ITBO20110749A1 - VALVE FOR INTERNAL COMBUSTION ENGINE - Google Patents

Description

Description

VALVE FOR INTERNAL COMBUSTION ENGINE

Technical field

The present invention relates to a valve suitable for use in an internal combustion engine.

Known art

It is known that internal combustion engines operating according to the well-known Otto or Diesel cycle or similar or derivative cycles usually employ interception means for controlling the supply and discharge of the combustion fluids for each cylinder of the engine. These interception means are usually of the type of so-called `` mushroom '' valves, suitable for controlling the flow of air and fuel, as well as the exhaust of the burnt gases through a respective passage opening provided for each cylinder, activating the Ÿ opening and closing in appropriate phase relation to the reciprocating motion of the piston inside the same cylinder.

Known mushroom valves can be operated by means of control elements, for example mechanical ones suitable for conveniently controlling the descent of the interception element inside the combustion chamber, therefore the opening, or on the contrary, the exit from the combustion chamber. combustion, then closing. These known solutions do not fully satisfy the needs of the specific sector. In fact, for example, the actuation of the poppet valves generates considerable inertia actions, which limit the power generated by the engine and therefore the overall efficiency of the system. In fact, the very conformation of the poppet valves requires considerable displacements of the valve body to determine a passage opening sufficient for the instantaneous flow rate required. Furthermore, the use of this type of valve is associated with the formation of fluid recirculation areas near the stem and therefore with high fluid dynamic losses.

Among the numerous problems of this known solution, it is necessary to mention at least the fact that in the event of the breakage of any part of the valve control unit, for example of a belt transmitting the motion from the crankshaft to the camshaft, there is no way to avoid the impact between the piston and the valve body which in any case is inside the combustion chamber, with consequent foreseeable damage to the respective mechanical parts. Furthermore, at the high rotation speeds of the engine, the use of these valves inevitably involves the problem of the so-called â € œflutteringâ €, associated with a not always correct closure of the combustion chamber. To reduce the effects of this phenomenon, it is in fact necessary to appropriately reduce the maximum engine speed and therefore the power that can be obtained.

Furthermore, it is important to note that in the known solutions, the interception members used have considerable drawbacks with regard to the wear of the parts in relative movement.

In fact, in the step of closing known valves, continuous sliding occurs between the surfaces involved, therefore undesirable phenomena arise, such as vibrations and noises, exposing the mechanical parts involved to considerable dynamic and thermal loads. In fact, it must be borne in mind in this regard that the lower portion of each poppet valve, the so-called â € œpanelâ €, is exposed continuously as well as directly to the high temperatures of the combustion chamber. Presentation of the invention

The task of the present invention is that of solving the aforementioned problems, devising a valve suitable for use in an internal combustion engine which allows to provide optimal performance in terms of wear resistance and sealing capacity.

Within this aim, a further object of the present invention is to provide a valve capable of optimally controlling the outflow and discharge of a fluid.

Another object of the invention is to provide a valve with a simple constructive and functional conception, with reliable operation and versatile use.

The aforementioned purposes are achieved, according to the present invention, by the valve for an internal combustion engine according to claim 1.

These objects are achieved essentially thanks to the inventive idea of using a valve provided with an obturator member having at least one operating surface arranged converging according to the closing direction of the valve. This solution ensures effective closing, as well as instantaneous opening of the valve, in any use. In particular, the proposed solution minimizes the extension of the surfaces subject to sliding and therefore to wear, guaranteeing greater strength. Furthermore, the consequent reduction in friction optimizes yields and limits the development of heat where it is undesirable.

The embodiment according to which the said shutter member has the shape of a wedge and has a substantially trapezoidal section according to a median longitudinal plane is particularly advantageous. This solution is designed to ensure particularly effective and safe operation of the valve.

Finally, the valve can include a through hole, transversal to the opening and closing direction of the valve, designed to allow the passage of a fluid to be intercepted. This solution allows to reduce the opening and closing stroke of the valve.

According to a particular embodiment, the valve according to the invention can have at least one recess arranged on an operative face. This excavation is designed to accommodate any carbon deposits, reducing encrustations in other operational areas.

