GB2593935A - Continuous variable valve duration apparatus - Google Patents

Continuous variable valve duration apparatus Download PDF

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Publication number
GB2593935A
GB2593935A GB2005363.3A GB202005363A GB2593935A GB 2593935 A GB2593935 A GB 2593935A GB 202005363 A GB202005363 A GB 202005363A GB 2593935 A GB2593935 A GB 2593935A
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United Kingdom
Prior art keywords
cam
control pin
rotation axis
cam drive
arm
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Granted
Application number
GB2005363.3A
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GB202005363D0 (en
GB2593935B (en
Inventor
Pattakos Manousos
Pattakos John
Pattakos Emmanouel
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Individual
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Individual
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Publication date
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Publication of GB202005363D0 publication Critical patent/GB202005363D0/en
Publication of GB2593935A publication Critical patent/GB2593935A/en
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Publication of GB2593935B publication Critical patent/GB2593935B/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L1/053—Camshafts overhead type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
    • F01L1/267—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder with means for varying the timing or the lift of the valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/356—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear making the angular relationship oscillate, e.g. non-homokinetic drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • F01L2001/0476—Camshaft bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L2013/10—Auxiliary actuators for variable valve timing
    • F01L2013/103—Electric motors

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

A continuous variable valve duration apparatus for varying an opening duration of a valve comprising: a valve 1, a cam 2 actuating the valve, and a cam drive 3, the cam drive and the cam rotating about the same rotation axis 4. A cam drive arm 5 is secured to the cam drive and a cam arm 6 is secured to the cam. A control pin 7 is displaceable relative to the rotation axis, and a control arm 8 is rotatably mounted on the control pin, with a first connecting rod 9 being pivotally mounted on the cam drive arm and on the control arm or the second connecting rod, and a second connecting rod 10 is pivotally mounted on the cam arm and on the control arm or the first connecting rod. Wherein a displacement of the control pin relative to the rotation axis changes the phase difference angle between the cam drive and the cam enabling a continuous variable valve opening duration of the valve.

