IT202100030122A1 - CONTROL SYSTEM OF A CYLINDER VALVE OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

DESCRIPTION

of the patent for industrial invention entitled:

?CONTROL SYSTEM OF A CYLINDER VALVE OF AN INTERNAL COMBUSTION ENGINE?

TECHNICAL FIELD

This invention? relating to a control system for a valve of a cylinder of an internal combustion engine.

The present invention finds its preferred application, although? non-exclusive, in the operation of one valve per cylinder of a ?split-cycle? type engine. Will this application be done? referenced below as an example.

STATE OF THE NOTED ART

The split-cycle engine, so-called ?split-cycle? ? returned to particular interest, thanks to its high efficiency which is greater than that of ?classical? internal combustion engines, that is? for example four-stroke engines; this greater efficiency reduces vehicle consumption and consequently polluting emissions.

How in itself? known, the split-cycle type engine separates the compression of the air and the combustion of the fuel mixture into two different cylinders.

In fact, while compression requires a higher temperature? possible low or greater dissipation of the thermal energy that develops from compression, combustion instead requires a higher temperature? higher or lower is possible, the greater dissipation of the thermal energy that develops from combustion.

Therefore, by separating compression from combustion, the split-cycle engine achieves greater efficiency than that of classic internal combustion engines.

However, the systems used to control the fluids passing through the cylinders of classic internal combustion engines are not easily usable in split-cycle engines. In particular, with particular reference to the intake valve, considerable problems arise.

As you know, the intake valve ? usually controlled by a control system that allows its movement within a respective seat to allow or deny the passage of air inside the cylinder.

The control system can be pneumatic or cam type.

In cam-type systems, a cam system controls the opening of the valve when pushed by the cam itself and a spring returns the valve to the closed position. Clearly, this recall needs to overcome a resisting force due to the pressure of the air entering the cylinder acting on the "mushroom" portion. of the valve, that is? the portion that cooperates in contact with the respective seat to close it.

This spring can be easily dimensioned in a standard system, since, considering the diameters of the valve heads of the valves on the market and the pressures involved which are of the order of 5 bar, the maximum return force that the spring must impart? less than 1000 N.

In split-cycle systems, the operating pressure is ? much greater as the air flows into the combustion cylinder already? compressed, therefore in values of approximately 100 bar. Therefore, without prejudice to the usually usable diameters, the return force that the spring would need to impart rises to values of a few thousand N, even greater than 5000 N.

Therefore, different solutions are possible to solve this problem.

It would be possible to decrease the diameter of the seat and mushroom by increasing the number of valves. Clearly this solution is cumbersome and expensive.

Furthermore, it would be possible to increase the strength of the springs by using different alloys or different sizes. This solution also greatly increases costs and dimensions since, due to the loads and the number of cycles involved, it would be necessary to produce springs of much larger dimensions than the current ones and in more durable materials. expensive.

In addition, both of the above solutions suffer from risks of inadvertent valve openings caused by dynamic problems. In fact, due to the high pressures involved, a standard type spring, when closing, would tend to rebound and oscillate.

In fact, given that to allow correct operation of the split-cycle engine? It is necessary to allow the passage of air in a narrow time interval close to the top dead center of the combustion cylinder, there would be impermissible air passages which would lower its efficiency.

As an alternative to the systems exposed above, ? It is possible to use pneumatic or hydraulic systems which, however, in order to overcome the forces involved due to the pressures involved in split-cycle type engines, require greater operating pressures and are therefore more expensive and consuming more? energy, thus reducing the overall efficiency of the engine system.

AND? therefore felt the need to provide a valve control system for an internal combustion engine cylinder that is precise, economical and takes up little space. In particular, ? felt this need in a split-cycle combustion engine cylinder.

Purpose of the present invention? satisfy the needs set out above in an optimized and economical way.

