ITMI20091799A1 - EGR VALVE FOR LOW PRESSURE TYPE APPLICATIONS, IN THE TECHNIQUE OF CONTROLLED RECIRCULATION OF COMBUSTIAL GASES IN INTERNAL COMBUSTION ENGINES. - Google Patents

Description

EGR VALVE FOR LOW PRESSURE APPLICATIONS, IN THE TECHNIQUE OF CONTROLLED RECIRCULATION OF COMBUSED GAS IN INTERNAL COMBUSTION ENGINES

DESCRIPTION

FIELD OF INVENTION

The invention relates to a system that allows to implement the controlled recirculation of exhaust gases in a supercharged diesel internal combustion engine equipped with systems that carry out an exhaust gas treatment (as in the case of catalysts and particulate filters or DPF ) in order to clean them before putting them in the atmosphere.

More precisely, the technical field within which the invention is located is that of low pressure exhaust gas recirculation systems, hereinafter indicated with the expression EGR (acronym of â € œExhaust Gas Recyclingâ € or â € œExhaust gas recirculationâ €) Long Route.

The recirculation of flue gases is a very effective method for lowering the combustion temperature and the consequent reduction of nitrogen oxides. It allows, in fact, to dilute the intake air charge with the exhaust gases, previously produced, which do not participate in the combustion reaction, or rather participate in it only for that rate defined as â € œincombustedâ €. The use of EGR gases is particularly useful at medium-low engine speeds; while it is instead counterproductive in all those situations in which greater power is required; in this case the EGR flow must be interrupted, and it is essential that the valve in charge has an optimal seal, with practically no leakage

The advantages of Long Route EGR systems are many:

a) favor the reduction of nitrogen oxides;

b) the recirculated gases are almost free from carbonaceous particles as they are taken downstream of the DPF;

c) the recirculated gases have a lower temperature than the one leaving the combustion chamber;

d) dilution of the fresh batch;

e) system easily applicable to the engine configuration; In view of these advantages, the application of the technique of controlled recirculation of flue gases by means of Long Route type systems presents considerable difficulties. In this regard, it is observed that the path of the exhaust gases is articulated between low pressure points and this requires that the circuit be characterized by a high permeability to the gas flow. In this context, conventional poppet valves have obvious limits of applicability. In fact, although these valves guarantee a high resistance to leakage, on the other hand they are not very efficient in terms of the maximum flow rate processed and this is due both to the contained value of the outflow coefficient and to the limits imposed by the maximum lift of the valve itself.

For EGR applications of the Low Pressure type, that is the recirculation of exhaust gases at low pressure, systems are therefore necessary that allow the processing of high gas flow rates and which, at the same time, guarantee a high resistance to exhaust gas leakage. The performance of Long Route EGR systems can be considerably increased if it is possible to influence the fluid dynamics of the intake and / or exhaust systems in the most appropriate and functional way.

The present invention proposes innovations regarding: the system for implementing the controlled recirculation of exhaust gases at low pressure, the way to optimize the performance of the system by influencing the fluid dynamics of the intake and / or exhaust systems.

STATE OF THE PRIOR ART

EGR valves that allow to implement the technique of controlled exhaust gas recirculation are already known.

Document US - 7,267,139 illustrates a Long Route EGR valve in which there are two throttle type adjustment elements. In particular, a first element, hereinafter referred to as butterfly 7a (see numbering in fig. 1 of the cited document), controls the flow of EGR gases, while a second element, hereinafter referred to as butterfly 7b, controls the flow of air in the engine intake. When small EGR flow rates are required, only the throttle 7a intervenes in the adjustment, while the throttle 7b is kept in the fully open configuration. Flow rates greater than EGR are obtained by suitably closing the throttle 7b and leaving the throttle 7a completely open. This creates a greater depression downstream of the butterfly 7a, capable of recalling through the latter greater flow rates of gas, proportional to the depression created. Therefore, the combination of closing the throttle element 7b (which creates a variation of the depression in the intake manifold) and the opening of the throttle 7a allows for variable EGR flow rates and to control even very small flow rates. The butterfly valves are operated by a single actuation system whose operation is of the electric type. The system is designed so that at least one of the two butterflies is always open and through the electric motor it is possible to adjust the two valves one at a time.

This solution obviously has the disadvantage of being excessively bulky and expensive; moreover, if on the one hand the butterfly valves have the advantage of a good permeability, on the other hand they do not allow to obtain good performances in terms of resistance to gas leakage in the working conditions in which - as mentioned above - do not you intend to activate EGR recirculation.