Description

CONTINUOUS VARIABLE VALVE DURATION APPARATUS BACKGROUND OF INVENTION
Field of Invention.
The present invention relates to a continuous variable valve duration apparatus. More particularly, the present invention relates to a continuous variable valve duration apparatus which may vary opening duration of a valve according to operation conditions of an engine with a simple construction.
DESCRIPTION OF RELATED ART
Closest prior art is the US5,152,262 patent of Peter H. Parker (assignee: Rover Group limited) and the following set of patents (all with assignee: Hyundai Motor Company): US8,813,704, US9,512,748, US9,822,674, US9,850,789, US9,856,758, US10,174,643 and US10,533,464.
In these patents it is proposed a mechanism that modifies the phase difference between a cam drive and a cam supported on it, they are also proposed several arrangements for the support and the accurate displacement of the mechanism on a cylinder head. SUMMARY OF INVENTION A continuous variable valve duration apparatus according to the present invention may include a cam, a cam arm secured to the cam, a "cam drive" (which may, for instance, be a shaft whereon cam(s) are pivotally mounted, or a gearwheel, or a sprocket pivotally mounted on a camshaft, or a sprocket rotatably mounted on a cylinder head, etc), a "cam drive arm" secured to the cam drive, with a cam rotation center being the same with a cam drive rotation center, with a phase difference angle between the cam and the cam drive variable along a duration of the cam drive, and with a duration control mechanism linked to both, the cam drive and the cam, and varying the phase difference angle between the cam drive and the cam.
The duration control mechanism may include a displaceable control pin, a control arm rotatably mounted on the control pin and two connecting rods, the one pivotally mounted on the cam drive arm and the other pivotally mounted on the cam arm.
In comparison to the closest prior art, the continues variable valve apparatus of the present invention: avoids the sliding keys, the sliding key slots in pins and the sliding friction between cooperating / heavily loaded parts, uses only constant length links pivotally or rotatably mounted, for the support of the mechanism on a cylinder head it does not require bearings other than a set of coaxial bearings as those supporting a conventional camshaft on a cylinder head, it does not require additional structure(s) to bear and displace the control parts, it requires only small modifications in order to fit in existing cylinder heads as add-on, it is more variable providing more than one valve lift profiles per each valve duration.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a preferred embodiment of the present invention. Fig. 2 shows some of the infinite available valve lift profiles of the preferred embodiment.
Fig. 3 shows only two of the variable valve lift profiles of Fig. 2, one with long valve opening duration and another (bold line) having short valve opening duration.
Fig. 4 shows some of the available valve lift profiles in case of linear displacement of the control pin.
Fig. 5 shows what Fig. 4 for another linear displacement of the control pin.
Fig. 6 shows what Fig. 1 after the removal of some parts.
Fig. 7 shows what Fig. 6 partially disassembled.
Fig. 8 shows what Fig. 7 after the removal of some parts and the disassebly of some sets of parts.
Fig. 9 shows what Fig. 8 after the removal of some parts and the disassembly of some sets of parts.
Fig. 10 shows what Fig. 9 after the removal of some parts and the disassembly of some sets of parts.
Fig. 11 shows the control pins of Fig. 1 with their gearwheels.
Fig. 12 shows the parts shown in Fig. 11 from a different viewpoint and disassembled.
Fig. 13 shows the basic parts of the mechanism of the preferred embodiment from another viewpoint.
Fig. 14 shows what Fig. 13 after the rotation of the cam drive for degrees.
Fig. 15 shows valve lift profiles resulting as the control pin rotates about the rotation axis for 60 degrees at 15 degrees steps.
Fig. 16 shows what Fig. 15 for the next 60 degrees of rotation of the control pin about the rotation axis.
Fig. 17 shows what Fig. 16 for the next 60 degrees of rotation of the control pin about the rotation axis.
Fig. 18 shows what Fig. 17 for the next 60 degrees of rotation of the control pin about the rotation axis.
Fig. 19 shows what Fig. 18 for the next 60 degrees of rotation of the control pin about the rotation axis.
Fig. 20 shows what Fig. 19 for the next 60 degrees of rotation of the control pin about the rotation axis.
Fig. 21 shows a part of the mechanism of Fig. 1 with some parts sliced and hatched.
Fig. 22 shows what Fig. 21 from a different viewpoint.
Fig. 23 shows a variation of the interconnection between the cam drive arm, the cam arm and the control arm.
Fig. 23 shows another variation of the interconnection between the cam drive arm, the cam arm and the control arm.