SUMMARY OF THE INVENTION

The aforementioned purpose? achieved by a control system and a motor as claimed in the attached claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred form of implementation is described below, by way of a non-limiting example and with reference to the attached drawings in which:

? Figure 1 ? a perspective view of a control system for an engine cylinder valve according to the invention;

? Figure 2 ? a side view of the control system of figure 1;

? Figure 3 ? a longitudinal sectional view of the control system of figure 2;

? Figure 4 ? a side view of the control system of figure 1;

? Figure 5 ? a perspective view of a control system for a pair of engine cylinder valves according to the invention;

? Figure 6 ? a longitudinal sectional view of the control system of figure 5; And

? Figure 7 ? a side view of the control system in figure 5.

DETAILED DESCRIPTION OF THE INVENTION

In the attached figures? schematically represented is an intake valve 1 for a duct of a cylinder system 2, represented merely schematically for exemplary purposes, of an internal combustion engine (not shown), advantageously of the split-cycle type.

The cylinder system 2, as known, defines a seat 3 configured to be selectively blocked by the valve 1, illustrated in a simplified manner in the figures attached for clarity.

The valve 1, for this purpose, includes a stem portion 1b extending along a longitudinal axis A and a shutter portion 1a carried by a lower portion 1? of the rod portion 1b and configured to selectively cooperate with the seat 3 to selectively block it so as to allow, or deny, the passage of high pressure compressed air, i.e. for example greater than 70-80 bar, inside the cylinder 2 system.

Valve 1? controlled via a control system 5 according to the invention configured to impart a force to an upper portion of the rod portion 1b so as to linearly move the rod 1b along the longitudinal axis A passing between a first configuration, in which the mushroom portion 1b does not cooperate in contact with seat 3, allowing the passage of fluid, and a second configuration in which the mushroom portion cooperates in contact with seat 3, blocking it.

In particular, the control system 5 includes a force multiplier device 6, a cam system 7 configured to control the force multiplier device 6 to switch from the second to the first configuration mentioned above and a recall system 8 configured to control the force multiplier device force 6 to go from the first to the second configuration mentioned above.

The force multiplier device 6 ? connected to an upper portion 1?? of the rod 1b of the valve 1 and ? configured to multiply a force imparted by the cam system 7 or by the return system 8 to move the valve 1 along the longitudinal axis A.

In particular, the force multiplier device 6? housed inside a seat 11 defined by a support 12 configured to be connected to the vehicle's engine, for example to the engine head (not shown). In particular, in the illustrated embodiment, the support 12 can be fixed to the engine head via a pair of eyelets 12? fixed to the support 12 and advantageously made integrally with the same.

Headquarters 11? advantageously shaped, so? like the support 12, cup-shaped, therefore laterally delimited by the walls of the support 12, open on a first side along the longitudinal axis A and partially open, through an opening coaxial to the axis A on the opposite side, suitable for housing the part of the force multiplier device 6 and of the valve 1.

Advantageously, the force multiplier device 6 includes a recirculating ball screw 13 operatively interposed between the support 12 and the valve 1 and controlled in rotation by the cam system 7 or by the return system 8 so as to extract or extend the valve 1 compared to seat 3.

In particular, the ball screw 13 includes a nut 14 housed in a rotationally free manner with respect to the support 12 and a screw 15 housed in a free manner for translation along the axis A but blocked for rotation with respect to the support 12.

The nut 14 and the screw 15 cooperate with each other through a plurality? of spheres, as known, circulating inside a thread 16 with pitch P obtained between screw 14 and nut 15.

In more detail, the nut 14 ? housed almost entirely? in space 11 and ? supported freely with respect to the seat 12 by means of rolling means 17. For example, the rolling means 17 can include two rings of rolling balls configured to slide between the nut 14 and the seat 12.

Screw 15? integral with valve 1 and in particular ? fixed integrally to the upper portion 1?? of the valve 1. In the illustrated embodiment the screw 14? quarry and defines a seat 18 within which ? housed the upper portion 1?? of valve 1.