Document US - 6,880,572 proposes a much more compact EGR valve which offers a single inlet section and a single outlet section to the flue gas flow. This valve comprises a valve body in which a single movable element indicated with 16 is placed (in the numbering of fig. 1 of the cited document), which is connected to the shaft 18 of an actuation system. The exhaust gas flow enters the valve body through the inlet section, indicated with 12, passes through the internal duct of the valve body and exits through the outlet section indicated with 14.

During the closing maneuver, the shaft of the actuation system is rotated so as to make the coupling between the sealing surface present on the mobile element 16, which has an L-shaped configuration, and the surface of the seat placed in correspondence to the outlet section 14. When the valve is in the closed position the moving element closes the passage to the flow through the outlet port. Vice versa, during the opening maneuver, the actuating system shaft is rotated counterclockwise (with respect to the drawing in fig. 1 of the cited document) causing the valve to open. In the fully open position, the mobile element of the valve allows the exhaust gases to pass through the duct made in the valve body and then through the outlet section. In this configuration, the mobile element moves as far away as possible from the duct, within the limits of the foreseen movement range, resulting in the minimum encumbrance of the outflow area and maximizing the permeability of the valve and therefore the flow rate.

Conversely, when the actuator shaft is rotated so as to completely close the valve outlet section, the sealing surface of the moving element is coupled with the surface of the seat; in this way a good resistance to gas leakage is obtained, also thanks to the force exerted by the flow against the surface of the mobile element facing the duct.

As regards the operating modes, it should be noted that the EGR valve according to US-6.880.572 is equipped with a safety drive in case of failure of the actuation device. In fact, in the event of a malfunction of the actuation system, the valve remains closed, since the moving element is stressed by the fluid so as to assume the configuration corresponding to the complete closure of the valve. This occurs even if the malfunction occurs when the valve is completely open, as the fluid exerts a thrust against the moving element, to the point of causing it to rotate and return the valve to the closed condition. The solution described has evident limits to the reliability of the safety actuation, as it is substantially operated by the thrust of the fluid alone.

A still different arrangement is discussed in the document US - 2008/0029073, in which an EGR valve is proposed which, as in the case just described, offers an inlet section and an outlet section to the flue gas flow. This valve comprises a valve body, in which a single movable element 20 is located (in the numbering of Fig. 1 of the cited document), which is connected to the shaft 18 of an actuation system. The actuation system is based on the use of an electrical device, and also provides for the use of a gear transmission. Also according to this solution, the EGR gas flow enters the valve body through an inlet section, passes through the internal duct of the valve body and exits through an outlet section. Furthermore, the configuration of the valve requires the use of a torsional spring capable of exerting a suitable torque during the valve actuation dynamics.

In the fully open configuration, the mobile element of the valve has a minimal influence on the EGR gas flow rate; this is due to the fact that, in correspondence with the completely open valve configuration, it is located inside a compartment provided in the valve body. In this way the EGR valve is characterized by a high permeability to the flow of EGR gases.

The valve is also characterized by a good resistance to gas leakage due to the presence of a flexible and at the same time resilient connection between the mobile element and the disk arranged on it. This connection means that, in the final part of the closing maneuver, the disc moves in a direction that is almost parallel to that of the EGR flow with resulting accurate positioning of the disc on its respective seat.

This valve is proposed for low pressure applications of the controlled flue gas recirculation technique. For these reasons, the document US - 2008/0029073 is considered here as a known art closest to the present invention.

PROBLEM AND SOLUTION

The present invention has the objectives of guaranteeing high performance in terms of tightness, that is, resistance to gas leakage, when the valve is brought to assume the closed configuration; to offer an accurate regulation of the recirculation gas flow rate; to be able to process high gas flow rates when the valve is brought to assume the opening configuration. Unlike US-2008/0029073, the proposed invention has three distinct outflow zones and, being able to influence the conditions of the flow field on the intake or exhaust side, it achieves better characteristics of permeability to the gas flow.

In particular, a first problem consists in providing an EGR valve for low pressure applications of the controlled exhaust gas recirculation technique, which possesses the functional characteristics of high permeability to the recirculation gas flow, of high resistance to leakage, of accurate regulation. of the EGR flow rate and, in addition, to allow the partialization of the air inlet to the engine, grouped in a single construction unit.

A second problem consists in providing a system which, in addition to the aforementioned functional characteristics of high permeability, high resistance to leakage, accurate regulation of the EGR flow rate, allows the partialization of the gas flow out of the engine exhaust system without thereby imply onerous complications of the constructive solution of the system itself, these characteristics still being grouped in a single constructive unit.

