INTERNAL COMBUSTION ENGINE WITH CAMSHAFT VALVE PHASE VARIATION DEVICE

Abstract

A combustion engine for a vehicle includes a first centrifugal device for varying timing of a first plurality of suction or relief valves with respect to the drive shaft. A driving disc is mounted idle on a first camshaft which controls the valves, and at least one driven disc is integral with the camshaft. Drive elements for transmitting motion from the driving disc to the driven disc are interposed between the two discs causing a relative rotation of the driven disc with respect to the driving disc when the rotation speed of the discs exceeds a predetermined threshold. A distribution system connects the drive shaft with the driving disc so as to cause the rotation thereof. A second gear meshes with a first gear so that rotation of the driving disc mounted on the first camshaft causes the rotation of the second camshaft to control other valves of the engine.

Claims

1. An internal combustion engine for a motor vehicle having a ridable seat, wherein said engine comprises a drive shaft, a first camshaft which controls a plurality of suction valves and a second camshaft which controls a plurality of relief valves, wherein said engine comprises at least a first centrifugal device for varying the timing of the valves, of one of said plurality of valves, with respect to said drive shaft, wherein said first device comprises: a driving disc mounted idle on one of said camshafts which controls said one of said plurality of valves, said drive disc rotating about the rotation axis of said one of said camshafts; at least one driven disc which is integral with said one of said camshafts; drive elements for transmitting the motion between said driving disc and said driven disc, wherein said discs and said drive elements are configured so as to cause a relative rotation of said driven disc with respect to said driving disc when the rotation speed of said discs exceeds a predetermined threshold, a distribution system which mechanically connects said drive shaft with said driving disc so as to cause the rotation thereof; characterized in that said engine comprises a first gear which is integral with said driving disc and a second gear mounted on the other of said camshafts so that the rotation of said second gear directly or indirectly causes the rotation of said other of said camshafts, wherein said second gear directly meshes with said first gear so that the rotation of said driving disc causes the rotation of said other of said camshafts which controls the other of said plurality of valves.

2. The engine according to claim 1, wherein said distribution system comprises a first distribution wheel keyed onto said drive shaft, a second distribution wheel which is integral with said first disc, and a flexible drive element which connects said distribution wheels so that the rotation of said drive shaft is transferred to said driving disc.

3. The engine according to claim 2, wherein said engine comprises a sleeve body which is integral in rotation with said driving disc, wherein said driving disc is placed at a first end of said sleeve body, which comprises a flange portion defined at a second end, opposite to said first end, said second distribution wheel being connected to said flange portion of said sleeve body.

4. The engine according to claim 3, wherein said engine comprises axial preloading means which act on said driving disc by opposing the axial translation with respect to said driven disc along a direction parallel to the rotation axis of said one of said camshafts.

5. The engine according to claim 1, wherein said first gear is made in one piece with said driving disc, which takes on the configuration of a gear wheel.

6. The engine according to claim 1, wherein said second gear is made in one piece with said other of said camshafts.

7. The engine according to claim 1, wherein said first gear is mounted idle on said first camshaft and said second gear is mounted on said second camshaft.

8. The engine according to claim 1, wherein said driving disc is mounted idle on said second camshaft and said second gear is mounted on said first camshaft.

9. The engine according to claim 1, wherein said engine comprises a further centrifugal device for varying the timing of said valves which are controlled by said other of said camshafts, wherein said further device comprises: a further driving disc mounted idle on said other of said camshafts, said further driving disc rotating about the rotation axis of said other of said camshafts; a further driven disc which is integral with said other of said camshafts; further drive elements for transmitting the motion between said further driving disc and said further driven disc, wherein said further discs and said further drive elements are configured so as to cause a relative rotation of said further second disc with respect to said further first disc when the rotation speed of said further discs exceeds a predetermined threshold, wherein said second gear is integral with said further driving disc so that the rotation of said driving disc mounted on said one of said camshafts is transferred to said further driving disc mounted on said other of said camshafts.

Description

LIST OF FIGURES

[0035] Further features and advantages of the invention shall be more apparent from an examination of the following detailed description of some preferred, but not exclusive, embodiments of the engine according to the present invention, shown by way of non-limiting example, with the support of the accompanying drawings, in which:

[0036] FIGS. 1 to 3 are diagrammatic views of an engine known from the prior art;

[0037] FIG. 4 is a diagrammatic view related to a possible embodiment of an engine according to the present invention;

[0038] FIG. 5 is a further view of the engine in FIG. 4;

[0039] FIGS. 6 and 7 are two sectional views according to the sectional line VI-VI and the sectional line VII-VII, respectively;

[0040] FIG. 8 is a further view of the engine in FIG. 4;

[0041] FIG. 9 is an enlargement of the detail IX-IX indicated in FIG. 7;

[0042] FIGS. 10 and 13 are diagrammatic views related to possible embodiments of an engine according to the present invention.