Brief description of the drawings

The details of the invention will become more evident from the detailed description of preferred embodiments of the valve for internal combustion engine according to the invention, illustrated by way of example in the accompanying drawings, in which:

Figure 1 shows a schematic perspective sectional view of a combustion engine adapted to use the valve according to the invention, also represented schematically,

Figure 2 shows a perspective view of the valve in question;

Figure 3 shows a perspective view of a detail of the combustion engine illustrated in Figure 1 adapted to use the valve according to the invention illustrated in Figure 2;

Figure 4 shows a perspective view of the same detail of the internal combustion engine illustrated in Figure 1 in which the valve in question is inserted; figure 5 shows a perspective sectional view of a different portion of the aforesaid engine, bearing the valve according to the invention;

Figures 6 to 10 respectively show a perspective view of further embodiments of the valve according to the invention.

Embodiments of the invention

With particular reference to these figures, the internal combustion engine adapted to use the valve according to the invention has been indicated as a whole with 1. The motor 1 comprises a casing 2 substantially conforming a first portion and a second portion. More precisely, the first portion of the casing 2 comprises a cylinder 3 containing in a known way an axially sliding piston, a crankshaft for transforming the reciprocating motion of the piston into rotary motion and a connecting rod connected to the piston and to the shaft elbows, for simplicity not shown in the figures (see in figure 1 a portion of the casing 2).

The aforementioned second covering portion of the casing 2 forms a head 4 preferably composed of a plurality of layers. For example, the head can have a first lower layer 4a forming the cover of the cylinder 3, a second upper layer 4b, for closing the head 4, and possibly one or more intermediate layers 4c adapted to cooperate with the second layer 4b to house the members furniture inside the head 4, as better described below.

The multilayer head 4 also has passage ports 5 for the intake and discharge of a fluid, a combustible mixture, through a combustion chamber 6 of variable volume, as it is defined between the top or crown of the mobile piston and the lower portion of the head 4 itself.

For example, the head 4 can provide an intake port 5a for the outflow of the combustible mixture from the respective intake ducts to the combustion chamber 6 and an exhaust port 5b for the outflow of the burnt gases from the combustion chamber 6. Alternatively, it can be provided for a greater number of intake and / or exhaust ports 5 in communication with the same combustion chamber 6.

The ports 5 can have any section as long as it is suitable for the passage of the required flow rate of fuel mixture and, respectively, of burnt gas, for example rectangular, but also polygonal, rounded, circular and the like.

Positioned in the head 4 are the interception valves 10 adapted to intercept respectively the intake port 5a and the exhaust port 5b, as well as a respective control unit 11 to actuate the valves 10 in a suitable phase relationship to the reciprocating motion of the piston at the € Ÿ inside the cylinder 3, according to the known operating cycle of reciprocating internal combustion engines. The control unit 11 illustrated is for example of the mechanical type and comprises a cam member 30 housed in a respective compartment 50 obtained inside the casing 2, in the head 4 and / or in the cylinder 3. Alternatively, the control 11 for actuating the valves can also be partially electronic, for example for controlling a single valve or a single stroke of the respective reciprocating motion.

More precisely, the valves 10 are guillotine-shaped, capable of being operated by the respective control units 11 according to an alternating linear motion in the direction of the respective longitudinal axis, transversely to each port 5, so as to operate alternately opening and closing them ( see figure 1). In particular, the opening and closing operated by the valves on the plane of the ports 5 is advantageous as it optimizes the area made available for the passage of the suction or discharge fluids, with the same stroke performed by the interception devices. Furthermore, these members are minimally exposed to the combustion chamber, and in any case move away from the chamber itself in phases affected by considerable thermal and dynamic loads, such as that of exhausting the burnt gases.

More precisely, each valve 10 comprises an obturator member 12 of such conformation as to gradually obstruct the corresponding port 5a, 5b, a stem 13 inserted sliding axially inside a guide sleeve, a control portion or bowl 14 at the opposite end of the stem 13. In the embodiment illustrated in Figure 2, in particular, the valve 10 is also equipped with a collar 15 suitable for housing any return members 16, for example of the elastic spring type. In the case illustrated in Figure 4, in which the valves 10 release the ports 5 by means of a retraction stroke, in the opening motion the return members 16 are able to be compressed against a respective seat 20 shaped in the head 4, of shape conjugated to the respective valve, while in the closing motion the same members 16 are subject to expansion. Between the stem 13 and the obturator member 12 a shoulder 17 can be provided to seal the respective and opposite walls of the same seat 20, to avoid leaks of fuel mixture or burnt gases through the head, both in the opening and closing (see Figures 3, 4 and 5).