Since the configuration of the mobile element of the EGR valve according to the document US-2008/0029073 is not, however, such as to allow an accurate resolution of the EGR flow rate adjustment, a further aim of the present invention is to propose a device which, in addition to possessing the aforementioned characteristics of high permeability, high resistance to leakage, allowing the partialization of the motion field on the intake or exhaust side, allows, more specifically, an accurate regulation of the EGR flow rate with simpler and better controllable means , and using a single actuator.

In particular, a further problem consists in providing a system in which the aforementioned operating functions are achieved by providing in the embodiment of the EGR valve a single movable element operated by a single actuator; this movable element, therefore, performs both functions: that of a regulating element and that of a sealing element.

These objects are achieved through the characteristics mentioned in the independent claims 1 and 16. The subordinate claims describe preferential characteristics of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The main constructive and functional technical characteristics of the present invention and the advantages deriving from them are however more evident from the following description of preferred embodiments of the invention; given purely by way of non-limiting example and illustrated in the attached drawings, in which:

Fig. 1 is an isometric view of the EGR valve according to a preferred embodiment as a â € œthree-wayâ € valve;

Fig. 2a is a sectional view of the same EGR valve as fig. 1, with movable element in intermediate working position; this figure also provides an indication of the flows when the valve is applied to the suction side;

Fig. 2b is a sectional view completely identical to that of fig. 2a, except that said mobile element is in the completely closed position;

Fig. 2c is a sectional view completely identical to that of fig. 2a, except that said mobile element is in the fully open position, until the flow in the main duct of the valve body is reduced; this figure also provides an indication of the flows when the valve operates the partialization of the intake air flow;

Fig. 2d is a sectional view completely identical to that of fig. 2c, unless said valve is applied to the exhaust; this figure also provides an indication of the flows when the valve operates the partialization of the exhaust gas flow;

Fig. 3 is a sectional view of the moving element of the EGR valve; Fig. 4 is a perspective view of the same moving element of the EGR valve;

Fig. 5 is an application diagram of the EGR valve in an internal combustion engine, in an arrangement that provides for the partialization of the intake air flow;

Fig. 6 is an application diagram of the EGR valve in an internal combustion engine, in an arrangement that provides for the partialization of the exhaust gas flow;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown first of all in Figures 2a, 2b and 2c and 5, the Long Route EGR valve proposed by the present invention is described as a valve inserted on the intake of the internal combustion engine MCI. It looks like a valve of the `` three-way '' type, in whose body 1 a duct 1a is formed, hereinafter conventionally called main duct 1a, at the ends of which there are two outflow sections, i.e. an outflow section 2, which acts as the inlet section of the fresh charge in intake to the engine, and an outflow section 3 which acts as the outlet section of the mix of air and cooled EGR, and a duct 1b, hereinafter conventionally indicated secondary duct 1b, which from one side is inserted into the main duct 1a and on the other side it ends in an outflow section 4, which acts as the inlet section of the cooled EGR gas.

More precisely, the duct 1a is formed in a first part of the body 1, of tubular geometry, while the duct 1b is formed in a second part of the body 1, which ends with an outflow section 4, in the terminal area 4a, in which a ring 6 forming a valve seat is also arranged.

In the passage from the first part to the second part of the body 1, an interface zone 9 is formed with a corresponding outflow section 9a. In this outflow section 9a, between the main duct 1a and the secondary duct 1b, the mobile valve element 5 is located, preferably constrained to the second part of the body 1; the configuration and arrangement of this element 5 are better described below.

In the embodiment illustrated in the drawings, said secondary duct is connected to said main duct preferably, although not necessarily, at an acute angle. The constraint of said mobile element 5 is then positioned inside said acute angle.

The valve body 1 can be formed as a single body or, as shown schematically in fig. 1, by two distinct bodies - the first part, with the duct 1a, and the second part, with the duct 1b - connected together by conventional clamping screws 8, which allow the coupling of a certain number of suitably sized and opposite flaps. The coupling of the valve body 1 to the engine system, that is to the intake and exhaust systems, takes place in an equally conventional way by means of flange surfaces in zones 7 and 4a (see fig. 1), respectively on the first part and on the second part of the body 1, and by means of conventional clamping screws.

As shown in greater detail in the sectional view of fig. 3 and in the perspective view of fig. 4, the mobile element 5 consists of two main elements 12 and 13.

The element 12 - which, due to its geometric conformation, envisaged in this embodiment of the present invention, is briefly defined below as a vane element or, more simply, as a vane 12 - is coupled rigidly to a shaft 11 which, in turn, is constrained to the second part of the valve body 1, so as to possess only the degree of freedom relative to rotation around an axis orthogonal to the plane of fig. 3, and whose trace in the same plane is indicated with X .; this coupling is achieved by means of common clamping screws 18 (visible in the drawing of fig. 4).

