensates the elimination of the spring on the valve;

improved driving quality of the vehicle;

significant reduction of the weights and consequently - reduced consumption and emissions of polluting agents;

- the possible elimination of the camshaft corresponds to the elimination of the "parasite" torsion moments absorbed by the cams and - consequently - reduction of the energy requirements, thus - finally - a further reduction of consumption;

- more regular accurate motion of the valves, which allows optimizing the combustion process in the cylinder chamber;

lower friction because of a lower number of moving organs;

faster, more efficient start-up;

reduction of vibrations and noise;

lower power absorbed to operate and control the auxiliary organs;

- possible use of different fuels on the same engine;

possible use of appropriate software for the rational use of the different fuels that can be used on the same engine (e.g. natural gas/gasoline etc.);

cost-effective absence of the camshaft and of the relevant machining;

- elimination of the valve handling kinematic chain components;

improvement of the overall engine layout thanks to the possible reduction of the cylinder head; reduction of weight and of the moving organs thanks to the low complexity of the system ensured by the minimum number of components required as compared to the currently developed solutions ;

lower need of lubrication oil;

lower wear of the components;

significant savings in terms of production and processing cost, components, manufacturing, assembly, fine tuning and calibration thanks to the elimination of manufacturing costs;

improvement of the useful torque curve;

- high sensitivity of the adjustments as related to the tolerances applied;

improvement of the overall efficiency, thanks to the increased operational interval;

increased torque and efficiency;

- greater accuracy and rigidity of the electromechanical actuators as compared to the equivalent systems, which are operated by electro-hydraulic actuators;

faster response and execution of the electro mechanical actuators as compared to the equivalent systems, which are operated by electro-hydraulic actuators;

possible conversion between different adjustment modes of the valve systems depending upon the operational requirements of the task; management of the lift height and of the phase performed through the use of only one actuator with the subsequent reduction of transient phenomena during the ignition phase;

- better control of the loads and subsequent reduction of the engine size;

cost-effective presence of an electro mechanical system, which does not require any oil chamber, solenoid valves, pumps or sensors for pressure and temperature controls;

the system can be managed using the ECU's currently in use;

only one actuator can operate/control two similar valves at the same time.

The aforementioned purposes and advantages and more - are achieved by an aspect of the invention, i.e. by a system whose characteristics are defined in claim 1. Preferential forms of development of the invention are defined in the dependent claims.

The functional and structural characteristics of some preferred embodiments of a control, driving and checking system in compliance with the invention are described below. Reference is made to the enclosed drawings, where: - figures 1A and IB are respectively a schematic front view and a schematic section view of a system in compliance with one embodiment of the invention, which shows a drive system which includes a linear actuator that engages a telescopic rocker arm, connected to the valve;

- figure 2 is a schematic view of a cylinder- piston unit, which incorporates a pair of driving systems in compliance with the development form reported in figure 1, and of a possible diagram of the electrical control circuit of the driving means;

- figure 3 is a front schematic view of a system in compliance with a further embodiment, which shows a drive system, including a pair of linear actuators, which incorporates a telescopic rocker arm whose third arm is connected to the valve;

- figure 4 is a schematic section view of a system in compliance with the embodiment shown in figure 3;

- figure 5 is a schematic view of a cylinder- piston unit, which incorporates a pair of driving systems in compliance with the development form reported in figure 3, and of a possible diagram of the electrical control circuit of the driving means;

- figures 6A and 6B are respectively a schematic front view and in horizontal section of a system in compliance with a further embodiment, which shows a drive system which includes a rotary actuator that engages a telescopic arm, connected to the valve;

- figure 7 is a schematic top view of an alternative embodiment of the system shown in figure 6A; and

- figure 8 is a schematic view of a cylinder- piston unit, which incorporates a pair of driving systems in compliance with the development form reported in figure 6A, and of a possible diagram of the electrical control circuit of the driving means;

Before explaining in detail a plurality of forms of development of the invention, it must be clarified that the application of the invention is not limited to the manufacturing details or to the configuration of the components presented in the description hereinafter or shown in the drawings. The invention can take other forms of development and can be implemented or practically developed in various ways. It must also be understood that the expressions and terminology have a descriptive purpose and should not be meant as a limitation.

Referring as an example to figure 1, a control driving and/or checking system 9 for engine valves includes at least a valve 10, which is moving between two positions and able to allow or prevent the passage of a flow through a duct, and an oscillating element 12, to a first end of which the valve 10 is connected. The oscillating element 12 can oscillate between two positions, so that it generates a transfer of said valve 10 between the opening and closing configurations of the duct.