This last one? advantageously connected to one end? of the upper portion 1?? protruding from the seat 18 to the screw 15 via a threaded connection 19, such as a tightening nut.

Returning to the nut 14, it is integral with an actuation portion 21 extending above the support 12, along the axis A. The actuation portion 21 essentially includes an annular disk 22 configured to be fixed to the nut 14 via, for example, threaded elements 23 and more ? preferably concentric to the longitudinal axis A.

The actuation portion 21 further includes an actuator pin 24 extending axially from the annular disk 22 parallel to the longitudinal axis A but radially spaced from it. Advantageously, the actuator pin 24? shaped like a cylindrical pin.

Preferably the actuator pin 24 can include an internal portion 24? integral with the annular disk 22 and preferably made integral with it and an external portion 24?? housed around the internal portion 24? and configured to cooperate in contact with the cam system 7 and the recall system 8.

The cam system 7 and the return system 8 act on the force multiplier device 6, therefore on the external portion 24?? of the actuator pin 24, in a collinear manner along a common axis B perpendicular to the longitudinal axis A and radially spaced from it, providing respective forces in the opposite direction to each other along the axis B.

In particular, the cam system 7 and the return system 8 act in such a way as to allow rotation of the force multiplier device 6 along the axis A in rotation directions opposite to each other. Therefore, they act as opposite sides of the external portion 24?? of the actuator pin 24.

How in itself? known, the rotation along the axis A allows a movement of the screw along the axis A itself as a function of the pitch length P. According to the invention, it is it is sufficient to provide one or a few millimeters of travel of valve 1, therefore, with a pitch of one or a few tens of millimetres, it is possible with a small angular stroke around axis A to precisely control this movement of valve 1.

In order to provide greater coupling between screw 14 and support 12 so as to allow only translation along the A axis, the force multiplier device 6 also includes? locking means 25 configured to couple the screw 14 and the support 12 to rotation.

In greater detail, as visible in figure 3, the locking means 25 include a pin 26 configured to fit into a seat 27 obtained between the screw 14 and the support 12 so as to extend along an axis perpendicular to the axis A from side to part of the support 12 in contact with the screw 14.

The locking means 25 are also configured to limit the maximum permissible stroke, in both directions, along the A axis of screw 14.

To this end, advantageously, the seat 27 has an extension, along the screw 14 in the direction of the longitudinal axis A greater than the diameter of the pin 26 and equal to the maximum allowable stroke of the screw 14 itself, which can be varied according to pre-established limits and project needs.

The cam system 7 is, as mentioned, configured to bring the force multiplier device 6 into the first operating configuration from the second operating condition.

The cam system 7 essentially includes a rotating shaft 31 around an axis C perpendicular to the above-mentioned axes A and B and a cam 32 integral with the rotating shaft 31 defining an actuator portion 32? configured to actuate the force multiplier device 6 along the B axis as described above.

Advantageously, the cam system 7 also includes a tappet 33 operationally interposed between the cam 32 and the force multiplier device 6 advantageously realized as a hydraulic tappet suitable for recovering the play. The tappet 33? advantageously carried by the engine head, even if not illustrated for greater clarity.

The recall system 8 essentially comprises an elastic device 35 configured to maintain the force multiplier device 6 in the second operating configuration.

In particular, the elastic device 35 includes a spring 36, advantageously a helical type spring coaxial to the B axis placed between the motor head (not shown) and a return pin 37 configured to cooperate in contact with the actuator pin 24.

The return pin 37 ? housed in a seat integral with the engine head and is mobile in it along the B axis under the action of the spring 36 and the actuator pin 24.

The control system 5 can? further comprise a return system 41 configured to provide a force to the valve 1 capable of maintaining it in the second configuration.

This recall system 41 ? auxiliary, albeit to a lesser extent, to the force multiplier device 6 and ? useful when assembling valve 1 to prevent it from falling into the cylinder 2 system.