As already said, and as can be clearly seen from fig. 2a, the hinge X axis is positioned in correspondence with the outflow area 9, inside said acute angle formed between the axes of the main and secondary ducts.

The element 13 is coupled to the blade 12, in the form of a disc. This disc 13 is entrusted with the sealing function on the valve seat 6, while the vane 12 is entrusted above all with the function of regulating the EGR flow.

According to a fundamental characteristic of the present invention, said coupling between the blade 12 and the disc 13 is achieved by means of a connecting pin 14, clearly visible in fig. 3. This coupling takes on specific functional characteristics thanks, on the one hand, to the particular geometric configuration of both coupled elements, that is to say the disc 13 and the blade 12 and, on the other hand, thanks to the presence of a single elastic element 15, as better specified below.

In this regard, it can be observed, in fact, that the blade 12 has a conical surface 12b, which offers itself in contact with a spherical surface 13b, formed on the disc 13 in the area of interface with the blade itself. Overall, the coupling that is established between the vane 12 and the disc 13 possesses the functional characteristics of a ball joint, which are advantageous in terms of intrinsic capacity for fine adjustment of the position of the disc 13, as explained below.

Furthermore, the single elastic element 15, which holds the disk 13 and the blade 12 coupled, consists of a single cup spring, interposed between the end 14a of the pin 14 and the surface 12a of the blade; on the side opposite the head 14a, the pin 14 has a stop edge 14b, which rests inside a housing 13c of the disc 13.

A further expedient adopted in the constructive solution of the mobile element of the EGR valve proposed by the present invention consists in the arrangement of a fixing element 16, which binds the disc 13 to the vane 12 so as to cancel the degree of rotational freedom of the relative motion of the disc 13 with respect to the blade 12 itself. In this way the rotation of the disc 13 around its own axis is prevented, which could be generated during the opening / closing maneuvers of the valve, which involve the rotation of the blade around the X axis. relative motion of the disc 13 with respect to the vane 12, consisting in a rotation of the disc around the axis of the pin 14, could have a negative influence on the motion field of the EGR flow, and could also lead to undesirable phenomena of local development of heat, due to the friction that would occur in this relative motion.

A torsional return spring (suitably sized, but not shown) is fixed with one end to the shaft 11 and with the other end to the body 1 (or possibly directly to the body 17 of the movement system which controls the rotation of the € ™ post 11); this fixing is not shown in detail as it is known per se and in any case within the reach of a person skilled in the art. Said torsional spring is mounted in such a way as to act on the mobile element 5 in the direction of pushing it towards its closure against the seat 6.

A further feature of the constructive solution of the Long Route EGR valve proposed by the present invention consists in the provision of a cooling circuit in the valve body, in correspondence with the outflow section 4, for the inlet of the recirculation gas. This cooling circuit is concretely constituted by an inlet duct 10, by a duct 10a, obtained inside the valve body, in the area surrounding the valve seat 6 (visible in Figures 2), and by an outlet duct ( not shown in the drawings). The function performed by this cooling circuit is to reduce the thermal stresses deriving from the presence of temperature gradients caused by the flow of recirculating gases.

The operation of the valve described above - and mounted on the intake, as mentioned above - requires that the flow of air directed to the engine intake passes through the inlet section 2, flows into the main duct 1a of the body of valve and mix with the recirculation gas flow entering from the outflow section 4 and flowing through the interface section 9. The mixture of the two flow rates, that of intake air and that of recirculating gas, comes out from the main duct of the valve through outlet section 3.

The constructive solution of the Long Route EGR valve according to the invention therefore presents â € œthree distinct fluid waysâ €, that is, three passage sections affected by fluid flow rates that are different not only for the characteristics of the flow range, but also for composition: the outflow section 2 for the inlet of the intake air flow; the outflow section 4 for the inlet of the recirculation gas flow; and finally the outflow section 3 for the outlet of the flow rate resulting from the mixing of the previous two.

The EGR flow rate must be suitably adjusted in accordance with a precise management logic of the MCI engine, and is therefore variable according to the operating conditions of the engine itself.

In addition, as already said, when the EGR valve is brought to assume the closed configuration (fig. 2b) it is necessary to maintain a high resistance to the leakage of the recirculating gases, despite the difference in pressure existing between upstream and downstream. of the outflow section 4 of the recirculated gas.