Fig. 25 shows a variation of the control pin design that allows a linear displacement of the control pin.
Fig. 26 shows another preferred embodiment.
Fig. 27 shows exploded the cam mechanism of Fig. 26.
Fig. 28 shows what Fig. 26 from a different viewpoint.
DETAILED DESCRIPTION
In Fig. 1 it is shown a preferred embodiment wherein a valve 1 is actuated by a cam 2.
The cam 2 rotates about a rotation axis 4.
The cam drive 3 rotates about the same rotation axis 4.
A cam drive arm 5 is secured to the cam drive 3.
A cam arm 6 is secured to the cam 2.
On a displaceable control pin 7 it is rotatably mounted a control arm 8.
With a pair of connecting rods 9 and 10 they are linked the cam drive arm 5, the cam arm 6 and the control arm 8.
The various parts of the mechanism and their interconnection is also shown in the Figs. 6 to 14 and 21, 22.
The rotation of the cam drive 3 for an angle forces the cam (through the linkage between the cam drive and the cam) to rotate for another angle. The difference between the two angles varies during a complete rotation of the cam drive: at some angular region of a complete rotation of the cam drive the cam rotates faster than the cam drive, while at some other angular region of a complete rotation of the cam drive the cam rotates slower than the cam drive.
As illustrated in Figs. 13 and 14, wherein the cross is on the cam drive arm, and supposing a counter-clockwise rotation of the cam drive, the initial rotation of the cam drive by a+(pi-a)=pi radians (i.e. 180 degrees) causes the rotation of the cam by pi-f radians, while the rotation of the cam drive for another pi radians (another 180 degrees) causes the rotation of the cam by pi+f degrees. This gives a ratio of (pi+f)/(pi-f) for the mean angular speed of the cam at the two halves of a rotation of the cam drive. For instance, with f=pi/8 (22.5 degrees) the above ratio becomes 1.3.
Depending on the angular displacement of the control pin 7 about the rotation axis 4, the region wherein the cam rotates faster than the cam drive (fast region), and the region wherein the cam rotates slower than the cam drive (slow region), shift angularly.
The cam actuates the valve for only a part of a complete cam rotation (for the rest rotation of the cam, the valve remains closed). Displacing properly the control pin, the fast region shifts wherein the valve is actuated by the cam, which decreases the valve opening duration.
Displacing properly the control pin, the slow region shifts wherein the valve is actuated by the cam, which increases the valve opening duration.
In this preferred embodiment the control pin remains at constant eccentricity from the rotation axis 4 of the cam and is displaced angularly (and not linearly) about the rotation axis 4.
Such an arrangement improves the compactness, the stiffness, the simplicity, the accuracy and the low cost of the mechanism: the bearings required to support / keep the mechanism are a series of coaxial bearings like those used for the mounting / support of a conventional camshaft; the holes in the cam and in the control pin are the bearings wherein the cam drive is supported, while the cam and the control pin are supported on the cylinder head by a series of coaxial bearings, like 11.
As shown in Figs. 15 to 20 (same cam in all cases, same scale for the horizontal axis (valve lift) and for the vertical axis (cam drive rotation angle) in all cases), a small rotation of the control pin can cause a significant change of the valve lift profile and of the valve opening duration. For instance, the valve duration can vary from too short, say 170 crankshaft degrees (Fig. 15) to extra wide, say 300 crankshaft degrees (Fig. 18), while for the same duration they are available more than one valve lift profiles as shown, for instance, in Fig. 18 wherein for a similar valve opening duration, the valve can open faster than it closes (case of the left curve), or the valve can open slower than it closes (case of the right curve), or the valve can open as fast as it closes (middle curve). According the previous, the control system of the engine has more options; it can optimise the operation of the engine by selecting (among the available valve lift profiles that provide the desirable valve opening duration) the valve lift profile that fits better to the instant operational conditions.
Figs. 15 to 20 show also that the proper selection of the region of the rotation angles of the control pin around the rotation axis can eliminate the need for a VVT (Variable Valve Timing) system, which is important for simple / low cost applications (for instance, for motorcycle engines, for small generator sets etc). According Fig. 20, with 60 degrees of rotation of the control pin about the rotation axis, the large variation of the valve opening duration comes with a relatively small variation of the valve opening (which protects an intake valve from collision with a piston head). That is, the offset of the "peak valve lift" as the valve opening duration changes, can be beneficial.