The system 9 includes at least one means of driving 14, movable between two positions. The driving means 14 engages the oscillating element 12, so that it makes it oscillate.

The valve 10 can be moved under the action of the oscillating element 12 by means of a connecting pin 16, which includes a rod 16a located slide wise inside said oscillating element 12, so that the transfer of the valve 10 causes a sliding of the stem 16a along the oscillating element 12.

The valve can be kept in contact against the connecting pin 16, for instance by means of an elastic means (in compliance with a not shown mode) , or it can be solidly connected to said pin

16 (e.g. an end of the valve stem can be mated to an eyelet of the pin that hangs from the oscillating element, like in the shown examples) .

In compliance with one embodiment - which is shown as an example in figure 1, the valve 10 is connected to pin 16 by means of a joint 11, mated to pin 16, where the joint 11 supports an end of the valve 10.

Appropriately, the rod 16a of the connection pin 16 slides within a housing 12a extended along the oscillating element 12; the housing 12a is at least partially filled with a fluid (preferably engine oil) .

Preferably, the pressure and/or the quantity of the fluid within the housing 12a can be adjusted. Thanks to the controlled filling with fluid (appropriately, oil coming from the internal combustion engine) in housing 12a of the connection pin 16, the thrust exerted by the driving means 14 on the oscillating element 12 and or from the latter to the valve 10 can be increased or dampened.

In compliance with a embodiment (which is not shown) , part of the fluid in the housing 12a can be sent to the joint 11 to make it rotate around its lengthwise axis (e.g. by means of an impeller incorporated to the joint, which is thrust by the rate of the fluid coming from said housing 12a) . In this way, the joint 11 could drag in rotation the valve 10, whose rotation would allow for the optimum distribution of heat on the head of the valve 10.

In compliance with a preferred embodiment, the driving means 14 is electrically operated. In compliance with one embodiment, the oscillating element 12 is configured as a rocker arm, with at least two oscillating arms 13 around a fulcrum 12b, where the valve 10 and the driving means 14 are connected to the ends of the respective arms 13.

As an option, the arms 13 of the rocker arm are of different length, as a function - for instance - of the nature and entity of the loads to be transmitted to the valve/s 10.

In compliance with one embodiment (which is shown as an example in figures 1A, IB and 2), the driving means 14 is a linear electro-mechanical actuator connected to the oscillating element 12 by means of a further connection pin 16 and at least partly extractable from said oscillating element 12, where the linear electro-mechanical actuator can provide an alternative motion to the associated connection pin 16 along its own lengthwise axis.

As an option, the linear electro-mechanical actuator is a screw actuator.

In compliance with one embodiment (which is shown as an example in figures 3 through 5) , the system 9 includes a pair of driving means 14, connected to the ends of the respective two arms 13 of the oscillating element 12, which are respectively coaxial. In this configuration, the valve 10 is connected to a third arm 13, which is substantially perpendicular to the first two ones.

Appropriately, one of the two actuators is allocated to give the movement to the rocker arm 12 in one direction, whilst the other actuator is allocated to give the movement to the rocker arm 12 to the opposite direction, so that either actuator adjusts one lifting stage of the valve 10.

In compliance with one embodiment (which is shown as an example in figures 6A through 7), the oscillating element 12 is a single arm 13 extended along the a direction perpendicular to the axes of the valve 10; said arm 13 can oscillate around a fulcrum 12b, to which the driving means 14 is connected.

In compliance with one embodiment, the driving means 14 is a rotary driving means, able to give an oscillation to the oscillating element 12 in correspondence to fulcrum 12b of the latter.

Appropriately, the rotary driving means includes a first motor 15a to give a rotation to the oscillating element 12 in one direction, and a second motor 15b to give a rotation to the oscillating element 12 in the opposite direction.

In compliance with one embodiment, the rotary driving means 14 is integrated to the oscillating element 12. For instance, in compliance with the development form shown in fig. 7, the first motor

15a is integrated to the oscillating element 12, whilst the second motor 15b engages the pin of said oscillating element 12 from the outside of the latter .

The rotary driving means can oscillate an oscillating element 12 both in the form of a single arm 13 (as shown in figure 6A) and in the form of a rocker arm with two or more arms (in compliance with a mode that is not shown) .

An electronic control unit can be provided to control the movement of driving means 14 and/or the filling of fluid into the housings 12a of the sliding pins 16. It can also be provided with position sensors and transducers, appropriately associated to the driving means 14, to adjust their operations.