All the functions described, i.e. that of regulating the EGR flow rate at the inlet from the outflow section 4 into the secondary duct 1b and / or that of regulating the flow of fresh air into the main duct 1a, as well as that of sealing the seat 6 of the valve due to the perfect adhesion of the disc 13 on the seat 6, are carried out by the aforementioned single movable element 5 of the valve.

More precisely, the flow rate adjustment function is concretely carried out by the vane, which carries out a progressive partialization of the EGR flow rate entering the valve from the outflow section 4. The degree of partialization of the EGR flow rate depends on the angular position assumed by the vane, around the X axis, within the range of angular rotation that characterizes the law of movement.

This law of movement, as already mentioned, is implemented by a movement system known per se, which is based on an electrical device, such as a direct current electric motor, and which can use a transmission with one or more reduction stages. In the context of the present invention, the movement system of the mobile element of the Long Route EGR valve is to be understood as known per se and therefore is represented only through the body 17 (fig. 1) which contains all the constituent elements; the latter is rigidly coupled to the valve body.

In greater detail, the operation of the valve according to the present invention and the advantages deriving from it - when the valve is mounted on the suction side of the MCI motor - are better evident from the following description of the valve closing operation (fig. 2b), starting from a generic configuration of open valve (fig. 2a), and the complete opening of the valve (fig. 2c), up to the partialization of the air inlet to the MCI.

When, starting from a generic configuration of open valve (as in fig. 2a or 2c), the closing maneuver is carried out, then the vane 12 is made to perform a clockwise rotation (with respect to the drawing) around the X axis , moving against the direction of the EGR flow coming from the outflow section 4 of the secondary duct 1b. It is observed that at the beginning of the closing maneuver the surface 13a of the disc 13 moves according to a trajectory which is not parallel, but oblique, with respect to the direction of the EGR flow; this trajectory then becomes almost parallel to the flow direction only in the final section of the closing stroke. The closing maneuver is defined in such a way that, upon completion of this maneuver, the surface 13a of the disc 13 abuts against the flat surface of the circumferential edge of the element 6; this element, which acts as a valve seat, is located on the secondary pipe 1b of the valve body, in correspondence with the recirculation gas outlet section 4.

At this point we understand the advantages deriving from the functional characteristics of the ball joint that distinguish the coupling that has been established between the blade 12 and the disc 13. As previously stated, these advantages are measured in terms of a intrinsic ability to fine-tune the position of the disc 13 with respect to the abutment surface of the valve seat 6; in particular the disc 13, and therefore the surface 13a, moves towards the abutment surface according to a trajectory which, in the last section of the valve closing stroke, is almost parallel to the EGR flow. Furthermore, when the disc 13 rests on the valve seat 6, it is possible to freely settle the disc 13 in a position of perfect coupling with the valve seat 6.

When, starting from the closed valve configuration, the valve is fully opened, then the vane 12 is made to rotate counterclockwise around the X axis, this time moving in the same direction of the flow. of EGR coming from the outflow section 4. Furthermore, in the first section of the opening maneuver, in correspondence with which the surface 13a of the disc 13 and the surface of the seat 6 move away, the surface 13a moves according to a trajectory which is almost parallel to the direction of the recirculation gas flow.

In the opening movement from the closed position (fig. 2b) to a generic intermediate position (fig. 2a), the vane 12 performs the partialization of the EGR flow introduced - in greater or lesser quantities - into the flow of air inlet to the MCI which runs through the main duct 1a, from inlet 2 to outlet 3.

However, by continuing the anticlockwise rotation of the mobile element 5 of the valve, beyond the intermediate position of fig. 2a and up to the overcoming of the interface section between the flows 9, the vane 12 also performs the partialization of the flow of air inlet to the engine. The partialization of the intake air increases the performance of the system in terms of permeability to the recirculation gas flow. Upon reaching the valve's complete opening configuration (fig.2c), which corresponds to the maximum angular excursion foreseen by the blade movement law, the maximum partialization of the inlet air flow from section 2 of the main duct 1a of the valve is obtained. The air flow is in fact intercepted by the surface 12a of the blade 12; this surface therefore operates the partialization of the flow rate of air inlet to the MCI engine.

In order to better understand the operating dynamics of the EGR valve proposed by the present invention, it is observed that during the closing maneuver the movement system is required to ensure the shaft 11 axis, to which it is connected the vane 12, the torque which is necessary to overcome the fluid dynamic resistances and complete the maneuver within the desired time of actuation. During this closing maneuver, the elastic torque of the spring works in accordance with the torque developed by the movement system.