The shutter member 12 has at least one face 18 converging in the direction of the closing motion of the valve 10. In the case illustrated in Figure 2, the shutter member 12 is wedge-shaped, in particular with a trapezoidal section along a median longitudinal plane. In this case the closing motion of the valves 10 is forward and therefore the shutter member 12 has a trapezoidal section with the smaller base at the end, that is, at the tip.

The conformation of at least one converging face 18 of the shutter member 12 is particularly advantageous as it eliminates any sliding action on the face 18 itself with respect to the seat 20. As can be seen in figures 4 and 5 which illustrate the valve 10 which can be inserted between the first layer 4a and second layer 4b or an intermediate layer 4c, both in the opening position, backward, of the valve 10 and in the closing phase, advanced in the seat 20, the faces 18 of the obturator member 12 separate or vice versa couple instantly to the walls of the seat 20 without generating any friction in the intermediate stages of withdrawal or advancement.

Preferably, the shutter member 12 and the shoulder 17 have rounded, rounded or beveled edges. Alternatively, it is possible to equip the valve 100 with an obturator element 120 with several operating faces 180 with their respective sharp edges (see Figure 6).

According to a further embodiment, the valve 101, otherwise quite similar to that described above, comprises a wedge-shaped shutter member 121, equipped with a hole 19 for the passage of fluids. This solution allows to operate an opening stroke, according to a retraction motion of the valve 101, which is shorter than the solutions previously described. In fact, the presence of the passage hole 19 shortens the distance between the closed condition of the valve 101 and the condition in which the passage through the ports 5 is completely free to allow the outflow or outflow of fluids through the combustion chamber 6 ( see figure 7).

Finally, according to a further embodiment illustrated in Figure 8, it is possible to provide that the shutter member 122 of the valve 102 has an inverted wedge shape. This solution is used in the case in which the control unit 11 is operated to open the valves 102 according to a forward motion and to close them according to a retraction motion. As previously, in order to minimize the friction between the reciprocally sliding surfaces, the shutter member 122 comprises operating faces 182 converging in the closing direction, therefore in the retraction direction, of the valve 102. Furthermore, the solution provides for the realization of a shoulder 172 with sealing function, in a completely similar way to that described above. In fact, the shoulder 172 is able to abut a respective wall of the housing seat obtained in the head 4. It is also possible for this embodiment to apply a passage hole which is functionally similar to the hole 19 described for the solution illustrated in Figure 7.

Figure 9 instead illustrates an embodiment of the valve 103 in which the shutter member 123 has an excavation 21 on at least one respective operating face 183. This excavation 21 has in particular the function of concentrating any incrustations of carbon residues produced by the combustion of the gases which pass through the combustion chamber according to known cycles. Also for the embodiments described above, similar excavations can be provided on a single face of the shutter member or on several faces, to facilitate the localized concentration of the aforementioned encrustations.

By way of example, Figure 10 illustrates the valve 104 equipped with the hole 19 according to what is described for the valve 101 illustrated in Figure 7, in which the shutter member 124 further carries the excavation 21 on the operative face 184, to concentrate any carbon residues.

The operation of the internal combustion engine according to the invention can be deduced from what has been described above.

When the internal combustion engine 1 is started, the fuel is fed in a suitable mixing ratio with the air inside the combustion chamber defined between the piston crown and the portion of the lower head 4a facing the cylinder 3 .

The feeding of the fuel mixture, or of the air only depending on the case, is made possible by the activation of the control unit 11, mechanical or electronic, which controls the opening of the knife gate valve 10, 100, 101, 102 according to a direction longitudinal to the valve and transversal to the intake port 5a. In this phase, the piston completes the linear stroke from the top dead center to the bottom dead center.

In the next phase, the aforementioned valve 10, 100, 101, 102 closes the intake port 5a, allowing the piston, in the return stroke from the bottom dead center to the top dead center, to compress the gas present, for example the mixture fuel and air or air only for diesel engines. In particular, in the latter, the fuel is injected into the combustion chamber only when the piston is near the top dead center.

Subsequently, the combustion reaction takes place with the consequent generation of heat capable of determining the expansion of the burnt gases, pushing the piston towards the lower dead center.

Subsequently, the control unit 11 activates the valve 10, 100, 101, 102 corresponding to the exhaust port 5b, allowing communication with the exhaust duct, for the outflow of the burnt gases. At the same time the piston returns to the top dead center, that is to the initial phase of a new cycle of aspiration of the comburent mixture, as described.