The mechanism shown in Figs. 1 can be regarded as controlling the intake (or the exhaust) valves of a conventional 16-valve in-line 4-cylinder 4-stroke engine; the valves of each pair of cylinders are controlled by a mechanism as that shown in Figs. 21 and 22. For the intake valves of a six in-line 24-valve 4-stroke engine they would be required three mechanisms like that shown in Figs. 21 and 22.
In Fig. 1 the right pair of control pins is secured on a gearwheel 12 which is intermeshed with a worm gear 13, which is driven by a motor 14. The left pair of control pins are secured to another gearwheel (like 12) which can be driven by another worm gear (like 13), with the worm gear driven either by another motor (like 14) or by the same motor 14 through a pair of sprockets (one per worm gear) and a toothed belt engaging the sprockets.
Fig. 23 shows a variation wherein the two connecting rods are pivotally mounted on different pivots of the control arm.
Fig. 24 shows another variation wherein the one connecting rod (the left one) is pivotally mounted on the other connecting rod, but not directly on the control arm.
Fig. 25 shows one more variation wherein the control pin at middle (which is also shown at left, with the gearwheel secured on it) is modified as shown at top-right or at bottom-right. The slot in the control pin allows its linear displacement relative to the rotation axis, and requires support on respective linear bearings formed in the cylinder head. The control pin can be displaced as described analytically in the patents of the closest prior art.
Fig. 4 shows a set of available valve lift profiles of variable duration in case it is used a control pin like the one at top-right of Fig. 25. Fig. 5 shows a set of available valve lift profiles of variable duration in case it is used a control pin like the one at bottom-right of Fig. 25.
In another preferred embodiment, Figs. 26 to 28, the cam drive 3 is the center of a sprocket (which is engaged, through a chain, with another sprocket on a crankshaft and rotates at half crankshaft speed in case of a 4-stroke engine, or at crankshaft speed in case of a 2-stroke engine), the cam drive arm 5 is the sprocket with the eccentric pin secured on it; the cam 2 is a conventional camshaft with rotation axis the same as the rotation axis of the cam drive 3: the cam drive 3 is pivotally mounted on the cam 2; the cam 2 has a cam arm 6 secured on it; the cam arm 6 passes through an opening of the sprocket and through a connecting rod 10 is linked to the control arm 8, which is rotatably mounted on the control pin 7, with the control pin 7 rotatably mounted on the cam 2. The control arm 8 is linked to the cam drive arm 5 by a connecting rod 9. A lever extends from the control pin 7 (the lever is shown having a ball at its top end); the displacement of the lever (either manually, or by a motor) rotates the control pin 7 about the rotation axis for an angle, the control arm changes position and a valve opening duration varies continuously. This embodiment fits better with cylinder heads controlling one cylinder (single cylinder engines, Vee-twin engines, two-cylinder boxer engines etc) and requires only few minor modifications in order to be installed in existing cylinder heads as add-on: instead of securing the sprocket to the camshaft, the sprocket is pivotally mounted on the camshaft, with the control pin being rotatably mounted on the camshaft, too. For instance, applying the above mechanism on the intake (and/or exhaust) camshafts of a 2-cylinder in Vee Ducati Panigale Desmodromic motorcycle (desmoromic: the valve not only opens positively, but it also closes positively by means of an additional cam lobe and rocker-arm), the engine remains as desmodromic as before, but the originally constant valve opening duration can vary continuously (or in steps) in a wide range: it is like replacing the opening and closing camlobes by infinite narrower and wider ones. For instance: after the modification, the driver of the abovementioned motorcycle can select manually the position of the lever (i.e. the valve opening duration), and the control unit of the engine, based on the rotation angle of the lever, can choose a different set of ignition and injection maps.
For instance, after the modification, the ECU (Electronic Control Unit) of the Ducati Panigale engine, based on the existing operational conditions, can command a motor to displace angularly the lever in order to change the valve opening duration, aligning properly the injection and the ignition.
The continuous variable valve duration apparatus of the present invention is applicable in 4-stroke engines, in 2-stroke engines, in pumps etc. Although the invention has been described and illustrated in detail, the spirit and scope of the present invention are to be limited only by the terms of the appended claims.