[0043] The same numerals and reference letters in the Figures identify the same elements or components.

DETAILED DESCRIPTION

[0044] The present invention relates to a combustion engine for a motor vehicle having a ridable seat, this term in general meaning a motorcycle or motor vehicle having two, three or four wheels, mainly intended to transport people.

[0045] Engine 1 according to the invention comprises a first camshaft 10, rotating about a first rotation axis 101, and a second camshaft 20, rotating about a second rotation axis 102, for controlling a plurality of suction valves 110 and a plurality of suction valves 210, respectively. Engine 1 likewise comprises at least a first device 2 for varying the timing of the valves 110, 210 of one of the two camshafts 10, 20 with respect to the drive shaft.

[0046] In the embodiment shown in FIGS. 9 to 13, device 2 is applied to the first camshaft 10 to vary the phase of the suction valves 110 with respect to the drive shaft 300. However, as shown in the schematization in FIG. 11, device 2 could be operatively associated with the second camshaft 20 to vary the phase of the relief valves 220. Therefore, while mainly describing the invention with reference to an engine with phase variation provided at the suction (i.e. for the suction valves), the technical solutions may be applied, mutatis mutandi, also to an engine in which the phase variation is provided at the discharge (i.e. for the relief valves). In essence, what is indicated below for the first camshaft and for the second camshaft for a configuration of the engine in which the phase variation is provided at the suction is to be considered valid for the second camshaft and for the first camshaft, respectively, in the event of a configuration of the engine in which the phase variation is provided at the discharge.

[0047] Some of the accompanying Figures (FIGS. 4 to 9) show only certain parts of an internal combustion engine 1 according to the invention, while the other parts, which are not essential to understand the present invention, are not shown for reasons of increased illustrative clarity. Other accompanying Figures, which in any case are comprehensible to those skilled in the art, are only schematizations of possible embodiments of an engine according to the present invention.

[0048] The drive shaft is not shown in the accompanying Figures, rather is diagrammatically indicated with an axis having reference numeral 300. Device 2 is indicated also with the term “phase changer 2” or “phase changer device 2” in the continuation of the description. With reference to the components of the phase changer 2, the terms “axial” and “axially” refer to distances, thicknesses and/or positions assessed along the rotation axis 101, 102 of the first camshaft 10 with which the phase changer is operatively associated.

[0049] According to the invention, the phase changer device 2 employed is of the centrifugal type and therefore operates according to a principle which in itself is known. Device 2 comprises a driving disc 11 (or first disc 11), a driven disc 12 (or second disc 12) and plurality of drive elements 40, each of which being interposed between the two discs 11, 12 indicated above. The drive elements 40 and discs 11, 12 are configured so as to cause a rotation of the second disc 12 with respect to the first disc 11 when the rotation speed exceeds a predetermined threshold.

[0050] For this purpose, according to a principle which in itself is known, the driving disc 11 is mounted idle on the first camshaft 10 so that the two components (the first camshaft 10 and the first disc 11) rotate about the same rotation axis 101. The first disc 11 is “idle”, in the sense that it keeps a degree of freedom of rotation with respect to the first camshaft 10 on which it is mounted, and vice versa.

[0051] The driven disc 12 is connected to the same first camshaft 10 but in an integral manner, i.e. so as to rotate integrally with the same rotation axis 101, 102. Therefore, the two discs 11, 12 rotate about the first rotation axis 101. In this regard, the driven disc 12 may be made in one piece with the first camshaft 10 (as in the Figures) or alternatively made separately, and then rigidly keyed thereto (for example, through a key connection or a connection with grooved profiles).

[0052] According to what is conventionally provided in a centrifugal phase changer, first grooves 31 partially facing second grooves 32 defined on a side 122 of the driven disc 12 are defined on a side 111 of the driving disc 11. Each of the drive elements 40 is partially accommodated in one of said first grooves 31 and partially in one of said second grooves 32. As the centrifugal force increases, caused by the increase of the rotation speed, each of the drive elements 40 moves along the two grooves 31, 32 between a first position, closest to the rotation axis 101 of the two discs 11, 12, to a second position, furthest from the same rotation axis. According to the cases, the first grooves 31 are configured in direction and/or shape in a different manner from the second grooves 32 so that reaching said second position is accompanied by a relative rotation of the second disc 12 with respect to the first disc 11. Such a translation results in the variation of the phase of the valves with respect to the drive shaft 300.