In particular, the return system 41 includes a spring 42 advantageously of the helical type and housed around the valve 1, preferably coaxial to the longitudinal axis A, and configured to cooperate, on one side, with a portion of the cylinder system 2 and, on the ?other, with the lower portion of the force multiplier device 6.

In figures 5 to 7? an alternative embodiment is illustrated where more valves 1 are controlled by respective control systems 5 as described above and therefore not repeated for brevity.

As can be seen from figures 6 and 7, in this embodiment, ? a single support 12 is provided defining respective seats 11 to house the relative force multiplier 6 for the two valves 1.

In particular, the cam mechanism 7 includes two cams 32 carried by the common camshaft 31 whose actuator portion 32? ? angularly arranged with respect to the C axis according to the project requirements for timing the opening of valve 1. Consistently, on the other hand, the return mechanism includes two elastic devices 35, one for each cam 32.

Again as visible in figures 6 and 7, the actuator pins 24 of the force multiplying mechanisms 6 are placed on the opposite side to each other with reference to the longitudinal axis A of the respective valve 1. Furthermore, the thread 16 between the screw 15 and the lead screw 14 of each of the force multiplier mechanisms 6? in the opposite direction. Therefore, the rotation to effect the lengthening of the stem 1a of a first valve 1? the opposite of the other.

The operation of the embodiment of the control system according to the invention described above is the following.

In an engine operating cycle, as described here split-cycle, the cam 32 is rotated by the shaft 31 as a function of the angular rotation of the engine going with the actuator portion 32? to urge the tappet 33 which, by recovering the play, in turn urges the pin 24. The force exerted on the pin 24 overcomes the resistance of the force exerted by the elastic device 35 and sets the nut 14 in rotation which in turn, by rotating, would tend to rotate the screw 15. However, due to the blocking means 25, the screw 15 therefore slides along the axis A, opening the seat 3 and allowing the passage of the air towards the cylinder.

When the rotation of the shaft 31 moves the actuator portion 32? from contact with the tappet 33, the elastic device 35 returns, with the force exerted by it, the pin 24 to the initial position, therefore where the valve 1 cooperates with the seat 3 to prevent the passage of air towards the cylinder.

In the two-valve configuration, the operation is ? the same where, in particular, the direction of rotation of the pin 24 is? opposite, going like this? to compensate for any overturning moments.

From the foregoing, the advantages of a control system according to the invention are evident.

Thanks to the proposed control system? It is possible to control the opening and closing of a valve per cylinder of an internal combustion engine very precisely and with springs that provide standard actuation forces.

In particular, thanks to the force multiplication effect of the 6 multiplier device, it is It is possible to control the opening of the valve with standard springs even in the presence of high air pressures entering the cylinder. In fact, the actuation force provided by the cam system and the return system is multiplied by the multiplier device 6 in order to overcome the forces acting on the valve 1.

Thanks to the fact that a recirculating ball system is used, in itself? irreversible if not implemented as illustrated by the nut, opening and closing are stable to pressure fluctuations.

Furthermore, the recirculating ball system is extremely precise, even for the low strokes used in the system described here, of around 1 or 2 mm, as well as? having a long fatigue life.

In particular, the actuation via a hydraulic tappet cam allows for the recovery of any play due to wear, given that these systems must withstand high numbers of cycles.

Furthermore, the use of a screw-nut system makes it possible, by varying the pitch of the screw-nut system, to easily vary the necessary force to be imparted by the recall device, according to the design needs.

Furthermore, the two-valve setup is made in such a way as to allow housing inside the two elastic devices 35 of the injector and not to interfere with the mechanism for controlling the output valves.

Finally, it is clear that modifications and variations can be made to the control system according to the present invention which however do not go outside the scope of protection defined by the claims.