The valve according to the invention, suitable for use in an internal combustion engine, therefore achieves the purpose of optimally controlling interception and sealing, minimizing the effects of sliding and wear. This result is obtained by using a shutter member 12, 120, 121, 122, 123, 124 having at least one operating face 18, 180, 181, 182, 183, 184 converging in the closing direction of the valves themselves. Basically, the operating face concerned closes and opens in a substantially instantaneous manner on a respective housing seat, ensuring complete detachment without sliding in the intermediate phases of approach and retraction with respect to the respective seat. Particularly effective is the embodiment in which the obturator organ is wedge-shaped, with a trapezoidal section.

Therefore, the valve according to the invention is of robust construction and reliable and long-lasting use even in the case of high dynamic loads.

A prerogative of the invention consists in the fact that the instant opening and closing operated by the valve minimizes the fluid dynamic losses in the open condition and at the same time accelerates the outflow or outflow of fluids in intermediate conditions up to opening. In fact, the wedge-shaped conformation of the guillotine valve operates an immediate detachment and therefore establishes a progressive but rapid opening of the passage opening 5, favoring an increase in the efficiency of the motor in which the valve is used.

In particular, in the case in which the opening motion occurs in the retraction direction of the valves, the ports 5 in the open condition are completely free for the passage of fluids, to the advantage of the compression ratio. The fed fluid can therefore flow or vice versa flow without obstacles that can create unwanted recirculation. Therefore the valve is perfectly permeable. The valve according to the invention is therefore very versatile and adaptable to the needs of the various sectors of use. It is also compact and light.

In the practical implementation of the invention, the materials used, as well as the shape and dimensions, can be any according to requirements.

Where the technical characteristics mentioned in each claim are followed by reference signs, these reference signs have been included for the sole purpose of increasing the understanding of the claims and consequently they have no limiting value on the purpose of each element identified by way of Ÿexample from such reference marks.

Claims (10)

Claims 1) Knife gate valve for an internal combustion engine comprising a shutter member (12, 120, 121, 122, 123, 124), a stem (13), a control portion (14) for actuation according to a motion alternative opening and closing, characterized by the fact that said shutter member (12, 120, 121, 122, 123, 124) has at least one operating face (18, 180. 181, 182, 183, 184) converging according to the direction of said closing motion of said valve (10, 100 , 101, 102, 103, 104). 2) Knife gate valve according to claim 1, characterized in that said shutter member (12, 120, 121, 122) has the shape of a wedge. 3) Knife gate valve according to claim 1 or 2, characterized in that said shutter member (12, 120, 121, 122, 123, 124) has a shoulder (17) oriented transversely to said stem (13) to ensure the tightness of said valve. 4) Knife gate valve according to claim 2 or 3, characterized in that said shutter member (12, 120, 121, 122, 123, 124) has a longitudinal median section with a substantially trapezoidal shape. 5) Knife gate valve according to claim 4, characterized in that said trapezoidal section has the smaller base facing the end of said valve (10, 100, 101). 6) Knife gate valve according to claim 3, characterized in that said trapezoidal section has the smaller base facing towards said stem (13). 7) Valve according to one of the preceding claims, characterized in that said shutter member (12) has rounded or beveled edges. 8) Valve according to one of the preceding claims characterized in that said shutter member has a passage hole (19) for a fluid to be intercepted, transversal to said closing direction of said valve. 9) Valve according to one of the preceding claims characterized by the fact that said shutter member has a recess (21) on a said operative face (183, 184) to concentrate any carbon deposits. 10) Knife gate valve according to one of the preceding claims in combination with an internal combustion engine of the type comprising a casing (2) forming at least one cylinder (3) containing an axially sliding piston, a crankshaft for the transformation of a reciprocating motion of said piston inside said cylinder (3) in a rotary motion of said shaft and a connecting rod member articulated to said piston and said crankshaft, a head (4) for covering said cylinder (3), a combustion chamber (6) defined internally between said head (4) and said piston axially sliding in said cylinder (3), passage ports (5a, 5b) communicating with said combustion chamber (6) for the intake and the discharge of a combustible mixture, at least one seat (20) obtained in said head (4) comprising a said passage opening (5a, 5b) for housing at least one said movable guillotine valve according to a reciprocating motion or opening and closing of said passage opening (5a, 5b), said seat (20) being conjugated to the convergent shape of said operative face (18, 180. 181, 182, 183, 184) of said valve (10, 100, 101, 102, 103, 104).