[0053] The detail in FIG. 9 allows a possible, and therefore non-exclusive, embodiment of the phase changer device 2 according to the invention, to be noted. In the embodiment shown in particular, the phase changer 2 comprises preloading means 70 configured so as to oppose the axial movement of the first disc 11 with respect to the second disc 12, and therefore so as to keep the drive elements 40 between the two discs 11, 12, each in the two grooves (first groove 31 and corresponding groove 32) in which it is accommodated.

[0054] In the possible and non-exclusive embodiment shown in FIG. 9, the preloading means 70 comprise a Belleville spring 71 which acts on the flange portion 61 of the sleeve body 62 so as to push the latter towards the second disc 12. The Belleville spring 71 is interposed between the flange portion 61 and an adjusting screw 72 which coaxially screws to the end of camshaft 10, about which the flange portion 61 is arranged. The closing of screw 72 results in the compression of the Belleville spring 71, and therefore in an axial force which opposes the first disc 11 moving away from the second disc 12.

[0055] The axial preloading means 70 could therefore be configured to prevent the relative movement of the first disc 11 with respect to the second disc 12, or only to counter such a movement, as occurs in the device described in U.S. Pat. No. 9,719,381 indicated above.

[0056] The phase changer 2 shown in FIG. 9 further comprises means 6 for retaining the drive elements 40 interposed between the first disc 11 and the second disc 12. Such retaining means 6 act on the drive elements 40, applying on each of them a force which tends to push the drive element 40 towards the first position indicated above (i.e. towards the rotation axis 101). The employment of retaining means 6 allows the clearances to be recovered between the drive elements 40 and the grooves 31, 32, thus making the transmission more efficient and at the same time allowing the shape of the components of the device itself to be simplified.

[0057] It is worth noting again that the shape of device 2, shown in detail in FIG. 9, is not essential for the invention, whose new and inventive features are described below. In this regard, device 2 could take on the configuration described in U.S. Pat. No. 9,719,381 indicated above.

[0058] In any event, according to the present invention, engine 1 comprises a distribution system 5 which mechanically connects the drive shaft 300 to the driving disc 11 so as to cause the rotation thereof about the rotation axis 101 thereof.

[0059] Again, according the invention, the driving disc 11 is integral with a first gear 15. Such a first gear 15 preferably is made in one piece with the driving disc 11 so that the driving disc 11 takes on the configuration of a wheel. In essence, in this shape, the driving disc 11 comprises an external ring gear defining the first gear 15. Engine 1 according to the invention comprises a second gear 16 mounted on the second camshaft 20 so that the rotation of the second gear 16 directly or indirectly causes the rotation of the second camshaft 20. According to the invention, the second gear 16 meshes with the first gear 15 so that the rotation of the first disc 11, mounted on the first shaft 10, is transferred, through the second gear 16, to the second camshaft 20. Advantageously, the rotation of the second camshaft 20 is therefore caused by the driving disc 11 of the phase changer device 2 provided for varying the timing of the valves controlled by the first camshaft 10.

[0060] As better described below, the term “directly” refers to a possible embodiment in which the second gear 16 is keyed onto the second camshaft 20 so as to rotate integrally therewith. The term “indirectly” instead refers to a possible embodiment in which the phase variation is provided both at the suction and at the discharge. In this hypothesis, the second gear 16 is integral with the driving disc 11B of a further phase changer device 2B operatively associated with the second camshaft 20 to vary the timing of the relief valves (see FIGS. 12 and 13).

[0061] According to a possible embodiment shown in FIGS. 5 to 9, the distribution system 5 comprises a first distribution wheel 51, keyed onto the drive shaft 300 (indicated with a dashed line in FIG. 2), a second distribution wheel 52 which is integral with the first disc 11, and a flexible drive element 53 (in the form of chain or belt) which connects the two distribution wheels 51, 52 so that the rotation of the drive shaft 300 is transferred to the first disc 11 of the phase changer 2.

[0062] According to the embodiment (it also shown in FIGS. 4 to 9), the second distribution wheel 52 is connected to a flange portion 61 of a sleeve body 62 made in one piece with the driving disc 11. The driving disc 11 in particular is defined at a first end of the sleeve body 62, opposite to a second end defining the flange portion 61. The second distribution wheel 52 preferably is connected to the flange portion 61 through screw connection means 66 (see FIGS. 4 and 6). With reference to FIGS. 6 to 9, the sleeve body 62 preferably is mounted to an end part 10A of camshaft 10 so that the first disc 11 faces the second disc 12 for the objects already indicated above.