On the other hand, during the opening maneuver, the movement system is called upon to guarantee to the axis of the shaft 11, to which the blade 12 is connected, the necessary torque to overcome the elastic torque of the spring and complete the maneuver. in compliance with the predefined implementation times. During the opening maneuver, the elastic torque of the spring in fact works in opposition to the torque developed by the movement system, and to that deriving from the thrust of the recirculation gas flow.

The accuracy of the flue gas flow control can be varied according to the type of application, by modifying the configuration of the mobile element of the valve, of the main and secondary ducts, and of the respective outflow sections. The alteration of one or more of these components affects the actual profile of the outflow area. The resolution of the flow control is the ratio at which the effective outflow area changes as the moving element moves towards the valve seat; this relationship can be controlled and predetermined. The profile of the outflow area can be modified so that with the progression of the movement there is, due to the permeability of the valve, a relatively slow growth, or a proportional increase, or even a relatively rapid growth.

To define the configuration of the outflow area profile, it is possible to proceed through an experimental type approach (laboratory flushing tests), but preferably the optimization of the outflow area involves the widespread use of CFD analyzes during the design phase and subsequently the experimental verification, as is known in the art.

Still with regard to the operating dynamics of the EGR valve discussed in the present invention, it can be observed that where a malfunction of the movement system occurs during normal operation of the valve, it is still possible to guarantee a closing operation of the valve itself at suitable times. This safety operation is guaranteed by the presence of the torsional spring acting on the shaft 11 and therefore by the elastic return torque exerted by it, which tends to bring the blade 12 back to the closed position, i.e. the surface 13a of the disc 13 in abutment. against the seat surface 6.

In addition to making the safety operation described above possible, under normal operating conditions, the elastic torque of the spring contributes to the high performance of the EGR valve in terms of resistance to the leakage of recirculating gases, when the valve is in the configuration of closure.

The description of the embodiment of the invention discussed up to now provides for an application in relation to a recirculation system of the type schematically shown in fig. 5. It is noted here that the EGR valve, as illustrated in FIG. 1, is arranged upstream of the compressor C, and makes it possible to choke the LPE flow of EGR cooled by the cooler CO, and / or the air inlet to the engine. The recirculation system considered is the conventional one of a supercharged diesel internal combustion engine equipped with exhaust gas treatment devices such as a CAT catalyst and a DPF particulate filter. The other elements present in the diagram are a common AF air filter, an AFM mass flow meter, a T turbine, an IC intercooler, and an MCI engine block, to which the IM intake manifold and the EM exhaust manifold are connected.

The preferred embodiment of the present invention as the Long Route EGR valve â € œthree-wayâ € - as described above with reference to the attached figures - may however be susceptible of further application without requiring substantial modifications of the constructive solution so far described. More precisely, the only variation consists in the different arrangement of the Long Route “three way” valve in the EGR recirculation system in the MCI, ie on the exhaust side rather than the intake side of the MCI engine.

This application consists in arranging the EGR valve in a recirculation scheme as shown in fig. 6, in which the MCI motor is of the same type as that shown in fig. 5, while the function performed by the three outflow sections of the valve is different, since the operating conditions of the valve are different.

This different arrangement of the valve, in relation to the internal combustion engine MCI, allows to carry out a new application of the technique of controlled exhaust gas recirculation in an MCI and therefore defines an additional Long Route EGR system, which is still innovative in terms of operational and performance characteristics.

Through this different arrangement it is possible, again within the scope of the present invention, to propose a valve which, in addition to the functional characteristics of high permeability and high resistance to leakage, can also allow the partialization of the gas flow at the outlet from the discharge of the MCI, without thereby implying onerous complications of the constructive solution of the system itself.

In order to better understand this different arrangement of the invention, a brief description of how the valve should operate is provided below with reference to fig. 6, and keeping the reference to the same drawings of the attached figures and additionally to fig. 2d, as regards the structure of the valve (of which, therefore, the constructive characteristics are not repeated, as they are unchanged with respect to the embodiment discussed above).

The `` three-way '' Long Route EGR valve can be thought of as applied with the outflow section 3 of the main duct 1a as the exhaust gas inlet section (indication EG-IN in fig. 2d), with the exhaust section outflow 4 of the secondary duct 1b as the EGR outlet section (EGR indication in fig. 2d) towards the mixing with combustion air, and therefore towards the engine supply, and finally with the outflow section 2 of the main duct 1a which outlet section (EG-OUT indication in fig. 2d) of the flue gas flow not involved in the recirculation. When, starting from the closed valve configuration, the valve opening maneuver is carried out, then the vane 12 is again brought to perform a counterclockwise rotation, around the X axis, and therefore the movement system is called to guarantee to the axis of the shaft 11, to which the blade 12 is connected, the necessary torque to overcome the elastic torque of the spring and to complete the maneuver in compliance with the predefined actuation times.