Clearly? It is possible to use different force multiplication devices, such as for example worm screw systems or other gear trains with equivalent function.

Furthermore, the cam system or the recall system shown can be replaced by similar systems.

Clearly the control system can? be modified to control one, two or more? valves as needed? of the engine system.

Again, although particularly suited to a split-cycle engine, this control system could also be used on any internal combustion engine.

Claims (15)

1.- Control system (5) for a valve (1) of an internal combustion engine system, said control system (5) being configured to control said valve (1) to switch between a first configuration in which it does not cooperate to contact in a respective seat (3) of said motor system and a second configuration in which it cooperates in contact with said seat (3), said control system (5) comprising a force multiplier device (6), a cam system (7) and a recall system (8), said cam system (7) being configured to impart a force to said force multiplier device (6) to transition from said second to said first configuration, said recall system (8) being configured to impart a force to said force multiplier device (6) to maintain it in said second configuration, said force multiplier device (6) being configured to multiply the value of the force provided by the cam system (7) or by the return system (8) to drag said valve (1) between said first and second configurations. 2.- System according to claim 1, in which said force multiplier device (6) is configured to drag said valve (1) along its longitudinal axis (A), said forces provided by the cam system (7) or by the return system (8) being applied to said force multiplier device (6) along an axis ( B) perpendicular to said longitudinal axis (A). 3.- System according to claim 1 or 2, wherein said force provided by said recall system (8) is? collinear and opposite to the force provided by said cam system (7). 4.- System according to one of the previous claims, in which said force multiplier device (6) comprises a recirculating ball screw system (13). 5.- System according to claim 4, further comprising a seat (12), carried integral with said motor system, defining a housing (11) for said screw system (13), said screw system (13) being operationally interposed between said seat (12) and said valve (1). 6.- System according to claim 4 or 5, in which said ball screw (13) system comprises a nut screw (14) and a screw (15) cooperating with each other according to a pitch (P), one of said nut (14) and said screw (15) cooperating with said cam system (7) and said return system (8), the other between said nut (14) and said screw (15) being integral with said valve (1 ). 7.- System according to claim 6, in which said nut (14) is housed rotationally free in said support (12) and defining a portion (24) integral therewith configured to cooperate with said cam system (7) and said return system (8), said screw (15) being integral with said valve ( 1), and housed freely for translation along said longitudinal axis (A) but blocked for rotation with respect to said support (12). 8.- System according to one of claims 6 or 7, further comprising locking means (25) interposed between said support (12) and said screw (15) configured to prevent the rotation of said screw (15) with respect to said support (12 ) and limiting the maximum stroke along said longitudinal axis (A) according to pre-established limits. 9.- System according to claim 7 or 8, in which said portion (24) is placed radially spaced from said longitudinal axis. 10.- System according to one of the previous claims, configured to control a pair of valves (1), said system comprising respective control systems (5) according to the previous claims housed in a seat (12) common for said systems (5). 11.- System according to claim 10, in which the portions (24) of the respective systems (5) are placed on opposite sides with respect to the respective longitudinal axis (A). 12.- System according to one of the previous claims, wherein said cam system (7) includes a rotating shaft (31) configured to carry at least one cam (32), said cam (32) being configured to impart said force to said device force multiplier (6). 13.- System according to claim 12, comprising a hydraulic recovery tappet (33) operatively interposed between said cam (32) and said force multiplier device (6). 14.- System according to one of the previous claims, in which said return device (8) comprises an elastic device (35) comprising a spring (36) and a return pin (37), said spring (36) being capable of exerting a force on said return pin (37), said return pin (37) cooperating with said force multiplier device (6). 15. Internal combustion engine system comprising a valve (1), a cylinder system (2) and defining a seat (3) for said valve (1), said valve (1) being adapted to regulate the passage of fluid towards said system cylinder (2) as a function of its cooperation in contact with said seat (3), said engine system comprising a control system for said valve (1) according to any of the previous claims.