Claims (12)

  1. CLAIMSWhat is claimed is: 1. A continuous variable valve duration apparatus comprising: a valve (1); a cam (2) actuating the valve (1); a cam drive (3), the cam drive (3) and the cam (2) rotating about the same rotation axis (4); a cam drive arm (5) secured to the cam drive (3); a cam arm (6) secured to the cam (2); a control pin (7), the control pin (7) being displaceable relative to the rotation axis (4); a control arm (8) rotatably mounted on the control pin (7); a first connecting rod (9); a second connecting rod (10), the first connecting rod (9) being pivotally mounted on the cam drive arm (5) and on at least one of the control arm (8) and of the second connecting rod (10), the second connecting rod (10) being pivotally mounted on the cam arm (6) and on at least one of the control arm (8) and of the first connecting rod (9); wherein a rotation of the cam drive (3) about the rotation axis (4) by an angle forces the cam (2) to rotate about the rotation axis (4) by another angle, with a phase difference angle between the cam drive (3) and the cam (2) being waving / undulated along a complete rotation of the cam drive (3) about the rotation axis (4); wherein a displacement of the control pin (7) relative to the rotation axis (4) changes the phase difference angle between the cam drive (3) and the cam (2) enabling a continuous variable valve opening duration of the valve (1).
  2. 2. The continuous variable valve duration apparatus of claim 1, wherein the first connecting rod (9) is pivotally mounted on the second connecting rod (10).
  3. 3. The continuous variable valve duration apparatus of claim 1, wherein the cam drive (3) is rotatably mounted on the control pin (7).
  4. 4. The continuous variable valve duration apparatus of claim 1, wherein the control pin (7) is angularly displaceable around the rotation axis (4).
  5. 5. The continuous variable valve duration apparatus of claim 1, wherein an angular displacement of the control pin (7) about the rotation axis (4) varies a phase difference angle between the cam drive (3) and the cam (2).
  6. 6. The continuous variable valve duration apparatus of claim 1, wherein a motor (14) being used to rotate at a desirable angle the control pin (7) about the rotation axis (4) to change a valve opening duration of the valve (1).
  7. 7. The continuous variable valve duration apparatus of claim 1, wherein the cam (2) and the control pin (7) are rotatably supported on a cylinder head by bearings (11) centered to the rotation axis (4).
  8. 8. The continuous variable valve duration apparatus of claim 1, wherein a center of the control pin (7) being eccentric relative to the rotation axis (4); wherein a gearwheel (12) is secured on the control pin (7), the rotation for an angle of the gearwheel (12) causes the angular displacement of the control pin (7) about the rotation axis (4), which in turn causes the displacement of the control arm (8), which in turn varies a valve duration of the valve (1).
  9. 9. The continuous variable valve duration apparatus of claim 1, wherein the control pin (7) comprises a slot or hole allowing a variable eccentricity of the control pin (7) relative to the rotation axis (4).
  10. 10. The continuous variable valve duration apparatus of claim 1, wherein two control pins secured to each other control the valve opening duration of at least two valves belonging to neighbouring cylinders.
  11. 11. The continuous variable valve duration apparatus of claim 1, wherein the cam drive arm (5) is a sprocket or gearwheel used for the synchronization of the cam drive with a crankshaft of an engine.
  12. 12. The continuous variable valve duration apparatus of claim 1, wherein: the cam (2) is a camshaft, the cam drive arm (5) is a sprocket, or gearwheel, having an eccentric pin secured on it, the cam drive (3) is the center of the sprocket, the control pin (7) is an eccentric pin rotatably mounted on the cam (2).
GB2005363.3A 2020-04-06 2020-04-14 Continuous variable valve duration apparatus Active GB2593935B (en)

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GB2593935A true GB2593935A (en) 2021-10-13
GB2593935B GB2593935B (en) 2022-11-30

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2365508A (en) * 2000-08-08 2002-02-20 Mechadyne Internat Plc Variable valve timing mechanism

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2365508A (en) * 2000-08-08 2002-02-20 Mechadyne Internat Plc Variable valve timing mechanism

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GB202005363D0 (en) 2020-05-27
GB2593935B (en) 2022-11-30
GB202005068D0 (en) 2020-05-20

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