In a generic open valve configuration, the flow of flue gases entering the outflow section 3 of the main duct 1a of the valve is reduced by the mobile element 5 so that only a metered portion of this flow rate is directed towards the outflow section 4 of the secondary duct 1b of the valve, while the remaining part of the exhaust gas exits from the outflow section 2.

The flue gas flow directed towards the outflow section 4 constitutes the EGR flow rate to be redirected to the MCI intake. The greater the amplitude of the counterclockwise rotation - until the valve is fully opened (fig. 2d), corresponding to the maximum angular excursion foreseen by the law of movement of the mobile element 5 - as much the greater the flow of flue gases conveyed to the MCI supply. The remaining part of the exhaust gas is instead let out and discharged to the outside through section 2 of the main duct 1b. By continuing to open the valve beyond the interface section 9, the flow of exhaust gas that passes through the main duct 1a is reduced; this entails an improvement in the performance of the valve in terms of permeability to the flow of the exhaust gases to be recirculated, due to an increase in pressure in the area of the main duct 1a upstream of the valve. When the valve is fully opened (fig. 2d), corresponding to the maximum angular excursion foreseen by the movement law of the mobile element 5, the maximum partialization of the exhaust gas flow through the main duct 1a is obtained. The fundamental characteristic of this further embodiment therefore consists in the fact that the EGR Long Route valve `` three ways '' processes only the flow deriving from the MCI exhaust system, while the number of outflow sections that characterize the valve itself.

The operation of the EGR valve is defined by a precise control logic which, by means of an appropriate circuitry, processes the signals coming from the sensors present on the device and in particular from a sensor dedicated to detecting the position assumed by the mobile element of the valve. and, according to the type of predefined control strategy, it activates the movement system of the mobile element of the valve in order to implement the appropriate movement law. The description of the control logic and of the type of circuitry and sensors that make it feasible goes beyond the context of the present invention.

However, it is understood that the invention should not be considered limited to the particular provisions illustrated above, which are only exemplary embodiments of it, but that various variants are possible, all within the reach of a person skilled in the art, without thereby departing from the scope of protection of the invention itself, as defined by the following claims.

LIST OF REFERENCE CHARACTERS

1) valve body

1a) main duct

1b) secondary duct

2) outflow section

3) outflow section

4) outflow section

4a) flanged area

5) movable element of the valve

6) valve seat

7) connection flange

8) clamping element

9) interface section

9a) outflow area

10) inlet of the cooling circuit 10a) duct of the cooling circuit 11) shaft

12) headstock

12a) surface of the vane

12b) blade-disc coupling surface 13) disc

13a) disc sealing surface

13b) disc-blade coupling surface 14) disc-blade connection element 15) elastic element

16) blade-disc constraint element

17) handling device body 18) blade-shaft tightening screws

Claims (1)