[0063] FIGS. 10 to 13 are schematizations of four possible embodiments (indicated by reference numeral 1, 1B, 1C, 1D) of the engine according to the present invention. The embodiment schematized in FIG. 10 substantially corresponds to the one shown in FIGS. 4 to 9.

[0064] The embodiment shown in FIG. 11 refers to an engine 1B according to the invention, in which there is provided a phase variation at the discharge and therefore in which the phase changer device (indicated by reference numeral 2B) is operatively associated with the second shaft 20. As a result, the driving disc (indicated by 11B) is mounted idle on the second camshaft 20, while the driven disc (indicated by 12B) is integral with the same second camshaft 20. The second gear 16 which meshes with the first gear 15 which is integral with the driving disc 11B instead is keyed onto the first camshaft 10. According to the principles of the invention, the distribution system 5 is in any event configured to cause the rotation of the driving disc 11B. Therefore, sleeve 62, with which the second distribution wheel 52 and the same driving disc 11B are integral, is mounted at the end of the second camshaft 20.

[0065] It is worth noting in the embodiment shown in FIG. 11 that the suction valves 110 always keep the same timing with respect to the drive shaft 300. Indeed, the rotation of the first camshaft 10, caused by the distribution system, is transferred through the transmission defined by the first gear 15 (integral with the driving disc 11B) and by the second gear 16. The second camshaft 20 is therefore excluded from such a transmission, which second camshaft remains free to vary the angular position thereof with respect to the driving disc 11B to cause the phase variation of the relief valves 220.

[0066] FIG. 12 relates to a possible embodiment (already mentioned above), in which the engine comprises a first device 2 operatively associated with the first camshaft 10 to vary the timing of the suction valves 110 and a second device (indicated by 2B) associated with the second camshaft 20 to vary the phase of the relief valves 220. In other words, in the configuration in FIG. 12, the phase variation is provided both for the suction and for the discharge.

[0067] The driving disc 11 of the first device 2A is therefore mounted idle on the first camshaft 10, while the related driven disc 12 is integral in rotation with the same first camshaft 10. In an entirely similar manner, the driving disc (indicated by 11B) of the second device 2B is mounted idle on the second camshaft 20, while the related driven disc (indicated by 12B) is integral in rotation with the second camshaft 20. The distribution system is configured to cause the rotation of the driving disc 11 of the first device 2. Therefore, sleeve 62, which is connected to the second distribution wheel 52, is keyed idle to the end of the first camshaft 10.

[0068] In the embodiment in FIG. 12, the second gear 16 is integral with the first disc 11B of the second device 2B provided to vary the timing of the relief valves 220. In this embodiment, the second gear 16 is mounted idle on the second camshaft 20 and indirectly transfers the motion to the second camshaft 20 through the second device 2B.

[0069] Again with reference to the embodiment in FIG. 12, overall the assembly of components formed by sleeve 62, the driving disc 11 of the first device 2, the first gear 15, the second gear 16 and the driving disc 11B of the second device 2B, always rotate in phase with the drive shaft 300. The two camshafts 10, 20, and therefore the related valves 110, 220, may instead vary the timing angle thereof with respect to the drive shaft 300.

[0070] The embodiment shown in FIG. 13 differs from the one in FIG. 12 exclusively in that the distribution system is configured to cause the rotation of the driving disc 11B of the second device 2B. Here, sleeve 62, which is connected to the second distribution wheel 52, therefore is keyed idle to the end of the second camshaft 20. Accordingly, the first gear 15 is integral with the driving disc 11B of the second device 2B, while the second gear 16 is integral with the driving disc 11 of the first device 2. Therefore, the operating position of the two gears 15, 16 is inverted with respect to the embodiment shown in FIG. 12. In any event, for both embodiments discussed (FIG. 12 and FIG. 13), the rotation conferred to the driving disc (11 or 11B) connected to the distribution system 5 is exploited not only to rotate the camshaft (10 or 20) on which the same driving disc (11 or 11B) is mounted idle, but also to rotate (through the two gears 15, 16) the other camshaft (20 or 10). This solution in any event allows a simple configuration of the distribution system to be kept because there is provided one distribution wheel alone associated with one of the camshafts. In other words, by using the same distribution system, it may be used both in a configuration in which the phase variation is provided for one type alone of valves (suction or discharge) and in a configuration in which the phase variation is provided for both types of valves (suction and discharge).