CLAIMS 1) Valve assembly for low pressure applications of controlled exhaust gas recirculation of an internal combustion engine (ICE), the body of which includes a flow duct with at least one inlet and one outlet section, as well as at least a mobile element acting as a valve, cooperating with a valve seat, said mobile element being constituted by the coupling of a bearing element and a sealing element, the bearing element being in the form of a rotating arm around an axis perpendicular to the direction of the gas flow, and the sealing element being in the form of a valve seat sealing disc, characterized by this that said valve body comprises a main duct (1a), with a first outflow section (2) at one of its ends, and a second outflow section (3) at the other end, and a secondary duct (1b) , which has a third outflow section (4), at one of its ends, and which, at the other end, is connected to said main duct through an interface section (9a); And that said single mobile element constitutes as a whole an element for sealing a valve seat, located in correspondence with said third outflow section and, at the same time, a means for choking the flow rate of the flows in said secondary duct and / or in said main duct, 2) EGR valve assembly as in claim 1, characterized by what said main duct (1a) is formed in a first part of the body 1, of tubular geometry, while said secondary duct (1b) is formed in a second part of the body 1, said first part and said second part of the body being made as a unitary element. 3) EGR valve assembly as in claim 1, characterized by what said main duct (1a) is formed in a first part of the body 1, of tubular geometry, while said secondary duct (1b) is formed in a second part of the body 1, said main part and said secondary part being made as two distinct elements, coupled by means of clamping systems, to constitute the whole of the EGR valve body. 4) EGR valve assembly as in claim 1, characterized by what said secondary duct is connected to said main duct under an acute angle, the hinge of said mobile element being positioned inside said acute angle, preferably in proximity to said interface section (9). 5) EGR valve assembly as in claim 1, characterized by what said movable element is in the form of a composite element with vane and disc, called vane element, assuming the function of a flow regulating element and said disc element having essentially function of sealing the valve seat. 6) EGR valve assembly as in claims 1 or 5, characterized by a ball joint coupling between said blade and said disc, which allows intrinsic self-regulation properties of the relative position of the disc with respect to the blade and with respect to the valve. 7) EGR valve assembly as in point 6, characterized by this said coupling with a ball joint, between the blade and the disc, is made by means of a connecting pin (14), which passes through a central hole of both the blade (12) and the disc (13), as well as by a single elastic element (15), which holds the disc against the blade. 8) EGR valve assembly as in claim 7, characterized by what the vane (12) has, in correspondence with its central hole, a conical surface (12b), which is offered in contact with an opposing spherical surface (13b), formed as a rim protruding from the surface of the disc (13), in the interface area with the blade (12) itself, conical surface (12b) and spherical surface (13) forming said spherical joint. 9) EGR valve assembly as in 7, characterized by the so-called elastic element (15), which holds the disc (13) and vane (12) coupled, is made in the form of a single cup spring (15 interposed between a head enlarged (14a), formed at the upper end of the pin (14), and the surface (12a) of the vane (12). 10) EGR valve assembly as in any one of claims 7 to 9, characterized in that said connecting pin (14) has, on the side opposite the head (14a), a stop rim (14b), which rests on the € ™ interior of a recessed housing (13c), formed in the lower surface (13a) of the disc (13). 11) EGR valve assembly as in any one of claims 7 to 10, characterized in that a stop pin (16) is fixed on the vane (12) and projects into an opposite cavity of the disc (13), with the function of constraint of the disc (13) against rotation around the axis of the pin (14). 12) EGR valve assembly as in any one of the preceding claims, characterized in that said vane is mounted integral with a shaft (11), which is rotatable on an axis positioned inside said second part of the valve body (1). 13) EGR valve assembly as in 12, characterized by what is also mounted on said shaft (11) a torsional return spring, fixed with one end to said shaft (11) and with the other end on said second part of the valve body (1), in such a way that its action is carried out in accordance with the torque generated by said motor means on said shaft when closing the valve seat, in order to improve the closure against leakage and to carry out closing safety function in the event of failure of said motor means. 14) EGR valve assembly as in any one of the preceding claims, characterized in that said valve seat is constituted by the flat surface of the circumferential edge of an annular element (6), which is made as a inserted piece, housed in correspondence of said third outflow section (4). 15) EGR valve assembly as in any one of the preceding claims, characterized in that it comprises a cooling circuit of the valve body, made in correspondence with said third outflow section (4), on said second part of the body (1) of valve. 16) Exhaust gas recirculation system in an internal combustion engine equipped with means for low pressure control and regulation of the exhaust gas recirculation of an (EGR Long Route), characterized by what said means consist of a valve assembly as in any one of the preceding claims. 17) Exhaust gas recirculation system as in point 16, characterized by what said valve assembly is mounted on the engine from the intake side, called the first outflow section (2) constituting the inlet section for the intake air to the engine (MCI), said third outflow section (4) constituting inlet section for the recirculation gas, and said second outflow section (3) constituting outlet section for a mixture of air and recirculating gas. 18) Exhaust gas recirculation system as in claim 17, characterized by what said movable element with blade and disc is movable starting from a sealing position on said valve seat (6), in which it is prevented any recirculation of exhaust gases, progressively towards at least an intermediate position in which it allows at least a partial recirculation of the exhaust gases, without directly interfering with the flow of intake air, and up to a position of maximum opening, in which the maximum Interference with the air flow entering the main duct and therefore the maximum partialization of this air flow occurs. 19) Exhaust gas recirculation system as in claim 16, characterized by what said valve assembly is mounted on the engine on the exhaust side, said second outlet section (3) constituting the inlet section for the combustion gases exiting the engine ( MCI), said third outflow section (4) constituting the outlet section of a controlled quantity of recirculation gas, and said first outflow section (2) constituting the outlet section for excess burnt gas. 20) Exhaust gas recirculation system as in claim 19, characterized in that said movable element with blade and disc is movable starting from a sealing position on said valve seat (6), in which it is prevented any recirculation of exhaust gas, progressively towards at least an intermediate position in which it allows at least a partial recirculation of the exhaust gases, without directly interfering with the flow of exhaust gas entering the main duct, and up to a position of maximum opening, in which there is maximum interference with the flow of exhaust gas in the main duct and therefore the maximum partialization of this flow of exhaust gas occurs.